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Sample records for peri-operative contamination model

  1. Peri-operative care.

    Science.gov (United States)

    Baston, Helen

    2004-05-01

    This is the third 'midwifery basics' series aimed at student midwives, and focuses on midwifery care during labour. This article provides a summary of peri-operative care for women who experience caesarean birth. Students are encouraged to seek further information through a series of activities, and to link theory with practice by considering the issues relating to the care of the woman described in the short vignette.

  2. Peri-operative cognitive dysfunction and protection

    DEFF Research Database (Denmark)

    Steinmetz, J; Rasmussen, L S

    2016-01-01

    Cognition may decline after surgery. Postoperative delirium, especially when hyperactive, may be easily recognised, whereas cognitive dysfunction is subtle and can only be detected using neuropsychological tests. The causes for these two conditions are largely unknown, although they share risk...... factors, the predominant one being age. Ignorance of the causes for postoperative cognitive dysfunction contributes to the difficulty of conducting interventional studies. Postoperative cognitive disorders are associated with increased mortality and permanent disability. Peri-operative interventions can...... reduce the rate of delirium in the elderly, but in spite of promising findings in animal experiments, no intervention reduces postoperative cognitive dysfunction in humans....

  3. A systematic review of peri-operative melatonin

    DEFF Research Database (Denmark)

    Andersen, L P H; Werner, M U; Rosenberg, J

    2014-01-01

    We systematically reviewed randomised controlled trials of peri-operative melatonin. We included 24 studies of 1794 participants that reported eight peri-operative outcomes: anxiety; analgesia; sleep quality; oxidative stress; emergence behaviour; anaesthetic requirements; steal induction......%, respectively. Qualitative reviews suggested the melatonin improved sleep quality and emergence behaviour, and might be capable of reducing oxidative stress and anaesthetic requirements....

  4. Optimization of peri-operative care in colorectal surgery

    NARCIS (Netherlands)

    Kornmann, V.N.N.

    2016-01-01

    Colorectal cancer is an important health issue, and colorectal surgery is increasingly being performed. During the last years, quality and safety of care, new surgical techniques and attention for peri-operative risks resulted in reduction of postoperative morbidity and mortality. Despite these

  5. The need for peri-operative supplemental oxygen | Chikungwa ...

    African Journals Online (AJOL)

    The need for peri-operative supplemental oxygen. M. T. Chikungwa, K. Jonsson. Abstract. (Central African Journal of Medicine: 2002 48 (5-6): 72-73). AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions of Use ...

  6. Nutrition in peri-operative esophageal cancer management.

    Science.gov (United States)

    Steenhagen, Elles; van Vulpen, Jonna K; van Hillegersberg, Richard; May, Anne M; Siersema, Peter D

    2017-07-01

    Nutritional status and dietary intake are increasingly recognized as essential areas in esophageal cancer management. Nutritional management of esophageal cancer is a continuously evolving field and comprises an interesting area for scientific research. Areas covered: This review encompasses the current literature on nutrition in the pre-operative, peri-operative, and post-operative phases of esophageal cancer. Both established interventions and potential novel targets for nutritional management are discussed. Expert commentary: To ensure an optimal pre-operative status and to reduce peri-operative complications, it is key to assess nutritional status in all pre-operative esophageal cancer patients and to apply nutritional interventions accordingly. Since esophagectomy results in a permanent anatomical change, a special focus on nutritional strategies is needed in the post-operative phase, including early initiation of enteral feeding, nutritional interventions for post-operative complications, and attention to long-term nutritional intake and status. Nutritional aspects of pre-optimization and peri-operative management should be incorporated in novel Enhanced Recovery After Surgery programs for esophageal cancer.

  7. Fast-track surgery: Toward comprehensive peri-operative care.

    Science.gov (United States)

    Nanavati, Aditya J; Prabhakar, S

    2014-01-01

    Fast-track surgery is a multimodal approach to patient care using a combination of several evidence-based peri-operative interventions to expedite recovery after surgery. It is an extension of the critical pathway that integrates modalities in surgery, anesthesia, and nutrition, enforces early mobilization and feeding, and emphasizes reduction of the surgical stress response. It entails a great partnership between a surgeon and an anesthesiologist with several other specialists to form a multi-disciplinary team, which may then engage in patient care. The practice of fast-track surgery has yielded excellent results and there has been a significant reduction in hospital stay without a rise in complications or re-admissions. The effective implementation begins with the formulation of a protocol, carrying out each intervention and gathering outcome data. The care of a patient is divided into three phases: Before, during, and after surgery. Each stage needs active participation of few or all the members of the multi-disciplinary team. Other than surgical technique, anesthetic drugs, and techniques form the cornerstone in the ability of the surgeon to carry out a fast-track surgery safely. It is also the role of this team to keep abreast with the latest development in fast-track methodology and make appropriate changes to policy. In the Indian healthcare system, there is a huge benefit that may be achieved by the successful implementation of a fast-track surgery program at an institutional level. The lack of awareness regarding this concept, fear and apprehension regarding its implementation are the main barriers that need to be overcome.

  8. The peri-operative management of anti-platelet therapy in elective, non-cardiac surgery.

    Science.gov (United States)

    Alcock, Richard F; Naoum, Chris; Aliprandi-Costa, Bernadette; Hillis, Graham S; Brieger, David B

    2013-07-31

    Cardiovascular complications are important causes of morbidity and mortality in patients undergoing elective non-cardiac surgery, with adverse cardiac outcomes estimated to occur in approximately 4% of all patients. Anti-platelet therapy withdrawal may precede up to 10% of acute cardiovascular syndromes, with withdrawal in the peri-operative setting incompletely appraised. The aims of our study were to determine the proportion of patients undergoing elective non-cardiac surgery currently prescribed anti-platelet therapy, and identify current practice in peri-operative management. In addition, the relationship between management of anti-platelet therapy and peri-operative cardiac risk was assessed. We evaluated consecutive patients attending elective non-cardiac surgery at a major tertiary referral centre. Clinical and biochemical data were collected and analysed on patients currently prescribed anti-platelet therapy. Peri-operative management of anti-platelet therapy was compared with estimated peri-operative cardiac risk. Included were 2950 consecutive patients, with 516 (17%) prescribed anti-platelet therapy, primarily for ischaemic heart disease. Two hundred and eighty nine (56%) patients had all anti-platelet therapy ceased in the peri-operative period, including 49% of patients with ischaemic heart disease and 46% of patients with previous coronary stenting. Peri-operative cardiac risk score did not influence anti-platelet therapy management. Approximately 17% of patients undergoing elective non-cardiac surgery are prescribed anti-platelet therapy, the predominant indication being for ischaemic heart disease. Almost half of all patients with previous coronary stenting had no anti-platelet therapy during the peri-operative period. The decision to cease anti-platelet therapy, which occurred commonly, did not appear to be guided by peri-operative cardiac risk stratification. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  9. Peri-operative chemotherapy in the management of resectable colorectal cancer pulmonary metastases

    Directory of Open Access Journals (Sweden)

    Hawkes Eliza A

    2012-08-01

    Full Text Available Abstract Background Surgery is often advocated in patients with resectable pulmonary metastases from colorectal cancer (CRC. Our study aims to evaluate peri-operative chemotherapy in patients with metastastic CRC undergoing pulmonary metastasectomy. Methods Patients treated for CRC who underwent pulmonary metastasectomy by a single surgeon were identified. Outcome measures included survival, peri-operative complications, radiological and histological evidence of chemotherapy-induced lung toxicities. Results Between 1997 and 2009, 51 eligible patients were identified undergoing a total of 72 pulmonary resections. Thirty-eight patients received peri-operative chemotherapy, of whom 9 received an additional biological agent. Five-year overall survival rate was 72% in the whole cohort - 74% and 68% in those who received peri-operative chemotherapy (CS and those who underwent surgery alone (S respectively. Five-year relapse free survival rate was 31% in the whole cohort - 38% and ≤18% in CS and S groups respectively. Only 8% had disease progression during neoadjuvant chemotherapy. There were no post-operative deaths. Surgical complications occurred in only 4% of patients who received pre-operative chemotherapy. There was neither radiological nor histological evidence of lung toxicity in resected surgical specimens. Conclusions Peri-operative chemotherapy can be safely delivered to CRC patients undergoing pulmonary metastasectomy. Survival in this selected group of patients was favourable.

  10. Does training of fellows affect peri-operative outcomes of robot-assisted partial nephrectomy?

    Science.gov (United States)

    Khene, Zine-Eddine; Peyronnet, Benoit; Bosquet, Elise; Pradère, Benjamin; Robert, Corentin; Fardoun, Tarek; Kammerer-Jacquet, Solène-Florence; Verhoest, Grégory; Rioux-Leclercq, Nathalie; Mathieu, Romain; Bensalah, Karim

    2017-10-01

    To evaluate the impact of fellows' involvement on the peri-operative outcomes of robot-assisted partial nephrectomy (RAPN). We analysed 216 patients who underwent RAPN for a small renal tumour. We stratified our cohort into two groups according to the involvement of a fellow surgeon during the procedure: expert surgeon operating alone (expert group) and fellow operating under the supervision of the expert surgeon (fellow group). Peri-operative data were compared between the two groups. Linear and logistic regression analyses were performed to assess the impact of fellows' involvement on peri-operative and postoperative outcomes. Trifecta and margins ischaemia complications (MIC) score achievement rates were used to assess the quality of surgery in both the expert and fellow groups. Trifecta was defined as a combination of warm ischaemia time negative surgical margins and no peri-operative complications. MIC score was defined as negative surgical margins, ischaemia time Training fellows to perform RAPN is associated with longer operating time and WIT but does not appear to compromise other peri-operative outcomes. © 2017 The Authors BJU International © 2017 BJU International Published by John Wiley & Sons Ltd.

  11. International consensus statement on the peri-operative management of anaemia and iron deficiency

    DEFF Research Database (Denmark)

    Muñoz, M.; Acheson, A. G.; Auerbach, M.

    2017-01-01

    Despite current recommendations on the management of pre-operative anaemia, there is no pragmatic guidance for the diagnosis and management of anaemia and iron deficiency in surgical patients. A number of experienced researchers and clinicians took part in an expert workshop and developed...... in the peri-operative period. These statements include: a diagnostic approach for anaemia and iron deficiency in surgical patients; identification of patients appropriate for treatment; and advice on practical management and follow-up. We urge anaesthetists and peri-operative physicians to embrace...

  12. Peri-operative blood transfusion for resected colon cancer: Practice patterns and outcomes in a population-based study.

    Science.gov (United States)

    Patel, Sunil V; Brennan, Kelly E; Nanji, Sulaiman; Karim, Safiya; Merchant, Shaila; Booth, Christopher M

    2017-12-01

    Literature suggests that peri-operative blood transfusion among patients with resected colon cancer may be associated with inferior long-term survival. The study objective was to characterize this association in our population. This is a retrospective cohort study using the population-based Ontario Cancer Registry (2002-2008). Pathology reports were obtained for a 25% random sample of all cases and constituted the study population. Log binomial regression was used to identify factors associated with transfusion. Cox proportional hazards model explored the association between transfusion and cancer specific survival (CSS) and overall survival (OS). The study population included 7198 patients: 18% stage I, 36% stage II, 40% stage III, and 6% stage IV. Twenty-eight percent of patients were transfused. Factors independently associated with transfusion included advanced age (pTransfusion was associated with inferior CSS (HR 1.51, 95% CI 1.38-1.65) and OS (HR 1.52, 95% CI 1.41-1.63), after adjusting for important confounders. Peri-operative transfusion rates among patients with colon cancer have decreased over time. Transfusion is associated with inferior long-term CSS and OS. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. A review of the peri-operative management of paediatric burns ...

    African Journals Online (AJOL)

    Reasons include peri-operative sepsis, bleeding, issues around thermoregulation, the hypermetabolic state, nutritional and electrolyte issues, inhalation injuries and the amount of movement during procedures to wash patients, change drapes and access different anatomical sites. The appropriate execution of surgery is ...

  14. Monitoring of peri-operative fluid administration by individualized goal-directed therapy

    DEFF Research Database (Denmark)

    Bundgaard-Nielsen, M; Holte, Kathrine; Secher, N H

    2007-01-01

    BACKGROUND: In order to avoid peri-operative hypovolaemia or fluid overload, goal-directed therapy with individual maximization of flow-related haemodynamic parameters has been introduced. The objectives of this review are to update research in the area, evaluate the effects on outcome and assess...

  15. Effect of peri-operative chemotherapy on the quality of life of patients with early breast cancer

    NARCIS (Netherlands)

    Kiebert, G. M.; Hanneke, J.; de Haes, J. Hanneke C. J. M.; Kievit, J.; van de Velde, C. J.

    1990-01-01

    Since chemotherapy is assumed to have a negative impact on quality of life, the impact of peri-operative chemotherapy on physical, psychological and social well-being and on the activity level of patients with early stage breast cancer was investigated. 24 women received peri-operative chemotherapy

  16. Modeling for Airborne Contamination

    International Nuclear Information System (INIS)

    F.R. Faillace; Y. Yuan

    2000-01-01

    The objective of Modeling for Airborne Contamination (referred to from now on as ''this report'') is to provide a documented methodology, along with supporting information, for estimating the release, transport, and assessment of dose to workers from airborne radioactive contaminants within the Monitored Geologic Repository (MGR) subsurface during the pre-closure period. Specifically, this report provides engineers and scientists with methodologies for estimating how concentrations of contaminants might be distributed in the air and on the drift surfaces if released from waste packages inside the repository. This report also provides dose conversion factors for inhalation, air submersion, and ground exposure pathways used to derive doses to potentially exposed subsurface workers. The scope of this report is limited to radiological contaminants (particulate, volatile and gaseous) resulting from waste package leaks (if any) and surface contamination and their transport processes. Neutron activation of air, dust in the air and the rock walls of the drift during the preclosure time is not considered within the scope of this report. Any neutrons causing such activation are not themselves considered to be ''contaminants'' released from the waste package. This report: (1) Documents mathematical models and model parameters for evaluating airborne contaminant transport within the MGR subsurface; and (2) Provides tables of dose conversion factors for inhalation, air submersion, and ground exposure pathways for important radionuclides. The dose conversion factors for air submersion and ground exposure pathways are further limited to drift diameters of 7.62 m and 5.5 m, corresponding to the main and emplacement drifts, respectively. If the final repository design significantly deviates from these drift dimensions, the results in this report may require revision. The dose conversion factors are further derived by using concrete of sufficient thickness to simulate the drift

  17. Peri-operative deaths in Singapore: a forensic perspective in a study of 132 cases.

    Science.gov (United States)

    Lau, G

    1994-05-01

    A study of 132, largely non-traumatic, peri-operative deaths out of 6605 Coroner's autopsies, conducted over a three-year period from 1989 to 1991, showed a preponderance of males (M:F ratio = 1.36), with almost half (46.3%) being middle-aged subjects between 40 to 59 years, while infants (negligence was made in any of the Coroner's inquiries into these cases.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Platelet-rich-plasmapheresis for minimising peri-operative allogeneic blood transfusion.

    Science.gov (United States)

    Carless, Paul A; Rubens, Fraser D; Anthony, Danielle M; O'Connell, Dianne; Henry, David A

    2011-03-16

    Concerns regarding the safety of transfused blood have generated considerable enthusiasm for the use of technologies intended to reduce the use of allogeneic blood (blood from an unrelated donor). Platelet-rich plasmapheresis (PRP) offers an alternative approach to blood conservation. To examine the evidence for the efficacy of PRP in reducing peri-operative allogeneic red blood cell (RBC) transfusion, and the evidence for any effect on clinical outcomes such as mortality and re-operation rates. We identified studies by searching MEDLINE (1950 to 2009), EMBASE (1980 to 2009), The Cochrane Library (Issue 1, 2009), the Internet (to March 2009) and the reference lists of published articles, reports, and reviews. Controlled parallel group trials in which adult patients, scheduled for non-urgent surgery, were randomised to PRP, or to a control group which did not receive the intervention. Primary outcomes measured were: the number of patients exposed to allogeneic RBC transfusion, and the amount of RBC transfused. Other outcomes measured were: the number of patients exposed to allogeneic platelet transfusions, fresh frozen plasma, and cryoprecipitate, blood loss, re-operation for bleeding, post-operative complications (thrombosis), mortality, and length of hospital stay. Treatment effects were pooled using a random-effects model. Trial quality was assessed using criteria proposed by Schulz et al (Schulz 1995). Twenty-two trials of PRP were identified that reported data for the number of patients exposed to allogeneic RBC transfusion. These trials evaluated a total of 1589 patients. The relative risk (RR) of exposure to allogeneic blood transfusion in those patients randomised to PRP was 0.73 (95%CI 0.59 to 0.90), equating to a relative risk reduction (RRR) of 27% and a risk difference (RD) of 19% (95%CI 10% to 29%). However, significant heterogeneity of treatment effect was observed (p transfused (weighted mean difference [WMD] -0.69, 95%CI -1.93 to 0.56 units). Trials

  19. Selective use of peri-operative steroids in pituitary tumor surgery: escape from dogma

    Directory of Open Access Journals (Sweden)

    Jacqueline Marie Regan

    2013-03-01

    Full Text Available Objective: Traditional neurosurgical practice calls for administration of peri-operative stress-dose steroids for sellar-suprasellar masses undergoing operative treatment. This practice is considered critical to prevent peri-operative complications associated with hypoadrenalism, such as hypotension and circulatory collapse. However, stress-dose steroids complicate the management of these patients. It has been our routine practice to use stress steroids during surgery only if the patient has clinical or biochemical evidence of hypocortisolism pre-operatively. We wanted to be certain that this practice was safe.Methods: We present our retrospective analysis from a consecutive series of 114 operations in 109 patients with sellar and/or suprasellar tumors, the majority of whom were managed without empirical stress-dose steroid coverage. Only patients who were hypoadrenal pre-operatively or who had suffered apoplexy were given stress dose coverage during surgery. We screened for biochemical evidence of hypoadrenalism as a result of surgery by measuring immediate post-operative AM serum cortisol levels.Results: There were no adverse events related to the selective use of cortisol replacement in this patient population. Conclusions: Our experience demonstrates that selective use of corticosteroid replacement is safe; it simplifies the management of the patients, and has advantages over empiric dogmatic steroid coverage.

  20. Peri-operative communication patterns and media usage--implications for systems design.

    Science.gov (United States)

    Karlsen, Ero S; Toussaint, Pieter Jelle

    2010-01-01

    Inter-hospital communication amounts for a great deal of clinicians' work time. While communication is essential to coordinate care, it can also be time consuming and interruptive, and breakdown in communication is an important source of medical errors. One contributor to the interruptive nature of communication is the use of synchronous media, and there is clearly a potential for novel technologies. To assess communication patterns and media usage we performed an ethnographic field study in the peri-operative environment at a Norwegian hospital, as well as interviews with nurses. We analyze the results with regards to choice of media, characteristics of the conversations taking place and meta-messages, and account for addressing, obtrusiveness and information richness in the message exchanges. We find a relative high degree of interruptiveness in communication, and ascribe it to 1) a lack of situational awareness between locations in the peri-operative domain, as well as 2) use of synchronous media. This suggests that design of novel technology for intra-hospital communication should aim at supporting sender-receiver awareness and signaling of availability.

  1. [Recommendations for the peri-operative management of bariatric surgery patients: results of a national survey].

    Science.gov (United States)

    Ortega, Joaquin; Cassinello, Norberto; Baltasar, Aniceto; Torres, Antonio J

    2012-01-01

    To standardise possible peri-operative bariatric surgery protocols, a survey was prepared to be filled in by members of the Spanish Society for Obesity (Sociedad Española de Cirugía de la Obesidad) (SECO), and to approve it at the XII National Congress. A total of 47 members of SECO from 14 autonomous communities responded, and it unanimously approved by the Congress. As highly recommended peri-operative procedures, were proposed: full laboratory analysis (98%) with an endocrine study (90%), ECG (96%), chest x-ray (98%), an oesophageal-gastric imaging test (endoscopy or gastro-duodenal transit study (98%), antibiotic prophylaxis (92%) and use of low molecular weight heparins pre-operatively (96%), and for 2 weeks (83%). Pre-surgical, abdominal ultrasound (86%), spirometry (80%), diet (88%) and psychological study (76%), and during surgery, use of elastic stockings (76%), leak tests (92%) and drainages (90%), were established as advisable procedures. Copyright © 2011 AEC. Published by Elsevier Espana. All rights reserved.

  2. Best practices in peri-operative management of patients with skeletal dysplasias.

    Science.gov (United States)

    White, Klane K; Bompadre, Viviana; Goldberg, Michael J; Bober, Michael B; Cho, Tae-Joon; Hoover-Fong, Julie E; Irving, Melita; Mackenzie, William G; Kamps, Shawn E; Raggio, Cathleen; Redding, Gregory J; Spencer, Samantha S; Savarirayan, Ravi; Theroux, Mary C

    2017-10-01

    Patients with skeletal dysplasia frequently require surgery. This patient population has an increased risk for peri-operative complications related to the anatomy of their upper airway, abnormalities of tracheal-bronchial morphology and function; deformity of their chest wall; abnormal mobility of their upper cervical spine; and associated issues with general health and body habitus. Utilizing evidence analysis and expert opinion, this study aims to describe best practices regarding the peri-operative management of patients with skeletal dysplasia. A panel of 13 multidisciplinary international experts participated in a Delphi process that included a thorough literature review; a list of 22 possible care recommendations; two rounds of anonymous voting; and a face to face meeting. Those recommendations with more than 80% agreement were considered as consensual. Consensus was reached to support 19 recommendations for best pre-operative management of patients with skeletal dysplasia. These recommendations include pre-operative pulmonary, polysomnography; cardiac, and neurological evaluations; imaging of the cervical spine; and anesthetic management of patients with a difficult airway for intubation and extubation. The goals of this consensus based best practice guideline are to provide a minimum of standardized care, reduce perioperative complications, and improve clinical outcomes for patients with skeletal dysplasia. © 2017 Wiley Periodicals, Inc.

  3. The peri-operative cytokine response in infants and young children following major surgery

    DEFF Research Database (Denmark)

    Hansen, Tom Giedsing; Tønnesen, Else Kirstine; Andersen, J B

    1998-01-01

    The peri-operative cytokine response was studied in 13 infants and young children undergoing major surgery. All children were anaesthetized with a combined general and epidural anaesthetic technique, followed by post-operative epidural analgesia with bupivacaine and fentanyl. Blood samples were...... taken before and after surgery, 24 h post-operatively, and finally, when the children were mobilized and had regained gastrointestinal function. Plasma samples were analysed for tumour necrosis factor-alpha, interleukin-1 alpha, interleukin-1 beta, interleukin-6, interferon-gamma, interleukin-10...... and the interleukin-1 receptor antagonist. The cytokine responses were highly variable. Overall, no significant changes between pre- and post-operative plasma concentrations were found. Tumour necrosis factor-alpha and the interleukin-1 receptor antagonist were detectable in all children, and a trend towards an early...

  4. Peri-operative glycaemic control regimens for preventing surgical site infections in adults.

    Science.gov (United States)

    Kao, Lillian S; Meeks, Derek; Moyer, Virginia A; Lally, Kevin P

    2009-07-08

    Surgical site infections (SSIs) are associated with significant morbidity, mortality, and resource utilization and are potentially preventable. Peri-operative hyperglycaemia has been associated with increased SSIs and previous recommendations have been to treat glucose levels above 200 mg/dL. However, recent studies have questioned the optimal glycaemic control regimen to prevent SSIs. Whether the benefits of strict or intensive glycaemic control with insulin infusion as compared to conventional management outweigh the risks remains controversial. To summarise the evidence for the impact of glycaemic control in the peri-operative period on the incidence of surgical site infections, hypoglycaemia, level of glycaemic control, all-cause and infection-related mortality, and hospital length of stay and to investigate for differences of effect between different levels of glycaemic control. A search strategy was developed to search the following databases: Cochrane Wounds Group Specialised Register (searched 25 March 2009), The Cochrane Central Register of Controlled Trials, The Cochrane Library 2009, Issue 1; Ovid MEDLINE (1950 to March Week 2 2009); Ovid EMBASE (1980 to 2009 Week 12) and EBSCO CINAHL (1982 to March Week 3 2009). The search was not limited by language or publication status. Randomised controlled trials (RCTs) were eligible for inclusion if they evaluated two (or more) glycaemic control regimens in the peri-operative period (within one week pre-, intra-, and/or post-operative) and reported surgical site infections as an outcome. The standard method for conducting a systematic review in accordance with the Cochrane Wounds Group was used. Two review authors independently reviewed the results from the database searches and identified relevant studies. Two review authors extracted study data and outcomes from each study and reviewed each study for methodological quality. Any disagreement was resolved by discussion or by referral to a third review author. Five

  5. Intensification of anxiety and depression, and personal resources among women during the peri-operative period

    Directory of Open Access Journals (Sweden)

    Magdalena Lewicka

    2014-03-01

    Full Text Available Aim. Surgical treatment of women due to gynaecological disorders is the cause of stress and may lead to psychological changes. Studies concerning human response to stress emphasize the importance of the effect of the level of the sense of coherence, anxiety, depression, dispositional optimism and skills of expressing emotions on the quality of feelings and experiences in difficult situations. Materials and methods. The study covered 232 women who had undergone gynaecological surgery due to various causes. Permission to conduct the research was obtained from the Bioethical Commission at the Medical University in Lublin. The study was carried out with the use of the State-Trait Anxiety Inventory (STAI, the Beck Depression Inventory, Courtauld Emotional Control Scale (CECS, and Life Orientation Test – Revised (LOT-R. Results and conclusions. The study showed that investigations of the sense of coherence, level of anxiety and depression, and personal resources allow determination of the characteristics of patients who should be covered with special psychoprophylactic care during the peri-operative period. In addition, the results of own studies obtained may be used for the development of adequate principles of psycho-prophylactic management in the course of the diagnostic-treatment proces with respect to women who had undergone surgical treatment due to gynaecological disorders.

  6. Nutrition for the pediatric surgical patient: approach in the peri-operative period

    Directory of Open Access Journals (Sweden)

    Falcão Mário Cícero

    2002-01-01

    Full Text Available Nutrition is essential for maintenance of physiologic homeostasis and growth. Hypermetabolic states lead to a depletion of body stores, with decreased immunocompetence and increased morbidity and mortality. The purpose of this paper is to provide an update regarding the provision of appropriate nutrition for the pediatric surgical patient, emphasizing the preoperative and postoperative periods. Modern nutritional support for the surgical patient comprises numerous stages, including assessment of nutritional status, nutritional requirements, and nutritional therapy. Nutritional assessment is performed utilizing the clinical history, clinical examination, anthropometry, and biochemical evaluation. Anthropometric parameters include body weight, height, arm and head circumference, and skinfold thickness measurements. The biochemical evaluation is conducted using determinations of plasma levels of proteins, including album, pre-albumin, transferrin, and retinol-binding protein. These parameters are subject to error and are influenced by the rapid changes in body composition in the peri-operative period. Nutritional therapy includes enteral and/or parenteral nutrition. Enteral feeding is the first choice for nutritional therapy. If enteral feeding is not indicated, parenteral nutrition must be utilized. In all cases, an individualized, adequate diet (enteral formula or parenteral solution is obligatory to decrease the occurrence of overfeeding and its undesirable consequences.

  7. Regional Differences in Case Mix and Peri-operative Outcome After Elective Abdominal Aortic Aneurysm Repair in the Vascunet Database.

    Science.gov (United States)

    Mani, K; Venermo, M; Beiles, B; Menyhei, G; Altreuther, M; Loftus, I; Björck, M

    2015-06-01

    National differences exist in the outcome of elective abdominal aortic aneurysm (AAA) repair. The role of case mix variation was assessed based on an international vascular registry collaboration. All elective AAA repairs with aneurysm size data in the Vascunet database in the period 2005-09 were included. AAA size and peri-operative outcome (crude and age adjusted mortality) were analysed overall and in risk cohorts, as well as per country. Glasgow Aneurysm Score (GAS) was calculated as risk score, and patients were stratified in three equal sized risk cohorts based on GAS. Predictors of peri-operative mortality were analysed with multiple regression. Missing data were handled with multiple imputation. Patients from Australia, Finland, Hungary, Norway, Sweden and the UK (n = 5,895) were analysed; mean age was 72.7 years and 54% had endovascular repair (EVAR). There were significant variations in GAS (lowest = Finland [75.7], highest = UK [79.4], p for comparison of all regions 82. Of those with a GAS >82, 8.4% of men and 20.8% of women had an AAA case selection for elective AAA repair, including variations in AAA size and patient risk profile. These differences partly explain the variations in peri-operative mortality. Further audit is warranted to assess the underlying reasons for the regional variation in case-mix. Copyright © 2015 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

  8. Modeling subsurface contamination at Fernald

    International Nuclear Information System (INIS)

    Jones, B.W.; Flinn, J.C.; Ruwe, P.R.

    1994-01-01

    The Department of Energy's Fernald site is located about 20 miles northwest of Cincinnati. Fernald produced refined uranium metal products from ores between 1953 and 1989. The pure uranium was sent to other DOE sites in South Carolina, Tennessee, Colorado,and Washington in support of the nation's strategic defense programs. Over the years of large-scale uranium production, contamination of the site's soil and groundwater occurred.The contamination is of particular concern because the Fernald site is located over the Great Miami Aquifer, a designated sole-source drinking water aquifer. Contamination of the aquifer with uranium was found beneath the site, and migration of the contamination had occurred well beyond the site's southern boundary. As a result, Fernald was placed on the National Priorities (CERCLA/Superfund) List in 1989. Uranium production at the site ended in 1989,and Fernald's mission has been changed to one of environmental restoration. This paper presents information about computerized modeling of subsurface contamination used for the environmental restoration project at Fernald

  9. Patterns in current anaesthesiological peri-operative practice for colonic resections: a survey in five northern-European countries

    DEFF Research Database (Denmark)

    Hannemann, P; Lassen, K; Hausel, J

    2006-01-01

    -acting anaesthetic medication may be beneficial. We examined whether these strategies have been adopted in five northern-European countries. METHODS: In 2003, a questionnaire concerning peri-operative anaesthetic routines in elective, open colonic cancer resection was sent to the chief anaesthesiologist in 258......-operative fasting, thoracic epidurals and short-acting anaesthetics. However, premedication with longer-acting agents is still common. Avoidance of fluid overload has not yet found its way into daily practice. This may leave patients undergoing elective colonic surgery at risk of oversedation and excessive fluid...

  10. Pulsed-dose-rate peri-operative brachytherapy as an interstitial boost in organ-sparing treatment of breast cancer

    Directory of Open Access Journals (Sweden)

    Krystyna Serkies

    2016-12-01

    Full Text Available Purpose : To evaluate peri-operative multicatheter interstitial pulsed-dose-rate brachytherapy (PDR-BT with an intra-operative catheter placement to boost the tumor excision site in breast cancer patients treated conservatively. Material and methods: Between May 2002 and October 2008, 96 consecutive T1-3N0-2M0 breast cancer patients underwent breast-conserving therapy (BCT including peri-operative PDR-BT boost, followed by whole breast external beam radiotherapy (WBRT. The BT dose of 15 Gy (1 Gy/pulse/h was given on the following day after surgery. Results: No increased bleeding or delayed wound healing related to the implants were observed. The only side effects included one case of temporary peri-operative breast infection and 3 cases of fat necrosis, both early and late. In 11 patients (11.4%, subsequent WBRT was omitted owing to the final pathology findings. These included eight patients who underwent mastectomy due to multiple adverse prognostic pathological features, one case of lobular carcinoma in situ, and two cases with no malignant tumor. With a median follow-up of 12 years (range: 7-14 years, among 85 patients who completed BCT, there was one ipsilateral breast tumor and one locoregional nodal recurrence. Six patients developed distant metastases and one was diagnosed with angiosarcoma within irradiated breast. The actuarial 5- and 10-year disease free survival was 90% (95% CI: 84-96% and 87% (95% CI: 80-94%, respectively, for the patients with invasive breast cancer, and 91% (95% CI: 84-97% and 89% (95% CI: 82-96%, respectively, for patients who completed BCT. Good cosmetic outcome by self-assessment was achieved in 58 out of 64 (91% evaluable patients. Conclusions : Peri-operative PDR-BT boost with intra-operative tube placement followed by EBRT is feasible and devoid of considerable toxicity, and provides excellent long-term local control. However, this strategy necessitates careful patient selection and histological confirmation

  11. Effects of intra-operative fluoroscopic 3D-imaging on peri-operative imaging strategy in calcaneal fracture surgery.

    Science.gov (United States)

    Beerekamp, M S H; Backes, M; Schep, N W L; Ubbink, D T; Luitse, J S; Schepers, T; Goslings, J C

    2017-12-01

    Previous studies demonstrated that intra-operative fluoroscopic 3D-imaging (3D-imaging) in calcaneal fracture surgery is promising to prevent revision surgery and save costs. However, these studies limited their focus to corrections performed after 3D-imaging, thereby neglecting corrections after intra-operative fluoroscopic 2D-imaging (2D-imaging). The aim of this study was to assess the effects of additional 3D-imaging on intra-operative corrections, peri-operative imaging used, and patient-relevant outcomes compared to 2D-imaging alone. In this before-after study, data of adult patients who underwent open reduction and internal fixation (ORIF) of a calcaneal fracture between 2000 and 2014 in our level-I Trauma center were collected. 3D-imaging (BV Pulsera with 3D-RX, Philips Healthcare, Best, The Netherlands) was available as of 2007 at the surgeons' discretion. Patient and fracture characteristics, peri-operative imaging, intra-operative corrections and patient-relevant outcomes were collected from the hospital databases. Patients in whom additional 3D-imaging was applied were compared to those undergoing 2D-imaging alone. A total of 231 patients were included of whom 107 (46%) were operated with the use of 3D-imaging. No significant differences were found in baseline characteristics. The median duration of surgery was significantly longer when using 3D-imaging (2:08 vs. 1:54 h; p = 0.002). Corrections after additional 3D-imaging were performed in 53% of the patients. However, significantly fewer corrections were made after 2D-imaging when 3D-imaging was available (Risk difference (RD) -15%; 95% Confidence interval (CI) -29 to -2). Peri-operative imaging, besides intra-operative 3D-imaging, and patient-relevant outcomes were similar between groups. Intra-operative 3D-imaging provides additional information resulting in additional corrections. Moreover, 3D-imaging probably changed the surgeons' attitude to rely more on 3D-imaging, hence a 15%-decrease of

  12. Free tissue transfer in patients with sickle cell disease: Considerations for multi-disciplinary peri-operative management.

    Science.gov (United States)

    Cooper, Lilli; Seth, Rohit; Rhodes, Elizabeth; Alousi, Mohammed; Sivakumar, Bran

    2017-01-01

    Sickle cell disease (SCD) is an increasingly common condition in the UK. The safety of free tissue transfer in these patients is controversial, and no specific guidelines exist. The aim of this paper is to create recommendations for the plastic surgical multidisciplinary team for use in the assessment and management of SCD patients undergoing free tissue transfer and reconstruction. A literature review was performed in PubMed of 'sickle [TiAb] AND plast* adj3 surg*. Sickle cell disease is explained, as is the relative peri-operative risk in different genotypes of SCD. Acute and chronic manifestations of SCD are described by system, for consideration at pre-operative assessment and post-operative review. The evidence surrounding free tissue transfer and SCD is discussed and the outcomes in published cases summarised. An algorithm for peri-operative multi-disciplinary management is outlined and justified. Free tissue transfer theoretically carries a high risk of a crisis, due not only to long anaesthetic times, but the potential requirement for tourniquet use, and the relatively hypoxic state of the transferred tissue. This paper outlines a useful, practical algorithm to optimise the safety of free tissue transfer in patients with SCD. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  13. Impact of spinal anaesthesia on peri-operative lung volumes in obese and morbidly obese female patients.

    Science.gov (United States)

    Regli, A; von Ungern-Sternberg, B S; Reber, A; Schneider, M C

    2006-03-01

    Although obesity predisposes to postoperative pulmonary complications, data on the relationship between body mass index (BMI) and peri-operative respiratory performance are limited. We prospectively studied the impact of spinal anaesthesia, obesity and vaginal surgery on lung volumes measured by spirometry in 28 patients with BMI 30-40 kg.m(-2) and in 13 patients with BMI > or = 40 kg.m(-2). Vital capacity, forced vital capacity, forced expiratory volume in 1 s, mid-expiratory and peak expiratory flows were measured during the pre-operative visit (baseline), after effective spinal anaesthesia with premedication, and after the operation at 20 min, 1 h, 2 h, and 3 h (after mobilisation). Spinal anaesthesia and premedication were associated with a significant decrease in spirometric parameters. Spinal anaesthesia and premedication were associated with a significant decrease in spirometric parameters; mean (SD) vital capacities were - 19% (6.4) in patients with BMI 30-40 kg.m(-2) and - 33% (9.0) in patients with BMI > 40 kg.m(-2). The decrease of lung volumes remained constant for 2 h, whereas 3 h after the operation and after mobilisation, spirometric parameters significantly improved in all patients. This study showed that both spinal anaesthesia and obesity significantly impaired peri-operative respiratory function.

  14. Nurse managers' decision-making in daily unit operation in peri-operative settings: a cross-sectional descriptive study.

    Science.gov (United States)

    Siirala, Eriikka; Peltonen, Laura-Maria; Lundgrén-Laine, Heljä; Salanterä, Sanna; Junttila, Kristiina

    2016-09-01

    To describe the tactical and the operational decisions made by nurse managers when managing the daily unit operation in peri-operative settings. Management is challenging as situations change rapidly and decisions are constantly made. Understanding decision-making in this complex environment helps to develop decision support systems to support nurse managers' operative and tactical decision-making. Descriptive cross-sectional design. Data were collected from 20 nurse managers with the think-aloud method during the busiest working hours and analysed using thematic content analysis. Nurse managers made over 700 decisions; either ad hoc (n = 289), near future (n = 268) or long-term (n = 187) by nature. Decisions were often made simultaneously with many interruptions. Ad hoc decisions covered staff allocation, ensuring adequate staff, rescheduling surgical procedures, confirmation tangible resources and following-up the daily unit operation. Decisions in the near future were: planning of surgical procedures and tangible resources, and planning staff allocation. Long-term decisions were: human recourses, nursing development, supplies and equipment, and finances in the unit. Decision-making was vulnerable to interruptions, which sometimes complicated the managing tasks. The results can be used when planning decision support systems and when defining the nurse managers' tasks in peri-operative settings. © 2016 John Wiley & Sons Ltd.

  15. [Injury to the Scapholunate Ligament in Distal Radius Fractures: Peri-Operative Diagnosis and Treatment Results].

    Science.gov (United States)

    Gajdoš, R; Pilný, J; Pokorná, A

    2016-01-01

    PURPOSE OF THE STUDY Injury to the scapholunate ligament is frequently associated with a fracture of the distal radius. At present neither a unified concept of treatment nor a standard method of diagnosis in these concomitant injuries is available. The aim of the study was to evaluate a group of surgically treated patients with distal radius fractures in order to assess a contribution of combined conventional X-ray and intra-operative fluoroscopic examinations to the diagnosis of associated lesions and to compare short-term functional outcomes of sugically treated patients with those of patients treated conservatively. MATERIAL AND METHODS A group of patients undergoiong surgery for distal radius fractures using plate osteosynthesis was evaluated retrospectively. The peri-operative diagnosis of associated injury to the scapholunate ligament was based on pre-operative standard X-ray views and intra-operative fluoroscopy. The latter consisted of images of maximum radial and ulnar deviation as well as an image of the forearm in traction exerted manually along the long axis. All views were in postero-anterior projection. Results were read directly on the monitor of a fluoroscopic device after its calibration or were obtained by comparing the thickness of an attached Kirschner wire with the distance to be measured. Subsequently, pixels were converted to millimetres. When a scapholunate ligament injury was found and confirmed by examination of the contralateral wrist, the finding was verified by open reduction or arthroscopy. Both static and dynamic instabilities were treated together with the distal radius fracture at one-stage surgery. After surgery, the patients without ligament injury had the wrist immobilised for 4 weeks, then rehabilitation followed. In the patients with a damaged ligament, immobilisation in a short brace lasted until transarticular wires were removed. All patients were followed up for a year at least. At follow-up, the injured wrist was examined

  16. Effect of different anesthesia methods on plasma neuropeptides levels during the peri-operative period in surgical patients with hypertension

    International Nuclear Information System (INIS)

    Li Hong; He Haomin; Tian Xiaoping

    2003-01-01

    Objective: To explore the effect of different anesthesia methods on the levels of plasma neuropeptides during the peri-operative period in patients with hypertension. Methods: Ninety hypertensive patients undergoing upper abdominal operations were randomly allocated to equal divided epidural anesthesia, general anesthesia and combined Groups. Plasma neuropeptide Y(NPY) concentrations were measured before anesthesia, at 15 min after anesthesia, 20 min after operation and 10 min after completion of the operation. Results: BP, HR and NPY were significantly changed in both E group and G group after anesthesia and operation (compared vs before anesthesia, p<0.01). BP, HR and NPY were significantly changed in C group after operation compared with those in both E and G group (p<0.05) . Conclusion: The combined anesthesia method is effective in inhibits the stress response during upper abdominal operation in the hypertensive patients

  17. Urban contamination and dose model

    International Nuclear Information System (INIS)

    Robertson, E.; Barry, P.J.

    1995-10-01

    Nuclear power reactors and other nuclear facilities are being built near or even within urban centres. Accidental releases of radionuclides to the atmosphere in built-up areas result in radiological exposure pathways that differ from those caused by releases in rural environments. Other than inhalation, exposure pathways involve external radiation from the plume while it passes and from radioactivity deposited onto the many and varied surfaces after it has passed. Radiation fields inside buildings are attenuated but many people are potentially exposed so while individual doses may be relatively low, population integrated doses may be high enough to cause concern. It is important, therefore, to assess the potential exposures and to estimate the cost-effectiveness of dose reduction measures in urban environments. This report describes a model developed to carry out such assessments. The model draws heavily on experience gained in European cities after their contamination fallout from the Chernobyl accident. Input is time integrated concentrations of specific radionuclides in urban air, obtained either by direct measurement or by prediction using an atmospheric dispersion model. The code includes default values for site specific variables and transfer parameters but the user is invited if desired to enter other values from the keyboard. Output is the time integrated dose rates for individuals selected because of the characteristic living, working and recreational habits. An accompanying manual documents the technical background on which the model is based and leads a first-time suer through various steps and operations encountered while the model is running. (author). 60 refs., 10 tabs., 1 fig

  18. Contaminant transport modeling studies of Russian sites

    International Nuclear Information System (INIS)

    Tsang, Chin-Fu

    1993-01-01

    Lawrence Berkeley Laboratory (LBL) established mechanisms that promoted cooperation between U.S. and Russian scientists in scientific research as well as environmental technology transfer. Using Russian experience and U.S technology, LBL developed approaches for field investigations, site evaluation, waste disposal, and remediation at Russian contaminated sites. LBL assessed a comprehensive database as well as an actual, large-scale contaminated site to evaluate existing knowledge of and test mathematical models used for the assessment of U.S. contaminated sites

  19. Use of peri-operative anti-epileptic drugs in patients with newly diagnosed high grade malignant glioma: a single center experience.

    Science.gov (United States)

    Lwu, Shelly; Hamilton, Mark G; Forsyth, Peter A; Cairncross, J Gregory; Parney, Ian F

    2010-02-01

    An American Academy of Neurology practice parameter recommends that long-term prophylactic anti-epileptic drugs (AED) should not be routine in patients with newly diagnosed brain tumors. However, prospective multi-center North American data shows that most newly diagnosed glioma patients receive prophylactic AED. We examined our own peri-operative AED practice patterns in newly-diagnosed patients with malignant glioma to determine if we deviate from published guidelines. A retrospective chart review was performed in adult patients with newly diagnosed malignant gliomas undergoing surgery in southern Alberta between January 2003 and December 2005. Demographic information, AED use, seizure incidence, adverse effects, tumor size, and tumor location were recorded. Of 164 eligible patients, 54 (33%) presented with seizures and all received AED. Prophylactic AED were given to 44 patients (27%). Peri-operative seizures (within 1 week) occurred in two patients without (3%) and no patients with seizure prophylaxis. Adverse AED reactions and adverse effects attributable to seizures were both rare. Prophylactic AED were continued >1 week post-op in 30 patients (18%). Patients receiving prophylactic AED were more likely to have had tumors involving the temporal lobe than those who did not (50 vs. 20%; P < 0.01). Patients receiving peri-operative AED prophylaxis were common, had a trend to reduced peri-operative seizures, and had few adverse effects. However, most of these patients were maintained on prophylactic AED continued beyond the first peri-operative week, contradicting published guidelines. Increased awareness of practice guidelines may help modify AED prescription patterns in malignant glioma patients.

  20. ARSENIC CONTAMINATION IN GROUNDWATER: A STATISTICAL MODELING

    Directory of Open Access Journals (Sweden)

    Palas Roy

    2013-01-01

    Full Text Available High arsenic in natural groundwater in most of the tubewells of the Purbasthali- Block II area of Burdwan district (W.B, India has recently been focused as a serious environmental concern. This paper is intending to illustrate the statistical modeling of the arsenic contaminated groundwater to identify the interrelation of that arsenic contain with other participating groundwater parameters so that the arsenic contamination level can easily be predicted by analyzing only such parameters. Multivariate data analysis was done with the collected groundwater samples from the 132 tubewells of this contaminated region shows that three variable parameters are significantly related with the arsenic. Based on these relationships, a multiple linear regression model has been developed that estimated the arsenic contamination by measuring such three predictor parameters of the groundwater variables in the contaminated aquifer. This model could also be a suggestive tool while designing the arsenic removal scheme for any affected groundwater.

  1. Determinants of peri-operative blood transfusion in a contemporary series of open prostatectomy for benign prostate hyperplasia.

    Science.gov (United States)

    Kyei, Mathew Y; Klufio, George O; Mensah, James E; Gepi-Attee, Samuel; Ampadu, Kwabena; Toboh, Bernard; Yeboah, Edward D

    2016-03-28

    The objective of this study was to determine the factors responsible for peri-operative blood transfusion in a contemporary series of open prostatectomy for benign prostate hyperplasia and thus offer a guide for blood product management for the procedure. This was a prospective study of 200 consecutive patients who underwent open prostatectomy for BPH from January 2010 to September 2013 at the Korle Bu Teaching Hospital, Accra. The data analyzed included the pre-operative blood haemoglobin level (Hb), presence of co-morbidities, the case type, indication for the surgery, ASA score, anaesthetic method used, systolic blood pressure, status of the operating surgeon, duration of surgery and the operative prostate weight. The transfusion of blood peri-operatively was also documented. The mean age of the patients was 69.1 years. Elective cases formed 83.5 % with refractory retention of urine being the commonest indication for surgery (68.0 %). The mean pre-operative Hb was 12.1 g/dl. Consultants performed 56.0 % of the prostatectomies. Transvesical approach was used in 90.0 % of the cases. The mean operative time was 101.3mins (range 35.0-240.0) with a mean operative prostate weight of 110.8 g (range 15-550 g). Most of the patients (82.0 %) had spinal anaesthesia. The blood transfusion rate was 23.5 %. The transfusion rate was significantly higher in patients with anaemia (p = .000), emergency cases (p = .000), the use of general anaesthesia (p = .002), a resident as the operating surgeons (p = .034), prostate weight >100 g (p = .000) and duration of surgery (p = .011). In a multivariable logistic regression analysis however only the pre-operative Hb (p = .000. OR 0.95, 95 % CI [0.035-0.257]) and the duration of surgery (p = .025, OR 1.021, 95 % CI [1.003-1.039]) could predict blood transfusion in open prostatectomy for BPH in this series. A 'group and save' policy should be the preferred blood ordering procedure for patients

  2. Centrifuge modelling of contaminant transport processes

    OpenAIRE

    Culligan, P. J.; Savvidou, C.; Barry, D. A.

    1996-01-01

    Over the past decade, research workers have started to investigate problems of subsurface contaminant transport through physical modelling on a geotechnical centrifuge. A major advantage of this apparatus is its ability to model complex natural systems in a controlled laboratory environment In this paper, we discusses the principles and scaling laws related to the centrifugal modelling of contaminant transport, and presents four examples of recent work that has bee...

  3. Molecular contamination math model support

    Science.gov (United States)

    Wells, R.

    1983-01-01

    The operation and features of a preprocessor for the Shuttle/Payload Contamination Evaluation Program Version 2) are described. A preliminary preprocessor for SPACE 2 is developed. Further refinements and enhancements of the preprocessor to insure complete user friendly operation, are recommended.

  4. Differences between patients' and clinicians' research priorities from the Anaesthesia and Peri-operative Care Priority Setting Partnership.

    Science.gov (United States)

    Boney, O; Nathanson, M H; Grocott, M P W; Metcalf, L

    2017-09-01

    The James Lind Alliance Anaesthesia and Peri-operative Care Priority Setting Partnership was a recent collaborative venture bringing approximately 2000 patients, carers and clinicians together to agree priorities for future research into anaesthesia and critical care. This secondary analysis compares the research priorities of 303 service users, 1068 clinicians and 325 clinicians with experience as service users. All three groups prioritised research to improve patient safety. Service users prioritised research about improving patient experience, whereas clinicians prioritised research about clinical effectiveness. Clinicians who had experience as service users consistently prioritised research more like clinicians than like service users. Individual research questions about patient experience were more popular with patients and carers than with clinicians in all but one case. We conclude that patients, carers and clinicians prioritise research questions differently. All groups prioritise research into patient safety, but service users also favour research into patient experience, whereas clinicians favour research into clinical effectiveness. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

  5. Preliminary audiologic and peri-operative outcomes of the Sophono™ transcutaneous bone conduction device: A systematic review.

    Science.gov (United States)

    Bezdjian, Aren; Bruijnzeel, Hanneke; Daniel, Sam J; Grolman, Wilko; Thomeer, Hans G X M

    2017-10-01

    To delineate the auditory functional improvement and peri-operative outcomes of the Sophono™ transcutaneous bone conduction device. Eligible articles presenting patients implanted with the Sophono™ were identified through a comprehensive search of PubMed and Embase electronic databases. All relevant articles were reviewed to justify inclusion independently by 2 authors. Studies that successfully passed critical appraisal for directness of evidence and risk of bias were included. From a total of 125 articles, 8 studies encompassing 86 patients using 99 implants were selected. Most patients (79.1%) were children. Ear atresia (67.5%) was the most frequently reported indication for Sophono™ implantation. Overall pure tone average auditory improvement was 31.10 (±8.29) decibel. During a mean follow-up time of 12.48 months, 25 patients (29%) presented with post-operative complications from which 3 were deemed as serious implant-related adverse events (3.5%). The Sophono™ transcutaneous bone conduction device shows promising functional improvement, no intra-operative complications and minor post-operative skin related complications. If suitable, the device could be a proposed solution for the rehabilitation of hearing in children meeting eligibility criteria. A wearing schedule must be implemented in order to reduce magnet-related skin complications. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Modeling contaminant plumes in fractured limestone aquifers

    DEFF Research Database (Denmark)

    Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika Sidelmann

    Determining the fate and transport of contaminant plumes from contaminated sites in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules, resulting in a complex transport...... model. The paper concludes with recommendations on how to identify and employ suitable models to advance the conceptual understanding and as decision support tools for risk assessment and the planning of remedial actions....... behavior. Improved conceptual models are needed for this type of site. Here conceptual models are developed by combining numerical models with field data. Several types of fracture flow and transport models are available for the modeling of contaminant transport in fractured media. These include...... the established approaches of the equivalent porous medium, discrete fracture and dual continuum models. However, these modeling concepts are not well tested for contaminant plume migration in limestone geologies. Our goal was to develop and evaluate approaches for modeling the transport of dissolved contaminant...

  7. ARSENIC CONTAMINATION IN GROUNDWATER: A STATISTICAL MODELING

    OpenAIRE

    Palas Roy; Naba Kumar Mondal; Biswajit Das; Kousik Das

    2013-01-01

    High arsenic in natural groundwater in most of the tubewells of the Purbasthali- Block II area of Burdwan district (W.B, India) has recently been focused as a serious environmental concern. This paper is intending to illustrate the statistical modeling of the arsenic contaminated groundwater to identify the interrelation of that arsenic contain with other participating groundwater parameters so that the arsenic contamination level can easily be predicted by analyzing only such parameters. Mul...

  8. Peri-operative antibiotic treatment of bacteriuria reduces early deep surgical site infections in geriatric patients with proximal femur fracture.

    Science.gov (United States)

    Langenhan, Ronny; Bushuven, Stefanie; Reimers, Niklas; Probst, Axel

    2018-04-01

    The aim of this study was to conduct a re-evaluation of current strategies for peri-operative prophylaxis of infections in orthopaedic surgery of geriatric patients (≥65 years) with proximal femoral fractures (PFF). Between 01/2010 and 08/2014 all post-operative infections after stabilization of PFF of 1,089 geriatric patients were recorded retrospectively. All patients pre-operatively received a single dose of 1.5 g cefuroxime (group 1). These were compared to prospectively determined post-operative rates of surgical site infection (SSI) of 441 geriatric patients, which were operated on between 09/2014 and 03/2017 due to PFF. In this second group we investigated the urinary tract on admission. Bacteriuria was treated with the pre-operative single dose of 1.5 g cefuroxime along with ciprofloxacin for five days, beginning on admission. Level of significance was set to p infection. Multi-resistant pathogens were found in 15 patients and pathogens were cefuroxime-resistant in 37. The differences of SSI after at least three months were 2.1% in group 1 and 0.45% in group 2 for all patients with surgery of PFF (p < 0.02) and for those with arthroplasty (p < 0.037) significant. The immediate antibiotic therapy of a prevalent bacteriuria for five days decreases the risk of SSI after surgery of PFF. Our single-centre study can only point out the problem of prevalent reservoirs of pathogens and the need for treatment. Evidence-based therapy concepts (indications of antibiotics, classes, duration) have to be developed in multi-centric and prospective studies.

  9. Use and Effectiveness of Peri-Operative Cefotetan versus Cefazolin Plus Metronidazole for Prevention of Surgical Site Infection in Abdominal Surgery Patients.

    Science.gov (United States)

    Danan, Eleanor; Smith, Janessa; Kruer, Rachel M; Avdic, Edina; Lipsett, Pamela; Curless, Melanie S; Jarrell, Andrew S

    2018-04-24

    Current practice guidelines for antimicrobial prophylaxis in surgery recommend a cephamycin or cefazolin plus metronidazole for various abdominal surgeries. In February 2016, cephamycin drug shortages resulted in a change in The Johns Hopkins Hospital's (JHH) recommendation for peri-operative antibiotic prophylaxis in abdominal surgeries from cefotetan to cefazolin plus metronidazole. The primary objective of this study was to quantify the percentage of abdominal surgeries adherent to JHH peri-operative antibiotic prophylaxis guidelines. A sub-group analysis investigated whether prophylaxis with cefazolin plus metronidazole was associated with a lower rate of surgical site infections (SSIs) versus cefotetan. This retrospective cohort study included adult inpatients who underwent an abdominal surgery at JHH in September 2015 (Study Period I: cefotetan) or February to March 2016 (Study Period II: cefazolin plus metronidazole). Two hundred abdominal surgery cases were included in the primary analysis. A subset of 156 surgical cases were included in the sub-group analysis. The overall adherence rate to JHH guidelines was 75% in Study Period I versus 17% in Study Period II (p operative administration time (87% vs. 23%, p site infections occurred in 14% (12/83) of surgeries with cefotetan versus 8.2% (6/73) with cefazolin plus metronidazole for prophylaxis (p = 0.19). Adherence to an institution-specific peri-operative antibiotic prophylaxis guideline for abdominal surgeries was limited primarily by the longer infusion time required for pre-operative metronidazole. A higher percentage of SSIs occurred among abdominal surgeries with cefotetan versus cefazolin plus metronidazole for prophylaxis.

  10. Modeling bacterial contamination of fuel ethanol fermentation.

    Science.gov (United States)

    Bischoff, Kenneth M; Liu, Siqing; Leathers, Timothy D; Worthington, Ronald E; Rich, Joseph O

    2009-05-01

    The emergence of antibiotic-resistant bacteria may limit the effectiveness of antibiotics to treat bacterial contamination in fuel ethanol plants, and therefore, new antibacterial intervention methods and tools to test their application are needed. Using shake-flask cultures of Saccharomyces cerevisiae grown on saccharified corn mash and strains of lactic acid bacteria isolated from a dry-grind ethanol facility, a simple model to simulate bacterial contamination and infection was developed. Challenging the model with 10(8) CFU/mL Lactobacillus fermentum decreased ethanol yield by 27% and increased residual glucose from 6.2 to 45.5 g/L. The magnitude of the effect was proportional to the initial bacterial load, with 10(5) CFU/mL L. fermentum still producing an 8% decrease in ethanol and a 3.2-fold increase in residual glucose. Infection was also dependent on the bacterial species used to challenge the fermentation, as neither L. delbrueckii ATCC 4797 nor L. amylovorus 0315-7B produced a significant decrease in ethanol when inoculated at a density of 10(8) CFU/mL. In the shake-flask model, treatment with 2 microg/mL virginiamycin mitigated the infection when challenged with a susceptible strain of L. fermentum (MIC for virginiamycin model may find application in developing new antibacterial agents and management practices for use in controlling contamination in the fuel ethanol industry. Copyright 2008 Wiley Periodicals, Inc.

  11. Modeling electrokinetic transport in phenol contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Zorn, R.; Haus, R.; Czurda, K. [Dept. of Applied Geology, Univ. Karlsruhe (Germany)

    2001-07-01

    Numerical simulations are compared to laboratory experiments of electroremediation in soils contaminated by phenolic pollutants. The developing pH affects the electrokinetic transport behaviour of phenol. It is found that a water chemistry model must be included in an electrokinetic mass transport model to describe the process of electroremediation more accurately, if no buffering system is used at the electrodes. In the case of controlling the pH at the electrode compartments only a simplified chemical reaction model must be included in the numerical code to match the experimental phenolic transport. (orig.)

  12. In vitro study of transmission of bacteria from contaminated metal models to stone models via impressions

    DEFF Research Database (Denmark)

    Sofou, A.; Larsen, T.; Öwall, B.

    2002-01-01

    Dental impression, stone model, bacterial contamination, cross-infection, dental clinic, dental laboratory......Dental impression, stone model, bacterial contamination, cross-infection, dental clinic, dental laboratory...

  13. Interaction between peri-operative blood transfusion, tidal volume, airway pressure and postoperative ARDS: an individual patient data meta-analysis.

    Science.gov (United States)

    Serpa Neto, Ary; Juffermans, Nicole P; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Biehl, Michelle; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; Jaber, Samir; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Memtsoudis, Stavros G; Miranda, Dinis Reis; Moine, Pierre; Paparella, Domenico; Ranieri, Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

    2018-01-01

    Transfusion of blood products and mechanical ventilation with injurious settings are considered risk factors for postoperative lung injury in surgical Patients. A systematic review and individual patient data meta-analysis was done to determine the independent effects of peri-operative transfusion of blood products, intra-operative tidal volume and airway pressure in adult patients undergoing mechanical ventilation for general surgery, as well as their interactions on the occurrence of postoperative acute respiratory distress syndrome (ARDS). Observational studies and randomized trials were identified by a systematic search of MEDLINE, CINAHL, Web of Science, and CENTRAL and screened for inclusion into a meta-analysis. Individual patient data were obtained from the corresponding authors. Patients were stratified according to whether they received transfusion in the peri-operative period [red blood cell concentrates (RBC) and/or fresh frozen plasma (FFP)], tidal volume size [≤7 mL/kg predicted body weight (PBW), 7-10 and >10 mL/kg PBW] and airway pressure level used during surgery (≤15, 15-20 and >20 cmH 2 O). The primary outcome was development of postoperative ARDS. Seventeen investigations were included (3,659 patients). Postoperative ARDS occurred in 40 (7.2%) patients who received at least one blood product compared to 40 patients (2.5%) who did not [adjusted hazard ratio (HR), 2.32; 95% confidence interval (CI), 1.25-4.33; P=0.008]. Incidence of postoperative ARDS was highest in patients ventilated with tidal volumes of >10 mL/kg PBW and having airway pressures of >20 cmH 2 O receiving both RBC and FFP, and lowest in patients ventilated with tidal volume of ≤7 mL/kg PBW and having airway pressures of ≤15 cmH 2 O with no transfusion. There was a significant interaction between transfusion and airway pressure level (P=0.002) on the risk of postoperative ARDS. Peri-operative transfusion of blood products is associated with an increased risk of

  14. Changes of serum cortisol and plasma angiotensin-II (AT-II) levels in patients with open chest surgery during peri-operative stage

    International Nuclear Information System (INIS)

    Yu Yunyun; Tian Runhua; Zhao Huiyuan; Li Xiaoqin; Wang Ling

    2005-01-01

    Objective: To assess the systemic stress reaction in patients with open chest surgery through measurement of the changes of serum cortisol and plasma AT-II levels during peri-operative stage. Methods: Serum cortisol and plasma AT-II levels were measured with RIA in 35 patients underwent open chest surgery both before and after the operative procedure. Results: The serum level of cortisol and plasma levels of AT-II were significantly higher after operation than those before operation ( P < 0.05 ). Also, the systolic pressure and heart rate were increased significantly (P<0.05). The post-operative heart rate was significantly positively correlated with both cortisol and AT-II levels (P<0.05). Conclusion: Stress reaction is evident in patients after open chest surgery with increase of serum cortisol and plasma AT-II levels. The stress reaction, if excessive, should be properly dealt with. (authors)

  15. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

    Onishi, Y.; Mayer, D.W.; Argo, R.S.

    1982-02-01

    A hydrodynamic model, CAFE-I, a wave refraction model, LO3D, and a sediment and contaminant transport model, FETRA, were selected as tools for evaluating exposure levels of radionuclides, heavy metals, and other toxic chemicals in coastal waters. Prior to the application of these models to the Irish Sea and other coastal waters, the finite element model, FETRA, was tested to demonstrate its ability to simulate sediment and contaminant interactions (e.g., adsorption and desorption), and the mechanisms governing the transport, deposition, and resuspension of contaminated sediments

  16. Modelling of contamination of surface atmosphere for deflation of Cesium-137 on contaminated territories

    International Nuclear Information System (INIS)

    Bogdanov, A.P.; Zhmura, G.M.

    1994-01-01

    Presence of Cesium 137 in near land air is caused at the contaminated territories by 'local' dusting and transport of the dust from the zone of strong contamination. For large distance is it caused by resuspension of radioactive dust from the surface in the given region. In accordance with the models of dusting round square sources based on Gauss statistical model of dissemination of admixtures in the atmosphere, the contaminated areas of european part of the former of USSR with the density of contamination over 1 Ci/km 2 with Cesium 137 were represented by 30 round square sources covering the main spots of contamination. The results of calculation of contamination of the atmosphere for several cities of Belarus, Russia and Ukraine, where there are the permanent points of observation for the content of radionuclides in the air, have shown that the proposed model of dusting sources describes the contamination of near land air with Cesium 137 reasonably well. 7 refs., 3 tabs

  17. Preemptive carprofen for peri-operative analgesia in dogs undergoing Tibial Plateau Leveling Osteotomy (TPLO): a prospective, randomized, blinded, placebo controlled clinical trial.

    Science.gov (United States)

    Bufalari, A; Maggio, C; Cerasoli, I; Morath, U; Adami, C

    2012-03-01

    Eighteen client-owned dogs undergoing Tibial Plateau Leveling Osteotomy (TPLO) were included in this blinded clinical study and randomly assigned to one of two treatment groups. Group C (carprofen) received intravenous (IV) carprofen, 4 mg/kg, prior to anesthesia, whereas group P (placebo) received IV saline. General anesthesia was maintained with isoflurane in oxygen and a constant rate infusion (CRI) of sufentanyl IV. Intra-operatively, assessment of nociception was based on changes in physiological parameters and on the analgesics requirement, whereas in the post-operative period evaluation of pain was performed by using a Hellyer and Gaynor pain score and by comparing the doses of rescue buprenorphine required by the two treatment groups. Although no statistically significant differences in intra-operative sufentanyl doses were found between treatment groups, group C had superior cardiovascular stability, and lower post-operative pain scores and rescue buprenorphine doses than group P. Our results indicate that administration of carprofen prior to surgery was effective in improving peri-operative analgesia in dogs undergoing TPLO.

  18. Peri-operative oral caffeine does not prevent postoperative atrial fibrillation after heart valve surgery with cardiopulmonary bypass: A randomised controlled clinical trial.

    Science.gov (United States)

    Lagier, David; Nee, Laetitia; Guieu, Régis; Kerbaul, François; Fenouillet, Emmanuel; Roux, Nicolas; Giorgi, Roch; Theron, Alexis; Grisoli, Dominique; Gariboldi, Vlad; Collart, Frederic; Bruder, Nicolas; Velly, Lionel; Guidon, Catherine

    2018-04-26

    Raised plasma levels of endogenous adenosine after cardiac surgery using cardiopulmonary bypass (CPB) have been related to the incidence of postoperative atrial fibrillation (POAF). We wished to assess if caffeine, an adenosine receptor antagonist could have a beneficial effect on the incidence of POAF. A randomised controlled study. Single University Hospital. One hundred and ten patients scheduled for heart valve surgery with CPB. We randomly assigned patients to receive peri-operative oral caffeine (400 mg every 8 h for 2 days) or placebo. Adenosine plasma concentrations and caffeine pharmacokinetic profile were evaluated in a subgroup of 50 patients. The primary endpoint was the rate of atrial fibrillation during postoperative hospital stay. The current study was stopped for futility by the data monitoring board after an interim analysis. The incidence of atrial fibrillation was similar in the caffeine and in the placebo group during hospital stay (33 vs. 29%, P = 0.67) and the first 3 postoperative days (18 vs. 15%; P = 0.60). Basal and postoperative adenosine plasma levels were significantly associated with the primary outcome. Adenosine plasma levels were similar in the two treatment groups. Caffeine administration was associated with a higher incidence of postoperative nausea and vomiting (27 vs. 7%, P = 0.005). Oral caffeine does not prevent POAF after heart valve surgery with CPB but increased the incidence of postoperative nausea and vomiting. ClinicalTrials.gov, no.: NCT01999829.

  19. Changes of plasma IL-6 and TNF-α levels during peri-operative period in patients undergoing laser photo-coagulation of greater saphenous varicosities

    International Nuclear Information System (INIS)

    Wang Taihan; Wang Chunxi

    2005-01-01

    Objective: To investigate the plasma levels of IL-6 and TNF-α during peri-operative period in patients undergoing laser photocoagulation of greater saphenous varicosities. Methods: Plasma IL-6 and TNF-α levels were determined with RIA before operation and 1, 3, 7, 14 days post-operatively in 110 patients with greater saphenous vein varicosity undergoing different forms of treatment (intravascular laser photo-coagulation 43, photo-coagulation combined with venous valve repair 35, high ligation and segmental stripping 32). Skin trophic disturbances were present in 56 of the 110 patients. Plasma IL-6 and TNF-α levels were also measured in 33 controls. Results: The plasma IL-6 and TNF-α levels in patients with skin trophic disturbances were significantly higher than those in controls (P<0.01), while levels in patients without skin lesions were not much changed. The plasma IL-6 and TNF-α levels were increased at first and dropped later to approaching pre-operative value by d14 in all the 110 patients after operation, however, the amount of increase was least and the normalization was also soonest in the simple photo-coagulation group, the reverse was true for the conventional operation group. Conclusion: Laser photo-coagulation is least stressful among the three types of operation and magnitude of changes of plasma IL-6 and TNF-α levels correctly reflects the intensity of stress. (authors)

  20. Computer modelling of contaminant migration in natural disperse media

    International Nuclear Information System (INIS)

    Kundas, S.P.; Gishkelyuk, I.A.; Khil'ko, O.S.

    2012-01-01

    The theoretical foundations for modeling of the contaminants migration in natural disperses media taking into account interconnected heat and moisture transport are developed. The calculation of mass transfer parameters based on adsorption isotherms of water and thermodynamic equations in the developed mathematical models. The artificial neural networks use to predict migration of contaminants in natural disperse media is proposed. The developed software package is presented and results of practical application of models and software are discussed. (authors)

  1. ESI nuclear model 271 C contamination monitor

    International Nuclear Information System (INIS)

    Burgess, P.H.; Iles, W.J.

    1978-06-01

    This instrument is a general purpose contamination monitor, comprising a GM tube connected by a coiled extensible cable to a ratemeter. The scale is marked quasi-logarithmically from 0 to 600 in 'counts per second'. The report falls under the headings: general description, facilities and controls, radiation performance, electrical characteristics, environmental characteristics, mechanical characteristics, summary of performance, conclusions. (U.K.)

  2. Simulation–optimization model for groundwater contamination ...

    Indian Academy of Sciences (India)

    used techniques for groundwater remediation in which the contaminated groundwater is pumped ... ing the affected groundwater aquifer down to some drinking water standard. Several .... For simplicity, rectangular support domain is used in this study. Figure 1 ..... For PAT remediation system, decision variables include the.

  3. Comparative study of surrogate models for groundwater contamination source identification at DNAPL-contaminated sites

    Science.gov (United States)

    Hou, Zeyu; Lu, Wenxi

    2018-05-01

    Knowledge of groundwater contamination sources is critical for effectively protecting groundwater resources, estimating risks, mitigating disaster, and designing remediation strategies. Many methods for groundwater contamination source identification (GCSI) have been developed in recent years, including the simulation-optimization technique. This study proposes utilizing a support vector regression (SVR) model and a kernel extreme learning machine (KELM) model to enrich the content of the surrogate model. The surrogate model was itself key in replacing the simulation model, reducing the huge computational burden of iterations in the simulation-optimization technique to solve GCSI problems, especially in GCSI problems of aquifers contaminated by dense nonaqueous phase liquids (DNAPLs). A comparative study between the Kriging, SVR, and KELM models is reported. Additionally, there is analysis of the influence of parameter optimization and the structure of the training sample dataset on the approximation accuracy of the surrogate model. It was found that the KELM model was the most accurate surrogate model, and its performance was significantly improved after parameter optimization. The approximation accuracy of the surrogate model to the simulation model did not always improve with increasing numbers of training samples. Using the appropriate number of training samples was critical for improving the performance of the surrogate model and avoiding unnecessary computational workload. It was concluded that the KELM model developed in this work could reasonably predict system responses in given operation conditions. Replacing the simulation model with a KELM model considerably reduced the computational burden of the simulation-optimization process and also maintained high computation accuracy.

  4. Inexact Socio-Dynamic Modeling of Groundwater Contamination Management

    Science.gov (United States)

    Vesselinov, V. V.; Zhang, X.

    2015-12-01

    Groundwater contamination may alter the behaviors of the public such as adaptation to such a contamination event. On the other hand, social behaviors may affect groundwater contamination and associated risk levels such as through changing ingestion amount of groundwater due to the contamination. Decisions should consider not only the contamination itself, but also social attitudes on such contamination events. Such decisions are inherently associated with uncertainty, such as subjective judgement from decision makers and their implicit knowledge on selection of whether to supply water or reduce the amount of supplied water under the scenario of the contamination. A socio-dynamic model based on the theories of information-gap and fuzzy sets is being developed to address the social behaviors facing the groundwater contamination and applied to a synthetic problem designed based on typical groundwater remediation sites where the effects of social behaviors on decisions are investigated and analyzed. Different uncertainties including deep uncertainty and vague/ambiguous uncertainty are effectively and integrally addressed. The results can provide scientifically-defensible decision supports for groundwater management in face of the contamination.

  5. Radiative Transfer Model for Contaminated Rough Surfaces

    Science.gov (United States)

    2013-02-01

    reflectance of potassium chlorate and ammonium nitrate contaminated surfaces in mid-wavelength and long-wavelength infrared for detection. Our framework...obtained excellent or good results for lab measurements of potassium chlorate on most aluminum surfaces; however, ammonium nitrate on painted aluminum...misidentify potassium chlorate as ammonium nitrate and vice versa). We also observed moderate success on field data. 15. SUBJECT TERMS radiative

  6. A survey of contemporary opinions and practices of surgical and intensive care specialists towards peri-operative venous thromboembolism prophylaxis in Asia.

    Science.gov (United States)

    Lee, L; Liew, N C; Gee, T

    2012-12-01

    This survey was conducted to determine the opinions and practices of peri-operative venous thromboembolism (VTE) prophylaxis among surgical and intensive care specialists in Asia. A set of questionnaire was distributed to surgeons and intensivists from different countries in Asia. The specialties included were general surgery and its sub-specialties, orthopaedic surgery, gynaecological surgery and intensive care unit. This survey involved teaching institutions, general hospitals and private hospitals. To gauge if the respondents were from hospitals that would likely encounter VTE cases, the hospital's bed-strength, intensive care facility and sub-specialty services were recorded. Over a period of six months, questionnaires and feedbacks were collected and analyzed. One hundred and ninety-one responses were received from 8 countries throughout Asia. Fifty-six percent of these were from large hospitals (800 bedded or more) and 62% of these hospitals have large intensive care facility (20 or more beds). Only half of the respondents practice routine thromboprophylaxis in moderate and high risk surgeries. Thirty six percent of them practices selective thromboprophylaxis and only 3% do not believe in any thromboprophylaxis. A third prescribed thromboprophylaxis for 3 to 5 days; another third extended it until patient is mobile. About 48.6% of the respondents do not have VTE guidelines in their institutions. Majority of the respondents agreed that more evidence is needed in the form of multi-centre randomized controlled trials to influence their decision on thromboprophylaxis. Despite the availability of strong epidemiological data, randomized controlled trials and multicentre case-controlled studies, perioperative VTE prophylactic practices are still suboptimal in Asia.

  7. Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants

    Science.gov (United States)

    Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

    1998-01-01

    Control of air contaminants is a crucial factor in the safety considerations of crewed space flight. Indoor air quality needs to be closely monitored during long range missions such as a Mars mission, and also on large complex space structures such as the International Space Station. This work mainly pertains to the detection and simulation of air contaminants in the space station, though much of the work is easily extended to buildings, and issues of ventilation systems. Here we propose a method with which to track the presence of contaminants using an accurate physical model, and also develop a robust procedure that would raise alarms when certain tolerance levels are exceeded. A part of this research concerns the modeling of air flow inside a spacecraft, and the consequent dispersal pattern of contaminants. Our objective is to also monitor the contaminants on-line, so we develop a state estimation procedure that makes use of the measurements from a sensor system and determines an optimal estimate of the contamination in the system as a function of time and space. The real-time optimal estimates in turn are used to detect faults in the system and also offer diagnoses as to their sources. This work is concerned with the monitoring of air contaminants aboard future generation spacecraft and seeks to satisfy NASA's requirements as outlined in their Strategic Plan document (Technology Development Requirements, 1996).

  8. Modeling of laser damage initiated by surface contamination

    International Nuclear Information System (INIS)

    Feit, M.D.; Rubenchik, A.M.; Faux, D.R.; Riddle, R.A.; Shapiro, A.; Eder, D.C.; Penetrante, B.M.; Milam, D.; Genin, F.Y.; Kozlowski, M.R.

    1996-11-01

    The authors are engaged in a comprehensive effort to understand and model the initiation and growth of laser damage initiated by surface contaminants. This includes, for example, the initial absorption by the contaminant, heating and plasma generation, pressure and thermal loading of the transparent substrate, and subsequent shockwave propagation, 'splashing' of molten material and possible spallation, optical propagation and scattering, and treatment of material fracture. The integration use of large radiation hydrodynamics codes, optical propagation codes and material strength codes enables a comprehensive view of the damage process The following picture of surface contaminant initiated laser damage is emerging from our simulations

  9. Software for modelling groundwater transport and contaminant migration

    International Nuclear Information System (INIS)

    Gishkelyuk, I.A.

    2008-01-01

    Facilities of modern software for modeling of groundwater transport and process of contaminant distribution are considered. Advantages of their application are discussed. The comparative analysis of mathematical modeling software of 'Groundwater modeling system' and 'Earth Science Module' from 'COMSOL Multiphysics' is carried out. (authors)

  10. Low-Rank Kalman Filtering in Subsurface Contaminant Transport Models

    KAUST Repository

    El Gharamti, Mohamad

    2010-12-01

    Understanding the geology and the hydrology of the subsurface is important to model the fluid flow and the behavior of the contaminant. It is essential to have an accurate knowledge of the movement of the contaminants in the porous media in order to track them and later extract them from the aquifer. A two-dimensional flow model is studied and then applied on a linear contaminant transport model in the same porous medium. Because of possible different sources of uncertainties, the deterministic model by itself cannot give exact estimations for the future contaminant state. Incorporating observations in the model can guide it to the true state. This is usually done using the Kalman filter (KF) when the system is linear and the extended Kalman filter (EKF) when the system is nonlinear. To overcome the high computational cost required by the KF, we use the singular evolutive Kalman filter (SEKF) and the singular evolutive extended Kalman filter (SEEKF) approximations of the KF operating with low-rank covariance matrices. The SEKF can be implemented on large dimensional contaminant problems while the usage of the KF is not possible. Experimental results show that with perfect and imperfect models, the low rank filters can provide as much accurate estimates as the full KF but at much less computational cost. Localization can help the filter analysis as long as there are enough neighborhood data to the point being analyzed. Estimating the permeabilities of the aquifer is successfully tackled using both the EKF and the SEEKF.

  11. Low-Rank Kalman Filtering in Subsurface Contaminant Transport Models

    KAUST Repository

    El Gharamti, Mohamad

    2010-01-01

    Understanding the geology and the hydrology of the subsurface is important to model the fluid flow and the behavior of the contaminant. It is essential to have an accurate knowledge of the movement of the contaminants in the porous media in order to track them and later extract them from the aquifer. A two-dimensional flow model is studied and then applied on a linear contaminant transport model in the same porous medium. Because of possible different sources of uncertainties, the deterministic model by itself cannot give exact estimations for the future contaminant state. Incorporating observations in the model can guide it to the true state. This is usually done using the Kalman filter (KF) when the system is linear and the extended Kalman filter (EKF) when the system is nonlinear. To overcome the high computational cost required by the KF, we use the singular evolutive Kalman filter (SEKF) and the singular evolutive extended Kalman filter (SEEKF) approximations of the KF operating with low-rank covariance matrices. The SEKF can be implemented on large dimensional contaminant problems while the usage of the KF is not possible. Experimental results show that with perfect and imperfect models, the low rank filters can provide as much accurate estimates as the full KF but at much less computational cost. Localization can help the filter analysis as long as there are enough neighborhood data to the point being analyzed. Estimating the permeabilities of the aquifer is successfully tackled using both the EKF and the SEEKF.

  12. Modelling of contaminant release from a uranium mine tailings site

    International Nuclear Information System (INIS)

    Kahnt, Rene; Metschies, Thomas

    2007-01-01

    Available in abstract form only. Full text of publication follows: Uranium mining and milling continuing from the early 1960's until 1990 close to the town of Seelingstaedt in Eastern Germany resulted in 4 tailings impoundments with a total tailings volume of about 105 Mio. m 3 . Leakage from these tailings impoundments enters the underlying aquifers and is discharged into surface water streams. High concentration of salts, uranium and several heavy metals are released from the tailings. At present the tailings impoundments are reshaped and covered. For the identification of suitable remediation options predictions of the contaminant release for different remediation scenarios have to be made. A compartment model representing the tailings impoundments and the surrounding aquifers for the calculation of contaminant release and transport was set up using the software GOLDSIM. This compartment model describes the time dependent hydraulic conditions within the tailings and the surrounding aquifers taking into account hydraulic and geotechnical processes influencing the hydraulic properties of the tailings material. A simple geochemical approach taking into account sorption processes as well as retardation by applying a k d -approach was implemented to describe the contaminant release and transport within the hydraulic system. For uranium as the relevant contaminant the simple approach takes into account additional geochemical conditions influencing the mobility. Alternatively the model approach allows to include the results of detailed geochemical modelling of the individual tailings zones which is than used as source term for the modelling of the contaminant transport in the aquifer and to the receiving streams. (authors)

  13. Modelling remediation options for urban contamination situations

    DEFF Research Database (Denmark)

    Thiessen, K.M.; Andersson, Kasper Grann; Charnock, T.W.

    2009-01-01

    and remedial options enables the evaluation of a variety of situations or alternative recovery strategies in contexts of preparedness or decision-making. At present a number of models and modelling approaches are available for different purposes. This paper summarizes the available modelling approaches...

  14. Effective dielectric mixture model for characterization of diesel contaminated soil

    International Nuclear Information System (INIS)

    Al-Mattarneh, H.M.A.

    2007-01-01

    Human exposure to contaminated soil by diesel isomers can have serious health consequences like neurological diseases or cancer. The potential of dielectric measuring techniques for electromagnetic characterization of contaminated soils was investigated in this paper. The purpose of the research was to develop an empirical dielectric mixture model for soil hydrocarbon contamination application. The paper described the basic theory and elaborated in dielectric mixture theory. The analytical and empirical models were explained in simple algebraic formulas. The experimental study was then described with reference to materials, properties and experimental results. The results of the analytical models were also mathematically explained. The proposed semi-empirical model was also presented. According to the result of the electromagnetic properties of dry soil contaminated with diesel, the diesel presence had no significant effect on the electromagnetic properties of dry soil. It was concluded that diesel had no contribution to the soil electrical conductivity, which confirmed the nonconductive character of diesel. The results of diesel-contaminated soil at saturation condition indicated that both dielectric constant and loss factors of soil were decreased with increasing diesel content. 15 refs., 2 tabs., 9 figs

  15. Fuzzy One-Class Classification Model Using Contamination Neighborhoods

    Directory of Open Access Journals (Sweden)

    Lev V. Utkin

    2012-01-01

    Full Text Available A fuzzy classification model is studied in the paper. It is based on the contaminated (robust model which produces fuzzy expected risk measures characterizing classification errors. Optimal classification parameters of the models are derived by minimizing the fuzzy expected risk. It is shown that an algorithm for computing the classification parameters is reduced to a set of standard support vector machine tasks with weighted data points. Experimental results with synthetic data illustrate the proposed fuzzy model.

  16. Sediment and toxic contaminant transport modeling in coastal waters

    International Nuclear Information System (INIS)

    Onishi, Yasuo; Mayer, D.W.; Argo, R.S.

    1982-01-01

    Models are presented to estimate the migration of toxic contaminants in coastal waters. Ocean current is simulated by the vertically-averaged, finite element, two-demensional model known as CAFE-I with the Galerkin weighted residual technique. The refraction of locally generated waves or swells is simulated by the wave refraction model, LO3D. Using computed current, depth, and wave characteristics, the finite element model, FETRA, simulated sediment and contaminant transport in coastal waters, estuaries and rivers. Prior to the application of these models to the Irish Sea and other coastal waters, the finite element model, FETRA, was tested to demonstrate its ability to simulate sediment and contaminant interaction, and the mechanism governing the transport, deposition, and resuspension of contaminated sediment. Several simple equations such as the unsteady, advection-diffusion equation, the equation for noncohesive-sediment load due to wind-induced waves in offshore and surf zones, and the equation for sediment-radionuclide transport simulation were solved during the preliminary testing of the model. (Kato, T.)

  17. Modelling contaminant transport in saturated aquifers

    International Nuclear Information System (INIS)

    Lakshminarayana, V.; Nayak, T.R.

    1990-01-01

    With the increase in population and industrialization the problem of pollution of groundwater has become critical. The present study deals with modelling of pollutant transport through saturated aquifers. Using this model it is possible to predict the concentration distribution, spatial as well as temporal, in the aquifer. The paper also deals with one of the methods of controlling the pollutant movement, namely by pumping wells. A simulation model is developed to determine the number, location and rate of pumping of a number of wells near the source of pollution so that the concentration is within acceptable limits at the point of interest. (Author) (18 refs., 14 figs., tab.)

  18. A model for dispersion of contaminants in the subway environment

    Energy Technology Data Exchange (ETDEWEB)

    Coke, L. R.; Sanchez, J. G.; Policastro, A. J.

    2000-05-03

    Although subway ventilation has been studied extensively, very little has been published on dispersion of contaminants in the subway environment. This paper presents a model that predicts dispersion of contaminants in a complex subway system. It accounts for the combined transient effects of train motion, station airflows, train car air exchange rates, and source release properties. Results are presented for a range of typical subway scenarios. The effects of train piston action and train car air exchange are discussed. The model could also be applied to analyze the environmental impact of hazardous materials releases such as chemical and biological agents.

  19. Modeling Groundwater-Surface Water Interaction and Contaminant Transport of Chlorinated Solvent Contaminated Site

    Science.gov (United States)

    Yimer Ebrahim, Girma; Jonoski, Andreja; van Griensven, Ann; Dujardin, Juliette; Baetelaan, Okke; Bronders, Jan

    2010-05-01

    Chlorinated-solvent form one of the largest groups of environmental chemicals. Their use and misuse in industry have lead to a large entry of these chemicals into the environment, resulting in widespread dissemination and oftentimes environmental contamination. Chlorinated solvent contamination of groundwater resources has been widely reported. For instance, there has been much interest in the assessment of these contaminant levels and their evolutions with time in the groundwater body below the Vilvoorde-Machelen industrial area (Belgium). The long industrial history of the area has lead to complex patterns of pollution from multiple sources and the site has been polluted to the extent that individual plumes are not definable any more. Understanding of groundwater/surface water interaction is a critical component for determining the fate of contaminant both in streams and ground water due to the fact that groundwater and surface water are in continuous dynamic interaction in the hydrologic cycle. The interaction has practical consequences in the quantity and quality of water in either system in the sense that depletion and/or contamination of one of the system will eventually affect the other one. The transition zone between a stream and its adjacent aquifer referred to as the hyporheic zone plays a critical role in governing contaminant exchange and transformation during water exchange between the two water bodies. The hyporheic zone of Zenne River ( the main receptor ) is further complicated due to the fact that the river banks are artificially trained with sheet piles along its reach extending some 12 m below the surface. This study demonstrates the use of MODFLOW, a widely used modular three-dimensional block-centred finite difference, saturated flow model for simulating the flow and direction of movement of groundwater through aquifer and stream-aquifer interaction and the use of transport model RT3D, a three-dimensional multi-species reactive transport model

  20. Radiative transfer model for contaminated rough slabs.

    Science.gov (United States)

    Andrieu, François; Douté, Sylvain; Schmidt, Frédéric; Schmitt, Bernard

    2015-11-01

    We present a semi-analytical model to simulate the bidirectional reflectance distribution function (BRDF) of a rough slab layer containing impurities. This model has been optimized for fast computation in order to analyze massive hyperspectral data by a Bayesian approach. We designed it for planetary surface ice studies but it could be used for other purposes. It estimates the bidirectional reflectance of a rough slab of material containing inclusions, overlaying an optically thick media (semi-infinite media or stratified media, for instance granular material). The inclusions are assumed to be close to spherical and constituted of any type of material other than the ice matrix. It can be any other type of ice, mineral, or even bubbles defined by their optical constants. We assume a low roughness and we consider the geometrical optics conditions. This model is thus applicable for inclusions larger than the considered wavelength. The scattering on the inclusions is assumed to be isotropic. This model has a fast computation implementation and thus is suitable for high-resolution hyperspectral data analysis.

  1. A Coupled model for ERT monitoring of contaminated sites

    Science.gov (United States)

    Wang, Yuling; Zhang, Bo; Gong, Shulan; Xu, Ya

    2018-02-01

    The performance of electrical resistivity tomography (ERT) system is usually investigated using a fixed resistivity distribution model in numerical simulation study. In this paper, a method to construct a time-varying resistivity model by coupling water transport, solute transport and constant current field is proposed for ERT monitoring of contaminated sites. Using the proposed method, a monitoring model is constructed for a contaminated site with a pollution region on the surface and ERT monitoring results at different time is calculated by the finite element method. The results show that ERT monitoring profiles can effectively reflect the increase of the pollution area caused by the diffusion of pollutants, but the extent of the pollution is not exactly the same as the actual situation. The model can be extended to any other case and can be used to scheme design and results analysis for ERT monitoring.

  2. General dosimetry model for internal contamination with radioisotopes

    International Nuclear Information System (INIS)

    Nino, L.

    1989-01-01

    Radiation dose by inner contamination with radioisotopes is not measured directly but evaluated by the application of mathematical models of fixation and elimination, taken into account biological activity of each organ with respect to the incorporated material. Models proposed by ICRP for the respiratory and gastrointestinal tracts (30) seems that they should not be applied independently because of the evident correlation between them. In this paper both models are integrated in a more general one with neither modification nor limitation of the starting models. It has been applied to some patients in the Instituto Nacional de Cancerologia, who received some I-131 dose via oral and results are quite similar to dose experimentally obtained via urine spectrograms. Based on this results the method was formalized and applied to professional exposed personnel of the medical staff at the same Institute; due to high doses found in some of the urine samples, probable I-131 air contamination could be supposed

  3. CSOIL 2000 an exposure model for human risk assessment of soil contamination. A model description

    NARCIS (Netherlands)

    Brand E; Otte PF; Lijzen JPA; LER

    2007-01-01

    This RIVM description of the CSOIL 2000 model deals, for the first time, with all aspects of the model. CSOIL 2000 can be used to derive intervention values. Intervention values are calculated for contaminated soil and represent a measure for determining when contaminated soil needs to be

  4. Modelling the fate of oxidisable organic contaminants in groundwater

    DEFF Research Database (Denmark)

    Barry, D.A.; Prommer, H.; Miller, C.T.

    2002-01-01

    modelling framework is illustrated by pertinent examples, showing the degradation of dissolved organics by microbial activity limited by the availability of nutrients or electron acceptors (i.e., changing redox states), as well as concomitant secondary reactions. Two field-scale modelling examples......Subsurface contamination by organic chemicals is a pervasive environmental problem, susceptible to remediation by natural or enhanced attenuation approaches or more highly engineered methods such as pump-and-treat, amongst others. Such remediation approaches, along with risk assessment...... are discussed, the Vejen landfill (Denmark) and an example where metal contamination is remediated by redox changes wrought by injection of a dissolved organic compound. A summary is provided of current and likely future challenges to modelling of oxidisable organics in the subsurface. (C) 2002 Elsevier Science...

  5. Limitations of sorption isotherms on modeling groundwater contaminant transport

    International Nuclear Information System (INIS)

    Silva, Eduardo Figueira da

    2007-01-01

    Design and safety assessment of radioactive waste repositories, as well as remediation of radionuclide contaminated groundwater require the development of models capable of accurately predicting trace element fate and transport. Adsorption of trace radionuclides onto soils and groundwater is an important mechanism controlling near- and far- field transport. Although surface complexation models (SCMs) can better describe the adsorption mechanisms of most radionuclides onto mineral surfaces by directly accounting for variability of system properties and mineral surface properties, isotherms are still used to model contaminant transport in groundwater, despite the much higher system dependence. The present work investigates differences between transport model results based on these two approaches for adsorption modeling. A finite element transport model is used for the isotherm model, whereas the computer program PHREEQC is used for the SCM approach. Both models are calibrated for a batch experiment, and one-dimensional transport is simulated using the calibrated parameters. At the lower injected concentrations there are large discrepancies between SCM and isotherm transport predictions, with the SCM presenting much longer tails on the breakthrough curves. Isotherms may also provide non-conservative results for time to breakthrough and for maximum concentration in a contamination plume. Isotherm models are shown not to be robust enough to predict transport behavior of some trace elements, thus discouraging their use. The results also illustrate the promise of the SCM modeling approach in safety assessment and environmental remediation applications, also suggesting that independent batch sorption measurements can be used, within the framework of the SCM, to produce a more versatile and realistic groundwater transport model for radionuclides which is capable of accounting more accurately for temporal and spatial variations in geochemical conditions. (author)

  6. Simplified model for radioactive contaminant transport: the TRANSS code

    International Nuclear Information System (INIS)

    Simmons, C.S.; Kincaid, C.T.; Reisenauer, A.E.

    1986-09-01

    A simplified ground-water transport model called TRANSS was devised to estimate the rate of migration of a decaying radionuclide that is subject to sorption governed by a linear isotherm. Transport is modeled as a contaminant mass transmitted along a collection of streamlines constituting a streamtube, which connects a source release zone with an environmental arrival zone. The probability-weighted contaminant arrival distribution along each streamline is represented by an analytical solution of the one-dimensional advection-dispersion equation with constant velocity and dispersion coefficient. The appropriate effective constant velocity for each streamline is based on the exact travel time required to traverse a streamline with a known length. An assumption used in the model to facilitate the mathematical simplification is that transverse dispersion within a streamtube is negligible. Release of contaminant from a source is described in terms of a fraction-remaining curve provided as input information. However, an option included in the code is the calculation of a fraction-remaining curve based on four specialized release models: (1) constant release rate, (2) solubility-controlled release, (3) adsorption-controlled release, and (4) diffusion-controlled release from beneath an infiltration barrier. To apply the code, a user supplies only a certain minimal number of parameters: a probability-weighted list of travel times for streamlines, a local-scale dispersion coefficient, a sorption distribution coefficient, total initial radionuclide inventory, radioactive half-life, a release model choice, and size dimensions of the source. The code is intended to provide scoping estimates of contaminant transport and does not predict the evolution of a concentration distribution in a ground-water flow field. Moreover, the required travel times along streamlines must be obtained from a prior ground-water flow simulation

  7. A generic model of contaminant migration from uranium tailings impoundments

    International Nuclear Information System (INIS)

    Shepherd, T.A.; Brown, S.E.

    1982-01-01

    This paper presents an analytical hydrogeochemical model based upon acid consumption-neutralization front movement. The development of contaminant plumes is discussed and distinct zones within these plumes are identified and characterized. The most important process influencing the rate and extent of contaminant migration at acid-leach uranium tailings impoundments is the neutralization of seepage water by soils along ground water flow paths. The chemical characteristics of the ground water is determined in order to identify and characterize zones within migrating plumes of tailings-derived water. It is concluded that the characterization of specific zones is useful in the interpretation of existing conditions, in the evaluation of future migration, and in the determination of appropriate models for the specific situation

  8. Discriminative Random Field Models for Subsurface Contamination Uncertainty Quantification

    Science.gov (United States)

    Arshadi, M.; Abriola, L. M.; Miller, E. L.; De Paolis Kaluza, C.

    2017-12-01

    Application of flow and transport simulators for prediction of the release, entrapment, and persistence of dense non-aqueous phase liquids (DNAPLs) and associated contaminant plumes is a computationally intensive process that requires specification of a large number of material properties and hydrologic/chemical parameters. Given its computational burden, this direct simulation approach is particularly ill-suited for quantifying both the expected performance and uncertainty associated with candidate remediation strategies under real field conditions. Prediction uncertainties primarily arise from limited information about contaminant mass distributions, as well as the spatial distribution of subsurface hydrologic properties. Application of direct simulation to quantify uncertainty would, thus, typically require simulating multiphase flow and transport for a large number of permeability and release scenarios to collect statistics associated with remedial effectiveness, a computationally prohibitive process. The primary objective of this work is to develop and demonstrate a methodology that employs measured field data to produce equi-probable stochastic representations of a subsurface source zone that capture the spatial distribution and uncertainty associated with key features that control remediation performance (i.e., permeability and contamination mass). Here we employ probabilistic models known as discriminative random fields (DRFs) to synthesize stochastic realizations of initial mass distributions consistent with known, and typically limited, site characterization data. Using a limited number of full scale simulations as training data, a statistical model is developed for predicting the distribution of contaminant mass (e.g., DNAPL saturation and aqueous concentration) across a heterogeneous domain. Monte-Carlo sampling methods are then employed, in conjunction with the trained statistical model, to generate realizations conditioned on measured borehole data

  9. Benchmarking of a Markov multizone model of contaminant transport.

    Science.gov (United States)

    Jones, Rachael M; Nicas, Mark

    2014-10-01

    A Markov chain model previously applied to the simulation of advection and diffusion process of gaseous contaminants is extended to three-dimensional transport of particulates in indoor environments. The model framework and assumptions are described. The performance of the Markov model is benchmarked against simple conventional models of contaminant transport. The Markov model is able to replicate elutriation predictions of particle deposition with distance from a point source, and the stirred settling of respirable particles. Comparisons with turbulent eddy diffusion models indicate that the Markov model exhibits numerical diffusion in the first seconds after release, but over time accurately predicts mean lateral dispersion. The Markov model exhibits some instability with grid length aspect when turbulence is incorporated by way of the turbulent diffusion coefficient, and advection is present. However, the magnitude of prediction error may be tolerable for some applications and can be avoided by incorporating turbulence by way of fluctuating velocity (e.g. turbulence intensity). © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  10. Kinetic model for the dosimetry of radiopharmaceuticals contaminated by Mo-99

    International Nuclear Information System (INIS)

    Shearer, D.R.; Pezzullo, J.C.

    1986-01-01

    Radiopharmaceuticals tagged with Tc-99m may become contaminated with breakthrough products from the Mo-99/Tc-99m generator. If a fraction of the contaminant becomes bound to the radiopharmaceutical, the dose to the radiopharmaceutical target organ from the contaminant must be considered. The dose to the contaminant target organ may then be calculated as the sum of the doses from a) the initially unbound contaminant, and b) the contaminant later released by degradation of the radiopharmaceutical. This paper presents a model which takes the above processes into account. The model is illustrated with clinical data derived from Mo-99 contaminated radiopharmaceuticals. 5 references, 2 figures, 6 tables

  11. Low-rank Kalman filtering for efficient state estimation of subsurface advective contaminant transport models

    KAUST Repository

    El Gharamti, Mohamad; Hoteit, Ibrahim; Sun, Shuyu

    2012-01-01

    Accurate knowledge of the movement of contaminants in porous media is essential to track their trajectory and later extract them from the aquifer. A two-dimensional flow model is implemented and then applied on a linear contaminant transport model

  12. A deterministic-probabilistic model for contaminant transport. User manual

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, F W; Crowe, A

    1980-08-01

    This manual describes a deterministic-probabilistic contaminant transport (DPCT) computer model designed to simulate mass transfer by ground-water movement in a vertical section of the earth's crust. The model can account for convection, dispersion, radioactive decay, and cation exchange for a single component. A velocity is calculated from the convective transport of the ground water for each reference particle in the modeled region; dispersion is accounted for in the particle motion by adding a readorn component to the deterministic motion. The model is sufficiently general to enable the user to specify virtually any type of water table or geologic configuration, and a variety of boundary conditions. A major emphasis in the model development has been placed on making the model simple to use, and information provided in the User Manual will permit changes to the computer code to be made relatively easily for those that might be required for specific applications. (author)

  13. Modelling contaminant transport using site specific data from Vaalputs

    International Nuclear Information System (INIS)

    Botha, J.F.

    1986-01-01

    The transport of a contaminant through the upper layers of the earth's surface is a complex phenomenon. To develop a model for this, requires a good understanding of the physical nature of the phenomenon. This paper discusses two difficulties frequently encountered in developing such a model - the nature of the subsurface and the mathematical representation of the unsaturated hydraulic parameters. It is proposed that information obtained from pump- and packer tests be used to circumvent the first difficulty, and that the unsaturated flow parameters be approximated by C -∞ continuous function

  14. Contaminant plume configuration and movement: an experimental model

    Science.gov (United States)

    Alencoao, A.; Reis, A.; Pereira, M. G.; Liberato, M. L. R.; Caramelo, L.; Amraoui, M.; Amorim, V.

    2009-04-01

    The relevance of Science and Technology in our daily routines makes it compulsory to educate citizens who have both scientific literacy and scientific knowledge. These will allow them to be intervening citizens in a constantly changing society. Thus, physical and natural sciences are included in school curricula, both in primary and secondary education, with the fundamental aim of developing in the students the skills, attitudes and knowledge needed for the understanding of the planet Earth and its real problems. On the other hand, teaching in Geosciences is more and more based on practical methodologies which use didactic material, sustaining teachers' pedagogical practices and facilitating students' learning tasks suggested on the syllabus defined for each school level. Themes related to exploring the different components of the Hydrological Cycle and themes related to natural environment protection and preservation, namely water resources and soil contamination by industrial and urban sewage are examples of subject matters included on the Portuguese syllabus. These topics motivated the conception and construction of experimental models for the study of the propagation of pollutants on a porous medium. The experimental models allow inducing a horizontal flux of water though different kinds of permeable substances (e.g. sand, silt), with contamination spots on its surface. These experimental activities facilitate the student to understand the flow path of contaminating substances on the saturated zone and to observe the contaminant plume configuration and movement. The activities are explored in a teaching and learning process perspective where the student builds its own knowledge through real question- problem based learning which relate Science, Technology and Society. These activities have been developed in the framework of project ‘Water in the Environment' (CV/PVI/0854) of the POCTI Program (Programa Operacional "Ciência, Tecnologia, Inovação") financed

  15. Experimental and modelling studies of radionuclide migration from contaminated groundwaters

    International Nuclear Information System (INIS)

    Tompkins, J. A.; Butler, A. P.; Wheater, H. S.; Shaw, G.; Wadey, P.; Bell, J. N. B.

    1994-01-01

    Lysimeter-based studies of radionuclide uptake by winter wheat are being undertaken to investigate soil-to-plant transfer processes. A five year multi-disciplinary research project has concentrated on the upward migration of contaminants from near surface water-tables and their subsequent uptake by a winter wheat crop. A weighted transfer factor approach and a physically based modelling methodology, for the simulation and prediction of radionuclide uptake, have been developed which offer alternatives to the traditional transfer factor approach. Integrated hydrological and solute transport models are used to simulate contaminant movement and subsequent root uptake. This approach enables prediction of radionuclide transport for a wide range of soil, plant and radionuclide types. This paper presents simulated results of 22 Na plant uptake and soil activity profiles, which are verified with respect to lysimeter data. The results demonstrate that a simple modelling approach can describe the variability in radioactivity in both the harvested crop and the soil profile, without recourse to a large number of empirical parameters. The proposed modelling technique should be readily applicable to a range of scales and conditions, since it embodies an understanding of the underlying physical processes of the system. This work constitutes part of an ongoing research programme being undertaken by UK Nirex Ltd., to assess the long term safety of a deep level repository for low and intermediate level nuclear waste. (author)

  16. Contaminant transport model validation: The Oak Ridge Reservation

    International Nuclear Information System (INIS)

    Lee, R.R.; Ketelle, R.H.

    1988-09-01

    In the complex geologic setting on the Oak Ridge Reservation, hydraulic conductivity is anisotropic and flow is strongly influenced by an extensive and largely discontinuous fracture network. Difficulties in describing and modeling the aquifer system prompted a study to obtain aquifer property data to be used in a groundwater flow model validation experiment. Characterization studies included the performance of an extensive suite of aquifer test within a 600-square-meter area to obtain aquifer property values to describe the flow field in detail. Following aquifer test, a groundwater tracer test was performed under ambient conditions to verify the aquifer analysis. Tracer migration data in the near-field were used in model calibration to predict tracer arrival time and concentration in the far-field. Despite the extensive aquifer testing, initial modeling inaccurately predicted tracer migration direction. Initial tracer migration rates were consistent with those predicted by the model; however, changing environmental conditions resulted in an unanticipated decay in tracer movement. Evaluation of the predictive accuracy of groundwater flow and contaminant transport models on the Oak Ridge Reservation depends on defining the resolution required, followed by field testing and model grid definition at compatible scales. The use of tracer tests, both as a characterization method and to verify model results, provides the highest level of resolution of groundwater flow characteristics. 3 refs., 4 figs

  17. Methodology for modeling the microbial contamination of air filters.

    Science.gov (United States)

    Joe, Yun Haeng; Yoon, Ki Young; Hwang, Jungho

    2014-01-01

    In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

  18. Methodology for modeling the microbial contamination of air filters.

    Directory of Open Access Journals (Sweden)

    Yun Haeng Joe

    Full Text Available In this paper, we propose a theoretical model to simulate microbial growth on contaminated air filters and entrainment of bioaerosols from the filters to an indoor environment. Air filter filtration and antimicrobial efficiencies, and effects of dust particles on these efficiencies, were evaluated. The number of bioaerosols downstream of the filter could be characterized according to three phases: initial, transitional, and stationary. In the initial phase, the number was determined by filtration efficiency, the concentration of dust particles entering the filter, and the flow rate. During the transitional phase, the number of bioaerosols gradually increased up to the stationary phase, at which point no further increase was observed. The antimicrobial efficiency and flow rate were the dominant parameters affecting the number of bioaerosols downstream of the filter in the transitional and stationary phase, respectively. It was found that the nutrient fraction of dust particles entering the filter caused a significant change in the number of bioaerosols in both the transitional and stationary phases. The proposed model would be a solution for predicting the air filter life cycle in terms of microbiological activity by simulating the microbial contamination of the filter.

  19. Modeling uranium transport in acidic contaminated groundwater with base addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fan [Institute of Tibetan Plateau Research, Chinese Academy of Sciences; Luo, Wensui [ORNL; Parker, Jack C. [University of Tennessee, Knoxville (UTK); Brooks, Scott C [ORNL; Watson, David B [ORNL; Jardine, Philip [University of Tennessee, Knoxville (UTK); Gu, Baohua [ORNL

    2011-01-01

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  20. Modeling uranium transport in acidic contaminated groundwater with base addition

    International Nuclear Information System (INIS)

    Zhang Fan; Luo Wensui; Parker, Jack C.; Brooks, Scott C.; Watson, David B.; Jardine, Philip M.; Gu Baohua

    2011-01-01

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO 3 - , SO 4 2- , U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  1. Modeling uranium transport in acidic contaminated groundwater with base addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Fan, E-mail: zhangfan@itpcas.ac.cn [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085 (China); Luo Wensui [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 (China); Parker, Jack C. [Institute for a Secure and Sustainable Environment, Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Brooks, Scott C.; Watson, David B. [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Jardine, Philip M. [Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN 37996 (United States); Gu Baohua [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2011-06-15

    This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.

  2. X-231B technology demonstration for in situ treatment of contaminated soil: Contaminant characterization and three dimensional spatial modeling

    International Nuclear Information System (INIS)

    West, O.R.; Siegrist, R.L.; Mitchell, T.J.; Pickering, D.A.; Muhr, C.A.; Greene, D.W.; Jenkins, R.A.

    1993-11-01

    Fine-textured soils and sediments contaminated by trichloroethylene (TCE) and other chlorinated organics present a serious environmental restoration challenge at US Department of Energy (DOE) sites. DOE and Martin Marietta Energy Systems, Inc. initiated a research and demonstration project at Oak Ridge National Laboratory. The goal of the project was to demonstrate a process for closure and environmental restoration of the X-231B Solid Waste Management Unit at the DOE Portsmouth Gaseous Diffusion Plant. The X-231B Unit was used from 1976 to 1983 as a land disposal site for waste oils and solvents. Silt and clay deposits beneath the unit were contaminated with volatile organic compounds and low levels of radioactive substances. The shallow groundwater was also contaminated, and some contaminants were at levels well above drinking water standards. This document begins with a summary of the subsurface physical and contaminant characteristics obtained from investigative studies conducted at the X-231B Unit prior to January 1992 (Sect. 2). This is then followed by a description of the sample collection and analysis methods used during the baseline sampling conducted in January 1992 (Sect. 3). The results of this sampling event were used to develop spatial models for VOC contaminant distribution within the X-231B Unit

  3. Requirements for modeling airborne microbial contamination in space stations

    Science.gov (United States)

    Van Houdt, Rob; Kokkonen, Eero; Lehtimäki, Matti; Pasanen, Pertti; Leys, Natalie; Kulmala, Ilpo

    2018-03-01

    Exposure to bioaerosols is one of the facets that affect indoor air quality, especially for people living in densely populated or confined habitats, and is associated to a wide range of health effects. Good indoor air quality is thus vital and a prerequisite for fully confined environments such as space habitats. Bioaerosols and microbial contamination in these confined space stations can have significant health impacts, considering the unique prevailing conditions and constraints of such habitats. Therefore, biocontamination in space stations is strictly monitored and controlled to ensure crew and mission safety. However, efficient bioaerosol control measures rely on solid understanding and knowledge on how these bioaerosols are created and dispersed, and which factors affect the survivability of the associated microorganisms. Here we review the current knowledge gained from relevant studies in this wide and multidisciplinary area of bioaerosol dispersion modeling and biological indoor air quality control, specifically taking into account the specific space conditions.

  4. Mathematical modeling of groundwater contamination with varying velocity field

    Directory of Open Access Journals (Sweden)

    Das Pintu

    2017-06-01

    Full Text Available In this study, analytical models for predicting groundwater contamination in isotropic and homogeneous porous formations are derived. The impact of dispersion and diffusion coefficients is included in the solution of the advection-dispersion equation (ADE, subjected to transient (time-dependent boundary conditions at the origin. A retardation factor and zero-order production terms are included in the ADE. Analytical solutions are obtained using the Laplace Integral Transform Technique (LITT and the concept of linear isotherm. For illustration, analytical solutions for linearly space- and time-dependent hydrodynamic dispersion coefficients along with molecular diffusion coefficients are presented. Analytical solutions are explored for the Peclet number. Numerical solutions are obtained by explicit finite difference methods and are compared with analytical solutions. Numerical results are analysed for different types of geological porous formations i.e., aquifer and aquitard. The accuracy of results is evaluated by the root mean square error (RMSE.

  5. Modeling Organic Contaminant Desorption from Municipal Solid Waste Components

    Science.gov (United States)

    Knappe, D. R.; Wu, B.; Barlaz, M. A.

    2002-12-01

    Approximately 25% of the sites on the National Priority List (NPL) of Superfund are municipal landfills that accepted hazardous waste. Unlined landfills typically result in groundwater contamination, and priority pollutants such as alkylbenzenes are often present. To select cost-effective risk management alternatives, better information on factors controlling the fate of hydrophobic organic contaminants (HOCs) in landfills is required. The objectives of this study were (1) to investigate the effects of HOC aging time, anaerobic sorbent decomposition, and leachate composition on HOC desorption rates, and (2) to simulate HOC desorption rates from polymers and biopolymer composites with suitable diffusion models. Experiments were conducted with individual components of municipal solid waste (MSW) including polyvinyl chloride (PVC), high-density polyethylene (HDPE), newsprint, office paper, and model food and yard waste (rabbit food). Each of the biopolymer composites (office paper, newsprint, rabbit food) was tested in both fresh and anaerobically decomposed form. To determine the effects of aging on alkylbenzene desorption rates, batch desorption tests were performed after sorbents were exposed to toluene for 30 and 250 days in flame-sealed ampules. Desorption tests showed that alkylbenzene desorption rates varied greatly among MSW components (PVC slowest, fresh rabbit food and newsprint fastest). Furthermore, desorption rates decreased as aging time increased. A single-parameter polymer diffusion model successfully described PVC and HDPE desorption data, but it failed to simulate desorption rate data for biopolymer composites. For biopolymer composites, a three-parameter biphasic polymer diffusion model was employed, which successfully simulated both the initial rapid and the subsequent slow desorption of toluene. Toluene desorption rates from MSW mixtures were predicted for typical MSW compositions in the years 1960 and 1997. For the older MSW mixture, which had a

  6. Modelling assessment of regional groundwater contamination due to historic smelter emissions of heavy metals

    NARCIS (Netherlands)

    Grift, B. van der; Griffioen, J.

    2008-01-01

    Historic emissions from ore smelters typically cause regional soil contamination. We developed a modelling approach to assess the impact of such contamination on groundwater and surface water load, coupling unsaturated zone leaching modelling with 3D groundwater transport modelling. Both historic

  7. Modeling Catalytic Destruction of Subsurface Contaminants in Recirculating Wells

    National Research Council Canada - National Science Library

    Cadena, Kerry

    2003-01-01

    ... (National Research Council, 1994). Examples of groundwater contaminants of special interest to DoD and AF installations include fuel hydrocarbons, chlorinated hydrocarbons, and nitroaromatic compounds...

  8. Can Bayesian Belief Networks help tackling conceptual model uncertainties in contaminated site risk assessment?

    DEFF Research Database (Denmark)

    Troldborg, Mads; Thomsen, Nanna Isbak; McKnight, Ursula S.

    different conceptual models may describe the same contaminated site equally well. In many cases, conceptual model uncertainty has been shown to be one of the dominant sources for uncertainty and is therefore essential to account for when quantifying uncertainties in risk assessments. We present here......A key component in risk assessment of contaminated sites is the formulation of a conceptual site model. The conceptual model is a simplified representation of reality and forms the basis for the mathematical modelling of contaminant fate and transport at the site. A conceptual model should...... a Bayesian Belief Network (BBN) approach for evaluating the uncertainty in risk assessment of groundwater contamination from contaminated sites. The approach accounts for conceptual model uncertainty by considering multiple conceptual models, each of which represents an alternative interpretation of the site...

  9. Modeling the migration of radioactive contaminants in groundwater of in situ leaching uranium mine

    International Nuclear Information System (INIS)

    Li Chunguang; Tai Kaixuan

    2011-01-01

    The radioactive contamination of groundwater from in situ leaching (ISL) of uranium mining is a widespread environmental problem. This paper analyzed the monitor results of groundwater contaminations for a in situ leaching uranium mine. A dynamic model of contaminants transport in groundwater in ISL well field was established. The processes and mechanisms of contaminant transport in groundwater were simulated numerically for a ISL well field. A small quantity of U and SO 4 2- migrate to outside of well field during ISL production stage. But the migration velocity and distance of contaminations is small, and the concentration is low. Contaminants migrate as anomalistic tooth-shape. The migration trend of U and SO 4 2- is consistent. Numerical modeling can provide an effective approach to analyse the transport mechanism, and forecast and control the migration of contaminants in groundwater in ISL well field. (authors)

  10. Contaminant transport in aquifers: improving the determination of model parameters

    International Nuclear Information System (INIS)

    Sabino, C.V.S.; Moreira, R.M.; Lula, Z.L.; Chausson, Y.; Magalhaes, W.F.; Vianna, M.N.

    1998-01-01

    Parameters conditioning the migration behavior of cesium and mercury are measured with their tracers 137 Cs and 203 Hg in the laboratory, using both batch and column experiments. Batch tests were used to define the sorption isotherm characteristics. Also investigated were the influences of some test parameters, in particular those due to the volume of water to mass of soil ratio (V/m). A provisional relationship between V/m and the distribution coefficient, K d , has been advanced, and a procedure to estimate K d 's valid for environmental values of the ratio V/m has been suggested. Column tests provided the parameters for a transport model. A major problem to be dealt with in such tests is the collimation of the radioactivity probe. Besides mechanically optimizing the collimator, a deconvolution procedure has been suggested and tested, with statistical criteria, to filter off both noise and spurious tracer signals. Correction procedures for the integrating effect introduced by sampling at the exit of columns have also been developed. These techniques may be helpful in increasing the accuracy required in the measurement of parameters conditioning contaminant migration in soils, thus allowing more reliable predictions based on mathematical model applications. (author)

  11. Evaluation of Contamination Inspection and Analysis Methods through Modeling System Performance

    Science.gov (United States)

    Seasly, Elaine; Dever, Jason; Stuban, Steven M. F.

    2016-01-01

    Contamination is usually identified as a risk on the risk register for sensitive space systems hardware. Despite detailed, time-consuming, and costly contamination control efforts during assembly, integration, and test of space systems, contaminants are still found during visual inspections of hardware. Improved methods are needed to gather information during systems integration to catch potential contamination issues earlier and manage contamination risks better. This research explores evaluation of contamination inspection and analysis methods to determine optical system sensitivity to minimum detectable molecular contamination levels based on IEST-STD-CC1246E non-volatile residue (NVR) cleanliness levels. Potential future degradation of the system is modeled given chosen modules representative of optical elements in an optical system, minimum detectable molecular contamination levels for a chosen inspection and analysis method, and determining the effect of contamination on the system. By modeling system performance based on when molecular contamination is detected during systems integration and at what cleanliness level, the decision maker can perform trades amongst different inspection and analysis methods and determine if a planned method is adequate to meet system requirements and manage contamination risk.

  12. Comparison of different modeling approaches to simulate contaminant transport in a fractured limestone aquifer

    DEFF Research Database (Denmark)

    Mosthaf, Klaus; Rosenberg, L.; Balbarini, Nicola

    . Given available field data and model purpose, this paper therefore aims to develop, examine and compare modeling approaches for transport of contaminants in fractured limestone aquifers. The model comparison was conducted for a contaminated site in Denmark, where a plume of a dissolved contaminant (PCE...... was combined with an analysis of heterogeneities and fractures from a nearby excavation (analog site). Methods for translating the geological information and fracture mapping into each of the model concepts were examined. Each model was compared with available field data, considering both model fit...... of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias towards fracture sampling, however concentrations in the limestone matrix are needed for assessing contaminant...

  13. Modeling In Situ Bioremediation of Perchlorate-Contaminated Groundwater

    National Research Council Canada - National Science Library

    Secody, Roland E

    2007-01-01

    .... An innovative technology was recently developed which uses dual-screened treatment wells to mix an electron donor into perchlorate-contaminated groundwater in order to effect in situ bioremediation...

  14. Modeled Watershed Runoff Associated with Variations in Precipitation Data with Implications for Contaminant Fluxes

    Science.gov (United States)

    Watershed-scale fate and transport models are important tools for estimating the sources, transformation, and transport of contaminants to surface water systems. Precipitation is one of the primary inputs to watershed biogeochemical models, influencing changes in the water budge...

  15. Finite element analysis of a model scale footing on clean and oil contaminated sand

    International Nuclear Information System (INIS)

    Evgin, E.; Boulon, M.; Das, B.M.

    1995-01-01

    The effects of oil contamination on the behavior of a model scale footing is determined. Tests are carried out with both clean and oil contaminated sand. The data show that the bearing capacity of the footing is reduced significantly as a result of oil contamination. A finite element analysis is performed to calculate the bearing capacity of the footing and the results are compared with the experimental data. The significance of using an interface element in the analysis is discussed

  16. Evaluation of Different Modeling Approaches to Simulate Contaminant Transport in a Fractured Limestone Aquifer

    Science.gov (United States)

    Mosthaf, K.; Rosenberg, L.; Balbarini, N.; Broholm, M. M.; Bjerg, P. L.; Binning, P. J.

    2014-12-01

    It is important to understand the fate and transport of contaminants in limestone aquifers because they are a major drinking water resource. This is challenging because they are highly heterogeneous; with micro-porous grains, flint inclusions, and being heavily fractured. Several modeling approaches have been developed to describe contaminant transport in fractured media, such as the discrete fracture (with various fracture geometries), equivalent porous media (with and without anisotropy), and dual porosity models. However, these modeling concepts are not well tested for limestone geologies. Given available field data and model purpose, this paper therefore aims to develop, examine and compare modeling approaches for transport of contaminants in fractured limestone aquifers. The model comparison was conducted for a contaminated site in Denmark, where a plume of a dissolved contaminant (PCE) has migrated through a fractured limestone aquifer. Multilevel monitoring wells have been installed at the site and available data includes information on spill history, extent of contamination, geology and hydrogeology. To describe the geology and fracture network, data from borehole logs was combined with an analysis of heterogeneities and fractures from a nearby excavation (analog site). Methods for translating the geological information and fracture mapping into each of the model concepts were examined. Each model was compared with available field data, considering both model fit and measures of model suitability. An analysis of model parameter identifiability and sensitivity is presented. Results show that there is considerable difference between modeling approaches, and that it is important to identify the right one for the actual scale and model purpose. A challenge in the use of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias

  17. Modeling Contamination Migration on the Chandra X-Ray Observatory - III

    Science.gov (United States)

    O'Dell, Stephen L.; Swartz, Douglas A.; Tice, Neil W.; Plucinsky, Paul P.; Grant, Catherine E.; Marshall, Herman L.; Vikhlinin, Alexy A.; Tennant, Allyn F.; Dahmer, Matthew T.

    2015-01-01

    During its first 16 years of operation, the cold (about -60 C) optical blocking filter of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination that attenuates low-energy x rays. Over the past few years, the accumulation rate, spatial distribution, and composition have changed. This evolution has motivated further analysis of contamination migration within and near the ACIS cavity, in part to evaluate potential bake-out scenarios intended to reduce the level of contamination. Keywords: X-ray astronomy, CCDs, contamination, modeling and simulation, spacecraft operations

  18. In vitro model to study cocaine and its contaminants.

    Science.gov (United States)

    Steinmetz, Aline; Steffens, Luiza; Morás, Ana Moira; Prezzi, Flávia; Braganhol, Elizandra; Saffi, Jenifer; Ortiz, Rafael Scorsatto; Barros, Helena M T; Moura, Dinara Jaqueline

    2018-04-01

    Cocaine is one of the most popular illicit drug worldwide. Due its great addictive potential, which leads to euphoria and hyperactivity, it is considered a public health concern. At the central nervous system, the drug acts inhibiting catecholamine re-uptake. It is now known that in addition to the toxicity of the drug itself, the contaminants present in the street drug have raised concern about the harmful effects on health. Toxicological in vivo and in vitro studies have demonstrated the toxic effects of cocaine correlated with the generation of reactive oxygen species (ROS), which in turn lead to oxidative damage to the cells. Therefore the aim of this work was to propose an in vitro model that reunites the main parameters of toxicity of the cocaine already observed in the literature so far, and we tested this model using cocaine and seizure cocaine sample (SCS), kindly provided by Federal Police of Brazil. For that, we used a C6 glioblastoma cells and evaluated cell death, oxygen reactive species induction, oxidation of macromolecules as membrane lipids and DNA and loss of mitochondrial membrane potential after cocaine exposure. The results showed that cocaine can decrease cellular viability in a dose-dependent way in the C6 cell immortalized and astrocytes primary culture. Cocaine also induced cellular death by apoptosis. However, in the seizure cocaine sample (SCS), the predominant cell death was due to necrosis. Using dichlorofluorescein (DCF) assay, we confirmed ROS production after cocaine exposition. In agreement with these findings, occurred an increasing in MDA production, as well as increased superoxide dismutase (SOD) and catalase (CAT) activity. The induction of DNA damage was observed after cocaine. Our results demonstrate the occurrence of mitochondrial dysfunction by depolarization of mitochondrial membrane as a consequence of cocaine treatment. In summary, these results demonstrated that cocaine can induce reactive oxygen species formation

  19. Compartment model for long-term contamination prediction in deciduous fruit trees after a nuclear accident

    International Nuclear Information System (INIS)

    Antonopoulos-Domis, M.; Clouvas, A.; Gagianas, A.

    1990-01-01

    Radiocesium contamination from the Chernobyl accident of different parts (fruits, leaves, and shoots) of selected apricot trees in North Greece was systematically measured in 1987 and 1988. The results are presented and discussed in the framework of a simple compartment model describing the long-term contamination uptake mechanism of deciduous fruit trees after a nuclear accident

  20. Improving farm management by modeling the contamination of farm tank milk with butyric acid bacteria

    NARCIS (Netherlands)

    Vissers, M.M.M.; Driehuis, F.; Giffel, te M.C.; Jong, de P.; Lankveld, J.M.G.

    2006-01-01

    Control of contamination of farm tank milk (FTM) with the spore-forming butyric acid bacteria (BAB) is important to prevent the late-blowing defect in semi-hard cheeses. The risk of late blowing can be decreased via control of the contamination level of FTM with BAB. A modeling approach was applied

  1. EVALUATION OF THE STATE-OF-THE-ART CONTAMINATED SEDIMENT TRANSPORT AND FATE MODELING SYSTEM

    Science.gov (United States)

    Modeling approaches for evaluating the transport and fate of sediment and associated contaminants are briefly reviewed. The main emphasis is on: 1) the application of EFDC (Environmental Fluid Dynamics Code), the state-of-the-art contaminated sediment transport and fate public do...

  2. Mathematically aided risk assessment of crude oil contamination in Ogoni, Nigeria. Pt. 3. Spatial model of the multiple contamination

    Energy Technology Data Exchange (ETDEWEB)

    Thiergaertner, Hannes [Free Univ. Berlin (Germany). Faculty of Geosciences; Holtzmann, Kay

    2012-03-15

    Mathematical modeling can support environmental risk assessment and decision making processes. Soil contamination caused by crude oil in the Ogoni region, Nigeria, is described in detail in part 1 to understand expected mathematical results. A mathematical-statistical analysis following in part 2 characterizes 33 contaminated sites as entire ecological complex. The sites are studied in part 3 by multivariate classifying models to derive precise information about kind and degree of contamination at every studied location. The 33 sites were studied by multivariate heuristic classifying methods (cluster analyses). Resulting classes or groups include all samples which are similar with respect to their pollution. The amount of 665 analyzed samples was reduced to 28 classes distinguishable by kind and degree of pollution. Mutual relationships between the classes were visualized by dendrograms. The calculated averaged properties of each class have been attached to any sample belonging to a class. Additionally, the geographic origin and depth of each sample was introduced to localize the pollution. The cluster membership of any sample can be marked by symbolic colors and visualized in mini-profiles which were drawn into geographic layers. Four sites in Ogoni have been selected to show and to discuss the result. (orig.)

  3. Modeling to Support Groundwater Contaminant Boundaries for the Shoal Underground Nuclear Test

    Energy Technology Data Exchange (ETDEWEB)

    K. Pohlmann; G. Pohll; J. Chapman; A. Hassan; R. Carroll; C. Shirley

    2004-03-01

    The purpose of this work is to characterize groundwater flow and contaminant transport at the Shoal underground nuclear test through numerical modeling using site-specific hydrologic data. The ultimate objective is the development of a contaminant boundary, a model-predicted perimeter defining the extent of radionuclide-contaminated groundwater from the underground test throughout 1,000 years at a prescribed level of confidence. This boundary will be developed using the numerical models described here, after they are approved for that purpose by DOE and NDEP.

  4. Modeling to Support Groundwater Contaminant Boundaries for the Shoal Underground Nuclear Test

    International Nuclear Information System (INIS)

    K. Pohlmann; G. Pohll; J. Chapman; A. Hassan; R. Carroll; C. Shirley

    2004-01-01

    The purpose of this work is to characterize groundwater flow and contaminant transport at the Shoal underground nuclear test through numerical modeling using site-specific hydrologic data. The ultimate objective is the development of a contaminant boundary, a model-predicted perimeter defining the extent of radionuclide-contaminated groundwater from the underground test throughout 1,000 years at a prescribed level of confidence. This boundary will be developed using the numerical models described here, after they are approved for that purpose by DOE and NDEP

  5. Environmental Pathway Models-Ground-Water Modeling in Support of Remedial Decision Making at Sites Contaminated with Radioactive Material

    Science.gov (United States)

    The Joint Interagency Environmental Pathway Modeling Working Group wrote this report to promote appropriate and consistent use of mathematical environmental models in the remediation and restoration of sites contaminated by radioactive substances.

  6. Validation and Application of Models to Predict Facemask Influenza Contamination in Healthcare Settings

    Science.gov (United States)

    Fisher, Edward M.; Noti, John D.; Lindsley, William G.; Blachere, Francoise M.; Shaffer, Ronald E.

    2015-01-01

    Facemasks are part of the hierarchy of interventions used to reduce the transmission of respiratory pathogens by providing a barrier. Two types of facemasks used by healthcare workers are N95 filtering facepiece respirators (FFRs) and surgical masks (SMs). These can become contaminated with respiratory pathogens during use, thus serving as potential sources for transmission. However, because of the lack of field studies, the hazard associated with pathogen-exposed facemasks is unknown. A mathematical model was used to calculate the potential influenza contamination of facemasks from aerosol sources in various exposure scenarios. The aerosol model was validated with data from previous laboratory studies using facemasks mounted on headforms in a simulated healthcare room. The model was then used to estimate facemask contamination levels in three scenarios generated with input parameters from the literature. A second model estimated facemask contamination from a cough. It was determined that contamination levels from a single cough (≈19 viruses) were much less than likely levels from aerosols (4,473 viruses on FFRs and 3,476 viruses on SMs). For aerosol contamination, a range of input values from the literature resulted in wide variation in estimated facemask contamination levels (13–202,549 viruses), depending on the values selected. Overall, these models and estimates for facemask contamination levels can be used to inform infection control practice and research related to the development of better facemasks, to characterize airborne contamination levels, and to assist in assessment of risk from reaerosolization and fomite transfer because of handling and reuse of contaminated facemasks. PMID:24593662

  7. Evaluation of soil flushing of complex contaminated soil: An experimental and modeling simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Sung Mi; Kang, Christina S. [Department of Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of); Kim, Jonghwa [Department of Industrial Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of); Kim, Han S., E-mail: hankim@konkuk.ac.kr [Department of Environmental Engineering, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 143-701 (Korea, Republic of)

    2015-04-28

    Highlights: • Remediation of complex contaminated soil achieved by sequential soil flushing. • Removal of Zn, Pb, and heavy petroleum oils using 0.05 M citric acid and 2% SDS. • Unified desorption distribution coefficients modeled and experimentally determined. • Nonequilibrium models for the transport behavior of complex contaminants in soils. - Abstract: The removal of heavy metals (Zn and Pb) and heavy petroleum oils (HPOs) from a soil with complex contamination was examined by soil flushing. Desorption and transport behaviors of the complex contaminants were assessed by batch and continuous flow reactor experiments and through modeling simulations. Flushing a one-dimensional flow column packed with complex contaminated soil sequentially with citric acid then a surfactant resulted in the removal of 85.6% of Zn, 62% of Pb, and 31.6% of HPO. The desorption distribution coefficients, K{sub Ubatch} and K{sub Lbatch}, converged to constant values as C{sub e} increased. An equilibrium model (ADR) and nonequilibrium models (TSNE and TRNE) were used to predict the desorption and transport of complex contaminants. The nonequilibrium models demonstrated better fits with the experimental values obtained from the column test than the equilibrium model. The ranges of K{sub Ubatch} and K{sub Lbatch} were very close to those of K{sub Ufit} and K{sub Lfit} determined from model simulations. The parameters (R, β, ω, α, and f) determined from model simulations were useful for characterizing the transport of contaminants within the soil matrix. The results of this study provide useful information for the operational parameters of the flushing process for soils with complex contamination.

  8. Effects of lag and maximum growth in contaminant transport and biodegradation modeling

    International Nuclear Information System (INIS)

    Wood, B.D.; Dawson, C.N.

    1992-06-01

    The effects of time lag and maximum microbial growth on biodegradation in contaminant transport are discussed. A mathematical model is formulated that accounts for these effects, and a numerical case study is presented that demonstrates how lag influences biodegradation

  9. Modeling Chronic Versus Acute Human Risk from Contaminants in Food

    OpenAIRE

    Carriquiry, Alicia L.; Jensen, Helen H.; Nusser, S. M.

    1990-01-01

    The development of policies and regulations to address food safety concerns depends critically on appropriate assessment of health risk in foods. This paper evaluates the methods for assessing the population's exposure to a hazardous substance or contaminant in food and some aspects of the quantification of risk. We review current federal programmatic approaches to risk assessment and potential problems with these approaches. After developing procedures for estimating exposures of individuals...

  10. OEDGE modeling of plasma contamination efficiency of Ar puffing from different divertor locations in EAST

    Science.gov (United States)

    Pengfei, ZHANG; Ling, ZHANG; Zhenwei, WU; Zong, XU; Wei, GAO; Liang, WANG; Qingquan, YANG; Jichan, XU; Jianbin, LIU; Hao, QU; Yong, LIU; Juan, HUANG; Chengrui, WU; Yumei, HOU; Zhao, JIN; J, D. ELDER; Houyang, GUO

    2018-04-01

    Modeling with OEDGE was carried out to assess the initial and long-term plasma contamination efficiency of Ar puffing from different divertor locations, i.e. the inner divertor, the outer divertor and the dome, in the EAST superconducting tokamak for typical ohmic plasma conditions. It was found that the initial Ar contamination efficiency is dependent on the local plasma conditions at the different gas puff locations. However, it quickly approaches a similar steady state value for Ar recycling efficiency >0.9. OEDGE modeling shows that the final equilibrium Ar contamination efficiency is significantly lower for the more closed lower divertor than that for the upper divertor.

  11. Modelling water and contaminant transport in the Rum Jungle Mine overburden heaps

    International Nuclear Information System (INIS)

    Pantelis, G.

    1987-04-01

    An outline is given of a computer model for water and contaminant transport in and around overburden heaps, with those at the Rum Jungle mine site as a specific example. The model assumes the heaps to lie on a sloping shallow aquifer with identical hydraulic properties. The simulation is carried out for a 40 year period. After the first 20 years a cover which is effectively impermeable to infiltrating rainwater and air is introduced on the heap. The restriction of oxygen supply to the heap terminates contaminant production which results from oxidation of pyrite. Leaching of contaminants from the heap in the following 20-year period is examined

  12. Modeling phytoextraction of heavy metals at multiply contaminated soils with hyperaccumulator plants

    OpenAIRE

    Khodaverdiloo, Habib

    2009-01-01

    Soils and waters contaminated with heavy metals pose a major environmental and human health problem that needs an effective and affordable technological solution. Phytoextraction offers a reasonable technology which uses plants to extract the heavy metals from soils. However, the effectiveness of this new method needs to be demonstrated by means of mathematical modeling. The phytoextraction models also are needed to manage the contaminated soils. A thorough literature review indic...

  13. Modelling the transuranic contamination in soils by using a generic model and systematic sampling

    International Nuclear Information System (INIS)

    Breitenecker, Katharina; Brandl, Alexander; Bock, Helmut; Villa, Mario

    2008-01-01

    Full text: In the course of the decommissioning the former ASTRA Research Reactor, the Seibersdorf site is to be surveyed for possible contamination by radioactive materials, including transuranium elements. To limit costs due to systematic sampling and time consuming laboratory analyses, a mathematical model that describes the migration of transuranium elements and that includes the local topography of the area where deposition has occurred, was established.The project basis is to find a mathematical function that determines the contamination by modelling the pathways of transuranium elements. The model approach chosen is cellular automata (CA). For this purpose, a hypothetical activity of transuranium elements is released on the ground in the centre of a simulated area. Under the assumption that migration of these elements only takes place by diffusion, transport and sorption, their equations are modelled in the CA-model by a simple discretization for the existing problem. To include local topography, most of the simulated area consists of a green corridor, where migration proceeds quite slowly; streets, where the migrational behaviour is different, and migration velocities in ditches are also modelled. The Migration of three different plutonium isotopes ( 238P u, 239+240P u, 241P u), the migration of one americium isotope ( 241A m), the radioactive decay of 241P u via 241A m to 237N p and the radioactive decay of 238P u to 234U were considered in this model. Due to the special modelling approach of CA, the physical necessity of conservation of the amount of substance is always fulfilled. The entire system was implemented in MATLAB. Systematic sampling onto a featured test site, followed by detailed laboratory analyses were done to compare the underlying CA-model to real data. On this account a nuclide vector with 241A m as the reference nuclide was established. As long as the initial parameters (e.g. meteorological data) are well known, the model describes the

  14. Metal availability in a highly contaminated, dredged-sediment disposal site: field measurements and geochemical modeling.

    Science.gov (United States)

    Lions, Julie; Guérin, Valérie; Bataillard, Philippe; van der Lee, Jan; Laboudigue, Agnès

    2010-09-01

    Two complementary approaches were used to characterize arsenic and metal mobilizations from a dredged-sediment disposal site: a detailed field study combined with hydrogeochemical modeling. Contaminants in sediments were found to be mainly present as sulfides subject to oxidation. Secondary phases (carbonates, sulfates, (hydr)oxides) were also observed. Oxidative processes occurred at different rates depending on physicochemical conditions and contaminant contents in the sediment. Two distinct areas were identified on the site, each corresponding to a specific contaminant mobility behavior. In a reducing area, Fe and As were highly soluble and illustrated anoxic behavior. In well-oxygenated material, groundwater was highly contaminated in Zn, Cd and Pb. A third zone in which sediments and groundwater were less contaminated was also characterized. This study enabled us to prioritize remediation work, which should aim to limit infiltration and long-term environmental impact. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  15. Analysis of Salmonella sp bacterial contamination on Vannamei Shrimp using binary logit model approach

    Science.gov (United States)

    Oktaviana, P. P.; Fithriasari, K.

    2018-04-01

    Mostly Indonesian citizen consume vannamei shrimp as their food. Vannamei shrimp also is one of Indonesian exports comodities mainstay. Vannamei shrimp in the ponds and markets could be contaminated by Salmonella sp bacteria. This bacteria will endanger human health. Salmonella sp bacterial contamination on vannamei shrimp could be affected by many factors. This study is intended to identify what factors that supposedly influence the Salmonella sp bacterial contamination on vannamei shrimp. The researchers used the testing result of Salmonella sp bacterial contamination on vannamei shrimp as response variable. This response variable has two categories: 0 = if testing result indicate that there is no Salmonella sp on vannamei shrimp; 1 = if testing result indicate that there is Salmonella sp on vannamei shrimp. There are four factors that supposedly influence the Salmonella sp bacterial contamination on vannamei shrimp, which are the testing result of Salmonella sp bacterial contamination on farmer hand swab; the subdistrict of vannamei shrimp ponds; the fish processing unit supplied by; and the pond are in hectare. This four factors used as predictor variables. The analysis used is Binary Logit Model Approach according to the response variable that has two categories. The analysis result indicates that the factors or predictor variables which is significantly affect the Salmonella sp bacterial contamination on vannamei shrimp are the testing result of Salmonella sp bacterial contamination on farmer hand swab and the subdistrict of vannamei shrimp ponds.

  16. Contaminant fate and transport in the Venice Lagoon: results from a multi-segment multimedia model.

    Science.gov (United States)

    Sommerfreund, J K; Gandhi, N; Diamond, M L; Mugnai, C; Frignani, M; Capodaglio, G; Gerino, M; Bellucci, L G; Giuliani, S

    2010-03-01

    Contaminant loadings to the Venice Lagoon peaked from 1950s-1980s and although they have since declined, contaminant concentrations remain elevated in sediment and seafood. In order to identify the relative importance of contaminant sources, inter-media exchange and removal pathways, a modified 10-segment fugacity/aquivalence-based model was developed for octachlorodibenzodioxin/furan (OCDD/F), PCB-180, Pb and Cu in the Venice Lagoon. Results showed that in-place pollution nearby the industrial area, current industrial discharges, and tributary loadings were the main sources of contaminants to the lagoon, with negligible contributions from the atmosphere. The fate of these contaminants was governed by sediment-water exchange with simultaneous advective transport by water circulation. Contaminants circulated amongst the northern and central basins with a small fraction reaching the far southern basin and the Chioggia inlet. As a consequence, we estimated limited contaminant transfer to the Adriatic Sea, trapping the majority of contaminants in the sediment in this "average" circulation scenario which does not account for periodic flooding events. (c) 2009 Elsevier Inc. All rights reserved.

  17. Modeling the emission, transport and deposition of contaminated dust from a mine tailing site.

    Science.gov (United States)

    Stovern, Michael; Betterton, Eric A; Sáez, A Eduardo; Villar, Omar Ignacio Felix; Rine, Kyle P; Russell, Mackenzie R; King, Matt

    2014-01-01

    Mining operations are potential sources of airborne particulate metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, due to potential deleterious effects on human health and ecology. Dust emissions and dispersion of contaminants from the Iron King Mine tailings in Dewey-Humboldt, Arizona, a Superfund site, are currently being investigated through in situ field measurements and computational fluid dynamics modeling. These tailings are significantly contaminated with lead and arsenic with an average soil concentration of 1616 and 1420 ppm, respectively. Similar levels of these contaminants have also been measured in soil samples taken from the area surrounding the mine tailings. Using a computational fluid dynamics model, we have been able to model dust transport from the mine tailings to the surrounding region. The model includes a distributed Eulerian model to simulate fine aerosol transport and a Lagrangian approach to model fate and transport of larger particles. In order to improve the accuracy of the dust transport simulations both regional topographical features and local weather patterns have been incorporated into the model simulations.

  18. Hanford Site Tank 241-C-108 Residual Waste Contaminant Release Models and Supporting Data

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, Kirk J.; Krupka, Kenneth M.; Geiszler, Keith N.; Arey, Bruce W.; Schaef, Herbert T.

    2010-06-18

    This report presents the results of laboratory characterization, testing, and analysis for a composite sample (designated 20578) of residual waste collected from single-shell tank C-108 during the waste retrieval process after modified sluicing. These studies were completed to characterize concentration and form of contaminant of interest in the residual waste; assess the leachability of contaminants from the solids; and develop release models for contaminants of interest. Because modified sluicing did not achieve 99% removal of the waste, it is expected that additional retrieval processing will take place. As a result, the sample analyzed here is not expected to represent final retrieval sample.

  19. Modeling and preliminary assessment of crude oil contaminated soil in Ogoni (Nigeria)

    Energy Technology Data Exchange (ETDEWEB)

    Thiergaertner, Hannes [Free Univ. Berlin (Germany). Faculty of Geosciences; Holtzmann, Kay

    2014-07-01

    In 2010, a severe contamination of soil and groundwater caused by the production and transportation of crude oil were detected in the Ogoni area, Federal Republic of Nigeria. A linear correlation between aliphatics and aromatics and the missing link between the degree of contamination and the depth of the soil samples indicate incomplete earlier remediation activities. 665 analyzed samples were mathematically reduced to 28 contamination patterns that can be distinguished by type and degree of pollution, environmentally assessed and visualized by a quasi 3-D model. Case studies taken from the Local Government Areas Eleme, Gokana, Khana, and Tai show the methodology and results.

  20. Experimental and AI-based numerical modeling of contaminant transport in porous media

    Science.gov (United States)

    Nourani, Vahid; Mousavi, Shahram; Sadikoglu, Fahreddin; Singh, Vijay P.

    2017-10-01

    This study developed a new hybrid artificial intelligence (AI)-meshless approach for modeling contaminant transport in porous media. The key innovation of the proposed approach is that both black box and physically-based models are combined for modeling contaminant transport. The effectiveness of the approach was evaluated using experimental and real world data. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were calibrated to predict temporal contaminant concentrations (CCs), and the effect of noisy and de-noised data on the model performance was evaluated. Then, considering the predicted CCs at test points (TPs, in experimental study) and piezometers (in Myandoab plain) as interior conditions, the multiquadric radial basis function (MQ-RBF), as a meshless approach which solves partial differential equation (PDE) of contaminant transport in porous media, was employed to estimate the CC values at any point within the study area where there was no TP or piezometer. Optimal values of the dispersion coefficient in the advection-dispersion PDE and shape coefficient of MQ-RBF were determined using the imperialist competitive algorithm. In temporal contaminant transport modeling, de-noised data enhanced the performance of ANN and ANFIS methods in terms of the determination coefficient, up to 6 and 5%, respectively, in the experimental study and up to 39 and 18%, respectively, in the field study. Results showed that the efficiency of ANFIS-meshless model was more than ANN-meshless model up to 2 and 13% in the experimental and field studies, respectively.

  1. Inverse modeling of the biodegradation of emerging organic contaminants in the soil-plant system

    DEFF Research Database (Denmark)

    Hurtado, Carlos; Trapp, Stefan; Bayona, Josep M.

    2016-01-01

    Understanding the processes involved in the uptake and accumulation of organic contaminants into plants is very important to assess the possible human risk associated with. Biodegradation of emerging contaminants in plants has been observed, but kinetical studies are rare. In this study, we analyse...... experimental data on the uptake of emerging organic contaminants into lettuce derived in a greenhouse experiment. Measured soil, root and leaf concentrations from four contaminants were selected within the applicability domain of a steady-state two-compartment standard plant uptake model: bisphenol A (BPA......), carbamazepine (CBZ), triclosan (TCS) and caffeine (CAF). The model overestimated concentrations in most cases, when no degradation rates in plants were entered. Subsequently, biodegradation rates were fitted so that the measured concentrations were met.Obtained degradation kinetics are in the order, BPA

  2. A model for the derivation of new transport limits for non-fixed contamination

    International Nuclear Information System (INIS)

    Thierfeldt, S.; Lorenz, B.; Hesse, J.

    2004-01-01

    The IAEA Regulations for the Safe Transport of Radioactive Material contain requirements for contamination limits on packages and conveyances used for the transport of radioactive material. Current contamination limits for packages and conveyances under routine transport conditions have been derived from a model proposed by Fairbairn more than 40 years ago. This model has proven effective if used with pragmatism, but is based on very conservative as well as extremely simple assumptions which is in no way appropriate any more and which is not compatible with ICRP recommendations regarding radiation protection standards. Therefore, a new model has now been developed which reflects all steps of the transport process. The derivation of this model has been fostered by the IAEA by initiating a Co-ordinated Research Project. The results of the calculations using this model could be directly applied as new nuclide specific transport limits for the non-fixed contamination

  3. Model Intercomparison Study to Investigate a Dense Contaminant Plume in a Complex Hydrogeologic System

    International Nuclear Information System (INIS)

    Williams, Mark D.; Cole, Charles R.; Foley, Michael G.; Zinina, Galina A.; Zinin, Alexander I.; Vasil'Kova, Nelly A.; Samsonova, Lilia M.

    2001-01-01

    A joint Russian and U.S. model intercomparison study was undertaken for developing more realistic contaminant transport models of the Mayak Site, Southern Urals. The test problems were developed by the Russian Team based on their experience modeling contaminant migration near Lake Karachai. The intercomparison problems were designed to address lake and contaminant plume interactions, as well as river interactions and plume density effects. Different numerical codes were used. Overall there is good agreement between the results of both models. Features shown by both models include (1) the sinking of the plume below the lake, (2) the raising of the water table in the fresh water adjacent to the lake in response to the increased pressure from the dense plume, and (3) the formation of a second sinking plume in an area where evapotranspiration exceeded infiltration, thus increasing the solute concentrations above the source (i.e., lake) values

  4. A model for the derivation of new transport limits for non-fixed contamination

    Energy Technology Data Exchange (ETDEWEB)

    Thierfeldt, S. [Brenk Systemplanung GmbH, Aachen (Germany); Lorenz, B. [GNS Gesellschaft fuer Nuklearservice, Essen (Germany); Hesse, J. [RWE Power AG, Essen (Germany)

    2004-07-01

    The IAEA Regulations for the Safe Transport of Radioactive Material contain requirements for contamination limits on packages and conveyances used for the transport of radioactive material. Current contamination limits for packages and conveyances under routine transport conditions have been derived from a model proposed by Fairbairn more than 40 years ago. This model has proven effective if used with pragmatism, but is based on very conservative as well as extremely simple assumptions which is in no way appropriate any more and which is not compatible with ICRP recommendations regarding radiation protection standards. Therefore, a new model has now been developed which reflects all steps of the transport process. The derivation of this model has been fostered by the IAEA by initiating a Co-ordinated Research Project. The results of the calculations using this model could be directly applied as new nuclide specific transport limits for the non-fixed contamination.

  5. Response of rainbow trout transcriptome to model chemical contaminants

    International Nuclear Information System (INIS)

    Koskinen, Heikki; Pehkonen, Petri; Vehniaeinen, Eeva; Krasnov, Aleksei; Rexroad, Caird; Afanasyev, Sergey; Moelsa, Hannu; Oikari, Aimo

    2004-01-01

    We used high-density cDNA microarray in studies of responses of rainbow trout fry at sublethal ranges of β-naphthoflavone, cadmium, carbon tetrachloride, and pyrene. The differentially expressed genes were grouped by the functional categories of Gene Ontology. Significantly different response to the studied compounds was shown by a number of classes, such as cell cycle, apoptosis, signal transduction, oxidative stress, subcellular and extracellular structures, protein biosynthesis, and modification. Cluster analysis separated responses to the contaminants at low and medium doses, whereas at high levels the adaptive reactions were masked with general unspecific response to toxicity. We found enhanced expression of many mitochondrial proteins as well as genes involved in metabolism of metal ions and protein biosynthesis. In parallel, genes related to stress and immune response, signal transduction, and nucleotide metabolism were down-regulated. We performed computer-assisted analyses of Medline abstracts retrieved for each compound, which helped us to indicate the expected and novel findings

  6. Modelling of flow and contaminant migration in single rock fractures

    International Nuclear Information System (INIS)

    Dahlblom, P.; Joensson, L.

    1990-03-01

    The report deals with flow and hydrodynamic dispersion of a nonreactive contaminant in a single, irregularly shaped fracture. The main purpose of the report is to describe the basis and development of a computational 'tool' for simulating the aperture geometry of a single fracture and the detailed flow in it. On the basis of this flow information further properties of the fracture can be studied. Some initial application to dispersion of a nonreactive contaminant are thus discussed. The spatial pattern of variation of the fracture aperture is considered as a two-dimensional stochastic process. A method for simulation of such a process is described. The stochastic properties can be chosen arbitrarily. It is assumed that the fracture aperture belongs to a log-normal distribution. For calculation of the flow pattern, the Navier-Stokes equations are simplified to describe low velocity and steady-state flow. These equations, and the continuity equation are integrated in the direction across the fracture plane. A stream function, which describes the integrated flow in the fracture, is defined. A second order partial differential equation, with respect to the stream function, is established and solved by the finite difference method. Isolines for the stream function define boundaries between channels with equal flow rates. The travel time for each channel can be calculated to achieve a measure of the dispersion. The impact of the aperture distribution on the ratio between the mass balance fracture aperture and the cubic law fracture aperture is shown by simple examples. (28 figs., 1 tab., 22 refs.)

  7. Model for evaluation of the radiological exposure in an urban environment after a radioactive contamination

    International Nuclear Information System (INIS)

    Rochedo, Elaine Rua Rodriguez

    1994-08-01

    A dynamic model aimed on the assessment of the long-term consequences of an accidental contamination of an urban environments has been developed. The model was designed to assess the radiation exposure, as a function of time, of the different kinds of people that uses the contaminated environment, the relative contribution of each exposure pathway and to simulate the application of countermeasures and its effects on the reduction of surfaces contamination and on the exposure of the individuals and of the population. The model is an empirical one, mainly based on environmental data gathered after the Chernobyl and Goiania accidents, and takes into account climatic and population habits characteristic of tropical areas. The model was applied here to a contamination with the radionuclide 137 Cs but can be easily adapted to other nuclides by changes on parameter values. An analysis of the variabilities associated to the model outputs regarding population habits, different kinds of urban environment and parameters uncertainty has shown that the main source of uncertainty on model predictions is associated to a correct knowledge of population characteristics, its habits and used of the contaminated environment. (author)

  8. Combined local and systemic antibiotic delivery improves eradication of wound contamination: An animal experimental model of contaminated fracture.

    Science.gov (United States)

    Rand, B C C; Penn-Barwell, J G; Wenke, J C

    2015-10-01

    Systemic antibiotics reduce infection in open fractures. Local delivery of antibiotics can provide higher doses to wounds without toxic systemic effects. This study investigated the effect on infection of combining systemic with local antibiotics via polymethylmethacrylate (PMMA) beads or gel delivery. An established Staphylococcus aureus contaminated fracture model in rats was used. Wounds were debrided and irrigated six hours after contamination and animals assigned to one of three groups, all of which received systemic antibiotics. One group had local delivery via antibiotic gel, another PMMA beads and the control group received no local antibiotics. After two weeks, bacterial levels were quantified. Combined local and systemic antibiotics were superior to systemic antibiotics alone at reducing the quantity of bacteria recoverable from each group (p = 0.002 for gel; p = 0.032 for beads). There was no difference in the bacterial counts between bead and gel delivery (p = 0.62). These results suggest that local antibiotics augment the antimicrobial effect of systemic antibiotics. Although no significant difference was found between vehicles, gel delivery offers technical advantages with its biodegradable nature, ability to conform to wound shape and to deliver increased doses. Further study is required to see if the gel delivery system has a clinical role. ©2015 The British Editorial Society of Bone & Joint Surgery.

  9. Importance of exposure model in estimating impacts when a water distribution system is contaminated

    International Nuclear Information System (INIS)

    Davis, M. J.; Janke, R.; Environmental Science Division; USEPA

    2008-01-01

    The quantity of a contaminant ingested by individuals using tap water drawn from a water distribution system during a contamination event depends on the concentration of the contaminant in the water and the volume of water ingested. If the concentration varies with time, the actual time of exposure affects the quantity ingested. The influence of the timing of exposure and of individual variability in the volume of water ingested on estimated impacts for a contamination event has received limited attention. We examine the significance of ingestion timing and variability in the volume of water ingested by using a number of models for ingestion timing and volume. Contaminant concentrations were obtained from simulations of an actual distribution system for cases involving contaminant injections lasting from 1 to 24 h. We find that assumptions about exposure can significantly influence estimated impacts, especially when injection durations are short and impact thresholds are high. The influence of ingestion timing and volume should be considered when assessing impacts for contamination events

  10. A nonequilibrium model for reactive contaminant transport through fractured porous media: Model development and semianalytical solution

    Science.gov (United States)

    Joshi, Nitin; Ojha, C. S. P.; Sharma, P. K.

    2012-10-01

    In this study a conceptual model that accounts for the effects of nonequilibrium contaminant transport in a fractured porous media is developed. Present model accounts for both physical and sorption nonequilibrium. Analytical solution was developed using the Laplace transform technique, which was then numerically inverted to obtain solute concentration in the fracture matrix system. The semianalytical solution developed here can incorporate both semi-infinite and finite fracture matrix extent. In addition, the model can account for flexible boundary conditions and nonzero initial condition in the fracture matrix system. The present semianalytical solution was validated against the existing analytical solutions for the fracture matrix system. In order to differentiate between various sorption/transport mechanism different cases of sorption and mass transfer were analyzed by comparing the breakthrough curves and temporal moments. It was found that significant differences in the signature of sorption and mass transfer exists. Applicability of the developed model was evaluated by simulating the published experimental data of Calcium and Strontium transport in a single fracture. The present model simulated the experimental data reasonably well in comparison to the model based on equilibrium sorption assumption in fracture matrix system, and multi rate mass transfer model.

  11. Modeling to Support Groundwater Contaminant Boundaries for the Shoal Underground Nuclear Test

    Energy Technology Data Exchange (ETDEWEB)

    K. Pohlmann; G. Pohll; J. Chapman; A. Hassan; R. Carroll; C. Shirley

    2004-03-01

    Groundwater flow and radionuclide transport at the Shoal underground nuclear test are characterized using three-dimensional numerical models, based on site-specific hydrologic data. The objective of this modeling is to provide the flow and transport models needed to develop a contaminant boundary defining the extent of radionuclide-contaminated groundwater at the site throughout 1,000 years at a prescribed level of confidence. This boundary will then be used to manage the Project Shoal Area for the protection of the public and the environment.

  12. Modeling Contamination Migration on the Chandra X-ray Observatory - II

    Science.gov (United States)

    O'Dell, Stephen L.; Swartz, Douglas A.; Tice, Neil W.; Plucinsky, Paul P.; Grant, Catherine E.; Marshall, Herman L.; Vikhlinin, Alexey A.; Tennant, Allyn F.

    2013-01-01

    During its first 14 years of operation, the cold (about -60C) optical blocking filter of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination that attenuates low-energy x rays. Over the past few years, the accumulation rate, spatial distribution, and composition have changed. This evolution has motivated further analysis of contamination migration within and near the ACIS cavity. To this end, the current study employs a higher-fidelity geometric model of the ACIS cavity, detailed thermal modeling based upon temperature data, and a refined model of the molecular transport.

  13. Unsaturated zone leaching models for assessing risk to groundwater of contaminated sites

    DEFF Research Database (Denmark)

    Troldborg, Mads; Binning, Philip John; Nielsen, Signe

    2009-01-01

    and aqueous phase contaminant transport equation. The equation has the same general form as the standard advection-diffusion equation for which many analytical solutions have been derived. Four new analytical solutions are developed using this approach: a three-dimensional solution accounting for infiltration......, lateral gas diffusion, sorption and degradation; a simple one-dimensional screening model, and two one-dimensional radial gas diffusion models for use in simulating volatile organic contaminant diffusion in unsaturated soils with an impermeable cover. The models show that both degradation and diffusion...

  14. Hanford tank residual waste - Contaminant source terms and release models

    International Nuclear Information System (INIS)

    Deutsch, William J.; Cantrell, Kirk J.; Krupka, Kenneth M.; Lindberg, Michael L.; Jeffery Serne, R.

    2011-01-01

    Highlights: → Residual waste from five Hanford spent fuel process storage tanks was evaluated. → Gibbsite is a common mineral in tanks with high Al concentrations. → Non-crystalline U-Na-C-O-P ± H phases are common in the U-rich residual. → Iron oxides/hydroxides have been identified in all residual waste samples. → Uranium release is highly dependent on waste and leachant compositions. - Abstract: Residual waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy's Hanford Site in Washington State, USA. In the long term, the residual wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, residual waste from five tanks has been evaluated. Residual wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while residual wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2-29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low ( 2 -saturated solution, or a CaCO 3 -saturated water. Uranium release concentrations are highly dependent on waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U residual wastes, and also higher when leached with the CaCO 3 -saturated solution than with the Ca(OH) 2 -saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the waste, and it appears to be slightly more leachable by the Ca(OH) 2 -saturated solution than by the CaCO 3 -saturated solution. In general, Tc is much less leachable (<10 wt.% of the

  15. Finite element modeling of contaminant transport in soils including the effect of chemical reactions.

    Science.gov (United States)

    Javadi, A A; Al-Najjar, M M

    2007-05-17

    The movement of chemicals through soils to the groundwater is a major cause of degradation of water resources. In many cases, serious human and stock health implications are associated with this form of pollution. Recent studies have shown that the current models and methods are not able to adequately describe the leaching of nutrients through soils, often underestimating the risk of groundwater contamination by surface-applied chemicals, and overestimating the concentration of resident solutes. Furthermore, the effect of chemical reactions on the fate and transport of contaminants is not included in many of the existing numerical models for contaminant transport. In this paper a numerical model is presented for simulation of the flow of water and air and contaminant transport through unsaturated soils with the main focus being on the effects of chemical reactions. The governing equations of miscible contaminant transport including advection, dispersion-diffusion and adsorption effects together with the effect of chemical reactions are presented. The mathematical framework and the numerical implementation of the model are described in detail. The model is validated by application to a number of test cases from the literature and is then applied to the simulation of a physical model test involving transport of contaminants in a block of soil with particular reference to the effects of chemical reactions. Comparison of the results of the numerical model with the experimental results shows that the model is capable of predicting the effects of chemical reactions with very high accuracy. The importance of consideration of the effects of chemical reactions is highlighted.

  16. Performance testing of the sediment-contaminant transport model, SERATRA, at different rivers

    International Nuclear Information System (INIS)

    Onishi, Y.; Yabusaki, S.B.; Kincaid, C.T.

    1982-04-01

    Mathematical models of sediment-contaminant migration in surface water must account for transport, intermedia transfer, decay and degradation, and transformation processes. The unsteady, two dimensional, sediment-contaminant transport code, SERATRA (Onishi, Schreiber and Codell 1980) includes these mechanisms. To assess the accuracy of SERATRA to simulate the sediment-contaminant transport and fate processes, the code was tested against one-dimensional analytical solutions, checked for its mass balance, and applied to field sites. The field application cases ranged from relatively simple, steady conditions to unsteady, nonuniform conditions for large, intermediate, and small rivers. It was found that SERATRA is capable of simulating sediment-contaminant transport under a wide range of conditions

  17. A coupled classification - evolutionary optimization model for contamination event detection in water distribution systems.

    Science.gov (United States)

    Oliker, Nurit; Ostfeld, Avi

    2014-03-15

    This study describes a decision support system, alerts for contamination events in water distribution systems. The developed model comprises a weighted support vector machine (SVM) for the detection of outliers, and a following sequence analysis for the classification of contamination events. The contribution of this study is an improvement of contamination events detection ability and a multi-dimensional analysis of the data, differing from the parallel one-dimensional analysis conducted so far. The multivariate analysis examines the relationships between water quality parameters and detects changes in their mutual patterns. The weights of the SVM model accomplish two goals: blurring the difference between sizes of the two classes' data sets (as there are much more normal/regular than event time measurements), and adhering the time factor attribute by a time decay coefficient, ascribing higher importance to recent observations when classifying a time step measurement. All model parameters were determined by data driven optimization so the calibration of the model was completely autonomic. The model was trained and tested on a real water distribution system (WDS) data set with randomly simulated events superimposed on the original measurements. The model is prominent in its ability to detect events that were only partly expressed in the data (i.e., affecting only some of the measured parameters). The model showed high accuracy and better detection ability as compared to previous modeling attempts of contamination event detection. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Grand challenge problems in environmental modeling and remediation: groundwater contaminant transport

    Energy Technology Data Exchange (ETDEWEB)

    Todd Arbogast; Steve Bryant; Clint N. Dawson; Mary F. Wheeler

    1998-08-31

    This report describes briefly the work of the Center for Subsurface Modeling (CSM) of the University of Texas at Austin (and Rice University prior to September 1995) on the Partnership in Computational Sciences Consortium (PICS) project entitled Grand Challenge Problems in Environmental Modeling and Remediation: Groundwater Contaminant Transport.

  19. Importance of hydrological parameters in contaminant transport modeling in a terrestrial environment

    International Nuclear Information System (INIS)

    Tsuduki, Katsunori; Matsunaga, Takeshi

    2007-01-01

    A grid type multi-layered distributed parameter model for calculating discharge in a watershed was described. Model verification with our field observation resulted in different sets of hydrological parameter values, all of which reproduced the observed discharge. The effect of those varied hydrological parameters on contaminant transport calculation was examined and discussed by simulation of event water transfer. (author)

  20. A Bayesian belief network approach for assessing uncertainty in conceptual site models at contaminated sites

    Science.gov (United States)

    Thomsen, Nanna I.; Binning, Philip J.; McKnight, Ursula S.; Tuxen, Nina; Bjerg, Poul L.; Troldborg, Mads

    2016-05-01

    A key component in risk assessment of contaminated sites is in the formulation of a conceptual site model (CSM). A CSM is a simplified representation of reality and forms the basis for the mathematical modeling of contaminant fate and transport at the site. The CSM should therefore identify the most important site-specific features and processes that may affect the contaminant transport behavior at the site. However, the development of a CSM will always be associated with uncertainties due to limited data and lack of understanding of the site conditions. CSM uncertainty is often found to be a major source of model error and it should therefore be accounted for when evaluating uncertainties in risk assessments. We present a Bayesian belief network (BBN) approach for constructing CSMs and assessing their uncertainty at contaminated sites. BBNs are graphical probabilistic models that are effective for integrating quantitative and qualitative information, and thus can strengthen decisions when empirical data are lacking. The proposed BBN approach facilitates a systematic construction of multiple CSMs, and then determines the belief in each CSM using a variety of data types and/or expert opinion at different knowledge levels. The developed BBNs combine data from desktop studies and initial site investigations with expert opinion to assess which of the CSMs are more likely to reflect the actual site conditions. The method is demonstrated on a Danish field site, contaminated with chlorinated ethenes. Four different CSMs are developed by combining two contaminant source zone interpretations (presence or absence of a separate phase contamination) and two geological interpretations (fractured or unfractured clay till). The beliefs in each of the CSMs are assessed sequentially based on data from three investigation stages (a screening investigation, a more detailed investigation, and an expert consultation) to demonstrate that the belief can be updated as more information

  1. Modelling of electron contamination in clinical photon beams for Monte Carlo dose calculation

    International Nuclear Information System (INIS)

    Yang, J; Li, J S; Qin, L; Xiong, W; Ma, C-M

    2004-01-01

    The purpose of this work is to model electron contamination in clinical photon beams and to commission the source model using measured data for Monte Carlo treatment planning. In this work, a planar source is used to represent the contaminant electrons at a plane above the upper jaws. The source size depends on the dimensions of the field size at the isocentre. The energy spectra of the contaminant electrons are predetermined using Monte Carlo simulations for photon beams from different clinical accelerators. A 'random creep' method is employed to derive the weight of the electron contamination source by matching Monte Carlo calculated monoenergetic photon and electron percent depth-dose (PDD) curves with measured PDD curves. We have integrated this electron contamination source into a previously developed multiple source model and validated the model for photon beams from Siemens PRIMUS accelerators. The EGS4 based Monte Carlo user code BEAM and MCSIM were used for linac head simulation and dose calculation. The Monte Carlo calculated dose distributions were compared with measured data. Our results showed good agreement (less than 2% or 2 mm) for 6, 10 and 18 MV photon beams

  2. Hierarchical Bayesian models to assess between- and within-batch variability of pathogen contamination in food.

    Science.gov (United States)

    Commeau, Natalie; Cornu, Marie; Albert, Isabelle; Denis, Jean-Baptiste; Parent, Eric

    2012-03-01

    Assessing within-batch and between-batch variability is of major interest for risk assessors and risk managers in the context of microbiological contamination of food. For example, the ratio between the within-batch variability and the between-batch variability has a large impact on the results of a sampling plan. Here, we designed hierarchical Bayesian models to represent such variability. Compatible priors were built mathematically to obtain sound model comparisons. A numeric criterion is proposed to assess the contamination structure comparing the ability of the models to replicate grouped data at the batch level using a posterior predictive loss approach. Models were applied to two case studies: contamination by Listeria monocytogenes of pork breast used to produce diced bacon and contamination by the same microorganism on cold smoked salmon at the end of the process. In the first case study, a contamination structure clearly exists and is located at the batch level, that is, between batches variability is relatively strong, whereas in the second a structure also exists but is less marked. © 2012 Society for Risk Analysis.

  3. Using model-based screening to help discover unknown environmental contaminants.

    Science.gov (United States)

    McLachlan, Michael S; Kierkegaard, Amelie; Radke, Michael; Sobek, Anna; Malmvärn, Anna; Alsberg, Tomas; Arnot, Jon A; Brown, Trevor N; Wania, Frank; Breivik, Knut; Xu, Shihe

    2014-07-01

    Of the tens of thousands of chemicals in use, only a small fraction have been analyzed in environmental samples. To effectively identify environmental contaminants, methods to prioritize chemicals for analytical method development are required. We used a high-throughput model of chemical emissions, fate, and bioaccumulation to identify chemicals likely to have high concentrations in specific environmental media, and we prioritized these for target analysis. This model-based screening was applied to 215 organosilicon chemicals culled from industrial chemical production statistics. The model-based screening prioritized several recognized organosilicon contaminants and generated hypotheses leading to the selection of three chemicals that have not previously been identified as potential environmental contaminants for target analysis. Trace analytical methods were developed, and the chemicals were analyzed in air, sewage sludge, and sediment. All three substances were found to be environmental contaminants. Phenyl-tris(trimethylsiloxy)silane was present in all samples analyzed, with concentrations of ∼50 pg m(-3) in Stockholm air and ∼0.5 ng g(-1) dw in sediment from the Stockholm archipelago. Tris(trifluoropropyl)trimethyl-cyclotrisiloxane and tetrakis(trifluoropropyl)tetramethyl-cyclotetrasiloxane were found in sediments from Lake Mjøsa at ∼1 ng g(-1) dw. The discovery of three novel environmental contaminants shows that models can be useful for prioritizing chemicals for exploratory assessment.

  4. Field validation of the contaminant transport model, FEMA

    International Nuclear Information System (INIS)

    Wong, K.-F.V.

    1986-01-01

    The work describes the validation with field data of a finite element model of material transport through aquifers (FEMA). Field data from the Idaho Chemical Processing Plant, Idaho, USA and from the 58th Street landfill in Miami, Florida, USA are used. In both cases the model was first calibrated and then integrated over a span of eight years to check on the predictive capability of the model. Both predictive runs gave results that matched well with available data. (author)

  5. Modeling Contamination Migration on the Chandra X-ray Observatory II

    Science.gov (United States)

    O'Dell, Steve; Swartz, Doug; Tice, Neil; Plucinsky, Paul; Grant, Catherine; Marshall, Herman; Vikhlinin, Alexey

    2013-01-01

    During its first 14 years of operation, the cold (about -60degC) optical blocking filter of the Advanced CCD Imaging Spectrometer (ACIS), aboard the Chandra X-ray Observatory, has accumulated a growing layer of molecular contamination that attenuates low-energy x rays. Over the past few years, the accumulation rate, spatial distribution, and composition may have changed, perhaps partially related to changes in the operating temperature of the ACIS housing. This evolution of the accumulation of the molecular contamination has motivated further analysis of contamination migration on the Chandra X-ray Observatory, particularly within and near the ACIS cavity. To this end, the current study employs a higher-fidelity geometric model of the ACIS cavity, detailed thermal modeling based upon monitored temperature data, and an accordingly refined model of the molecular transport.

  6. Model of external exposure of population living in the areas subjected to radioactive contamination

    International Nuclear Information System (INIS)

    Golikov, V.Yu.; Balonov, M.I.

    2002-01-01

    In the paper, we formulated the general approach to assessment of external doses to population living in contaminated areas (the model equation and the set of parameters). The model parameters were assessed on the basis of results of monitoring in the environment, phantom experiments, and social and demographic information obtained on the contaminated areas. Verification of model assessments performed by comparison with measurement results of individual external doses in inhabitants within the thermoluminescent dosimetry method have shown that differences in dose assessments within both methods does not exceed 1.5 times at a confidence level of 95%. In the paper, we present the results illustrating specific features of external dose formation in population living in the areas of Russia subjected to radioactive contamination due to nuclear tests at the Semipalatinsk test site, radioactive releases from the Mayak enterprise, and the Chernobyl accident. (author)

  7. A Mathematical Model for Pathogen Cross-Contamination Dynamics during the Postharvest Processing of Leafy Greens.

    Science.gov (United States)

    Mokhtari, Amir; Oryang, David; Chen, Yuhuan; Pouillot, Regis; Van Doren, Jane

    2018-01-08

    We developed a probabilistic mathematical model for the postharvest processing of leafy greens focusing on Escherichia coli O157:H7 contamination of fresh-cut romaine lettuce as the case study. Our model can (i) support the investigation of cross-contamination scenarios, and (ii) evaluate and compare different risk mitigation options. We used an agent-based modeling framework to predict the pathogen prevalence and levels in bags of fresh-cut lettuce and quantify spread of E. coli O157:H7 from contaminated lettuce to surface areas of processing equipment. Using an unbalanced factorial design, we were able to propagate combinations of random values assigned to model inputs through different processing steps and ranked statistically significant inputs with respect to their impacts on selected model outputs. Results indicated that whether contamination originated on incoming lettuce heads or on the surface areas of processing equipment, pathogen prevalence among bags of fresh-cut lettuce and batches was most significantly impacted by the level of free chlorine in the flume tank and frequency of replacing the wash water inside the tank. Pathogen levels in bags of fresh-cut lettuce were most significantly influenced by the initial levels of contamination on incoming lettuce heads or surface areas of processing equipment. The influence of surface contamination on pathogen prevalence or levels in fresh-cut bags depended on the location of that surface relative to the flume tank. This study demonstrates that developing a flexible yet mathematically rigorous modeling tool, a "virtual laboratory," can provide valuable insights into the effectiveness of individual and combined risk mitigation options. © 2018 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

  8. A model for evaluating the radioactive contamination in the urban environment

    International Nuclear Information System (INIS)

    Hwang, Won Tae; Kim, Eun Han; Jeong, Hyo Joon; Suh, Kyung Suk; Han, Moon Hee

    2005-01-01

    A model for evaluating radioactive contamination in the urban environment, named METRO-K, was developed as a basic step for accident consequence analysis in case of an accidental release. The three kind of radionuclides ( 137 Cs, 106 Ru, 131 I) and the different chemical forms of iodine (particulate, organic and elemental forms) are considered in the model. The radioactive concentrations are evaluated for the five types of surface (roof, paved road, wall, lawn/soil, tree) as a function of time. Using the model, the contaminative impacts of the surfaces were intensively investigated with respect to with and without precipitation during the measurement periods of radionuclides in air. In addition, a practical application study was conducted using 137 Cs concentration in air and precipitation measured in an European country at the Chernobyl accident. As a result, precipitation was an influential factor in surface contamination. The degree of contamination was strongly dependent on the types of radionuclide and surface. Precipitation was more influential in contamination of 137 Cs than that of 131 I (elemental form)

  9. Numerical Speadsheet Modeling of Natural Attenuation for Groundwater Contaminant Plumes

    National Research Council Canada - National Science Library

    Twesme, Troy

    1999-01-01

    .... The model was used to evaluate natural attenuation for removal of a trichloroethylene (TCE) plume from a surficial aquifer containing three regions with distinctly different processes for degradation of TCE...

  10. The peculiarity of the models of the contamination's migration in water in the Chernobyl region

    International Nuclear Information System (INIS)

    Kononovich, A.L.; Krishev, I.I.; Oskolkov, B.Ja.; Kulebakina, L.G.; Arhipov, N.P.

    1997-01-01

    The new factors become significant for Chernobyl's contamination's evolution after 8-10 years. Those factors were hidden in the early 3-5 years. Our paper describes the mathematical model of the migration's process of the radionuclides in Chernobyl cooling pond and some results about the migration of the 137 Cs by groundwater. Our model for radionuclide's migration in the Chernobyl cooling pond differ from other mathematical models, that it takes into account the destruction of the fuel's particles during the time. It shows increased concentration of the 90 Sr in water and the monotonous decrease 137 Cs concentration in water. The results of the model's calculation of the annual concentration of the 137 Cs and 90 Sr in water coincide with measurements results in less than 20%. It is the only model of the Chernobyl cooling pond, which has so good coincidence during 10 years. Result of this work shows that the main process, which determines the time's dependence of the annual concentration of the radionuclides in Chernobyl cooling pond, is the destruction of the fuel's particles. In the second part of the paper there is result of the investigation 137 Cs migration by groundwater. The investigation was made with combination of the physical's modelling and mathematical's modelling methods. Truer is discussion about similarity of the physical-chemical simulation and real process. We had investigated the real Chernobyl's ground's contamination in the physical-chemical's similar model's system. It has observed the fraction of the 137 Cs in groundwater's contamination with very low sorption's coefficient, and thus the big migration's velocity (like 90 Sr). The part of the speed component is about 10 -4 . But the components of 137 Cs contamination, which has the big sorption's coefficient, converts slowly into the 'speed form' during the time. We had no see any publication about 'speed component' of 137 Cs contamination in Chernobyl's groundwater. All contemporary models of

  11. Analytical model of contamination during the drying of cylinders of jamonable muscle

    Science.gov (United States)

    Montoya Arroyave, Isabel

    2014-05-01

    For a cylinder of jamonable muscle of radius R and length much greater than R; considering that the internal resistance to the transfer of water is much greater than the external and that the internal resistance is one certain function of the distance to the axis; the distribution of the punctual moisture in the jamonable cylinder is analytically computed in terms of the Bessel's functions. During the process of drying and salted the jamonable cylinder is sensitive to contaminate with bacterium and protozoa that come from the environment. An analytical model of contamination is presents using the diffusion equation with sources and sinks, which is solve by the method of the Laplace transform, the Bromwich integral, the residue theorem and some special functions like Bessel and Heun. The critical times intervals of drying and salted are computed in order to obtain the minimum possible contamination. It is assumed that both external moisture and contaminants decrease exponentially with time. Contaminants profiles are plotted and discussed some possible techniques of contaminants detection. All computations are executed using Computer Algebra, specifically Maple. It is said that the results are important for the food industry and it is suggested some future research lines.

  12. Dynamic modelling of Cs-137 contamination in Denmark

    International Nuclear Information System (INIS)

    Oehlenschlaeger, M.

    1989-01-01

    The paper describes the structure of a dynamic food-chain transport model for Cs-137 in the Danish terrestrial environment. The model solves a set of linear, coupled differential equations in order to estimate the inventories and concentrations of Cs-137 in the soil, vegetation, animal tissue and animal product as a function of time based on the Cs-137 concentrations in the air after an accidental release. Meteorological conditions and seasonal variations in agricultural practice are included. (orig.)

  13. Rainfall-runoff model for prediction of waterborne viral contamination in a small river catchment

    Science.gov (United States)

    Gelati, E.; Dommar, C.; Lowe, R.; Polcher, J.; Rodó, X.

    2013-12-01

    We present a lumped rainfall-runoff model aimed at providing useful information for the prediction of waterborne viral contamination in small rivers. Viral contamination of water bodies may occur because of the discharge of sewage effluents and of surface runoff over areas affected by animal waste loads. Surface runoff is caused by precipitation that cannot infiltrate due to its intensity and to antecedent soil water content. It may transport animal feces to adjacent water bodies and cause viral contamination. We model streamflow by separating it into two components: subsurface flow, which is produced by infiltrated precipitation; and surface runoff. The model estimates infiltrated and non-infiltrated precipitation and uses impulse-response functions to compute the corresponding fractions of streamflow. The developed methodologies are applied to the Glafkos river, whose catchment extends for 102 km2 and includes the city of Patra. Streamflow and precipitation observations are available at a daily time resolution. Waterborne virus concentration measurements were performed approximately every second week from the beginning of 2011 to mid 2012. Samples were taken at several locations: in river water upstream of Patras and in the urban area; in sea water at the river outlet and approximately 2 km south-west of Patras; in sewage effluents before and after treatment. The rainfall-runoff model was calibrated and validated using observed streamflow and precipitation data. The model contribution to waterborne viral contamination prediction was benchmarked by analyzing the virus concentration measurements together with the estimated surface runoff values. The presented methodology may be a first step towards the development of waterborne viral contamination alert systems. Predicting viral contamination of water bodies would benefit sectors such as water supply and tourism.

  14. External exposure model for various geometries of contaminated materials

    International Nuclear Information System (INIS)

    LePoire, D.; Kamboj, S.; Yu, C.

    1996-01-01

    A computational model for external exposure was developed for the U.S. Department of Energy's residual radioactive material guideline computer code (RESRAD) on the basis of dose coefficients from Federal Guidance Report No. 12 and the point-kernel method. This model includes the effects of different materials and exposure distances, as well as source geometry (cover thickness, source depth, area, and shape). A material factor is calculated on the basis of the point-kernel method using material-specific photon cross-section data and buildup factors. This present model was incorporated into RESRAD-RECYCLE (a RESRAD family code used for computing radiological impacts of metal recycling) and is being incorporated into RESRAD-BUILD (a DOE recommended code for computing impacts of building decontamination). The model was compared with calculations performed with the Monte Carlo N-Particle Code (MCNP) and the Microshield code for three different source geometries, three different radionuclides ( 234 U, 238 U, and 60 Co, representing low, medium, and high energy, respectively), and five different source materials (iron, copper, aluminum, water, and soil). The comparison shows that results of this model are in very good agreement with MCNP calculations (within 5% for 60 Co and within 30% for 238 U and 234 U for all materials and source geometries). Significant differences (greater than 100%) were observed with Microshield for thin 234 U sources

  15. Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer

    DEFF Research Database (Denmark)

    Mosthaf, Klaus; Fjordbøge, Annika Sidelmann; Broholm, Mette Martina

    in fractured limestone aquifers. The model comparison is conducted for a contaminated site in Denmark, where a plume of dissolved PCE has migrated through a fractured limestone aquifer. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology...... and hydrogeology. To describe the geology and fracture system, data from borehole logs and cores was combined with an analysis of heterogeneities and fractures from a nearby excavation and pump test data. We present how field data is integrated into the different model concepts. A challenge in the use of field...... and remediation strategies. Each model is compared with field data, considering both model fit and model suitability. Results show a considerable difference between the approaches, and that it is important to select the right one for the actual modeling purpose. The comparison with data showed how much...

  16. MATHEMATICAL AND CHEMOMETRICAL MODELS – TOOLS TO EVALUATE HEAVY METALS CONTAMINATION

    Directory of Open Access Journals (Sweden)

    Despina Maria Bordean

    2017-11-01

    Full Text Available The aim of the this study is to present a combined view of bio – geo - chemistry, soil – plant interactions, mathematic models and statistic analysis, based on the correlation between the levels of soil contamination, and the remanence of polluting substances in soil and respectively in harvested fruits and vegetables. Most of the mathematical models which describe plant - soil interactions are integrated in plant growth models or climate change models. The models presented by this paper are Soil – Plant Interaction Models, Pollution Indices, The Indices for Evaluating the Adaptative Strategies of Plants and Chemo-metrical Methods, and they have the role to synthesize and evaluate the information regarding heavy metals contamination.

  17. Determination of timescales of nitrate contamination by groundwater age models in a complex aquifer system

    Science.gov (United States)

    Koh, E. H.; Lee, E.; Kaown, D.; Lee, K. K.; Green, C. T.

    2017-12-01

    Timing and magnitudes of nitrate contamination are determined by various factors like contaminant loading, recharge characteristics and geologic system. Information of an elapsed time since recharged water traveling to a certain outlet location, which is defined as groundwater age, can provide indirect interpretation related to the hydrologic characteristics of the aquifer system. There are three major methods (apparent ages, lumped parameter model, and numerical model) to date groundwater ages, which differently characterize groundwater mixing resulted by various groundwater flow pathways in a heterogeneous aquifer system. Therefore, in this study, we compared the three age models in a complex aquifer system by using observed age tracer data and reconstructed history of nitrate contamination by long-term source loading. The 3H-3He and CFC-12 apparent ages, which did not consider the groundwater mixing, estimated the most delayed response time and a highest period of the nitrate loading had not reached yet. However, the lumped parameter model could generate more recent loading response than the apparent ages and the peak loading period influenced the water quality. The numerical model could delineate various groundwater mixing components and its different impacts on nitrate dynamics in the complex aquifer system. The different age estimation methods lead to variations in the estimated contaminant loading history, in which the discrepancy in the age estimation was dominantly observed in the complex aquifer system.

  18. Modeling In Situ Bioremediation of Perchlorate-Contaminated Groundwater

    Science.gov (United States)

    2007-03-01

    association between perchlorate exposure at the doses investigated and hypothyroidism or other thyroid disorders in adults Thyroid cancer in adults ...hormone secretions can result in thyroid hypertrophy and hyperplasia, possibly followed by hypothyroidism in people unable to compensate with an...perchlorate exposure. The model indicated that continued perchlorate exposure ultimately led to birth defects in children and tumors in adults . Based upon

  19. Development of a resuspension model for contaminated soils. Application to the Palomares area

    International Nuclear Information System (INIS)

    Garcia-Olivares, A.

    1993-01-01

    A model is presented which has been used to simulate the wind resuspension and transport of contaminated soil in the area surrounding the Palomares village, in Southern Spain. The model uses site specific data and some generic parameters as resuspension rate and deposition velocity. The model is able to predict the order of magnitude of the observed air concentration of activity. Some lines of research are suggested which could improve the understanding of the phenomena involved. (Author) 20 refs

  20. Development of a resupension model for contaminated soils: Application to the Palomares area

    International Nuclear Information System (INIS)

    Garcia-Olivares, A.

    1993-01-01

    A model is presented which has been used to simulate the wind resuspension and transport of contaminated soil in the area surrounding the Palomares village, in Southern Spain. The model uses site specific data and some generic parameters as resuspension rate and deposition velocity. The model is able to predict the order of magnitude of the observed air concentration of activity. Some lines of research are suggested which could improve the understanding of the phenomena involved. (author)

  1. Modeling of Faecal Contamination in Water from Catchment to Shellfish Growing Area

    OpenAIRE

    Bougeard, Morgane; Le Saux, Jean-claude; Perenne, Nicolas; Le Guyader, Soizick; Pommepuy, Monique

    2009-01-01

    During rainstorms, watersheds can introduce large amounts of faecal pollution into the rivers and sea, leading to shellfish contamination. In this study, we assessed Escherichia coli fluxes from a catchment, and their impact on estuarine water quality, using two assembled models. For the catchment, the agro-hydrological model SWAT was implemented integrating land uses, soil, topography, rainfall and other climatic data on Daoulas watershed (France). Initially, the SWAT model was calibrated an...

  2. Modeling tissue contamination to improve molecular identification of the primary tumor site of metastases

    DEFF Research Database (Denmark)

    Vincent, Martin; Perell, Katharina; Nielsen, Finn Cilius

    2014-01-01

    with any predictor model. The usability of the model is illustrated on primary tumor site identification of liver biopsies, specifically, on a human dataset consisting of microRNA expression measurements of primary tumor samples, benign liver samples and liver metastases. For a predictor trained on primary...... tumor and benign liver samples, the contamination model decreased the test error on biopsies from liver metastases from 77 to 45%. A further reduction to 34% was obtained by including biopsies in the training data....

  3. BETR global - A geographically-explicit global-scale multimedia contaminant fate model

    International Nuclear Information System (INIS)

    MacLeod, Matthew; Waldow, Harald von; Tay, Pascal; Armitage, James M.; Woehrnschimmel, Henry; Riley, William J.; McKone, Thomas E.; Hungerbuhler, Konrad

    2011-01-01

    We present two new software implementations of the BETR Global multimedia contaminant fate model. The model uses steady-state or non-steady-state mass-balance calculations to describe the fate and transport of persistent organic pollutants using a desktop computer. The global environment is described using a database of long-term average monthly conditions on a 15 o x 15 o grid. We demonstrate BETR Global by modeling the global sources, transport, and removal of decamethylcyclopentasiloxane (D5). - Two new software implementations of the Berkeley-Trent Global Contaminant Fate Model are available. The new model software is illustrated using a case study of the global fate of decamethylcyclopentasiloxane (D5).

  4. Anthropogenic contamination of a phreatic drinking water winning: 3-dimensional reactive transport modelling

    NARCIS (Netherlands)

    Griffioen, J.|info:eu-repo/dai/nl/091129265; van der Grift, B.|info:eu-repo/dai/nl/373433484; Maas, D.; van den Brink, C.|info:eu-repo/dai/nl/187443416; Zaadnoordijk, J. W.

    2003-01-01

    Groundwater is contaminated at the regional scale by agricultural activities and atmospheric deposition. A 3-D transport model was set-up for a phreatic drinking water winning, where the groundwater composition was monitored accurately. The winning is situated at an area with unconsolidated

  5. Robustness of a cross contamination model describing transfer of pathogens during grinding of meat

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm

    2016-01-01

    This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were...

  6. Robustness of a cross contamination model describing transfer of pathogens during grinding of meat

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Sant’Ana, A. S.; Hansen, Solvej Katrine Holm

    2016-01-01

    This study aimed to evaluate a cross contamination model for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were a...... that grinding was influenced by sharpness of grinder knife, specific grinder and grinding temperature....

  7. Mass Balance Model, A study of contamination effects in AMS 14C sample analysis

    NARCIS (Netherlands)

    Prokopiou, Markella

    2010-01-01

    In this training thesis a background correction analysis, also known as mass balance model, was implemented to study the contamination effects in AMS 14C sample processing. A variety of backgrounds and standards with sizes ranging from 50 μg C to 1500 μg

  8. Multi-phase flow modeling of soil contamination and soil remediation

    NARCIS (Netherlands)

    Dijke, van M.I.J.

    1997-01-01


    In this thesis multi-phase flow models are used to study the flow behavior of liquid contaminants in aquifers and of gases that are injected below the groundwater table for remediation purposes. Considered problems are redistribution of a lens of light nonaqueous phase

  9. Inverse modeling of the biodegradation of emerging organic contaminants in the soil-plant system.

    Science.gov (United States)

    Hurtado, Carlos; Trapp, Stefan; Bayona, Josep M

    2016-08-01

    Understanding the processes involved in the uptake and accumulation of organic contaminants into plants is very important to assess the possible human risk associated with. Biodegradation of emerging contaminants in plants has been observed, but kinetical studies are rare. In this study, we analyse experimental data on the uptake of emerging organic contaminants into lettuce derived in a greenhouse experiment. Measured soil, root and leaf concentrations from four contaminants were selected within the applicability domain of a steady-state two-compartment standard plant uptake model: bisphenol A (BPA), carbamazepine (CBZ), triclosan (TCS) and caffeine (CAF). The model overestimated concentrations in most cases, when no degradation rates in plants were entered. Subsequently, biodegradation rates were fitted so that the measured concentrations were met. Obtained degradation kinetics are in the order, BPA < CAF ≈ TCS < CBZ in roots, and BPA ≈ TCS < CBZ < CAF in leaves. Kinetics determined by inverse modeling are, despite the inherent uncertainty, indicative of the dissipation rates. The advantage of the procedure that is additional knowledge can be gained from existing experimental data. Dissipation kinetics found via inverse modeling is not a conclusive proof for biodegradation and confirmation by experimental studies is needed. Copyright © 2016. Published by Elsevier Ltd.

  10. Leaching of heavy metals from contaminated soils: An experimental and modeling study

    NARCIS (Netherlands)

    Dijkstra, J.J.; Meeussen, J.C.L.; Comans, R.N.J.

    2004-01-01

    In this paper, we characterize the leaching of heavy metals (Ni, Cu, Zn, Cd, and Pb) from eight contaminated soils over a wide range of pH (pH 0.4-12) using an original approach based on batch pH-static leaching experiments in combination with selective chemical extractions and geochemical modeling.

  11. Sensitivity analyses of a colloid-facilitated contaminant transport model for unsaturated heterogeneous soil conditions.

    Science.gov (United States)

    Périard, Yann; José Gumiere, Silvio; Rousseau, Alain N.; Caron, Jean

    2013-04-01

    Certain contaminants may travel faster through soils when they are sorbed to subsurface colloidal particles. Indeed, subsurface colloids may act as carriers of some contaminants accelerating their translocation through the soil into the water table. This phenomenon is known as colloid-facilitated contaminant transport. It plays a significant role in contaminant transport in soils and has been recognized as a source of groundwater contamination. From a mechanistic point of view, the attachment/detachment of the colloidal particles from the soil matrix or from the air-water interface and the straining process may modify the hydraulic properties of the porous media. Šimůnek et al. (2006) developed a model that can simulate the colloid-facilitated contaminant transport in variably saturated porous media. The model is based on the solution of a modified advection-dispersion equation that accounts for several processes, namely: straining, exclusion and attachement/detachement kinetics of colloids through the soil matrix. The solutions of these governing, partial differential equations are obtained using a standard Galerkin-type, linear finite element scheme, implemented in the HYDRUS-2D/3D software (Šimůnek et al., 2012). Modeling colloid transport through the soil and the interaction of colloids with the soil matrix and other contaminants is complex and requires the characterization of many model parameters. In practice, it is very difficult to assess actual transport parameter values, so they are often calibrated. However, before calibration, one needs to know which parameters have the greatest impact on output variables. This kind of information can be obtained through a sensitivity analysis of the model. The main objective of this work is to perform local and global sensitivity analyses of the colloid-facilitated contaminant transport module of HYDRUS. Sensitivity analysis was performed in two steps: (i) we applied a screening method based on Morris' elementary

  12. Multiphysics modelling and simulation of dry laser cleaning of micro-slots with particle contaminants

    International Nuclear Information System (INIS)

    Yue Liyang; Wang Zengbo; Li Lin

    2012-01-01

    Light could interact differently with thin-film contaminants and particle contaminates because of their different surface morphologies. In the case of dry laser cleaning of small transparent particles, it is well known that particles could function like mini-lenses, causing a localized near-field hot spot effect on the cleaning process. This paper looks into a special, yet important, phenomenon of dry laser cleaning of particles trapped in micro-sized slots. The effects of slot size, particle size and particle aggregate states in the cleaning process have been theoretically investigated, based on a coupled electromagnetic-thermal-mechanical multiphysics modelling and simulation approach. The study is important for the development and optimization of laser cleaning processes for contamination removal from cracks and slots. (paper)

  13. One-dimensional contaminant transport model for the design of soil-bentonite slurry walls

    International Nuclear Information System (INIS)

    Khandelwal, A.; Rabideau, A.; Su, J.

    1997-01-01

    A user oriented computer model (TRANS1D) was developed for application to the analysis and design of vertical soil-bentonite barriers. TRANS1D is a collection of analytical and numerical solutions to the one dimensional advective-dispersive-reactive (ADR) equation. The primary objective in developing TRANS1D was to enable the designer of a barrier system to evaluate the potential system performance with respect to contaminant transport, without performing difficult and time consuming field or laboratory experiments. Several issues related to model application are discussed, including identification of governing transport processes, specification of boundary conditions, and parameter estimation. Model predictions are compared with the results of laboratory column experiments conducted with soil bentonite barrier material under diffusion-dominated conditions. Good agreement between model calibrations and experimental results was noted, with calibrated diffusion coefficients for organic contaminants consistent with literature values

  14. Mesoscale modelling of radioactive contamination formation in Ukraine caused by the Chernobyl accident

    International Nuclear Information System (INIS)

    Talerko, Nikolai

    2005-01-01

    This work is devoted to the reconstruction of time-dependent radioactive contamination fields in the territory of Ukraine in the initial period of the Chernobyl accident using the model of atmospheric transport LEDI (Lagrangian-Eulerian DIffusion model). The modelling results were compared with available 137 Cs air and ground contamination measurement data. The 137 Cs atmospheric transport over the territory of Ukraine was simulated during the first 12 days after the accident (from 26 April to 7 May 1986) using real aerological information and rain measurement network data. The detailed scenario of the release from the accidental unit of the Chernobyl nuclear plant has been built (including time-dependent radioactivity release intensity and time-varied height of the release). The calculations have enabled to explain the main features of spatial and temporal variations of radioactive contamination fields over the territory of Ukraine on the regional scale, including the formation of the major large-scale spots of radioactive contamination caused by dry and wet deposition

  15. Model for the assessment of surface radionuclide 210 Pb contamination indoors due to presence of radon

    International Nuclear Information System (INIS)

    Mrdja, D.; Bikit, I.; Forkapic, S.

    2009-01-01

    The model is based on the fact that the change of indoor radon concentration, which periodically enters the room, affects only on radioactive decay and the inserted amount of radon in each impact, but not on its diffusion out, i.e. escape from the room. The aim of the model is to assess the surface contamination of the room by lead 210 Pb. (author) [sr

  16. Mass discharge estimation from contaminated sites: Multi-model solutions for assessment of conceptual uncertainty

    Science.gov (United States)

    Thomsen, N. I.; Troldborg, M.; McKnight, U. S.; Binning, P. J.; Bjerg, P. L.

    2012-04-01

    Mass discharge estimates are increasingly being used in the management of contaminated sites. Such estimates have proven useful for supporting decisions related to the prioritization of contaminated sites in a groundwater catchment. Potential management options can be categorised as follows: (1) leave as is, (2) clean up, or (3) further investigation needed. However, mass discharge estimates are often very uncertain, which may hamper the management decisions. If option 1 is incorrectly chosen soil and water quality will decrease, threatening or destroying drinking water resources. The risk of choosing option 2 is to spend money on remediating a site that does not pose a problem. Choosing option 3 will often be safest, but may not be the optimal economic solution. Quantification of the uncertainty in mass discharge estimates can therefore greatly improve the foundation for selecting the appropriate management option. The uncertainty of mass discharge estimates depends greatly on the extent of the site characterization. A good approach for uncertainty estimation will be flexible with respect to the investigation level, and account for both parameter and conceptual model uncertainty. We propose a method for quantifying the uncertainty of dynamic mass discharge estimates from contaminant point sources on the local scale. The method considers both parameter and conceptual uncertainty through a multi-model approach. The multi-model approach evaluates multiple conceptual models for the same site. The different conceptual models consider different source characterizations and hydrogeological descriptions. The idea is to include a set of essentially different conceptual models where each model is believed to be realistic representation of the given site, based on the current level of information. Parameter uncertainty is quantified using Monte Carlo simulations. For each conceptual model we calculate a transient mass discharge estimate with uncertainty bounds resulting from

  17. Characterization and Remediation of Contaminated Sites:Modeling, Measurement and Assessment

    Science.gov (United States)

    Basu, N. B.; Rao, P. C.; Poyer, I. C.; Christ, J. A.; Zhang, C. Y.; Jawitz, J. W.; Werth, C. J.; Annable, M. D.; Hatfield, K.

    2008-05-01

    small computation time and their inclusion of spatially integrated parameters that can be measured in the field using tracer tests. Analytical models that couple source depletion to plume transport were used for optimization of source and plume treatment. These models are being used for the development of decision and management tools (for DNAPL sites) that consider uncertainty assessments as an integral part of the decision-making process for contaminated site remediation.

  18. Investigation the Kinetic Models of Biological Removal of Petroleum Contaminated Soil Around Oil Pipeline Using Ryegrass

    Directory of Open Access Journals (Sweden)

    Elham Ghaheri

    2014-04-01

    Full Text Available The industrial revolution of the past century has resulted in significant damage to environmental resources such as air, water and soil. Petroleum contamination of soil is a serious problem throughout the oil producer countries. Remediation of petroleum contamination of soils is generally a slow and expensive process. Phytoremediation is a potentially less-damaging, cost-effective, but needs longer-term for remediation of contaminated land compared to the alternative methods. In this study the kinetics of petroleum hydrocarbon contaminated soils in Khozestan were investigated. For this paper Ryegrass (Lolium perenne plant selected and the decline of total petroleum hydrocarbon (TPH was analyzed after growth stage, every 10 days up to 90 days. The results of TPH concentration was fitted with zero-order kinetic, first-order kinetic and Higuchi model. The result indicated that degradation of TPH with presence of plants as a function of time was well fitted with the first-order kinetic model. The first-order rate constants (K and half-lives (T1/2 for TPH degradation were 0.0098 1/day and 71 day; respectively. The results of phytoremediation showed that there were 65% decreases in TPH concentration with Ryegrass during the 17 weeks.

  19. Mathematical Modeling of Non-Fickian Diffusional Mass Exchange of Radioactive Contaminants in Geological Disposal Formations

    Directory of Open Access Journals (Sweden)

    Anna Suzuki

    2018-01-01

    Full Text Available Deep geological repositories for nuclear wastes consist of both engineered and natural geologic barriers to isolate the radioactive material from the human environment. Inappropriate repositories of nuclear waste would cause severe contamination to nearby aquifers. In this complex environment, mass transport of radioactive contaminants displays anomalous behaviors and often produces power-law tails in breakthrough curves due to spatial heterogeneities in fractured rocks, velocity dispersion, adsorption, and decay of contaminants, which requires more sophisticated models beyond the typical advection-dispersion equation. In this paper, accounting for the mass exchange between a fracture and a porous matrix of complex geometry, the universal equation of mass transport within a fracture is derived. This equation represents the generalization of the previously used models and accounts for anomalous mass exchange between a fracture and porous blocks through the introduction of the integral term of convolution type and fractional derivatives. This equation can be applied for the variety of processes taking place in the complex fractured porous medium, including the transport of radioactive elements. The Laplace transform method was used to obtain the solution of the fractional diffusion equation with a time-dependent source of radioactive contaminant.

  20. A reactive transport model for mercury fate in contaminated soil--sensitivity analysis.

    Science.gov (United States)

    Leterme, Bertrand; Jacques, Diederik

    2015-11-01

    We present a sensitivity analysis of a reactive transport model of mercury (Hg) fate in contaminated soil systems. The one-dimensional model, presented in Leterme et al. (2014), couples water flow in variably saturated conditions with Hg physico-chemical reactions. The sensitivity of Hg leaching and volatilisation to parameter uncertainty is examined using the elementary effect method. A test case is built using a hypothetical 1-m depth sandy soil and a 50-year time series of daily precipitation and evapotranspiration. Hg anthropogenic contamination is simulated in the topsoil by separately considering three different sources: cinnabar, non-aqueous phase liquid and aqueous mercuric chloride. The model sensitivity to a set of 13 input parameters is assessed, using three different model outputs (volatilized Hg, leached Hg, Hg still present in the contaminated soil horizon). Results show that dissolved organic matter (DOM) concentration in soil solution and the binding constant to DOM thiol groups are critical parameters, as well as parameters related to Hg sorption to humic and fulvic acids in solid organic matter. Initial Hg concentration is also identified as a sensitive parameter. The sensitivity analysis also brings out non-monotonic model behaviour for certain parameters.

  1. Low-rank Kalman filtering for efficient state estimation of subsurface advective contaminant transport models

    KAUST Repository

    El Gharamti, Mohamad

    2012-04-01

    Accurate knowledge of the movement of contaminants in porous media is essential to track their trajectory and later extract them from the aquifer. A two-dimensional flow model is implemented and then applied on a linear contaminant transport model in the same porous medium. Because of different sources of uncertainties, this coupled model might not be able to accurately track the contaminant state. Incorporating observations through the process of data assimilation can guide the model toward the true trajectory of the system. The Kalman filter (KF), or its nonlinear invariants, can be used to tackle this problem. To overcome the prohibitive computational cost of the KF, the singular evolutive Kalman filter (SEKF) and the singular fixed Kalman filter (SFKF) are used, which are variants of the KF operating with low-rank covariance matrices. Experimental results suggest that under perfect and imperfect model setups, the low-rank filters can provide estimates as accurate as the full KF but at much lower computational effort. Low-rank filters are demonstrated to significantly reduce the computational effort of the KF to almost 3%. © 2012 American Society of Civil Engineers.

  2. Degradation modeling and experiment of electro-hydraulic shift valve in contamination circumstances

    Directory of Open Access Journals (Sweden)

    Yong Liu

    2015-05-01

    Full Text Available In this article, a degradation assessment model has been proposed for electro-hydraulic shift valve in power-shift steering transmission. Our work is motivated by the failure mechanism of abrasive wear with a mathematic model. Abrasive wear will consecutively enlarge the clearance between the friction pairs. It is an overwhelming wear mechanism in the degradation of shift valve within serious contaminated fluid. Herein, a mathematic model is proposed by considering particle morphology and abrasion theory. Such model has been verified for its applicability and accuracy through comparison between the theoretical and experimental results.

  3. Numerical modeling of contaminant transport in fractured porous media using mixed finite-element and finitevolume methods

    KAUST Repository

    Dong, Chen; Sun, Shuyu; Taylor, Glenn A.

    2011-01-01

    A mathematical model for contaminant species passing through fractured porous media is presented. In the numerical model, we combine two locally conservative methods; i.e., the mixed finite-element (MFE) method and the finite-volume method. Adaptive

  4. Agriculture and groundwater nitrate contamination in the Seine basin. The STICS-MODCOU modelling chain

    International Nuclear Information System (INIS)

    Ledoux, E.; Gomez, E.; Monget, J.M.; Viavattene, C.; Viennot, P.; Ducharne, A.; Benoit, M.; Mignolet, C.; Schott, C.; Mary, B.

    2007-01-01

    A software package is presented here to predict the fate of nitrogen fertilizers and the transport of nitrate from the rooting zone of agricultural areas to surface water and groundwater in the Seine basin, taking into account the long residence times of water and nitrate in the unsaturated and aquifer systems. Information on pedological characteristics, land use and farming practices is used to determine the spatial units to be considered. These data are converted into input data for the crop model STICS which simulates the water and nitrogen balances in the soil-plant system with a daily time-step. A spatial application of STICS has been derived at the catchment scale which computes the water and nitrate fluxes at the bottom of the rooting zone. These fluxes are integrated into a surface and groundwater coupled model MODCOU which calculates the daily water balance in the hydrological system, the flow in the rivers and the piezometric variations in the aquifers, using standard climatic data (rainfall, PET). The transport of nitrate and the evolution of nitrate contamination in groundwater and to rivers is computed by the model NEWSAM. This modelling chain is a valuable tool to predict the evolution of crop productivity and nitrate contamination according to various scenarios modifying farming practices and/or climatic changes. Data for the period 1970-2000 are used to simulate the past evolution of nitrogen contamination. The method has been validated using available data bases of nitrate concentrations in the three main aquifers of the Paris basin (Oligocene, Eocene and chalk). The approach has then been used to predict the future evolution of nitrogen contamination up to 2015. A statistical approach allowed estimating the probability of transgression of different concentration thresholds in various areas in the basin. The model is also used to evaluate the cost of the damage resulting of the treatment of drinking water at the scale of a groundwater management

  5. Agriculture and groundwater nitrate contamination in the Seine basin. The STICS-MODCOU modelling chain

    Energy Technology Data Exchange (ETDEWEB)

    Ledoux, E. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France)]. E-mail: emmanuel.ledoux@ensmp.fr; Gomez, E. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Monget, J.M. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Viavattene, C. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Viennot, P. [Centre de Geosciences, ENSMP, UMR Sisyphe, Fontainebleau (France); Ducharne, A. [Laboratoire Sisyphe, CNRS/Universite Pierre et Marie Curie, Paris (France); Benoit, M. [INRA, Station de Recherche SAD, 662 avenue Louis Buffet, 88500 Mirecourt (France); Mignolet, C. [INRA, Station de Recherche SAD, 662 avenue Louis Buffet, 88500 Mirecourt (France); Schott, C. [INRA, Station de Recherche SAD, 662 avenue Louis Buffet, 88500 Mirecourt (France); Mary, B. [INRA, Unite d' Agronomie Laon-Reims-Mons, Laon (France)

    2007-04-01

    A software package is presented here to predict the fate of nitrogen fertilizers and the transport of nitrate from the rooting zone of agricultural areas to surface water and groundwater in the Seine basin, taking into account the long residence times of water and nitrate in the unsaturated and aquifer systems. Information on pedological characteristics, land use and farming practices is used to determine the spatial units to be considered. These data are converted into input data for the crop model STICS which simulates the water and nitrogen balances in the soil-plant system with a daily time-step. A spatial application of STICS has been derived at the catchment scale which computes the water and nitrate fluxes at the bottom of the rooting zone. These fluxes are integrated into a surface and groundwater coupled model MODCOU which calculates the daily water balance in the hydrological system, the flow in the rivers and the piezometric variations in the aquifers, using standard climatic data (rainfall, PET). The transport of nitrate and the evolution of nitrate contamination in groundwater and to rivers is computed by the model NEWSAM. This modelling chain is a valuable tool to predict the evolution of crop productivity and nitrate contamination according to various scenarios modifying farming practices and/or climatic changes. Data for the period 1970-2000 are used to simulate the past evolution of nitrogen contamination. The method has been validated using available data bases of nitrate concentrations in the three main aquifers of the Paris basin (Oligocene, Eocene and chalk). The approach has then been used to predict the future evolution of nitrogen contamination up to 2015. A statistical approach allowed estimating the probability of transgression of different concentration thresholds in various areas in the basin. The model is also used to evaluate the cost of the damage resulting of the treatment of drinking water at the scale of a groundwater management

  6. A Geochemical Reaction Model for Titration of Contaminated Soil and Groundwater at the Oak Ridge Reservation

    Science.gov (United States)

    Zhang, F.; Parker, J. C.; Gu, B.; Luo, W.; Brooks, S. C.; Spalding, B. P.; Jardine, P. M.; Watson, D. B.

    2007-12-01

    This study investigates geochemical reactions during titration of contaminated soil and groundwater at the Oak Ridge Reservation in eastern Tennessee. The soils and groundwater exhibits low pH and high concentrations of aluminum, calcium, magnesium, manganese, various trace metals such as nickel and cobalt, and radionuclides such as uranium and technetium. The mobility of many of the contaminant species diminishes with increasing pH. However, base additions to increase pH are strongly buffered by various precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior and associated geochemical effects is thus critical to evaluate remediation performance of pH manipulation strategies. This study was undertaken to develop a practical but generally applicable geochemical model to predict aqueous and solid-phase speciation during soil and groundwater titration. To model titration in the presence of aquifer solids, an approach proposed by Spalding and Spalding (2001) was utilized, which treats aquifer solids as a polyprotic acid. Previous studies have shown that Fe and Al-oxyhydroxides strongly sorb dissolved Ni, U and Tc species. In this study, since the total Fe concentration is much smaller than that of Al, only ion exchange reactions associated with Al hydroxides are considered. An equilibrium reaction model that includes aqueous complexation, precipitation, ion exchange, and soil buffering reactions was developed and implemented in the code HydroGeoChem 5.0 (HGC5). Comparison of model results with experimental titration curves for contaminated groundwater alone and for soil- water systems indicated close agreement. This study is expected to facilitate field-scale modeling of geochemical processes under conditions with highly variable pH to develop practical methods to control contaminant mobility at geochemically complex sites.

  7. Using Contaminant Transport Modeling to Determine Historical Discharges at the Surface

    Science.gov (United States)

    Fogwell, T. W.

    2013-12-01

    When it is determined that a contaminated site needs to be remediated, the issue of who is going to pay for that remediation is an immediate concern. This means that there needs to be a determination of who the responsible parties are for the existing contamination. Seldom is it the case that records have been made and kept of the surface contaminant discharges. In many cases it is possible to determine the relative amount of contaminant discharge at the surface of the various responsible parties by employing a careful analysis of the history of contaminant transport through the surface, through the vadose zone, and within the saturated zone. The process begins with the development of a dynamic conceptual site model that takes into account the important features of the transport of the contaminants through the vadose zone and in the groundwater. The parameters for this model can be derived from flow data available for the site. The resulting contaminant transport model is a composite of the vadose zone transport model, together with the saturated zone (groundwater) flow model. Any calibration of the model should be carefully employed in order to avoid using information about the conclusions of the relative discharge amounts of the responsible parties in determining the calibrated parameters. Determination of the leading edge of the plume is an important first step. It is associated with the first discharges from the surface of the site. If there were several discharging parties at the same time, then it is important to establish a chemical or isotopic signature of the chemicals that were discharged. The time duration of the first discharger needs to be determined as accurately as possible in order to establish the appropriate characterization of the leading portion of the resulting plume in the groundwater. The information about the first discharger and the resulting part of the plume associated with this discharger serves as a basis for the determination of the

  8. Modeling hydrology and reactive transport in roads: The effect of cracks, the edge, and contaminant properties

    International Nuclear Information System (INIS)

    Apul, Defne S.; Gardner, Kevin H.; Eighmy, T. Taylor

    2007-01-01

    The goal of this research was to provide a tool for regulators to evaluate the groundwater contamination from the use of virgin and secondary materials in road construction. A finite element model, HYDRUS2D, was used to evaluate generic scenarios for secondary material use in base layers. Use of generic model results for particular applications was demonstrated through a steel slag example. The hydrology and reactive transport of contaminants were modeled in a two-dimensional cross section of a road. Model simulations showed that in an intact pavement, lateral velocities from the edge towards the centerline may transport contaminants in the base layer. The dominant transport mechanisms are advection closer to the edge and diffusion closer to the centerline. A shoulder joint in the pavement allows 0.03 to 0.45 m 3 /day of infiltration per meter of joint length as a function of the base and subgrade hydrology and the rain intensity. Scenario simulations showed that salts in the base layer of pavements are depleted by 99% in the first 20 years, whereas the metals may not reach the groundwater in 20 years at any significant concentrations if the pavement is built on adsorbing soils

  9. Impact of contamination with long-lived radionuclides on PET kinetics modelling in multitracer studies

    DEFF Research Database (Denmark)

    Jødal, Lars; Hansen, Søren Baarsgaard; Jensen, Svend B

    2016-01-01

    Introduction: An important issue in multitracer studies is the separation of signals from the different radiotracers. This is especially the case when an early tracer has a long physical half-life and kinetic modelling has to be performed, because the early tracer can confer a long-lived contamin......Introduction: An important issue in multitracer studies is the separation of signals from the different radiotracers. This is especially the case when an early tracer has a long physical half-life and kinetic modelling has to be performed, because the early tracer can confer a long...... of subsequent PET tracers. Blood sample counts were corrected by recounting the samples a few days later. A more optimal choice of energy window was also explored. The effect of correction versus noncorrection was investigated using a two-tissue kinetic model with irreversible uptake (K1, k2, k3). Results: K1...... counting of blood samples can lead to a contaminating background not observed in PET imaging and this background can affect kinetic modelling. If the contaminating tracer has a much longer half-life than the foreground tracer, then the problem can be solved by late recounting of the samples....

  10. Approach to uncertainty assessment for fluid flow and contaminant transport modeling in heterogeneous groundwater systems

    International Nuclear Information System (INIS)

    Nelson, R.W.; Jacobson, E.A.; Conbere, W.

    1985-06-01

    There is a growing awareness of the need to quantify uncertainty in groundwater flow and transport model results. Regulatory organizations are beginning to request the statistical distributions of predicted contaminant arrival to the biosphere, so that realistic confidence intervals can be obtained for the modeling results. To meet these needs, methods are being developed to quantify uncertainty in the subsurface flow and transport analysis sequence. A method for evaluating this uncertainty, described in this paper, considers uncertainty in material properties and was applied to an example field problem. Our analysis begins by using field measurements of transmissivity and hydraulic head in a regional, parameter estimation method to obtain a calibrated fluid flow model and a covariance matrix of the parameter estimation errors. The calibrated model and the covariance matrix are next used in a conditional simulation mode to generate a large number of 'head realizations.' The specific pore water velocity distribution for each realization is calculated from the effective porosity, the aquifer parameter realization, and the associated head values. Each velocity distribution is used to obtain a transport solution for a contaminant originating from the same source for all realizations. The results are the statistical distributions for the outflow arrival times. The confidence intervals for contamination reaching the biosphere are obtained from the outflow statistical distributions. 20 refs., 12 figs

  11. Model testing for the remediation assessment of a radium contaminated site in Olen, Belgium

    International Nuclear Information System (INIS)

    Sweeck, Lieve; Kanyar, Bela; Krajewski, Pawel; Kryshev, Alexander; Lietava, Peter; Nenyei, Arpad; Sazykina, Tatiana; Yu, Charley; Zeevaert, Theo

    2005-01-01

    Environmental assessment models are used as decision-aiding tools in the selection of remediation options for radioactively contaminated sites. In most cases, the effectiveness of the remedial actions in terms of dose savings cannot be demonstrated directly, but can be established with the help of environmental assessment models, through the assessment of future radiological impacts. It should be emphasized that, given the complexity of the processes involved and our current understanding of how they operate, these models are simplified descriptions of the behaviour of radionuclides in the environment and therefore imperfect. One way of testing and improving the reliability of the models is to compare their predictions with real data and/or the predictions of other models. Within the framework of the Remediation Assessment Working Group (RAWG) of the BIOMASS (BIOsphere Modelling and ASSessment) programme coordinated by IAEA, two scenarios were constructed and applied to test the reliability of environmental assessment models when remedial actions are involved. As a test site, an area of approximately 100 ha contaminated by the discharges of an old radium extraction plant in Olen (Belgium) has been considered. In the first scenario, a real situation was evaluated and model predictions were compared with measured data. In the second scenario the model predictions for specific hypothetical but realistic situations were compared. Most of the biosphere models were not developed to assess the performance of remedial actions and had to be modified for this purpose. It was demonstrated clearly that the modeller's experience and familiarity with the mathematical model, the site and with the scenario play a very important role in the outcome of the model calculations. More model testing studies, preferably for real situations, are needed in order to improve the models and modelling methods and to expand the areas in which the models are applicable

  12. Three-dimensional modeling, estimation, and fault diagnosis of spacecraft air contaminants.

    Science.gov (United States)

    Narayan, A P; Ramirez, W F

    1998-01-01

    A description is given of the design and implementation of a method to track the presence of air contaminants aboard a spacecraft using an accurate physical model and of a procedure that would raise alarms when certain tolerance levels are exceeded. Because our objective is to monitor the contaminants in real time, we make use of a state estimation procedure that filters measurements from a sensor system and arrives at an optimal estimate of the state of the system. The model essentially consists of a convection-diffusion equation in three dimensions, solved implicitly using the principle of operator splitting, and uses a flowfield obtained by the solution of the Navier-Stokes equations for the cabin geometry, assuming steady-state conditions. A novel implicit Kalman filter has been used for fault detection, a procedure that is an efficient way to track the state of the system and that uses the sparse nature of the state transition matrices.

  13. A Bayesian belief network approach for assessing uncertainty in conceptual site models at contaminated sites

    DEFF Research Database (Denmark)

    Thomsen, Nanna Isbak; Binning, Philip John; McKnight, Ursula S.

    2016-01-01

    the most important site-specific features and processes that may affect the contaminant transport behavior at the site. However, the development of a CSM will always be associated with uncertainties due to limited data and lack of understanding of the site conditions. CSM uncertainty is often found...... to be a major source of model error and it should therefore be accounted for when evaluating uncertainties in risk assessments. We present a Bayesian belief network (BBN) approach for constructing CSMs and assessing their uncertainty at contaminated sites. BBNs are graphical probabilistic models...... that are effective for integrating quantitative and qualitative information, and thus can strengthen decisions when empirical data are lacking. The proposed BBN approach facilitates a systematic construction of multiple CSMs, and then determines the belief in each CSM using a variety of data types and/or expert...

  14. Ground water contamination analysis by using a fully coupled numerical model

    International Nuclear Information System (INIS)

    Yahya Sukirman; Norhan Abd Rahman; Raihan Ismail

    1999-01-01

    Groundwater contamination in the subsurface is not a new or emerging issue, which can be highly toxic at very low concentrations. It can cause a great damage to our environment and public health. In recent years, accidental oil spill, leaking from underground storage and pipeline are getting more and more attention from various parties. There are very important to improve the understanding of the mobilization, transport mechanism and fate of hydrocarbon in the subsurface in checking the risk of public exposure to the contaminants and in evaluating various remediation scenarios. In this paper, groundwater contamination by nonaqueous phase liquids (NAPLs), such as organic solvents and petroleum hydrocarbons, will be simulated for a multiphase flow, heat flow and pollutant transport phenomenon in a semisaturated porous medium. The governing partial differential equations, in terms of soil displacements, fluid pressures, energy balance and concentrations are coupled and behave non-linearly but can be solved by a numerical method. Finally, the developed finite element model has been applied to analyze the transport behavior of hydrocarbon pollutant in subsurface, which can be used to propose a suitable remedial scheme for the groundwater contamination problems. (Author)

  15. A Generalized Model for Transport of Contaminants in Soil by Electric Fields

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Baek, Kitae; Alshawabkeh, Iyad D.

    2012-01-01

    with geochemical reactions such as aqueous equilibrium, sorption, precipitation and dissolution. The enhanced model is used to simulate electrokinetic cleanup of lead and copper contaminants at an Army Firing Range. Acid enhancement is achieved by the use of adipic acid to neutralize the basic front produced...... for the cathode electrochemical reaction. The model is able to simulate enhanced application of the process by modifying the boundary conditions. The model showed that kinetics of geochemical reactions, such as metals dissolution/leaching and redox reactions might be significant for realistic prediction...... of enhanced electrokinetic extraction of metals in real world applications....

  16. BETR Global - A geographically explicit global-scale multimedia contaminant fate model

    Energy Technology Data Exchange (ETDEWEB)

    Macleod, M.; Waldow, H. von; Tay, P.; Armitage, J. M.; Wohrnschimmel, H.; Riley, W.; McKone, T. E.; Hungerbuhler, K.

    2011-04-01

    We present two new software implementations of the BETR Global multimedia contaminant fate model. The model uses steady-state or non-steady-state mass-balance calculations to describe the fate and transport of persistent organic pollutants using a desktop computer. The global environment is described using a database of long-term average monthly conditions on a 15{sup o} x 15{sup o} grid. We demonstrate BETR Global by modeling the global sources, transport, and removal of decamethylcyclopentasiloxane (D5).

  17. Elements of a unified prognostic model for secondary air contamination by resuspension

    International Nuclear Information System (INIS)

    Besnus, F.; Garger, E.; Gordeev, S.; Hollaender, W.; Kashparov, V.; Martinez-Serrano, J.; Mironov, V.; Nicholson, K.; Tschiersch, J.; Vintersved, I.

    1996-01-01

    Based on results of several joint experimental campaigns and an extensive literature survey, a prognostic model was constructed capable of predicting airborne activity concentrations and size distributions as well as soil surface activity concentrations as a function of time and meteorological conditions. Example scenario calculations show that agricultural practices are of lesser importance to secondary air contamination than dust storms immediately after primary deposition and forest fires

  18. Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

    International Nuclear Information System (INIS)

    Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.

    2005-01-01

    CH2M HILL is producing risk/performance assessments to support the closure of single-shell tanks at the DOE's Hanford Site. As part of this effort, staff at PNNL were asked to develop release models for contaminants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. This report provides the information developed by PNNL

  19. Electrokinetic remediation of a copper contaminated soil - experiments and 1-D model

    Energy Technology Data Exchange (ETDEWEB)

    Vereda Alonso, C.; Hansen, H.K. [Inst. for Geologi and Geoteknik, Danmarks Tekniske Univ., Lyngby (Denmark); Gomez Lahoz, C.; Rodriguez Maroto, J.M. [Dept. de Ingenieria Quimica, Univ. de Malaga (Spain)

    2001-07-01

    In this work, a set of electrokinetic soil remediation experiments has been performed in a column containing a commercial standard kaolin that was previously contaminated with copper. The profile evolution of copper concentration and pH along the soil column was obtained from these experiments. A one-dimensional numerical model has been developed to simulate the experimental results obtained from these experiments. (orig.)

  20. Development and applications of two finite element groundwater flow and contaminant transport models: FEWA and FEMA

    International Nuclear Information System (INIS)

    Yeh, G.T.; Wong, K.V.; Craig, P.M.; Davis, E.C.

    1985-01-01

    This paper presents the construction, verification, and application of two groundwater flow and contaminant transport models: A Finite Element Model of Water Flow through Aquifers (FEWA) and A Finite Element Model of Material Transport through Aquifers (FEMA). The construction is based on the finite element approximation of partial differential equations of groundwater flow (FEWA) and of solute movement (FEMA). The particular features of FEWA and FEMA are their versatility and flexibility for dealing with nearly all vertically integrated two-dimensional problems. The models were verified against both analytical solutions and widely used US Geological Survey finite difference approximations. They were then applied for calibration and validation, using data obtained in experiments at the Engineering Test Facility at Oak Ridge National Laboratory. Results indicated that the models are valid for this specific site. To demonstrate the versatility anf flexibility of the models, they were applied to two hypothetical, but realistic, complex problems and three field sites across the United States. In these applications the models yielded good agreement with the field data for all three sites. Finally, the predictive capabilities of the models were demonstrated using data obtained at the Hialeah Preston site in Florida. This case illustrates the capability of FEWA and FEMA as predictive tools and their usefulness in the management of groundwater flow and contaminant transport. 25 refs

  1. Mathematical modeling of heavy metals contamination from MSW landfill site in Khon Kaen, Thailand.

    Science.gov (United States)

    Tantemsapya, N; Naksakul, Y; Wirojanagud, W

    2011-01-01

    Kham Bon landfill site is one of many municipality waste disposal sites in Thailand which are in an unsanitary condition. The site has been receiving municipality wastes without separating hazardous waste since 1968. Heavy metals including, Pb, Cr and Cd are found in soil and groundwater around the site, posing a health risk to people living nearby. In this research, contamination transport modelling of Pb, Cr and Cd was simulated using MODFLOW for two periods, at the present (2010) and 20 years prediction (2030). Model results showed that heavy metals, especially Pb and Cr migrated toward the north-eastern and south-eastern direction. The 20 years prediction showed that, heavy metals tend to move from the top soil to the deeper aquifer. The migration would not exceed 500 m radius from the landfill centre in the next 20 years, which is considered to be a slow process. From the simulation model, it is recommended that a mitigation measure should be performed to reduce the risk from landfill contamination. Hazardous waste should be separated for proper management. Groundwater contamination in the aquifer should be closely monitored. Consumption of groundwater in a 500 m radius must be avoided. In addition, rehabilitation of the landfill site should be undertaken to prevent further mobilization of pollutants.

  2. Mass discharge estimation from contaminated sites: Multi-model solutions for assessment of conceptual uncertainty

    DEFF Research Database (Denmark)

    Thomsen, Nanna Isbak; Troldborg, Mads; McKnight, Ursula S.

    2012-01-01

    site. The different conceptual models consider different source characterizations and hydrogeological descriptions. The idea is to include a set of essentially different conceptual models where each model is believed to be realistic representation of the given site, based on the current level...... the appropriate management option. The uncertainty of mass discharge estimates depends greatly on the extent of the site characterization. A good approach for uncertainty estimation will be flexible with respect to the investigation level, and account for both parameter and conceptual model uncertainty. We...... propose a method for quantifying the uncertainty of dynamic mass discharge estimates from contaminant point sources on the local scale. The method considers both parameter and conceptual uncertainty through a multi-model approach. The multi-model approach evaluates multiple conceptual models for the same...

  3. Pavlovian disgust conditioning as a model for contamination-based OCD: Evidence from an analogue study.

    Science.gov (United States)

    Armstrong, Thomas; Olatunji, Bunmi O

    2017-06-01

    Pavlovian fear conditioning provides a model for anxiety-related disorders, including obsessive-compulsive disorder (OCD). However, disgust is the predominant emotional response to contamination, which is a common theme in OCD. The present study sought to identify disgust conditioning abnormalities that may underlie excessive contamination concerns relevant to OCD. Individuals high and low in contamination concern (HCC, n = 32; LCC, n = 30) completed an associative learning task in which one neutral face (conditioned stimulus; CS+) was followed by a disgusting image (unconditioned stimulus; US) and another neutral face (CS-) was unreinforced. Following this acquisition procedure, there was an extinction procedure in which both CSs were presented unreinforced. The groups did not show significant differences in discriminant responding to the CSs following acquisition. However, following extinction, the HCC group reported less reduction in their expectancy of the US following the CS+, and also reported greater disgust to the CS+, compared to the LCC group. Increased disgust to the CS+ following both acquisition and extinction was correlated with increased symptoms of contamination-based OCD and increased disgust sensitivity. Additionally, disgust sensitivity mediated group differences in disgust responding to the CS+ at acquisition and extinction. Also, failure to adjust US expectancy in response to extinction partially mediated group differences in disgust to the CS+ following extinction. Together, these findings suggest that excessive contamination concerns observed in OCD may be related to difficulty inhibiting acquired disgust, possibly due to elevated disgust sensitivity that characterizes the disorder. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Source-term development for a contaminant plume for use by multimedia risk assessment models

    International Nuclear Information System (INIS)

    Whelan, Gene; McDonald, John P.; Taira, Randal Y.; Gnanapragasam, Emmanuel K.; Yu, Charley; Lew, Christine S.; Mills, William B.

    1999-01-01

    Multimedia modelers from the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE) are collaborating to conduct a comprehensive and quantitative benchmarking analysis of four intermedia models: DOE's Multimedia Environmental Pollutant Assessment System (MEPAS), EPA's MMSOILS, EPA's PRESTO, and DOE's RESidual RADioactivity (RESRAD). These models represent typical analytically, semi-analytically, and empirically based tools that are utilized in human risk and endangerment assessments for use at installations containing radioactive and/or hazardous contaminants. Although the benchmarking exercise traditionally emphasizes the application and comparison of these models, the establishment of a Conceptual Site Model (CSM) should be viewed with equal importance. This paper reviews an approach for developing a CSM of an existing, real-world, Sr-90 plume at DOE's Hanford installation in Richland, Washington, for use in a multimedia-based benchmarking exercise bet ween MEPAS, MMSOILS, PRESTO, and RESRAD. In an unconventional move for analytically based modeling, the benchmarking exercise will begin with the plume as the source of contamination. The source and release mechanism are developed and described within the context of performing a preliminary risk assessment utilizing these analytical models. By beginning with the plume as the source term, this paper reviews a typical process and procedure an analyst would follow in developing a CSM for use in a preliminary assessment using this class of analytical tool

  5. Modelling of a large-scale urban contamination situation and remediation alternatives

    International Nuclear Information System (INIS)

    Thiessen, K.M.; Arkhipov, A.; Batandjieva, B.; Charnock, T.W.; Gaschak, S.; Golikov, V.; Hwang, W.T.; Tomas, J.; Zlobenko, B.

    2009-01-01

    The Urban Remediation Working Group of the International Atomic Energy Agency's EMRAS (Environmental Modelling for Radiation Safety) program was organized to address issues of remediation assessment modelling for urban areas contaminated with dispersed radionuclides. The present paper describes the first of two modelling exercises, which was based on Chernobyl fallout data in the town of Pripyat, Ukraine. Modelling endpoints for the exercise included radionuclide concentrations and external dose rates at specified locations, contributions to the dose rates from individual surfaces and radionuclides, and annual and cumulative external doses to specified reference individuals. Model predictions were performed for a 'no action' situation (with no remedial measures) and for selected countermeasures. The exercise provided a valuable opportunity to compare modelling approaches and parameter values, as well as to compare the predicted effectiveness of various countermeasures with respect to short-term and long-term reduction of predicted doses to people.

  6. A model to determine the radiological implications of non-fixed radioactive contamination on the surfaces of packages and conveyances

    International Nuclear Information System (INIS)

    Hughes, J.S.; Warner Jones, S.M.; Lizot, M.T.; Perrin, M.L.; Thierfeld, S.; Schroedl, E.; Schwarz, G.; Rawl, R.; Munakata, M.; Hirose, M.

    2004-01-01

    The surfaces of packages and conveyances used to transport radioactive materials can sometimes become contaminated with radioactive material. This usually occurs as a result of the transfer of radioactive material from areas in which these packages and conveyances are handled. This contamination may subsequently be transferred to transport equipment, workers and to areas accessible to the public. This can represent a significant radiation safety issue that requires careful management. The current regulatory limits for non-fixed contamination on packages and conveyances have been in use for over 40 years, and are based on a simple exposure model. However, the bases on which these limits were derived have been subject to changes, as a result of successive revisions of international recommendations. In recognition of this need for a review and analysis of the current contamination limits an IAEA Co-ordinated Research Project (CRP) on the ''Radiological Aspects of Package and Conveyance Non-Fixed Contamination'' was initiated to review the scientific basis for the current regulatory limits for surface contamination. The CRP was also to develop guidance material for evaluating the radiological significance of surface contamination to workers and the public in light of state-of-the-art research, technical developments and current transport practices. The specific objectives of the work undertaken within this multi-national CRP were, in accordance with the terms of reference: To ensure that appropriate models exist for all package types including consideration of the aspects pertinent for assessing and revising a surface contamination model for transport. To collect - where possible - contamination, operational and dosimetric data to ensure modelling consistency. To use models for assessing the limitations and optimisation of radiation doses incurred in transport operations, and to consider preventive methods for package and conveyance contamination

  7. Integrating Modeling and Monitoring to Provide Long-Term Control of Contaminants

    International Nuclear Information System (INIS)

    Fogwell, Th.

    2009-01-01

    An introduction is presented of the types of problems that exist for long-term control of radionuclides at DOE sites. A breakdown of the distributions at specific sites is given, together with the associated difficulties. A paradigm for remediation showing the integration of monitoring with modeling is presented. It is based on a feedback system that allows for the monitoring to act as principal sensors in a control system. Currently the establishment of a very prescriptive monitoring program fails to have a mechanism for improving models and improving control of the contaminants. The resulting system can be optimized to improve performance. Optimizing monitoring automatically entails linking the monitoring with modeling. If monitoring designs were required to be more efficient, thus requiring optimization, then the monitoring automatically becomes linked to modeling. Records of decision could be written to accommodate revisions in monitoring as better modeling evolves. The technical pieces of the required paradigm are already available; they just need to be implemented and applied to solve the long-term control of the contaminants. An integration of the various parts of the system is presented. Each part is described, and examples are given. References are given to other projects which bring together similar elements in systems for the control of contaminants. Trends are given for the development of the technical features of a robust system. Examples of monitoring methods for specific sites are given. The examples are used to illustrate how such a system would work. Examples of technology needs are presented. Finally, other examples of integrated modeling-monitoring approaches are presented. (authors)

  8. Physiologically-based toxicokinetic models help identifying the key factors affecting contaminant uptake during flood events

    Energy Technology Data Exchange (ETDEWEB)

    Brinkmann, Markus; Eichbaum, Kathrin [Department of Ecosystem Analysis, Institute for Environmental Research,ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Kammann, Ulrike [Thünen-Institute of Fisheries Ecology, Palmaille 9, 22767 Hamburg (Germany); Hudjetz, Sebastian [Department of Ecosystem Analysis, Institute for Environmental Research,ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Cofalla, Catrina [Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Buchinger, Sebastian; Reifferscheid, Georg [Federal Institute of Hydrology (BFG), Department G3: Biochemistry, Ecotoxicology, Am Mainzer Tor 1, 56068 Koblenz (Germany); Schüttrumpf, Holger [Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Preuss, Thomas [Department of Environmental Biology and Chemodynamics, Institute for Environmental Research,ABBt- Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); and others

    2014-07-01

    Highlights: • A PBTK model for trout was coupled with a sediment equilibrium partitioning model. • The influence of physical exercise on pollutant uptake was studies using the model. • Physical exercise during flood events can increase the level of biliary metabolites. • Cardiac output and effective respiratory volume were identified as relevant factors. • These confounding factors need to be considered also for bioconcentration studies. - Abstract: As a consequence of global climate change, we will be likely facing an increasing frequency and intensity of flood events. Thus, the ecotoxicological relevance of sediment re-suspension is of growing concern. It is vital to understand contaminant uptake from suspended sediments and relate it to effects in aquatic biota. Here we report on a computational study that utilizes a physiologically based toxicokinetic model to predict uptake, metabolism and excretion of sediment-borne pyrene in rainbow trout (Oncorhynchus mykiss). To this end, data from two experimental studies were compared with the model predictions: (a) batch re-suspension experiments with constant concentration of suspended particulate matter at two different temperatures (12 and 24 °C), and (b) simulated flood events in an annular flume. The model predicted both the final concentrations and the kinetics of 1-hydroxypyrene secretion into the gall bladder of exposed rainbow trout well. We were able to show that exhaustive exercise during exposure in simulated flood events can lead to increased levels of biliary metabolites and identified cardiac output and effective respiratory volume as the two most important factors for contaminant uptake. The results of our study clearly demonstrate the relevance and the necessity to investigate uptake of contaminants from suspended sediments under realistic exposure scenarios.

  9. Physiologically-based toxicokinetic models help identifying the key factors affecting contaminant uptake during flood events

    International Nuclear Information System (INIS)

    Brinkmann, Markus; Eichbaum, Kathrin; Kammann, Ulrike; Hudjetz, Sebastian; Cofalla, Catrina; Buchinger, Sebastian; Reifferscheid, Georg; Schüttrumpf, Holger; Preuss, Thomas

    2014-01-01

    Highlights: • A PBTK model for trout was coupled with a sediment equilibrium partitioning model. • The influence of physical exercise on pollutant uptake was studies using the model. • Physical exercise during flood events can increase the level of biliary metabolites. • Cardiac output and effective respiratory volume were identified as relevant factors. • These confounding factors need to be considered also for bioconcentration studies. - Abstract: As a consequence of global climate change, we will be likely facing an increasing frequency and intensity of flood events. Thus, the ecotoxicological relevance of sediment re-suspension is of growing concern. It is vital to understand contaminant uptake from suspended sediments and relate it to effects in aquatic biota. Here we report on a computational study that utilizes a physiologically based toxicokinetic model to predict uptake, metabolism and excretion of sediment-borne pyrene in rainbow trout (Oncorhynchus mykiss). To this end, data from two experimental studies were compared with the model predictions: (a) batch re-suspension experiments with constant concentration of suspended particulate matter at two different temperatures (12 and 24 °C), and (b) simulated flood events in an annular flume. The model predicted both the final concentrations and the kinetics of 1-hydroxypyrene secretion into the gall bladder of exposed rainbow trout well. We were able to show that exhaustive exercise during exposure in simulated flood events can lead to increased levels of biliary metabolites and identified cardiac output and effective respiratory volume as the two most important factors for contaminant uptake. The results of our study clearly demonstrate the relevance and the necessity to investigate uptake of contaminants from suspended sediments under realistic exposure scenarios

  10. Remediation of a historically Pb contaminated soil using a model natural Mn oxide waste.

    Science.gov (United States)

    McCann, Clare M; Gray, Neil D; Tourney, Janette; Davenport, Russell J; Wade, Matthew; Finlay, Nina; Hudson-Edwards, Karen A; Johnson, Karen L

    2015-11-01

    A natural Mn oxide (NMO) waste was assessed as an in situ remediation amendment for Pb contaminated sites. The viability of this was investigated using a 10 month lysimeter trial, wherein a historically Pb contaminated soil was amended with a 10% by weight model NMO. The model NMO was found to have a large Pb adsorption capacity (qmax 346±14 mg g(-1)). However, due to the heterogeneous nature of the Pb contamination in the soils (3650.54-9299.79 mg kg(-1)), no treatment related difference in Pb via geochemistry could be detected. To overcome difficulties in traditional geochemical techniques due to pollutant heterogeneity we present a new method for unequivocally proving metal sorption to in situ remediation amendments. The method combines two spectroscopic techniques; namely electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS). Using this we showed Pb immobilisation on NMO, which were Pb free prior to their addition to the soils. Amendment of the soil with exogenous Mn oxide had no effect on microbial functioning, nor did it perturb the composition of the dominant phyla. We conclude that NMOs show excellent potential as remediation amendments. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. A statistical model for deriving probability distributions of contamination for accidental releases

    International Nuclear Information System (INIS)

    ApSimon, H.M.; Davison, A.C.

    1986-01-01

    Results generated from a detailed long-range transport model, MESOS, simulating dispersal of a large number of hypothetical releases of radionuclides in a variety of meteorological situations over Western Europe have been used to derive a simpler statistical model, MESOSTAT. This model may be used to generate probability distributions of different levels of contamination at a receptor point 100-1000 km or so from the source (for example, across a frontier in another country) without considering individual release and dispersal scenarios. The model is embodied in a series of equations involving parameters which are determined from such factors as distance between source and receptor, nuclide decay and deposition characteristics, release duration, and geostrophic windrose at the source. Suitable geostrophic windrose data have been derived for source locations covering Western Europe. Special attention has been paid to the relatively improbable extreme values of contamination at the top end of the distribution. The MESOSTAT model and its development are described, with illustrations of its use and comparison with the original more detailed modelling techniques. (author)

  12. Modeling Adsorption Kinetics (Bio-remediation of Heavy Metal Contaminated Water)

    Science.gov (United States)

    McCarthy, Chris

    My talk will focus on modeling the kinetics of the adsorption and filtering process using differential equations, stochastic methods, and recursive functions. The models have been developed in support of our interdisciplinary lab group which is conducting research into bio-remediation of heavy metal contaminated water via filtration through biomass such as spent tea leaves. The spent tea leaves are available in large quantities as a result of the industrial production of tea beverages. The heavy metals bond with the surfaces of the tea leaves (adsorption). Funding: CUNY Collaborative Incentive Research Grant.

  13. PARATI - a dynamic model for radiological assessments in urban areas. Pt. 1. Modelling of urban areas, their contamination and radiation fields

    International Nuclear Information System (INIS)

    Rochedo, E.R.R.; Conti, L.F.C.; Paretzke, H.G.

    1996-01-01

    The structure and mathematical model of PARATI, a detailed computer programme developed for the assessment of the radiological consequences of an accidental contamination of urban areas, is described with respect to the scenarios used for the estimation of exposure fields in a village or town, the models for the initial and secondary contamination with the radionuclide 137 Cs, the concepts for calculating the resulting radiation exposures and the changes with time of the contamination and radiation fields. Kerma rates at various locations in tropical urban areas are given, and the contribution of different contaminated surfaces to these rates after dry or wet deposition are discussed. (orig.). With 6 figs., 12 tabs

  14. Modeling Adsorption Based Filters (Bio-remediation of Heavy Metal Contaminated Water)

    Science.gov (United States)

    McCarthy, Chris

    I will discuss kinetic models of adsorption, as well as models of filters based on those mechanisms. These mathematical models have been developed in support of our interdisciplinary lab group, which is centered at BMCC/CUNY (City University of New York). Our group conducts research into bio-remediation of heavy metal contaminated water via filtration. The filters are constructed out of biomass, such as spent tea leaves. The spent tea leaves are available in large quantities as a result of the industrial production of tea beverages. The heavy metals bond with the surfaces of the tea leaves (adsorption). The models involve differential equations, stochastic methods, and recursive functions. I will compare the models' predictions to data obtained from computer simulations and experimentally by our lab group. Funding: CUNY Collaborative Incentive Research Grant (Round 12); CUNY Research Scholars Program.

  15. Multidimensional models for contaminants dispersion in rivers and channels: hybrid solutions via integral transforms

    International Nuclear Information System (INIS)

    Barros, Felipe Pereira Jorge de

    2004-05-01

    The aims of the present work were to use the Generalized Integral Transform Technique (GITT) to solve steady state multidimensional models for contaminants dispersion in rivers and channels, as well as to analyze the reduction of computational costs associated with convection-diffusion models that contains more than one space variable. The main focus of this work is the development of models that include variable coefficients such as variable velocity fields along and across the channel. The mathematical formulations also allow the use of different inlet conditions such as point sources, linear sources and plane sources. Several test cases were simulated and the models were validated numerically and with experimental data taken from the literature. The models were implemented in the symbolic computation platform, Mathematica 4.2. (author)

  16. Application of HEC-RAS water quality model to estimate contaminant spreading in small stream

    Energy Technology Data Exchange (ETDEWEB)

    Halaj, Peter; Bárek, Viliam; Halajová, Anna Báreková; Halajová, Denisa [Slovak University of Agriculture in Nitra, Nitra (Slovakia)

    2013-07-01

    The paper presents study of some aspects of HEC-RAS water quality model connected to simulation of contaminant transport in small stream. Authors mainly focused on one of the key tasks in process of pollutant transport modelling in streams - determination of the dispersion characteristics represented by longitudinal dispersion coefficient D. Different theoretical and empirical formulas have been proposed for D value determination and they have revealed that the coefficient is variable parameter that depends on hydraulic and morphometric characteristics of the stream reaches. Authors compare the results of several methods of coefficient D assessment, assuming experimental data obtained by tracer studies and compare them with results optimized by HEC-RAS water quality model. The analyses of tracer study and computation outputs allow us to outline the important aspects of longitudinal dispersion coefficient set up in process of the HEC-RAS model use. Key words: longitudinal dispersion coefficient, HEC-RAS, water quality modeling.

  17. Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

    Directory of Open Access Journals (Sweden)

    Anđelković Darko H.

    2012-01-01

    Full Text Available Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III and chromium(VI were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values.

  18. A feasibility study for decision-making support of a radioactive contamination model in an urban environment (METRO-K)

    International Nuclear Information System (INIS)

    Hwang, Won Tae; Han, Moon Hee; Jeong, Hyo Joon; Kim, Eun Han; Lee, Chang Woo

    2008-01-01

    A Korean urban contamination model METRO-K (Model for Estimates the Transient behavior of RadiOactive materials in the Korean urban environment), which is capable of calculating the exposure doses resulting from radioactive contamination in an urban environment, is taking part in a model testing program EMRAS (Environmental Modelling for RAdiation Safety) organized by the IAEA (International Atomic Energy Agency). For radioactive contamination scenarios of Pripyat districts and a hypothetical RDD (Radiological Dispersal Device), the predicted results using METRO-K were submitted to the EMRAS's urban contamination working group. In this paper, the predicted results for the contamination scenarios of a pripyat district were shown in case of both without remediation measures and with ones. Comparing with the predicted results of the models that have taken part in EMRAS program, a feasibility for decision-making support of METRO-K was investigated. As a predicted result of METRO-K, to take immediately remediation measures following a radioactive contamination, if possible, might be one of the best ways to reduce exposure dose. It was found that the discrepancies of predicted results among the models are resulted from 1) modeling approaches and applied parameter values, 2) exposure pathways which are considered in models, 3) assumptions of assessor such as contamination surfaces which might affect to an exposure receptor and their sizes, 4) parameter values which are related with remediation measures applied through literature survey. It was identified that a Korean urban contamination model METRO-K is a useful tool for decision-making support through the participation of EMRAS program

  19. From conceptual model to remediation: bioavailability, a key to clean up heavy metal contaminated soils.

    Science.gov (United States)

    Petruzzelli, Gianniantonio; Pedron, Francesca; Pezzarossa, Beatrice

    2013-04-01

    Processes of metal bioavailability in the soil To know the bioavailability processes at site specific levels is essential to understand in detail the risks associated with pollution, and to support the decision-making process, i.e. description of the conceptual model and choice of clean up technologies. It is particularly important to assess how chemical, physical and biological processes in the soil affect the reactions leading to adsorption, precipitation or release of contaminants. The measurement of bioavailability One of the main difficulties in the practical application of the bioavailability concept in soil remediation is the lack of consensus on the method to be used to measure bioavailability. The best strategy is to apply a series of tests to assess bioavailability, since no applicable method is universally valid under all conditions. As an example, bioavailability tests for phytotechnology application should consider two distinct aspects: a physico-chemical driven solubilization process and a physiologically driven uptake process. Soil and plant characteristics strongly influence bioavailability. Bioavailability as a tool in remediation strategies Bioavailability can be used at all stages in remediation strategies: development of the conceptual model, evaluation of risk assessment, and selection of the best technology, considering different scenarios and including different environmental objectives. Two different strategies can be followed: the reduction and the increase of bioavailability. Procedures that reduce bioavailability aim to prevent the movement of pollutants from the soil to the living organisms, essentially by: i) removal of the labile phase of the contaminant, i.e. the fraction which is intrinsic to the processes of bioavailability (phytostabilization); ii) conversion of the labile fraction into a stable fraction (precipitation or adsorption); iii) increase of the resistance to mass transfer of the contaminants (inertization). Procedures

  20. Mirasol PRT system inactivation efficacy evaluated in platelet concentrates by bacteria-contamination model

    Directory of Open Access Journals (Sweden)

    Jocić Miodrag

    2011-01-01

    Full Text Available Background/Aim. Bacterial contamination of blood components, primarily platelet concentrates (PCs, has been identified as one of the most frequent infectious complications in transfusion practice. PC units have a high risk for bacterial growth/multiplication due to their storage at ambient temperature (20 ± 2°C. Consequences of blood contamination could be effectively prevented or reduced by pathogen inactivation systems. The aim of this study was to determine the Mirasol pathogen reduction technology (PRT system efficacy in PCs using an artificial bacteria-contamination model. Methods. According to the ABO blood groups, PC units (n = 216 were pooled into 54 pools (PC-Ps. PC-Ps were divided into three equal groups, with 18 units in each, designed for an artificial bacteria-contamination. Briefly, PC-Ps were contaminated by Staphylococcus epidermidis, Staphylococcus aureus or Escherichia coli in concentrations 102 to 107 colony forming units (CFU per unit. Afterward, PC-Ps were underwent to inactivation by Mirasol PRT system, using UV (l = 265-370 nm activated riboflavin (RB. All PC-Ps were assayed by BacT/Alert Microbial Detection System for CFU quantification before and after the Mirasol treatment. Samples from non-inactivated PC-P units were tested after preparation and immediately following bacterial contamination. Samples from Mirasol treated units were quantified for CFUs one hour, 3 days and 5 days after inactivation. Results. A complete inactivation of all bacteria species was obtained at CFU concentrations of 102 and 103 per PC-P unit through storage/ investigation period. The most effective inactivation (105 CFU per PC-P unit was obtained in Escherichia coli setting. Contrary, inactivation of all the three tested bacteria species was unworkable in concentrations of ≥ 106 CFU per PC-P unit. Conclusion. Efficient inactivation of investigated bacteria types with a significant CFU depletion in PC-P units was obtained - 3 Log for all

  1. The effect of a loss of model structural detail due to network skeletonization on contamination warning system design: case studies

    Science.gov (United States)

    Davis, Michael J.; Janke, Robert

    2018-05-01

    The effect of limitations in the structural detail available in a network model on contamination warning system (CWS) design was examined in case studies using the original and skeletonized network models for two water distribution systems (WDSs). The skeletonized models were used as proxies for incomplete network models. CWS designs were developed by optimizing sensor placements for worst-case and mean-case contamination events. Designs developed using the skeletonized network models were transplanted into the original network model for evaluation. CWS performance was defined as the number of people who ingest more than some quantity of a contaminant in tap water before the CWS detects the presence of contamination. Lack of structural detail in a network model can result in CWS designs that (1) provide considerably less protection against worst-case contamination events than that obtained when a more complete network model is available and (2) yield substantial underestimates of the consequences associated with a contamination event. Nevertheless, CWSs developed using skeletonized network models can provide useful reductions in consequences for contaminants whose effects are not localized near the injection location. Mean-case designs can yield worst-case performances similar to those for worst-case designs when there is uncertainty in the network model. Improvements in network models for WDSs have the potential to yield significant improvements in CWS designs as well as more realistic evaluations of those designs. Although such improvements would be expected to yield improved CWS performance, the expected improvements in CWS performance have not been quantified previously. The results presented here should be useful to those responsible for the design or implementation of CWSs, particularly managers and engineers in water utilities, and encourage the development of improved network models.

  2. Molecular-level removal of proteinaceous contamination from model surfaces and biomedical device materials by air plasma treatment.

    Science.gov (United States)

    Banerjee, K K; Kumar, S; Bremmell, K E; Griesser, H J

    2010-11-01

    Established methods for cleaning and sterilising biomedical devices may achieve removal of bioburden only at the macroscopic level while leaving behind molecular levels of contamination (mainly proteinaceous). This is of particular concern if the residue might contain prions. We investigated at the molecular level the removal of model and real-life proteinaceous contamination from model and practical surfaces by air plasma (ionised air) treatment. The surface-sensitive technique of X-ray photoelectron spectroscopy (XPS) was used to assess the removal of proteinaceous contamination, with the nitrogen (N1s) photoelectron signal as its marker. Model proteinaceous contamination (bovine serum albumin) adsorbed on to a model surface (silicon wafer) and the residual proteinaceous contamination resulting from incubating surgical stainless steel (a practical biomaterial) in whole human blood exhibited strong N1s signals [16.8 and 18.5 atomic percent (at.%), respectively] after thorough washing. After 5min air plasma treatment, XPS detected no nitrogen on the sample surfaces, indicating complete removal of proteinaceous contamination, down to the estimated XPS detection limit 10ng/cm(2). Applying the same plasma treatment, the 7.7at.% nitrogen observed on a clinically cleaned dental bur was reduced to a level reflective of new, as-received burs. Contact angle measurements and atomic force microscopy also indicated complete molecular-level removal of the proteinaceous contamination upon air plasma treatment. This study demonstrates the effectiveness of air plasma treatment for removing proteinaceous contamination from both model and practical surfaces and offers a method for ensuring that no molecular residual contamination such as prions is transferred upon re-use of surgical and dental instruments. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  3. Heterogeneity and contaminant transport modeling for the Savannah River integrated demonstration site

    International Nuclear Information System (INIS)

    Chesnut, D.A.

    1992-11-01

    The effectiveness of remediating aquifers and vadose zone sediments is frequently controlled by spatial heterogeneities. A continuing and long-recognized problem in selecting, planning, implementing, and operating remediation projects is the development of methods for quantitatively describing heterogeneity and predicting its effects on process performance. The similarity to and differences from modeling oil recovery processes in the petroleum industry are illustrated by the extension to contaminant extraction processes of an analytic model originally developed for waterflooding petroleum reservoirs. The resulting equations incorporate the effects of heterogeneity through a single parameter, σ. Fitting this model to the Savannah River in situ Air Stripping test data suggests that the injection of air into a horizontal well below the water table may have improved performance by changing the flow pattern in the vadose zone. This change increased the capture volume, and consequently the contaminant mass inventory, of the horizontal injection well completed in the vadose zone. The apparent increases (compared to extraction only from the horizontal well) are from 10,200 to 21,000 pounds for TCE and from 3,600 pounds to 59,800 pounds for PCE. The predominance of PCE in this calculated increase suggests that redistribution of flow paths in the vadose zone, rather than in-situ stripping, may provide most of the improvement. Although this preliminary conclusion remains to be reinforced by more sophisticated modeling currently in progress, there appears to be a definite improvement, which is attributable to air injection, over conventional remediation methods

  4. A generalized model for transport of contaminants in soil by electric fields.

    Science.gov (United States)

    Paz-Garcia, Juan Manuel; Baek, Kitae; Alshawabkeh, Iyad D; Alshawabkeh, Akram N

    2012-01-01

    A generalized model applicable to soils contaminated with multiple species under enhanced boundary conditions during treatment by electric fields is presented. The partial differential equations describing species transport are developed by applying the law of mass conservation to their fluxes. Transport, due to migration, advection and diffusion, of each aqueous component and complex species are combined to produce one partial differential equation that describes transport of the total analytical concentrations of component species which are the primary dependent variables. This transport couples with geochemical reactions such as aqueous equilibrium, sorption, precipitation and dissolution. The enhanced model is used to simulate electrokinetic cleanup of lead and copper contaminants at an Army Firing Range. Acid enhancement is achieved by the use of adipic acid to neutralize the basic front produced for the cathode electrochemical reaction. The model is able to simulate enhanced application of the process by modifying the boundary conditions. The model showed that kinetics of geochemical reactions, such as metals dissolution/leaching and redox reactions, may be significant for realistic prediction of enhanced electrokinetic extraction of metals in real-world applications.

  5. Modeled occupational exposures to gas-phase medical laser-generated air contaminants.

    Science.gov (United States)

    Lippert, Julia F; Lacey, Steven E; Jones, Rachael M

    2014-01-01

    Exposure monitoring data indicate the potential for substantive exposure to laser-generated air contaminants (LGAC); however the diversity of medical lasers and their applications limit generalization from direct workplace monitoring. Emission rates of seven previously reported gas-phase constituents of medical laser-generated air contaminants (LGAC) were determined experimentally and used in a semi-empirical two-zone model to estimate a range of plausible occupational exposures to health care staff. Single-source emission rates were generated in an emission chamber as a one-compartment mass balance model at steady-state. Clinical facility parameters such as room size and ventilation rate were based on standard ventilation and environmental conditions required for a laser surgical facility in compliance with regulatory agencies. All input variables in the model including point source emission rates were varied over an appropriate distribution in a Monte Carlo simulation to generate a range of time-weighted average (TWA) concentrations in the near and far field zones of the room in a conservative approach inclusive of all contributing factors to inform future predictive models. The concentrations were assessed for risk and the highest values were shown to be at least three orders of magnitude lower than the relevant occupational exposure limits (OELs). Estimated values do not appear to present a significant exposure hazard within the conditions of our emission rate estimates.

  6. A compositional multiphase model for groundwater contamination by petroleum products: 1. Theoretical considerations

    Science.gov (United States)

    Corapcioglu, M. Yavuz; Baehr, Arthur L.

    1987-01-01

    A mathematical model is developed to describe the fate of hydrocarbon constituents of petroleum products introduced to soils as an immiscible liquid from sources such as leaking underground storage tanks and ruptured pipelines. The problem is one of multiphase transport (oil (immiscible), air, and water phases) of a reactive contaminant with constituents such as benzene, toluene, and xylene found in refined petroleum products like gasoline. In the unsaturated zone, transport of each constituent can occur as a solute in the water phase, vapor in the air phase, and as an unaltered constituent in the oil phase. Additionally, the model allows for adsorption. Molecular transformations, microbially mediated or abiotic, are incorporated as sink terms in the conservation of mass equations. An equilibrium approximation, applicable to any immiscible organic contaminant is applied to partition constituent mass between the air, oil, water, and adsorbed phases for points in the region where the oil phase exists. Outside the oil plume the equilibrium approximation takes on a simpler form to partition constituent mass between the air, water, and adsorbed phases only. Microbial degradation of petroleum products is first discussed in a general model, then the conservation of mass equation for oxygen is incorporated into the analysis which takes advantage of the key role played by oxygen in the metabolism of hydrocarbon utilizing microbes in soil environments. Approximations to two subproblems, oil plume establishment in the unsaturated zone, and solute and vapor transport subsequent to immiscible plume establishment are then developed from the general model.

  7. Integrated modelling for assessing the risk of groundwater contaminants to human health and surface water ecosystems

    DEFF Research Database (Denmark)

    McKnight, Ursula S.; Rasmussen, Jes; Funder, Simon G.

    2010-01-01

    for evaluating the impact of a TCE groundwater plume, located in an area with protected drinking water interests, to human health and surface water ecosystems. This is accomplished by coupling the system dynamicsbased decision support system CARO-Plus to the aquatic ecosystem model AQUATOX via an analytical......The practical implementation of the European Water Framework Directive has resulted in an increased focus on the groundwater-surface water interaction zone. A gap exists with respect to preliminary assessment methodologies that are capable of evaluating and prioritising point sources...... volatilisation model for the stream. The model is tested on a Danish case study involving a 750 m long TCE groundwater plume discharging into a stream. The initial modelling results indicate that TCE contaminant plumes with μgL-1 concentrations entering surface water systems do not pose a significant risk...

  8. Accounting for pH heterogeneity and variability in modelling human health risks from cadmium in contaminated land

    International Nuclear Information System (INIS)

    Gay, J. Rebecca; Korre, Anna

    2009-01-01

    The authors have previously published a methodology which combines quantitative probabilistic human health risk assessment and spatial statistical methods (geostatistics) to produce an assessment, incorporating uncertainty, of risks to human health from exposure to contaminated land. The model assumes a constant soil to plant concentration factor (CF veg ) when calculating intake of contaminants. This model is modified here to enhance its use in a situation where CF veg varies according to soil pH, as is the case for cadmium. The original methodology uses sequential indicator simulation (SIS) to map soil concentration estimates for one contaminant across a site. A real, age-stratified population is mapped across the contaminated area, and intake of soil contaminants by individuals is calculated probabilistically using an adaptation of the Contaminated Land Exposure Assessment (CLEA) model. The proposed improvement involves not only the geostatistical estimation of the contaminant concentration, but also that of soil pH, which in turn leads to a variable CF veg estimate which influences the human intake results. The results presented demonstrate that taking pH into account can influence the outcome of the risk assessment greatly. It is proposed that a similar adaptation could be used for other combinations of soil variables which influence CF veg .

  9. Groundwater contamination from an inactive uranium mill tailings pile. 2. Application of a dynamic mixing model

    International Nuclear Information System (INIS)

    Narashimhan, T.N.; White, A.F.; Tokunaga, T.

    1986-01-01

    At Riverton, Wyoming, low pH process waters from an abandoned uranium mill tailings pile have been infiltrating into and contaminating the shallow water table aquifer. The contamination process has been governed by transient infiltration rates, saturated-unsaturated flow, as well as transient chemical reactions between the many chemical species present in the mixing waters and the sediments. In the first part of this two-part series the authors presented field data as well as an interpretation based on a static mixing models. As an upper bound, the authors estimated that 1.7% of the tailings water had mixed with the native groundwater. In the present work they present the results of numerical investigation of the dynamic mixing process. The model, DYNAMIX (DYNamic MIXing), couples a chemical speciation algorithm, PHREEQE, with a modified form of the transport algorithm, TRUMP, specifically designed to handle the simultaneous migration of several chemical constituents. The overall problem of simulating the evolution and migration of the contaminant plume was divided into three sub problems that were solved in sequential stages. These were the infiltration problem, the reactive mixing problem, and the plume-migration problem. The results of the application agree reasonably with the detailed field data. The methodology developed in the present study demonstrates the feasibility of analyzing the evolution of natural hydrogeochemical systems through a coupled analysis of transient fluid flow as well as chemical reactions. It seems worthwhile to devote further effort toward improving the physicochemical capabilities of the model as well as to enhance its computational efficiency

  10. An Iterative Ensemble Kalman Filter with One-Step-Ahead Smoothing for State-Parameters Estimation of Contaminant Transport Models

    KAUST Repository

    Gharamti, M. E.; Ait-El-Fquih, Boujemaa; Hoteit, Ibrahim

    2015-01-01

    Numerical experiments are conducted with a two-dimensional synthetic subsurface transport model simulating the migration of a contaminant plume in a heterogenous aquifer domain. Contaminant concentration data are assimilated to estimate both the contaminant state and the hydraulic conductivity field. Assimilation runs are performed under imperfect modeling conditions and various observational scenarios. Simulation results suggest that the proposed scheme efficiently recovers both the contaminant state and the aquifer conductivity, providing more accurate estimates than the standard Joint and Dual EnKFs in all tested scenarios. Iterating on the update step of the new scheme further enhances the proposed filter’s behavior. In term of computational cost, the new Joint-EnKF is almost equivalent to that of the Dual-EnKF, but requires twice more model integrations than the standard Joint-EnKF.

  11. A Stochastic Model to Assess the Effect of Meat Inspection Practices on the Contamination of the Pig Carcasses

    DEFF Research Database (Denmark)

    de Freitas Costa, Eduardo; Corbellini, Luis Gustavo; da Silva, Ana Paula Serafini Poeta

    2017-01-01

    The objective of meat inspection is to promote animal and public health by preventing, detecting, and controlling hazards originating from animals. With the improvements of sanitary level in pig herds, the hazards profile has shifted and the inspection procedures no longer target major foodborne...... pathogens (i.e., not risk based). Additionally, carcass manipulations performed when searching for macroscopic lesions can lead to cross-contamination. We therefore developed a stochastic model to quantitatively describe cross-contamination when consecutive carcasses are submitted to classic inspection...... procedures. The microbial hazard used to illustrate the model was Salmonella, the data set was obtained from Brazilian slaughterhouses, and some simplifying assumptions were made. The model predicted that due to cross-contamination during inspection, the prevalence of contaminated carcass surfaces increased...

  12. Contaminant transport at a waste residue deposit: 1. Inverse flow and non-reactive transport modelling

    DEFF Research Database (Denmark)

    Sonnenborg, Torben Obel; Engesgaard, Peter Knudegaard; Rosbjerg, Dan

    1996-01-01

    An application of an inverse flow and transport model to a contaminated aquifer is presented. The objective of the study is to identify physical and nonreactive flow and transport parameters through an optimization approach. The approach can be classified as a statistical procedure, where a flow...... to steady state versus transient flow conditions and to the amount of hydraulic and solute data used is investigated. The flow parameters, transmissivity and leakage factor, are estimated simultaneously with the transport parameters: source strength, porosity, and longitudinal dispersivity. This paper...

  13. Identifying optimal agricultural countermeasure strategies for a hypothetical contamination scenario using the strategy model

    International Nuclear Information System (INIS)

    Cox, G.; Beresford, N.A.; Alvarez-Farizo, B.; Oughton, D.; Kis, Z.; Eged, K.; Thorring, H.; Hunt, J.; Wright, S.; Barnett, C.L.; Gil, J.M.; Howard, B.J.; Crout, N.M.J.

    2005-01-01

    A spatially implemented model designed to assist the identification of optimal countermeasure strategies for radioactively contaminated regions is described. Collective and individual ingestion doses for people within the affected area are estimated together with collective exported ingestion dose. A range of countermeasures are incorporated within the model, and environmental restrictions have been included as appropriate. The model evaluates the effectiveness of a given combination of countermeasures through a cost function which balances the benefit obtained through the reduction in dose with the cost of implementation. The optimal countermeasure strategy is the combination of individual countermeasures (and when and where they are implemented) which gives the lowest value of the cost function. The model outputs should not be considered as definitive solutions, rather as interactive inputs to the decision making process. As a demonstration the model has been applied to a hypothetical scenario in Cumbria (UK). This scenario considered a published nuclear power plant accident scenario with a total deposition of 1.7 x 10 14 , 1.2 x 10 13 , 2.8 x 10 10 and 5.3 x 10 9 Bq for Cs-137, Sr-90, Pu-239/240 and Am-241, respectively. The model predicts that if no remediation measures were implemented the resulting collective dose would be approximately 36 000 person-Sv (predominantly from 137 Cs) over a 10-year period post-deposition. The optimal countermeasure strategy is predicted to avert approximately 33 000 person-Sv at a cost of approximately pound 160 million. The optimal strategy comprises a mixture of ploughing, AFCF (ammonium-ferric hexacyano-ferrate) administration, potassium fertiliser application, clean feeding of livestock and food restrictions. The model recommends specific areas within the contaminated area and time periods where these measures should be implemented

  14. Modelling phytoremediation by the hyperaccumulating fern, Pteris vittata, of soils historically contaminated with arsenic

    International Nuclear Information System (INIS)

    Shelmerdine, Paula A.; Black, Colin R.; McGrath, Steve P.; Young, Scott D.

    2009-01-01

    Pteris vittata plants were grown on twenty-one UK soils contaminated with arsenic (As) from a wide range of natural and anthropogenic sources. Arsenic concentration was measured in fern fronds, soil and soil pore water collected with Rhizon samplers. Isotopically exchangeable soil arsenate was determined by equilibration with 73 As V . Removal of As from the 21 soils by three sequential crops of P. vittata ranged between 0.1 and 13% of total soil As. Ferns grown on a soil subjected to long-term sewage sludge application showed reduced uptake of As because of high available phosphate concentrations. A combined solubility-uptake model was parameterised to enable prediction of phytoremediation success from estimates of soil As, 'As-lability' and soil pH. The model was used to demonstrate the remediation potential of P. vittata under different soil conditions and with contrasting assumptions regarding re-supply of the labile As pool from unavailable forms. - This paper presents a predictive model for phytoremediation of soils, historically contaminated with arsenic, by the hyperaccumulator P. vittata.

  15. Modelling phytoremediation by the hyperaccumulating fern, Pteris vittata, of soils historically contaminated with arsenic

    Energy Technology Data Exchange (ETDEWEB)

    Shelmerdine, Paula A.; Black, Colin R. [School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD (United Kingdom); McGrath, Steve P. [Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom); Young, Scott D., E-mail: scott.young@nottingham.ac.u [School of Biosciences, Biology Building, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2009-05-15

    Pteris vittata plants were grown on twenty-one UK soils contaminated with arsenic (As) from a wide range of natural and anthropogenic sources. Arsenic concentration was measured in fern fronds, soil and soil pore water collected with Rhizon samplers. Isotopically exchangeable soil arsenate was determined by equilibration with {sup 73}As{sup V}. Removal of As from the 21 soils by three sequential crops of P. vittata ranged between 0.1 and 13% of total soil As. Ferns grown on a soil subjected to long-term sewage sludge application showed reduced uptake of As because of high available phosphate concentrations. A combined solubility-uptake model was parameterised to enable prediction of phytoremediation success from estimates of soil As, 'As-lability' and soil pH. The model was used to demonstrate the remediation potential of P. vittata under different soil conditions and with contrasting assumptions regarding re-supply of the labile As pool from unavailable forms. - This paper presents a predictive model for phytoremediation of soils, historically contaminated with arsenic, by the hyperaccumulator P. vittata.

  16. Assessing clustering strategies for Gaussian mixture filtering a subsurface contaminant model

    KAUST Repository

    Liu, Bo

    2016-02-03

    An ensemble-based Gaussian mixture (GM) filtering framework is studied in this paper in term of its dependence on the choice of the clustering method to construct the GM. In this approach, a number of particles sampled from the posterior distribution are first integrated forward with the dynamical model for forecasting. A GM representation of the forecast distribution is then constructed from the forecast particles. Once an observation becomes available, the forecast GM is updated according to Bayes’ rule. This leads to (i) a Kalman filter-like update of the particles, and (ii) a Particle filter-like update of their weights, generalizing the ensemble Kalman filter update to non-Gaussian distributions. We focus on investigating the impact of the clustering strategy on the behavior of the filter. Three different clustering methods for constructing the prior GM are considered: (i) a standard kernel density estimation, (ii) clustering with a specified mixture component size, and (iii) adaptive clustering (with a variable GM size). Numerical experiments are performed using a two-dimensional reactive contaminant transport model in which the contaminant concentration and the heterogenous hydraulic conductivity fields are estimated within a confined aquifer using solute concentration data. The experimental results suggest that the performance of the GM filter is sensitive to the choice of the GM model. In particular, increasing the size of the GM does not necessarily result in improved performances. In this respect, the best results are obtained with the proposed adaptive clustering scheme.

  17. CERES: a model of forest stand biomass dynamics for predicting trace contaminant, nutrient, and water effects. I. Model description

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, K R; Luxmoore, R J; Begovich, C L

    1978-06-01

    CERES is a forest stand growth model which incorporates sugar transport in order to predict both short-term effects and long-term accumulation of trace contaminants and/or nutrients when coupled with the soil chemistry model (SCHEM), and models of solute uptake (DIFMAS and DRYADS) of the Unified Transport Model, UTM. An important feature of CERES is its ability to interface with the soil--plant--atmosphere water model (PROSPER) as a means of both predicting and studying the effects of plant water status on growth and solute transport. CERES considers the biomass dynamics of plants, standing dead and litter with plants divided into leaves, stems, roots, and fruits. The plant parts are divided further into sugar substrate, storage, and in the case of stems and roots, heartwood components. Each ecosystem omponent is described by a mass balance equation written as a first-order ordinary differential equation.

  18. Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Denglong [Fuli School of Food Equipment Engineering and Science, Xi’an Jiaotong University, No.28 Xianning West Road, Xi’an 710049 (China); Zhang, Zaoxiao, E-mail: zhangzx@mail.xjtu.edu.cn [State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, No.28 Xianning West Road, Xi’an 710049 (China); School of Chemical Engineering and Technology, Xi’an Jiaotong University, No.28 Xianning West Road, Xi’an 710049 (China)

    2016-07-05

    Highlights: • The intelligent network models were built to predict contaminant gas concentrations. • The improved network models coupled with Gaussian dispersion model were presented. • New model has high efficiency and accuracy for concentration prediction. • New model were applied to indentify the leakage source with satisfied results. - Abstract: Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem.

  19. Contaminant dispersion prediction and source estimation with integrated Gaussian-machine learning network model for point source emission in atmosphere

    International Nuclear Information System (INIS)

    Ma, Denglong; Zhang, Zaoxiao

    2016-01-01

    Highlights: • The intelligent network models were built to predict contaminant gas concentrations. • The improved network models coupled with Gaussian dispersion model were presented. • New model has high efficiency and accuracy for concentration prediction. • New model were applied to indentify the leakage source with satisfied results. - Abstract: Gas dispersion model is important for predicting the gas concentrations when contaminant gas leakage occurs. Intelligent network models such as radial basis function (RBF), back propagation (BP) neural network and support vector machine (SVM) model can be used for gas dispersion prediction. However, the prediction results from these network models with too many inputs based on original monitoring parameters are not in good agreement with the experimental data. Then, a new series of machine learning algorithms (MLA) models combined classic Gaussian model with MLA algorithm has been presented. The prediction results from new models are improved greatly. Among these models, Gaussian-SVM model performs best and its computation time is close to that of classic Gaussian dispersion model. Finally, Gaussian-MLA models were applied to identifying the emission source parameters with the particle swarm optimization (PSO) method. The estimation performance of PSO with Gaussian-MLA is better than that with Gaussian, Lagrangian stochastic (LS) dispersion model and network models based on original monitoring parameters. Hence, the new prediction model based on Gaussian-MLA is potentially a good method to predict contaminant gas dispersion as well as a good forward model in emission source parameters identification problem.

  20. A model of accumulation of radionuclides in biosphere originating from groundwater contamination

    Energy Technology Data Exchange (ETDEWEB)

    Gaerdenaes, Annemieke [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Soil Sciences; Jansson, Per-Erik; Karlberg, Louise [Royal Inst. of Technology, Stockholm (Sweden). Dept. Land and Water Resources

    2006-03-15

    The objective of this study is to introduce a module in CoupModel describing the transport and accumulation in the biosphere of a radionuclide originating from a ground water contamination. Two model approaches describing the plant uptake of a radionuclide were included, namely passive and active uptake. Passive uptake means in this study that the root uptake rate of a radionuclide is governed by water uptake. Normal mechanism for the passive water uptake is the convective flux of water from the soil to the plant. An example of element taken up passively is Ca. Active plant uptake is in this model defined as the root uptake rate of a radionuclide that is governed by carbon assimilation i.e. photosynthesis and plant growth. The actively taken up element can for example be an element essential to plant, but not available in high enough concentration by passive uptake alone, like the major nutrients N and P or an element that very well resembles a plant nutrient, like Cs resembles K. Active uptake of trace element may occur alone or in addition to passive uptake. Normal mechanism for the active uptake is molecular diffusion from the soil solution to the roots or via any other organism living in symbiosis with the roots like the mycorrhiza. Also a model approach describing adsorption was introduced. CoupModel dynamically couples and simulates the flows of water, heat, carbon and nitrogen in the soil/plant/atmosphere system. Any number of plants may be defined and are divided into roots, leaves, stem and grain. The soil is considered in one vertical profile that may be represented into a maximum of 100 layers. The model is the windows-successor and integrated version of the DOS-models SOIL and SOILN, which have been widely used on different ecosystems and climate regions during 25 years time period. To this soil/plant/atmosphere model were introduced a module describing accumulation of a radionuclide in the biosphere originating from groundwater contamination. The

  1. A model of accumulation of radionuclides in biosphere originating from groundwater contamination

    International Nuclear Information System (INIS)

    Gaerdenaes, Annemieke; Jansson, Per-Erik; Karlberg, Louise

    2006-03-01

    The objective of this study is to introduce a module in CoupModel describing the transport and accumulation in the biosphere of a radionuclide originating from a ground water contamination. Two model approaches describing the plant uptake of a radionuclide were included, namely passive and active uptake. Passive uptake means in this study that the root uptake rate of a radionuclide is governed by water uptake. Normal mechanism for the passive water uptake is the convective flux of water from the soil to the plant. An example of element taken up passively is Ca. Active plant uptake is in this model defined as the root uptake rate of a radionuclide that is governed by carbon assimilation i.e. photosynthesis and plant growth. The actively taken up element can for example be an element essential to plant, but not available in high enough concentration by passive uptake alone, like the major nutrients N and P or an element that very well resembles a plant nutrient, like Cs resembles K. Active uptake of trace element may occur alone or in addition to passive uptake. Normal mechanism for the active uptake is molecular diffusion from the soil solution to the roots or via any other organism living in symbiosis with the roots like the mycorrhiza. Also a model approach describing adsorption was introduced. CoupModel dynamically couples and simulates the flows of water, heat, carbon and nitrogen in the soil/plant/atmosphere system. Any number of plants may be defined and are divided into roots, leaves, stem and grain. The soil is considered in one vertical profile that may be represented into a maximum of 100 layers. The model is the windows-successor and integrated version of the DOS-models SOIL and SOILN, which have been widely used on different ecosystems and climate regions during 25 years time period. To this soil/plant/atmosphere model were introduced a module describing accumulation of a radionuclide in the biosphere originating from groundwater contamination. The

  2. Illustrating sensitivity in environmental fate models using partitioning maps - application to selected contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, T.; Wania, F. [Univ. of Toronto at Scarborough - DPES, Toronto (Canada)

    2004-09-15

    Generic environmental multimedia fate models are important tools in the assessment of the impact of organic pollutants. Because of limited possibilities to evaluate generic models by comparison with measured data and the increasing regulatory use of such models, uncertainties of model input and output are of considerable concern. This led to a demand for sensitivity and uncertainty analyses for the outputs of environmental fate models. Usually, variations of model predictions of the environmental fate of organic contaminants are analyzed for only one or at most a few selected chemicals, even though parameter sensitivity and contribution to uncertainty are widely different for different chemicals. We recently presented a graphical method that allows for the comprehensive investigation of model sensitivity and uncertainty for all neutral organic chemicals simultaneously. This is achieved by defining a two-dimensional hypothetical ''chemical space'' as a function of the equilibrium partition coefficients between air, water, and octanol (K{sub OW}, K{sub AW}, K{sub OA}), and plotting sensitivity and/or uncertainty of a specific model result to each input parameter as function of this chemical space. Here we show how such sensitivity maps can be used to quickly identify the variables with the highest influence on the environmental fate of selected, chlorobenzenes, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs) and brominated flame retardents (BFRs).

  3. Developing an integrated 3D-hydrodynamic and emerging contaminant model for assessing water quality in a Yangtze Estuary Reservoir.

    Science.gov (United States)

    Xu, Cong; Zhang, Jingjie; Bi, Xiaowei; Xu, Zheng; He, Yiliang; Gin, Karina Yew-Hoong

    2017-12-01

    An integrated 3D-hydrodynamic and emerging contaminant model was developed for better understanding of the fate and transport of emerging contaminants in Qingcaosha Reservoir. The reservoir, which supplies drinking water for nearly half of Shanghai's population, is located in Yangtze Delta. The integrated model was built by Delft3D suite, a fully integrated multidimensional modeling software. Atrazine and Bisphenol A (BPA) were selected as two representative emerging contaminants for the study in this reservoir. The hydrodynamic model was calibrated and validated against observations from 2011 to 2015 while the integrated model was calibrated against observations from 2014 to 2015 and then applied to explore the potential risk of high atrazine concentrations in the reservoir driven by agriculture activities. Our results show that the model is capable of describing the spatial and temporal patterns of water temperature, salinity and the dynamic distributions of two representative emerging contaminants (i.e. atrazine and BPA) in the reservoir. The physical and biodegradation processes in this study were found to play a crucial role in determining the fate and transport of atrazine and BPA in the reservoir. The model also provides an insight into the potential risk of emerging contaminants and possible mitigation thresholds. The integrated approach can be a very useful tool to support policy-makers in the future management of Qingcaosha Reservoir. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Catchment Models and Management Tools for diffuse Contaminants (Sediment, Phosphorus and Pesticides): DIFFUSE Project

    Science.gov (United States)

    Mockler, Eva; Reaney, Simeon; Mellander, Per-Erik; Wade, Andrew; Collins, Adrian; Arheimer, Berit; Bruen, Michael

    2017-04-01

    The agricultural sector is the most common suspected source of nutrient pollution in Irish rivers. However, it is also often the most difficult source to characterise due to its predominantly diffuse nature. Particulate phosphorus in surface water and dissolved phosphorus in groundwater are of particular concern in Irish water bodies. Hence the further development of models and indices to assess diffuse sources of contaminants are required for use by the Irish Environmental Protection Agency (EPA) to provide support for river basin planning. Understanding connectivity in the landscape is a vital component of characterising the source-pathway-receptor relationships for water-borne contaminants, and hence is a priority in this research. The DIFFUSE Project will focus on connectivity modelling and incorporation of connectivity into sediment, nutrient and pesticide risk mapping. The Irish approach to understanding and managing natural water bodies has developed substantially in recent years assisted by outputs from multiple research projects, including modelling and analysis tools developed during the Pathways and CatchmentTools projects. These include the Pollution Impact Potential (PIP) maps, which are an example of research output that is used by the EPA to support catchment management. The PIP maps integrate an understanding of the pollution pressures and mobilisation pathways and, using the source-pathways-receptor model, provide a scientific basis for evaluation of mitigation measures. These maps indicate the potential risk posed by nitrate and phosphate from diffuse agricultural sources to surface and groundwater receptors and delineate critical source areas (CSAs) as a means of facilitating the targeting of mitigation measures. Building on this previous research, the DIFFUSE Project will develop revised and new catchment managements tools focused on connectivity, sediment, phosphorus and pesticides. The DIFFUSE project will strive to identify the state

  5. Generalizing Source Geometry of Site Contamination by Simulating and Analyzing Analytical Solution of Three-Dimensional Solute Transport Model

    Directory of Open Access Journals (Sweden)

    Xingwei Wang

    2014-01-01

    Full Text Available Due to the uneven distribution of pollutions and blur edge of pollutant area, there will exist uncertainty of source term shape in advective-diffusion equation model of contaminant transport. How to generalize those irregular source terms and deal with those uncertainties is very critical but rarely studied in previous research. In this study, the fate and transport of contaminant from rectangular and elliptic source geometry were simulated based on a three-dimensional analytical solute transport model, and the source geometry generalization guideline was developed by comparing the migration of contaminant. The result indicated that the variation of source area size had no effect on pollution plume migration when the plume migrated as far as five times of source side length. The migration of pollution plume became slower with the increase of aquifer thickness. The contaminant concentration was decreasing with scale factor rising, and the differences among various scale factors became smaller with the distance to field increasing.

  6. Application of SPARROW modeling to understanding contaminant fate and transport from uplands to streams

    Science.gov (United States)

    Ator, Scott; Garcia, Ana Maria.

    2016-01-01

    Understanding spatial variability in contaminant fate and transport is critical to efficient regional water-quality restoration. An approach to capitalize on previously calibrated spatially referenced regression (SPARROW) models to improve the understanding of contaminant fate and transport was developed and applied to the case of nitrogen in the 166,000 km2 Chesapeake Bay watershed. A continuous function of four hydrogeologic, soil, and other landscape properties significant (α = 0.10) to nitrogen transport from uplands to streams was evaluated and compared among each of the more than 80,000 individual catchments (mean area, 2.1 km2) in the watershed. Budgets (including inputs, losses or net change in storage in uplands and stream corridors, and delivery to tidal waters) were also estimated for nitrogen applied to these catchments from selected upland sources. Most (81%) of such inputs are removed, retained, or otherwise processed in uplands rather than transported to surface waters. Combining SPARROW results with previous budget estimates suggests 55% of this processing is attributable to denitrification, 23% to crop or timber harvest, and 6% to volatilization. Remaining upland inputs represent a net annual increase in landscape storage in soils or biomass exceeding 10 kg per hectare in some areas. Such insights are important for planning watershed restoration and for improving future watershed models.

  7. Topsoil N-budget model in orchard farming to evaluate groundwater nitrate contamination

    Science.gov (United States)

    Wijayanti, Yureana; Budihardjo, Kadarwati; Sakamoto, Yasushi; Setyandito, Oki

    2017-12-01

    A small scale field research was conducted in an orchard farming area in Kofu, Japan, where nitrate contamination was found in groundwater. The purpose of assessing the leaching of nitrate in this study is to understand the transformation and transport process of N-source in topsoil that leads to nitrate contamination of groundwater. In order to calculate N-budget in the soil, the model was utilized to predict the nitrogen leaching. In this res earch, the N-budget model was modified to evaluate influence of precipitation and application pattern of fertilizer and manure compost. The result shows that at the time before the addition of manure compost and fertilizer, about 75% of fertilizer leach from topsoil. Every month, the average remaining nitrate in soil from fertilizer and manure compost are 22% and 50%, respectively. The accumulation of this monthly manure compost nitrate, which stored in soil, should be carefully monitored. It could become the potential source of nitrate leaching to groundwater in the future.

  8. Model evaluation of faecal contamination in coastal areas affected by urban rivers receiving combined sewer overflows.

    Science.gov (United States)

    Shibata, T; Kojima, K; Lee, S A; Furumai, H

    2014-01-01

    Odaiba seaside park is one of the most popular waterfronts in Tokyo Bay, but is easily affected by wet weather pollutant loads through combined sewer overflows (CSOs). The monitoring data of Escherichia coli clearly showed high faecal contamination after a rainfall event on 9-11 November 2007. We estimated the amounts of discharge volume and E. coli pollutant loads of urban rivers receiving CSO from rainfall chambers as well as pumping stations and primary effluent discharge. The result suggested that Sumida River and Meguro River were more influential to the Odaiba coastal area than other sources including the nearest wastewater treatment plant. Subsequently, we simulated the dynamic behaviour of E. coli by a three-dimensional (3D) hydro-dynamic and water quality model. The model simulation reproduced that E. coli concentration after the rainfall event increased rapidly at first and later gradually decreased. The simulations with and without inflow pollutant loads from urban rivers suggested that the E. coli concentration can be influenced by the Meguro River just after the rainfall event and Sumida River about 1 week later. From the spatial and temporal distribution of surface E. coli concentration, after at least 6 days from the rainfall event, high faecal contamination spread to the whole of the coastal area.

  9. Modelling and assessment of the impact of radiocesium and radiostrontium contamination in the Thermaikos Gulf, Greece

    International Nuclear Information System (INIS)

    Eleftheriou, G.; Monte, L.; Brittain, J.E.; Tsabaris, C.

    2015-01-01

    A radiological model for 137 Cs and 90 Sr dispersion in the marine environment of the Thermaikos Gulf, Greece, and the river catchments draining into the Gulf, is presented. The model, developed and implemented within the MOIRA-PLUS decision support system, integrates appropriate site-specific information. The model's performance has been tested using the available empirical 137 Cs activity concentration data in abiotic and biotic components of the gulf since the Chernobyl accident. Further, this paper describes the results of a modelling exercise performed within the IAEA's EMRAS II international modelling programme to estimate the environmental sensitivity of this characteristic Mediterranean coastal marine environment following radioactive contamination. The radiation doses to humans after a single hypothetical instantaneous deposition of 1000 Bq m −2 , assuming that all of their food intake from the marine pathway comes from the local environment, were calculated. The obtained results are consistent with estimates from other models for different coastal marine environments in the frame of the above-mentioned EMRAS exercise. - Highlights: • The Decision Support System (DSS) MOIRA-PLUS was customised to Thermaikos Gulf. • Model results were compared with empirical data to adjust parameter values. • The environmental sensitivity of the Gulf to 90 Sr and 137 Cs pollution was assessed. • Radiation doses from marine and fresh water pathways were compared. • The dose from fresh water pathways is notably higher than that from marine pathways

  10. Modelling and assessment of the impact of radiocesium and radiostrontium contamination in the Thermaikos Gulf, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Eleftheriou, G., E-mail: gelefthe@central.ntua.gr [Department of Physics, National Technical University of Athens (Greece); Institute of Oceanography, Hellenic Centre for Marine Research (Greece); Monte, L., E-mail: monte.luigi@fastwebnet.it [ENEA, Roma (Italy); Brittain, J.E. [Natural History Museum, University of Oslo (Norway); Tsabaris, C. [Institute of Oceanography, Hellenic Centre for Marine Research (Greece)

    2015-11-15

    A radiological model for {sup 137}Cs and {sup 90}Sr dispersion in the marine environment of the Thermaikos Gulf, Greece, and the river catchments draining into the Gulf, is presented. The model, developed and implemented within the MOIRA-PLUS decision support system, integrates appropriate site-specific information. The model's performance has been tested using the available empirical {sup 137}Cs activity concentration data in abiotic and biotic components of the gulf since the Chernobyl accident. Further, this paper describes the results of a modelling exercise performed within the IAEA's EMRAS II international modelling programme to estimate the environmental sensitivity of this characteristic Mediterranean coastal marine environment following radioactive contamination. The radiation doses to humans after a single hypothetical instantaneous deposition of 1000 Bq m{sup −2}, assuming that all of their food intake from the marine pathway comes from the local environment, were calculated. The obtained results are consistent with estimates from other models for different coastal marine environments in the frame of the above-mentioned EMRAS exercise. - Highlights: • The Decision Support System (DSS) MOIRA-PLUS was customised to Thermaikos Gulf. • Model results were compared with empirical data to adjust parameter values. • The environmental sensitivity of the Gulf to {sup 90}Sr and {sup 137}Cs pollution was assessed. • Radiation doses from marine and fresh water pathways were compared. • The dose from fresh water pathways is notably higher than that from marine pathways.

  11. An Intercomparison of Model Predictions for an Urban Contamination Resulting from the Explosion of a Radiological Dispersal Device

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Won Tae; Jeong, Hyo Jun; Kim, Eun Han; Han, Moon Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-03-15

    The METRO-K is a model for a radiological dose assessment due to a radioactive contamination in the Korean urban environment. The model has been taken part in the Urban Remediation Working Group within the IAEA's (International Atomic Energy Agency) EMRAS (Environmental Modeling for Radiation Safety) program. The Working Croup designed for the intercomparison of radioactive contamination to be resulted from the explosion of a radiological dispersal device in a hypothetical city. This paper dealt intensively with a part among a lot of predictive results which had been performed in the EMRAS program. The predictive results of three different models (METRO-K, RESRAD-RDD, CPHR) were submitted to the Working Group. The gap of predictive results was due to the difference of mathematical modeling approaches, parameter values, understanding of assessors. Even if final results (for example, dose rates from contaminated surfaces which might affect to a receptor) are similar, the understanding on the contribution of contaminated surfaces showed a great difference. Judging from the authors, it is due to the lack of understanding and information on radioactive terrors as well as the social and cultural gaps which assessors have been experienced. Therefore, it can be known that the experience of assessors and their subjective judgements might be important factors to get reliable results. If the acquisition of a little additional information is possible, it was identified that the METRO-K might be a useful tool for decision support against contamination resulting from radioactive terrors by improving the existing model.

  12. An Intercomparison of Model Predictions for an Urban Contamination Resulting from the Explosion of a Radiological Dispersal Device

    International Nuclear Information System (INIS)

    Hwang, Won Tae; Jeong, Hyo Jun; Kim, Eun Han; Han, Moon Hee

    2009-01-01

    The METRO-K is a model for a radiological dose assessment due to a radioactive contamination in the Korean urban environment. The model has been taken part in the Urban Remediation Working Group within the IAEA's (International Atomic Energy Agency) EMRAS (Environmental Modeling for Radiation Safety) program. The Working Croup designed for the intercomparison of radioactive contamination to be resulted from the explosion of a radiological dispersal device in a hypothetical city. This paper dealt intensively with a part among a lot of predictive results which had been performed in the EMRAS program. The predictive results of three different models (METRO-K, RESRAD-RDD, CPHR) were submitted to the Working Group. The gap of predictive results was due to the difference of mathematical modeling approaches, parameter values, understanding of assessors. Even if final results (for example, dose rates from contaminated surfaces which might affect to a receptor) are similar, the understanding on the contribution of contaminated surfaces showed a great difference. Judging from the authors, it is due to the lack of understanding and information on radioactive terrors as well as the social and cultural gaps which assessors have been experienced. Therefore, it can be known that the experience of assessors and their subjective judgements might be important factors to get reliable results. If the acquisition of a little additional information is possible, it was identified that the METRO-K might be a useful tool for decision support against contamination resulting from radioactive terrors by improving the existing model.

  13. Savannah River Laboratory DOSTOMAN code: a compartmental pathways computer model of contaminant transport

    International Nuclear Information System (INIS)

    King, C.M.; Wilhite, E.L.; Root, R.W. Jr.

    1985-01-01

    The Savannah River Laboratory DOSTOMAN code has been used since 1978 for environmental pathway analysis of potential migration of radionuclides and hazardous chemicals. The DOSTOMAN work is reviewed including a summary of historical use of compartmental models, the mathematical basis for the DOSTOMAN code, examples of exact analytical solutions for simple matrices, methods for numerical solution of complex matrices, and mathematical validation/calibration of the SRL code. The review includes the methodology for application to nuclear and hazardous chemical waste disposal, examples of use of the model in contaminant transport and pathway analysis, a user's guide for computer implementation, peer review of the code, and use of DOSTOMAN at other Department of Energy sites. 22 refs., 3 figs

  14. Modelling phytoremediation by the hyperaccumulating fern, Pteris vittata, of soils historically contaminated with arsenic.

    Science.gov (United States)

    Shelmerdine, Paula A; Black, Colin R; McGrath, Steve P; Young, Scott D

    2009-05-01

    Pteris vittata plants were grown on twenty-one UK soils contaminated with arsenic (As) from a wide range of natural and anthropogenic sources. Arsenic concentration was measured in fern fronds, soil and soil pore water collected with Rhizon samplers. Isotopically exchangeable soil arsenate was determined by equilibration with (73)As(V). Removal of As from the 21 soils by three sequential crops of P. vittata ranged between 0.1 and 13% of total soil As. Ferns grown on a soil subjected to long-term sewage sludge application showed reduced uptake of As because of high available phosphate concentrations. A combined solubility-uptake model was parameterised to enable prediction of phytoremediation success from estimates of soil As, 'As-lability' and soil pH. The model was used to demonstrate the remediation potential of P. vittata under different soil conditions and with contrasting assumptions regarding re-supply of the labile As pool from unavailable forms.

  15. Modeled de facto reuse and contaminants of emerging concern in drinking water source waters

    Science.gov (United States)

    Nguyen, Thuy; Westerhoff, Paul; Furlong, Edward T.; Kolpin, Dana W.; Batt, Angela L.; Mash, Heath E.; Schenck, Kathleen M.; Boone, J. Scott; Rice, Jacelyn; Glassmeyer, Susan T.

    2018-01-01

    De facto reuse is the percentage of drinking water treatment plant (DWTP) intake potentially composed of effluent discharged from upstream wastewater treatment plants (WWTPs). Results from grab samples and a De Facto Reuse in our Nation's Consumable Supply (DRINCS) geospatial watershed model were used to quantify contaminants of emerging concern (CECs) concentrations at DWTP intakes to qualitatively compare exposure risks obtained by the two approaches. Between nine and 71 CECs were detected in grab samples. The number of upstream WWTP discharges ranged from 0 to >1,000; comparative de facto reuse results from DRINCS ranged from 80% during lower streamflows. Correlation between chemicals detected and DRINCS modeling results were observed, particularly DWTPs withdrawing from midsize water bodies. This comparison advances the utility of DRINCS to identify locations of DWTPs for future CEC sampling and treatment technology testing.

  16. Modelling accumulation of radionuclides in terrestrial ecosystems originating from a long-term groundwater contamination

    Energy Technology Data Exchange (ETDEWEB)

    Gaerdenaes, Annemieke I. [Dept. of Soil and Environment, Swedish University of Agricultural Sciences (SLU), P.O. Box 7001, 750 07 Uppsala (Sweden); Eckersten, Henrik [Dept. of Ecology and Crop Production, SLU, P.O. Box 7042, 750 07 Uppsala (Sweden); Reinlert, Andre [Dept. of Physical Geography and Ecosystems Analysis, Lund University, 223 62 Lund (Sweden); MMT, Sven Kaellfelts Gata 11 SE 426 71 Vaestra Froelunda (Sweden); Gustafsson, David; Jansson, Per-Erik [Dept. Land and Water Resources, KTH, SE 100 44, Stockholm (Sweden); Ekstroem, Per-Anders [Facilia AB, Gustavlundsvaegen 151A, 167 51 Bromma (Sweden); Greger, Maria [Dept. of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm (Sweden)

    2014-07-01

    This study was conducted as part of the risk assessment of final deposits of nuclear fuel waste. The overall objective is to assess the possible accumulation of radionuclides in terrestrial ecosystems after an eventual long-term groundwater contamination. The specific objectives are to assess: i) What proportion of the contamination will accumulate in the soil-plant-system? ii) Where in the soil-plant- system will it accumulate? iii) Which ecosystem characteristics and radionuclides properties are important for the accumulation? and iv) Under which circumstances do losses from the ecosystems occur? We developed the dynamic model Tracey (Gaerdenaes et al. 2009) describing cycling of radionuclides in terrestrial ecosystems with high temporal resolution (1 day). The model is a multi-compartmental model in which fluxes and storage of radionuclides are described for different plant parts and soil pools in each of the 10 soil layers. The radionuclide fluxes are driven either by water or carbon fluxes. The water and the carbon fluxes are simulated with the dynamic, bio-geophysical Coup Model (Jansson and Karlberg, 2004). Tracey includes two root uptake approaches of radionuclides; (i) passive uptake driven by root water uptake and (ii) active uptake driven by plant growth. A linear approach describes the adsorption of radionuclides to soil particles and organic matter. Tracey was applied on two ecosystems with contrasting hydrology, the mixed Pinus-Picea forests found in the dry, elevated areas and the Alnus forests found in the wet, low-land areas of Uppland in central east Sweden. Different varieties of the two forest types were created by varying the root depth and radiation use efficiency. The climate was cold-temperate and based on 30-year daily weather data from Uppsala. The assumed groundwater contamination was close to 1 mg of an unspecified radionuclide per m2 and year. This load corresponds to 1 Bq per m{sup 2} and year of {sup 238}U, a common long

  17. Inverse modeling of the biodegradation of emerging organic contaminants in the soil-plant system

    OpenAIRE

    Hurtado, Carlos; Trapp, Stefan; Bayona, Josep M.

    2016-01-01

    Understanding the processes involved in the uptake and accumulation of organic contaminants into plants is very important to assess the possible human risk associated with. Biodegradation of emerging contaminants in plants has been observed, but kinetical studies are rare. In this study, we analyse experimental data on the uptake of emerging organic contaminants into lettuce derived in a greenhouse experiment. Measured soil, root and leaf concentrations from four contaminants were selected wi...

  18. A Cercla-Based Decision Model to Support Remedy Selection for an Uncertain Volume of Contaminants at a DOE Facility

    Energy Technology Data Exchange (ETDEWEB)

    Christine E. Kerschus

    1999-03-31

    The Paducah Gaseous Diffusion Plant (PGDP) operated by the Department of Energy is challenged with selecting the appropriate remediation technology to cleanup contaminants at Waste Area Group (WAG) 6. This research utilizes value-focused thinking and multiattribute preference theory concepts to produce a decision analysis model designed to aid the decision makers in their selection process. The model is based on CERCLA's five primary balancing criteria, tailored specifically to WAG 6 and the contaminants of concern, utilizes expert opinion and the best available engineering, cost, and performance data, and accounts for uncertainty in contaminant volume. The model ranks 23 remediation technologies (trains) in their ability to achieve the CERCLA criteria at various contaminant volumes. A sensitivity analysis is performed to examine the effects of changes in expert opinion and uncertainty in volume. Further analysis reveals how volume uncertainty is expected to affect technology cost, time and ability to meet the CERCLA criteria. The model provides the decision makers with a CERCLA-based decision analysis methodology that is objective, traceable, and robust to support the WAG 6 Feasibility Study. In addition, the model can be adjusted to address other DOE contaminated sites.

  19. A Cercla-Based Decision Model to Support Remedy Selection for an Uncertain Volume of Contaminants at a DOE Facility

    International Nuclear Information System (INIS)

    Christine E. Kerschus

    1999-01-01

    The Paducah Gaseous Diffusion Plant (PGDP) operated by the Department of Energy is challenged with selecting the appropriate remediation technology to cleanup contaminants at Waste Area Group (WAG) 6. This research utilizes value-focused thinking and multiattribute preference theory concepts to produce a decision analysis model designed to aid the decision makers in their selection process. The model is based on CERCLA's five primary balancing criteria, tailored specifically to WAG 6 and the contaminants of concern, utilizes expert opinion and the best available engineering, cost, and performance data, and accounts for uncertainty in contaminant volume. The model ranks 23 remediation technologies (trains) in their ability to achieve the CERCLA criteria at various contaminant volumes. A sensitivity analysis is performed to examine the effects of changes in expert opinion and uncertainty in volume. Further analysis reveals how volume uncertainty is expected to affect technology cost, time and ability to meet the CERCLA criteria. The model provides the decision makers with a CERCLA-based decision analysis methodology that is objective, traceable, and robust to support the WAG 6 Feasibility Study. In addition, the model can be adjusted to address other DOE contaminated sites

  20. CAirTOX, An inter-media transfer model for assessing indirect exposures to hazardous air contaminants

    International Nuclear Information System (INIS)

    McKone, T.E.

    1994-01-01

    Risk assessment is a quantitative evaluation of information on potential health hazards of environmental contaminants and the extent of human exposure to these contaminants. As applied to toxic chemical emissions to air, risk assessment involves four interrelated steps. These are (1) determination of source concentrations or emission characteristics, (2) exposure assessment, (3) toxicity assessment, and (4) risk characterization. These steps can be carried out with assistance from analytical models in order to estimate the potential risk associated with existing and future releases. CAirTOX has been developed as a spreadsheet model to assist in making these types of calculations. CAirTOX follows an approach that has been incorporated into the CalTOX model, which was developed for the California Department of Toxic Substances Control, With CAirTOX, we can address how contaminants released to an air basin can lead to contamination of soil, food, surface water, and sediments. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify uncertainty in multimedia, multiple-pathway exposure assessments. The capacity to explicitly address uncertainty has been incorporated into the model in two ways. First, the spreadsheet form of the model makes it compatible with Monte-Carlo add-on programs that are available for uncertainty analysis. Second, all model inputs are specified in terms of an arithmetic mean and coefficient of variation so that uncertainty analyses can be carried out

  1. Experimental Study of Airborne Contaminant Migration in an Aircraft Cabin Model

    Science.gov (United States)

    Poussou, Stephane; Sojka, Paul; Plesniak, Michael

    2007-11-01

    The cabin air ventilation system in wide body jetliners is designed to provide a comfortable and controlled environment for passengers. Inside the cabin, the air flows continuously from overhead vents into sidewall exhausts, forming a circular pattern designed to minimize cross flow between adjacent seat rows. However, spreading of gaseous or particulate contaminants is possible when flight attendants or passengers walk along an aisle, perturbing the ventilation flow. Such unsteady flow perturbations have been found to alter the cabin air distribution and quality. A better fundamental understanding of the turbulent transport phenomena is needed to improve air quality monitoring and control systems and to validate numerical simulations. The velocity field in a 15:1 model of a simplified aircraft cabin is probed to investigate the wake of a rectangular body moving through a steady two-dimensional flow at a Reynolds number (based on body height) of the order of 50,000. Planar Laser Induced Fluorescence is used to visualize wake structure and scalar contaminant transport. The interaction between the wake and the ventilation flow is measured with PIV. The data are compared to numerical studies of cabin airflows in the literature.

  2. A compositional multiphase model for groundwater contamination by petroleum products: 2. Numerical solution

    Science.gov (United States)

    Baehr, Arthur L.; Corapcioglu, M. Yavuz

    1987-01-01

    In this paper we develop a numerical solution to equations developed in part 1 (M. Y. Corapcioglu and A. L. Baehr, this issue) to predict the fate of an immiscible organic contaminant such as gasoline in the unsaturated zone subsequent to plume establishment. This solution, obtained by using a finite difference scheme and a method of forward projection to evaluate nonlinear coefficients, provides estimates of the flux of solubilized hydrocarbon constituents to groundwater from the portion of a spill which remains trapped in a soil after routine remedial efforts to recover the product have ceased. The procedure was used to solve the one-dimensional (vertical) form of the system of nonlinear partial differential equations defining the transport for each constituent of the product. Additionally, a homogeneous, isothermal soil with constant water content was assumed. An equilibrium assumption partitions the constituents between air, water, adsorbed, and immiscible phases. Free oxygen transport in the soil was also simulated to provide an upper bound estimate of aerobic biodgradation rates. Results are presented for a hypothetical gasoline consisting of eight groups of hydrocarbon constituents. Rates at which hydrocarbon mass is removed from the soil, entering either the atmosphere or groundwater, or is biodegraded are presented. A significant sensitivity to model parameters, particularly the parameters characterizing diffusive vapor transport, was discovered. We conclude that hydrocarbon solute composition in groundwater beneath a gasoline contaminated soil would be heavily weighted toward aromatic constituents like benzene, toluene, and xylene.

  3. Modelling the transport of solid contaminants originated from a point source

    Science.gov (United States)

    Salgueiro, Dora V.; Conde, Daniel A. S.; Franca, Mário J.; Schleiss, Anton J.; Ferreira, Rui M. L.

    2017-04-01

    The solid phases of natural flows can comprise an important repository for contaminants in aquatic ecosystems and can propagate as turbidity currents generating a stratified environment. Contaminants can be desorbed under specific environmental conditions becoming re-suspended, with a potential impact on the aquatic biota. Forecasting the distribution of the contaminated turbidity current is thus crucial for a complete assessment of environmental exposure. In this work we validate the ability of the model STAV-2D, developed at CERIS (IST), to simulate stratified flows such as those resulting from turbidity currents in complex geometrical environments. The validation involves not only flow phenomena inherent to flows generated by density imbalance but also convective effects brought about by the complex geometry of the water basin where the current propagates. This latter aspect is of paramount importance since, in real applications, currents may propagate in semi-confined geometries in plan view, generating important convective accelerations. Velocity fields and mass distributions obtained from experiments carried out at CERIS - (IST) are used as validation data for the model. The experimental set-up comprises a point source in a rectangular basin with a wall placed perpendicularly to the outer walls. Thus generates a complex 2D flow with an advancing wave front and shocks due to the flow reflection from the walls. STAV-2D is based on the depth- and time-averaged mass and momentum equations for mixtures of water and sediment, understood as continua. It is closed in terms of flow resistance and capacity bedload discharge by a set of classic closure models and a specific high concentration formulation. The two-layer model is derived from layer-averaged Navier-Stokes equations, resulting in a system of layer-specific non-linear shallow-water equations, solved through explicit first or second-order schemes. According to the experimental data for mass distribution, the

  4. Assessment of groundwater contamination risk using hazard quantification, a modified DRASTIC model and groundwater value, Beijing Plain, China.

    Science.gov (United States)

    Wang, Junjie; He, Jiangtao; Chen, Honghan

    2012-08-15

    Groundwater contamination risk assessment is an effective tool for groundwater management. Most existing risk assessment methods only consider the basic contamination process based upon evaluations of hazards and aquifer vulnerability. In view of groundwater exploitation potentiality, including the value of contamination-threatened groundwater could provide relatively objective and targeted results to aid in decision making. This study describes a groundwater contamination risk assessment method that integrates hazards, intrinsic vulnerability and groundwater value. The hazard harmfulness was evaluated by quantifying contaminant properties and infiltrating contaminant load, the intrinsic aquifer vulnerability was evaluated using a modified DRASTIC model and the groundwater value was evaluated based on groundwater quality and aquifer storage. Two groundwater contamination risk maps were produced by combining the above factors: a basic risk map and a value-weighted risk map. The basic risk map was produced by overlaying the hazard map and the intrinsic vulnerability map. The value-weighted risk map was produced by overlaying the basic risk map and the groundwater value map. Relevant validation was completed by contaminant distributions and site investigation. Using Beijing Plain, China, as an example, thematic maps of the three factors and the two risks were generated. The thematic maps suggested that landfills, gas stations and oil depots, and industrial areas were the most harmful potential contamination sources. The western and northern parts of the plain were the most vulnerable areas and had the highest groundwater value. Additionally, both the basic and value-weighted risk classes in the western and northern parts of the plain were the highest, indicating that these regions should deserve the priority of concern. Thematic maps should be updated regularly because of the dynamic characteristics of hazards. Subjectivity and validation means in assessing the

  5. UNCERT: geostatistics, uncertainty analysis and visualization software applied to groundwater flow and contaminant transport modeling

    International Nuclear Information System (INIS)

    Wingle, W.L.; Poeter, E.P.; McKenna, S.A.

    1999-01-01

    UNCERT is a 2D and 3D geostatistics, uncertainty analysis and visualization software package applied to ground water flow and contaminant transport modeling. It is a collection of modules that provides tools for linear regression, univariate statistics, semivariogram analysis, inverse-distance gridding, trend-surface analysis, simple and ordinary kriging and discrete conditional indicator simulation. Graphical user interfaces for MODFLOW and MT3D, ground water flow and contaminant transport models, are provided for streamlined data input and result analysis. Visualization tools are included for displaying data input and output. These include, but are not limited to, 2D and 3D scatter plots, histograms, box and whisker plots, 2D contour maps, surface renderings of 2D gridded data and 3D views of gridded data. By design, UNCERT's graphical user interface and visualization tools facilitate model design and analysis. There are few built in restrictions on data set sizes and each module (with two exceptions) can be run in either graphical or batch mode. UNCERT is in the public domain and is available from the World Wide Web with complete on-line and printable (PDF) documentation. UNCERT is written in ANSI-C with a small amount of FORTRAN77, for UNIX workstations running X-Windows and Motif (or Lesstif). This article discusses the features of each module and demonstrates how they can be used individually and in combination. The tools are applicable to a wide range of fields and are currently used by researchers in the ground water, mining, mathematics, chemistry and geophysics, to name a few disciplines. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  6. Modeling the level of contamination of Staphylococcus aureus in ready-to-eat kimbab in Korea.

    Science.gov (United States)

    Bahk, Gyung-Jin; Hong, Chong-Hae; Oh, Deog-Hwan; Ha, Sang-Do; Park, Ki-Hwan; Todd, Ewen C D

    2006-06-01

    The risk of Staphylococcus aureus in ready-to-eat kimbab (rice rolled in laver) sold in Korea was evaluated by a mathematical modeling approach. Four nodes were constructed from preparation at retail to consumption. A predictive microbial growth model and survey data were combined with probabilistic modeling to simulate the level of S. aureus in a single kimbab at the time of consumption. We estimated the mean level of S. aureus to be 2.92 log CFU/g for a typical kimbab (150 to 200 g each) at the time of consumption. Our model also showed that 29.73% of the kimbabs had > or = 100,000 S. aureus CFU/g, which poses some risk of illness, since some level of enterotoxin would be expected from toxigenic strains. However, because of the lack of dose-response models for staphylococcal enterotoxin, the final level of S. aureus in the kimbabs could not be used to estimate how many people would become ill from eating them. Correlation sensitivity results showed that consumer eating patterns and initial contamination levels at retail stores were the most significant risk factors for illness and that temperature control under 10 degrees C was a critical control point in kimbab retail establishments to prevent the growth of S. aureus.

  7. An integrated logit model for contamination event detection in water distribution systems.

    Science.gov (United States)

    Housh, Mashor; Ostfeld, Avi

    2015-05-15

    The problem of contamination event detection in water distribution systems has become one of the most challenging research topics in water distribution systems analysis. Current attempts for event detection utilize a variety of approaches including statistical, heuristics, machine learning, and optimization methods. Several existing event detection systems share a common feature in which alarms are obtained separately for each of the water quality indicators. Unifying those single alarms from different indicators is usually performed by means of simple heuristics. A salient feature of the current developed approach is using a statistically oriented model for discrete choice prediction which is estimated using the maximum likelihood method for integrating the single alarms. The discrete choice model is jointly calibrated with other components of the event detection system framework in a training data set using genetic algorithms. The fusing process of each indicator probabilities, which is left out of focus in many existing event detection system models, is confirmed to be a crucial part of the system which could be modelled by exploiting a discrete choice model for improving its performance. The developed methodology is tested on real water quality data, showing improved performances in decreasing the number of false positive alarms and in its ability to detect events with higher probabilities, compared to previous studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. MOIRA models and methodologies for assessing the effectiveness of countermeasures in complex aquatic systems contaminated by radionuclides

    International Nuclear Information System (INIS)

    Monte, L.; Haakanson, L.; Gallego Diaz, E.

    1999-01-01

    The present report is composed of a set of articles written by the partners of the MOIRA project (a model-based computerized system for management support to identify optimal remedial strategies for restoring radionuclide contaminated aquatic ecosystems and drainage areas). The report describes models for predicting the behaviour of radionuclides in complex aquatic systems and the effects of countermeasures for their restoration [it

  9. Modeling the pH-mediated Extraction of Ionizable Organic Contaminants to Improve the Quality of Municipal Sewage Sludge Destined for Land Application

    OpenAIRE

    Venkatesan, Arjun K.; Halden, Rolf U.

    2016-01-01

    A model was developed to assess the impact of adding acids and bases to processed municipal sewage sludge (MSS) to mobilize contaminants, facilitating their removal from sludge by flushing prior to land application. Among 312 organic contaminants documented to occur in U.S. MSS, 71 or 23% were identified as ionizable organic contaminants (IOCs), contributing a disproportionately large fraction of 82% of the total mass of sludge-borne contaminants. Detected IOCs included 57 pharmaceuticals and...

  10. An adaptive hybrid EnKF-OI scheme for efficient state-parameter estimation of reactive contaminant transport models

    KAUST Repository

    El Gharamti, Mohamad; Valstar, Johan R.; Hoteit, Ibrahim

    2014-01-01

    Reactive contaminant transport models are used by hydrologists to simulate and study the migration and fate of industrial waste in subsurface aquifers. Accurate transport modeling of such waste requires clear understanding of the system's parameters, such as sorption and biodegradation. In this study, we present an efficient sequential data assimilation scheme that computes accurate estimates of aquifer contamination and spatially variable sorption coefficients. This assimilation scheme is based on a hybrid formulation of the ensemble Kalman filter (EnKF) and optimal interpolation (OI) in which solute concentration measurements are assimilated via a recursive dual estimation of sorption coefficients and contaminant state variables. This hybrid EnKF-OI scheme is used to mitigate background covariance limitations due to ensemble under-sampling and neglected model errors. Numerical experiments are conducted with a two-dimensional synthetic aquifer in which cobalt-60, a radioactive contaminant, is leached in a saturated heterogeneous clayey sandstone zone. Assimilation experiments are investigated under different settings and sources of model and observational errors. Simulation results demonstrate that the proposed hybrid EnKF-OI scheme successfully recovers both the contaminant and the sorption rate and reduces their uncertainties. Sensitivity analyses also suggest that the adaptive hybrid scheme remains effective with small ensembles, allowing to reduce the ensemble size by up to 80% with respect to the standard EnKF scheme. © 2014 Elsevier Ltd.

  11. An adaptive hybrid EnKF-OI scheme for efficient state-parameter estimation of reactive contaminant transport models

    KAUST Repository

    El Gharamti, Mohamad

    2014-09-01

    Reactive contaminant transport models are used by hydrologists to simulate and study the migration and fate of industrial waste in subsurface aquifers. Accurate transport modeling of such waste requires clear understanding of the system\\'s parameters, such as sorption and biodegradation. In this study, we present an efficient sequential data assimilation scheme that computes accurate estimates of aquifer contamination and spatially variable sorption coefficients. This assimilation scheme is based on a hybrid formulation of the ensemble Kalman filter (EnKF) and optimal interpolation (OI) in which solute concentration measurements are assimilated via a recursive dual estimation of sorption coefficients and contaminant state variables. This hybrid EnKF-OI scheme is used to mitigate background covariance limitations due to ensemble under-sampling and neglected model errors. Numerical experiments are conducted with a two-dimensional synthetic aquifer in which cobalt-60, a radioactive contaminant, is leached in a saturated heterogeneous clayey sandstone zone. Assimilation experiments are investigated under different settings and sources of model and observational errors. Simulation results demonstrate that the proposed hybrid EnKF-OI scheme successfully recovers both the contaminant and the sorption rate and reduces their uncertainties. Sensitivity analyses also suggest that the adaptive hybrid scheme remains effective with small ensembles, allowing to reduce the ensemble size by up to 80% with respect to the standard EnKF scheme. © 2014 Elsevier Ltd.

  12. Quality assurance of sterilized products: verification of a model relating frequency of contaminated items and increasing radiation dose

    International Nuclear Information System (INIS)

    Khan, A.A.; Tallentire, A.; Dwyer, J.

    1977-01-01

    Values of the γ-radiation resistance parameters (k and n of the 'multi-hit' expression) for Bacillus pumilus E601 spores and Serratia marcescens cells have been determined and the constancy of values for a given test condition demonstrated. These organisms, differing by a factor of about 50 in k value, have been included in a laboratory test system for use in verification of a model describing the dependence of the proportion of contaminated items in a population of items on radiation dose. The proportions of contaminated units of the test system at various γ-radiation doses have been measured for different initial numbers and types of organisms present in units either singly or together. Using the model, the probabilities of contaminated units for corresponding sets of conditions have been evaluated together with associated variances. Measured proportions and predicted probabilities agree well, showing that the model holds in a laboratory contrived situation. (author)

  13. HTO transfer from contaminated surfaces to the atmosphere: a database for model validation

    International Nuclear Information System (INIS)

    Davis, P.A.; Amiro, B.D.; Workman, W.J.G.; Corbett, B.J.

    1996-12-01

    This report comprises a detailed database that can be used to validate models of the emission of tritiated water vapour (HTO) from natural contaminated surfaces to the atmosphere. The data were collected in 1992 July during an intensive field study based on the flux-gradient method of micrometeorology. The measurements were made over a wetland area at the Chalk River Laboratories, and over a grassed field near the Pickering Nuclear Generating Station. The study sites, the sampling protocols and the analytical techniques are described in detail, and the measured fluxes are presented. The report also contains a detailed listing of HTO concentrations in air at two heights, HTO concentrations in the source compartments (soil, surface water and vegetation), supporting meteorological data, and various vegetation and soil properties. The uncertainties in all of the measured data are estimated. (author). 15 refs., 23 tabs., 9 figs

  14. Sources of contamination and modelled pollutant trajectories in a Mediterranean harbour (Tarragona, Spain).

    Science.gov (United States)

    Mestres, M; Sierra, J P; Mösso, C; Sánchez-Arcilla, A

    2010-06-01

    The proximity of commercial harbours to residential areas and the growing environmental awareness of society have led most port authorities to include environmental management within their administration plan. Regarding water quality, it is necessary to have the capacity and tools to deal with contamination episodes that may damage marine ecosystems and human health, but also affect the normal functioning of harbours. This paper presents a description of the main pollutant sources in Tarragona Harbour (Spain), and a numerical analysis of several pollution episodes based on the Port Authority's actual environmental concerns. The results show that pollution generated inside the harbour tends to remain confined within the port, whereas it is very likely that oil spills from a nearby monobuoy may affect the neighbouring beaches. The present combination of numerical models proves itself a useful tool to assess the environmental risk associated to harbour activities and potential pollution spills.

  15. Asymptotic properties of Pearson's rank-variate correlation coefficient under contaminated Gaussian model.

    Science.gov (United States)

    Ma, Rubao; Xu, Weichao; Zhang, Yun; Ye, Zhongfu

    2014-01-01

    This paper investigates the robustness properties of Pearson's rank-variate correlation coefficient (PRVCC) in scenarios where one channel is corrupted by impulsive noise and the other is impulsive noise-free. As shown in our previous work, these scenarios that frequently encountered in radar and/or sonar, can be well emulated by a particular bivariate contaminated Gaussian model (CGM). Under this CGM, we establish the asymptotic closed forms of the expectation and variance of PRVCC by means of the well known Delta method. To gain a deeper understanding, we also compare PRVCC with two other classical correlation coefficients, i.e., Spearman's rho (SR) and Kendall's tau (KT), in terms of the root mean squared error (RMSE). Monte Carlo simulations not only verify our theoretical findings, but also reveal the advantage of PRVCC by an example of estimating the time delay in the particular impulsive noise environment.

  16. Contaminant transport modelling in tidal influenced water body for low level liquid waste discharge out

    International Nuclear Information System (INIS)

    Singh, Sanjay; Naidu, Velamala Simhadri

    2018-01-01

    Low level liquid waste is generated from nuclear reactor operation and reprocessing of spent fuel. This waste is discharged into the water body after removing bulk of its radioactivity. Dispersion of contaminant mainly depends on location of outfall and hydrodynamics of water body. For radiological impact assessment, in most of the analytical formulations, source term is taken as continuous release. However, this may not be always true as the water level is influenced by tidal movement and the selected outfall may come under intertidal zone in due course of the tidal cycle. To understand these phenomena, a case study has been carried out to evaluate hydrodynamic characteristics and dilution potential of outfall located in inter-tidal zone using numerical modelling

  17. Kinetics of Uranium(VI) Desorption from Contaminated Sediments: Effect of Geochemical Conditions and Model Evaluation

    International Nuclear Information System (INIS)

    Liu, Chongxuan; Shi, Zhenqing; Zachara, John M.

    2009-01-01

    Stirred-flow cell experiments were performed to investigate the kinetics of uranyl (U(VI)) desorption from a contaminated sediment collected from the Hanford 300 Area at the US Department of Energy (DOE) Hanford Site, Washington. Three influent solutions of variable pH, Ca and carbonate concentrations that affected U(VI) aqueous and surface speciation were used under dynamic flow conditions to evaluate the effect of geochemical conditions on the rate of U(VI) desorption. The measured rate of U(VI) desorption varied with solution chemical composition that evolved as a result of thermodynamic and kinetic interactions between the influent solutions and sediment. The solution chemical composition that led to a lower equilibrium U(VI) sorption to the solid phase yielded a faster desorption rate. The experimental results were used to evaluate a multi-rate, surface complexation model (SCM) that has been proposed to describe U(VI) desorption kinetics in the Hanford sediment that contained complex sorbed U(VI) species in mass transfer limited domains. The model was modified and supplemented by including multi-rate, ion exchange reactions to describe the geochemical interactions between the solutions and sediment. With the same set of model parameters, the modified model reasonably well described the evolution of major ions and the rates of U(VI) desorption under variable geochemical and flow conditions, implying that the multi-rate SCM is an effective way to describe U(VI) desorption kinetics in subsurface sediments

  18. Zinc and lead transfer in a contaminated roadside soil: Experimental study and modeling

    International Nuclear Information System (INIS)

    Hanna, K.; Lassabatere, L.; Bechet, B.

    2009-01-01

    The application of a surface complexation model to simulate the sorption of metals on single sorbents is very well investigated, but very little is known regarding the use of surface complexation modeling to simulate the metal mobility in contaminated roadside soils. The overall objective of this study was to examine whether the use of the surface complexation model (SCM) could correctly describe the migration of zinc and lead in roadside soil under various physicochemical conditions. The release and transport of Zn and Pb was studied by means of batch reactors and saturated chromatography columns. Soil batch experiments were conducted to evaluate the effects of pH variation and ionic strength on the metal mobility from soil. Elution of Pb and Zn was examined in column experiments by using acetic acid at pH5 and EDTA at pH7. The modeling work has focused on the development of a SCM using MINTEQ2 database incorporated in PHREEQC-2 to describe the interactions between trace metals and the main mineral soil components (quartz, iron and aluminum oxides). In this study, it was found that the SCM was able to simulate the mobility of metals from soil by assuming one mononuclear surface reaction between one solution species (Me 2+ ) and one type of site on the surface of soil dominant sorbents

  19. A geoprocessing model for the selection of populations most affected by diffuse industrial contamination: the case of oil refinery plants

    Directory of Open Access Journals (Sweden)

    Roberto Pasetto

    2013-03-01

    Full Text Available INTRODUCTION. A method to select populations living in areas affected by diffuse environmental contamination is presented, with particular regard to oil refineries, in the Italian context. The reasons to use municipality instead of census tract populations for environment and health small-area studies of contaminated sites are discussed. METHODS. Populations most affected by diffuse environmental contamination are identified through a geoprocessing model. Data from the national census 2001 were used to estimate census tract level populations. A geodatabase was developed using the municipality and census tract layers provided by the Italian National Bureau of Statistics (ISTAT. The orthophotos of the Italian territory - year 2006 - available on the geographic information systems (GIS of the National Cartographic Portal, were considered. The area within 2 km from the plant border was used as an operational definition to identify the area at major contamination. RESULTS. The geoprocessing model architecture is presented. The results of its application to the selection of municipality populations in a case study are shown. CONCLUSIONS. The application of the proposed geoprocessing model, the availability of long time series of mortality and morbidity data, and a quali-quantitative estimate of contamination over time, could allow an appraisal of the health status of populations affected by oil refinery emissions.

  20. Mercury emission and dispersion models from soils contaminated by cinnabar mining and metallurgy.

    Science.gov (United States)

    Llanos, Willians; Kocman, David; Higueras, Pablo; Horvat, Milena

    2011-12-01

    The laboratory flux measurement system (LFMS) and dispersion models were used to investigate the kinetics of mercury emission flux (MEF) from contaminated soils. Representative soil samples with respect to total Hg concentration (26-9770 μg g(-1)) surrounding a decommissioned mercury-mining area (Las Cuevas Mine), and a former mercury smelter (Cerco Metalúrgico de Almadenejos), in the Almadén mercury mining district (South Central Spain), were collected. Altogether, 14 samples were analyzed to determine the variation in mercury emission flux (MEF) versus distance from the sources, regulating two major environmental parameters comprising soil temperature and solar radiation. In addition, the fraction of the water-soluble mercury in these samples was determined in order to assess how MEF from soil is related to the mercury in the aqueous soil phase. Measured MEFs ranged from less than 140 to over 10,000 ng m(-2) h(-1), with the highest emissions from contaminated soils adjacent to point sources. A significant decrease of MEF was then observed with increasing distance from these sites. Strong positive effects of both temperature and solar radiation on MEF was observed. Moreover, MEF was found to occur more easily in soils with higher proportions of soluble mercury compared to soils where cinnabar prevails. Based on the calculated Hg emission rates and with the support of geographical information system (GIS) tools and ISC AERMOD software, dispersion models for atmospheric mercury were implemented. In this way, the gaseous mercury plume generated by the soil-originated emissions at different seasons was modeled. Modeling efforts revealed that much higher emissions and larger mercury plumes are generated in dry and warm periods (summer), while the plume is smaller and associated with lower concentrations of atmospheric mercury during colder periods with higher wind activity (fall). Based on the calculated emissions and the model implementation, yearly emissions from

  1. Human Environmental Disease Network: A computational model to assess toxicology of contaminants.

    Science.gov (United States)

    Taboureau, Olivier; Audouze, Karine

    2017-01-01

    During the past decades, many epidemiological, toxicological and biological studies have been performed to assess the role of environmental chemicals as potential toxicants associated with diverse human disorders. However, the relationships between diseases based on chemical exposure rarely have been studied by computational biology. We developed a human environmental disease network (EDN) to explore and suggest novel disease-disease and chemical-disease relationships. The presented scored EDN model is built upon the integration of systems biology and chemical toxicology using information on chemical contaminants and their disease relationships reported in the TDDB database. The resulting human EDN takes into consideration the level of evidence of the toxicant-disease relationships, allowing inclusion of some degrees of significance in the disease-disease associations. Such a network can be used to identify uncharacterized connections between diseases. Examples are discussed for type 2 diabetes (T2D). Additionally, this computational model allows confirmation of already known links between chemicals and diseases (e.g., between bisphenol A and behavioral disorders) and also reveals unexpected associations between chemicals and diseases (e.g., between chlordane and olfactory alteration), thus predicting which chemicals may be risk factors to human health. The proposed human EDN model allows exploration of common biological mechanisms of diseases associated with chemical exposure, helping us to gain insight into disease etiology and comorbidity. This computational approach is an alternative to animal testing supporting the 3R concept.

  2. Calculating external doses from contaminated soil with the computer model SOILD

    International Nuclear Information System (INIS)

    Chen, Y.; LePoire, D.; Yu, C.

    1991-01-01

    The SOILD computer model was developed for calculating the effective dose equivalent from external exposure to distributed gamma sources in soil. It is designed to assess external doses under various exposure scenarios that may be encountered in environmental restoration programs. The model's four major functional features address (a) dose versus source depth in soil, (b) shielding of clean cover soil, (c) area of contamination, and (d) nonuniform distribution of sources. The model can also adjust doses when there are variations in soil densities for both source and cover soils. It is supported by a data base of ∼500 radionuclides. A sample calculation was performed by SOILD to determine the effective dose equivalent for a uniform source distribution in soil. The soil density was assumed to be 1.6 g/cm 3 , and the source strength was assumed to be 1 pCi/cm 3 . The following radionuclides were studied: 60 C, 131 I, 137+D Cs, 238+D U, and 226+D Ra ('+D' denotes the parent nuclide and daughters)

  3. RESRAD-BUILD: A model to estimate dose from contaminated structures. Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    The RESRAD-BUILD model is an exposure pathway and analysis code used to determine whether radiologically contaminated buildings and structures can be free released for a specific land use (e.g., residential or industrial). The model provides estimates of dose to a hypothetical receptor from the structure. The RESRAD-BUILD technology can calculate dose from variety of site-specific hypothetical scenarios, decay-time intervals, and radionuclides. When using the RESRAD-BUILD code, specific project assumptions must be developed with the appropriate regulatory agencies, especially the cleanup criteria and the exposure scenario to be used. The C Reactor demonstration of RESRAD-BUILD modeled hypothetical future use of below grade portions of the reactor building complex. A residential exposure scenario with a cleanup criteria of 15 mrem/yr above background (Environmental Protection Agency [EPA] draft guidance) was used to coordinate decommissioning with adjacent ongoing remedial actions conducted in accordance with an existing Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) Record of Decision. This paper gives a description of the technology and discusses its performance, applications, cost, regulatory and policy issues, and lessons learned.

  4. RESRAD-Build: A model to estimate dose from contaminated structures. Innovative technology summary report

    International Nuclear Information System (INIS)

    1998-12-01

    The RESRAD-BUILD model is an exposure pathway and analysis code used to determine whether radiologically contaminated buildings and structures can be free released for a specific land use (e.g., residential or industrial). The model provides estimates of dose to a hypothetical receptor from the structure. The RESRAD-BUILD technology can calculate dose from variety of site-specific hypothetical scenarios, decay-time intervals, and radionuclides. When using the RESRAD-BUILD code, specific project assumptions must be developed with the appropriate regulatory agencies, especially the cleanup criteria and the exposure scenario to be used. The C Reactor demonstration of RESRAD-BUILD modeled hypothetical future use of below grade portions of the reactor building complex. A residential exposure scenario with a cleanup criteria of 15 mrem/yr above background (Environmental Protection Agency [EPA] draft guidance) was used to coordinate decommissioning with adjacent ongoing remedial actions conducted in accordance with an existing Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) Record of Decision. This paper gives a description of the technology and discusses its performance, applications, cost, regulatory and policy issues, and lessons learned

  5. Stochastic Radiative Transfer Model for Contaminated Rough Surfaces: A Framework for Detection System Design

    Science.gov (United States)

    2013-11-01

    example for the detection of a potassium chlorate contaminated “car” with a CO2 tunable laser system. 15. SUBJECT TERMS Radiative transfer...detector m-out-of-n detector Potassium chlorate Probability theory System performance Probability of detection and false alarm iii...for the detection of a potassium chlorate contaminated “car” with a CO2 tunable laser system. Subject Terms Radiative transfer, contaminated

  6. Environmental Modelling of Remediation of Urban Contaminated Areas. Report of the Urban Remediation Working Group of EMRAS Theme 2

    International Nuclear Information System (INIS)

    2012-01-01

    The Urban Remediation Working Group of the International Atomic Energy Agency's EMRAS (Environmental Modelling for RAdiation Safety) programme was concerned with remediation assessment for urban areas contaminated with dispersed radionuclides. Types of events that could result in dispersal or deposition of radionuclides in an urban situation include both intentional and unintentional events, and releases could range from major events involving a nuclear facility to small events such as a transportation accident. The primary objective of the Urban Remediation Working Group was (1) to test and improve the prediction of dose rates and cumulative doses to humans for urban areas contaminated with dispersed radionuclides, including prediction of changes in radionuclide concentrations or dose rates as a function of location and time; (2) to identify the most important pathways for human exposure; and (3) to predict the reduction in radionuclide concentrations, dose rates, or doses expected to result from various countermeasures or remediation efforts. Specific objectives of the Working Group have included (1) the identification of realistic scenarios for a wide variety of situations, (2) comparison and testing of approaches and models for assessing the significance of a given contamination event and for guiding decisions about countermeasures or remediation measures implemented to reduce doses to humans or to clean up the contaminated area, and (3) improving the understanding of processes and situations that affect the spread of contamination to aid in the development of appropriate models and parameter values for use in assessment of these situations. The major activities of the Working Group have included three areas. The first of these was a review of the available modelling approaches and computer models for use in assessing urban contamination and potential countermeasures or remediation activities. The second area of work was a modelling exercise based on data

  7. A stratigraphic model to support remediation of groundwater contamination in the southern San Francisco Bay area

    International Nuclear Information System (INIS)

    Steinpress, M.G.

    1993-01-01

    Some early regional studies in the southern San Francisco Bay Area applied the term 'older bay mud' to Wisconsin and older deposits thought to be estuarine in origin. This outdated interpretation has apparently contributed to an expectation of laterally-continuous aquifers and aquitards. In fact, heterogeneous alluvial deposits often create complex hydrogeologic settings that defy simple remedial approaches. A more useful stratigraphic model provides a foundation for conducting site investigations and assessing the feasibility of remediation. A synthesis of recent regional studies and drilling results at one site on the southwest margin of the Bay indicate that the upper quaternary stratigraphy consists of four primary units in the upper 200 feet of sediments (oldest to youngest): (1) Illinoian glacial-age alluvium (an important groundwater source); (2) Sangamon interglacial-age deposits, which include fine-grained alluvial deposits and estuarine deposits equivalent to the Yerba Buena Mud (a regional confining layer); (3) Wisconsin glacial-age alluvial fan and floodplain deposits; and (4) Holocene interglacial-age sediments, which include fine-grained alluvial and estuarine deposits equivalent to the 'younger bay mud'. Remedial investigations generally focus on groundwater contamination in the Wisconsin and Holocene alluvial deposits. Detailed drilling results indicate that narrow sand and gravel channels occur in anastomosing patterns within a Wisconsin to Holocene floodplain sequence dominated by interchannel silts and clays. The identification of these small-scale high-permeability conduits is critical to understanding and predicting contaminant transport on a local scale. Discontinuous site-specific aquitards do not provide competent separation where stacked channels occur and the correlation of aquitards over even small distance is often tenuous at best

  8. A two-dimensional model for the analysis of radioactive waste contamination in soils: the integral transform method

    International Nuclear Information System (INIS)

    Leal, M.A.; Ruperti Junior, N.J.; Cotta, R.M.

    1997-01-01

    A two-dimensional model for the flow and mass transfer of radioactive waste in porous media is investigated. The flow equations are modeled under steady-state Darcy regime assumptions, subjected to discrete boundary source terms. The mass transfer of the contaminant is modeled through the transient convection-diffusion equation, allowing for variable dispersivity coefficients and boundary source functions. The Generalized Integral Transform Technique (GITT) is utilized to provide the proposed hybrid numerical-analytical solution . (author)

  9. A two-dimensional model for the analysis of radioactive waste contamination in soils: the integral transform method

    Energy Technology Data Exchange (ETDEWEB)

    Leal, M.A.; Ruperti Junior, N.J. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil). Coordenacao de Rejeitos Radioativos; Cotta, R.M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Lab. de Transmissao e Tecnologia do Calor

    1997-12-31

    A two-dimensional model for the flow and mass transfer of radioactive waste in porous media is investigated. The flow equations are modeled under steady-state Darcy regime assumptions, subjected to discrete boundary source terms. The mass transfer of the contaminant is modeled through the transient convection-diffusion equation, allowing for variable dispersivity coefficients and boundary source functions. The Generalized Integral Transform Technique (GITT) is utilized to provide the proposed hybrid numerical-analytical solution . (author) 12 refs., 3 figs.

  10. Behavioral Observation and Microbiological Analysis of Older Adult Consumers' Cross-Contamination Practices in a Model Domestic Kitchen.

    Science.gov (United States)

    Evans, Ellen W; Redmond, Elizabeth C

    2018-04-01

    The incidence of foodborne illness is higher in older adults because of their increased susceptibility; therefore, food safety practices are important. However, inadequate knowledge and negative attitudes toward food safety have been reported, which may increase use of unsafe food handling practices. Data on the actual food safety behaviors of older adults are lacking. In this study, food safety practices of older adults were observed and linked to microbiological analysis of kitchen surfaces to identify suspected routes of contamination. Older adults (≥60 years, n = 100) prepared a set meal in a model domestic kitchen sanitized according to a validated protocol to ensure minimal and consistent microbiological loads. Food safety behaviors were observed using ceiling-mounted cameras and recorded using a predetermined behavioral checklist. Surface microbiological contamination also was determined after food preparation. Overall, older adults frequently implemented unsafe food handling practices; 90% failed to implement adequate hand decontamination immediately after handling raw chicken. For older adults who used a larger number of adequate hand decontamination attempts, microbiological contamination levels in the kitchen following the food preparation session were significantly lower ( P food handling practices as suspected routes of microbiological cross-contamination in a model domestic kitchen. Findings indicate the potential impact on domestic food safety of unsafe food handling practices used by older adult consumers. This innovative approach revealed that a large proportion of older adults implement behaviors resulting in microbiological cross-contamination that may increase the risk of foodborne illness in the home.

  11. Post-mining water treatment. Nanofiltration of uranium-contaminated drainage. Experiments and modeling

    International Nuclear Information System (INIS)

    Hoyer, Michael

    2017-01-01

    Nanofiltration of real uranium-contaminated mine drainage was successfully discussed in experiments and modeling. For the simulation a renowned model was adapted that is capable of describing multi-component solutions. Although the description of synthetic multi-component solutions with a limited number of components was performed before ([Garcia-Aleman2004], [Geraldes2006], [Bandini2003]) the results of this work show that the adapted model is capable of describing the very complex solution. The model developed here is based on: The Donnan-Steric Partitioning Pore Model incorporating Dielectric Exclusion - DSPM and DE ref. [Bowen1997], [Bandini2003], [Bowen2002], [Vezzani2002]. The steric, electric, and dielectric exclusion model - SEDE ref. [Szymczyk2005]. The developed modeling approach is capable of describing multi-component transport, and is based on the pore radius, membrane thickness, and volumetric membrane charge density as physically relevant membrane parameters instead of mere fitting parameters which allows conclusions concerning membrane modification or process design. The experiments involve typical commercially available membranes in combination with a water sample of industrial relevance in the mining sector. Furthermore, it has been shown experimentally that uranium speciation influences its retention. Hence, all experiments consider the speciation of uranium when assessing its charge and size. In the simulation 10 different ionic components have been taken into account. By freely fitting 4 parameters in parallel (pore radius, membrane thickness, membrane charge, relative permittivity of the oriented water layer at the pore wall) an excellent agreement between experiment and simulation was obtained. Moreover, the determined membrane thickness and pore radius is in close agreement with the values obtained by independent membrane characterization using pure water permeability and glucose retention. On the other hand, the fitted and the literature

  12. Post-mining water treatment. Nanofiltration of uranium-contaminated drainage. Experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, Michael

    2017-07-01

    Nanofiltration of real uranium-contaminated mine drainage was successfully discussed in experiments and modeling. For the simulation a renowned model was adapted that is capable of describing multi-component solutions. Although the description of synthetic multi-component solutions with a limited number of components was performed before ([Garcia-Aleman2004], [Geraldes2006], [Bandini2003]) the results of this work show that the adapted model is capable of describing the very complex solution. The model developed here is based on: The Donnan-Steric Partitioning Pore Model incorporating Dielectric Exclusion - DSPM and DE ref. [Bowen1997], [Bandini2003], [Bowen2002], [Vezzani2002]. The steric, electric, and dielectric exclusion model - SEDE ref. [Szymczyk2005]. The developed modeling approach is capable of describing multi-component transport, and is based on the pore radius, membrane thickness, and volumetric membrane charge density as physically relevant membrane parameters instead of mere fitting parameters which allows conclusions concerning membrane modification or process design. The experiments involve typical commercially available membranes in combination with a water sample of industrial relevance in the mining sector. Furthermore, it has been shown experimentally that uranium speciation influences its retention. Hence, all experiments consider the speciation of uranium when assessing its charge and size. In the simulation 10 different ionic components have been taken into account. By freely fitting 4 parameters in parallel (pore radius, membrane thickness, membrane charge, relative permittivity of the oriented water layer at the pore wall) an excellent agreement between experiment and simulation was obtained. Moreover, the determined membrane thickness and pore radius is in close agreement with the values obtained by independent membrane characterization using pure water permeability and glucose retention. On the other hand, the fitted and the literature

  13. Validation of radiological efficiency model applied for the crops/soils contaminated by radiocaesium

    International Nuclear Information System (INIS)

    Montero, M.; Vazquez, C.; Moraleda, M.; Claver, F.

    2000-01-01

    The differences shown in the radiological efficiency applying the same agrochemical interventions on a range of contaminated agricultural scenarios by long-live radionuclides have conducted the radioecological studies to quantify the influence of local characteristics on the soil-to-plant transference. In the framework of the Decision Support Systems for post-accidental environmental restoration, a semi-mechanistic approach has been developed to estimate the soil-to-plant transfer factor from the major properties underlying the bioavailability of radiocaesium in soils and the absorption capacity by the crop. The model describes, for each soil texture class, the effects of time and K status on the transference of radiocaesium to plants. The approach lets to estimate the actual and the available minimum transference and to calculate the optimum amendment warranting the maximum radiological efficiency on an specific soil-crop combination. The parameterization and validation of the model from a database providing information about experimental transference studies for a collection of soil-crop combinations are shown. (Author) 4 refs

  14. Forecasts of agricultural exchanges with a view to a contamination model - the case of wheat in France

    International Nuclear Information System (INIS)

    Maccia, Carlo; Stemmelen, Eric; Pages, Pierre; Maitre, Paul

    1977-12-01

    Following a qualitative and quantitative analysis of the main data, two types of models were experimented allowing to 'project' exchange tables in a near future: 'empirical' models derived from a systematic study of the various coefficients able to specify the structure of an exchange matrix; 'explanatory' models based on the utilization of a linear model and the construction of a 'generalized cost' of exchange with the help of physical and economical parameters. The contamination model is then presented; it gives and forecasts individual and collective doses likely to be received by the inhabitants of each region from the ingestion of bread, biscuits... The doses are dependent on the results or assumptions at the level of the initial contaminations, the technical transformations of the product and the inter-regional exchanges of the initial product and its derivatives [fr

  15. Evaluation of a cross contamination model describing transfer of Salmonella spp. and Listeria monocytogenes during grinding of pork and beef

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Sant'Ana, A.S.; Hansen, Solvej Katrine Holm

    2016-01-01

    A cross contamination model was challenged and evaluated applying a new approach.•QMRA and Total Transfer Potential (TTP) were included.•Transfer estimates were not applicable for unlike processing.•The risk of disease may be reduced when using a stainless steel grinder.•Well-sharpened knife, and...

  16. Predicting soil, water and air concentrations of environmental contaminants locally and regionally; multimedia transport and transformation models

    International Nuclear Information System (INIS)

    McKone, T.E.; Daniels, J.I.

    1991-01-01

    Environmental scientists recognize that the environment functions as a complex, interconnected system. A realistic risk-management strategy for many contaminants requires a comprehensive and integrated assessment of local and regional transport and transformation processes. In response to this need, we have developed multimedia models that simulate the movement and transformation of chemicals as they spread through air, water, biota, soils, sediments, surface water and ground water. Each component of the environment is treated as a homogeneous subsystem that can exchange water, nutrients, and chemical contaminants with other adjacent compartments. In this paper, we illustrate the use of multimedia models and measurements as tools for screening the potential risks of contaminants released to air and deposited onto soil and plants. The contaminant list includes the volatile organic compounds (VOCs) tetrachloroethylene (PCE) and trichloroethylene (TCE), the semi-volatile organic compound benzo(a)pyrene, and the radionuclides tritium and uranium-238. We examine how chemical properties effect both the ultimate route and quantity of human and ecosystem contact and identify sensitivities and uncertainties in the model results. We consider the advantages of multimedia models relative to environmental monitoring data. (au)

  17. Bank of models for estimation of radioactive contamination consequences at the places where nuclear submarines are awaiting decommissioning

    International Nuclear Information System (INIS)

    Vorobiev, V.; Nosov, A.; Hitrikov, V.; Kiselev, V.; Korjov, M.; Krylov, A.; Kanevsky, M.; Petuhov, Y.

    1995-01-01

    The present paper presents a description of a computer bank of models for estimation of reactor accident consequences in harbors where Russian nuclear submarines are awaiting decommissioning. The computer bank is intended for an estimation of the consequences of a possible contamination of the surface water. It will also support the decision making in a tense situation. 2 figs., 1 tab

  18. Flow and contaminant transport in an airliner cabin induced by a moving body: Model experiments and CFD predictions

    Science.gov (United States)

    Poussou, Stephane B.; Mazumdar, Sagnik; Plesniak, Michael W.; Sojka, Paul E.; Chen, Qingyan

    2010-08-01

    The effects of a moving human body on flow and contaminant transport inside an aircraft cabin were investigated. Experiments were performed in a one-tenth scale, water-based model. The flow field and contaminant transport were measured using the Particle Image Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF) techniques, respectively. Measurements were obtained with (ventilation case) and without (baseline case) the cabin environmental control system (ECS). The PIV measurements show strong intermittency in the instantaneous near-wake flow. A symmetric downwash flow was observed along the vertical centerline of the moving body in the baseline case. The evolution of this flow pattern is profoundly perturbed by the flow from the ECS. Furthermore, a contaminant originating from the moving body is observed to convect to higher vertical locations in the presence of ventilation. These experimental data were used to validate a Computational Fluid Dynamic (CFD) model. The CFD model can effectively capture the characteristic flow features and contaminant transport observed in the small-scale model.

  19. Modelling cadmium contamination in paddy soils under long-term remediation measures: Model development and stochastic simulations.

    Science.gov (United States)

    Peng, Chi; Wang, Meie; Chen, Weiping

    2016-09-01

    A pollutant accumulation model (PAM) based on the mass balance theory was developed to simulate long-term changes of heavy metal concentrations in soil. When combined with Monte Carlo simulation, the model can predict the probability distributions of heavy metals in a soil-water-plant system with fluctuating environmental parameters and inputs from multiple pathways. The model was used for evaluating different remediation measures to deal with Cd contamination of paddy soils in Youxian county (Hunan province), China, under five scenarios, namely the default scenario (A), not returning paddy straw to the soil (B), reducing the deposition of Cd (C), liming (D), and integrating several remediation measures (E). The model predicted that the Cd contents of soil can lowered significantly by (B) and those of the plants by (D). However, in the long run, (D) will increase soil Cd. The concentrations of Cd in both soils and rice grains can be effectively reduced by (E), although it will take decades of effort. The history of Cd pollution and the major causes of Cd accumulation in soil were studied by means of sensitivity analysis and retrospective simulation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Modelling approach to limit aflatoxin B1 contamination in dairy cattle compound feed

    NARCIS (Netherlands)

    Bouzembrak, Y.; Fels-Klerx, van der H.J.

    2016-01-01

    Feeding dairy cattle with safe compound feed helps farmers to ensure food safety. However, several ingredients often used in compound feed production can be contaminated with aflatoxin B1 (AFB1), which may result into milk contaminated with aflatoxin M1. Given the number of ingredients and their

  1. Bayesian modeling approach for characterizing groundwater arsenic contamination in the Mekong River basin.

    Science.gov (United States)

    Cha, YoonKyung; Kim, Young Mo; Choi, Jae-Woo; Sthiannopkao, Suthipong; Cho, Kyung Hwa

    2016-01-01

    In the Mekong River basin, groundwater from tube-wells is a major drinking water source. However, arsenic (As) contamination in groundwater resources has become a critical issue in the watershed. In this study, As species such as total As (AsTOT), As(III), and As(V), were monitored across the watershed to investigate their characteristics and inter-relationships with water quality parameters, including pH and redox potential (Eh). The data illustrated a dramatic change in the relationship between AsTOT and Eh over a specific Eh range, suggesting the importance of Eh in predicting AsTOT. Thus, a Bayesian change-point model was developed to predict AsTOT concentrations based on Eh and pH, to determine changes in the AsTOT-Eh relationship. The model captured the Eh change-point (∼-100±15mV), which was compatible with the data. Importantly, the inclusion of this change-point in the model resulted in improved model fit and prediction accuracy; AsTOT concentrations were strongly negatively related to Eh values higher than the change-point. The process underlying this relationship was subsequently posited to be the reductive dissolution of mineral oxides and As release. Overall, AsTOT showed a weak positive relationship with Eh at a lower range, similar to those commonly observed in the Mekong River basin delta. It is expected that these results would serve as a guide for establishing public health strategies in the Mekong River Basin. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Hydrodynamic modelling of recreational water quality using Escherichia coli as an indicator of microbial contamination

    Science.gov (United States)

    Eregno, Fasil Ejigu; Tryland, Ingun; Tjomsland, Torulv; Kempa, Magdalena; Heistad, Arve

    2018-06-01

    Microbial contamination of recreational beaches is often at its worst after heavy rainfall events due to storm floods that carry fecal matter and other pollutants from the watershed. Similarly, overflows of untreated sewage from combined sewerage systems may discharge directly into coastal water or via rivers and streams. In order to understand the effect of rainfall events, wind-directions and tides on the recreational water quality, GEMSS, an integrated 3D hydrodynamic model was applied to assess the spreading of Escherichia coli (E. coli) at the Sandvika beaches, located in the Oslo fjord. The model was also used to theoretically investigate the effect of discharges from septic tanks from boats on the water quality at local beaches. The model make use of microbial decay rate as the main input representing the survival of microbial pathogens in the ocean, which vary widely depending on the type of pathogen and environmental stress. The predicted beach water quality was validated against observed data after a heavy rainfall event using Nash-Sutcliffe coefficient (E) and the overall result indicated that the model performed quite well and the simulation was in - good agreement with the observed E. coli concentrations for all beaches. The result of this study indicated that: 1) the bathing water quality was poor according to the EU bathing water directive up to two days after the heavy rainfall event depending on the location of the beach site. 2) The discharge from a boat at 300-meter distance to the beaches slightly increased the E. coli levels at the beaches. 3) The spreading of microbial pathogens from its source to the different beaches depended on the wind speed and the wind direction.

  3. SUDOQU: a new dose model to derive criteria for surface contamination of non-food (consumer) goods, containers and conveyances

    International Nuclear Information System (INIS)

    Van Dillen, Teun

    2015-01-01

    The Fukushima nuclear accident (Japan, 11 March 2011) revealed the need for well-founded criteria for surface contamination and associated screening levels related to the import of non-food (consumer) goods, containers and conveyances. The only available European-harmonised criteria are those laid down in the IAEA transport regulations, but these criteria date back from the early 1960's and only apply to the safe transport of radioactive materials. The main problem is that a generic dose-assessment model for consumer products is missing. Therefore, RIVM (National Institute for Public Health and the Environment) developed a new methodology entitled SUDOQU (Surface Dose Quantification) to calculate the annual effective dose for both consumers and non-radiological workers, addressing issues of removability of surface contamination. The methodology can be used to derive criteria and screening levels for surface contamination and could serve as a useful tool for policy-makers and radiation-protection specialists. (authors)

  4. A novel modeling tool with multi-stressor functionality for organic contaminant transport and fate in the Baltic Sea

    Energy Technology Data Exchange (ETDEWEB)

    Undeman, E., E-mail: emma.undeman@itm.su.se [Baltic Nest Institute, Baltic Sea Centre, Stockholm University, 10691 Stockholm (Sweden); Department of Applied Environmental Science, Stockholm University, 11418 Stockholm (Sweden); Gustafsson, E., E-mail: erik.gustafsson@su.se [Baltic Nest Institute, Baltic Sea Centre, Stockholm University, 10691 Stockholm (Sweden); Gustafsson, B.G., E-mail: bo.gustafsson@su.se [Baltic Nest Institute, Baltic Sea Centre, Stockholm University, 10691 Stockholm (Sweden)

    2014-11-01

    The coupled physical–biogeochemical model BALTSEM, previously used to assess nutrient/carbon cycles and eutrophication in the Baltic Sea, has been expanded to include algorithms for calculations of organic contaminant environmental transport and fate. This novel model version (BALTSEM-POP) is evaluated for polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and hexachlorobenzene (HCB) in Baltic Sea surface water and sediment. Modeled dissolved concentrations are usually within a factor of 2–4 of observed concentrations, however with larger deviations for furans. Calculated concentrations in particulate organic matter are less accurate (within factors of 1–700), likely due to errors in estimated pelagic biomass, particulate matter–water partitioning, and large natural variability in field data. Concentrations in sediments are usually predicted within a factor of 6. The good performance of the model illustrates its usefulness for exploration of contaminant fate in response to variations in nutrient input and climatic conditions in the Baltic Sea marine environment. - Highlights: • A new model for organic chemical transport and fate in the Baltic Sea is presented. • Physical and biogeochemical processes are linked to organic contaminant transport. • The model is evaluated for PCBs, HCB and PCDD/Fs. • The model can predict dissolved concentrations within a factor of ca 2–4. • Predictions for concentrations in particulate matter and sediment are less accurate.

  5. Predicting soil, water, and air concentrations of environmental contaminants locally and regionally: Multimedia transport and transformation models

    International Nuclear Information System (INIS)

    McKone, T.E.; Daniels, J.I.

    1991-10-01

    Environmental scientists recognize that the environment functions as a complex, interconnected system. A realistic risk-management strategy for many contaminants requires a comprehensive and integrated assessment of local and regional transport and transformation processes. In response to this need, we have developed multimedia models that simulate the movement and transformation of chemicals as they spread through air, water, biota, soils, sediments, surface water, and ground water. Each component of the environment is treated as a homogeneous subsystem that can exchange water, nutrients, and chemical contaminants with other adjacent compartments. In this paper, we illustrate the use of multimedia models and measurements as tools for screening the potential risks of contaminants released to air and deposited onto soil and plants. The contaminant list includes the volatile organic compounds (VOCs) tetrachloroethylene (PCE) and trichloroethylene (TCE), the semi-volatile organic compound benzo(a)pyrene, and the radionuclides tritium and uranium-238. We examine how chemical properties effect both the ultimate route and quantity of human and ecosystem contact and identify sensitivities and uncertainties in the model results

  6. RAGBEEF: a FORTRAN IV implementation of a time-dependent model for radionuclide contamination of beef

    Energy Technology Data Exchange (ETDEWEB)

    Pleasant, J C; McDowell-Boyer, L M; Killough, G G

    1982-06-01

    RAGBEEF is a FORTRAN IV program that calculates radionuclide concentrations in beef as a result of ingestion of contaminated feeds, pasture, and pasture soil by beef cattle. The model implemented by RAGBEEF is dynamic in nature, allowing the user to consider age- and season-dependent aspects of beef cattle management in estimating concentrations in beef. It serves as an auxiliary code to RAGTIME, previously documented by the authors, which calculates radionuclide concentrations in agricultural crops in a dynamic manner, but evaluates concentrations in beef for steady-state conditions only. The time-dependent concentrations in feeds, pasture, and pasture soil generated by RAGTIME are used as input to the RAGBEEF code. RAGBEEF, as presently implemented, calculates radionuclide concentrations in the muscle of age-based cohorts in a beef cattle herd. Concentrations in the milk of lactating cows are also calculated, but are assumed age-dependent as in RAGTIME. Radionuclide concentrations in beef and milk are described in RAGBEEF by a system of ordinary linear differential equations in which the transfer rate of radioactivity between compartments is proportional to the inventory of radioactivity in the source compartment. This system is solved by use of the GEAR package for solution of systems of ordinary differential equations. The accuracy of this solution is monitored at various check points by comparison with explicit solutions of Bateman-type equations. This report describes the age- and season-dependent considerations making up the RAGBEEF model, as well as presenting the equations which describe the model and a documentation of the associated computer code. Listings of the RAGBEEF and updated RAGTIME codes are provided in appendices, as are the results of a sample run of RAGBEEF and a description of recent modifications to RAGTIME.

  7. Risk assessment through drinking water pathway via uncertainty modeling of contaminant transport using soft computing

    International Nuclear Information System (INIS)

    Datta, D.; Ranade, A.K.; Pandey, M.; Sathyabama, N.; Kumar, Brij

    2012-01-01

    The basic objective of an environmental impact assessment (EIA) is to build guidelines to reduce the associated risk or mitigate the consequences of the reactor accident at its source to prevent deterministic health effects, to reduce the risk of stochastic health effects (eg. cancer and severe hereditary effects) as much as reasonable achievable by implementing protective actions in accordance with IAEA guidance (IAEA Safety Series No. 115, 1996). The measure of exposure being the basic tool to take any appropriate decisions related to risk reduction, EIA is traditionally expressed in terms of radiation exposure to the member of the public. However, models used to estimate the exposure received by the member of the public are governed by parameters some of which are deterministic with relative uncertainty and some of which are stochastic as well as imprecise (insufficient knowledge). In an admixture environment of this type, it is essential to assess the uncertainty of a model to estimate the bounds of the exposure to the public to invoke a decision during an event of nuclear or radiological emergency. With a view to this soft computing technique such as evidence theory based assessment of model parameters is addressed to compute the risk or exposure to the member of the public. The possible pathway of exposure to the member of the public in the aquatic food stream is the drinking of water. Accordingly, this paper presents the uncertainty analysis of exposure via uncertainty analysis of the contaminated water. Evidence theory finally addresses the uncertainty in terms of lower bound as belief measure and upper bound of exposure as plausibility measure. In this work EIA is presented using evidence theory. Data fusion technique is used to aggregate the knowledge on the uncertain information. Uncertainty of concentration and exposure is expressed as an interval of belief, plausibility

  8. Development and testing of a compartmentalized reaction network model for redox zones in contaminated aquifers

    Science.gov (United States)

    Abrams , Robert H.; Loague, Keith; Kent, Douglas B.

    1998-01-01

    The work reported here is the first part of a larger effort focused on efficient numerical simulation of redox zone development in contaminated aquifers. The sequential use of various electron acceptors, which is governed by the energy yield of each reaction, gives rise to redox zones. The large difference in energy yields between the various redox reactions leads to systems of equations that are extremely ill-conditioned. These equations are very difficult to solve, especially in the context of coupled fluid flow, solute transport, and geochemical simulations. We have developed a general, rational method to solve such systems where we focus on the dominant reactions, compartmentalizing them in a manner that is analogous to the redox zones that are often observed in the field. The compartmentalized approach allows us to easily solve a complex geochemical system as a function of time and energy yield, laying the foundation for our ongoing work in which we couple the reaction network, for the development of redox zones, to a model of subsurface fluid flow and solute transport. Our method (1) solves the numerical system without evoking a redox parameter, (2) improves the numerical stability of redox systems by choosing which compartment and thus which reaction network to use based upon the concentration ratios of key constituents, (3) simulates the development of redox zones as a function of time without the use of inhibition factors or switching functions, and (4) can reduce the number of transport equations that need to be solved in space and time. We show through the use of various model performance evaluation statistics that the appropriate compartment choice under different geochemical conditions leads to numerical solutions without significant error. The compartmentalized approach described here facilitates the next phase of this effort where we couple the redox zone reaction network to models of fluid flow and solute transport.

  9. RAGBEEF: a FORTRAN IV implementation of a time-dependent model for radionuclide contamination of beef

    International Nuclear Information System (INIS)

    Pleasant, J.C.; McDowell-Boyer, L.M; Killough, G.G.

    1982-06-01

    RAGBEEF is a FORTRAN IV program that calculates radionuclide concentrations in beef as a result of ingestion of contaminated feeds, pasture, and pasture soil by beef cattle. The model implemented by RAGBEEF is dynamic in nature, allowing the user to consider age- and season-dependent aspects of beef cattle management in estimating concentrations in beef. It serves as an auxiliary code to RAGTIME, previously documented by the authors, which calculates radionuclide concentrations in agricultural crops in a dynamic manner, but evaluates concentrations in beef for steady-state conditions only. The time-dependent concentrations in feeds, pasture, and pasture soil generated by RAGTIME are used as input to the RAGBEEF code. RAGBEEF, as presently implemented, calculates radionuclide concentrations in the muscle of age-based cohorts in a beef cattle herd. Concentrations in the milk of lactating cows are also calculated, but are assumed age-dependent as in RAGTIME. Radionuclide concentrations in beef and milk are described in RAGBEEF by a system of ordinary linear differential equations in which the transfer rate of radioactivity between compartments is proportional to the inventory of radioactivity in the source compartment. This system is solved by use of the GEAR package for solution of systems of ordinary differential equations. The accuracy of this solution is monitored at various check points by comparison with explicit solutions of Bateman-type equations. This report describes the age- and season-dependent considerations making up the RAGBEEF model, as well as presenting the equations which describe the model and a documentation of the associated computer code. Listings of the RAGBEEF and updated RAGTIME codes are provided in appendices, as are the results of a sample run of RAGBEEF and a description of recent modifications to RAGTIME

  10. The food processing contaminant glyoxal promotes tumour growth in the multiple intestinal neoplasia (Min) mouse model.

    Science.gov (United States)

    Svendsen, Camilla; Høie, Anja Hortemo; Alexander, Jan; Murkovic, Michael; Husøy, Trine

    2016-08-01

    Glyoxal is formed endogenously and at a higher rate in the case of hyperglycemia. Glyoxal is also a food processing contaminant and has been shown to be mutagenic and genotoxic in vitro. The tumourigenic potential of glyoxal was investigated using the multiple intestinal neoplasia (Min) mouse model, which spontaneously develops intestinal tumours and is susceptible to intestinal carcinogens. C57BL/6J females were mated with Min males. Four days after mating and throughout gestation and lactation, the pregnant dams were exposed to glyoxal through drinking water (0.0125%, 0.025%, 0.05%, 0.1%) or regular tap water. Female and male offspring were housed separately from PND21 and continued with the same treatment. One group were only exposed to 0.1% glyoxal from postnatal day (PND) 21. There was no difference in the number of intestinal tumours between control and treatment groups. However, exposure to 0.1% glyoxal starting in utero and at PND21 caused a significant increase in tumour size in the small intestine for male and female mice in comparison with respective control groups. This study suggests that glyoxal has tumour growth promoting properties in the small intestine in Min mice. Copyright © 2016 Norwegian Institute of Public Health. Published by Elsevier Ltd.. All rights reserved.

  11. Pathway analysis and exposure assessment: MEPAS modeling for nonradiological chemical contaminants at the Hanford Site

    International Nuclear Information System (INIS)

    Blanton, M.L.; Dirkes, R.; Buck, J.; Cooper, A.; Castieton, K.; Glantz, C.

    1995-01-01

    A Chemical Pathway Analysis and Exposure Assessment was performed by the Surface Environmental Surveillance Project (SESP). The SESP monitors air, surface water, sediment, agricultural products, vegetation, soil, and wildlife in order to assess onsite of offsite environmental impacts and offsite human health risk at the Hanford Site. The objectives of this study are (1) determine if a nonradiological chemical monitoring program is warranted for the Hanford Site, (2) ensure that the selection of surveillance parameters such as media, sampling location, and analytes are chosen in a manner that is scientifically sound and cost-efficient, and (3) identify specific nonradiological chemicals of concern (COC) for the Hanford Site. The basis for identification of COC for the Hanford Site was an extensive literature review. The model was also used to predict COC concentrations required onsite to achieve an offsite cancer incidence of 1 E-6 and a hazard quotient of 1.0. This study indicated that nonradiological chemical contamination occurring onsite does not pose a significant offsite human health risk. The highest cancer incidence to the offsite maximally exposed individual from COC was from arsenic (1.76E-1 0); the highest hazard quotient was chromium VI (1.48E-04)

  12. Experimental Model of Contaminant Transport by a Moving Wake Inside an Aircraft Cabin

    Science.gov (United States)

    Poussou, Stephane; Sojka, Paul; Plesniak, Michael

    2008-11-01

    The air cabin environment in jetliners is designed to provide comfortable and healthy conditions for passengers. The air ventilation system produces a recirculating pattern designed to minimize secondary flow between seat rows. However, disturbances are frequently introduced by individuals walking along the aisle and may significantly modify air distribution and quality. Spreading of infectious aerosols or biochemical agents presents potential health hazards. A fundamental study has been undertaken to understand the unsteady transport phenomena, to validate numerical simulations and to improve air monitoring systems. A finite moving body is modeled experimentally in a 10:1 scale simplified aircraft cabin equipped with ventilation, at a Reynolds number (based on body height) of the order of 10,000. Measurements of the ventilation and wake velocity fields are obtained using PIV and PLIF. Results indicate that the evolution of the typical downwash behind the body is profoundly perturbed by the ventilation flow. Furthermore, the interaction between wake and ventilation flow significantly alters scalar contaminant migration.

  13. Chaotic-Dynamical Conceptual Model to Describe Fluid Flow and Contaminant Transport in a Fractured Vadose Zone

    International Nuclear Information System (INIS)

    Faybishenko, Boris; Doughty, Christine; Geller, Jil T.

    1999-01-01

    DOE faces the remediation of numerous contaminated sites, such as those at Hanford, INEEL, LLNL, and LBNL, where organic and/or radioactive wastes were intentionally or accidentally released to the vadose zone from surface spills, underground tanks, cribs, shallow ponds, and deep wells. Migration of these contaminants through the vadose zone has led to the contamination of (or threatens to contaminate) underlying groundwater. A key issue in choosing a corrective action plan to clean up contaminated sites is the determination of the location, total mass, mobility and travel time to receptors for contaminants moving in the vadose zone. These problems are difficult to solve in a technically defensible and accurate manner because contaminants travel downward intermittently, through narrow pathways, driven by variations in environmental conditions. These preferential flow pathways can be difficult to find and predict. The primary objective of this project is to determine if and when dynamical chaos theory can be used to investigate infiltration of fluid and contaminant transport in heterogeneous soils and fractured rocks. The objective of this project is being achieved through the following activities: Development of multi scale conceptual models and mathematical and numerical algorithms for flow and transport, which incorporate both (a) the spatial variability of heterogeneous porous and fractured media and (b) the temporal dynamics of flow and transport; Development of appropriate experimental field and laboratory techniques needed to detect diagnostic parameters for chaotic behavior of flow; Evaluation of chaotic behavior of flow in laboratory and field experiments using methods from non-linear dynamics; Evaluation of the impact these dynamics may have on contaminant transport through heterogeneous fractured rocks and soils and remediation efforts. This approach is based on the consideration of multi scale spatial heterogeneity and flow phenomena that are affected by

  14. Characterization of chemical contaminants generated by a desktop fused deposition modeling 3-dimensional Printer.

    Science.gov (United States)

    Stefaniak, Aleksandr B; LeBouf, Ryan F; Yi, Jinghai; Ham, Jason; Nurkewicz, Timothy; Schwegler-Berry, Diane E; Chen, Bean T; Wells, J Raymond; Duling, Matthew G; Lawrence, Robert B; Martin, Stephen B; Johnson, Alyson R; Virji, M Abbas

    2017-07-01

    Printing devices are known to emit chemicals into the indoor atmosphere. Understanding factors that influence release of chemical contaminants from printers is necessary to develop effective exposure assessment and control strategies. In this study, a desktop fused deposition modeling (FDM) 3-dimensional (3-D) printer using acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) filaments and two monochrome laser printers were evaluated in a 0.5 m 3 chamber. During printing, chamber air was monitored for vapors using a real-time photoionization detector (results expressed as isobutylene equivalents) to measure total volatile organic compound (TVOC) concentrations, evacuated canisters to identify specific VOCs by off-line gas chromatography-mass spectrometry (GC-MS) analysis, and liquid bubblers to identify carbonyl compounds by GC-MS. Airborne particles were collected on filters for off-line analysis using scanning electron microscopy with an energy dispersive x-ray detector to identify elemental constituents. For 3-D printing, TVOC emission rates were influenced by a printer malfunction, filament type, and to a lesser extent, by filament color; however, rates were not influenced by the number of printer nozzles used or the manufacturer's provided cover. TVOC emission rates were significantly lower for the 3-D printer (49-3552 µg h -1 ) compared to the laser printers (5782-7735 µg h -1 ). A total of 14 VOCs were identified during 3-D printing that were not present during laser printing. 3-D printed objects continued to off-gas styrene, indicating potential for continued exposure after the print job is completed. Carbonyl reaction products were likely formed from emissions of the 3-D printer, including 4-oxopentanal. Ultrafine particles generated by the 3-D printer using ABS and a laser printer contained chromium. Consideration of the factors that influenced the release of chemical contaminants (including known and suspected asthmagens such as styrene and

  15. Peri-operative Blood Transfusion in open Suprapubic Transvesical ...

    African Journals Online (AJOL)

    INTRODUCTION: Open simple prostatectomy is the most effective and the most durable method of controlling symptoms associated with benign prostatic hyperplasia, especially in sub- Saharan Africa, where TURP set and expertise are unavailable in most health institutions. The risk of perioperative heterologous blood ...

  16. Predictors of peri-operative risk acceptance by South African ...

    African Journals Online (AJOL)

    Patients must balance the considerations in favour of surgery with those favouring .... Carotid artery disease and peripheral vascular disease. 4 (6.7%). Infra-renal ..... pain? the impact of current pain on decisions about future dental treatments.

  17. A practical approach to managing diabetes in the peri- operative ...

    African Journals Online (AJOL)

    This article focuses on perioperative diabetes management of ... Federation reports that there are currently ~1.8 million adults in ... In South Africa (SA), it is estimated that ... In this review, the authors discuss DM within the SA context. .... glucose; ICU = intensive care unit; VRIII = variable rate intravenous insulin infusion.

  18. Anaesthesia and peri-operative care for laparoscopic donor nephrectomy

    NARCIS (Netherlands)

    I.R.A.M. Mertens Zur Borg (Ingrid)

    2008-01-01

    textabstractA successful renal transplant for patients with kidney failure reduces mortality rate when compared to patients who continue dialysis. Organ donation from living donors has significant better results over organ donation from deceased donors. Traditionally the surgical

  19. Are lipophilic beta-blockers preferable for peri-operative ...

    African Journals Online (AJOL)

    There is therefore doubt whether atenolol is the correct cardioprotective drug in the surgical setting. It is possible that some of the physiochemical properties of atenolol (hydrophilic and cardioselective) may decrease it's efficacy in comparison to its more lipophilic congeners (such as propranolol, metoprolol, bisoprolol and ...

  20. Abnormal peri-operative haemorrhage in asymptomatic patients is ...

    African Journals Online (AJOL)

    Accordingly, we undertook two studies to detertnine whether it could be justified in patients without a history of abnormal bleeding. In the first of these, 45 of 159 patients were excluded because of aspirin ingestion and a further 3 because of positive bleeding history so that prothrombin time, activated partial thromboplastin ...

  1. Peri-operative management for excision of plexiform ...

    African Journals Online (AJOL)

    Case report: A 28-year-old female weighing 78 kilograms presented at the University of Port Harcourt Teaching Hospital (UPTH) with a huge left thigh mass, nodules and brownish skin patches (café-au-lait spots) all over her body. Plexiform neurofibromatosis was diagnosed. The mass was subsequently excised under ...

  2. Abnormal peri-operative haemorrhage in asymptomatic patients is ...

    African Journals Online (AJOL)

    history so that prothrotnbin titne, activated partial throtnboplastin titne, bleeding .... was used as a screen in 12 000 patients and was unable to identify the ... 1982; 117: 48-51. 2. Barber A, Green D, Galluzzo T, Chung-Hsin T. The bleeding time.

  3. Are lipophilic beta-blockers preferable for peri-operative ...

    African Journals Online (AJOL)

    Adele

    management of hypertension and post myocardial infarction.4-6. Are lipophilic ... studies in hypertensive medical patients showed no difference in cardiovascular ... atenolol and bendroflumethiazide arm.7 In meta-analyses of beta-blocker ...

  4. An Iterative Ensemble Kalman Filter with One-Step-Ahead Smoothing for State-Parameters Estimation of Contaminant Transport Models

    KAUST Repository

    Gharamti, M. E.

    2015-05-11

    The ensemble Kalman filter (EnKF) is a popular method for state-parameters estimation of subsurface flow and transport models based on field measurements. The common filtering procedure is to directly update the state and parameters as one single vector, which is known as the Joint-EnKF. In this study, we follow the one-step-ahead smoothing formulation of the filtering problem, to derive a new joint-based EnKF which involves a smoothing step of the state between two successive analysis steps. The new state-parameters estimation scheme is derived in a consistent Bayesian filtering framework and results in separate update steps for the state and the parameters. This new algorithm bears strong resemblance with the Dual-EnKF, but unlike the latter which first propagates the state with the model then updates it with the new observation, the proposed scheme starts by an update step, followed by a model integration step. We exploit this new formulation of the joint filtering problem and propose an efficient model-integration-free iterative procedure on the update step of the parameters only for further improved performances. Numerical experiments are conducted with a two-dimensional synthetic subsurface transport model simulating the migration of a contaminant plume in a heterogenous aquifer domain. Contaminant concentration data are assimilated to estimate both the contaminant state and the hydraulic conductivity field. Assimilation runs are performed under imperfect modeling conditions and various observational scenarios. Simulation results suggest that the proposed scheme efficiently recovers both the contaminant state and the aquifer conductivity, providing more accurate estimates than the standard Joint and Dual EnKFs in all tested scenarios. Iterating on the update step of the new scheme further enhances the proposed filter’s behavior. In term of computational cost, the new Joint-EnKF is almost equivalent to that of the Dual-EnKF, but requires twice more model

  5. Tracing contaminant pathways in sandy heterogeneous glaciofluvial sediments using a sedimentary depositional model

    International Nuclear Information System (INIS)

    Webb, E.K.; Anderson, M.P.

    1990-01-01

    Heterogeneous sedimentary deposits present complications for tracking contaminant movement by causing a complex advective flow field. Connected areas of high conductivity produce so-called fast paths that control movement of solutes. Identifying potential fast paths and describing the variation in hydraulic properties was attempted through simulating the deposition of a glaciofluvial deposit (outwash). Glaciofluvial deposits usually consist of several depositional facies, each of which has different physical characteristics, depositional structures and hydraulic properties. Therefore, it is unlikely that the property of stationarity (a constant mean hydraulic conductivity and a mono-modal probability distribution) holds for an entire glaciofluvial sequence. However, the process of dividing an outwash sequence into geologic facies presumably identifies units of material with similar physical characteristics. It is proposed that patterns of geologic facies determined by field observation can be quantified by mathematical simulation of sediment deposition. Subsequently, the simulated sediment distributions can be used to define the distribution of hydrogeologic parameters and locate possible fast paths. To test this hypothesis, a hypothetical glacial outwash deposit based on geologic facies descriptions contained in the literature was simulated using a sedimentary depositional model, SEDSIM, to produce a three-dimensional description of sediment grain size distributions. Grain size distributions were then used to estimate the spatial distribution of hydraulic conductivity. Subsequently a finite-difference flow model and linked particle tracking algorithm were used to trace conservative transport pathways. This represents a first step in describing the spatial heterogeneity of hydrogeologic characteristics for glaciofluvial and other braided stream environments. (Author) (39 refs., 7 figs.)

  6. Instrument evaluation no. 11. ESI nuclear model 271 C contamination monitor

    International Nuclear Information System (INIS)

    Burgess, P.H.; Iles, W.J.

    1978-06-01

    The various radiations encountered in radiological protection cover a wide range of energies and radiation measurements have to he carried out under an equally broad spectrum of environmental conditions. This report is one of a series intended to give information on the performance characteristics of radiological protection instruments, to assist in the selection of appropriate instruments for a given purpose, to interpret the results obtained with such instruments, and, in particular, to know the likely sources and magnitude of errors that might be associated with measurements in the field. The radiation, electrical and environmental characteristics of radiation protection instruments are considered together with those aspects of the construction which make an instrument convenient for routine use. To provide consistent criteria for instrument performance, the range of tests performed on any particular class of instrument, the test methods and the criteria of acceptable performance are based broadly on the appropriate Recommendations of the International Electrotechnical Commission. The radiations in the tests are, in general, selected from the range of reference radiations for instrument calibration being drawn up by the International Standards Organisation. Normally, each report deals with the capabilities and limitations of one model of instrument and no direct comparison with other instruments intended for similar purposes is made, since the significance of particular performance characteristics largely depends on the radiations and environmental conditions in which the instrument is to be used. The results quoted here have all been obtained from tests on instruments in routine production, with the appropriate measurements being made by the NRPB. This report deals with the ESI Nuclear Model 271 C; a general purpose contamination monitor, comprising a GM tube connected by a coiled extensible cable to a ratemeter

  7. Modelling tools for integrating geological, geophysical and contamination data for characterization of groundwater plumes

    DEFF Research Database (Denmark)

    Balbarini, Nicola

    the contaminant plume in a shallow and a deep plume. These plumes have different chemical characteristics and different migration paths to the stream. This has implications for the risk assessment of the stream and groundwater in the area. The difficulty of determining groundwater flow paths means that it is also...... receptors, including streams. Key risk assessment parameters, such as contaminant mass discharge estimates, and tools are then used to evaluate the risk. The cost of drilling often makes investigations of large and/or deep contaminant plumes unfeasible. For this reason, it is important to develop cost...... organic compounds, including pharmaceutical compounds and chlorinated ethenes. The correlation between DCIP and organic compounds is indirect and depends on the chemical composition of the contaminant plume and the transport processes. Thus, the correlations are site specific and may change between...

  8. Assessment of immunotoxic effects of environmental contamination using a cotton rat model

    International Nuclear Information System (INIS)

    Zhang, Z.R.; Propst, T.L.; McMurry, S.T.; Lochmiller, R.L.; McBee, K.; Quails, C.W. Jr.; Burks, S.L.

    1993-01-01

    Adult National Institute of Health inbred cotton rats (Sigmodon hispidus) were housed in six terrestrial mesocosms on or near an abandoned oil refinery in central Oklahoma for 56 days. Exposure sites included three mesocosms located on sites judged to be contaminated with a variety of complex mixtures of contaminants and three matched reference mesocosm. In addition, wild cotton rats were collected from contaminated and reference areas near the mesocosm sites. Peripheral leukocyte and erythrocyte variables, secondary lymphoid organ weight and cellularity, proliferative response of splenocytes to mitogens, lymphocyte subpopulations, delayed-type hypersensitivity response, 24 h hypersensitivity, antibody response to keyhole limpet hemocyanin, NK cell activity, macrophage metabolic functions, and complement activity were measures as a comprehensive screen of immunocompetence. According to current data analysis, peripheral leukocyte numbers, mitogenic response of splenocytes, antibody response to keyhole limpet hemocyanin, delayed-type sensitivity and 24 h hypersensitivity were altered by contaminant exposure

  9. MOIRA models and methodologies for assessing the effectiveness of countermeasures in complex aquatic systems contaminated by radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Monte, L. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Brittain, J.E. [Oslo Univ., Oslo (Norway); Zoological Museum, Oslo (Norway); Haakanson, L. [Uppsala Univ., Uppsala (Sweden). Inst. of Earth Science; Gallego Diaz, E. [Madrid Univ. Politecnica, Madrid (Spain). Dept. de Ingenieria Nuclear

    1999-07-01

    The present report is composed of a set of articles written by the partners of the MOIRA project (a model-based computerized system for management support to identify optimal remedial strategies for restoring radionuclide contaminated aquatic ecosystems and drainage areas). The report describes models for predicting the behaviour of radionuclides in complex aquatic systems and the effects of countermeasures for their restoration. [Italian] Il rapporto contiene articoli preparati nell'ambito del progetto MOIRA (a model-based computerized system for management support to identify optimal remedial strategies for restoring radionuclide contaminated aquatic ecosystems and drainage areas), che descrive alcuni modelli per la previsione del comportamento di radionuclidi in sistemi acquatici complessi e per la valutazione dell'effetto delle contromisure per il loro recupero.

  10. MOIRA models and methodologies for assessing the effectiveness of countermeasures in complex aquatic systems contaminated by radionuclides

    Energy Technology Data Exchange (ETDEWEB)

    Monte, L [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente; Brittain, J E [Oslo Univ., Oslo (Norway); Zoological Museum, Oslo [Norway; Haakanson, L [Uppsala Univ., Uppsala (Sweden). Inst. of Earth Science; Gallego Diaz, E [Madrid Univ. Politecnica, Madrid (Spain). Dept. de Ingenieria Nuclear

    1999-07-01

    The present report is composed of a set of articles written by the partners of the MOIRA project (a model-based computerized system for management support to identify optimal remedial strategies for restoring radionuclide contaminated aquatic ecosystems and drainage areas). The report describes models for predicting the behaviour of radionuclides in complex aquatic systems and the effects of countermeasures for their restoration. [Italian] Il rapporto contiene articoli preparati nell'ambito del progetto MOIRA (a model-based computerized system for management support to identify optimal remedial strategies for restoring radionuclide contaminated aquatic ecosystems and drainage areas), che descrive alcuni modelli per la previsione del comportamento di radionuclidi in sistemi acquatici complessi e per la valutazione dell'effetto delle contromisure per il loro recupero.

  11. A multi-objective simulation-optimization model for in situ bioremediation of groundwater contamination: Application of bargaining theory

    Science.gov (United States)

    Raei, Ehsan; Nikoo, Mohammad Reza; Pourshahabi, Shokoufeh

    2017-08-01

    In the present study, a BIOPLUME III simulation model is coupled with a non-dominating sorting genetic algorithm (NSGA-II)-based model for optimal design of in situ groundwater bioremediation system, considering preferences of stakeholders. Ministry of Energy (MOE), Department of Environment (DOE), and National Disaster Management Organization (NDMO) are three stakeholders in the groundwater bioremediation problem in Iran. Based on the preferences of these stakeholders, the multi-objective optimization model tries to minimize: (1) cost; (2) sum of contaminant concentrations that violate standard; (3) contaminant plume fragmentation. The NSGA-II multi-objective optimization method gives Pareto-optimal solutions. A compromised solution is determined using fallback bargaining with impasse to achieve a consensus among the stakeholders. In this study, two different approaches are investigated and compared based on two different domains for locations of injection and extraction wells. At the first approach, a limited number of predefined locations is considered according to previous similar studies. At the second approach, all possible points in study area are investigated to find optimal locations, arrangement, and flow rate of injection and extraction wells. Involvement of the stakeholders, investigating all possible points instead of a limited number of locations for wells, and minimizing the contaminant plume fragmentation during bioremediation are new innovations in this research. Besides, the simulation period is divided into smaller time intervals for more efficient optimization. Image processing toolbox in MATLAB® software is utilized for calculation of the third objective function. In comparison with previous studies, cost is reduced using the proposed methodology. Dispersion of the contaminant plume is reduced in both presented approaches using the third objective function. Considering all possible points in the study area for determining the optimal locations

  12. Modeling the potential role of a forest ecosystem in phytostabilization and phytoextraction of 90Sr at a contaminated watershed

    International Nuclear Information System (INIS)

    Garten, C.T. Jr.

    1999-01-01

    The behavior of 90 Sr at forest sites in the White Oak Creek watershed, near Oak Ridge, Tennessee, was simulated with a simple, site-specific, multicompartment model that linked biomass and element cycling dynamics. The model was used to predict the role of forest cover in mitigating hydrologic losses of 90 Sr from contaminated soils (i.e. phytostabilization) under conditions where contaminant transport is governed mainly by shallow subsurface flow. The model was also used to predict the removal of 90 Sr from soil (i.e. phytoextraction) through the growth and harvest of short rotation woody crops over a period of 30 years. Simulations with the model indicated that (1) forest preservation on the watershed is a form of phytostabilization because forest cover helps to minimize hydrologic losses of 90 Sr and (2) an attempt to significantly reduce amounts of 90 Sr in soil through phytoextraction would be unsuccessful. Over a period of 30 years, and under various management strategies, the model predicted that 90 Sr initially present in soil at a contaminated site was lost through hydrologic transport and <53% was lost by radioactive decay. Phytostabilization may be important in the management of radioactive land when issues like waste minimization and pollution prevention affect the selection of technologies to be used in environmental restoration. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  13. Examination of the uncertainty in contaminant fate and transport modeling: a case study in the Venice Lagoon.

    Science.gov (United States)

    Sommerfreund, J; Arhonditsis, G B; Diamond, M L; Frignani, M; Capodaglio, G; Gerino, M; Bellucci, L; Giuliani, S; Mugnai, C

    2010-03-01

    A Monte Carlo analysis is used to quantify environmental parametric uncertainty in a multi-segment, multi-chemical model of the Venice Lagoon. Scientific knowledge, expert judgment and observational data are used to formulate prior probability distributions that characterize the uncertainty pertaining to 43 environmental system parameters. The propagation of this uncertainty through the model is then assessed by a comparative analysis of the moments (central tendency, dispersion) of the model output distributions. We also apply principal component analysis in combination with correlation analysis to identify the most influential parameters, thereby gaining mechanistic insights into the ecosystem functioning. We found that modeled concentrations of Cu, Pb, OCDD/F and PCB-180 varied by up to an order of magnitude, exhibiting both contaminant- and site-specific variability. These distributions generally overlapped with the measured concentration ranges. We also found that the uncertainty of the contaminant concentrations in the Venice Lagoon was characterized by two modes of spatial variability, mainly driven by the local hydrodynamic regime, which separate the northern and central parts of the lagoon and the more isolated southern basin. While spatial contaminant gradients in the lagoon were primarily shaped by hydrology, our analysis also shows that the interplay amongst the in-place historical pollution in the central lagoon, the local suspended sediment concentrations and the sediment burial rates exerts significant control on the variability of the contaminant concentrations. We conclude that the probabilistic analysis presented herein is valuable for quantifying uncertainty and probing its cause in over-parameterized models, while some of our results can be used to dictate where additional data collection efforts should focus on and the directions that future model refinement should follow. (c) 2009 Elsevier Inc. All rights reserved.

  14. Applicability of the Linear Sorption Isotherm Model to Represent Contaminant Transport Processes in Site Wide Performance Assessments

    International Nuclear Information System (INIS)

    FOGWELL, T.W.; LAST, G.V.

    2003-01-01

    The estimation of flux of contaminants through the vadose zone to the groundwater under varying geologic, hydrologic, and chemical conditions is key to making technically credible and sound decisions regarding soil site characterization and remediation, single-shell tank retrieval, and waste site closures (DOE 2000). One of the principal needs identified in the science and technology roadmap (DOE 2000) is the need to improve the conceptual and numerical models that describe the location of contaminants today, and to provide the basis for forecasting future movement of contaminants on both site-specific and site-wide scales. The State of Knowledge (DOE 1999) and Preliminary Concepts documents describe the importance of geochemical processes on the transport of contaminants through the Vadose Zone. These processes have been identified in the international list of Features, Events, and Processes (FEPs) (NEA 2000) and included in the list of FEPS currently being developed for Hanford Site assessments (Soler et al. 2001). The current vision for Hanford site-wide cumulative risk assessments as performed using the System Assessment Capability (SAC) is to represent contaminant adsorption using the linear isotherm (empirical distribution coefficient, K d ) sorption model. Integration Project Expert Panel (PEP) comments indicate that work is required to adequately justify the applicability of the linear sorption model, and to identify and defend the range of K d values that are adopted for assessments. The work plans developed for the Science and Technology (S and T) efforts, SAC, and the Core Projects must answer directly the question of ''Is there a scientific basis for the application of the linear sorption isotherm model to the complex wastes of the Hanford Site?'' This paper is intended to address these issues. The reason that well documented justification is required for using the linear sorption (K d ) model is that this approach is strictly empirical and is often

  15. 3D Geospatial Models for Visualization and Analysis of Groundwater Contamination at a Nuclear Materials Processing Facility

    Science.gov (United States)

    Stirewalt, G. L.; Shepherd, J. C.

    2003-12-01

    Analysis of hydrostratigraphy and uranium and nitrate contamination in groundwater at a former nuclear materials processing facility in Oklahoma were undertaken employing 3-dimensional (3D) geospatial modeling software. Models constructed played an important role in the regulatory decision process of the U.S. Nuclear Regulatory Commission (NRC) because they enabled visualization of temporal variations in contaminant concentrations and plume geometry. Three aquifer systems occur at the site, comprised of water-bearing fractured shales separated by indurated sandstone aquitards. The uppermost terrace groundwater system (TGWS) aquifer is composed of terrace and alluvial deposits and a basal shale. The shallow groundwater system (SGWS) aquifer is made up of three shale units and two sandstones. It is separated from the overlying TGWS and underlying deep groundwater system (DGWS) aquifer by sandstone aquitards. Spills of nitric acid solutions containing uranium and radioactive decay products around the main processing building (MPB), leakage from storage ponds west of the MPB, and leaching of radioactive materials from discarded equipment and waste containers contaminated both the TGWS and SGWS aquifers during facility operation between 1970 and 1993. Constructing 3D geospatial property models for analysis of groundwater contamination at the site involved use of EarthVision (EV), a 3D geospatial modeling software developed by Dynamic Graphics, Inc. of Alameda, CA. A viable 3D geohydrologic framework model was initially constructed so property data could be spatially located relative to subsurface geohydrologic units. The framework model contained three hydrostratigraphic zones equivalent to the TGWS, SGWS, and DGWS aquifers in which groundwater samples were collected, separated by two sandstone aquitards. Groundwater data collected in the three aquifer systems since 1991 indicated high concentrations of uranium (>10,000 micrograms/liter) and nitrate (> 500 milligrams

  16. Atmospheric contamination

    International Nuclear Information System (INIS)

    Gruetter, Juerg

    1997-01-01

    It is about the levels of contamination in center America, the population's perception on the problem, effects of the atmospheric contamination, effects in the environment, causes of the atmospheric contamination, possibilities to reduce the atmospheric contamination and list of Roeco Swisscontac in atmospheric contamination

  17. Comparison of Statistically Modeled Contaminated Soil Volume Estimates and Actual Excavation Volumes at the Maywood FUSRAP Site - 13555

    Energy Technology Data Exchange (ETDEWEB)

    Moore, James [U.S. Army Corps of Engineers - New York District 26 Federal Plaza, New York, New York 10278 (United States); Hays, David [U.S. Army Corps of Engineers - Kansas City District 601 E. 12th Street, Kansas City, Missouri 64106 (United States); Quinn, John; Johnson, Robert; Durham, Lisa [Argonne National Laboratory, Environmental Science Division 9700 S. Cass Ave., Argonne, Illinois 60439 (United States)

    2013-07-01

    As part of the ongoing remediation process at the Maywood Formerly Utilized Sites Remedial Action Program (FUSRAP) properties, Argonne National Laboratory (Argonne) assisted the U.S. Army Corps of Engineers (USACE) New York District by providing contaminated soil volume estimates for the main site area, much of which is fully or partially remediated. As part of the volume estimation process, an initial conceptual site model (ICSM) was prepared for the entire site that captured existing information (with the exception of soil sampling results) pertinent to the possible location of surface and subsurface contamination above cleanup requirements. This ICSM was based on historical anecdotal information, aerial photographs, and the logs from several hundred soil cores that identified the depth of fill material and the depth to bedrock under the site. Specialized geostatistical software developed by Argonne was used to update the ICSM with historical sampling results and down-hole gamma survey information for hundreds of soil core locations. The updating process yielded both a best guess estimate of contamination volumes and a conservative upper bound on the volume estimate that reflected the estimate's uncertainty. Comparison of model results to actual removed soil volumes was conducted on a parcel-by-parcel basis. Where sampling data density was adequate, the actual volume matched the model's average or best guess results. Where contamination was un-characterized and unknown to the model, the actual volume exceeded the model's conservative estimate. Factors affecting volume estimation were identified to assist in planning further excavations. (authors)

  18. Gravity models to classify commuting vs. resident workers. An application to the analysis of residential risk in a contaminated area

    Science.gov (United States)

    2011-01-01

    Background The analysis of risk for the population residing and/or working in contaminated areas raises the topic of commuting. In fact, especially in contaminated areas, commuting groups are likely to be subject to lower exposure than residents. Only very recently environmental epidemiology has started considering the role of commuting as a differential source of exposure in contaminated areas. In order to improve the categorization of groups, this paper applies a gravitational model to the analysis of residential risk for workers in the Gela petrochemical complex, which began life in the early 60s in the municipality of Gela (Sicily, Italy) and is the main source of industrial pollution in the local area. Results A logistic regression model is implemented to measure the capacity of Gela "central location" to attract commuting flows from other sites. Drawing from gravity models, the proposed methodology: a) defines the probability of finding commuters from municipalities outside Gela as a function of the origin's "economic mass" and of its distance from each destination; b) establishes "commuting thresholds" relative to the origin's mass. The analysis includes 367 out of the 390 Sicilian municipalities. Results are applied to define "commuters" and "residents" within the cohort of petrochemical workers. The study population is composed of 5,627 workers. Different categories of residence in Gela are compared calculating Mortality Rate Ratios for lung cancer through a Poisson regression model, controlling for age and calendar period. The mobility model correctly classifies almost 90% of observations. Its application to the mortality analysis confirms a major risk for lung cancer associated with residence in Gela. Conclusions Commuting is a critical aspect of the health-environment relationship in contaminated areas. The proposed methodology can be replicated to different contexts when residential information is lacking or unreliable; however, a careful consideration

  19. Gravity models to classify commuting vs. resident workers. An application to the analysis of residential risk in a contaminated area

    Directory of Open Access Journals (Sweden)

    La Rocca Marina

    2011-01-01

    Full Text Available Abstract Background The analysis of risk for the population residing and/or working in contaminated areas raises the topic of commuting. In fact, especially in contaminated areas, commuting groups are likely to be subject to lower exposure than residents. Only very recently environmental epidemiology has started considering the role of commuting as a differential source of exposure in contaminated areas. In order to improve the categorization of groups, this paper applies a gravitational model to the analysis of residential risk for workers in the Gela petrochemical complex, which began life in the early 60s in the municipality of Gela (Sicily, Italy and is the main source of industrial pollution in the local area. Results A logistic regression model is implemented to measure the capacity of Gela "central location" to attract commuting flows from other sites. Drawing from gravity models, the proposed methodology: a defines the probability of finding commuters from municipalities outside Gela as a function of the origin's "economic mass" and of its distance from each destination; b establishes "commuting thresholds" relative to the origin's mass. The analysis includes 367 out of the 390 Sicilian municipalities. Results are applied to define "commuters" and "residents" within the cohort of petrochemical workers. The study population is composed of 5,627 workers. Different categories of residence in Gela are compared calculating Mortality Rate Ratios for lung cancer through a Poisson regression model, controlling for age and calendar period. The mobility model correctly classifies almost 90% of observations. Its application to the mortality analysis confirms a major risk for lung cancer associated with residence in Gela. Conclusions Commuting is a critical aspect of the health-environment relationship in contaminated areas. The proposed methodology can be replicated to different contexts when residential information is lacking or unreliable

  20. Implementation of the NCRP wound model for interpretation of bioassay data for intake of radionuclides through contaminated wounds

    International Nuclear Information System (INIS)

    Ishigure, Nobuhito

    2009-01-01

    Emergency response preparedness for radiological accidents involving wound contamination has become more important, considering the current extending tendency in the nuclear industry related to the nuclear fuel cycle. The US National Council on Radiation Protection and Measurements (NCRP) proposed a biokinetic and dosimetric model for the intake of radionuclides through contaminated wounds in 2007. The present paper describes the implementation of this NCRP wound model for the prediction of systemic behaviour of some important radioactive elements encountered in workplaces related to the nuclear industry. The NCRP wound model was linked to the current ICRP systemic model at each blood compartment and simultaneous differential equations for the content of radioactivity in each compartment and excreta were solved with the Runge-Kutta method. The results of the calculation of wound, whole-body or specific organ retention and daily urinary or faecal excretion rate of some selected elements will be useful for the interpretation of bioassay data and dose assessment for cases of wound contamination. (author)

  1. A model of environmental behaviour of contaminated dust and its application to determining dust fluxes and residence times

    International Nuclear Information System (INIS)

    Allott, R.W.; Kelly, M.; Hewitt, C.N.

    1994-01-01

    A model has been developed to describe the temporal behaviour of the concentrations of a pollutant tracer within the urban environment of Barrow-in-Furness, NW England. The tracer used was 137 Cs derived primarily from wet deposition of the radioactive cloud from the Chernobyl reactor accident. The 137 Cs activity deposited during this primary event was supplemented by a small secondary atmospheric deposition input of resuspended activity. The model was validated against the measured temporal behaviour of 137 Cs in urban dust for two outdoor reservoirs in which the only observed input of dust and activity was by atmospheric deposition. Further modelling studies on other reservoirs (both outdoors and indoors) confirmed the existence of additional input influxes of dust and activity. The model enabled estimates of the magnitudes of these additional fluxes to be made and mean dust mass residence times to be calculated. These residence times correspond to environment half-lives of 170 ± 70 d outdoors and 20 ± 1 d indoors, for reservoirs which only receive a single primary input of a contaminant. Where secondary inputs of pollutants occur, the mean environmental half-lives of the pollutants increase by 50% for outdoor dust reservoirs and over 18-times for indoor reservoirs. This re-contamination of indoor dusts has implications in that attention should be paid to reducing outdoor contamination levels to ensure that attempts to reduce the levels of a pollutant indoors by cleaning are effective. (Author)

  2. Monitoring and modeling of contaminant loads and levels in Norwegian sea 2011

    International Nuclear Information System (INIS)

    Green, Norman W.; Heldal, Hilde Elise; Maage, Amund; Aas, Wenche; Graefert, Torbjoern; Schrum, Corinna; Boitsov, Stepan; Breivik, Knut; Iosjpe, Mikhail; Yakushev, Evgeniy; Skogen, Morten; Hoegaasen, Tore; Eckhardt, Sabine; Christiansen, Anne Bjoerkenes; Daae, Kjersti L.; Durand, Dominique; Ledang, Anna Birgitta; Jaccard, Pierre Francois

    2012-01-01

    This report describes the calculation of the supply of oil, hazardous chemicals and radioactive substances from seven sources of seven regions in the Norwegian part of the Norwegian Sea. The data from the various sources used to calculate the concentrations of pollutants in the water column throughout the defined area of the Norwegian Sea (3 dimensions) and calculate the transport of Hg, PCB153 and BaP in and out of each of the seven regions. This transport flux is huge compared with inputs and will alternately be a net source or net sink of each region. The main feature is that the supply is dominated by the fallout from the atmosphere is balanced by decomposition and sedimentation in the water column plus exports / imports from adjacent waters. It is relatively small supply of hazardous substances. With few exceptions, for the supply of air the biggest contribution of mercury, lead, cadmium, chromium, arsenic, PCBs (PCB-153) and PAH (benzo [a] pyrene) to all regions. Exception contributions of land for chromium in mid-Norway and contributions from seabed for lead and chromium from more central parts of the Norwegian Sea. Ship traffic dominates regard. supply of oil. Supply air from the major contribution of radionuclides plutonium-239 240 and strontium-90 in the eastern part of the Norwegian Sea. Otherwise, Sellafield is the dominant source. Contaminants in sediment and cod were largely of low to moderate concentrations. The concentration of radioactive substances in water, sediment and cod were low and comparable with results from other studies in the Norwegian Sea. There are still large gaps in knowledge and uncertainties in both the data and the estimates of supplies. It is especially important to improved figures for inflows into the oceans via air and enhancement of the marine transport and dispersion models.(eb)

  3. Metagenomic Functional Potential Predicts Degradation Rates of a Model Organophosphorus Xenobiotic in Pesticide Contaminated Soils

    Directory of Open Access Journals (Sweden)

    Thomas C. Jeffries

    2018-02-01

    Full Text Available Chemical contamination of natural and agricultural habitats is an increasing global problem and a major threat to sustainability and human health. Organophosphorus (OP compounds are one major class of contaminant and can undergo microbial degradation, however, no studies have applied system-wide ecogenomic tools to investigate OP degradation or use metagenomics to understand the underlying mechanisms of biodegradation in situ and predict degradation potential. Thus, there is a lack of knowledge regarding the functional genes and genomic potential underpinning degradation and community responses to contamination. Here we address this knowledge gap by performing shotgun sequencing of community DNA from agricultural soils with a history of pesticide usage and profiling shifts in functional genes and microbial taxa abundance. Our results showed two distinct groups of soils defined by differing functional and taxonomic profiles. Degradation assays suggested that these groups corresponded to the organophosphorus degradation potential of soils, with the fastest degrading community being defined by increases in transport and nutrient cycling pathways and enzymes potentially involved in phosphorus metabolism. This was against a backdrop of taxonomic community shifts potentially related to contamination adaptation and reflecting the legacy of exposure. Overall our results highlight the value of using holistic system-wide metagenomic approaches as a tool to predict microbial degradation in the context of the ecology of contaminated habitats.

  4. Self-potential monitoring of a crude oil contaminated site (Trecate, Italy): first results of the modelling.

    Science.gov (United States)

    Giampaolo, V.; Rizzo, E.; Titov, K.; Maineult, A.; Lapenna, V.

    2012-04-01

    , whereas the northern one is characterized by positive values. In contrast, in March, positive SP values generally coincide with the contaminated area. As described by Revil et al. (2010), the capillary fringe of the contaminated portion of the aquifer is potentially the setting of mechanism of electron transfer normal to the water table (due to a higher density of bacteria at the transition zone). This "geo-battery" generates a dipolar self-potential field. In particular, the capillary fringe is higher in October than in March because the rice fields are flooded. Therefore, the water level and the height of the capillary fringe possibly play an important role in the electrochemical mechanism. However, to clearly understand the origin of the measured SP signals, we are building a SP model using vertical dipolar electrical sources, and taking into account the electrical resistivity distribution deduced from ERT an EM measurements. In conclusion, our results confirm that SP can play an important role in the definition of soil hydraulic characteristics and contamination distribution. This work is part of the research project ModelPROBE (Model-Driven soil probing, site assessment and evaluation, Grant No. 213161 in the framework of the EC-FP7 funded).

  5. Analysis of petroleum contaminated soils by spectral modeling and pure response profile recovery of n-hexane

    International Nuclear Information System (INIS)

    Chakraborty, Somsubhra; Weindorf, David C.; Li, Bin; Ali, Md. Nasim; Majumdar, K.; Ray, D.P.

    2014-01-01

    This pilot study compared penalized spline regression (PSR) and random forest (RF) regression using visible and near-infrared diffuse reflectance spectroscopy (VisNIR DRS) derived spectra of 164 petroleum contaminated soils after two different spectral pretreatments [first derivative (FD) and standard normal variate (SNV) followed by detrending] for rapid quantification of soil petroleum contamination. Additionally, a new analytical approach was proposed for the recovery of the pure spectral and concentration profiles of n-hexane present in the unresolved mixture of petroleum contaminated soils using multivariate curve resolution alternating least squares (MCR-ALS). The PSR model using FD spectra (r 2  = 0.87, RMSE = 0.580 log 10  mg kg −1 , and residual prediction deviation = 2.78) outperformed all other models tested. Quantitative results obtained by MCR-ALS for n-hexane in presence of interferences (r 2  = 0.65 and RMSE 0.261 log 10  mg kg −1 ) were comparable to those obtained using FD (PSR) model. Furthermore, MCR ALS was able to recover pure spectra of n-hexane. - Highlights: • We predicted soil petroleum contamination with VisNIR DRS spectra. • We examined 2 spectral pretreatments and 2 multivariate models. • MCR-ALS was used for compositional and spectral resolution of n-hexane. • Penalized spline regression performed best for quantifying soil TPH. • MCR-ALS was promising for resolution of complex soil–petroleum mixture. - Use of VisNIR DRS for rapid quantification of soil TPH and resolution of complex soil petroleum mixtures

  6. GWSCREEN: A semi-analytical model for assessment of the groundwater pathway from surface or buried contamination: Theory and user's manual

    International Nuclear Information System (INIS)

    Rood, A.S.

    1992-03-01

    GWSCREEN was developed for assessment of the groundwater pathway from leaching of radioactive and non radioactive substances from surface or buried sources. The code was designed for implementation in the Track 1 and Track 2 assessment of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites identified as low probability hazard at the Idaho National Engineering Laboratory (DOE, 1991). The code calculates the limiting soil concentration such that regulatory contaminant levels in groundwater are not exceeded. The code uses a mass conservation approach to model three processes: Contaminant release from a source volume, contaminant transport in the unsaturated zone, and contaminant transport in the saturated zone. The source model considers the sorptive properties and solubility of the contaminant. Transport in the unsaturated zone is described by a plug flow model. Transport in the saturated zone is calculated with a semi-analytical solution to the advection dispersion equation for transient mass flux input

  7. GWSCREEN: A semi-analytical model for assessment of the groundwater pathway from surface or buried contamination: Theory and user's manual

    Energy Technology Data Exchange (ETDEWEB)

    Rood, A.S.

    1992-03-01

    GWSCREEN was developed for assessment of the groundwater pathway from leaching of radioactive and non radioactive substances from surface or buried sources. The code was designed for implementation in the Track 1 and Track 2 assessment of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites identified as low probability hazard at the Idaho National Engineering Laboratory (DOE, 1991). The code calculates the limiting soil concentration such that regulatory contaminant levels in groundwater are not exceeded. The code uses a mass conservation approach to model three processes: Contaminant release from a source volume, contaminant transport in the unsaturated zone, and contaminant transport in the saturated zone. The source model considers the sorptive properties and solubility of the contaminant. Transport in the unsaturated zone is described by a plug flow model. Transport in the saturated zone is calculated with a semi-analytical solution to the advection dispersion equation for transient mass flux input.

  8. GWSCREEN: A semi-analytical model for assessment of the groundwater pathway from surface or buried contamination: Theory and user`s manual

    Energy Technology Data Exchange (ETDEWEB)

    Rood, A.S.

    1992-03-01

    GWSCREEN was developed for assessment of the groundwater pathway from leaching of radioactive and non radioactive substances from surface or buried sources. The code was designed for implementation in the Track 1 and Track 2 assessment of Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) sites identified as low probability hazard at the Idaho National Engineering Laboratory (DOE, 1991). The code calculates the limiting soil concentration such that regulatory contaminant levels in groundwater are not exceeded. The code uses a mass conservation approach to model three processes: Contaminant release from a source volume, contaminant transport in the unsaturated zone, and contaminant transport in the saturated zone. The source model considers the sorptive properties and solubility of the contaminant. Transport in the unsaturated zone is described by a plug flow model. Transport in the saturated zone is calculated with a semi-analytical solution to the advection dispersion equation for transient mass flux input.

  9. Hanford Tanks 241-C-203 and 241-C-204: Residual Waste Contaminant Release Model and Supporting Data

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.

    2004-10-28

    This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for the U.S. Department of Energy.

  10. Hanford Tanks 241-C-203 and 241 C 204: Residual Waste Contaminant Release Model and Supporting Data

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.

    2007-05-23

    This report was revised in May 2007 to correct 90Sr values in Chapter 3. The changes were made on page 3.9, paragraph two and Table 3.10; page 3.16, last paragraph on the page; and Tables 3.21 and 3.31. The rest of the text remains unchanged from the original report issued in October 2004. This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for the U.S. Department of Energy.

  11. Hanford Tanks 241-C-203 and 241-C-204: Residual Waste Contaminant Release Model and Supporting Data

    International Nuclear Information System (INIS)

    Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.

    2004-01-01

    This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are (1) future releases from the tanks of the primary contaminants of concern (99Tc and 238U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants; and (2) high percentages of technetium-99 in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to results found in related studies of sludges from Tank AY-102. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for the U.S. Department of Energy

  12. Refinement of a model of repeated cerebrospinal fluid collection in conscious rats.

    Science.gov (United States)

    Amen, Eva Maria; Brecheisen, Muriel; Sach-Peltason, Lisa; Bergadano, Alessandra

    2017-02-01

    The cannulation of the cisterna magna in rats for in vivo sampling of cerebrospinal fluid serves as a valuable model for studying the delivery of new drugs into the central nervous system or disease models. It offers the advantages of repeated sampling without anesthesia-induced bias and using animals as their own controls. An established model was retrospectively reviewed for the outcomes and it was hypothesized that by refining the method, i.e. by (1) implementing pathophysiological-based anesthesia and analgesia, (2) using state-of-the-art peri-operative monitoring and supportive care, (3) increasing stability of the cement-cannula assembly, and (4) selecting a more adaptable animal strain, the outcome in using the model - quantified by peri-operative mortality, survival time and stability of the implant - could be improved and could enhance animal welfare. After refinement of the technique, peri-operative mortality decreased significantly (7 animals out of 73 compared with 4 out of 322; P = 0.001), survival time increased significantly (36 ± 14 days compared with 28 ± 18 days; P concept of Russell and Burch was successfully addressed and animal welfare was improved by (1) the reduction in the total number of animals needed as a result of lower mortality or fewer euthanizations due to technical failure, and frequent use of individual rats over a time frame; and (2) improving the scientific quality of the model.

  13. The Use of Numerical Modeling to Address Surface and Subsurface Water Contamination due to Fracwater Spills in Larry's Creek, Pennsylvania

    Science.gov (United States)

    Simon, C. A.; Arjmand, S.; Abad, J. D.

    2012-12-01

    is to develop a numerical model of the surface and groundwater contaminant transport due to potential spills in the creek. It is important to analyze and understand the migration of pollutants throughout the watershed. In order to do so, the use and development of proper computer models to predict migration of contaminants based on available data is required. Data collected by the Susquehanna River Basin Commission (SRBC) from a station near Saladasburg town will be used to validate and test the accuracy of the model.

  14. Modeling the dark current histogram induced by gold contamination in complementary-metal-oxide-semiconductor image sensors

    Energy Technology Data Exchange (ETDEWEB)

    Domengie, F., E-mail: florian.domengie@st.com; Morin, P. [STMicroelectronics Crolles 2 (SAS), 850 Rue Jean Monnet, 38926 Crolles Cedex (France); Bauza, D. [CNRS, IMEP-LAHC - Grenoble INP, Minatec: 3, rue Parvis Louis Néel, CS 50257, 38016 Grenoble Cedex 1 (France)

    2015-07-14

    We propose a model for dark current induced by metallic contamination in a CMOS image sensor. Based on Shockley-Read-Hall kinetics, the expression of dark current proposed accounts for the electric field enhanced emission factor due to the Poole-Frenkel barrier lowering and phonon-assisted tunneling mechanisms. To that aim, we considered the distribution of the electric field magnitude and metal atoms in the depth of the pixel. Poisson statistics were used to estimate the random distribution of metal atoms in each pixel for a given contamination dose. Then, we performed a Monte-Carlo-based simulation for each pixel to set the number of metal atoms the pixel contained and the enhancement factor each atom underwent, and obtained a histogram of the number of pixels versus dark current for the full sensor. Excellent agreement with the dark current histogram measured on an ion-implanted gold-contaminated imager has been achieved, in particular, for the description of the distribution tails due to the pixel regions in which the contaminant atoms undergo a large electric field. The agreement remains very good when increasing the temperature by 15 °C. We demonstrated that the amplification of the dark current generated for the typical electric fields encountered in the CMOS image sensors, which depends on the nature of the metal contaminant, may become very large at high electric field. The electron and hole emissions and the resulting enhancement factor are described as a function of the trap characteristics, electric field, and temperature.

  15. A chromate-contaminated site in southern Switzerland – Part 2: Reactive transport modeling to optimize remediation options

    International Nuclear Information System (INIS)

    Wanner, Christoph; Eggenberger, Urs; Mäder, Urs

    2012-01-01

    A 2D horizontal reactive transport model of a chromate-contaminated site near Rivera, Switzerland, was developed using the computer code CrunchFlow to evaluate site remediation strategies. Transport processes were defined according to the results of an existing hydrological model, and the definition of geochemical (reactive) processes is based on the results of a detailed mineralogical and geochemical site characterization leading to a comprehensive conceptual site model. Kinetics of naturally occurring Cr(VI) reduction by Fe(II) and natural solid organic matter is quantified by fitting measured Cr isotope ratios to a modeled 1D section along the best constrained flow line. The simulation of Cr isotope fractionation was also incorporated into the 2D model. Simulation of the measured present day Cr(VI) plume and δ 53 Cr value distribution was used for the 2D model calibration and corresponds to a situation where only monitored natural attenuation (MNA) is occurring. Other 2D model runs simulate alternate excavation scenarios. The simulations show that with an excavation of the top 2–4 m the groundwater Cr(VI) plume can be minimized, and that a deeper excavation depth only diminishes the plume if all the contaminants can be removed. A combination of an excavation of the top 2–4 m and monitoring of the ongoing natural Cr(VI) reduction is suggested as the most ecological and economical remediation strategy, even though a remaining time period with ongoing subsoil Cr(VI) contamination in the order of 1 ka is predicted.

  16. Development and validation of a stochastic model for potential growth of Listeria monocytogenes in naturally contaminated lightly preserved seafood.

    Science.gov (United States)

    Mejlholm, Ole; Bøknæs, Niels; Dalgaard, Paw

    2015-02-01

    A new stochastic model for the simultaneous growth of Listeria monocytogenes and lactic acid bacteria (LAB) was developed and validated on data from naturally contaminated samples of cold-smoked Greenland halibut (CSGH) and cold-smoked salmon (CSS). During industrial processing these samples were added acetic and/or lactic acids. The stochastic model was developed from an existing deterministic model including the effect of 12 environmental parameters and microbial interaction (O. Mejlholm and P. Dalgaard, Food Microbiology, submitted for publication). Observed maximum population density (MPD) values of L. monocytogenes in naturally contaminated samples of CSGH and CSS were accurately predicted by the stochastic model based on measured variability in product characteristics and storage conditions. Results comparable to those from the stochastic model were obtained, when product characteristics of the least and most preserved sample of CSGH and CSS were used as input for the existing deterministic model. For both modelling approaches, it was shown that lag time and the effect of microbial interaction needs to be included to accurately predict MPD values of L. monocytogenes. Addition of organic acids to CSGH and CSS was confirmed as a suitable mitigation strategy against the risk of growth by L. monocytogenes as both types of products were in compliance with the EU regulation on ready-to-eat foods. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Equilibrium and kinetic modeling of contaminant immobilization by activated carbon amended to sediments in the field

    NARCIS (Netherlands)

    Rakowska, M.I.; Kupryianchyk, D.; Koelmans, A.A.; Grotenhuis, J.T.C.; Rijnaarts, H.H.M.

    2014-01-01

    Addition of activated carbons (AC) to polluted sediments and soils is an attractive remediation technique aiming at reducing pore water concentrations of hydrophobic organic contaminants (HOCs). In this study, we present (pseudo-)equilibrium as well as kinetic parameters for sorption of a series of

  18. Developing Conceptual Models for Assessing Climate Change Impacts to Contaminant Availability in Terrestrial Ecosystems

    Science.gov (United States)

    2015-03-01

    Greenberg 2005), effects of dredged material (PIANC 2006), and ecosystem restoration (Fischenich 2008) among others. The process of developing a conceptual...Impacts to Contaminant Availability in Terrestrial Ecosystems by Burton C. Suedel, Nathan R. Beane, Eric R. Britzke, Cheryl R. Montgomery, and...are generally project or problem specific. Building a CM includes determining the components of the ecosystem , identifying relationships linking these

  19. Rapid and effective decontamination of chlorophenol-contaminated soil by sorption into commercial polymers: concept demonstration and process modeling.

    Science.gov (United States)

    Tomei, M Concetta; Mosca Angelucci, Domenica; Ademollo, Nicoletta; Daugulis, Andrew J

    2015-03-01

    Solid phase extraction performed with commercial polymer beads to treat soil contaminated by chlorophenols (4-chlorophenol, 2,4-dichlorophenol and pentachlorophenol) as single compounds and in a mixture has been investigated in this study. Soil-water-polymer partition tests were conducted to determine the relative affinities of single compounds in soil-water and polymer-water pairs. Subsequent soil extraction tests were performed with Hytrel 8206, the polymer showing the highest affinity for the tested chlorophenols. Factors that were examined were polymer type, moisture content, and contamination level. Increased moisture content (up to 100%) improved the extraction efficiency for all three compounds. Extraction tests at this upper level of moisture content showed removal efficiencies ≥70% for all the compounds and their ternary mixture, for 24 h of contact time, which is in contrast to the weeks and months, normally required for conventional ex situ remediation processes. A dynamic model characterizing the rate and extent of decontamination was also formulated, calibrated and validated with the experimental data. The proposed model, based on the simplified approach of "lumped parameters" for the mass transfer coefficients, provided very good predictions of the experimental data for the absorptive removal of contaminants from soil at different individual solute levels. Parameters evaluated from calibration by fitting of single compound data, have been successfully applied to predict mixture data, with differences between experimental and predicted data in all cases being ≤3%. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Estimating fate and transport of multiple contaminants in the vadose zone using a multi-layered soil column and three-phase equilibrium partitioning model

    International Nuclear Information System (INIS)

    Rucker, Gregory G.

    2007-01-01

    Soils at waste sites must be evaluated for the potential of residual soil contamination to leach and migrate to the groundwater beneath the disposal area. If migration to the aquifer occurs, contaminants can travel vast distances and pollute drinking water wells, thus exposing human receptors to harmful levels of toxins and carcinogens. To prevent groundwater contamination, a contaminant fate and transport analysis is necessary to assess the migration potential of residual soil contaminants. This type of migration analysis is usually performed using a vadose zone model to account for complex geotechnical and chemical variables including: decay processes, infiltration rate, soil properties, vadose zone thickness, and chemical behavior. The distinct advantage of using a complex model is that less restrictive, but still protective, soil threshold levels may be determined avoiding the unnecessary and costly remediation of marginally contaminated soils. However, the disadvantage of such modeling is the additional cost for data collection and labor required to apply these models. In order to allay these higher costs and to achieve a less restrictive but still protective clean-up level, a multiple contaminant and multi layered soil column equilibrium partitioning model was developed which is faster, simpler and less expensive to use. (authors)

  1. Quantitative model of the effects of contamination and space environment on in-flight aging of thermal coatings

    Science.gov (United States)

    Vanhove, Emilie; Roussel, Jean-François; Remaury, Stéphanie; Faye, Delphine; Guigue, Pascale

    2014-09-01

    The in-orbit aging of thermo-optical properties of thermal coatings critically impacts both spacecraft thermal balance and heating power consumption. Nevertheless, in-flight thermal coating aging is generally larger than the one measured on ground and the current knowledge does not allow making reliable predictions1. As a result, a large oversizing of thermal control systems is required. To address this issue, the Centre National d'Etudes Spatiales has developed a low-cost experiment, called THERME, which enables to monitor the in-flight time-evolution of the solar absorptivity of a large variety of coatings, including commonly used coatings and new materials by measuring their temperature. This experiment has been carried out on sunsynchronous spacecrafts for more than 27 years, allowing thus the generation of a very large set of telemetry measurements. The aim of this work was to develop a model able to semi-quantitatively reproduce these data with a restraint number of parameters. The underlying objectives were to better understand the contribution of the different involved phenomena and, later on, to predict the thermal coating aging at end of life. The physical processes modeled include contamination deposition, UV aging of both contamination layers and intrinsic material and atomic oxygen erosion. Efforts were particularly focused on the satellite leading wall as this face is exposed to the highest variations in environmental conditions during the solar cycle. The non-monotonous time-evolution of the solar absorptivity of thermal coatings is shown to be due to a succession of contamination and contaminant erosion by atomic oxygen phased with the solar cycle.

  2. Environmental Contamination as an Important Route for the Transmission of the Hospital Pathogen VRE: Modeling and Prediction of Classical Interventions

    Directory of Open Access Journals (Sweden)

    M Wolkewitz

    2008-01-01

    Full Text Available Background In addition to the close contact between patients and medical staff, the contamination of surfaces plays an important role in the transmission of pathogens such as vancomycin-resistant enterococci (VRE. Mathematical modeling is a very convenient tool for hospital infection control as it allows the quantitative prediction of the effects of special hygiene and control interventions. Methods We present a compartmental model which describes the dynamics of transmission from patient to patient, also taking into account the interaction with medical staff and environmental contamination. Empirical data from a VRE outbreak in the onco-haematological unit at the University Medical Center Freiburg (Germany were collected with 100 consecutive admissions being followed up for 90 days. Stochastical simulations were used to predict the prevalence of patients colonised with VRE at the time when at least one of the following interventions were introduced: hand hygiene, disinfection of surfaces, cohorting, screening and antibiotic reduction. Results Graphical figures show the temporal dynamics of several simulation scenarios. If no prevention or intervention is present, simulations based on transmission models predict an expected endemic prevalence per ward of 0.83 (95% CI:0.66, 1.00 after the first infected person enters the unit. Interventions may reduce this prevalence, but only the combination of several interventions can control a VRE outbreak. Conclusions The model predicts that only the combination of several interventions can control an VRE outbreak in this setting. The inclusion of environmental contamination improves the compartmental model and allows a prediction of the efficacy of the disinfection of surfaces. These results can be applied to other settings and will therefore help to understand and control the spread of nosocomial pathogens.

  3. A dynamic contaminant fate model of organic compound: a case study of Nitrobenzene pollution in Songhua River, China.

    Science.gov (United States)

    Wang, Ce; Feng, Yujie; Zhao, Shanshan; Li, Bai-Lian

    2012-06-01

    A one-dimensional dynamic contaminant fate model, coupling kinematic wave flow option with advection-dispersion-reaction equation, has been applied to predict Nitrobenzene pollution emergency in Songhua River, China that occurred on November 13, 2005. The model includes kinetic processes including volatilization, photolysis and biodegradation, and diffusive mass exchange between water column and sediment layer as a function of particles settling and resuspension. Four kinds of quantitative statistical tests, namely Nash-Sutcliffe efficiency, percent bias, ratio of root-mean-square to the standard deviation of monitoring data and Theil's inequality coefficient, are adopted to evaluate model performance. The results generally show that the modeled and detected concentrations exhibit good consistency. Flow velocity in the river is most sensitive parameter to Nitrobenzene concentration in water column based on sensitivity analysis of input parameters. It indicates flow velocity has important impact on both distribution and variance of contaminant concentration. The model performs satisfactory for prediction of organic pollutant fate in Songhua River, with the ability to supply necessary information for pollution event control and early warning, which could be applied to similar long natural rivers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Evaluation and determination of soil remediation schemes using a modified AHP model and its application in a contaminated coking plant.

    Science.gov (United States)

    Li, Xingang; Li, Jia; Sui, Hong; He, Lin; Cao, Xingtao; Li, Yonghong

    2018-07-05

    Soil remediation has been considered as one of the most difficult pollution treatment tasks due to its high complexity in contaminants, geological conditions, usage, urgency, etc. The diversity in remediation technologies further makes quick selection of suitable remediation schemes much tougher even the site investigation has been done. Herein, a sustainable decision support hierarchical model has been developed to select, evaluate and determine preferred soil remediation schemes comprehensively based on modified analytic hierarchy process (MAHP). This MAHP method combines competence model and the Grubbs criteria with the conventional AHP. It not only considers the competence differences among experts in group decision, but also adjusts the big deviation caused by different experts' preference through sample analysis. This conversion allows the final remediation decision more reasonable. In this model, different evaluation criteria, including economic effect, environmental effect and technological effect, are employed to evaluate the integrated performance of remediation schemes followed by a strict computation using above MAHP. To confirm the feasibility of this developed model, it has been tested by a benzene workshop contaminated site in Beijing coking plant. Beyond soil remediation, this MAHP model would also be applied in other fields referring to multi-criteria group decision making. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Contamination Analyzer

    Science.gov (United States)

    1994-01-01

    Measurement of the total organic carbon content in water is important in assessing contamination levels in high purity water for power generation, pharmaceutical production and electronics manufacture. Even trace levels of organic compounds can cause defects in manufactured products. The Sievers Model 800 Total Organic Carbon (TOC) Analyzer, based on technology developed for the Space Station, uses a strong chemical oxidizing agent and ultraviolet light to convert organic compounds in water to carbon dioxide. After ionizing the carbon dioxide, the amount of ions is determined by measuring the conductivity of the deionized water. The new technique is highly sensitive, does not require compressed gas, and maintenance is minimal.

  6. Modeling interactions of agriculture and groundwater nitrate contaminants: application of The STICS-Eau-Dyssée coupled models over the Seine River Basin

    Science.gov (United States)

    Tavakoly, A. A.; Habets, F.; Saleh, F.; Yang, Z. L.

    2017-12-01

    Human activities such as the cultivation of N-fixing crops, burning of fossil fuels, discharging of industrial and domestic effluents, and extensive usage of fertilizers have recently accelerated the nitrogen loading to watersheds worldwide. Increasing nitrate concentration in surface water and groundwater is a major concern in watersheds with extensive agricultural activities. Nutrient enrichment is one of the major environmental problems in the French coastal zone. To understand and predict interactions between agriculture, surface water and groundwater nitrate contaminants, this study presents a modeling framework that couples the agronomic STICS model with Eau-Dyssée, a distributed hydrologic modeling system to simulate groundwater-surface water interaction. The coupled system is implemented on the Seine River Basin with an area of 88,000 km2 to compute daily nitrate contaminants. Representing a sophisticated hydrosystem with several aquifers and including the megalopolis of Paris, the Seine River Basin is well-known as one of the most productive agricultural areas in France. The STICS-EauDyssée framework is evaluated for a long-term simulation covering 39 years (1971-2010). Model results show that the simulated nitrate highly depends on the inflow produced by surface and subsurface waters. Daily simulation shows that the model captures the seasonal variation of observations and that the overall long-term simulation of nitrate contaminant is satisfactory at the regional scale.

  7. Physical model of the dispersion of a radioactive contaminant in the atmosphere above a heat island

    International Nuclear Information System (INIS)

    Toly, J.A.; Tenchine, D.

    1984-01-01

    The project deals with the impact of surface heating in urban areas on the dispersion of contaminants in the atmosphere. - The atmospheric boundary layer is simulated in a water flume. Ground heating is applied locally reproducing the heat flux of an urban region. Fission products for which internal heat source is neglected are simulated by horizontal plumes at pHs different from the original pH of the flume. - The main results of the study concern: the characterization of the internal boundary layer downstream of the leading edge of the heated ground; the comparison of the concentration distributions of pollutants with and without surface heating. - A transposition of the results, expressed in terms of global parameters, enables information on the heat island effect due to urban regions on the dispersion of contaminants in the atmosphere to be obtained

  8. Plasma-based water treatment: development of a general mechanistic model to estimate the treatability of different types of contaminants

    International Nuclear Information System (INIS)

    Mededovic Thagard, Selma; Stratton, Gunnar R; Paek, Eunsu; Dai, Fei; Holsen, Thomas M; Bellona, Christopher L; Bohl, Douglas G; Dickenson, Eric R V

    2017-01-01

    To determine the types of applications for which plasma-based water treatment (PWT) is best suited, the treatability of 23 environmental contaminants was assessed through treatment in a gas discharge reactor with argon bubbling, termed the enhanced-contact reactor. The contaminants were treated in a mixture to normalize reaction conditions and convective transport limitations. Treatability was compared in terms of the observed removal rate constant ( k obs ). To characterize the influence of interfacial processes on k obs , a model was developed that accurately predicts k obs for each compound, as well as the contributions to k obs from each of the three general degradation mechanisms thought to occur at or near the gas–liquid interface: ‘sub-surface’, ‘surface’ and ‘above-surface’. Sub-surface reactions occur just underneath the gas–liquid interface between the contaminants and dissolved plasma-generated radicals, contributing significantly to the removal of compounds that lack surfactant-like properties and so are not highly concentrated at the interface. Surface reactions occur at the interface between the contaminants and dissolved radicals, contributing significantly to the removal of surfactant-like compounds that have high interfacial concentrations. The contaminants’ interfacial concentrations were calculated using surface-activity parameters determined through surface tension measurements. Above-surface reactions are proposed to take place in the plasma interior between highly energetic plasma species and exposed portions of compounds that extend out of the interface. This mechanism largely accounts for the degradation of surfactant-like contaminants that contain highly hydrophobic perfluorocarbon groups, which are most likely to protrude from the interface. For a few compounds, the degree of exposure to the plasma interior was supported by new and previously reported molecular dynamics simulations results. By reviewing the predicted

  9. Plasma-based water treatment: development of a general mechanistic model to estimate the treatability of different types of contaminants

    Science.gov (United States)

    Mededovic Thagard, Selma; Stratton, Gunnar R.; Dai, Fei; Bellona, Christopher L.; Holsen, Thomas M.; Bohl, Douglas G.; Paek, Eunsu; Dickenson, Eric R. V.

    2017-01-01

    To determine the types of applications for which plasma-based water treatment (PWT) is best suited, the treatability of 23 environmental contaminants was assessed through treatment in a gas discharge reactor with argon bubbling, termed the enhanced-contact reactor. The contaminants were treated in a mixture to normalize reaction conditions and convective transport limitations. Treatability was compared in terms of the observed removal rate constant (k obs). To characterize the influence of interfacial processes on k obs, a model was developed that accurately predicts k obs for each compound, as well as the contributions to k obs from each of the three general degradation mechanisms thought to occur at or near the gas-liquid interface: ‘sub-surface’, ‘surface’ and ‘above-surface’. Sub-surface reactions occur just underneath the gas-liquid interface between the contaminants and dissolved plasma-generated radicals, contributing significantly to the removal of compounds that lack surfactant-like properties and so are not highly concentrated at the interface. Surface reactions occur at the interface between the contaminants and dissolved radicals, contributing significantly to the removal of surfactant-like compounds that have high interfacial concentrations. The contaminants’ interfacial concentrations were calculated using surface-activity parameters determined through surface tension measurements. Above-surface reactions are proposed to take place in the plasma interior between highly energetic plasma species and exposed portions of compounds that extend out of the interface. This mechanism largely accounts for the degradation of surfactant-like contaminants that contain highly hydrophobic perfluorocarbon groups, which are most likely to protrude from the interface. For a few compounds, the degree of exposure to the plasma interior was supported by new and previously reported molecular dynamics simulations results. By reviewing the predicted

  10. Modeling technique for optimal recovery of immiscible light hydrocarbons as free product from contaminated aquifer

    OpenAIRE

    Cooper, Grant S., Jr.; Peralta, R. C.; Kaluarachchi, J. J.

    1993-01-01

    Contamination sites associated with light non-aqueous phase liquids {LNAPL) are numerous and represent difficult cleanup problems. Remediation methods for cleanup of LNAPL fluids in subsurface systems are continuously evolving with the development of various technologies for pump.-and~treat, soil venting, and in-situ bioremediation. Evaluating the effectiveness of remediation techniques as well as attempting to improve their efficiency has been a focus of many researchers, These efforts have ...

  11. Modelling of contaminant migration in acidic groundwater plumes at uranium tailings impoundments: ADNEUT3

    International Nuclear Information System (INIS)

    Cherry, J.A.; Morin, K.A.; Dubrovsky, N.M.

    1984-06-01

    This report describes the creation and application of ADNEUT3, the latest addition to the ADNEUT (Acid-Drainage NEUTralization) family of computer programs for simulating acid-drainage transport and neutralization. The creation of ADNEUT3 involved the expansion of ADNEUT1 to allow variable input conditions such as changing input solution with time, variable initial amounts of minerals through the simulated streamtube, variable velocities through the streamtube, and variable solubilities for relevant minerals dependent on aqueous chemical composition. Concepts for simulating acid-drainage neutralization are reviewed and ADNEUT3 is then applied to a field-study site of acidic contaminant migration from the Nordic Main uranium-tailings impoundment near Elliot Lake, Ontario. A sensitivity study is first implemented to calibrate ADNEUT3 to the results of the 1979 to 1983 field studies. Then ADNEUT3 is used to define probable past conditions at the site which are not reliably known. In particular, ADNEUT3 is used to help identify: 1) the approximate year when acidic seepage began leaving the tailings impoundment (1966-1967), 2) the past chemical composition of the seepage (somewhat more acidic for a short period of time), and 3) the location of the source area within the tailings for the acidic seepage (near the impoundment dam, close to the field site). Finally, ADNEUT3 is used to predict future contaminant migration. Results indicate that hundreds of years are required under present conditions for the most acidic water with associated high levels of contaminants to migrate about 100 m from the tailings impoundment. The cause of this slow movement is the significant neutralization capacity of the aquifer. If acid production within the tailings decreases in the future, migration rates of contaminants will also decrease

  12. Long term contaminant migration and impacts from uranium mill tailings. Comparison of computer models using a hypothetical dataset

    International Nuclear Information System (INIS)

    Camus, H.

    1995-11-01

    The Uranium Mill Tailings Working Group of BIOMOVS II was initiated in Vienna in 1991 with the primary objective of comparing models which can be used to assess the long term impact of radioactive releases from uranium mill tailings, involving multiple pathways, multiple contaminants and multiple environmental receptors. A secondary objective was to examine how these models can be used to assess the fate of stable toxic elements. This is an interim report of the Working Group describing: development of a basic scenario describing a tailings system; application of models in deterministic calculations of contaminant concentrations in biosphere media, and related radiation doses, contaminant intakes and health risks; comparison of model results and review of the modelling. A hypothetical scenario has been developed for contaminant releases from a uranium mill tailings facility. The assumptions for the tailings facility and its environs have been chosen to facilitate the evaluation of potentially important processes incorporated into models. The site description is therefore idealised and does not represent any particular facility or type of facility. Atmospheric and groundwater release source terms have been chosen to facilitate comparison of models and should not be considered realistic. The time and effort taken over derivation of the scenario description and the associated preliminary modelling has been an important and valuable learning exercise. It also reflects the importance of gaining a clear picture of what is being modelled so that comparisons of model results are meaningful. Work within the exercise has contributed to new model development and to improvements and extensions to existing models. The scenario is a simplified description of a real facility and the releases which might occur. No allowance has been made for engineered features on the tailings disposal system which might reduce releases. The source terms have been chosen so as to test the models

  13. Long term contaminant migration and impacts from uranium mill tailings. Comparison of computer models using a hypothetical dataset

    Energy Technology Data Exchange (ETDEWEB)

    Camus, H [CEA Centre d' Etudes Nucleaires de Fontenay-aux-Roses (France). Inst. de Protection et de Surete Nucleaire; and others

    1995-11-01

    The Uranium Mill Tailings Working Group of BIOMOVS II was initiated in Vienna in 1991 with the primary objective of comparing models which can be used to assess the long term impact of radioactive releases from uranium mill tailings, involving multiple pathways, multiple contaminants and multiple environmental receptors. A secondary objective was to examine how these models can be used to assess the fate of stable toxic elements. This is an interim report of the Working Group describing: development of a basic scenario describing a tailings system; application of models in deterministic calculations of contaminant concentrations in biosphere media, and related radiation doses, contaminant intakes and health risks; comparison of model results and review of the modelling. A hypothetical scenario has been developed for contaminant releases from a uranium mill tailings facility. The assumptions for the tailings facility and its environs have been chosen to facilitate the evaluation of potentially important processes incorporated into models. The site description is therefore idealised and does not represent any particular facility or type of facility. Atmospheric and groundwater release source terms have been chosen to facilitate comparison of models and should not be considered realistic. The time and effort taken over derivation of the scenario description and the associated preliminary modelling has been an important and valuable learning exercise. It also reflects the importance of gaining a clear picture of what is being modelled so that comparisons of model results are meaningful. Work within the exercise has contributed to new model development and to improvements and extensions to existing models. The scenario is a simplified description of a real facility and the releases which might occur. No allowance has been made for engineered features on the tailings disposal system which might reduce releases. The source terms have been chosen so as to test the models

  14. Designing the ideal model for assessment of wound contamination after gunshot injuries: a comparative experimental study

    Directory of Open Access Journals (Sweden)

    von See Constantin

    2012-04-01

    Full Text Available Abstract Background Modern high-velocity projectiles produce temporary cavities and can thus cause extensive tissue destruction along the bullet path. It is still unclear whether gelatin blocks, which are used as a well-accepted tissue simulant, allow the effects of projectiles to be adequately investigated and how these effects are influenced by caliber size. Method Barium titanate particles were distributed throughout a test chamber for an assessment of wound contamination. We fired .22-caliber Magnum bullets first into gelatin blocks and then into porcine hind limbs placed behind the chamber. Two other types of bullets (.222-caliber bullets and 6.5 × 57 mm cartridges were then shot into porcine hind limbs. Permanent and temporary wound cavities as well as the spatial distribution of barium titanate particles in relation to the bullet path were evaluated radiologically. Results A comparison of the gelatin blocks and hind limbs showed significant differences (p Conclusion Gelatin is only of limited value for evaluating the path of high-velocity projectiles and the contamination of wounds by exogenous particles. There is a direct relationship between the presence of gas cavities in the tissue along the bullet path and caliber size. These cavities, however, are only mildly contaminated by exogenous particles.

  15. Application of an in vivo swine model for the determination of arsenic bioavailability in contaminated vegetables.

    Science.gov (United States)

    Juhasz, Albert L; Smith, Euan; Weber, John; Rees, Matthew; Rofe, Allan; Kuchel, Tim; Sansom, Lloyd; Naidu, Ravi

    2008-05-01

    Considerable information is available in the literature regarding the uptake of arsenic (As) from contaminated soil and irrigation water by vegetables. However, few studies have investigated As speciation in these crops while a dearth of information is available on As bioavailability following their consumption. In this study, the concentration and speciation of As in chard, radish, lettuce and mung beans was determined following hydroponic growth of the vegetables using As-contaminated water. In addition, As bioavailability was assessed using an in vivo swine feeding assay. While As concentrations ranged from 3.0 to 84.2mg As kg(-1) (dry weight), only inorganic As (arsenite and arsenate) was detected in the edible portions of the vegetables. When As bioavailability was assessed through monitoring blood plasma As concentrations following swine consumption of As-contaminated vegetables, between 50% and 100% of the administered As dose was absorbed and entered systemic circulation. Arsenic bioavailability decreased in the order mung beans>radish>lettuce=chard.

  16. Revitalization model of tapioca industry through environmental awareness reinforcement for minimizing water body contamination

    Science.gov (United States)

    Banowati, E.; Indriyanti, D. R.; Juhadi

    2018-03-01

    Tapioca industry in Margoyoso District is a household industry which positively contributes to the growth of the region's economy as it is able to absorb 6,61% of productive age populationor absorb 3,300 workers.On the other hand, the industry impacts contamination of river water in the form of pollutants dissolved materials and particulates into water bodies so that the quality of water decreases even does not work anymore in accordance with the allocation for irrigation or run off of agriculture. The purpose of this research is to: strengthen environmental awareness; calculate the success of the reinforcement action and minimize water body contamination. The research was conducted in two villages of tapioca industry center in Margoyoso district - Pati Regency Administration Area. The determination coefficient of R Square is 0.802 which indicates a successful effort of 80.2%. Regression equation Y = 34.097 + 0.608 X. Industrial entrepreneur's concern increased on 8.45 from total indicator or position to 70.72 so that the gradual effort showed success to minimize water contamination of Suwatu River. The business community of tapioca should build installation of wastewater treatment.

  17. Long term contaminant migration and impacts from uranium mill tailings. Comparison of computer models using a realistic dataset

    Energy Technology Data Exchange (ETDEWEB)

    Camus, H. [CEA Centre d' Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire] [and others

    1996-08-01

    This is the final report of the Working Group describing: the enhancement of the previously devised V1 scenario to produce a V2 scenario which includes more detailed source term and other site specific data; the application of models in deterministic and probabilistic mode to calculate contaminant concentrations in biosphere media, and related radiation doses, contaminant intakes and health risks, including estimates of uncertainties; the comparison and analysis of the resulting calculations. A series of scenarios was developed based on data provided by Working Group members from a range of actual tailings disposal sites, culminating in the V2.2 and V2.3 scenarios. The V2.2 and V2.3 scenarios are identical in all respects, except that the V2.2 considers radioactive (U-238 chain) contaminants, whilst the V2.3 considers stable elements (As, Ni, Pb). Since the scenarios are based on data obtained from a range of actual sites, they should be considered to be generically realistic rather than representative of a particular single site. In both scenarios, the contaminants of interest are assumed to be released in leachate from a tailings pile into an underlying aquifer. They are transported in groundwater through the aquifer to a well. Water is abstracted from the well and used for: watering beef cattle; human consumption; and irrigating leafy vegetables. The beef and leafy vegetables are consumed by humans living in the area. The same contaminants are also released into the atmosphere due to the wind erosion of the pile and then deposited upon the soil, pasture and leafy vegetables. In addition, for the V2.2 scenario, Rn-222 is assumed to be released to atmosphere from the pile. Unlike the V1 scenario, no consideration is given to surface water exposure pathways. Results show that there is exceedingly good agreement between participants' deterministic and probabilistic estimates of total dose or intake. They agree within a factor of two to three for both scenarios

  18. Long term contaminant migration and impacts from uranium mill tailings. Comparison of computer models using a realistic dataset

    International Nuclear Information System (INIS)

    Camus, H.

    1996-08-01

    This is the final report of the Working Group describing: the enhancement of the previously devised V1 scenario to produce a V2 scenario which includes more detailed source term and other site specific data; the application of models in deterministic and probabilistic mode to calculate contaminant concentrations in biosphere media, and related radiation doses, contaminant intakes and health risks, including estimates of uncertainties; the comparison and analysis of the resulting calculations. A series of scenarios was developed based on data provided by Working Group members from a range of actual tailings disposal sites, culminating in the V2.2 and V2.3 scenarios. The V2.2 and V2.3 scenarios are identical in all respects, except that the V2.2 considers radioactive (U-238 chain) contaminants, whilst the V2.3 considers stable elements (As, Ni, Pb). Since the scenarios are based on data obtained from a range of actual sites, they should be considered to be generically realistic rather than representative of a particular single site. In both scenarios, the contaminants of interest are assumed to be released in leachate from a tailings pile into an underlying aquifer. They are transported in groundwater through the aquifer to a well. Water is abstracted from the well and used for: watering beef cattle; human consumption; and irrigating leafy vegetables. The beef and leafy vegetables are consumed by humans living in the area. The same contaminants are also released into the atmosphere due to the wind erosion of the pile and then deposited upon the soil, pasture and leafy vegetables. In addition, for the V2.2 scenario, Rn-222 is assumed to be released to atmosphere from the pile. Unlike the V1 scenario, no consideration is given to surface water exposure pathways. Results show that there is exceedingly good agreement between participants' deterministic and probabilistic estimates of total dose or intake. They agree within a factor of two to three for both scenarios. Even

  19. An integrated model for assessing the risk of TCE groundwater contamination to human receptors and surface water ecosystems

    DEFF Research Database (Denmark)

    McKnight, Ursula S.; Funder, S.G.; Rasmussen, J.J.

    2010-01-01

    The practical implementation of the European Water Framework Directive has resulted in an increased focus on the hyporheic zone. In this paper, an integrated model was developed for evaluating the impact of point sources in groundwater on human health and surface water ecosystems....... This was accomplished by coupling the system dynamics-based decision support system CARO-PLUS to the aquatic ecosystem model AQUATOX using an analytical volatilization model for the stream. The model was applied to a case study where a TCE contaminated groundwater plume is discharging to a stream. The TCE source...... will not be depleted for many decades, however measured and predicted TCE concentrations in surface water were found to be below human health risk management targets. Volatilization rapidly attenuates TCE concentrations in surface water. Thus, only a 300 m stream reach fails to meet surface water quality criteria...

  20. Human radiation dose resulting from forests contaminated by radionuclides: generic model and applications to the Chernobyl ecosystems

    International Nuclear Information System (INIS)

    Linkov, I.; Harvard Univ., Cambridge, MA; Schell, W.R.

    1996-01-01

    Forest ecosystems have been found to contribute significantly to the human radiation dose in the intermediate and long teens following radionuclide releases. Evaluation of the internal and external radiation dose for these critical population groups requires knowledge of radionuclide transport processes in forest ecosystems, as well as the extent of forest utilization by these populations. The high complexity of the problem requires the use of models to define and analyze the properties of the forest as well as to evaluate the ecosystem response to possible human intervention. A generic FORESTPATH model is used to calculate the internal and external radiation doses for different critical groups of consumers at different times following radionuclide release. The model is tested using the information available for contaminated forests in Belarus. Uncertainty of the model predictions are estimated by means of Monte-Carlo simulations. (author)

  1. Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

    International Nuclear Information System (INIS)

    Voglar, Grega E.; Lestan, Domen

    2011-01-01

    Highlights: → We assess the feasibility of using soil S/S for industrial land reclamation. → Retarders, accelerators, plasticizers were used in S/S cementitious formulation. → We proposed novel S/S efficiency model for multi-metal contaminated soils. - Abstract: In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085 mg kg -1 of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12 N mm -2 achieved after S/S with CAC + PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC + Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively.

  2. Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

    Energy Technology Data Exchange (ETDEWEB)

    Voglar, Grega E. [RDA - Regional Development Agency Celje, Kidriceva ulica 25, 3000 Celje (Slovenia); Lestan, Domen, E-mail: domen.lestan@bf.uni-lj.si [Agronomy Department, Centre for Soil and Environmental Science, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana (Slovenia)

    2011-08-30

    Highlights: {yields} We assess the feasibility of using soil S/S for industrial land reclamation. {yields} Retarders, accelerators, plasticizers were used in S/S cementitious formulation. {yields} We proposed novel S/S efficiency model for multi-metal contaminated soils. - Abstract: In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085 mg kg{sup -1} of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12 N mm{sup -2} achieved after S/S with CAC + PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC + Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively.

  3. An outline of a model-based expert system to identify optimal remedial strategies for restoring contaminated aquatic ecosystems: the project MOIRA

    International Nuclear Information System (INIS)

    Appelgren, A.; Bergstrom, U.; Brittain, J.; Monte, L.

    1996-10-01

    The present report describes the fundamental principles of the research programme MOIRA (a model based computerized system for management support to Identify optimal remedial strategies for Restoring radionuclide contaminated Aquatic ecosystems and drainage areas) financed by the EC (European Community) (Contract N F14P-CT96-0036). The interventions to restore radionuclides contaminated aquatic systems may result in detrimental ecological, social and economical effects. Decision makers must carefully evaluate these impacts. The main aim of the MOIRA project is the development of an expert system based on validated models predicting the evolution of the radioactive contamination of fresh water systems following countermeasure applications and their relevant ecological, social and economical impacts. The expert system will help decision makers, that are not necessarily gifted with experience in environmental modeling, to identify optimal remedial strategies for restoring contaminated fresh water systems

  4. An outline of a model-based expert system to identify optimal remedial strategies for restoring contaminated acquatic ecosystems: The project ``moira``

    Energy Technology Data Exchange (ETDEWEB)

    Appelgren, A.; Bergstrom, U. [Studsvik Eco and AB, Nykoping (Sweden); Brittain, J. [Oslo Univ. (Norway). LFI Zoological Museum; Gallego Diaz, E. [Madrid Universidad Politecnica (Spain). Dept. de Ingenieria Nuclear; Hakanson, L. [KEMA Nuclear, Arnhem (Niger); Monte, L. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dip. Ambiente

    1996-10-01

    The present report describes the fundamental principles of the research programme MOIRA (a model based computerized system for management support to Identify optimal remedial strategies for Restoring radionuclide contaminated Aquatic ecosystems and drainage areas) financed by the EC (European Community) (Contract N F14P-CT96-0036). The interventions to restore radionuclides contaminated aquatic systems may result in detrimental ecological, social and economical effects. Decision makers must carefully evaluate these impacts. The main aim of the MOIRA project is the development of an expert system based on validated models predicting the evolution of the radioactive contamination of fresh water systems following countermeasure applications and their relevant ecological, social and economical impacts. The expert system will help decision makers, that are not necessarily gifted with experience in environmental modeling, to identify optimal remedial strategies for restoring contaminated fresh water systems.

  5. Experimental models in the rat for the assessment of local and systemic behaviour and decorporation of MOX after contamination by wounding

    International Nuclear Information System (INIS)

    Griffiths, N.M.; Van der Meeren, A.; Abram, M.C.; Chau, Q.; Coudert, S.; Renault, D.; Wilk, J.C.; Guichet, C.; Helfer, N.; Angulo-Mora, J.

    2013-11-01

    Accidental contamination of nuclear industry workers by alpha particle-emitting actinides (plutonium; Pu, americium; Am) can occur after wounding. Transfer from the wound depends on contaminant physicochemical properties, wound type and anatomical location. These factors and wound activity levels direct the ensuing medical approaches. The principal objective of this research program, carried out in the Laboratoire de Radio-Toxicologie (CEA/DSV) in collaboration with AREVA NC, was to establish models of actinide-contaminated wounds in the rat using multidisciplinary approaches. Rats were contaminated by MOX (7.1% Pu by mass) or Pu nitrate or Am nitrate, either by subcutaneous implantation of an agarose gel containing the radioelement or following incision of the hind limb muscles. Actinide urinary excretion, wound, tissue levels and effects of decorporant regimens including wound excision were evaluated. In both experimental models following MOX contamination, urinary Am excretion was greater than Pu, and bone Pu and Am retention increased significantly with time. Moreover after Pu or Am nitrate contamination, Am excretion and tissue retention was greater than Pu again reflecting the higher solubility of Am. Coherent with the insoluble nature of oxide forms, tissue Am or Pu levels were much lower after MOX compared to those seen after nitrates. Wound site actinide retention was also much higher after MOX contamination. Repeated systemic DTPA increased actinide urinary excretion and decreased tissue retention, as did single or repeated local DTPA. Pu urinary excretion was transiently increased after wound excision but no further Pu organ retention was observed. In conclusion, several different experimental models have been developed in the rat to simulate actinide wound contamination. Information obtained on Pu and Am behavior either at the wound site or at distant organs allowed the discrimination between different physicochemical actinide forms and evaluation of

  6. STakeholder-Objective Risk Model (STORM): Determiningthe aggregated risk of multiple contaminant hazards in groundwater well catchments

    DEFF Research Database (Denmark)

    Enzenhoefer, R.; Binning, Philip John; Nowak, W.

    2015-01-01

    Risk is often defined as the product of probability, vulnerability and value. Drinking water supply from groundwater abstraction is often at risk due to multiple hazardous land use activities in the well catchment. Each hazard might or might not introduce contaminants into the subsurface at any......-pathway-receptor concept, mass-discharge-based aggregation of stochastically occuring spill events, accounts for uncertainties in the involved flow and transport models through Monte Carlo simulation, and can address different stakeholder objectives. We illustrate the application of STORM in a numerical test case inspired...

  7. Evaluation of a cross contamination model describing transfer of salmonella spp. and listeria monocytogenes during grinding of pork and beef

    DEFF Research Database (Denmark)

    Møller, Cleide Oliveira de Almeida; Hansen, Tina Beck; Aabo, Søren

    2015-01-01

    Introduction: The cross contamination model (Møller et al. 2012) was evaluated to investigate its capability of describing transfer of Salmonella spp. and Listeria monocytogenes during grinding of pork and beef of varying sizes (50 – 324 g) and numbers of pieces to be ground (10 – 100), in two...... processing. QMRA risk estimates and TTP both revealed that risk attribution from grinding was mainly influenced by sharpness of grinder knife > specific grinder > grinding temperature whereas the specific pathogen was of minor importance....

  8. Consumer contribution to food contamination in Brazil: modelling the food safety risk in the home

    Directory of Open Access Journals (Sweden)

    Sergio Paulo Olinto da Motta

    2014-06-01

    Full Text Available Foodborne diseases are among the most widespread public health issues, killing about 2.2 million people annually, and costing hundreds of billions of US dollars for governments, companies, families and consumers (WHO, 2007. In Brazil, foodborne diseases acquired in the home account for 55% of notified outbreaks (BRASIL, 2012. Several studies have investigated aspects of consumer behaviour concerning food poisoning, mapping practices in the home, but it remains a challenge to obtain a full picture of the consumer contribution to food contamination (REDMOND and GRIFFITH, 2003. This study aimed to assess the risks of food contamination in the home. A questionnaire containing 140 questions concerning food safety knowledge, handling practices, personal hygiene and basic health care, covering the stages when the food is under the control of the consumer, was developed and used to gather data for analysis. Appropriate scores were attributed to the questions (consequences to food safety and answers (likelihood of food contamination. A risk estimate algorithm and an appropriate risk ranking scale were used to assess the results. From August 2011 to March 2012, survey questionnaires were collected from 2,775 consumers in Brazil across 19 out of 27 state capitals. The study found risky practices with the potential to lead to food poisoning occurrences in the domestic environment in the following handling steps: food transportation, food preparation, cooking and the handling of leftovers. The personal hygiene, age, formal education, family income and basic health care habits represented the factors most related to the risky practices of consumers, which could orientate food safety educational campaigns for the Brazilian population.

  9. Bioremediation model for atrazine contaminated agricultural soils using phytoremediation (using Phaseolus vulgaris L.) and a locally adapted microbial consortium.

    Science.gov (United States)

    Madariaga-Navarrete, Alfredo; Rodríguez-Pastrana, Blanca Rosa; Villagómez-Ibarra, José Roberto; Acevedo-Sandoval, Otilio Arturo; Perry, Gregory; Islas-Pelcastre, Margarita

    2017-06-03

    The objective of the present study was to examine a biological model under greenhouse conditions for the bioremediation of atrazine contaminated soils. The model consisted in a combination of phytoremediation (using Phaseolus vulgaris L.) and rhizopheric bio-augmentation using native Trichoderma sp., and Rhizobium sp. microorganisms that showed no inhibitory growth at 10,000 mg L -1 of herbicide concentration. 33.3 mg of atrazine 50 g -1 of soil of initial concentration was used and an initial inoculation of 1 × 10 9 UFC mL -1 of Rhizobium sp. and 1 × 10 5 conidia mL -1 of Trichoderma sp. were set. Four treatments were arranged: Bean + Trichoderma sp. (B+T); Bean + Rhizobium sp. (BR); Bean + Rhizobium sp. + Trichoderma sp. (B+R+T) and Bean (B). 25.51 mg of atrazine 50 g -1 of soil (76.63%) was removed by the B+T treatment in 40 days (a = 0.050, Tukey). This last indicate that the proposed biological model and methodology developed is useful for atrazine contaminated bioremediation agricultural soils, which can contribute to reduce the effects of agrochemical abuse.

  10. Numerical modeling of the groundwater contaminant transport for the Lake Karachai Area: The methodological approach and the basic two- dimensional regional model

    International Nuclear Information System (INIS)

    Petrov, A.V.; Samsonova, L.M.; Vasil'kova, N.A.; Zinin, A.I.; Zinina, G.A.

    1994-06-01

    Methodological aspects of the numerical modeling of the groundwater contaminant transport for the Lake Karachay area are discussed. Main features of conditions of the task are the high grade of non-uniformity of the aquifer in the fractured rock massif and the high density of the waste solutions, and also the high volume of the input data: both on the part of parameters of the aquifer (number of pump tests) and on the part of observations of functions of processes (long-time observations by the monitoring well grid). The modeling process for constructing the two dimensional regional model is described, and this model is presented as the basic model for subsequent full three-dimensional modeling in sub-areas of interest. Original powerful mathematical apparatus and computer codes for finite-difference numerical modeling are used

  11. Numerical modeling of contaminant transport in fractured porous media using mixed finite-element and finitevolume methods

    KAUST Repository

    Dong, Chen

    2011-01-01

    A mathematical model for contaminant species passing through fractured porous media is presented. In the numerical model, we combine two locally conservative methods; i.e., the mixed finite-element (MFE) method and the finite-volume method. Adaptive triangle mesh is used for effective treatment of the fractures. A hybrid MFE method is employed to provide an accurate approximation of velocity fields for both the fractures and matrix, which are crucial to the convection part of the transport equation. The finite-volume method and the standard MFE method are used to approximate the convection and dispersion terms, respectively. The temporary evolution for the pressure distributions, streamline fields, and concentration profiles are obtained for six different arrangements of fractures. The results clearly show the distorted concentration effects caused by the ordered and disordered (random) patterns of the fractures and illustrate the robustness and efficiency of the proposed numerical model. © 2011 by Begell House Inc.

  12. Evidence for Legacy Contamination of Nitrate in Groundwater of North Carolina Using Monitoring and Private Well Data Models

    Science.gov (United States)

    Messier, K. P.; Kane, E.; Bolich, R.; Serre, M. L.

    2014-12-01

    Nitrate (NO3-) is a widespread contaminant of groundwater and surface water across the United States that has deleterious effects to human and ecological health. Legacy contamination, or past releases of NO3-, is thought to be impacting current groundwater and surface water of North Carolina. This study develops a model for predicting point-level groundwater NO3- at a state scale for monitoring wells and private wells of North Carolina. A land use regression (LUR) model selection procedure known as constrained forward nonlinear regression and hyperparameter optimization (CFN-RHO) is developed for determining nonlinear model explanatory variables when they are known to be correlated. Bayesian Maximum Entropy (BME) is then used to integrate the LUR model to create a LUR-BME model of spatial/temporal varying groundwater NO3- concentrations. LUR-BME results in a leave-one-out cross-validation r2 of 0.74 and 0.33 for monitoring and private wells, effectively predicting within spatial covariance ranges. The major finding regarding legacy sources NO3- in this study is that the LUR-BME models show the geographical extent of low-level contamination of deeper drinking-water aquifers is beyond that of the shallower monitoring well. Groundwater NO3- in monitoring wells is highly variable with many areas predicted above the current Environmental Protection Agency standard of 10 mg/L. Contrarily, the private well results depict widespread, low-level NO3-concentrations. This evidence supports that in addition to downward transport, there is also a significant outward transport of groundwater NO3- in the drinking water aquifer to areas outside the range of sources. Results indicate that the deeper aquifers are potentially acting as a reservoir that is not only deeper, but also covers a larger geographical area, than the reservoir formed by the shallow aquifers. Results are of interest to agencies that regulate surface water and drinking water sources impacted by the effects of

  13. Laboratory modeling, field study, and numerical simulation of bioremediation of petroleum contaminants

    International Nuclear Information System (INIS)

    Livingston, R.J.; Islam, M.R.

    1999-01-01

    The use of bioremediation as an alternative remediation technology is fast becoming the technique of choice among many environmental professionals. This method offers substantial benefits not found in other remediation processes. Bioremediation is very cost effective, nondestructive, relatively uncomplicated in implementing, requires nonspecialized equipment, and can be extremely effective in removing recalcitrant petroleum hydrocarbons. This study researched the availability of viable microbial populations in the arid climate in South Dakota. Exponential growth of the bacteria and the ability of bacteria to degrade long-chain hydrocarbons indicated that healthy populations do exist and could be used to mineralize organic hydrocarbons. Experimental results indicated that bioremediation can be effectively enhanced in landfills as well as in the subsurface using a supply of harmless nutrients. The biodegradation rate can be further enhanced with the use of edible surfactant that helped disperse the petroleum products. Also, the use of hydrogen peroxide enhanced the oxygen availability and increased the degradation rate. Interestingly, the bacterial growth rate was found to be high in difficult-to-biodegrade contaminants, such as waste oil. A numerical simulation program was also developed that describes the bacterial growth in the subsurface along with the reduction in substrate (contamination). Results from this program were found to be consistent with laboratory results

  14. Modeling of the stress-strain state of the ground mass contaminated with peracetic acid

    Directory of Open Access Journals (Sweden)

    Levenko Anna

    2017-01-01

    Full Text Available None of the methods described previously provides a solution to the problem that deals with the SSS evaluation of the ground mass which is under the influence of chemically active substances and, in particular, under the influence of peracetic acid. The stress-strain state of the ground mass contaminated with peracetic acid was estimated. Stresses occurring in the ground mass in the natural state were determined after the entry of acid into it and after the chemical fixation of it with sodium silicate. All the parameters of the stress-strain state of the ground mass were obtained under a number of physical and mechanical conditions. It was determined that following the work on the silicatization of the ground mass contaminated with peracetic acid the quantity of strain decreased by 26.11 to 48.9%. The comparison of the results of stress calculations indicates the stress reduction in the ground mass in 1.8 – 2.6 times after its fixing.

  15. STakeholder-Objective Risk Model (STORM): Determining the aggregated risk of multiple contaminant hazards in groundwater well catchments

    Science.gov (United States)

    Enzenhoefer, R.; Binning, P. J.; Nowak, W.

    2015-09-01

    Risk is often defined as the product of probability, vulnerability and value. Drinking water supply from groundwater abstraction is often at risk due to multiple hazardous land use activities in the well catchment. Each hazard might or might not introduce contaminants into the subsurface at any point in time, which then affects the pumped quality upon transport through the aquifer. In such situations, estimating the overall risk is not trivial, and three key questions emerge: (1) How to aggregate the impacts from different contaminants and spill locations to an overall, cumulative impact on the value at risk? (2) How to properly account for the stochastic nature of spill events when converting the aggregated impact to a risk estimate? (3) How will the overall risk and subsequent decision making depend on stakeholder objectives, where stakeholder objectives refer to the values at risk, risk attitudes and risk metrics that can vary between stakeholders. In this study, we provide a STakeholder-Objective Risk Model (STORM) for assessing the total aggregated risk. Or concept is a quantitative, probabilistic and modular framework for simulation-based risk estimation. It rests on the source-pathway-receptor concept, mass-discharge-based aggregation of stochastically occuring spill events, accounts for uncertainties in the involved flow and transport models through Monte Carlo simulation, and can address different stakeholder objectives. We illustrate the application of STORM in a numerical test case inspired by a German drinking water catchment. As one may expect, the results depend strongly on the chosen stakeholder objectives, but they are equally sensitive to different approaches for risk aggregation across different hazards, contaminant types, and over time.

  16. KINETIC MODELLING AND HALF LIFE STUDY OF ADSORPTIVE BIOREMEDIATION OF SOIL ARTIFICIALLY CONTAMINATED WITH BONNY LIGHT CRUDE OIL

    Directory of Open Access Journals (Sweden)

    Samuel Enahoro Agarry

    2015-06-01

    Full Text Available In this study, comparative potential effects of commercial activated carbon (CAC and plantain peel-derived biochar (PPBC of different particle sizes and dosage to stimulate petroleum hydrocarbon biodegradation in soil were investigated. Microcosms containing soil were spiked with weathered Bonny light crude oil (WBLCO (10% w/w and amended with different particle sizes (0.02, 0.07 and 0.48 mm and dosage (20, 30 and 40 g of CAC and PPBC, respectively. The bioremediation experiments were carried out for a period of 28 days under laboratory conditions. The results showed that there was a positive relationship between the rate of petroleum hydrocarbons reduction and presence of the CAC and PPBC in crude oil contaminated soil microcosms. The WBLCO biodegradation data fitted well to the first-order kinetic model. The model revealed that WBLCO contaminated-soil microcosms amended with CAC and PPBC had higher biodegradation rate constants (k as well as lower half-life times (t1/2 than unamended soil (natural attenuation remediation system. The rate constants increased while half-life times decreased with decreased particle size and increased dosage of amendment agents. ANOVA statistical analysis revealed that WBLCO biodegradation in soil was significantly (p = 0.05 influenced by the addition of CAC and biochar amendment agents, respectively. However, Tukey’s post hoc test (at p = 0.05 showed that there was no significant difference in the bioremediation efficiency of CAC and PPBC. Thus, amendment of soils with biochar has the potential to be an inexpensive, efficient, environmentally friendly and relatively novel strategy to mitigate organic compound-contaminated soil.

  17. Local scale marine modelling of Fukushima releases. Assessment of water and sediment contamination and sensitivity to water circulation description

    International Nuclear Information System (INIS)

    Periáñez, R.; Suh, Kyung-Suk; Min, Byung-Il

    2012-01-01

    Highlights: ► First simulations of Cs seabed sediment contamination after Fukushima releases. ► Effects of tides on dispersion patterns assessed: not significant. ► Two kinetic models for uptake/release reactions compared. ► Daily currents from two ocean models have been used. Results compared. ► Overall better results with JCOPE2 currents and 2-step kinetics. - Abstract: The dispersion of 137 Cs released from Fukushima nuclear power plant to the sea after the March 11th 2011 tsunami has been studied using numerical models. The 3D dispersion model consists of an advection/diffusion equation with terms describing uptake/release reactions between water and seabed sediments. The dispersion model has been fed with daily currents provided by HYCOM and JCOPE2 ocean models. Seabed sediment 137 Cs patterns obtained using both current data set have been compared. The impact of tides and of atmospheric deposition has been evaluated as well. It has been also found that a 2-step kinetic model (two consecutive reversible reactions) for describing water/sediment interactions produces better results than a 1-step model (one single reversible reaction).

  18. Evaluation of a cross contamination model describing transfer of Salmonella spp. and Listeria monocytogenes during grinding of pork and beef.

    Science.gov (United States)

    Møller, C O A; Sant'Ana, A S; Hansen, S K H; Nauta, M J; Silva, L P; Alvarenga, V O; Maffei, D; Silva, F F P; Lopes, J T; Franco, B D G M; Aabo, S; Hansen, T B

    2016-06-02

    In a previous study, a model was developed to describe the transfer and survival of Salmonella during grinding of pork (Møller, C.O.A., Nauta, M.J., Christensen, B.B., Dalgaard, P., Hansen, T.B., 2012. Modelling transfer of Salmonella typhimurium DT104 during simulation of grinding of pork. Journal of Applied Microbiology 112 (1), 90-98). The robustness of this model is now evaluated by studying its performance for predicting the transfer and survival of Salmonella spp. and Listeria monocytogenes during grinding of different types of meat (pork and beef), using two different grinders, different sizes and different numbers of pieces of meats to be ground. A total of 19 grinding trials were collected. Acceptable Simulation Zone (ASZ), visual inspection of the data, Quantitative Microbiological Risk Assessment (QMRA), as well as the Total Transfer Potential (TTP) were used as approaches to evaluate model performance and to access the quality of the cross contamination model predictions. Using the ASZ approach and considering that 70% of the observed counts have to be inside a defined acceptable zone of ±0.5 log10CFU per portion, it was found that the cross contamination parameters suggested by Møller et al. (2012) were not able to describe all 19 trials. However, for each of the collected grinding trials, the transfer event was well described when fitted to the model structure proposed by Møller et al. (2012). Parameter estimates obtained by fitting observed trials performed at different conditions, such as size and number of pieces of meat to be ground, may not be applied to describe cross contamination of unlike processing. Nevertheless, the risk estimates, as well as the TTP, revealed that the risk of disease may be reduced when the grinding of meat is performed in a grinder made of stainless steel (for all surfaces in contact with the meat), using a well-sharpened knife and holding at room temperatures lower than 4°C. Copyright © 2016 Elsevier B.V. All

  19. Modeling retrospective attribution of responsibility to hazard-managing institutions: an example involving a food contamination incident.

    Science.gov (United States)

    Johnson, Branden B; Hallman, William K; Cuite, Cara L

    2015-03-01

    Perceptions of institutions that manage hazards are important because they can affect how the public responds to hazard events. Antecedents of trust judgments have received far more attention than antecedents of attributions of responsibility for hazard events. We build upon a model of retrospective attribution of responsibility to individuals to examine these relationships regarding five classes of institutions that bear responsibility for food safety: producers (e.g., farmers), processors (e.g., packaging firms), watchdogs (e.g., government agencies), sellers (e.g., supermarkets), and preparers (e.g., restaurants). A nationally representative sample of 1,200 American adults completed an Internet-based survey in which a hypothetical scenario involving contamination of diverse foods with Salmonella served as the stimulus event. Perceived competence and good intentions of the institution moderately decreased attributions of responsibility. A stronger factor was whether an institution was deemed (potentially) aware of the contamination and free to act to prevent or mitigate it. Responsibility was rated higher the more aware and free the institution. This initial model for attributions of responsibility to impersonal institutions (as opposed to individual responsibility) merits further development. © 2014 Society for Risk Analysis.

  20. A mouse model of cytogenetic analysis to evaluate caesium137 radiation dose exposure and contamination level in lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Roch-Lefevre, Sandrine; Martin-Bodiot, Cecile; Gregoire, Eric; Roy, Laurence [Institut de Radioprotection et de Surete Nucleaire (IRSN), Laboratoire de Dosimetrie Biologique (PRP-HOM/SRBE/LDB), Fontenay aux Roses Cedex (France); Desbree, Aurelie [Institut de Radioprotection et de Surete Nucleaire (IRSN), PRP-HOM/SDI, Laboratoire d' Evaluation de la Dose Interne, Fontenay aux Roses Cedex (France); Barquinero, Joan Francesc [Institut de Radioprotection et de Surete Nucleaire (IRSN), Laboratoire de Dosimetrie Biologique (PRP-HOM/SRBE/LDB), Fontenay aux Roses Cedex (France); Universitat Autonoma de Barcelona, Unitat d' Antropologia Biologica, Departament de Biologia Animal, Biologia Vegetal i Ecologia, Bellaterra (Spain)

    2016-03-15

    In case of external overexposure to ionizing radiation, an estimation of its genotoxic effects on exposed individuals can be made retrospectively by the measurement of radiation-induced chromosome aberrations on circulating lymphocytes. Compared with external irradiation, intakes of radionuclides may, however, lead to specific features influencing dose distribution at the scale of body, of tissue or even of cell. Therefore, in case of internal contamination by radionuclides, experimental studies, particularly using animal models, are required to better understand mechanisms of their genotoxic effects and to better estimate the absorbed dose. The present study was designed to evaluate a cytogenetic method in mouse peripheral blood lymphocytes that would allow determination of yields and complexities of chromosome aberrations after low-dose rate exposure to {sup 137}Cs delivered in vitro either by irradiation or by contamination. By using M-FISH analysis, we compared the low-dose rate responses observed in mouse to the high-dose rate responses observed both in mouse and in human. Promising similarities between the two species in the relative biological effect evaluation show that our cytogenetic model established in mouse might be useful to evaluate various radiation exposures, particularly relevant in case of intakes of radionuclides. (orig.)

  1. Modeling of steroid estrogen contamination in UK and South Australian rivers predicts modest increases in concentrations in the future.

    Science.gov (United States)

    Green, Christopher; Williams, Richard; Kanda, Rakesh; Churchley, John; He, Ying; Thomas, Shaun; Goonan, Peter; Kumar, Anu; Jobling, Susan

    2013-07-02

    The prediction of risks posed by pharmaceuticals and personal care products in the aquatic environment now and in the future is one of the top 20 research questions regarding these contaminants following growing concern for their biological effects on fish and other animals. To this end it is important that areas experiencing the greatest risk are identified, particularly in countries experiencing water stress, where dilution of pollutants entering river networks is more limited. This study is the first to use hydrological models to estimate concentrations of pharmaceutical and natural steroid estrogens in a water stressed catchment in South Australia alongside a UK catchment and to forecast their concentrations in 2050 based on demographic and climate change predictions. The results show that despite their differing climates and demographics, modeled concentrations of steroid estrogens in effluents from Australian sewage treatment works and a receiving river were predicted (simulated) to be similar to those observed in the UK and Europe, exceeding the combined estradiol equivalent's predicted no effect concentration for feminization in wild fish. Furthermore, by 2050 a moderate increase in estrogenic contamination and the potential risk to wildlife was predicted with up to a 2-fold rise in concentrations.

  2. Laboratory modeling, field study, and numerical simulation of bioremediation of petroleum contaminants

    International Nuclear Information System (INIS)

    Livingston, R.J.; Islam, M.R.

    1999-01-01

    Historical methods of cleaning up petroleum hydrocarbons from the vadose zone, the capillary zone, and the aquifers are not technically true cleanup technologies but rather transfer techniques. In addition, environmental engineers are realizing that the standard remediation techniques are not entirely effective in removing the hazardous material in a reasonable time frame. Long-chain hydrocarbons such as kerosene, diesel, and waste oil are particularly difficult to remediate using conventional techniques. The use of bioremediation as an alternative remediation technology is fast becoming the technique of choice among many environmental professionals. This method offers substantial benefits not found in other remediation processes. Bioremediation is very cost effective, nondestructive, relatively uncomplicated in implementing, requires non specialized equipment, and can be extremely effective in removing recalcitrant petroleum hydrocarbons. This study researched the availability of viable microbial populations in the arid climate in South Dakota. Exponential growth of the bacteria and the ability of bacteria to degrade long-chain hydrocarbons indicated that healthy populations do exist and could be used to mineralize organic hydrocarbons. Experimental results indicated that bioremediation can be effectively enhanced in landfills as well as in the subsurface using a supply of harmless nutrients. The biodegradation rate can be further enhanced with the use of edible surfactant that helped disperse the petroleum products. Also, the use of hydrogen peroxide enhanced the oxygen availability and increased the degradation rate. Interestingly, the bacterial growth rate is found to be high in difficult-to-biodegrade contaminants, such as waste oil. A numerical simulation program was also developed that describes the bacterial growth in the subsurface along with the reduction in substrate (contamination). Results from this program were found to be consistent with laboratory

  3. A model for evaluating the three-dimensional groundwater dividing pathline between a contaminant source and a partially penetrating water-supply well

    Science.gov (United States)

    Harmsen, Eric W.; Converse, James C.; Anderson, Mary P.; Hoopes, John A.

    1991-09-01

    Effluent from septic tank-drainfields can degrade groundwater quality and contaminate nearby water-supply wells. Such groundwater contamination is a problem in the unsewered subdivisions of the sand plain of central Wisconsin, for example. To help planners minimize the risk of direct contamination of a water-supply well by a septic system, a model was developed to estimate the location of the critical dividing pathline between a rectangular contaminant source (the septic tank drainfield) and a partially penetrating pumping well. The model is capable of handling three-dimensional, transient flow in an unconfined, homogeneous, anisotropic aquifer of infinite areal extent, under a regional horizontal hydraulic gradient. Model results are in very good agreement with several other numerical and analytical models. Examples are given for which the safe, horizontal and vertical separation distances to avoid well water contamination are determined for typical central Wisconsin sand plain conditions. A companion paper (Harmsen et al., 1991) describes the application of this model, using a Monte-Carlo analysis, to study the variation of these separation distances in the Wisconsin sand plain. The model can also be applied to larger scale problems and, therefore, could be useful in implementing the U.S. Environmental Protection Agency's new well head protection program.

  4. Modeling the photodegradation of emerging contaminants in waters by UV radiation and UV/H2O2 system.

    Science.gov (United States)

    Benitez, F Javier; Acero, Juan L; Real, Francisco J; Roldan, Gloria; Rodriguez, Elena

    2013-01-01

    Five emerging contaminants (1-H-Benzotriazole, N,N-diethyl-m-toluamide or DEET, Chlorophene, 3-Methylindole, and Nortriptyline HCl), frequently found in surface waters and wastewaters, were selected to be photooxidized in several water matrices. Previous degradation experiments of these compounds individually dissolved in ultra pure water were performed by using UV radiation at 254 nm and the Fenton's reagent. These oxidation systems allowed the determination of the quantum yields and the rate constants for the radical reaction between each compound and hydroxyl radicals. Later, the simultaneous photodegradation of mixtures of the selected ECs in several types of water (ultrapure water, reservoir water, and two effluents from WWTPs) was carried out and a kinetic study was conducted. A model is proposed for the ECs elimination, and the theoretically calculated concentrations with this model agreed well with the experimental results obtained, which confirmed that it constitutes an excellent tool to predict the elimination of these compounds in waters.

  5. MODELING THE ANOMALY OF SURFACE NUMBER DENSITIES OF GALAXIES ON THE GALACTIC EXTINCTION MAP DUE TO THEIR FIR EMISSION CONTAMINATION

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwagi, Toshiya; Suto, Yasushi; Taruya, Atsushi; Yahata, Kazuhiro [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Kayo, Issha [Department of Physics, Toho University, Funabashi, Chiba 274-8510 (Japan); Nishimichi, Takahiro, E-mail: kashiwagi@utap.phys.s.u-tokyo.ac.jp [Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan)

    2015-02-01

    The most widely used Galactic extinction map is constructed assuming that the observed far-infrared (FIR) fluxes come entirely from Galactic dust. According to the earlier suggestion by Yahata et al., we consider how FIR emission of galaxies affects the SFD map. We first compute the surface number density of Sloan Digital Sky Survey (SDSS) DR7 galaxies as a function of the r-band extinction, A {sub r,} {sub SFD}. We confirm that the surface densities of those galaxies positively correlate with A {sub r,} {sub SFD} for A {sub r,} {sub SFD} < 0.1, as first discovered by Yahata et al. for SDSS DR4 galaxies. Next we construct an analytical model to compute the surface density of galaxies, taking into account the contamination of their FIR emission. We adopt a log-normal probability distribution for the ratio of 100 μm and r-band luminosities of each galaxy, y ≡ (νL){sub 100} {sub μm}/(νL) {sub r}. Then we search for the mean and rms values of y that fit the observed anomaly, using the analytical model. The required values to reproduce the anomaly are roughly consistent with those measured from the stacking analysis of SDSS galaxies. Due to the limitation of our statistical modeling, we are not yet able to remove the FIR contamination of galaxies from the extinction map. Nevertheless, the agreement with the model prediction suggests that the FIR emission of galaxies is mainly responsible for the observed anomaly. Whereas the corresponding systematic error in the Galactic extinction map is 0.1-1 mmag, it is directly correlated with galaxy clustering and thus needs to be carefully examined in precision cosmology.

  6. Assessment of the consequences of the radioactive contamination of aquatic media and biota. Model testing using Chernobyl data

    International Nuclear Information System (INIS)

    Kryshev, I.; Sazykina, T.; Hoffman, O.; Thiessen, K.

    1996-09-01

    The 'Cooling Pond' scenario was designed to test models for radioactive contamination of aquatic ecosystems, based on data for contamination of different aquatic media and biota due to fallout of radionuclides into the cooling pond of the Chernobyl Nuclear Power Plant. Input data included characteristics of the cooling pond ecosystem (hydrological, hydrochemical, and hydro biological conditions) and estimates of the amounts of 137 Cs in the cooling pond. Predictions were requested in two stages: (1) Calculations of 137 Cs concentrations for comparison against actual measurements, including activities of 137 Cs in the cooling pond water, in layers of sediment, and in fish; (2) Calculations for which actual measurements are not available, including dose and risk estimates for aquatic biota and for humans following hypothetical consumption of contaminated biota. Calculations were performed with the following models: LAKECO (Netherlands), POSOD (USA), LAKEPOND (Romania), WATER (Russia), GIDRO (Russia), and ECOMOD-W (Russia). The total number of scenario calculations was 18. In general, the models tended to overestimate the total doses to fish (as compared to to independent dose estimates made from measured concentrations by the scenario authors) for internal and external exposure, while a number of predictions with different models for the effective dose and risk to humans from fish consumption were in good agreement with independent test estimates. The differences among model predictions were somewhat smaller for the total doses to fish than for the environmental concentrations used in the model testing. The differences among model predictions were very great for the effective doses and risk to humans from fish consumption. This is related to distinct errors in assessments of 137 Cs concentrations in fish. Very few participants obtained good agreement with respect to all criteria of the model testing, i.e., 137 Cs concentrations in the aquatic ecosystem components and

  7. Assessment of the consequences of the radioactive contamination of aquatic media and biota. Model testing using Chernobyl data

    Energy Technology Data Exchange (ETDEWEB)

    Kryshev, I.; Sazykina, T. [SPA Typhoon, Obninsk (Russian Federation); Hoffman, O.; Thiessen, K. [SENES, Oak Ridge, TN (United States)] [and others

    1996-09-01

    The 'Cooling Pond' scenario was designed to test models for radioactive contamination of aquatic ecosystems, based on data for contamination of different aquatic media and biota due to fallout of radionuclides into the cooling pond of the Chernobyl Nuclear Power Plant. Input data included characteristics of the cooling pond ecosystem (hydrological, hydrochemical, and hydro biological conditions) and estimates of the amounts of 137 Cs in the cooling pond. Predictions were requested in two stages: (1) Calculations of 137 Cs concentrations for comparison against actual measurements, including activities of 137 Cs in the cooling pond water, in layers of sediment, and in fish; (2) Calculations for which actual measurements are not available, including dose and risk estimates for aquatic biota and for humans following hypothetical consumption of contaminated biota. Calculations were performed with the following models: LAKECO (Netherlands), POSOD (USA), LAKEPOND (Romania), WATER (Russia), GIDRO (Russia), and ECOMOD-W (Russia). The total number of scenario calculations was 18. In general, the models tended to overestimate the total doses to fish (as compared to to independent dose estimates made from measured concentrations by the scenario authors) for internal and external exposure, while a number of predictions with different models for the effective dose and risk to humans from fish consumption were in good agreement with independent test estimates. The differences among model predictions were somewhat smaller for the total doses to fish than for the environmental concentrations used in the model testing. The differences among model predictions were very great for the effective doses and risk to humans from fish consumption. This is related to distinct errors in assessments of 137 Cs concentrations in fish. Very few participants obtained good agreement with respect to all criteria of the model testing, i.e., 137 Cs concentrations in the aquatic ecosystem

  8. Model for Estimating Acute Health Impacts from Consumption of Contaminated Drinking Water

    Science.gov (United States)

    This journal article discusses disease transmission models used to predict the spread of disease over time through susceptible, infected and recoverred populations, commonly used to design public intervention strategies. Amodified disease model is linked to flow and transport mod...

  9. Engineering and environmental remediation scenarios due to leakage from the Gulf War oil spill using 3-D numerical contaminant modellings

    Science.gov (United States)

    Yihdego, Yohannes; Al-Weshah, Radwan A.

    2017-11-01

    The transport groundwater modelling has been undertaken to assess potential remediation scenarios and provide an optimal remediation options for consideration. The purpose of the study was to allow 50 years of predictive remediation simulation time. The results depict the likely total petroleum hydrocarbon migration pattern in the area under the worst-case scenario. The remediation scenario simulations indicate that do nothing approach will likely not achieve the target water quality within 50 years. Similarly, complete source removal approach will also likely not achieve the target water quality within 50 years. Partial source removal could be expected to remove a significant portion of the contaminant mass, but would increase the rate of contaminant recharge in the short to medium term. The pump-treat-reinject simulation indicates that the option appears feasible and could achieve a reduction in the area of the 0.01 mg/L TPH contour area for both Raudhatain and Umm Al-Aish by 35 and 30%, respectively, within 50 years. The rate of improvement and the completion date would depend on a range of factors such as bore field arrangements, pumping rates, reinjection water quality and additional volumes being introduced and require further optimisation and field pilot trials.

  10. On the significance of contaminant plume-scale and dose-response models in defining hydrogeological characterization needs

    Science.gov (United States)

    de Barros, F.; Rubin, Y.; Maxwell, R.; Bai, H.

    2007-12-01

    Defining rational and effective hydrogeological data acquisition strategies is of crucial importance since financial resources available for such efforts are always limited. Usually such strategies are developed with the goal of reducing uncertainty, but less often they are developed in the context of the impacts of uncertainty. This paper presents an approach for determining site characterization needs based on human health risk factors. The main challenge is in striking a balance between improved definition of hydrogeological, behavioral and physiological parameters. Striking this balance can provide clear guidance on setting priorities for data acquisition and for better estimating adverse health effects in humans. This paper addresses this challenge through theoretical developments and numerical testing. We will report on a wide range of factors that affect the site characterization needs including contaminant plume's dimensions, travel distances and other length scales that characterize the transport problem, as well as health risk models. We introduce a new graphical tool that allows one to investigate the relative impact of hydrogeological and physiological parameters in risk. Results show that the impact of uncertainty reduction in the risk-related parameters decreases with increasing distances from the contaminant source. Also, results indicate that human health risk becomes less sensitive to hydrogeological measurements when dealing with ergodic plumes. This indicates that under ergodic conditions, uncertainty reduction in human health risk may benefit from better understanding of the physiological component as opposed to a detailed hydrogeological characterization

  11. Biosphere modelling for safety assessment of geological disposal taking account of denudation of contaminated soils. Research document

    International Nuclear Information System (INIS)

    Kato, Tomoko

    2003-03-01

    Biosphere models for safety assessment of geological disposal have been developed on the assumption that the repository-derived radionuclides reach surface environment by groundwater. In the modelling, river, deep well and marine have been considered as geosphere-biosphere (GBIs) and some Japanese-specific ''reference biospheres'' have been developed using an approach consistent with the BIOMOVS II/BIOMASS Reference Biosphere Methodology. In this study, it is assumed that the repository-derived radionuclide would reach surface environment in the form of solid phase by uplift and erosion of contaminated soil and sediment. The radionuclides entered into the surface environment by these processes could be distributed between solid and liquid phases and could spread within the biosphere via solid phase and also liquid phase. Based on these concepts, biosphere model that considers variably saturated zone under surface soil (VSZ) as a GBI was developed for calculating the flux-to-dose conversion factors of three exposure groups (farming, freshwater fishing, marine fishing) based on the Reference Biosphere Methodology. The flux-to-dose conversion factors for faming exposure group were the highest, and ''inhalation of dust'', external irradiation from soil'' and ''ingestion of soil'' were the dominant exposure pathways for most of radionuclides considered in this model. It is impossible to compare the flux-to-dose conversion factors calculated by the biosphere model in this study with those calculated by the biosphere models developed in the previous studies because the migration processes considered when the radionuclides entered the surface environment through the aquifer are different among the models; i.e. it has been assumed that the repository-derived radionuclides entered the GBIs such as river, deep well and marine via groundwater without dilution and retardation at the aquifer in the previous biosphere models. Consequently, it must be modelled the migration of

  12. Model of contamination sources of electron for radiotherapy of beams of photons

    International Nuclear Information System (INIS)

    Gonzalez Infantes, W.; Lallena Rojo, A. M.; Anguiano Millan, M.

    2013-01-01

    Proposes a model of virtual sources of electrons, that allows to reproduce the sources to the input parameters of the representation of the patient. To compare performance in depth values and calculated profiles from the full simulation of the heads, with the calculated values using sources model, found that the model is capable of playing depth dose distributions and profiles. (Author)

  13. Modeling of Cr contamination in the agricultural lands of three villages near the leather industry in Kasur, Pakistan, using statistical and GIS techniques.

    Science.gov (United States)

    Shafiq, Muhammad; Shaukat, Tahira; Nazir, Aisha; Bareen, Firdaus-E-

    2017-08-01

    Kasur is one of the hubs of leather industry in the Punjab, Pakistan, where chrome tanning method of leather processing is extensively being used. Chromium (Cr) accumulation levels in the irrigation water, soil, and seasonal vegetables were studied in three villages located in the vicinity of wastewater treatment plant and solid waste dumping site operated by the Kasur Tanneries Waste Management Agency (KTWMA). The data was interpreted using analysis of variance (ANOVA), clustering analysis (CA), and principal component analysis (PCA). Interpolated surface maps for Cr were generated using the actual data obtained for the 30 sampling sites in each of the three villages for irrigation water, soil, and seasonal vegetables. The level of contamination in the three villages was directly proportional to their distance from KTWMA wastewater treatment plant and the direction of water runoff. The highest level of Cr contamination in soil (mg kg -1 ) was observed at Faqeeria Wala (37.67), intermediate at Dollay Wala (30.33), and the least in Maan (25.16). A gradational variation in Cr accumulation was observed in the three villages from contaminated wastewater having the least contamination level (2.02-4.40 mg L -1 ), to soil (25.16-37.67 mg kg -1 ), and ultimately in the seasonal vegetable crops (156.67-248.33 mg kg -1 ) cultivated in the region, having the highest level of Cr contamination above the permissible limit. The model used not only predicted the current situation of Cr contamination in the three villages but also indicated the trend of magnification of Cr contamination from irrigation water to soil and to the base of the food chain. Among the multiple causes of Cr contamination of vegetables, soil irrigation with contaminated groundwater was observed to be the dominant one.

  14. Direct and indirect effects of copper-contaminated sediments on the functions of model freshwater ecosystems.

    Science.gov (United States)

    Gardham, Stephanie; Chariton, Anthony A; Hose, Grant C

    2015-01-01

    Copper is acutely toxic to, and directly affects, primary producers and decomposers, which are key players in essential processes such as the nutrient cycle in freshwater ecosystems. Even though the indirect effects of metals (for example effects due to changes in species interactions) may be more common than direct effects, little is known about the indirect effects of copper on primary producers and decomposers. The effects of copper on phytoplankton, macrophytes, periphyton and organic matter decomposition in an outdoor lentic mesocosm facility were assessed, and links between the responses examined. Copper directly decreased macrophyte growth, subsurface organic matter decomposition, and the potential for high phytoplankton Chlorophyll a concentrations. However, periphyton cover and organic matter decomposition on the surface of the sediment were stimulated by the presence of copper. These latter responses were attributed to indirect effects, due to a reduction in grazing pressure from snails, particularly Physa acuta, in the higher copper-contaminated mesocosms. This permitted the growth of periphyton and other heterotrophs, ultimately increasing decomposition at the sediment surface. The present study demonstrates the pronounced influence indirect effects may have on ecological function, findings that may not be observed in traditional laboratory studies (which utilize single species or simplistic communities).

  15. Predictive geochemical modeling of contaminant concentrations in laboratory columns and in plumes migrating from uranium mill tailings waste impoundments

    International Nuclear Information System (INIS)

    Peterson, S.R.; Martin, W.J.; Serne, R.J.

    1986-04-01

    A computer-based conceptual chemical model was applied to predict contaminant concentrations in plumes migrating from a uranium mill tailings waste impoundment. The solids chosen for inclusion in the conceptual model were selected based on reviews of the literature, on ion speciation/solubility calculations performed on the column effluent solutions and on mineralogical characterization of the contacted and uncontacted sediments. The mechanism of adsorption included in the conceptual chemical model was chosen based on results from semiselective extraction experiments and from mineralogical characterization procedures performed on the sediments. This conceptual chemical model was further developed and partially validated in laboratory experiments where assorted acidic uranium mill tailings solutions percolated through various sediments. This document contains the results of a partial field and laboratory validation (i.e., test of coherence) of this chemical model. Macro constituents (e.g., Ca, SO 4 , Al, Fe, and Mn) of the tailings solution were predicted closely by considering their concentrations to be controlled by the precipitation/dissolution of solid phases. Trace elements, however, were generally predicted to be undersaturated with respect to plausible solid phase controls. The concentration of several of the trace elements were closely predicted by considering their concentrations to be controlled by adsorption onto the amorphous iron oxyhydroxides that precipitated

  16. Geochemical modeling of reactions and partitioning of trace metals and radionuclides during titration of contaminated acidic sediments.

    Science.gov (United States)

    Zhang, Fan; Luo, Wensui; Parker, Jack C; Spalding, Brian P; Brooks, Scott C; Watson, David B; Jardine, Philip M; Gu, Baohua

    2008-11-01

    Many geochemical reactions that control aqueous metal concentrations are directly affected by solution pH. However, changes in solution pH are strongly buffered by various aqueous phase and solid phase precipitation/dissolution and adsorption/desorption reactions. The ability to predict acid-base behavior of the soil-solution system is thus critical to predict metal transport under variable pH conditions. This studywas undertaken to develop a practical generic geochemical modeling approach to predict aqueous and solid phase concentrations of metals and anions during conditions of acid or base additions. The method of Spalding and Spalding was utilized to model soil buffer capacity and pH-dependent cation exchange capacity by treating aquifer solids as a polyprotic acid. To simulate the dynamic and pH-dependent anion exchange capacity, the aquifer solids were simultaneously treated as a polyprotic base controlled by mineral precipitation/ dissolution reactions. An equilibrium reaction model that describes aqueous complexation, precipitation, sorption and soil buffering with pH-dependent ion exchange was developed using HydroGeoChem v5.0 (HGC5). Comparison of model results with experimental titration data of pH, Al, Ca, Mg, Sr, Mn, Ni, Co, and SO4(2-) for contaminated sediments indicated close agreement suggesting that the model could potentially be used to predictthe acid-base behavior of the sediment-solution system under variable pH conditions.

  17. Simulating the dynamics of polycyclic aromatic hydrocarbon (PAH) in contaminated soil through composting by COP-Compost model.

    Science.gov (United States)

    Zhang, Yuan; Guan, Yidong; Shi, Qi

    2015-02-01

    Organic pollutants (OPs) are potentially present in composts, and the assessment of their content and bioaccessibility in these composts is of paramount importance to minimize the risk of soil contamination and improve soil fertility. In this work, integration of the dynamics of organic carbon (OC) and OPs in an overall experimental framework is first proposed and adopted to validate the applicability of the COP-Compost model and to calibrate the model parameters on the basis of what has been achieved with the COP-Compost model. The COP-Compost model was evaluated via composting experiments containing 16 US Environmental Protection Agency (USEPA) polycyclic aromatic hydrocarbons (PAHs) and the sorption coefficient (Kd) values of two types of OP: fluorenthene (FLT) and pyrene (PHE). In our study, these compounds are used to characterize the sequential extraction and are quantified as soluble, sorbed, and non-extractable fractions. The model was calibrated, and coupling the OC and OP modules improved the simulation of the OP behavior and bioaccessibility during composting. The results show good agreement between the simulated and experimental results describing the evolution of different organic pollutants using the OP module, as well as the coupling module. However, no clear relationship is found between the Kd and the property of organic fractions. Further estimation of parameters is still necessary to modify the insufficiency of this present research.

  18. Code-To-Code Benchmarking Of The Porflow And GoldSim Contaminant Transport Models Using A Simple 1-D Domain - 11191

    International Nuclear Information System (INIS)

    Hiergesell, R.; Taylor, G.

    2010-01-01

    An investigation was conducted to compare and evaluate contaminant transport results of two model codes, GoldSim and Porflow, using a simple 1-D string of elements in each code. Model domains were constructed to be identical with respect to cell numbers and dimensions, matrix material, flow boundary and saturation conditions. One of the codes, GoldSim, does not simulate advective movement of water; therefore the water flux term was specified as a boundary condition. In the other code, Porflow, a steady-state flow field was computed and contaminant transport was simulated within that flow-field. The comparisons were made solely in terms of the ability of each code to perform contaminant transport. The purpose of the investigation was to establish a basis for, and to validate follow-on work that was conducted in which a 1-D GoldSim model developed by abstracting information from Porflow 2-D and 3-D unsaturated and saturated zone models and then benchmarked to produce equivalent contaminant transport results. A handful of contaminants were selected for the code-to-code comparison simulations, including a non-sorbing tracer and several long- and short-lived radionuclides exhibiting both non-sorbing to strongly-sorbing characteristics with respect to the matrix material, including several requiring the simulation of in-growth of daughter radionuclides. The same diffusion and partitioning coefficients associated with each contaminant and the half-lives associated with each radionuclide were incorporated into each model. A string of 10-elements, having identical spatial dimensions and properties, were constructed within each code. GoldSim's basic contaminant transport elements, Mixing cells, were utilized in this construction. Sand was established as the matrix material and was assigned identical properties (e.g. bulk density, porosity, saturated hydraulic conductivity) in both codes. Boundary conditions applied included an influx of water at the rate of 40 cm/yr at one

  19. Modeling of geo-material durability and contaminant fate in recycling or disposal of industrial and radioactive waste

    International Nuclear Information System (INIS)

    De Windt, L.

    2011-01-01

    This report deals with the HYTEC model, coupling chemical and hydrodynamic processes, and its application to the recycling of inorganic wastes and the disposal of hazardous and radioactive wastes. A common feature is the assessment of geo-material durability while submitted to chemical disturbances by their industrial or natural environment and, reciprocally, the quantification of contaminant fate in soils and aquifers. Research papers in a first section numerically oriented, HYTEC is validated by means of an intercomparison exercise based on oxidative UO 2 dissolution and the subsequent migration of U species in subsurface environments. A numerical approach of leaching tests is also discussed. Several researches based on HYTEC follows. The evolution of the cement/clay interface is simulated in the framework of the multi-barrier system of radioactive waste disposal and the Tournemire engineering analog; discriminating between the physical and chemical key processes. The physico-chemical processes of cement biodegradation by fungi are investigated with a focus on acidic hydrolysis and complexation by biogenic carboxylic acids. Modeling of source-terms and ageing with respect to contaminant migration is discussed in the case of the chemical alteration of spent fuel pellets under disposal conditions by considering radiolytic dissolution, inhibiting effect and radioactive decay, and by analyzing the effect of fractures on the containment properties of subsurface disposal facilities of stabilized/solidified waste. Leaching lab experiments applied to steel slag and the chemical evolution of leachate from MSWI sub-bases of two pilot roads over 10 years are eventually modelled to better estimate the environmental impact of such recycling scenarios. On-going research In the straight lines of the modeling of radioactive waste disposal, a first perspective is to investigate the transient states driven by thermal gradient and water re-saturation of the near-field barriers and

  20. Effects of natural and human factors on groundwater quality of basin-fill aquifers in the southwestern United States-conceptual models for selected contaminants

    Science.gov (United States)

    Bexfield, Laura M.; Thiros, Susan A.; Anning, David W.; Huntington, Jena M.; McKinney, Tim S.

    2011-01-01

    As part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program, the Southwest Principal Aquifers (SWPA) study is building a better understanding of the factors that affect water quality in basin-fill aquifers in the Southwestern United States. The SWPA study area includes four principal aquifers of the United States: the Basin and Range basin-fill aquifers in California, Nevada, Utah, and Arizona; the Rio Grande aquifer system in New Mexico and Colorado; and the California Coastal Basin and Central Valley aquifer systems in California. Similarities in the hydrogeology, land- and water-use practices, and water-quality issues for alluvial basins within the study area allow for regional analysis through synthesis of the baseline knowledge of groundwater-quality conditions in basins previously studied by the NAWQA Program. Resulting improvements in the understanding of the sources, movement, and fate of contaminants are assisting in the development of tools used to assess aquifer susceptibility and vulnerability.This report synthesizes previously published information about the groundwater systems and water quality of 15 information-rich basin-fill aquifers (SWPA case-study basins) into conceptual models of the primary natural and human factors commonly affecting groundwater quality with respect to selected contaminants, thereby helping to build a regional understanding of the susceptibility and vulnerability of basin-fill aquifers to those contaminants. Four relatively common contaminants (dissolved solids, nitrate, arsenic, and uranium) and two contaminant classes (volatile organic compounds (VOCs) and pesticide compounds) were investigated for sources and controls affecting their occurrence and distribution above specified levels of concern in groundwater of the case-study basins. Conceptual models of factors that are important to aquifer vulnerability with respect to those contaminants and contaminant classes were subsequently formed. The

  1. GWSCREEN: A semi-analytical model for assessment of the groundwater pathway from surface or buried contamination: Version 2.0 theory and user's manual

    International Nuclear Information System (INIS)

    Rood, A.S.

    1993-06-01

    GWSCREEN was developed for assessment of the groundwater pathway from leaching of radioactive and non radioactive substances from surface or buried sources. The code was designed for implementation in the Track I and Track II assessment of CERCLA (Comprehensive Environmental Response, Compensation and Liability Act) sites identified as low probability hazard at the Idaho National Engineering Laboratory (DOE, 1992). The code calculates the limiting soil concentration such that, after leaching and transport to the aquifer, regulatory contaminant levels in groundwater are not exceeded. The code uses a mass conservation approach to model three processes: contaminant release from a source volume, contaminant transport in the unsaturated zone, and contaminant transport in the saturated zone. The source model considers the sorptive properties and solubility of the contaminant. Transport in the unsaturated zone is described by a plug flow model. Transport in the saturated zone is calculated with a semi-analytical solution to the advection dispersion equation in groundwater. In Version 2.0, GWSCREEN has incorporated an additional source model to calculate the impacts to groundwater resulting from the release to percolation ponds. In addition, transport of radioactive progeny has also been incorporated. GWSCREEN has shown comparable results when compared against other codes using similar algorithms and techniques. This code was designed for assessment and screening of the groundwater pathway when field data is limited. It was not intended to be a predictive tool

  2. GWSCREEN: A semi-analytical model for assessment of the groundwater pathway from surface or buried contamination: Version 2.0 theory and user`s manual

    Energy Technology Data Exchange (ETDEWEB)

    Rood, A.S.

    1993-06-01

    GWSCREEN was developed for assessment of the groundwater pathway from leaching of radioactive and non radioactive substances from surface or buried sources. The code was designed for implementation in the Track I and Track II assessment of CERCLA (Comprehensive Environmental Response, Compensation and Liability Act) sites identified as low probability hazard at the Idaho National Engineering Laboratory (DOE, 1992). The code calculates the limiting soil concentration such that, after leaching and transport to the aquifer, regulatory contaminant levels in groundwater are not exceeded. The code uses a mass conservation approach to model three processes: contaminant release from a source volume, contaminant transport in the unsaturated zone, and contaminant transport in the saturated zone. The source model considers the sorptive properties and solubility of the contaminant. Transport in the unsaturated zone is described by a plug flow model. Transport in the saturated zone is calculated with a semi-analytical solution to the advection dispersion equation in groundwater. In Version 2.0, GWSCREEN has incorporated an additional source model to calculate the impacts to groundwater resulting from the release to percolation ponds. In addition, transport of radioactive progeny has also been incorporated. GWSCREEN has shown comparable results when compared against other codes using similar algorithms and techniques. This code was designed for assessment and screening of the groundwater pathway when field data is limited. It was not intended to be a predictive tool.

  3. Predictive geochemical modeling of uranium and other contaminants in laboratory columns in relatively oxidizing, carbonate-rich solutions

    International Nuclear Information System (INIS)

    Longmire, P.; Turney, W.R.; Mason, C.F.V.

    1994-01-01

    Carbonate heap leaching of uranium-contaminated soils and sediments represents a viable, cost-effective remediation technology. Column experiments have been conducted using 0.1, 0.25, and 0.5 M Na 2 CO 3 /NaHCO 3 solutions for leaching uranium from soils located adjacent to an incinerator at the Fernald Environmental Management Project (FEMP) site. Results from column experiments and geochemical modeling are used to quantitatively evaluate the effectiveness of heap leaching. Leach efficiencies of up to 72 wt.% of total uranium in CaO-agglomerated soil result from dissolution of uranium (U(VI)-dominated) minerals, formation of the soluble complex UO 2 (CO 3 ) 3 4- , and uranium desorption from clay minerals, ferric hydroxides, and humic acids. Parameters that control the extent of uranium extraction include pH, Eh, temperature, carbonate concentration, lixiviant-flow rate, pore-solution chemistry, solid phases, and soil texture

  4. The calculation of radiation fields of chemical contamination of nature with the use of a digital model

    International Nuclear Information System (INIS)

    Mehtiev, D.S.; Sultanov, D.A.; Azizov, B.M.

    2008-01-01

    Danger of contamination of the environment by convection of air and fluid transport in porous media arise while disposing of waste radioactive isotopes and chemical industry waste in underground deep-seated horizons. As a result there is eventually observed the formation of radioactive fields of local character. A lot of methods using for defining of radioactive fields of objects of the similar type, basically are based on the registration particles and quantum, emitted by nuclear of the corresponding elements in their radioactive decay. This is especially important for objects intended for placement in the mass of low permeable rocks, such as rock type. On the base of complex using of modern information basis created the model of induced radiation field of environment

  5. The effect of source herd and abattoir factors on pig carcass Salmonella contamination evaluated by multilevel modelling

    DEFF Research Database (Denmark)

    Baptista, Filipa Matos; Dahl, Jan; Nielsen, Liza Rosenbaum

    2010-01-01

    In Denmark, a Surveillance-and-Control Programme for Salmonella in pigs has been in place for several years. This study investigated factors associated with Salmonella pig carcass contamination, namely estimated daily number of Salmonella seropositive pigs delivered to slaughter, average Salmonella...... seroprevalence of the source herds that delivered each of five pigs contributing to the pool, weekday, year, season and abattoir size. A total of 20128 pooled carcass swabs collected in 22 Danish abattoirs, from 2002 to 2008, were included in a multilevel logistic regression model. Study results indicate...... that the probability of Salmonella positive carcasses is mainly influenced by the Salmonella herd seroprevalence of the swabbed pigs, the number of seropositive pigs delivered to the abattoir on the same day and weekday. Further reduction in carcass pool Salmonella prevalence may require new or improved methods...

  6. Validation of the VOLASOIL model using measurements from Dutch contaminated sites - Concentrations of four chlorinated compounds

    NARCIS (Netherlands)

    Wijnen HJ van; Lijzen JPA; LER

    2006-01-01

    The study reported here has shown the VOLASOIL model to be very useful for estimating the indoor air concentrations of the pollutants, tetrachloroethene and trichloroethene. The model is probably also useful for the degradation products, cis-dichloroethene and vinylchloride, but this was more

  7. Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives.

    Science.gov (United States)

    Voglar, Grega E; Leštan, Domen

    2011-08-30

    In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085mg kg(-1) of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12N mm(-2) achieved after S/S with CAC+PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC+Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Modeling Phytoremediation of Cadmium Contaminated Soil with Sunflower (Helianthus annus) Under Salinity Stress

    International Nuclear Information System (INIS)

    Motesharezadeh, B.; Navabzadeh, M.; Liyaghat, A. M.

    2016-01-01

    This study was carried out as a factorial experiment with 5 levels of cadmium (Cd) (o, 25, 50, 75, and 100 mg/kg), 5 levels of salinity (Control, 4, 5, 6, and 7 dS/m), and two soil textures (sandy loam and clay loam). The results showed that the amount of Cd in root and shoot of sunflower increased as soil salinity and Cd concentration increased. The best concentrations for Cd phytoremediation were 75 mg/kg in sandy loam and 100 mg/kg in clay loam. Mass-Hoffman model in simulating transpiration Cd stress as well as Homaee model in simulating salt stress indicated the best results in light soils. By multiplying the salinity stress model by Cd stress model, the simultaneous model for each soil was calculated. These models in light soil (r2=0.68) and heavy soil (r2=0.81) were compatible with measured values. In the heavy soil, absorbed Cd by plant along with increased salinity reflected low changes, but changes in Cd absorbed by plants in the heavy soil were more uniform than in the light soil. In conclusion, for estimating the Cd uptake, the model had a better performance in the heavy soil (under salt stress).

  9. Modeling contaminant transport in porous media in relation to nuclear-waste disposal: a review

    International Nuclear Information System (INIS)

    Grove, D.B.; Kipp, K.L.

    1980-01-01

    The modeling of solute transport in saturated porous media is reviewed as it is applied to the movement of radioactive waste in the subsurface. Those processes, both physical and chemical, that affect radionuclide movement are discussed and the references that best illustrate these processes listed. Movement is separated into convection, convection-dispersion, and convection-dispersion and chemical reactions. Solutions of equations describing such movement are divided into one-, two-, and three-dimensional analytical and numerical examples. Discussions of recent work in the area of stochastic modeling are followed by discussions of applications of the models to selected field sites

  10. Supporting models for the evaluation of environmental effects after a radioactive contamination

    International Nuclear Information System (INIS)

    Martin Garcia, J.E.; Gallego Diaz, E.

    1993-01-01

    Within the project on optimization of site recovery measures after nuclear accidents which is being sponsored by the Commission of European Communities (CEC), two different models have been developed: URBAPAT and AGROPAT. Both models are a more realistic approach to deposited radionuclides performance and resultant doses either via external exposure at urban areas and via food products from rural areas, than other current codes on analysis of effects. Those models could support the adoption of protection measures in the aftermath of a radioactive accident, (by using, for instance, cost/profit analysis techniques or multiatribute tools), in order to improve the existing situation and to obtain the best solution for individuals and society. Developed models are flexible enough to be adapted to different sites and include the possibility to make sensitivity and uncertainty analysis of all parameters, as well as to consider a wide variety of protection measures

  11. A methodology for determining optimal durations for the use of contaminated crops as fodder following a nuclear accident using a dynamic food-chain model

    International Nuclear Information System (INIS)

    Hwang, Won Tae; Han, Moon Hee; Cho, Gyuseong

    2000-01-01

    A methodology for determining optimal durations for the use of contaminated crops as fodder was designed based on cost-benefit analysis. Illustrative results of the application of this methodology to pigs are presented for the hypothetical deposition of radionuclides on August 15 when a number of crops are fully developed in Korean agricultural conditions. For investigating the appropriateness of the use of contaminated crops as fodder, the net benefit from this action was compared with the imposition of a ban on human consumption of contaminated crops without alternative use. The time-dependent radionuclide concentrations in crops and pork after the deposition event were predicted from a dynamic food-chain model DYNACON. The net benefit from the actions was quantitatively evaluated in terms of cost equivalent of the doses incurred or averted and the monetary costs needed to implement the action. The optimal duration for the use of contaminated crops as fodder depended on a number of factors such as radionuclide, variety of crops fed as fodder and duration of the action. Such action was more cost effective for 137 Cs deposition than for 90 Sr or 131 I deposition. The use of contaminated crops as fodder can be an effective response to a public reluctance to consume contaminated crops

  12. Tests of the validity of a model relating frequency of contaminated items and increasing radiation dose

    International Nuclear Information System (INIS)

    Tallentire, A.; Khan, A.A.

    1975-01-01

    The 60 Co radiation response of Bacillus pumilus E601 spores has been characterized when present in a laboratory test system. The suitability of test vessels to act as both containers for irradiation and culture vessels in sterility testing has been checked. Tests have been done with these spores to verify assumptions basic to the general model described in a previous paper. First measurements indicate that the model holds with this laboratory test system. (author)

  13. Mass balance modelling of contaminants in river basins: a flexible matrix approach.

    Science.gov (United States)

    Warren, Christopher; Mackay, Don; Whelan, Mick; Fox, Kay

    2005-12-01

    A novel and flexible approach is described for simulating the behaviour of chemicals in river basins. A number (n) of river reaches are defined and their connectivity is described by entries in an n x n matrix. Changes in segmentation can be readily accommodated by altering the matrix entries, without the need for model revision. Two models are described. The simpler QMX-R model only considers advection and an overall loss due to the combined processes of volatilization, net transfer to sediment and degradation. The rate constant for the overall loss is derived from fugacity calculations for a single segment system. The more rigorous QMX-F model performs fugacity calculations for each segment and explicitly includes the processes of advection, evaporation, water-sediment exchange and degradation in both water and sediment. In this way chemical exposure in all compartments (including equilibrium concentrations in biota) can be estimated. Both models are designed to serve as intermediate-complexity exposure assessment tools for river basins with relatively low data requirements. By considering the spatially explicit nature of emission sources and the changes in concentration which occur with transport in the channel system, the approach offers significant advantages over simple one-segment simulations while being more readily applicable than more sophisticated, highly segmented, GIS-based models.

  14. Light contamination

    International Nuclear Information System (INIS)

    Cepeda Pena, William Enrique

    1998-01-01

    The article tries on the wrong use of the artificial light, of the main problems of the light contamination, dispersion of the light, noxious effects of the light contamination, ecological effects, effects on the man's biological rhythm, economic effects and effects about the civic and vial security, among other topics

  15. Evaluation and Quantification of Uncertainty in the Modeling of Contaminant Transport and Exposure Assessment at a Radioactive Waste Disposal Site

    Science.gov (United States)

    Tauxe, J.; Black, P.; Carilli, J.; Catlett, K.; Crowe, B.; Hooten, M.; Rawlinson, S.; Schuh, A.; Stockton, T.; Yucel, V.

    2002-12-01

    The disposal of low-level radioactive waste (LLW) in the United States (U.S.) is a highly regulated undertaking. The U.S. Department of Energy (DOE), itself a large generator of such wastes, requires a substantial amount of analysis and assessment before permitting disposal of LLW at its facilities. One of the requirements that must be met in assessing the performance of a disposal site and technology is that a Performance Assessment (PA) demonstrate "reasonable expectation" that certain performance objectives, such as dose to a hypothetical future receptor, not be exceeded. The phrase "reasonable expectation" implies recognition of uncertainty in the assessment process. In order for this uncertainty to be quantified and communicated to decision makers, the PA computer model must accept probabilistic (uncertain) input (parameter values) and produce results which reflect that uncertainty as it is propagated through the model calculations. The GoldSim modeling software was selected for the task due to its unique facility with both probabilistic analysis and radioactive contaminant transport. Probabilistic model parameters range from water content and other physical properties of alluvium to the activity of radionuclides disposed to the amount of time a future resident might be expected to spend tending a garden. Although these parameters govern processes which are defined in isolation as rather simple differential equations, the complex interaction of couple processes makes for a highly nonlinear system with often unanticipated results. The decision maker has the difficult job of evaluating the uncertainty of modeling results in the context of granting permission for LLW disposal. This job also involves the evaluation of alternatives, such as the selection of disposal technologies. Various scenarios can be evaluated in the model, so that the effects of, for example, using a thicker soil cap over the waste cell can be assessed. This ability to evaluate mitigation

  16. Geoinformational modelling of the land use of Polesye and Opolje landscapes in Bryansk region (Russia) under conditions of 137Cs radionuclides contamination

    Science.gov (United States)

    Nenko, Christina; Linnik, Vitaliy; Volkova, Nadezhda

    2015-04-01

    Significant part of Russian Federation was contaminated by 137Cs radionuclides due to Chernobyl disaster in 1986. South-western part of Bryansk region has suffered the most. Study area (the central part of Bryansk region, Polesye and high plains landscapes) is situated outside the officially specified zone of contamination with contamination levels under 1 Ci / km2. Nevertheless, such contamination levels (which are 20 times greater than levels of global fallout) require particular attention as it may contain a threat of the land use and the health of population, living within the territory. Radioactive contamination within the model area was formed as a result of a "dry" deposition from the atmosphere. Consequently, the initial contamination of soil by isotopes 137Cs, unlike the western part of the Bryansk region, was spread relatively equally. The main part of 137Cs (up to 90%) in natural landscapes is contained in the top 5 cm of soil, which itself creates danger of biogeochemical migration from soil to plants. In agricultural landscapes under cultivation 137Cs is uniformly spread within a 20 cm layer of soil and can also come from soil to plants grown in the fields. The area of radioactive contamination that was formed during the period of deposition (late April - early May 1986), is exposed to the processes of secondary redistribution. It is influenced by several factors as topography, vegetation type, proportion of arable soils, soil humidity, soil texture etc. In the presented study there was evaluated the impact of these factors on the secondary redistribution of 137Cs. Sustainable development of agricultural production in the contaminated territories requires managing a number of measures to reduce radiation risks to the population. Regarding this point the greatest threat may be represented by milk production, as well as picking berries and mushrooms. Planning of the sustainable use of the territory requires an evaluation of contamination levels within

  17. Phytoremediation modelling - phytoextraction of 137Cs, 133Ba, and 90Sr from liquid media and artificially contaminated soil

    International Nuclear Information System (INIS)

    Smrcek, S.; Masnerova, G.

    2002-01-01

    The phytoremediation model based on experiments with plants cultivated in vitro in media supplemented with radionuclide salts was investigated. The plant species Brassica napus, Sinapis alba, Helianthus annuus, Zea mays and Pisum sativum were cultivated on the Murashige-Skoog basal salt mixture enriched with salts of 137 Cs, 133 Ba, and 90 Sr in aseptic conditions. The time-dependent radioactivity decrease in the medium was determined using LSC, and the phytoextraction curves were plotted. Radioactivity in the plant roots and shoots was measured and the efficiency of phytoextraction and the distribution between the roots and shoots as a measure of radionuclide transport in the plant tissues were calculated for each of the plants used. Cultivation experiments were also performed on artificially contaminated soil. Seeds of the plants were placed into contaminated soil and cultivated for 2 months in conditions similar to those of the in vitro experiments. The extracted radioactivity and distribution between roots and shoots were determined. The in vitro experiments simulated extraction of the radionuclide salt from solution analogously to real extraction from the soil solution, while the processes occurring in the rhizosphere were eliminated. The phytoextraction efficiency in terms of the percentage of the starting radioactivity ranged from 12 to 31 % for 90 Sr, 8 to 24% for 137 Cs, and 12 to 17 % for 133 Ba in a cultivation cycle. The root/shoot radioactivity ratios demonstrate that the plant species used may be suitable for real phytoremediation. The experiments in which the plants were cultivated from seeds in artificial contaminated substrate showed that the ability of roots to extract radionuclide salts from their environment remains unchanged. The relative efficiency values were lower than for the extraction from solutions (3 to 11.5 % for 90 Sr, 1.5 to 4 % for 137 Cs, and 1 to 6.2 %, for 133 Ba), but in this process, the equilibrium between the soil particles

  18. Hanford Tanks 241-C-202 and 241-C-203 Residual Waste Contaminant Release Models and Supporting Data

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Mattigod, Shas V.; Schaef, Herbert T.; Arey, Bruce W.

    2007-09-13

    As directed by Congress, the U. S. Department of Energy (DOE) established the Office of River Protection in 1998 to manage DOE's largest, most complex environmental cleanup project – retrieval of radioactive waste from Hanford tanks for treatment and eventual disposal. Sixty percent by volume of the nation's high-level radioactive waste is stored at Hanford in aging deteriorating tanks. If not cleaned up, this waste is a threat to the Columbia River and the Pacific Northwest. CH2M Hill Hanford Group, Inc., is the Office of River Protection's prime contractor responsible for the storage, retrieval, and disposal of Hanford's tank waste. As part of this effort, CH2M HILL Hanford Group, Inc. contracted with Pacific Northwest National Laboratory (PNNL) to develop release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for DOE.

  19. Estimates of potential childhood lead exposure from contaminated soil using the US EPA IEUBK Model in Sydney, Australia.

    Science.gov (United States)

    Laidlaw, Mark A S; Mohmmad, Shaike M; Gulson, Brian L; Taylor, Mark P; Kristensen, Louise J; Birch, Gavin

    2017-07-01

    Surface soils in portions of the Sydney (New South Wales, Australia) urban area are contaminated with lead (Pb) primarily from past use of Pb in gasoline, the deterioration of exterior lead-based paints, and industrial activities. Surface soil samples (n=341) were collected from a depth of 0-2.5cm at a density of approximately one sample per square kilometre within the Sydney estuary catchment and analysed for lead. The bioaccessibility of soil Pb was analysed in 18 samples. The blood lead level (BLL) of a hypothetical 24 month old child was predicted at soil sampling sites in residential and open land use using the United States Environmental Protection Agency (US EPA) Integrated Exposure Uptake and Biokinetic (IEUBK) model. Other environmental exposures used the Australian National Environmental Protection Measure (NEPM) default values. The IEUBK model predicted a geometric mean BLL of 2.0±2.1µg/dL using measured soil lead bioavailability measurements (bioavailability =34%) and 2.4±2.8µg/dL using the Australian NEPM default assumption (bioavailability =50%). Assuming children were present and residing at the sampling locations, the IEUBK model incorporating soil Pb bioavailability predicted that 5.6% of the children at the sampling locations could potentially have BLLs exceeding 5µg/dL and 2.1% potentially could have BLLs exceeding 10µg/dL. These estimations are consistent with BLLs previously measured in children in Sydney. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Use of fugacity model to analyze temperature-dependent removal of micro-contaminants in sewage treatment plants.

    Science.gov (United States)

    Thompson, Kelly; Zhang, Jianying; Zhang, Chunlong

    2011-08-01

    Effluents from sewage treatment plants (STPs) are known to contain residual micro-contaminants including endocrine disrupting chemicals (EDCs) despite the utilization of various removal processes. Temperature alters the efficacy of removal processes; however, experimental measurements of EDC removal at various temperatures are limited. Extrapolation of EDC behavior over a wide temperature range is possible using available physicochemical property data followed by the correction of temperature dependency. A level II fugacity-based STP model was employed by inputting parameters obtained from the literature and estimated by the US EPA's Estimations Programs Interface (EPI) including EPI's BIOWIN for temperature-dependent biodegradation half-lives. EDC removals in a three-stage activated sludge system were modeled under various temperatures and hydraulic retention times (HRTs) for representative compounds of various properties. Sensitivity analysis indicates that temperature plays a significant role in the model outcomes. Increasing temperature considerably enhances the removal of β-estradiol, ethinyestradiol, bisphenol, phenol, and tetrachloroethylene, but not testosterone with the highest biodegradation rate. The shortcomings of BIOWIN were mitigated by the correction of highly temperature-dependent biodegradation rates using the Arrhenius equation. The model predicts well the effects of operating temperature and HRTs on the removal via volatilization, adsorption, and biodegradation. The model also reveals that an impractically long HRT is needed to achieve a high EDC removal. The STP model along with temperature corrections is able to provide some useful insight into the different patterns of STP performance, and useful operational considerations relevant to EDC removal at winter low temperatures. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Reconstruction of the external dose of evacuees from the contaminated areas based on simulation modelling

    International Nuclear Information System (INIS)

    Meckbach, R.; Chumak, V.V.

    1996-01-01

    Model calculations are being performed for the reconstruction of individual external gamma doses of population evacuated during the Chernobyl accident from the city of Pripyat and other settlements of the 30-km zone. The models are based on sets of dose rate measurements performed during the accident, on individual behavior histories of more than 30000 evacuees obtained by questionnaire survey and on location factors determined for characteristic housing buildings. Location factors were calculated by Monte Carlo simulations of photon transport for a typical housing block and village houses. Stochastic models for individual external dose reconstruction are described. Using Monte Carlo methods, frequency distributions representing the uncertainty of doses are calculated from an assessment of the uncertainty of the data. The determination of dose rate distributions in Pripyat is discussed. Exemplary results for individual external doses are presented

  2. Modeling diffuse sources of surface water contamination with plant protection products

    Science.gov (United States)

    Wendland, Sandra; Bock, Michael; Böhner, Jürgen; Lembrich, David

    2015-04-01

    Entries of chemical pollutants in surface waters are a serious environmental problem. Among water pollutants plant protection products (ppp) from farming practice are of major concern not only for water suppliers and environmental agencies, but also for farmers and industrial manufacturers. Lost chemicals no longer fulfill their original purpose on the field, but lead to severe damage of the environment and surface waters. Besides point-source inputs of chemical pollutants, the diffuse-source inputs from agricultural procedures play an important and not yet sufficiently studied role concerning water quality. The two most important factors for diffuse inputs are erosion and runoff. The latter usually occurs before erosion begins, and is thus often not visible in hindsight. Only if it has come to erosion, it is obvious to expect runoff in foresight at this area, too. In addition to numerous erosion models, there are also few applications to model runoff processes available. However, these conventional models utilize approximations of catchment parameters based on long-term average values or theoretically calculated concentration peaks which can only provide indications to relative amounts. Our study aims to develop and validate a simplified spatially-explicit dynamic model with high spatiotemporal resolution that enables to measure current and forecast runoff potential not only at catchment scale but field-differentiated. This method allows very precise estimations of runoff risks and supports risk reduction measures to be targeted before fields are treated. By focusing on water pathways occurring on arable land, targeted risk reduction measures like buffer strips at certain points and adapted ppp use can be taken early and pollution of rivers and other surface waters through transported pesticides, fertilizers and their products could be nearly avoided or largely minimized. Using a SAGA-based physical-parametric modeling approach, major factors influencing runoff

  3. Modelling characteristics to predict Legionella contamination risk - Surveillance of drinking water plumbing systems and identification of risk areas.

    Science.gov (United States)

    Völker, Sebastian; Schreiber, Christiane; Kistemann, Thomas

    2016-01-01

    For the surveillance of drinking water plumbing systems (DWPS) and the identification of risk factors, there is a need for an early estimation of the risk of Legionella contamination within a building, using efficient and assessable parameters to estimate hazards and to prioritize risks. The precision, accuracy and effectiveness of ways of estimating the risk of higher Legionella numbers (temperature, stagnation, pipe materials, etc.) have only rarely been empirically assessed in practice, although there is a broad consensus about the impact of these risk factors. We collected n = 807 drinking water samples from 9 buildings which had had Legionella spp. occurrences of >100 CFU/100mL within the last 12 months, and tested for Legionella spp., L. pneumophila, HPC 20°C and 36°C (culture-based). Each building was sampled for 6 months under standard operating conditions in the DWPS. We discovered high variability (up to 4 log(10) steps) in the presence of Legionella spp. (CFU/100 mL) within all buildings over a half year period as well as over the course of a day. Occurrences were significantly correlated with temperature, pipe length measures, and stagnation. Logistic regression modelling revealed three parameters (temperature after flushing until no significant changes in temperatures can be obtained, stagnation (low withdrawal, qualitatively assessed), pipe length proportion) to be the best predictors of Legionella contamination (>100 CFU/100 mL) at single outlets (precision = 66.7%; accuracy = 72.1%; F(0.5) score = 0.59). Copyright © 2015 Elsevier GmbH. All rights reserved.

  4. Geological characterization and solute transport model investigations of contaminated sites in urban areas (Denmark)

    DEFF Research Database (Denmark)

    Andersen, Theis Raaschou; Poulsen, Søren Erbs; Thomsen, Peter

    the two field sites includes only lithological profiles from boreholes. In order to increase the density of the field data, the two areas were mapped with Electrical Resistivity Tomography (ERT). Based on the borehole information and the high-density geophysical data, detailed 3D geological models...

  5. Modeled Watershed Runoff Associated with Variations in Precipitation Data, with Implications for Contaminant Fluxes: Initial Results

    Science.gov (United States)

    Precipitation is one of the primary forcing functions of hydrologic and watershed fate and transport models; however, in light of advances in precipitation estimates across watersheds, data remain highly uncertain. A wide variety of simulated and observed precipitation data are a...

  6. Modeling of Contaminant Migration through Porous Media after Underground Coal Gasification in Shallow Coal Seam

    Czech Academy of Sciences Publication Activity Database

    Soukup, Karel; Hejtmánek, Vladimír; Čapek, P.; Stanczyk, K.; Šolcová, Olga

    2015-01-01

    Roč. 140, DEC (2015), s. 188-197 ISSN 0378-3820 Grant - others:RFCS(XE) RFCR-CT-2011-00002 Institutional support: RVO:67985858 Keywords : underground coal gasification * transport phenomena modeling * transport parameters Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.847, year: 2015

  7. Development of a resuspension model for contaminated soils. Application to the Palomares area; Desarrollo de un modelo de resuspension de suelos contaminados. Aplicacion al area de Palomares

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Olivares, A

    1993-07-01

    A model is presented which has been used to simulate the wind resuspension and transport of contaminated soil in the area surrounding the Palomares village, in Southern Spain. The model uses site specific data and some generic parameters as resuspension rate and deposition velocity. The model is able to predict the order of magnitude of the observed air concentration of activity. Some lines of research are suggested which could improve the understanding of the phenomena involved. (Author) 20 refs.

  8. A hybrid machine learning model to estimate nitrate contamination of production zone groundwater in the Central Valley, California

    Science.gov (United States)

    Ransom, K.; Nolan, B. T.; Faunt, C. C.; Bell, A.; Gronberg, J.; Traum, J.; Wheeler, D. C.; Rosecrans, C.; Belitz, K.; Eberts, S.; Harter, T.

    2016-12-01

    A hybrid, non-linear, machine learning statistical model was developed within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500 m below ground surface in the Central Valley, California. A database of 213 predictor variables representing well characteristics, historical and current field and county scale nitrogen mass balance, historical and current landuse, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6,000 private supply and public supply wells measured previously for nitrate and located throughout the study area. The machine learning method, gradient boosting machine (GBM) was used to screen predictor variables and rank them in order of importance in relation to the groundwater nitrate measurements. The top five most important predictor variables included oxidation/reduction characteristics, historical field scale nitrogen mass balance, climate, and depth to 60 year old water. Twenty-two variables were selected for the final model and final model errors for log-transformed hold-out data were R squared of 0.45 and root mean square error (RMSE) of 1.124. Modeled mean groundwater age was tested separately for error improvement in the model and when included decreased model RMSE by 0.5% compared to the same model without age and by 0.20% compared to the model with all 213 variables. 1D and 2D partial plots were examined to determine how variables behave individually and interact in the model. Some variables behaved as expected: log nitrate decreased with increasing probability of anoxic conditions and depth to 60 year old water, generally decreased with increasing natural landuse surrounding wells and increasing mean groundwater age, generally increased with increased minimum depth to high water table and with increased base flow index value. Other variables exhibited much more erratic or noisy behavior in

  9. A three-dimensional multiphase flow model for assesing NAPL contamination in porous and fractured media, 1. Formulation

    Science.gov (United States)

    Huyakorn, P. S.; Panday, S.; Wu, Y. S.

    1994-06-01

    A three-dimensional, three-phase numerical model is presented for stimulating the movement on non-aqueous-phase liquids (NAPL's) through porous and fractured media. The model is designed for practical application to a wide variety of contamination and remediation scenarios involving light or dense NAPL's in heterogeneous subsurface systems. The model formulation is first derived for three-phase flow of water, NAPL and air (or vapor) in porous media. The formulation is then extended to handle fractured systems using the dual-porosity and discrete-fracture modeling approaches The model accommodates a wide variety of boundary conditions, including withdrawal and injection well conditions which are treated rigorously using fully implicit schemes. The three-phase of formulation collapses to its simpler forms when air-phase dynamics are neglected, capillary effects are neglected, or two-phase-air-liquid, liquid-liquid systems with one or two active phases are considered. A Galerkin procedure with upstream weighting of fluid mobilities, storage matrix lumping, and fully implicit treatment of nonlinear coefficients and well conditions is used. A variety of nodal connectivity schemes leading to finite-difference, finite-element and hybrid spatial approximations in three dimensions are incorporated in the formulation. Selection of primary variables and evaluation of the terms of the Jacobian matrix for the Newton-Raphson linearized equations is discussed. The various nodal lattice options, and their significance to the computational time and memory requirements with regards to the block-Orthomin solution scheme are noted. Aggressive time-stepping schemes and under-relaxation formulas implemented in the code further alleviate the computational burden.

  10. S/O modeling technique for optimal containment of light hydrocarbons in contaminated unconfined aquifers

    International Nuclear Information System (INIS)

    Cooper, G.S. Jr.; Kaluarachchi, J.J.; Peralta, R.C.

    1993-01-01

    An innovative approach is presented to minimize pumping for immobilizing a floating plume of a light non-aqueous phase liquid (LNAPL). The best pumping strategy is determined to contain the free oil product and provide for gradient control of the water table. This approach combined detailed simulation, statistical analysis, and optimization. This modeling technique uses regression equations that describe system response to variable pumping stimuli. The regression equations were developed from analysis of systematically performed simulations of multiphase flow in an areal region of an unconfined aquifer. Simulations were performed using ARMOS, a finite element model. ARMOS can be used to simulate a spill, leakage from subsurface storage facilities and recovery of hydrocarbons from trenches or pumping wells to design remediation schemes

  11. The research of contamination regularities of historical buildings and architectural monuments by methods of computer modeling

    Directory of Open Access Journals (Sweden)

    Kuzmichev Andrey A.

    2017-01-01

    Full Text Available Due to the active step of urbanization and rapid development of industry the external appearance of buildings and architectural monuments of urban environment from visual ecology position requires special attention. Dust deposition by polluted atmospheric air is one of the key aspects of degradation of the facades of buildings. With the help of modern computer modeling methods it is possible to evaluate the impact of polluted atmospheric air on the external facades of the buildings in order to save them.

  12. Aquatic Contaminant and Mercury Simulation Modules Developed for Hydrologic and Hydraulic Models

    Science.gov (United States)

    2016-07-01

    Technical Director, and William Jones was Program Manager . The report was prepared by Dr. Zhonglong Zhang of LimnoTech, under contract to the U.S. Army...Corps of Engineers ERDC/EL TR-16-8 xi WARMF Watershed Analysis Risk Management Framework WASP Water Quality Analysis Simulation Program ERDC/EL...water qaulity become indispensable tools used by environ- mental analysts. Over the last three decades, a variety of H&H models have been developed for

  13. Development of Operation Management Model of Groundwater According to Nitrate Contamination

    Directory of Open Access Journals (Sweden)

    Elahe Pourfarahabadi

    2014-10-01

    Full Text Available Nitrate is one of the most important groundwater pollutants with such different sources as chemical fertilizers, pesticides, or domestic and industrial wastewater. In this research, the optimal operation of groundwater wells in aquifers with nitrate pollution is investigated using simulation and optimization techniques. For the simulation part, an artificial neural network (ANN model is developed, and for the optimization model, the particle swarm optimization (PSO is used. Considering the high nitrate concentration in Karaj area and its increase in recent years, the northern part of this aquifer is selected as a case study to apply the proposed methodology. A seasonal ANN model is developed with input layers including well discharge in the current and previous seasons, nitrate concentration in the previous season, aquifer thickness, and well coordinates, all selected based on sensitivity analysis. The results of PSO algorithm shows that nitrate concentration can be controlled by increasing or decreasing well discharge in different zones. Therefore, it is possible to reduce nitrate concentration in critical areas by changing the spatial distribution of groundwater extractions in different zones keeping the total discharge constant.

  14. Application of the differential neural network observer to the kinetic parameters identification of the anthracene degradation in contaminated model soil

    Energy Technology Data Exchange (ETDEWEB)

    Poznyak, Tatyana [Superior School of Chemical Engineering, National Polytechnic Institute of Mexico (ESIQIE-IPN), Edif. 7, UPALM, C.P. 07738, Mexico D.F. (Mexico)]. E-mail: tpoznyak@ipn.mx; Garcia, Alejandro [Department of Automatic Control, CINVESTAV-IPN, Av. Instituto Politecnico Nacional, Col. San Pedro Zacatenco, C.P. 07360, Mexico D.F. (Mexico); Chairez, Isaac [Department of Automatic Control, CINVESTAV-IPN, Av. Instituto Politecnico Nacional, Col. San Pedro Zacatenco, C.P. 07360, Mexico D.F. (Mexico); Gomez, Miriam [Superior School of Chemical Engineering, National Polytechnic Institute of Mexico (ESIQIE-IPN), Edif. 7, UPALM, C.P. 07738, Mexico D.F. (Mexico); Poznyak, Alexander [Department of Automatic Control, CINVESTAV-IPN, Av. Instituto Politecnico Nacional, Col. San Pedro Zacatenco, C.P. 07360, Mexico D.F. (Mexico)]. E-mail: apoznyak@ctrl.cinvestav.mx

    2007-07-31

    In this work a new technique dealing with differential neural network observer (DNNO), which is related with differential neural networks (DNN) approach, is applied to estimate the anthracene dynamics decomposition and to identify the kinetic parameters in a contaminated model soil treatment by simple ozonation. To obtain the experimental data set, the model soil (sand) is combined with an initial anthracene concentration of 3.24 mg/g and treated by ozone (with the ozone initial concentration 16 mg/L) during 90 min in a reactor by the 'fluid bed' principle. The anthracene degradation degree was controlled by UV-vis spectrophotometry and HPLC techniques. Based on the HPLC data, the obtained results confirm that anthracene may be decomposed completely in the solid phase by simple ozonation during 20 min and by-products of ozonation are started to be destroyed after 30 min of treatment. In the ozonation process the ozone concentration in the gas phase at the reactor outlet is registered by an ozone detector. The variation of this parameter is used to obtain the summary characteristic curve of the anthracene ozonation (ozonogram). Then, using the experimental decomposition dynamics of anthracene and the ozonogram, the proposed DNNO is trained to reconstruct the anthracene decomposition and to estimate the anthracene ozonation constant using the DNN technique and a modified Least Square method.

  15. Application of the differential neural network observer to the kinetic parameters identification of the anthracene degradation in contaminated model soil

    International Nuclear Information System (INIS)

    Poznyak, Tatyana; Garcia, Alejandro; Chairez, Isaac; Gomez, Miriam; Poznyak, Alexander

    2007-01-01

    In this work a new technique dealing with differential neural network observer (DNNO), which is related with differential neural networks (DNN) approach, is applied to estimate the anthracene dynamics decomposition and to identify the kinetic parameters in a contaminated model soil t