Change in Soil Porosity under Load

Science.gov (United States)

Dyba, V. P.; Skibin, E. G.

2017-11-01

The theoretical basis for the process of soil compaction under various loading paths is considered in the article, the theoretical assumptions are compared with the results of the tests of clay soil on a stabilometer. The variant of the critical state model of the sealing plastic-rigid environment is also considered the strength characteristics of which depend on the porosity coefficient. The loading surface is determined by the results of compression and stabilometrical tests. In order to clarify the results of this task, it is necessary to carry out stabilometric tests under conditions of simple loading, i.e. where the vertical pressure would be proportional to the compression pressure σ3 = kσ1. Within the study the attempts were made to confirm the model given in the beginning of the article by laboratory tests. After the analysis of the results, the provided theoretical assumptions were confirmed.

A new elasto-plastic spring element for cyclic loading of piles using the p-y curve concept

DEFF Research Database (Denmark)

Hededal, Ole; Klinkvort, Rasmus Tofte

2010-01-01

Modeling the response of large diameter piles subjected to lateral loading is most often done by means of p-y-curves in combination withWinkler beam models. Traditionally the p-y curves are formulated as non-linear (elastic) relations between the lateral movement y and the soil response pressure p....... The present model can account for effects like pre-consolidation and creation of gaps between pile and soil at reversed loading. Results indicate that the model is able to capture hysteresis during loading with full cycles and model the accumulated displacement observed on piles subjected to “half cycles......” as e.g. seen from centrifuge tests carried out. This article presents the theoretical formulations, discusses numerical implementation and finally presents simulations....

Studies on P availability of volcanic ash soils from Chile amended with various P fertilizers

International Nuclear Information System (INIS)

Pino, I.; Parada, A.M.; Luzio, W.

2002-01-01

A high P retention capacity and a low P availability to plants characterize the volcanic ash soils from Chile. For this reason, the purpose of this incubation study was to compare different extraction methods, P sorption, and estimations of the agronomic efficiencies of different fertilizers in these soils. In order to study the agronomic effectiveness of rock phosphates and their suitability for direct application, 32 P was used for assessing the bioavailability of P and the efficiency in rock phosphate materials. Incubation experiments were carried out to measure the soil parameters of Intensity, Quantity and Capacity. Triple superphosphate (TSP, 20% P) was applied to the soil in granular form, whereas local Bahia Inglesa PR (7.68% P) was added as powder. These Chilean soils have a very high P fixing capacity with maximum P adsorption values greater than 1000 mg P/kg soil. Moreover these soils also exhibit higher fixation strength compared to the Venezuelan soils. In relation to isotopic exchangeable P, (E value), the Chilean soils have a low value of isotopic exchangeable P without added P. There is a progressive increase in E value, under increasing P fertilizer rates, particularly at 500 ppm P and above. The P application as PR or TSP did not reduce the P retention capacity of the Perquenco soil. Nevertheless, it exists a positive effect when the P sources are applied as mixtures, which induces a decrease in the P retention percentage. Available P in this soil increased from 3.6 ppm P for the check to a maximum of 20 ppm P for the highest TSP rates, reaching medium to high values according to the extraction methodology used. (author)

Phosphorus-loaded biochar changes soil heavy metals availability and uptake potential of maize (Zea mays L.) plants.

Science.gov (United States)

Ahmad, Munir; Usman, Adel R A; Al-Faraj, Abdullah S; Ahmad, Mahtab; Sallam, Abdelazeem; Al-Wabel, Mohammad I

2018-03-01

Biochar (BC) was produced by pyrolyzing the date palm leaf waste at 600 °C and then loaded with phosphorus (P) via sorption process. Greenhouse pot experiment was conducted to investigate the application effects of BC and P-loaded biochar (BCP) on growth and availability of P and heavy metals to maize (Zea mays L.) plants grown in contaminated mining soil. The treatments consisted of BC and BCP (at application rates of 5, 10, 20, and 30 g kg -1 of soil), recommended NK and NPK, and a control (no amendment). Sorption experiment showed that Langmuir predicted maximum P sorption capacity of BC was 13.71 mg g -1 . Applying BCP increased the soil available P, while BC and BCP significantly decreased the soil labile heavy metals compared to control. Likewise, heavy metals in exchangeable and reducible fractions were transformed to more stable fraction with BC and BCP applications. The highest application rate of BCP (3%) was most effective treatment in enhancing plant growth parameters (shoot and root lengths and dry matter) and uptake of P and heavy metals by 2-3 folds. However, based on metal uptake and phytoextraction indices, total heavy metals extraction by maize plants was very small for practical application. It could be concluded that using P-loaded biochar as a soil additive may be considered a promising tool to immobilize heavy metals in contaminated mining areas, while positive effects on the biomass growth of plants may assist the stabilization of contaminated areas affected by wind and water erosion. Copyright © 2017 Elsevier Ltd. All rights reserved.

EFFECT OF DIFFERENT LEVELS AGROECOLOGICAL LOADS ON BIOCHEMICAL CHARACTERISTICS OF SOIL

OpenAIRE

A. V. Shchur; D. V. Vinogradov; V. P. Valckho

2016-01-01

Aim. To study the effect of different levels of agri-environmental loads on the enzymatic activity of the soil.Methods. Isolation of soil fauna was conducted by thermogradient. Ecological characteristics of soil biota community was determined by ecological indices. The enzymatic activity of soil under different crops and at different levels of agri-environmental loads in our experiments was determined by methods proven in the laboratory soil enzymology Institute of Experimental Botany name V....

Swelling Behaviour of Superabsorbent Polymers for Soil Amendment under Different Loads

Directory of Open Access Journals (Sweden)

Krzysztof Lejcuś

2018-03-01

Full Text Available One of the most important among the numerous applications of superabsorbent polymers (SAPs, also known as hydrogels, is soil improvement and supporting plant vegetation in agriculture and environmental engineering. Currently, when water scarcity involves water stress, they are becoming still more commonly used for water retention in soil. As it turns out, one of the major factors influencing the superabsorbent polymers water retention capacity (WRC is the load of soil. The study presents test results of absorbency under load (AUL of SAPs. The object of the analysis was cross-linked copolymer of acrylamide and potassium acrylate, of a granulation of 0.50–3.15 mm. The authors analysed the water absorption capacity of the superabsorbent polymers under loads characteristic for 3 different densities of soil (1.3 g∙cm−3, 0.9 g∙cm−3, 0.5 g∙cm−3 and three different depths of application (10 cm, 20 cm, and 30 cm. Soil load and bulk densities were simulated by using weights. The experiments were conducted with a Mecmesin Multitest 2.5-xt apparatus. The obtained results demonstrate a very significant reduction in water absorption capacity by SAP under load. For a 30 cm deep layer of soil of bulk density of 1.3 g∙cm−3, after 1 h, this value amounted to 5.0 g∙g−1, and for the control sample without load, this value amounted to more than 200 g∙g−1. For the lowest load in the experiment, which was 0.49 kPa (10 cm deep layer of soil of a bulk density of 0.5 g∙cm−3, this value was 33.0 g∙g−1 after 60 min. Loads do not only limit the volume of the swelling superabsorbent polymer but they also prolong the swelling time. The soil load caused a decrease in the absorption capacity from 338.5 g∙g−1 to 19.3 g∙g−1, as well as a prolongation of the swelling time. The rate parameter (time required to reach 63% of maximum absorption capacity increased from 63 min for the control sample to more than 300 min for the largest analysed

Soil Plasticity Model for Analysis of Collapse Load on Layers Soil

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Md Nujid Masyitah

2016-01-01

Full Text Available Natural soil consist of soil deposits which is a soil layer overlying a thick stratum of another soil. The bearing capacity of layered soil studies have been conducted using different approach whether theoretical, experimental and combination of both. Numerical method in computer programme has become a powerful tool in solving complex geotechnical problems. Thus in numerical modelling, stress-strain soil behaviour is well predicted, design and interpreted using appropriate soil model. It is also important to identify parameters and soil model involve in prediction real soil problem. The sand layer overlaid clay layer soil is modelled with Mohr-Coulomb and Drucker-Prager criterion. The bearing capacity in loaddisplacement analysis from COMSOL Multiphysics is obtained and presented. In addition the stress distribution and evolution of plastic strain for each thickness ratio below centre of footing are investigated. The results indicate the linear relation on load-displacement which have similar trend for both soil models while stress and plastic strain increase as thickness ratio increase.

Seasonal dynamics in wheel load-carrying capacity of a loam soil in the Swiss Plateau

DEFF Research Database (Denmark)

Gut, S.; Chervet, A.; Stettler, Matthias

2015-01-01

on in situ measurements of h, measurements of precompression stress at various h and simulations of soil stress. In this work, we concentrated on prevention of subsoil compaction. Calculations were made for different tyres (standard and low-pressure top tyres) and for soil under different tillage......Subsoil compaction is a major problem in modern agriculture caused by the intensification of agricultural production and the increase in weight of agricultural machinery. Compaction in the subsoil is highly persistent and leads to deterioration of soil functions. Wheel load-carrying capacity (WLCC......) is defined as the maximum wheel load for a specific tyre and inflation pressure that does not result in soil stress in excess of soil strength. The soil strength and hence WLCC is strongly influenced by soil matric potential (h). The aim of this study was to estimate the seasonal dynamics in WLCC based...

Measuring P availability in soils fertilized with water-soluble P fertilizers using 32P methodologies

International Nuclear Information System (INIS)

McLaughlin, M.J.

2002-01-01

Isotope exchange kinetics was used in conjunction with standard procedures for assessing soil P status in soils fertilized with soluble phosphatic fertilizers. Soil samples were collected before fertilizer application in year 1 (one) from 23 of the 30 sites of the National Reactive Phosphate Rock project. Soil phosphorus test values were plotted against indices of pasture response to applied fertilizer, to assess the effectiveness of the various soil tests to predict site responsiveness to applied fertilizer. Isotopically exchangeable P was only weakly related to other measures of available P, with resin P having the best relationship with E values. In some samples, very large values for isotopically exchangeable P (E values) were determined in relation to P extractable by all reagents. Examination of the data however, revealed that all the samples with large E values in relation to extractable P had very low equilibrium concentrations of solution P and high buffering capacities. The best soil test, Bray 1, could account for only 50% of the variation in plant responsiveness to applied fertilizer, with Olsen and Resin tests slightly worse at 41% and the isotopic procedure at 39%. (author)

EFFECT OF DIFFERENT LEVELS AGROECOLOGICAL LOADS ON BIOCHEMICAL CHARACTERISTICS OF SOIL

Directory of Open Access Journals (Sweden)

A. V. Shchur

2016-01-01

Full Text Available Aim. To study the effect of different levels of agri-environmental loads on the enzymatic activity of the soil.Methods. Isolation of soil fauna was conducted by thermogradient. Ecological characteristics of soil biota community was determined by ecological indices. The enzymatic activity of soil under different crops and at different levels of agri-environmental loads in our experiments was determined by methods proven in the laboratory soil enzymology Institute of Experimental Botany name V.F. Kuprevich and Belorussian Research Institute for Soil Science and Agricultural Chemistry.Results. Community soil biota is polydominant character, as evidenced by the values of environmental indices. It does not set a significant impact on the community agrotechnological loads of soil micro and mesofauna. Absolute figures soil phosphatase activity averaged over all embodiments without recourse formation were higher by 63% compared with plowing. Invertase and catalase activity was much higher in stubble on all variants of the experiment and selection of terms. The content of peroxidase lower under pure steam. The laws have taken place in respect of peroxidase activity, marked for polifenoloksidase activity.Main conclusion. There was no major change in the ecological characteristics of soil biota. In the enzymatic activity of soil influenced by sampling time, fertilizer system, soil tillage methods and cultivated crops.

Influence of loading rate and modes on infiltration of treated wastewater in soil-based constructed wetland.

Science.gov (United States)

Bisone, Sara; Gautier, Mathieu; Masson, Matthieu; Forquet, Nicolas

2017-01-01

Over the last 10 years soil-based constructed wetlands for discharge of treated wastewater (TWW) are commonly presented as a valuable option to provide tertiary treatment. The uncomplete knowledge in soil modifications and a lack of clear design practices laid the foundation of this work. The aim of this study was to determine optimal hydraulic loads and to observe the main critical parameters affecting treating performances and hydraulic loads acceptance. For this purpose, a soil rich in clay and backfill was chosen to perform column infiltration tests with TWW. Two loading rates and two loading modes were compared to study the influence of an intermittent feeding. Inlet and outlet waters were periodically analysed and columns were instrumented with balances, tensiometers, O 2 and temperature probes. Soil physico-chemical characteristics were also taken into account to better understand the modification of the soil. One of the main expectations of tertiary treatment is to improve phosphate removal. A particular attention was thus given to phosphorus retention. The interest of an intermittent feeding in presence of a soil with high clay content was showed. This study highlighted that an intermittent feeding could make possible the use of a clay-rich soil for water infiltration.

Physical scale modeling of single free head piles under lateral loading in cohesive soils

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Edgar Leonardo Salamanca-Medina

2017-06-01

Full Text Available This paper presents the results of the small scale modeling of free head wood piles under horizontal loading in cohesive soils, tested in order to compare the results with analytical models proposed by various authors. Characteristic Load (CLM and P-Y Curves methods were used for the prediction of lateral deflections at the head of the piles and the method proposed by Broms for estimating the ultimate lateral load. These predictions were compared with the results of the physical modeling, obtaining a good approximation between them.

Performance of Geosynthetic-Reinforced Soils Under Static and Cyclic Loading

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M. Touahmia

2017-04-01

Full Text Available This paper investigates and discusses the composite behavior of geosynthetic reinforced soil mass. It presents the results of a series of large-scale laboratory tests supported by analytical methods to examine the performance of geogrid reinforcement subjected to static and cyclic pullout loading. The testing equipment and procedures used for this investigation are outlined. The results show that geosynthetic reinforcement can mobilize great resistance to static pulling load under high confining pressures. The reinforcement exhibits gradual deformation under cyclic loading showing no sign of imminent pullout failure for all levels of applied loads. In general, the results demonstrate that geosynthetic can be used in situations where loads are non-static, although care will be required in ensuring that appropriate factors of safety are applied to control the resulting deformation. A simplified analytical model for calculating the pulling capacity of geosynthetic reinforcement is proposed.

Evaluating DEM results with FEM perspectives of load : soil interaction

NARCIS (Netherlands)

Tadesse, D.

2004-01-01

Keywords: Load - soil interaction, soil structure, soil mechanical properties, FEM (Finite Element Method), Plaxis (Finite Element Code), granular particles, shear stress, DEM (Distinct Element Method),

Numerical Simulation for the Soil-Pile-Structure Interaction under Seismic Loading

Directory of Open Access Journals (Sweden)

Lifeng Luan

2015-01-01

Full Text Available Piles are widely used as reinforcement structures in geotechnical engineering designs. If the settlement of the soil is greater than the pile, the pile is pulled down by the soil, and negative friction force is produced. Previous studies have mainly focused on the interaction of pile-soil under static condition. However, many pile projects are located in earthquake-prone areas, which indicate the importance of determining the response of the pile-soil structure under seismic load. In this paper, the nonlinear, explicit, and finite difference program FLAC3D, which considers the mechanical behavior of soil-pile interaction, is used to establish an underconsolidated soil-pile mode. The response processes of the pile side friction force, the pile axial force, and the soil response under seismic load are also analyzed.

Assessing the long term impact of phosphorus fertilization on phosphorus loadings using AnnAGNPS.

Science.gov (United States)

Yuan, Yongping; Bingner, Ronald L; Locke, Martin A; Stafford, Jim; Theurer, Fred D

2011-06-01

High phosphorus (P) loss from agricultural fields has been an environmental concern because of potential water quality problems in streams and lakes. To better understand the process of P loss and evaluate the effects of different phosphorus fertilization rates on phosphorus losses, the USDA Annualized AGricultural Non-Point Source (AnnAGNPS) pollutant loading model was applied to the Ohio Upper Auglaize watershed, located in the southern portion of the Maumee River Basin. In this study, the AnnAGNPS model was calibrated using USGS monitored data; and then the effects of different phosphorus fertilization rates on phosphorus loadings were assessed. It was found that P loadings increase as fertilization rate increases, and long term higher P application would lead to much higher P loadings to the watershed outlet. The P loadings to the watershed outlet have a dramatic change after some time with higher P application rate. This dramatic change of P loading to the watershed outlet indicates that a "critical point" may exist in the soil at which soil P loss to water changes dramatically. Simulations with different initial soil P contents showed that the higher the initial soil P content is, the less time it takes to reach the "critical point" where P loadings to the watershed outlet increases dramatically. More research needs to be done to understand the processes involved in the transfer of P between the various stable, active and labile states in the soil to ensure that the model simulations are accurate. This finding may be useful in setting up future P application and management guidelines.

An experimental study on mass loading of soil particles on plant surfaces

International Nuclear Information System (INIS)

Li, J. G.; Gerzabek, M. H.; Mueck, K.

1994-01-01

Radionuclide contaminated soil adhered to plant surfaces can contribute to human ingestion dose. To determine this contribution, a method of 46 Sc neutron activation analysis was established and tested, by which a detection limit of 0.05 mg soil per g dry plant biomass can be obtained. In the field and greenhouse experiment the mass loading of soil on ryegrass (Lolium perenne L.) and broadbean (Vicia faba L.) was investigated and the contribution from rainsplash and wind erosion were evaluated separately. Soil retained on plant surfaces in field conditions in Seibersdorf/Austria was 5.77 ± 1.44 mg soil per g dry plant for ryegrass and 9.51 ± 0.73 mg soil per g dry plant for broadbean. Estimates of contribution from rainsplash and wind erosion to soil contamination of plants during the experimental period are 68 % and 32 % for broadbean 47 % and 53 % for ryegrass respectively. Mass loading results from field studies indicate that soil adhesion on plant surfaces can contribute up to 23 % of plant 137 Cs contamination, the transfer factors modified by mass loading decline differently, depending on 137 Cs concentration of the soil and the soil mass adhered to plant surfaces. (author)

Physical Modelling of Cyclic Laterally Loaded Pile in Cohesionless Soil

DEFF Research Database (Denmark)

Hansen, Mette; Wolf, Torben K.; Rasmussen, Kristian L.

Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical in the service......Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical...... in the serviceability limit state. In this paper small-scale testing of a pile subjected to cyclic, lateral loading is treated in order to investigate the effect of cyclic loading. The test setup, which is an improvement of a previous setup, is described and the first results of testing are compared with previous...

Laboratory Testing of Cyclic Laterally Loaded Pile in Cohesionless Soil

DEFF Research Database (Denmark)

Roesen, Hanne Ravn; Ibsen, Lars Bo; Hansen, Mette

2013-01-01

Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical in the service......Offshore wind turbines are normally founded with large diameter monopiles and placed in rough environments subjected to variable lateral loads from wind and waves. A long-term lateral loading may create rotation (tilt) of the pile by change in the pile-soil system which is critical...... in the serviceability limit state. In this paper small-scale testing of a pile subjected to cyclic, lateral loading is treated in order to investigate the effect of cyclic loading. The test setup, which is an improvement of a previous setup, is described and the first results of testing are compared with previous...

Phosphorous loads evaluation from soil

International Nuclear Information System (INIS)

Mezzanotte, V.

1996-01-01

With reference to the well known difficulty of quantifying non point phosphorous loads, as well as to their growing relative importance where point source leads decrease, a literature review has been carried out concerning soil export coefficients. On such basis, the values which seem to be the most appropriate for Italy have been estimated for different land use categories. The main mechanisms determining non point phosphorous load generation and the factors affecting their importance are also described. In the end, criteria for estimating the importance of non point sources in a basin are suggested to be used for deciding whether a traditional, parametric assessment (inevitably involving a certain error) can be acceptable or experimental measures are needed

Acid loading test (pH)

Science.gov (United States)

... this page: //medlineplus.gov/ency/article/003615.htm Acid loading test (pH) To use the sharing features on this page, please enable JavaScript. The acid loading test (pH) measures the ability of the ...

Modelling of pile load tests in granular soils : Loading rate effects

NARCIS (Netherlands)

Nguyen, T.C.

2017-01-01

People have used pile foundations throughout history to support structures by transferring
loads to deeper and stronger soil layers. One of the most important questions during the design of the pile foundation is the bearing capacity of the pile. The most reliable method for determining the

An experimental study on mass loading of soil particles on plant surfaces

International Nuclear Information System (INIS)

Li, J.; Gerzabek, M.H.; Mueck, K.

1994-03-01

Radionuclide contaminated soil adhered to plant surfaces can contribute to human ingestion dose. To determine this contribution, a method of 46 Sc neutron activation analysis was established and tested, by which a detection limit of 0.05 mg soil per g dry plant biomass can be obtained. In the field and greenhouse experiment the mass loading of soil on ryegrass (Lolium perenne L.) and broad bean (Vicia faba L.) was investigated and the contribution from rainsplash and wind erosion were evaluated separately. Soil retained on plant surfaces in field conditions in Seibersdorf/Austria was 5.77 ± 1.44 mg soil per g dry plant for ryegrass and 9.51 ± 0.73 mg soil per g dry plant for broad bean. Estimates of contribution from rainsplash and wind erosion to soil contamination of plant during the experimental period are 68 % and 32 % for broadbean, 47 % and 53 % for ryegrass, respectively. Mass loading results from field studies indicate that soil adhesion on plant surfaces can contribute up to 23 % of plant 137 Cs contamination, the transfer factors modified by mass loading decline differently, depending on 137 Cs concentration of the soil and the soil mass adhered to plant surfaces. (authors)

Analysis of uplift loads of precast-concrete piles in porous soils

Directory of Open Access Journals (Sweden)

Stélio Maia Menezes

2006-01-01

Full Text Available This paper presents the analysis of uplift load tests in three precast-concrete piles carried out in a collapsible sandy soil. The piles with 12 meters (m length and 0.17 x 0.17 square meter (m2 cross section were instrumented with strain gauges, in order to know the load transfer in depth. Three tests performed in a slow maintained load way were conducted in a natural condition of moisture content soil. A fourth test was carried out after the previous soaking of the soil around the pile head. The tests were performed in the experimental research site at the Universidade Estadual Paulista “Júlio de Mesquita Filho” (Unesp. The results obtained were evaluated by analytical and empirical methods.

Methods of pH determination in Calcareous soils of Oman: The effect of Electrolyte and soil solution ratio

International Nuclear Information System (INIS)

Al-Busaidi, A.; Cookson, P.

2002-01-01

Determination of pH assists in understanding many reactions that occur in soil. Soil pH values are highly sensitive to the procedure used for determination. In this study, pH was measured in different electrolytes [distilled water (pHw), 0.01MCaCl2 (pHCa), 1MKCl (pHk), and 0.01MBaCl2 (pHba)] with different soil: electrolyte ratios (i.e. 1:1, 1:2.5 and 1:5). The objective was to determine the effect of each electrolyte and dilution ratio on pH of saline and non-saline soils from Oman. It was found that ph values varied significantly between electrolytes and with different dilution ratios. Linear regression equations were generated between electrolytes, dilution ratios and were mostly significant. Soil pH values determined in different electrolytes were significantly interrelated. Water appeared as a highly suitable solvent for soil pH measurements because it is simple and values familiar to soil users. However, alkaline errors and electrode instabilities due to liquid junction and soluble salt effects, affected soil pH measurements, especially in water, and resulted in alkaline errors during pH measurements. Errors were minimized when pH was measured in electrolytes rather than in water. (author)

Mining soil phosphorus by zero P-application: an effective method to reduce the risk of P loading to surface water

NARCIS (Netherlands)

Salm, van der C.; Chardon, W.J.; Koopmans, G.F.

2007-01-01

This study aims to find field evidence for the effectiveness of P-mining to reduce the risk of P leaching to surface water. In 2002, a P-mining was conducted on four grassland sites in the Netherlands on sand (two sites), peat and clay soils. The mining plots received no P and an annual N surplus of

Soil pH Mapping with an On-The-Go Sensor

OpenAIRE

Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

2011-01-01

Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH ManagerTM, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH ManagerTM under ...

High-Resolution Denitrification Kinetics in Pasture Soils Link N2O Emissions to pH, and Denitrification to C Mineralization.

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Md Sainur Samad

Full Text Available Denitrification in pasture soils is mediated by microbial and physicochemical processes leading to nitrogen loss through the emission of N2O and N2. It is known that N2O reduction to N2 is impaired by low soil pH yet controversy remains as inconsistent use of soil pH measurement methods by researchers, and differences in analytical methods between studies, undermine direct comparison of results. In addition, the link between denitrification and N2O emissions in response to carbon (C mineralization and pH in different pasture soils is still not well described. We hypothesized that potential denitrification rate and aerobic respiration rate would be positively associated with soils. This relationship was predicted to be more robust when a high resolution analysis is performed as opposed to a single time point comparison. We tested this by characterizing 13 different temperate pasture soils from northern and southern hemispheres sites (Ireland and New Zealand using a fully automated-high-resolution GC detection system that allowed us to detect a wide range of gas emissions simultaneously. We also compared the impact of using different extractants for determining pH on our conclusions. In all pH measurements, soil pH was strongly and negatively associated with both N2O production index (IN2O and N2O/(N2O+N2 product ratio. Furthermore, emission kinetics across all soils revealed that the denitrification rates under anoxic conditions (NO+N2O+N2 μmol N/h/vial were significantly associated with C mineralization (CO2 μmol/h/vial measured both under oxic (r2 = 0.62, p = 0.0015 and anoxic (r2 = 0.89, p<0.0001 conditions.

Determination and Distribution of Critical Loads: Application to the Forest Soils in the Autonomous Region of Madrid

International Nuclear Information System (INIS)

Sousa, M.; Schmid, T.; Rabago, I.

2000-01-01

The critical loads of acidity and sulphur have been determined for forest soils within the north and northwest of the Autonomous Region of Madrid. The SMB-CCE and SMB-PROFILE steady state models have been applied using a 1 km x 1 km resolution. The forest ecosystems have been characterised according to the soil and forest type, slope and climatic data using a Geographic Information System. In order to estimate the critical loads, processes such as weathering rate of the parent material, atmospheric deposition. critical alkalinity leaching rate and nutrients absorbed by the vegetation have been considered. In general the forest soils present high critical load values for acidity and sulphur. The more sensitive zones are found in the north of the Sierra of Guadarrama. Independent of the applied methods, the results are associated to the types of soils where Leptosols have the lowest, Cambisoles and Regosoles intermediate and Luvisoles the most elevated values. (Author) 40 refs

Identification of soil P fractions that are associated with P loss from surface runoff under various cropping systems and fertilizer rates on sloped farmland.

Science.gov (United States)

Li, Xinghua; Wang, Baona; Yang, Tewu; Zhu, Duanwei; Nie, Zhongnan; Xu, Junchi

2017-01-01

Soil phosphorus (P) fractions and runoff P concentration were measured to understand the fate of soil P entering surface runoff water during summer cropping season of different double cropping systems under two fertilizer regimes. The dominant form of runoff P was particulate P (PP). Runoff total P (TP) was higher at the vegetative growth stage and lower at the crop reproductive stage. TP and PP were derived mainly from soil Olsen-P, Al-P and Fe-P and amounts increased with sediment content in runoff water. Runoff P discharge was closely related to the changes in soil P forms. Soil Olsen-P, mainly consisting of some Ca2-P and Al-P, was increased by elevating fertilizer rate. Along with crop growth, there were active interconversions among Olsen-P, Org-P, Fe-P and O-Al-P in the soil, and some available P converted into Ca10-P, with O-Fe-P possibly being a transitional form for this conversion. The oilseed rape/corn system had less runoff TP at the early stage, and wheat/sweet potato system had a lower runoff P at the late stage. Intercropping corn with sweet potato in the field with oilseed rape as a previous crop may be helpful for alleviating runoff P load during the summer in this region.

Identification of soil P fractions that are associated with P loss from surface runoff under various cropping systems and fertilizer rates on sloped farmland.

Directory of Open Access Journals (Sweden)

Xinghua Li

Full Text Available Soil phosphorus (P fractions and runoff P concentration were measured to understand the fate of soil P entering surface runoff water during summer cropping season of different double cropping systems under two fertilizer regimes. The dominant form of runoff P was particulate P (PP. Runoff total P (TP was higher at the vegetative growth stage and lower at the crop reproductive stage. TP and PP were derived mainly from soil Olsen-P, Al-P and Fe-P and amounts increased with sediment content in runoff water. Runoff P discharge was closely related to the changes in soil P forms. Soil Olsen-P, mainly consisting of some Ca2-P and Al-P, was increased by elevating fertilizer rate. Along with crop growth, there were active interconversions among Olsen-P, Org-P, Fe-P and O-Al-P in the soil, and some available P converted into Ca10-P, with O-Fe-P possibly being a transitional form for this conversion. The oilseed rape/corn system had less runoff TP at the early stage, and wheat/sweet potato system had a lower runoff P at the late stage. Intercropping corn with sweet potato in the field with oilseed rape as a previous crop may be helpful for alleviating runoff P load during the summer in this region.

Pressure vessels supported in the soil submitted to axissymetrical loads

International Nuclear Information System (INIS)

Gouvea, J.P. de; Bevilacqua, L.

1982-01-01

A pressure vessel, spherical segment or vertical cylinder, is supported in the soil and submitted to axissymetrical loads. The soil is considered as a semi-infinite elastic solid and the support as a lattice. The method of rigidity is used. (E.G.) [pt

Carbon-cycle effects of differences in soil moisture and soil extracellular enzyme activity at sites representing different land-use histories in high-elevation Ecuadorian páramo landscapes

Science.gov (United States)

McKnight, J.; Harden, C. P.; Schaeffer, S. M.

2016-12-01

Ecuadorian páramo grasslands are important regional soil carbon sinks. In the páramo of the Mazar Wildlife Reserve, differences in soil carbon content among different types of land use may reflect changes in soil carbon-acquisition related microbial enzyme activity after land cover and soil moisture are altered; however, this hypothesis has not been tested explicitly for Ecuadorian páramos. This study used a fluorescence enzyme assay to assess the activities of four different extracellular enzymes representing carbon acquisition: α-glucosidase, β-glucosidase, β-D-cellulobiohydrolase, and β-xylosidase in Andean páramo soils. Acquisition activities were also measured for nitrogen (N-acetyl-β-glucosidase and leucine aminopeptidase) and phosphorus (phosphatase) to assess stoichiometric differences between land-uses, which can affect soil microbial activity related to carbon acquisition. Soils were analyzed from four land uses: native forest, grass páramo, recently burned grass páramo, and non-native pine plantation. Carbon acquisition activity was highest at the pine site (678 nmol h-1 g-1) and lowest at the recently burned páramo site (252 nmol h-1 g-1), indicating the lowest and highest available soil carbon, respectively. Carbon-acquisition EE activity was significantly higher at the grass páramo site (595 nmol h-1 g-1) than at the recently burned páramo and native forest sites. At the grass páramo site, a history of burning as a management strategy and high carbon-acquisition EE activity could indicate the presence of pyrogenic soil organic matter, which is more resistant to microbial decomposition. Soils at the native forest and both grassland sites were phosphorus limited, and soil at the pine site had higher nitrogen-acquisition activity, indicative of a shift to nitrogen-limited soil stoichiometric conditions. To our knowledge these are the first data reported for soil extracellular enzyme activities for Ecuadorian páramos.

Assessment of p-y curves from numerical methods for a non-slender monopile in cohesionless soil

Energy Technology Data Exchange (ETDEWEB)

Ibsen, L. B.; Ravn Roesen, H. [Aalborg Univ. Dept. of Civil Engineering, Aalborg (Denmark); Hansen, Mette; Kirk Wolf, T. [COWI, Kgs. Lyngby (Denmark); Lange Rasmussen, K. [Niras, Aalborg (Denmark)

2013-06-15

In current design the monopile is a widely used solution as foundation of offshore wind turbines. Winds and waves subject the monopile to considerable lateral loads. The behaviour of monopiles under lateral loading is not fully understood and the current design guidances apply the p-y curve method in a Winkler model approach. The p-y curve method was originally developed for jag-piles used in the oil and gas industry which are much more slender than the monopile foundation. In recent years the 3D finite element analysis has become a tool in the investigation of complex geotechnical situations, such as the laterally loaded monopile. In this paper a 3D FEA is conducted as basis of an extraction of p-y curves, as a basis for an evaluation of the traditional curves. Two different methods are applied to create a list of data points used for the p-y curves: A force producing a similar response as seen in the ULS situation is applied stepwise; hereby creating the most realistic soil response. This method, however, does not generate sufficient data points around the rotation point of the pile. Therefore, also a forced horizontal displacement of the entire pile is applied, whereby displacements are created over the entire length of the pile. The response is extracted from the interface and the nearby soil elements respectively, as to investigate the influence this has on the computed curves. p-y curves are obtained near the rotation point by evaluation of soil response during a prescribed displacement but the response is not in clear agreement with the response during an applied load. Two different material models are applied. It is found that the applied material models have a significant influence on the stiffness of the evaluated p-y curves. The p-y curves evaluated by means of FEA are compared to the conventional p-y curve formulation which provides a much stiffer response. It is found that the best response is computed by implementing the Hardening Soil model and

Relation between soil P test values and mobilization of dissolved and particulate P from the plough layer of typical Danish soils from a long-term field experiment with applied P fertilizers

DEFF Research Database (Denmark)

Glaesner, N.; Kjaergaard, C.; Rubaek, G. H.

2013-01-01

Accumulation of phosphorus (P) in agricultural topsoils can contribute to leaching of P which may cause eutrophication of surface waters. An understanding of P mobilization processes in the plough layer is needed to improve agricultural management strategies. We compare leaching of total dissolved...... and particulate P through the plough layer of a typical Danish sandy loam soil subjected to three different P fertilizer regimes in a long-term field experiment established in 1975. The leaching experiment used intact soil columns (20cm diameter, 20cm high) during unsaturated conditions. The three soils had small...

AGROPHYSICAL ASPECTS OF TECHNOLOGICAL LOAD REGULATION ON SOIL COVER IN THE MODERN AGROLANDSCAPES

Directory of Open Access Journals (Sweden)

Barvinskyi A.V.

2016-05-01

Full Text Available Modern agricultural landuseof researched Tetiivskyi-Boguslavskyi nature-agricultural district of Kyiv region is characterized by high technological loading on the soil covering, associated with the transformation of lands structure and sowing areas of crops under the influence of market situations. The high level of technological loading on land resources causes the development of degradation processes, and as a result – reduced lands productivity. The main reasons are: unbalanced development of the productive forces and exhausting exploitation of land resources, producers ignoring of environmental imperatives, technical, technological and organizational backwardness of agricultural production; embryonic nature of ecological and economical mechanism of land use and realization of land protection measures, the lack of perfect legal framework of regulating and management of resource- ecological security at national, regional and local levels. Increasing of anthropogeneous pressure on soil (excessive soil tillage in agricultural landscapes, ecologically unsustainable use of agricultural chemicals, high intensity of heavy agricultural machinery, etc. leads to increase of degradation processes almost on the all area of arable land (Medvedev, 1994. So important is the continuous monitoring of agrophysical condition of soils and development of scientific and practical foundations of optimizing the physical parameters of fertility. The environmentally unbalanced application of anthropogeneous factors results in agrophysical degradation of arable lands, what is displaied in top soil overcompaction.Experimentally found that depending on how the agricultural land use equilibrium bulk density of the gray forest soils varies between 1,35-1,58 g/cm3, dark-gray forest soils - 1,36-1,44, podzolized chernozem - 1,26-1,33, typical chernozem- 1,09-1,18 g/cm3, that indicating the imbalance of soil-physical factors, a significant deviation from the requirements of

Comparison of point-source pollutant loadings to soil and groundwater for 72 chemical substances.

Science.gov (United States)

Yu, Soonyoung; Hwang, Sang-Il; Yun, Seong-Taek; Chae, Gitak; Lee, Dongsu; Kim, Ki-Eun

2017-11-01

Fate and transport of 72 chemicals in soil and groundwater were assessed by using a multiphase compositional model (CompFlow Bio) because some of the chemicals are non-aqueous phase liquids or solids in the original form. One metric ton of chemicals were assumed to leak in a stylized facility. Scenarios of both surface spills and subsurface leaks were considered. Simulation results showed that the fate and transport of chemicals above the water table affected the fate and transport of chemicals below the water table, and vice versa. Surface spill scenarios caused much less concentrations than subsurface leak scenarios because leaching amounts into the subsurface environment were small (at most 6% of the 1 t spill for methylamine). Then, simulation results were applied to assess point-source pollutant loadings to soil and groundwater above and below the water table, respectively, by multiplying concentrations, impact areas, and durations. These three components correspond to the intensity of contamination, mobility, and persistency in the assessment of pollutant loading, respectively. Assessment results showed that the pollutant loadings in soil and groundwater were linearly related (r 2  = 0.64). The pollutant loadings were negatively related with zero-order and first-order decay rates in both soil (r = - 0.5 and - 0.6, respectively) and groundwater (- 1.0 and - 0.8, respectively). In addition, this study scientifically defended that the soil partitioning coefficient (K d ) significantly affected the pollutant loadings in soil (r = 0.6) and the maximum masses in groundwater (r = - 0.9). However, K d was not a representative factor for chemical transportability unlike the expectation in chemical ranking systems of soil and groundwater pollutants. The pollutant loadings estimated using a physics-based hydrogeological model provided a more rational ranking for exposure assessment, compared to the summation of persistency and transportability scores in

Comparing measured with simulated vertical soil stress under vehicle load

DEFF Research Database (Denmark)

Keller, Thomas; Lamandé, Mathieu; Arvidsson, Johan

The load transfer within agricultural soil is typically modelled on the basis of the theory of stress transmission in elastic media, usually in the semi-empirical form that includes the “concentration factor” (v). Measurements of stress in soil are needed to evaluate model calculations, but may...

A literature study on the effects of cyclic lateral loading of monopiles in cohesionless soils

Energy Technology Data Exchange (ETDEWEB)

Lange Rasmussen, K. [Niras, Aalborg (Denmark); Hansen, Mette; Kirk Wolf, T. [COWI, Kgs. Lyngby, (Denmark); Ibsen, L.B.; Ravn Roesen, H. [Aalborg Univ.. Dept. of Civil Engineering, Aalborg (Denmark)

2013-06-15

Today, monopiles are the most typical foundation for offshore wind turbines. During their lifetime large diameter, stiff piles are subjected to millions of small cyclic loads due to environmental forces. The long-term cyclic loading can change the granular structure of the soil surrounding the pile. This may change the stiffness of the soil-pile system and create an accumulated rotation of the pile. The behaviour of the soil-pile system is very complex and the influence of soil parameters, number of load cycles, and size, amplitude and characteristic of the load are examined, as they all contribute to the rotation and the change in stiffness. The scope of this article is to outline current design methods and the state of the art knowledge within the subject of long-term cyclic, lateral loading of piles. (Author)

A conceptual framework: redifining forests soil's critical acid loads under a changing climate

Science.gov (United States)

Steven G. McNulty; Johnny L. Boggs

2010-01-01

Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it...

Degradation of [14C]isofenphos in soil in the laboratory under different soil pH's, temperatures, and moistures

International Nuclear Information System (INIS)

Abou-Assaf, N.; Coats, J.R.

1987-01-01

The effects of three soil pH's, three soil temperatures, and three soil moistures on [ 14 C]isofenphos degradation were investigated. All three factors interacted strongly and significantly affected the persistence of isofenphos as well as the formation of the degradation products (p less than 1%). Isofenphos degradation was greatest at the higher temperatures 35 0 C greater than 25 0 C greater than 15 0 C (except under alkaline pH's), medium moisture 25% greater than 30% greater than 15%, and in both alkaline (pH = 8) and acidic soils (pH = 6) compared with neutral soil (pH = 7). Isofenphos oxon formation was greatest at higher temperatures 35 0 C compared with 25 0 C and 15 0 C, in acidic soil greater than neutral soil greater than alkaline soil, and under high moisture (30%) compared with the 15% and 22.5% moistures. The formation of soil-bound residues was greatest at higher temperatures 35 0 C greater than 25 0 C greater than 15 0 C, higher moisture 30% compared with 15% and 22.5%, and in alkaline soil compared with neutral and acidic soils

Dairy heifer manure management, dietary phosphorus, and soil test P effects on runoff phosphorus.

Science.gov (United States)

Jokela, William E; Coblentz, Wayne K; Hoffman, Patrick C

2012-01-01

Manure application to cropland can contribute to runoff losses of P and eutrophication of surface waters. We conducted a series of three rainfall simulation experiments to assess the effects of dairy heifer dietary P, manure application method, application rate, and soil test P on runoff P losses from two successive simulated rainfall events. Bedded manure (18-21% solids) from dairy heifers fed diets with or without supplemental P was applied on a silt loam soil packed into 1- by 0.2-m sheet metal pans. Manure was either surface-applied or incorporated (Experiment 1) or surface-applied at two rates (Experiment 2) to supply 26 to 63 kg P ha. Experiment 3 evaluated runoff P from four similar nonmanured soils with average Bray P1-extractable P levels of 11, 29, 51, and 75 mg kg. We measured runoff quantity, total P (TP), dissolved reactive P (DRP), and total and volatile solids in runoff collected for 30 min after runoff initiation from two simulated rain events (70 mm h) 3 or 4 d apart. Manure incorporation reduced TP and DRP concentrations and load by 85 to 90% compared with surface application. Doubling the manure rate increased runoff DRP and TP concentrations an average of 36%. In the same experiment, P diet supplementation increased water-extractable P in manure by 100% and increased runoff DRP concentration threefold. Concentrations of solids, TP, and DRP in runoff from Rain 2 were 25 to 75% lower than from Rain 1 in Experiments 1 and 2. Runoff DRP from nonmanured soils increased quadratically with increasing soil test P. These results show that large reductions in P runoff losses can be achieved by incorporation of manure, avoiding unnecessary diet P supplementation, limiting manure application rate, and managing soils to prevent excessive soil test P levels. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

How changing root system architecture can help tackle a reduction in soil phosphate (P) levels for better plant P acquisition

KAUST Repository

HEPPELL, J.

2014-06-24

© 2014 John Wiley & Sons Ltd. The readily available global rock phosphate (P) reserves may run out within the next 50-130 years, causing soils to have a reduced P concentration which will affect plant P uptake. Using a combination of mathematical modelling and experimental data, we investigated potential plant-based options for optimizing crop P uptake in reduced soil P environments. By varying the P concentration within a well-mixed agricultural soil, for high and low P (35.5-12.5mgL-1 respectively using Olsen\\'s P index), we investigated branching distributions within a wheat root system that maximize P uptake. Changing the root branching distribution from linear (evenly spaced branches) to strongly exponential (a greater number of branches at the top of the soil) improves P uptake by 142% for low-P soils when root mass is kept constant between simulations. This causes the roots to emerge earlier and mimics topsoil foraging. Manipulating root branching patterns, to maximize P uptake, is not enough on its own to overcome the drop in soil P from high to low P. Further mechanisms have to be considered to fully understand the impact of P reduction on plant development.

Application of wastewater with high organic load for saline-sodic soil reclamation focusing on soil purification ability

Directory of Open Access Journals (Sweden)

M.A. Kameli

2017-04-01

Full Text Available Fresh water source scarcity in arid and semiarid area is limitation factor for saline-sodic soil reclamation. The reusing of agricultural drainage and industrial wastewater are preferred strategies for combating with this concern. The objective of current study was evaluation in application of industrial sugar manufacture wastewater due to high soluble organic compounds in saline-sodic and sodic soil. Also soil ability in wastewater organic compounds removal was second aim of present study. Saline-sodic and sodic soil sample was leached in soil column by diluted wastewater of amirkabir sugar manufacture in Khuzestan Province of Iran at constant water head. Sodium, electric conductivity and chemical oxygen demand of soil column leachate were measured per each pore volume. The experimental kinetics of wastewater organic compounds on two saline-sodic and sodic soil were also investigated by three pseudo second order, intra particle diffusion and elovich model. The results of current study showed that electric conductivity of saline-sodic soil was decreased to 90% during 3 initial pore volumes, from other side exchangeable sodium percent of saline-sodic and sodic soil decreased 30 and 71 percent, respectively. There were no significant different between wastewater chemical oxygen demand removal by saline-sodic and sodic soil in both batch and column studies. Wastewater chemical oxygen demand was decreased to 35% during pass through soil column. The results showed that the adsorption kinetics of wastewater organic compounds were best fitted by the pseudo-second order model with 99 percent correlation coefficient (r2=0.99%.

Aluminium tolerance and high phosphorus efficiency helps Stylosanthes better adapt to low-P acid soils.

Science.gov (United States)

Du, Yu-Mei; Tian, Jiang; Liao, Hong; Bai, Chang-Jun; Yan, Xiao-Long; Liu, Guo-Dao

2009-06-01

Stylosanthes spp. (stylo) is one of the most important pasture legumes used in a wide range of agricultural systems on acid soils, where aluminium (Al) toxicity and phosphorus (P) deficiency are two major limiting factors for plant growth. However, physiological mechanisms of stylo adaptation to acid soils are not understood. Twelve stylo genotypes were surveyed under field conditions, followed by sand and nutrient solution culture experiments to investigate possible physiological mechanisms of stylo adaptation to low-P acid soils. Stylo genotypes varied substantially in growth and P uptake in low P conditions in the field. Three genotypes contrasting in P efficiency were selected for experiments in nutrient solution and sand culture to examine their Al tolerance and ability to utilize different P sources, including Ca-P, K-P, Al-P, Fe-P and phytate-P. Among the three tested genotypes, the P-efficient genotype 'TPRC2001-1' had higher Al tolerance than the P-inefficient genotype 'Fine-stem' as indicated by relative tap root length and haematoxylin staining. The three genotypes differed in their ability to utilize different P sources. The P-efficient genotype, 'TPRC2001-1', had superior ability to utilize phytate-P. The findings suggest that possible physiological mechanisms of stylo adaptation to low-P acid soils might involve superior ability of plant roots to tolerate Al toxicity and to utilize organic P and Al-P.

Effect of pH on saturated hydraulic conductivity and soil dispersion

Energy Technology Data Exchange (ETDEWEB)

Suarez, D.L.; Roades, J.D.; Lavado, R.; Grieve, C.M.

The adverse effects of exchangeable sodium on soil hydraulic conductivity (K) are well known, but at present only sodicity and total electrolyte concentration are used in evaluating irrigation water suitability. In arid areas, high sodicity is often associatd with high dissolved carbonate and thus high pH, but in humid areas high sodicity may be associated with low pH. To evaluate the effect of pH (as an independent variable) on K, solutions with the same SAR and electrolyte level were prepared at pH 6, 7, 8, and 9. Saturated K values were determined at constant flux in columns packed at a bulk density of 1.5 Mg m/sup -3/. At pH 9, saturated K values were lower than at pH 6 for a montmorillonitic and kaolinitic soil. For a vermiculitic soil with lower organic carbon and higher silt content, pH changes did not cause large K differences. Decreases in K were not reversible on application of waters with higher electrolyte levels. The results from the K experiments were generally consistent with optical transmission measurements of dispersion. Although anion adsorption was at or below detection limits and cation exchange capacity (CEC) was only slightly dependent on pH, differences in pH effects on K among soils are likely due to differences in quantities of variable-charge minerals and organic matter.

Effects of Soil Oxygen Conditions and Soil pH on Remediation of DDT-contaminated Soil by Laccase from White Rot Fungi

Directory of Open Access Journals (Sweden)

Yuechun Zhao

2010-04-01

Full Text Available High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5–4.5.

Small-Scale Testing Rig for Long-Term Cyclically Loaded Monopiles in Cohesionless Soil

DEFF Research Database (Denmark)

Roesen, Hanne Ravn; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard

2012-01-01

, and the period of the cyclic loading. However, the design guidance on these issues is limited. Thus, in order to investigate the pile behaviour for cyclically long-term loaded monopiles, a test setup for small-scale tests in saturated dense cohesionless soil is constructed and presented in here. The cyclic...... loading is applied mechanically by means of a testing rig, where the important input parameters: mean level, amplitude, number of cycles, and period of the loading can be varied. The results from a monotonic and a cyclic loading test on an open-ended aluminium pile with diameter = 100 mm and embedded...... length = 600 mm proves that the test setup is capable of applying the cyclic long-term loading. The plastic deformations during loading depend not only on the loading applied but also of the relative density of the soil and, thus, the tests are carried out with relative densities of 77-88%, i.e. similar...

Sensitivity of soil phosphorus tests in predicting the potential risk of phosphorus loss from pasture soil

Directory of Open Access Journals (Sweden)

H. SOINNE

2008-12-01

Full Text Available The objective of this study was to examine the effects of urine and dung additions on the phosphorus (P chemistry of pasture land and to compare the sensitivity of two soil extraction methods in assessing the P-loading risk. In a field experiment, urine and dung were added to soil in amounts corresponding to single excrement portions and the soil samples, taken at certain intervals, were analysed for pHH2O, acid ammonium acetate extractable P (PAc and water extractable total P (TPw, and molybdate reactive P (MRPw. Urine additions immediately increased soil pH and MRPw, but no such response was observed in PAc extraction due to the low pH (4.65 of the extractant enhancing the resorption of P. The PAc responded to the dunginduced increase in soil total P similarly as did Pw, which suggests that both tests can serve to detect areas of high P concentration. However, water extraction was a more sensitive method for estimating short-term changes in P solubility. In pasture soils, the risk of P loss increases as a result of the interaction of urination and high P concentration in the topsoil resulting from continuous dung excretion.;

Critical loads and excess loads of cadmium, copper and lead for European forest soils

NARCIS (Netherlands)

Reinds, G.J.; Bril, J.; Vries, de W.; Groenenberg, J.E.; Breeuwsma, A.

1995-01-01

Recently, concern has arisen about the impact of the dispersion of heavy metals in Europe. Therefore, a study (ESQUAD) was initiated to assess critical loads and steady-state concentrations of cadmium, copper and lead for European forest soils. The calculation methods used strongly resemble those

Interaction of Buried Pipeline with Soil Under Different Loading Cases

Directory of Open Access Journals (Sweden)

Magura Martin

2016-09-01

Full Text Available Gas pipelines pass through different topographies. Their stress level is influenced not only by gas pressure, but also by the adjacent soil, the thickness of any covering layers, and soil movements (sinking, landslides. The stress level may be unevenly spread over a pipe due to these causes. When evaluating experimental measurements, errors may occur. The value of the resistance reserve of steel can be adjusted by a detailed analysis of any loading. This reserve can be used in the assessment of a pipeline’s actual state or in reconstructions. A detailed analysis of such loading and its comparison with the simple theory of elasticity is shown in this article.

Evaluation of the base/subgrade soil under repeated loading : phase II, in-box and ALF cyclic plate load tests.

Science.gov (United States)

2012-03-01

This research study aims at evaluating the performance of base and subgrade soil in flexible pavements under repeated loading test conditions. For this purpose, an indoor cyclic plate load testing equipment was developed and used to conduct a series ...

Estimation of the degree of soil P saturation from Brazilian Mehlich-1 P data and field investigations on P losses from agricultural sites in Minas Gerais.

Science.gov (United States)

Fischer, P; Pöthig, R; Gücker, B; Venohr, M

The degree of phosphorus saturation (DPS) of agricultural soils is studied worldwide for risk assessment of phosphorus (P) losses. In previous studies, DPS could be reliably estimated from water-soluble P (WSP) for European and Brazilian soils. In the present study, we correlated measured WSP and Mehlich-1 P (M1P) from soils of Minas Gerais (MG) and Pernambuco (PE) (R(2) = 0.94, n = 59) to create a DPS map from monitoring data. The resulting DPS map showed high spatial variability and low values of DPS (54 ± 22%, mean and standard deviation; n = 1,827). Measured soil DPS values amounted to 63 ± 14% and resulted in relatively low dissolved P concentrations measured in a surface runoff study in MG. However, fertilizer grains on the soil surface led to high WSP values (>30 mg/kg) indicating high risks of dissolved P losses. We suppose that small Oxisol particles with Fe and Al hydroxides sorbed most of the dissolved fertilizer P in runoff so that P was mainly exported in particulate form. In soils with lower contents of P sorption and binding partners, e.g. Entisols in PE, this effect may be less dominant. Consequently, superficial fertilizer effects have to be considered in addition to DPS in risk assessment of P losses from agricultural areas in Brazil.

Novel chelating agents for iron, manganese, zinc, and copper mixed fertilisation in high pH soil-less cultures.

Science.gov (United States)

López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J

2016-03-15

Studies about simultaneous fertilisation with several micronutrients have increased in recent years, as Fe, Mn and Zn deficiencies may appear in the same culture conditions. In fertigation, the replacement of sulfates by synthetic chelates is essential in areas with high pH irrigation water and substrates. Ethylenediamine-N-(2-hydroxyphenylacetic acid)-N'-(4-hydroxyphenylacetic acid) (o,p-EDDHA) and ethylenediamine disuccinic acid (EDDS) are novel chelating agents whose efficacy in simultaneous fertilisation of Zn, Mn and Cu is unknown. This work evaluates the effectiveness of both ligands compared to traditional ligands (EDTA, HEEDTA and DTPA) applied as micronutrient chelate mixtures to soybean and navy bean plants grown in soil-less cultures at high pH by analysing the SPAD and micronutrient nutritional status, including the Composition Nutritional Diagnosis (CND) analysis tool. The application of micronutrients using o,p-EDDHA was more effective in providing Mn and Zn than traditional ligands or sulfates. The application using EDDS increased the Zn nutrition. The results are well correlated with the chemical stability of the formulations. The combined application of Mn and Zn as o,p-EDDHA chelates can represent a more effective source than traditional chelates in micronutrient fertiliser mixtures in soil-less cultures at a high pH. © 2015 Society of Chemical Industry.

Soil-structure interaction for transient loads due to safety relief valve discharges

International Nuclear Information System (INIS)

Tseng, W.S.; Tsai, N.C.

1978-01-01

Dynamic responses of BWR Mark II containment structures subjected to axisymmetric transient pressure loadings due to simultaneous safety relief valve discharges were investigated using finite element analysis, including the soil-structure interaction effect. To properly consider the soil-structure interaction effect, a simplified lumped parameter foundation model and axisymmetric finite element foundation model with viscous boundary impedance are used. Analytical results are presented to demonstrate the effectiveness of the simplified foundation model and to exhibit the dynamic response behavior of the structure as the transient loading frequency and the foundation rigidity vary. The impact of the dynamic structural response due to this type of loading on the equipment design is also discussed. (Auth.)

Effect of land use on some soil chemical properties and P fractions ...

African Journals Online (AJOL)

Land use directly or indirectly affects the soil chemical properties and phosphorus fractions. Two different land use types were studied. Soil chemical analysis and phosphorus fractionation of the soils was then done and the results were highly significant (p<0.001). Total C, N and P were low under the arable land use as ...

Estimation of p,p'-DDT degradation in soil by modeling and constraining hydrological and biogeochemical controls.

Science.gov (United States)

Sanka, Ondrej; Kalina, Jiri; Lin, Yan; Deutscher, Jan; Futter, Martyn; Butterfield, Dan; Melymuk, Lisa; Brabec, Karel; Nizzetto, Luca

2018-08-01

Despite not being used for decades in most countries, DDT remains ubiquitous in soils due to its persistence and intense past usage. Because of this it is still a pollutant of high global concern. Assessing long term dissipation of DDT from this reservoir is fundamental to understand future environmental and human exposure. Despite a large research effort, key properties controlling fate in soil (in particular, the degradation half-life (τ soil )) are far from being fully quantified. This paper describes a case study in a large central European catchment where hundreds of measurements of p,p'-DDT concentrations in air, soil, river water and sediment are available for the last two decades. The goal was to deliver an integrated estimation of τ soil by constraining a state-of-the-art hydrobiogeochemical-multimedia fate model of the catchment against the full body of empirical data available for this area. The INCA-Contaminants model was used for this scope. Good predictive performance against an (external) dataset of water and sediment concentrations was achieved with partitioning properties taken from the literature and τ soil estimates obtained from forcing the model against empirical historical data of p,p'-DDT in the catchment multicompartments. This approach allowed estimation of p,p'-DDT degradation in soil after taking adequate consideration of losses due to runoff and volatilization. Estimated τ soil ranged over 3000-3800 days. Degradation was the most important loss process, accounting on a yearly basis for more than 90% of the total dissipation. The total dissipation flux from the catchment soils was one order of magnitude higher than the total current atmospheric input estimated from atmospheric concentrations, suggesting that the bulk of p,p'-DDT currently being remobilized or lost is essentially that accumulated over two decades ago. Copyright © 2018 Elsevier Ltd. All rights reserved.

The role of soil pH on soil carbonic anhydrase activity

Science.gov (United States)

Sauze, Joana; Jones, Sam P.; Wingate, Lisa; Wohl, Steven; Ogée, Jérôme

2018-01-01

Carbonic anhydrases (CAs) are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO18O fluxes to the global budget of atmospheric CO18O. The oxygen isotope signatures (δ18O) of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO18O as a tracer of land surface CO2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO2 between the different carbonate forms. In this study we investigated the CO2-H2O isotopic exchange rate (kiso) in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content) affected the relationship between kiso and CA concentration. We found that soil pH was the primary driver of kiso after CA addition and that the chemical composition (i.e. phosphate content) played only a secondary role. We also found an offset between the δ18O of the water pool with which CO2 equilibrates and total soil water (i.e. water extracted by vacuum distillation) that varied with soil texture. The reasons for this offset are still unknown.

The role of soil pH on soil carbonic anhydrase activity

Directory of Open Access Journals (Sweden)

J. Sauze

2018-01-01

Full Text Available Carbonic anhydrases (CAs are metalloenzymes present in plants and microorganisms that catalyse the interconversion of CO2 and water to bicarbonate and protons. Because oxygen isotopes are also exchanged during this reaction, the presence of CA also modifies the contribution of soil and plant CO18O fluxes to the global budget of atmospheric CO18O. The oxygen isotope signatures (δ18O of these fluxes differ as leaf water pools are usually more enriched than soil water pools, and this difference is used to partition the net CO2 flux over land into soil respiration and plant photosynthesis. Nonetheless, the use of atmospheric CO18O as a tracer of land surface CO2 fluxes requires a good knowledge of soil CA activity. Previous studies have shown that significant differences in soil CA activity are found in different biomes and seasons, but our understanding of the environmental and ecological drivers responsible for the spatial and temporal patterns observed in soil CA activity is still limited. One factor that has been overlooked so far is pH. Soil pH is known to strongly influence microbial community composition, richness and diversity in addition to governing the speciation of CO2 between the different carbonate forms. In this study we investigated the CO2–H2O isotopic exchange rate (kiso in six soils with pH varying from 4.5 to 8.5. We also artificially increased the soil CA concentration to test how pH and other soil properties (texture and phosphate content affected the relationship between kiso and CA concentration. We found that soil pH was the primary driver of kiso after CA addition and that the chemical composition (i.e. phosphate content played only a secondary role. We also found an offset between the δ18O of the water pool with which CO2 equilibrates and total soil water (i.e. water extracted by vacuum distillation that varied with soil texture. The reasons for this offset are still unknown.

Synthesis of a smart pH-responsive magnetic nanocomposite as high loading carrier of pharmaceutical agents.

Science.gov (United States)

Berah, Razieh; Ghorbani, Mohsen; Moghadamnia, Ali Akbar

2017-06-01

To create facile external controlled drug delivery system, a magnetic porous carrier based on Tin oxide nanoparticles was synthesized by an inexpensive and versatile hydrothermal strategy and used for in-vitro process. Magnetic nanocomposites were qualified by Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Vibrational Sample Magnetometer (VSM) and Transmission Electron Microscopy (TEM). Results showed that nanoparticles were synthesized successfully with good dispersion of magnetic nanoparticles in cavity, uniform particle size distribution with average size of 65nm and high magnetization of 33.75 emu/mg. Furthermore, the nano-porosity and magnetism allowed high efficiency and remote controlled drug release. In this study, anti-migraine Sumatriptan was used as drug sample and the effect of drug concentration, Fe/Sn ratio and loading time on drug absorption were investigated. The best result was checked for stability at body temperature and different body pH. The sample with drug concentration of 0.25(mg/ml), Fe/Sn=0.22 and loading time of 1.5h had the highest drug efficiency (70%). Finally, in order to simulate the in vivo process for in-vitro step, Amnion was used and drug diffusion rate was measured in different intervals and different pH values. The result illustrated that after 25h, diffusion reached 65% at pH=2 and 56% at pH=7, and then became constant. Based on the above mentioned results, the carrier has an acceptable in vitro yield and therefore could be chosen for future in vivo researches. Copyright © 2017 Elsevier B.V. All rights reserved.

The critical soil P levels for crop yield, soil fertility and environmental safety in different soil types

NARCIS (Netherlands)

Bai, Z.H.; Li, H.G.; Yang, X.Y.; Zhou, B.K.; Shi, X.J.; Wang, B.R.; Li, D.C.; Shen, J.B.; Chen, Q.; Qin, W.; Oenema, O.; Zhang, F.S.

2013-01-01

Sufficient soil phosphorus (P) is important for achieving optimal crop production, but excessive soil P levels may create a risk of P losses and associated eutrophication of surface waters. The aim of this study was to determine critical soil P levels for achieving optimal crop yields and minimal P

Influence of soil γ-irradiation and spiking on sorption of p,p'-DDE and soil organic matter chemistry.

Science.gov (United States)

Škulcová, Lucia; Scherr, Kerstin E; Chrást, Lukáš; Hofman, Jakub; Bielská, Lucie

2018-07-15

The fate of organic chemicals and their metabolites in soils is often investigated in model matrices having undergone various pre-treatment steps that may qualitatively or quantitatively interfere with the results. Presently, effects associated with soil sterilization by γ-irradiation and soil spiking using an organic solvent were studied in one freshly spiked soil (sterilization prior to contamination) and its field-contaminated (sterilization after contamination) counterpart for the model organic compound 1,1-Dichloro-2,2-bis(4-chlorophenyl)ethene (p,p'-DDE). Changes in the sorption and potential bioavailability of spiked and native p,p'-DDE were measured by supercritical fluid extraction (SFE), XAD-assisted extraction (XAD), and solid-phase microextraction (SPME) and linked to qualitative changes in soil organic matter (SOM) chemistry measured by diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy. Reduced sorption of p,p´-DDE detected with XAD and SPME was associated more clearly with spiking than with sterilization, but SFE showed a negligible impact. Spiking resulted in an increase of the DRIFT-derived hydrophobicity index, but irradiation did not. Spectral peak height ratio descriptors indicated increasing hydrophobicity and hydrophilicity in pristine soil following sterilization, and a greater reduction of hydrophobic over hydrophilic groups as a consequence of spiking. In parallel, reduced sorption of p,p´-DDE upon spiking was observed. Based on the present samples, γ-irradiation appears to alter soil sorptive properties to a lesser extent when compared to common laboratory processes such as spiking with organic solvents. Copyright © 2018. Published by Elsevier Inc.

Soil P forms and P uptake under intensive plant growth in the greenhouse

International Nuclear Information System (INIS)

Henriquez, Carlos; Killorn, Randy

2005-01-01

The concentration of available soil (P) is a function of the equilibrium established among different soil P forms through numerous and different reactions in soil. The objective of this study was to examine the changes in P forms and P supply under exhaustive extraction conditions in soils from 3 different land use areas. In order to establish a greenhouse experiment, representative soil samples (0-20 cm) were taken from three fields located adjacent to one another, in a Typic Hapludands in Costa Rica. One field was a coffee plantation (Coffea arabica var Catuai), the second a sugar cane plantation (Saccarum spp. var 611721), and the third a secondary forest. Sorghum bicolor var Glazer 41) was planted in 1-liter pots and harvested 4 times consecutively. Treatments were no P and P application (100 mg kg -1 ) for each of the different land-use soil samples. Shoot and root dry matter and total P uptake were determined. Soil samples were taken before and after each of the 4 plant growth cycles and analyzed using a modified Hedley et al. (1982) soil P fractionation methodology. Labile-Pi, NaOH-Pi, HCI-Pi, extractable-Po, and residual -P were determined. Applied P increased labile-Pi, NaOH-Pi and HCI-Pi. Statistical changes were not observed in extractable organic P and residual-P due to P application. The NaOH-Pi and HCI-Pi seemed to act as a temporary pool of applied P. The possible participation of residual-P in replenishment of labile-P and NaOH-Pi was observed. The amount of plant P untake was closely related to the initial amount of labile-Pi and was higher in coffee than in forest and sugar cane soils. The labile-P was depleted by plant uptake. Rapid changes in reversibly available soil P forms (NaOH-Pi and HCI-Pi) were observed during the experiment. Our results suggest the occurrence of very rapid and dynamic changes between available and unavailable soil P forms in response to fertilizer application and plant uptake, supporting the idea of a continuum among the

Load and inflation pressure effects on soil compaction of forwarder tires

Science.gov (United States)

Tim McDonald; Tom Way; Bjorn Lofgren; Fernando Seixas; Mats Landstrom

1996-01-01

A standard forwarder tire (600/55-26.5) was tested to determine its range of soil compaction with various inflation pressures and dynamic loads. Past research has shown that compaction of heavier equipment can be somewhat mitigated by operating with lower inflation pressures. Results indicated a significant effect of both load and inflation pressure on bulk density,...

Lead, zinc and pHconcentrationsof Enyigba soils in Abakaliki Local ...

African Journals Online (AJOL)

STORAGESEVER

2008-07-18

Jul 18, 2008 ... Lead is relatively unavailable to plants when the soil pH is above 6.5, while availability of zinc ... zinc, in a soil is available for uptake by plants or move- ment down the soil profile depends on a range of .... incineration as manure including the natural occurrence of rock or ore bodies with high levels of trace ...

Increased P diffusion as an explanation of increased P availability in flooded rice soils

International Nuclear Information System (INIS)

Turner, F.T.; Gilliam, J.W.

1976-01-01

Phosphorus supply factors (capacity, kinetic, intensity, and diffusivity) and plant growth were the approaches used to assess P supply of flooded rice soils. Increases in the capacity, intensity and kinetic factors, as measured by E-value, solution P concentration, and soil P release rate to a distilled water 'sink' respectively, were unpronounced and infrequent upon water-saturation of ten soils. However, increases in the diffusivity factor, as measured by 32 P diffusion coefficients, were at least ten-fold as soil moisture increased. The greatest increases in P diffusion occurred as soil moisture increased beyond one-third bar. Using a P-fertilized soil or P treated powdered cellulose as the P source and a minus P nutrient solution to nourish a split root system with water and nutrients, data were obtained which suggested that P uptake and rice shoot growth (indicators of P availability) increased with increasing moisture level. Phosphorus uptake and rice-shoot growth were greatest when the soil or P treated cellulose were water-saturated. These data indicate that increased soil P availability upon flooding can be attributed to an increase in the diffusivity factor

Loading test of pile affected by soil layer deformation; Jiban henkei no eikyo wo ukeru kui no saika jikken

Energy Technology Data Exchange (ETDEWEB)

Kakurai, M.; Tsuchiya, T. [Takenaka Corp., Osaka (Japan)

1997-10-10

Large soil tank developed for shearing experiments is used to study the horizontal movement of piles in earthquakes. The system comprises a soil filled (8m deep) tank, pile head loading jig, and 6 actuators. The soil tank is fabricated of 40 layers of 20cm-high iron frames of inner dimensions 2.5mtimes2.5m, and it is filled with soil that is to simulate the ground. The frames are divided into 4 groups each containing 10 frames, and the frames in each group are coupled with each other, so that all the frames in one group will move horizontally when the topmost frame in the group is moved horizontally. An actuator, which travels horizontally ganging with a computer, is mounted on the top frame in each group, and this setup enables the arbitrary simulation of ground deformation in the horizontal direction in an earthquake. The pile head loading jig, driven by 2 actuators, can keep restraining the pile head from rotation while applying load or deforming force to the pile head as desired in the vertical and horizontal direction. Experiments conducted using this system involve the force imposed on a pile in the soil tank by ground deformation and the resultant pile behavior including breakdown. 9 figs.

Inorganic phosphorus fractionation and its translocation dynamics in a low-P soil

International Nuclear Information System (INIS)

Yang, J.C.; Wang, Z.G.; Zhou, J.; Jiang, H.M.; Zhang, J.F.; Pan, P.; Han, Z.; Lu, C.; Li, L.L.; Ge, C.L.

2012-01-01

The translocation of different inorganic phosphorus (Pi) forms in a low-P soil (Langfang experimental station, Hebei province, China) over time was investigated using P fractionation extraction and a 32 P tracer technique. The L-value and P availability of the soil was assessed using 5 different maize genotype (Zea mays L.) cultivars. The results showed that the different Pi fractions in the soil increased in the order of H 2 SO 4 -extractable P (Ca 10 –P) > Na 3 C 6 H 5 O 7 –Na 2 S 2 O 4 -extractable P (O–P) > NH 4 Ac-extractable P (Ca 8 –P) > NaHCO 3 -extractable P (Ca 2 –P), NH 4 F-extractable P (Al–P), NaOH–Na 2 CO 3 -extractable P (Fe–P), and the content of plant-unavailable P (Ca 10 –P + O–P) was high, up to 79.1%, which might be an important reason for P deficiency in this low-P soil. The 32 P tracer results showed that after the addition of 32 P-Pi to the soil with no P fertilizer applied for 25 d, 29.0% of 32 P was quickly transformed into Ca 2 –P (rapidly available P), and 66.1% of 32 P was transformed into Al–P, Fe–P and Ca 8 –P (slowly available P). Only 5.0% of 32 P was transformed into O–P and Ca 10 –P (plant-unavailable P). Moreover, in the soil with P fertilizer applied, 32 P transformation into Ca 2 –P increased, and the transformation into Ca 8 –P + Fe–P + AL–P and O–P, Ca 10 –P significantly decreased compared to the soil with no P fertilizer applied (p 32 P tracer. ► L-value and P availability assessed using 5 maize genotype. ► Observed higher rate of P transformation to unavailable P in deficient soil than in sufficient. ► Different genotypes had different soil P-use efficiency and low-P tolerance mechanisms.

Performance of Damaged Soil-Concrete Wraparound Dam Sections under Dynamic Loading

Energy Technology Data Exchange (ETDEWEB)

Kanarska, Y; Lomov, I; Glascoe, L; Morris, J; Antoun, T; Hall, R; Woodson, S; Fortune, J; Hynes, M E

2009-09-28

Predicting seismic or shock loading damage of the soil-concrete interface where an embankment wraparound dam provides support to the end monoliths in a concrete gravity dam is an inherently challenging three-dimensional coupled problem. We wish to predict formation and growth of a crack between the soil and concrete with a sustained flow of water. Further, we seek to better understand all critical phenomenology of this type of problem such as the potential mitigating and stabilizing role of upstream and downstream filter zone and shell materials. This collaborative research effort will ultimately determine whether advances in computational platforms, constitutive soil models (advances in representing particulates, tension, flow, and hydraulic erosion), and physical testing (advances in centrifuge and flume testing) can be applied successfully to solve this complex problem. Our focus is (1) to develop and validate high fidelity numerical models to investigate crack formation, soil erosion, transport of materials, and stability as part of the erosion process, and deposition within interface cracks; and (2) to investigate the performance of the filter zone materials if an extreme loading event such as an earthquake or shock damages the wraparound section. Our numerical tools include both continuum and discrete approaches. The continuum approach is based on the drift-flux multiphase model where a fluid and a solid are represented as interpenetrating continua and can account for turbulent flow characteristics, particle lift forces due to shear flow, particle collisions, and gravity settling. The discrete particle approach is also applied and is useful when deriving constitutive laws and parameterizations of soil behavior. Different experimental validation studies are under consideration for model validation and calibration. Several case studies for different crack sizes and orientations, particle sizes and environmental hydraulic conditions may be required to confirm

The status of phosphorus in Thai soils and P evaluation using EDTA-NaF extraction method

Directory of Open Access Journals (Sweden)

Toru Matoh

2003-07-01

Full Text Available Although the available P extracted by Bray II method in tropical soil is low, most of tropical plants can grow well. The objective of this study was to study P status and to evaluate the available P extracted by EDTA-NaF method. Top soil and sub soil of 10 dominant soil series in Thailand were analyzed for some chemical properties and characterization of the forms of phosphorus using EDTA-NaF extraction and successive phosphorus extraction by the modified Sekiya method. The soil total P concentration was 38-1137 mg P2O5 kg-1. The available Bray II-P was very low to high (1-76 mg P2O5 kg-1, and it approximated 0.17-12% of the total P. Iron and aluminum phosphates were the main fraction of inorganic P in acid soil, whereas Ca phosphates were in calcareous soils. Organic P content accounted for 33-67% and most of them were bound with Fe and Al in acid soils and Ca in calcareous soils. P extracted by EDTA-NaF reagent was obviously larger than that of Bray II reagent. The EDTA-NaF extracted P [high molecular weight organic P (HMWP+ inorganic P (EDTA ext Pi] was 7-46% and 1-6% of total P in acid soils and calcareous soils respectively. The EDTA ext Pi tended to be larger than HMWP except in Tk soil. The total amount of extracted P correlated well with Al-Pi and Fe-Pi which were the main fraction of inorganic P. It also correlated with HMWP, but HMWP did not correlate with organic P determine by ignition method and Ca-Po, Fe-Po and Al-Po. The EDTA-NaF method may be suitable for P evaluation in the soils which have high amounts of Fe-Pi, Al -Pi and organic P widely distributed in Thailand.

Effect of N and P addition on soil organic C potential mineralization in forest soils in South China

Institute of Scientific and Technical Information of China (English)

OUYANG Xuejun; ZHOU Guoyi; HUANG Zhongliang; ZHOU Cunyu; LI Jiong; SHI Junhui; ZHANG Deqiang

2008-01-01

Atmospheric nitrogen deposition is at a high level in some forests of South China. The effects of addition of exogenous N and P on soil organic carbon mineralization were studied to address: (1) if the atmospheric N deposition promotes soil C storage through decreasing mineralization; (2) if the soil available P is a limitation to organic carbon mineralization. Soils (0-10 cm) was sampled from monsoon evergreen broad-leaved forest (MEBF), coniferous and broad-leaved mixed forest (CBMF), and Pinus massoniana forest (PMF) in Dinghushan Biosphere Reserve (located in Gnangdong Province, China). The soils were incubated at 25℃ for 45 weeks, with addition of N (NH4NO3 solution) or P (KH2PO4 solution). CO2-C emission and the inorganic N (NH4+-N and NO3--N) of the soils were determined during the incubation. The results showed that CO2-C emission decreased with the N addition. The addition of P led to a short-term sharp increase in CO2 emission after P application, and the responses of CO2-C evolution to P addition in the later period of incubation related to forest types. Strong P inhibition to CO2 emission occurred in both PMF and CBMF soils in the later incubation. The two-pool kinetic model was fitted well to the data for C turnover in this experiment. The model analysis demonstrated that the addition of N and P changed the distribution of soil organic C between the labile and recalcitrant pool, as well as their mineralization rates. In our experiment, soil pH can not completely explain the negative effect of N addition on CO2-C emission. The changes of soil inorganic N during incubation seemed to support the hypothesis that the polymerization of added nitrogen with soil organic compound by abiotic reactions during incubation made the added nitrogen retard the soil organic carbon mineralization. We conclude that atmospheric N deposition contributes to soil C accretion in the three subtropical forest ecosystems, however, the shortage of soil available P in CBMF and

Behavior of a strip footing on reinforced soil subjected to inclined load

Directory of Open Access Journals (Sweden)

Abbas Jawdat

2018-01-01

Full Text Available This study investigates the behavior of a strip footing under inclined load on reinforced sandy soil by using experimental model. The effect of the load inclination angle (α, number of geogrid layers (N and the relative density (RD on the bearing capacity, settlement and horizontal displacement were studied. The results showed that by increasing the number of reinforcement layers (N, the bearing capacity increased, but there is an optimum value (N=4-5 depending on relative density of supporting soil. Also the settlement and horizontal displacement of footing decreasing with increase number of reinforcement layers.

Soil pH mapping with an on-the-go sensor.

Science.gov (United States)

Schirrmann, Michael; Gebbers, Robin; Kramer, Eckart; Seidel, Jan

2011-01-01

Soil pH is a key parameter for crop productivity, therefore, its spatial variation should be adequately addressed to improve precision management decisions. Recently, the Veris pH Manager™, a sensor for high-resolution mapping of soil pH at the field scale, has been made commercially available in the US. While driving over the field, soil pH is measured on-the-go directly within the soil by ion selective antimony electrodes. The aim of this study was to evaluate the Veris pH Manager™ under farming conditions in Germany. Sensor readings were compared with data obtained by standard protocols of soil pH assessment. Experiments took place under different scenarios: (a) controlled tests in the lab, (b) semicontrolled test on transects in a stop-and-go mode, and (c) tests under practical conditions in the field with the sensor working in its typical on-the-go mode. Accuracy issues, problems, options, and potential benefits of the Veris pH Manager™ were addressed. The tests demonstrated a high degree of linearity between standard laboratory values and sensor readings. Under practical conditions in the field (scenario c), the measure of fit (r(2)) for the regression between the on-the-go measurements and the reference data was 0.71, 0.63, and 0.84, respectively. Field-specific calibration was necessary to reduce systematic errors. Accuracy of the on-the-go maps was considerably higher compared with the pH maps obtained by following the standard protocols, and the error in calculating lime requirements was reduced by about one half. However, the system showed some weaknesses due to blockage by residual straw and weed roots. If these problems were solved, the on-the-go sensor investigated here could be an efficient alternative to standard sampling protocols as a basis for liming in Germany.

Simplified Probabilistic Analysis of Settlement of Cyclically Loaded Soil Stratum by Point Estimate Method

Science.gov (United States)

Przewłócki, Jarosław; Górski, Jarosław; Świdziński, Waldemar

2016-12-01

The paper deals with the probabilistic analysis of the settlement of a non-cohesive soil layer subjected to cyclic loading. Originally, the settlement assessment is based on a deterministic compaction model, which requires integration of a set of differential equations. However, with the use of the Bessel functions, the settlement of a soil stratum can be calculated by a simplified algorithm. The compaction model parameters were determined for soil samples taken from subsoil near the Izmit Bay, Turkey. The computations were performed for various sets of random variables. The point estimate method was applied, and the results were verified by the Monte Carlo method. The outcome leads to a conclusion that can be useful in the prediction of soil settlement under seismic loading.

Basic study on promotion of thawing frozen soil by shock loading

Directory of Open Access Journals (Sweden)

Toshiaki WATANABE

2008-06-01

Full Text Available The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. In the case of small processing area such as road repairing, frozen soil is thawed by using the heat of gas burner and/or the electric heater. It is not a suitable plan to apply these heating methods to agriculture, from the point of view enormous amount of processing area. Thawing technique for frozen soil is effective against the cold regions, for example, Russia, Norway, and Sweden, etc. At first, we carried out experiments using a detonating fuse and ice block. The propagation process of shock wave into the ice block was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave. We could get a result that existence of water layer serves an important role in promotion of thawing by the shock loading to the frozen soil.

Regional analysis of groundwater phosphate concentrations under acidic sandy soils: Edaphic factors and water table strongly mediate the soil P-groundwater P relation.

Science.gov (United States)

Mabilde, Lisa; De Neve, Stefaan; Sleutel, Steven

2017-12-01

Historic long-term P application to sandy soils in NW-Europe has resulted in abundant sorption, saturation and eventually leaching of P from soil to the groundwater. Although many studies recognize the control of site-specific factors like soil texture and phosphate saturation degree (PSD), the regional-scaled relevance of effects exerted by single factors controlling P leaching is unclear. Very large observational datasets of soil and groundwater P content are furthermore required to reveal indirect controls of soil traits through mediating soil variables. We explored co-variation of phreatic groundwater orthophosphate (o-P) concentration and soil factors in sandy soils in Flanders, Belgium. Correlation analyses were complemented with an exploratory model derived using 'path analysis'. Data of oxalate-extractable Al, Fe, P and pH KCl , phosphate sorption capacity (PSC) and PSD in three depth layers (0-30, 30-60, 60-90 cm), topsoil SOC, % clay and groundwater depth (fluctuation) were interpolated to predict soil properties on exact locations of a very extensive net of groundwater monitoring wells. The mean PSD was only poorly correlated to groundwater o-P concentration, indicating the overriding control of other factors in the transport of P to the groundwater. A significant (P soil pH and groundwater table depth than by PSD indicates the likely oversimplification of the latter index to measure the long-term potential risk of P leaching. Accounting for controls on leaching not included in PSD via an alternative index, however, seems problematic as in Flanders for example groundwater o-P turned out to be higher in finer textured soils or soils with higher pedogenic Fe content, probably because of their lower pedogenic Al content and higher soil pH. Path analysis of extensive soil and groundwater datasets seems a viable way to identify prime local determinants of soil P leaching and could be further on used for 'ground-truthing' more complex P-migration simulation

Phosphorus (32 P) adsorption kinetics and equilibrium in soils of Pernambuco State, Brazil

International Nuclear Information System (INIS)

Machado, Lucivaldo Celestino.

1996-01-01

The objective of this work was to determine the relationship between the P fixing capacity of various soils and their hydrous oxide content. The relationship with other soil variables was also analysed. This fixing capacity was evaluated through adsorption isotherms and isotopic exchange kinetics of 32 P in samples with high and low P concentrations. Samples from 11 soils, cultivated with sugar-cane, representing five soil classes (non-humic gley, red-yellow Podzolic, red-yellow latossolic, distrofic quartzitic sand and distrofic organic). The soils were sampled in the southern humid coastal region of the state of Pernambuco. Soil were sampled immediately after harvest of the plant-cane. The results of the basic soil chemical analysis showed that all soils had pH values in the acid range,varying from 3.87 to 6.31. Total organic C was always less than 12 mg C/g, except for the organic soil that had 75 mg C/g soil. In soils with R 1 /R 0 between 0,01 and 0,1 the proportion of resin P oscillated between 10 and 20 of the increase in total inorganic P, while in those with R 1 /R 0 > 0,1 the proportion was larger than 20% with one exception. (author). 44 refs., 9 figs., 6 tabs

Availability of native and fertilizer P in Brazilian soils

International Nuclear Information System (INIS)

Scivittaro, W.B.; Muraoka, T.; Boaretto, A.E.; Brasil, E.C.

2002-01-01

Inorganic forms of phosphorus were determined in two Red-Yellow Latosols, which were incubated with P fertilizers for a month, after equilibration with 32 P for 60 hours. The methods used were soil P fractionation combined with the 32 P isotopic dilution technique. The fertilizers applied were: H 3 PO 4 , 10-30-0 suspension, MAP and triple superphosphate, at the rate of 92 mg P kg -1 of soil. In both soils, the isotopically exchangeable inorganic phosphorus fractions decreased in the following order: water soluble P > Al bound P > Fe bound P > calcium bound P > occluded-P. The water- soluble and Al bound P were the main source of available P for the newly fertilized soil. The Fe bound phosphate was also an important source of available P in both soils when fertilizer was not applied. The soil P fixing capacity affected the availability of native and added phosphorus. (author)

Soil solution interactions may limit Pb remediation using P ...

Science.gov (United States)

Lead (Pb) contaminated soils are a potential exposure hazard to the public. Amending soils with phosphorus (P) may reduce Pb soil hazards. Soil from Cleveland, OH containing 726 ± 14 mg Pb kg-1 was amended in a laboratory study with bone meal and triple super phosphate (TSP) at 5:1 P:Pb molar ratios. Soil was acidified, neturalized and re-acidified to encourage Pb phosphate formation. PRSTM-probes were used to evaluate changes in soil solution chemistry. Soil acidification did not decrease in vitro bioaccessible (IVBA) Pb using either a pH 1.5, 0.4 M glycine solution or a pH 2.5 solution with organic acids. PRSTM-probe data found soluble Pb increased 10-fold in acidic conditions compared to circumnetural pH conditions. In acidic conditions (p = 3-4), TSP treated soils increased detected P 10-fold over untreated soils. Bone meal application did not increase PRSTM-probe detected P, indicating there may have been insufficient P to react with Pb. X-ray absorption spectroscopy suggested a 10% increase in pyromorphite formation for the TSP treated soil only. Treatments increased soil electrical conductivity above 16 mS cm-1, potentially causing a new salinity hazard. This study used a novel approach by combining the human ingestion endpoint, PRSTM-probes, and X-ray absorption spectroscopy to evaluate treatment efficacy. PRSTM-probe data indicated potentially excess Ca relative to P across incubation steps that could have competed with Pb for soluble P. Mor

Biochar contribution to soil pH buffer capacity

Science.gov (United States)

Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

2014-05-01

Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type

Fractionation of applied 32P labeled TSP in calcareous soils

International Nuclear Information System (INIS)

Asfary, A.F.; Al-Merey, R.; Al-Hameish, M.

2005-01-01

Calcareous dark brown red soil (calcixerollic xerochrept) from northern Syria was used in a pot experiment to study the fate of triple super phosphate fertilizer (TSP) with and without a crop (Local durum wheat (Triticum turgidum L. group durum (Desf)) c v. Bohouth). The soil received 17μg P/g soil of 32 P labeled TSP, and samples were collected from soils and plants at successive dates. Soil inorganic P was ≅94% of total soil P, with only 50-80% being soluble. Calcium phosphate compounds were the dominant fraction (≤68%) of the soluble inorganic soil P followed by occluded iron phosphate (≤48%) and all other fractions were ≤9%. Isotopic measurements showed that ≅ 50% of fertilizer P was nonexchangeable within 2 days, and TSP values in each fraction of soil inorganic P fluctuated in relatively similar proportions to the concentrations of fractions in soil. Available P (soil and TSP) in cropped soil was more than that in the uncropped soil, and plants had no effect on the distribution of P from fertilizer amongst the different P fractions. (author)

STRAIN-STRESS DISTRIBUTION OF “HOMOGENEOUS” SOIL MASS DURING THE LOAD TRANSMITTED THROUGH THE LIMITED AREA IN THE PLAN, APPLIED INSIDE THE ELASTIC HOMOGENEOUS SOIL MASS

Directory of Open Access Journals (Sweden)

BOLSHAKOV V. I.

2017-03-01

Full Text Available Summary. Based on the current understanding of the piles work in clayey soils; that is forming during driving process a compacted core (compacted platform in the pile tip plane and transferring the load from the pile (from the piling foundation not through the pile tip but through the pressed core (compacted platform, the stress in the soil mass by the load applied inside the elastic half-space is determined with the change in the calculated scheme of load transferring to the “homogeneous” soil mass.

Effect of plastic soil on a retaining wall subjected to surcharge loading

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Al-Juari Khawla

2016-01-01

Full Text Available The seasonal variation and climatic changes play a significant role that affects the stresses exerted on a retaining wall, and the state of stresses in the soil mass behind the wall especially for highly expansive soil. These stresses resulted in the wall moving either away or towards the soil. In this study, a laboratory physical model of the retaining wall formed of a box having (950×900×600 mm dimensions with one side representing the wall being developed. After the soil being laid out in the box in specified layers, specified conditions of saturation and normal stresses were applied. The wall is allowed to move horizontally in several distances (0.1, 0.2, 0.3, 0.6, 0.8, 1.0 , 2.0, 3.0 and 4.0 mm, and the stresses being measured, then the vertical loading was released. The main measured variables during the tests are; the active and passive earth pressures, vertical movement of the soil, total suction and time. Results showed that the lateral earth pressure along the depth of the wall largely decreased when wall moved away from the soil. Total suction was slightly affected during wall’s movement. At unloading stage, the lateral earth pressure decreased at the upper half of wall height, but increased at the other wall part. Total suction was increased at all depths during this stage.

Influence of pH on pesticide sorption by soil containing wheat residue-derived char

International Nuclear Information System (INIS)

Sheng Guangyao; Yang Yaning; Huang Minsheng; Yang Kai

2005-01-01

Field burning of crop residues incorporates resulting chars into soil and may thus influence the environmental fate of pesticides in the soil. This study evaluated the influence of pH on the sorption of diuron, bromoxynil, and ametryne by a soil in the presence and absence of a wheat residue-derived char. The sorption was measured at pHs ∼3.0 and ∼7.0. Wheat char was found to be a highly effective sorbent for the pesticides, and its presence (1% by weight) in soil contributed >70% to the pesticide sorption (with one exception). The sorption of diuron was not influenced by pH, due to its electroneutrality. Bromoxynil becomes dissociated at high pHs to form anionic species. Its sorption by soil and wheat char was lower at pH ∼7.0 than at pH ∼3.0, probably due to reduced partition of the anionic species of bromoxynil into soil organic matter and its weak interaction with the carbon surface of the char. Ametryne in its molecular form at pH ∼7.0 was sorbed by char-amended soil via partitioning into soil organic matter and interaction with the carbon surface of the char. Protonated ametryne at pH ∼3.0 was substantially sorbed by soil primarily via electrostatic forces. Sorption of protonated ametryne by wheat char was also significant, likely due not only to the interaction with the carbon surface but also to interactions with hydrated silica and surface functional groups of the char. Sorption of ametryne by char-amended soil at pH ∼3.0 was thus influenced by both the soil and the char. Environmental conditions may thus significantly influence the sorption and behavior of pesticides in agricultural soils containing crop residue-derived chars. - Wheat char was effective for adsorption of pesticides in soil, with efficacy varying with pH and particular pesticides

Influence of pH on pesticide sorption by soil containing wheat residue-derived char

Energy Technology Data Exchange (ETDEWEB)

Sheng Guangyao [Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701 (United States)]. E-mail: gsheng@uark.edu; Yang Yaning [Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72701 (United States); Huang Minsheng [Department of Environmental Science and Technology, East China Normal University, Shanghai 200062 (China); Yang Kai [Department of Environmental Science and Technology, East China Normal University, Shanghai 200062 (China)

2005-04-01

Field burning of crop residues incorporates resulting chars into soil and may thus influence the environmental fate of pesticides in the soil. This study evaluated the influence of pH on the sorption of diuron, bromoxynil, and ametryne by a soil in the presence and absence of a wheat residue-derived char. The sorption was measured at pHs {approx}3.0 and {approx}7.0. Wheat char was found to be a highly effective sorbent for the pesticides, and its presence (1% by weight) in soil contributed >70% to the pesticide sorption (with one exception). The sorption of diuron was not influenced by pH, due to its electroneutrality. Bromoxynil becomes dissociated at high pHs to form anionic species. Its sorption by soil and wheat char was lower at pH {approx}7.0 than at pH {approx}3.0, probably due to reduced partition of the anionic species of bromoxynil into soil organic matter and its weak interaction with the carbon surface of the char. Ametryne in its molecular form at pH {approx}7.0 was sorbed by char-amended soil via partitioning into soil organic matter and interaction with the carbon surface of the char. Protonated ametryne at pH {approx}3.0 was substantially sorbed by soil primarily via electrostatic forces. Sorption of protonated ametryne by wheat char was also significant, likely due not only to the interaction with the carbon surface but also to interactions with hydrated silica and surface functional groups of the char. Sorption of ametryne by char-amended soil at pH {approx}3.0 was thus influenced by both the soil and the char. Environmental conditions may thus significantly influence the sorption and behavior of pesticides in agricultural soils containing crop residue-derived chars. - Wheat char was effective for adsorption of pesticides in soil, with efficacy varying with pH and particular pesticides.

A model to explain high values of pH in an alkali sodic soil Modelo para explicar valores elevados de pH em um solo sódico alcalino

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José Guerrero-Alves

2002-12-01

Full Text Available For alkali sodic soils (pH>8.5, the "hydrolysis of exchangeable sodium" has been used as a possible explanation for the alkalinity production and rise in pH of these soils. As an alternative to this hypothesis, a model was developed to simulate and to explain that the alkalinity production and rise in pH is possible in a soil that accumulates alkaline sodium salts and CaCO3. Several simulations were performed by using different combinations of CO2 partial pressures (P, presence or absence of MgCO3, along with experimental values of exchangeable sodium percentage (ESP and ion concentrations in saturation extracts from an alkali sodic soil (named Pantanal. A hypothetical system with similar conditions to the Pantanal soil but with a Gapon selectivity coefficient (KG of 0.01475 (mmol L-1-1/2 was also considered. Good agreement was obtained between experimental and predicted values for pH and ion concentrations in the soil solution when the model (without MgCO3 was applied to the Pantanal soil. However, KG values calculated for the Pantanal soil were generally higher than 0.01475 (mmol L-1-1/2. Moreover, high pH values and elevated ionic strength were obtained when a KG of 0.01475 (mmol L-1-1/2 was used at high ESP (similar to those found in the Pantanal soil. KG values obtained for the Pantanal soil and the results obtained in the simulation of the hypothetical system are suggesting that a value higher than 0.01475 (mmol L-1-1/2 should be used to adequately simulate the behavior of the Pantanal soil at low ionic strength and high ESP values.Em solos alcalino sódicos (pH>8,5, a "hidrólise de sódio trocável" tem sido usada como uma possível explicação para a produção de álcali e elevação do pH nestes solos. Como uma alternativa a essa hipótese, um modelo foi desenvolvido para simular e explicar que a produção de álcali e elevação do pH é possível num solo que acumula sais alcalinos de sódio e CaCO3. Várias simulações foram

[Mapping Critical Loads of Heavy Metals for Soil Based on Different Environmental Effects].

Science.gov (United States)

Shi, Ya-xing; Wu, Shao-hua; Zhou, Sheng-lu; Wang, Chun-hui; Chen, Hao

2015-12-01

China's rapid development of industrialization and urbanization causes the growing problem of heavy metal pollution of soil, threatening environment and human health. Therefore, prevention and management of heavy metal pollution become particularly important. Critical loads of heavy metals are an important management tool that can be utilized to prevent the occurrence of heavy metal pollution. Our study was based on three cases: status balance, water environmental effects and health risks. We used the steady-state mass balance equation to calculate the critical loads of Cd, Cu, Pb, Zn at different effect levels and analyze the values and spatial variation of critical loads. In addition, we used the annual input fluxes of heavy metals of the agro-ecosystem in the Yangtze River delta and China to estimate the proportion of area with exceedance of critical loads. The results demonstrated that the critical load value of Cd was the minimum, and the values of Cu and Zn were lager. There were spatial differences among the critical loads of four elements in the study area, lower critical loads areas mainly occurred in woodland and high value areas distributed in the east and southwest of the study area, while median values and the medium high areas mainly occurred in farmland. Comparing the input fluxes of heavy metals, we found that Pb and Zn in more than 90% of the area exceeded the critical loads under different environmental effects in the study area. The critical load exceedance of Cd mainly occurred under the status balance and the water environmental effect, while Cu under the status balance and water environmental effect with a higher proportion of exceeded areas. Critical loads of heavy metals at different effect levels in this study could serve as a reference from effective control of the emissions of heavy metals and to prevent the occurrence of heavy metal pollution.

A conceptual framework: Redefining forest soil's critical acid loads under a changing climate

International Nuclear Information System (INIS)

McNulty, Steven G.; Boggs, Johnny L.

2010-01-01

Federal agencies of several nations have or are currently developing guidelines for critical forest soil acid loads. These guidelines are used to establish regulations designed to maintain atmospheric acid inputs below levels shown to damage forests and streams. Traditionally, when the critical soil acid load exceeds the amount of acid that the ecosystem can absorb, it is believed to potentially impair forest health. The excess over the critical soil acid load is termed the exceedance, and the larger the exceedance, the greater the risk of ecosystem damage. This definition of critical soil acid load applies to exposure of the soil to a single, long-term pollutant (i.e., acidic deposition). However, ecosystems can be simultaneously under multiple ecosystem stresses and a single critical soil acid load level may not accurately reflect ecosystem health risk when subjected to multiple, episodic environmental stress. For example, the Appalachian Mountains of western North Carolina receive some of the highest rates of acidic deposition in the eastern United States, but these levels are considered to be below the critical acid load (CAL) that would cause forest damage. However, the area experienced a moderate three-year drought from 1999 to 2002, and in 2001 red spruce (Picea rubens Sarg.) trees in the area began to die in large numbers. The initial survey indicated that the affected trees were killed by the southern pine beetle (Dendroctonus frontalis Zimm.). This insect is not normally successful at colonizing these tree species because the trees produce large amounts of oleoresin that exclude the boring beetles. Subsequent investigations revealed that long-term acid deposition may have altered red spruce forest structure and function. There is some evidence that elevated acid deposition (particularly nitrogen) reduced tree water uptake potential, oleoresin production, and caused the trees to become more susceptible to insect colonization during the drought period

Root growth of Lotus corniculatus interacts with P distribution in young sandy soil

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B. Felderer

2013-03-01

Full Text Available Large areas of land are restored with unweathered soil substrates following mining activities in eastern Germany and elsewhere. In the initial stages of colonization of such land by vegetation, plant roots may become key agents in generating soil formation patterns by introducing gradients in chemical and physical soil properties. On the other hand, such patterns may be influenced by root growth responses to pre-existing substrate heterogeneities. In particular, the roots of many plants were found to preferentially proliferate into nutrient-rich patches. Phosphorus (P is of primary interest in this respect because its availability is often low in unweathered soils, limiting especially the growth of leguminous plants. However, leguminous plants occur frequently among the pioneer plant species on such soils, as they only depend on atmospheric nitrogen (N fixation as N source. In this study we investigated the relationship between root growth allocation of the legume Lotus corniculatus and soil P distribution on recently restored land. As test sites, the experimental Chicken Creek Catchment (CCC in eastern Germany and a nearby experimental site (ES with the same soil substrate were used. We established two experiments with constructed heterogeneity, one in the field on the experimental site and the other in a climate chamber. In addition, we conducted high-density samplings on undisturbed soil plots colonized by L. corniculatus on the ES and on the CCC. In the field experiment, we installed cylindrical ingrowth soil cores (4.5 × 10 cm with and without P fertilization around single two-month-old L. corniculatus plants. Roots showed preferential growth into the P-fertilized ingrowth-cores. Preferential root allocation was also found in the climate chamber experiment, where single L. corniculatus plants were grown in containers filled with ES soil and where a lateral portion of the containers was additionally supplied with a range of different P

Comparative study of P uptake and utilization from P fertilizers by Chilean wheat genotypes in volcanic ash soils

International Nuclear Information System (INIS)

Pino, I.; Parada, A.M.; Zapata, F.; Navia, M.; Luzio, W.

2002-01-01

The intensification of the agricultural production in Southern Chile demand the application of P fertilizers to volcanic ash soils for optimum plant growth and crop yields. Due to the high P sorption capacities of these soils, high amounts of water-soluble phosphatic fertilizers need to be applied. Therefore, the direct application of locally available Bahia Inglesa phosphate rock has been utilized to supply P to crops in these acid soils. Phosphate rock is a very efficient P input for crops with long growth cycles or crop rotations nevertheless water-soluble P fertilizers must still be applied to crops of short growth cycle. Combined with these strategic P inputs, the use of acid-tolerant and P-efficient genotypes can further contribute to agricultural sustainability. Greenhouse studies were undertaken to explore and identify genotypic variations in P efficiency of wheat grown in Andisols of Southern Chile. 32 P isotopic techniques were utilized to measure the uptake of P from triple superphosphate, a water-soluble P fertilizer and the locally available Bahia Inglesa phosphate rock. Substantial genotypic variations in P use efficiency were found among the Chilean wheat genotypes tested. The utilization of the 32 P isotopic techniques enabled to quantify the P taken up from the P fertilizer and the assessment of differences among the genotypes. Significant genotypic differences were obtained in the P uptake from the local phosphate rock Bahia Inglesa. Much higher applications of phosphate rock were required in Santa Barbara soil series (Andisol) due to its high P retention. A sustainable strategy for agricultural production in the Andisols of Chile would therefore, be the combined utilization of those efficient wheat genotypes and the local phosphate rock Bahia Inglesa. As P efficiency is a multi-faceted trait, which interacts with a range of environmental factors, further field-testing and validation is required accompanied by in depth studies to assess the

Biodegradation of Aged Residues of Atrazine and Alachlor in a Mix-Load Site Soil by Fungal Enzymes

OpenAIRE

Chirnside, Anastasia E. M.; Ritter, William F.; Radosevich, Mark

2011-01-01

Soils from bulk pesticide mixing and loading (mix-load) sites are often contaminated with a complex mixture of pesticides, herbicides, and other organic compounds used in pesticide formulations that limits the success of remediation efforts. Therefore, there is a need to find remediation strategies that can successfully clean up these mix-load site soils. This paper examined the degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT) and alachlor (2-chloro- 2  , 6  -...

Phytoremediation of high phosphorus soil by annual ryegrass and common bermudagrass harvest

Science.gov (United States)

Removal of soil phosphorus (P) in crop harvest is a remediation option for soils high in P. This four-year field-plot study determined P uptake by annual ryegrass (ARG, Lolium multiflorum Lam.) and common bermudagrass (CB, Cynodon dactylon (L.) Pers.) from Ruston soil (fine-loamy, siliceous, thermic...

Steady-state critical loads of acidity for forest soils in the Georgia Basin, British Columbia

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Shaun A. WATMOUGH

2010-08-01

Full Text Available There has been growing interest in acid rain research in western Canada where sulphur (S and nitrogen (N emissions are expected to increase during the next two decades. One region of concern is southern British Columbia, specifically the Georgia Basin, where emissions are expected to increase owing to the expansion of industry and urban centres (Vancouver and Victoria. In the current study, weathering rates and critical loads of acidity (S and N for forest soils were estimated at nineteen sites located within the Georgia Basin. A base cation to aluminium ratio of 10 was selected as the critical chemical criterion associated with ecosystem damage. The majority of the sites (58% had low base cation weathering rates (≤50 meq m–2 y–1 based on the PROFILE model. Accordingly, mean critical load for the study sites, estimated using the steady-state mass balance model, ranged between 129–168 meq m–2 y–1. Annual average total (wet and dry S and N deposition during the period 2005–2006 (estimated by the Community Multiscale Air Quality model, exceeded critical load at five–nine of the study sites (mean exceedance = 32–46 meq m–2 y–1. The high-elevation (>1000 m study sites had shallow, acid sensitive, soils with low weathering rates; however, critical loads were predominantly exceeded at sites close to Vancouver under higher modelled deposition loads. The extent of exceedance is similar to other industrial regions in western and eastern Canada.

Lower-Bound Calculations of the Bearing Capacity of Eccentrically Loaded Footings in Cohesionless Soil

DEFF Research Database (Denmark)

Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

2012-01-01

Lower-bound calculations based on the finite element method are used to determine the bearing capacity of a strip foundation subjected to a vertical, eccentric load on cohesionless soil with varying surcharges. The soil is assumed perfectly plastic following the Mohr-Coulomb failure criterion. Th...

Community structure and soil pH determine chemoautotrophic carbon dioxide fixation in drained paddy soils.

Science.gov (United States)

Long, Xi-En; Yao, Huaiying; Wang, Juan; Huang, Ying; Singh, Brajesh K; Zhu, Yong-Guan

2015-06-16

Previous studies suggested that microbial photosynthesis plays a potential role in paddy fields, but little is known about chemoautotrophic carbon fixers in drained paddy soils. We conducted a microcosm study using soil samples from five paddy fields to determine the environmental factors and quantify key functional microbial taxa involved in chemoautotrophic carbon fixation. We used stable isotope probing in combination with phospholipid fatty acid (PLFA) and molecular approaches. The amount of microbial (13)CO2 fixation was determined by quantification of (13)C-enriched fatty acid methyl esters and ranged from 21.28 to 72.48 ng of (13)C (g of dry soil)(-1), and the corresponding ratio (labeled PLFA-C:total PLFA-C) ranged from 0.06 to 0.49%. The amount of incorporationof (13)CO2 into PLFAs significantly increased with soil pH except at pH 7.8. PLFA and high-throughput sequencing results indicated a dominant role of Gram-negative bacteria or proteobacteria in (13)CO2 fixation. Correlation analysis indicated a significant association between microbial community structure and carbon fixation. We provide direct evidence of chemoautotrophic C fixation in soils with statistical evidence of microbial community structure regulation of inorganic carbon fixation in the paddy soil ecosystem.

Rhizosphere organic anions play a minor role in improving crop species’ ability to take up residual phosphorus (P in agricultural soils low in P availability

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Yanliang Wang

2016-11-01

Full Text Available Many arable lands have accumulated large reserves of residual phosphorus (P and a relatively large proportion of soil P is less available for uptake by plants. Root released organic anions are widely documented as a key physiological strategy to enhance P availability, while limited information has been generated on the contribution of rhizosphere organic anions to P utilization by crops grown in agricultural soils that are low in available P and high in extractable Ca, Al and Fe. We studied the role of rhizosphere organic anions in P uptake from residual P in four common crops Triticum aestivum, Avena sativa, Solanum tuberosum and Brassica napus in low- and high-P availability agricultural soils from long-term fertilization field trials in a mini-rhizotron experiment with four replications. Malate was generally the dominant organic anion. More rhizosphere citrate was detected in low P soils than in high P soil. Brassica napus showed 74-103% increase of malate in low P loam, compared with clay loam. Avena sativa had the greatest rhizosphere citrate concentration in all soils (5.3-15.2 mol g-1 root DW. Avena sativa also showed the highest level of root colonization by arbuscular mycorrhizal fungi (36% and 40%, the greatest root mass ratio (0.51 and 0.66 in the low-P clay loam and loam respectively, and the greatest total P uptake (5.92 mg P/mini-rhizotron in the low-P loam. Brassica napus had 15-44% more rhizosphere APase activity, ~0.1-0.4 units lower rhizosphere pH than other species, the greatest increase in rhizosphere water-soluble P in the low-P soils, and the greatest total P uptake in the low-P clay loam. Shoot P content was mainly explained by rhizosphere APase activity, water-soluble P and pH within low P soils across species. Within species, P uptake was mainly linked to rhizosphere water soluble P, APase and pH in low P soils. The effects of rhizosphere organic anions varied among species and they appeared to play minor roles in

Rhizosphere Organic Anions Play a Minor Role in Improving Crop Species' Ability to Take Up Residual Phosphorus (P) in Agricultural Soils Low in P Availability.

Science.gov (United States)

Wang, Yanliang; Krogstad, Tore; Clarke, Jihong L; Hallama, Moritz; Øgaard, Anne F; Eich-Greatorex, Susanne; Kandeler, Ellen; Clarke, Nicholas

2016-01-01

Many arable lands have accumulated large reserves of residual phosphorus (P) and a relatively large proportion of soil P is less available for uptake by plants. Root released organic anions are widely documented as a key physiological strategy to enhance P availability, while limited information has been generated on the contribution of rhizosphere organic anions to P utilization by crops grown in agricultural soils that are low in available P and high in extractable Ca, Al, and Fe. We studied the role of rhizosphere organic anions in P uptake from residual P in four common crops Triticum aestivum, Avena sativa, Solanum tuberosum , and Brassica napus in low- and high-P availability agricultural soils from long-term fertilization field trials in a mini-rhizotron experiment with four replications. Malate was generally the dominant organic anion. More rhizosphere citrate was detected in low P soils than in high P soil. B. napus showed 74-103% increase of malate in low P loam, compared with clay loam. A. sativa had the greatest rhizosphere citrate concentration in all soils (5.3-15.2 μmol g -1 root DW). A. sativa also showed the highest level of root colonization by arbuscular mycorrhizal fungi (AMF; 36 and 40%), the greatest root mass ratio (0.51 and 0.66) in the low-P clay loam and loam respectively, and the greatest total P uptake (5.92 mg P/mini-rhizotron) in the low-P loam. B. napus had 15-44% more rhizosphere acid phosphatase (APase) activity, ~0.1-0.4 units lower rhizosphere pH than other species, the greatest increase in rhizosphere water-soluble P in the low-P soils, and the greatest total P uptake in the low-P clay loam. Shoot P content was mainly explained by rhizosphere APase activity, water-soluble P and pH within low P soils across species. Within species, P uptake was mainly linked to rhizosphere water soluble P, APase, and pH in low P soils. The effects of rhizosphere organic anions varied among species and they appeared to play minor roles in

Soil compaction: Evaluation of stress transmission and resulting soil structure

DEFF Research Database (Denmark)

Naveed, Muhammad; Schjønning, Per; Keller, Thomas

strength. As soon as the applied load is lower than the aggregate strength, the mode of stress transmission is discrete as stresses were mainly transmitted through chain of aggregates. With increasing applied load soil aggregates start deforming that transformed heterogeneous soil into homogenous......, as a result stress transmission mode was shifted from discrete towards more like a continuum. Continuum-like stress transmission mode was better simulated with Boussinesq (1885) model based on theory of elasticity compared to discrete. The soil-pore structure was greatly affected by increasing applied...... and compaction-resulted soil structure at the same time. Stress transmission was quantified using both X-ray CT and Tactilus sensor mat, and soil-pore structure was quantified using X-ray CT. Our results imply that stress transmission through soil highly depends on the magnitude of applied load and aggregate...

Biogenic precipitation of manganese oxides and enrichment of heavy metals at acidic soil pH

Science.gov (United States)

Mayanna, Sathish; Peacock, Caroline L.; Schäffner, Franziska; Grawunder, Anja; Merten, Dirk; Kothe, Erika; Büchel, Georg

2014-05-01

The precipitation of biogenic Mn oxides at acidic pH is rarely reported and poorly understood, compared to biogenic Mn oxide precipitation at near neutral conditions. Here we identified and investigated the precipitation of biogenic Mn oxides in acidic soil, and studied their role in the retention of heavy metals, at the former uranium mining site of Ronneburg, Germany. The site is characterized by acidic pH, low carbon content and high heavy metal loads including rare earth elements. Specifically, the Mn oxides were present in layers identified by detailed soil profiling and within these layers pH varied from 4.7 to 5.1, Eh varied from 640 to 660 mV and there were enriched total metal contents for Ba, Ni, Co, Cd and Zn in addition to high Mn levels. Using electron microprobe analysis, synchrotron X-ray diffraction and X-ray absorption spectroscopy, we identified poorly crystalline birnessite (δ-MnO2) as the dominant Mn oxide in the Mn layers, present as coatings covering and cementing quartz grains. With geochemical modelling we found that the environmental conditions at the site were not favourable for chemical oxidation of Mn(II), and thus we performed 16S rDNA sequencing to isolate the bacterial strains present in the Mn layers. Bacterial phyla present in the Mn layers belonged to Firmicutes, Actinobacteria and Proteobacteria, and from these phyla we isolated six strains of Mn(II) oxidizing bacteria and confirmed their ability to oxidise Mn(II) in the laboratory. The biogenic Mn oxide layers act as a sink for metals and the bioavailability of these metals was much lower in the Mn layers than in adjacent layers, reflecting their preferential sorption to the biogenic Mn oxide. In this presentation we will report our findings, concluding that the formation of natural biogenic poorly crystalline birnessite can occur at acidic pH, resulting in the formation of a biogeochemical barrier which, in turn, can control the mobility and bioavailability of heavy metals in

Ability of Hand Hygiene Interventions Using Alcohol-Based Hand Sanitizers and Soap To Reduce Microbial Load on Farmworker Hands Soiled during Harvest.

Science.gov (United States)

de Aceituno, Anna Fabiszewski; Bartz, Faith E; Hodge, Domonique Watson; Shumaker, David J; Grubb, James E; Arbogast, James W; Dávila-Aviña, Jorgé; Venegas, Fabiola; Heredia, Norma; García, Santos; Leon, Juan S

2015-11-01

Effective hand hygiene is essential to prevent the spread of pathogens on produce farms and reduce foodborne illness. The U.S. Food and Drug Administration Food Safety Modernization Act Proposed Rule for Produce Safety recommends the use of soap and running water for hand hygiene of produce handlers. The use of alcohol-based hand sanitizer (ABHS) may be an effective alternative hygiene intervention where access to water is limited. There are no published data on the efficacy of either soap or ABHS-based interventions to reduce microbial contamination in agricultural settings. The goal of this study was to assess the ability of two soap-based (traditional or pumice) and two ABHS-based (label-use or two-step) hygiene interventions to reduce microbes (coliforms, Escherichia coli, and Enterococcus spp.) and soil (absorbance of hand rinsate at 600 nm [A600]) on farmworker hands after harvesting produce, compared with the results for a no-hand-hygiene control. With no hand hygiene, farmworker hands were soiled (median A600, 0.48) and had high concentrations of coliforms (geometric mean, 3.4 log CFU per hand) and Enterococcus spp. (geometric mean, 5.3 log CFU per hand) after 1 to 2 h of harvesting tomatoes. Differences in microbial loads in comparison to the loads in the control group varied by indicator organism and hygiene intervention (0 to 2.3 log CFU per hand). All interventions yielded lower concentrations of Enterococcus spp. and E. coli (P hands (P hand washing with soap at reducing indicator organisms on farmworker hands. Based on these results, ABHS is an efficacious hand hygiene solution for produce handlers, even on soiled hands.

Influence of Microsprinkler Irrigation Amount on Water, Soil, and pH Profiles in a Coastal Saline Soil

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Linlin Chu

2014-01-01

Full Text Available Microsprinkler irrigation is a potential method to alleviate soil salinization. After conducting a homogeneous, highly saline, clayey, and coastal soil from the Bohai Gulf in northern China in a column experiment, the results show that the depth of the wetting front increased as the water amount applied increased, low-salinity and low-SAR enlarged after irrigation and water redistribution, and the soil pH increased with an increase in irrigation amount. We concluded that a water amount of 207 mm could be used to reclaim the coastal saline soil in northern China.

Highly effective photothermal chemotherapy with pH-responsive polymer-coated drug-loaded melanin-like nanoparticles

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Zhang C

2017-03-01

Full Text Available Chengwei Zhang,1 Xiaozhi Zhao,1 Suhan Guo,2 Tingsheng Lin,1 Hongqian Guo1 1Department of Urology, Nanjing Drum Tower Hospital, Medical School of Nanjing University, Institute of Urology, Nanjing University, 2School of Public Health, Nanjing Medical University, Nanjing, People’s Republic of China Abstract: Dopamine is a neurotransmitter commonly used in clinical treatment. Polydopamine (PDA has excellent histocompatibility and biosafety and can efficiently convert near-infrared reflection (NIR to thermal energy. In this study, PDA was used as a promising carrier, and pH-responsive polymer-coated drug-loaded PDA nanoparticles (NPs; doxorubicin@poly(allylamine-citraconic anhydride [Dox@PAH-cit]/PDA NPs were developed. As expected, the Dox@PAH-cit/PDA NPs exhibited excellent photothermal efficiency. In addition, at a low pH condition, the loaded Dox was released from the NPs due to the amide hydrolysis of PAH-cit. Upon NIR exposure (808 nm, the temperature of the NP solution rapidly increases to kill tumor cells. Compared with unbound chemotherapy drugs, the NPs have a stronger cell uptake ability. In vivo, the PDA NPs were able to efficiently accumulate at the tumor location. After intravenous administration and NIR exposure, tumor growth was significantly inhibited. In summary, the present investigation demonstrated that the Dox@PAH-cit/PDA NPs presented highly effective photothermal chemotherapy for prostate cancer. Keywords: prostate cancer, photothermal therapy, near-infrared reflection, dopamine, PAH-cit, drug delivery 

Effect of phosphorus on the growth and uptake of fertilizer P by mungbean in different soils of Bangladesh using 32P labelled superphosphate

International Nuclear Information System (INIS)

Ali, M.I.; Bhuiya, E.H.

1979-01-01

A pot experiment was carried out to find out the effects of P on the growth and yield of mungbean and to evaluate the P status in soils collected from 15 locations of Bangladesh using various rates of 32 P labelled superphosphate. Results indicated that P addition increased both straw and grain yields of mungbean on soils of various locations. Phosphorus concentration and the yield of P by plants also tended to increase due to P application. Spectacular increase in the uptake of applied P was recorded with the increasing rates of P application whereas, the uptake of soil P was reduced. 'A' values also tended to increase with the rates of P application. However, the correlation coefficient (r = 0.988) between the mean 'A' values and the NaHCO 3 soluble P in all soils was highly significant. (auth.)

Effects of pH-Induced Changes in Soil Physical Characteristics on the Development of Soil Water Erosion

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Shinji Matsumoto

2018-04-01

Full Text Available Soil water erosion is frequently reported as serious problem in soils in Southeast Asia with tropical climates, and the variations in pH affect the development of the erosion. This study investigated the effects of changes in pH on soil water erosion based on changes in the physical properties of the simulated soils with pH adjusted from 2.0 to 10.0 through artificial rainfall tests. The zeta potential was entirely shifted to positive direction at each pH condition due to Al, Ca, and Mg. In the pH range of 6.0 to 2.0, the aggregation of soil particles resulting from the release of Al3+ from clay minerals and/or molecular attraction between soil particles caused the plastic index (IP of the soil to decrease. The decrease in IP led to the development of soil water erosion at the pH range. When the pH exceeded 6.0, the repulsive force generated by the negative charges on soil particles decreased IP, resulting in accelerated erosion by water. The results suggest that changes in pH causes physical properties of the soil to change through changes of the zeta potential in the clayey soil rich in Al, Ca, and Mg, leading to the development of soil water erosion.

Relation Between pH and Desorption of Cu, Cr, Zn, and Pb from Industrially Polluted Soils

DEFF Research Database (Denmark)

Ottosen, Lisbeth M.; Hansen, Henrik K.; Jensen, Pernille Erland

2009-01-01

Desorption of Cu, Cr, Pb, and Zn from industrially polluted soils as a result of acidification is in focus. The eight soils of the investigation vary greatly in composition and heavy metal concentration/combination. Three soils had elevated concentrations of Cu, Pb, and Zn; regardless of pollution...... level, pollution origin, and soil type, the order for desorption as pH decreased was Zn > Cu > Pb. Turning to a single heavy metal in different soils, there was a huge difference in the pH at which the major desorption started. The variation was most significant for Pb where, e.g., less than 10......% was desorbed at pH 2.5 from one soil, whereas in another soil 60% Pb was desorbed at this pH. Sequential extraction was made and the soils in which a high percentage of Pb was found in the residual phase (adsorbed strongest) was also the soils where less Pb was desorbed at low pH in the desorption experiments...

A novel high drug loading mussel-inspired polydopamine hybrid nanoparticle as a pH-sensitive vehicle for drug delivery.

Science.gov (United States)

Hou, Jie; Guo, Chunlei; Shi, Yuzhi; Liu, Ergang; Dong, Weibing; Yu, Bo; Liu, Shiyuan; Gong, Junbo

2017-11-25

A novel high drug loading pH-cleavable polymer hybrid nanoparticle was prepared via doxorubicin (DOX) grafted onto PEGylated, mussel-inspired polydopamine (PDA) and then coated onto hollow silica nanoparticles for drug delivery. A series of characterization shed light on the formation mechanisms of PDA coatings on hollow silica. We hypothesized that dopamine was first absorbed onto the surface of hollow silica and then began self-polymerization. A Dox-containing thiol moiety was fabricated with conjugation between doxorubicin hydrochloride and Mercaptopropionyalkali with a pH-cleavable hydrozone bond. Using a Michael addition reaction, several Dox-containing thiol moieties were grafted onto the surface of the PDA. The drug loading capacity can reach 35.43%. It can minimize the metabolic problem of silica. The released behavior of Dox can be significantly enhanced at endosomal pH compared to physiological pH. After folate modification, nanoparticles can lead to more cellular endocytosis. Meanwhile animal assays showed that more Dox accumulated in tumor tissue, which can enhanced the cytotoxicity to 4T1 cancer cells with a targeting group compared to free DOX and untargeted groups. Meanwhile, the tumor growth was significantly inhibited. This promising material shows a promising future as a drug delivery system. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitivity of soil phosphorus tests in predicting the potential risk of phosphorus loss from pasture soil

OpenAIRE

H. SOINNE; K. SAARIJÄRVI; M. KARPPINEN

2008-01-01

The objective of this study was to examine the effects of urine and dung additions on the phosphorus (P) chemistry of pasture land and to compare the sensitivity of two soil extraction methods in assessing the P-loading risk. In a field experiment, urine and dung were added to soil in amounts corresponding to single excrement portions and the soil samples, taken at certain intervals, were analysed for pHH2O, acid ammonium acetate extractable P (PAc) and water extractable total P (TPw), and mo...

Excessive application of pig manure increases the risk of P loss in calcic cinnamon soil in China.

Science.gov (United States)

Yang, Yanju; Zhang, Haipeng; Qian, Xiaoqing; Duan, Jiannan; Wang, Gailan

2017-12-31

Soil phosphorus (P) is a critical factor affecting crop yields and water environmental quality. To investigate the degree of loss risk and forms of soil P in calcic cinnamon soil, the P fraction activities in soils were analysed using chemical methods, combined with an in situ field experiment. Seven treatments were set in this study, including control (unfertilized), no P fertilizer (No-P), mineral P fertilizer (Min-P), low (L-Man) and high (H-Man) quantities of pig manure, Min-P+L-Man, and Min-P+H-Man. The results showed that manure fertilizer could not only significantly increase maize yield but could also enhance the accumulation of soil P in organic and inorganic forms. After 23years of repeated fertilization, the soil Olsen-P contents respectively showed 64.7-, 43.7- and 31.9-fold increases in the Min-P+H-Man, Min-P+L-Man and H-Man treatments, while the soil Olsen-P in Min-P treatment only increased 23.7-fold. The soil Olsen-P thresholds ranged from 22.59 to 32.48mgkg -1 in calcic cinnamon soil to maintain a higher maize yield as well as a lower risk of P loss. Therefore, long-term excessive manure application could obviously raise the content of soil Olsen-P and increase the risk of P loss in calcic cinnamon soil. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of humic substances on P sorption capacity of three different soils

Science.gov (United States)

Delgado, Antonio

2010-05-01

Organic matter decreases P sorption by soils. It has been demonstrated the effect of low molecular weight compounds decreasing P adsorption on active surfaces and the effect of humic and fulvic acids inhibiting the precipitation of hydroxyapatite and favouring the formation of more soluble phosphates. This contributes to increase the recovery of applied P fertilizer. The objective of this work was to study the effect of 4 different humic substances (commercially available and provided by Tradecorp Internacional S.A.) on the sorption capacity of three soils differing widely in chemical properties (two calcareous from south Spain, pH 8 and 8.5, and other acidic from Brazil, pH 5.9 and 50 % of exchangeable basic cations). To this end, sorption isotherms were performed at a soil:0.01 M CaCl2 ratio of 1:10 at 6, 30 and 90 days. 2.5 mg of humic substances per g of soil were added to the solution. Data were fitted to the best model and linearized sorption curves for each humic substance were compared with the linearized sorption curve for the control without humic substances application (intersection point and slopes). Soil from Brazil showed a much higher sorption capacity (400 mg P kg-1 soil sorbed at 1 mg L-1 of P in the solution at 1 day) than the other two soils (50 and 100 mg P kg-1). Slow reactions significantly contributed to P sorption in the three soils, amounts sorbed at 90 days being twice than those sorbed at 1 day. Two of the products increased P sorption in the soil from Brazil at 1 day. At 90 days all the products increased P sorption significantly. This increased P sorption can be only explained by metal complexation by the substances applied, which may result in organo-metallic compounds with a high P sorption capacity. This effect was independent of the proportion of humic and fulvic acids in the applied products because the amounts of metal complexed by these compouds depend on the amount of functional groups to coordinate with metals. In the Spanish

CURVAS DE TRANSFERENCIA DE CARGA HORIZONTAL p-y PARA SUELOS LIMOSOS LOÉSSICOS CURVAS DE TRANSFERÊNCIA DE CARGA HORIZONTAL p-y PARA SOLOS LIMOSOS LOÉSSICOS HORIZOTAL LOAD TRANSFERENCE p-y CURVE FOR SILTY LOESS SOILS

Directory of Open Access Journals (Sweden)

PEDRO A ARRÚA

2009-07-01

a cargas laterais para a construção de curvas de transferência de carga horizontal p-y em condição de umidade natural e saturado. Finalmente, se analisam dois casos de estudo, onde se avalia computacionalmente a resposta de um pilotis instalado em uma camada de limo loéssico que sofre humedecimento localizado. Os resultados mostram a importância de considerar o aumento acidental de umidade no perfil quando os pilotis se encontram instalados em solos de características instáveis.Drilled deep foundations may be subjected to horizontal loads. Under this condition, the behavior analysis is complicated due to the tridimensionality of the problem. H ow ever, the models used in engineering practice often reduce the analysis to two dimensions. In this paper the procedure proposed by Matlock and Reese (1960 is modified for its applicability to loess soils. An alternative to establish the variation of the horizontal subgrade reaction module as a function of depth, for soils with intermediate characteristics between sands and clays, such as silty soils, is developed. An analogy between the cavity expansion and deflection of a pile subjected to lateral loads is established for construction of horizontal charge transfer p-y curves under natural humidity and saturated conditions. Finally, two study cases are analyzed, where the response of pile installed on loess silty soil layer suffering localized wetting is computationally evaluated. Results show the importance of considering the accidental wetting increase, when the piles are installed in unstable soils.

Biodegradation of Aged Residues of Atrazine and Alachlor in a Mix-Load Site Soil by Fungal Enzymes

Directory of Open Access Journals (Sweden)

Anastasia E. M. Chirnside

2011-01-01

Full Text Available Soils from bulk pesticide mixing and loading (mix-load sites are often contaminated with a complex mixture of pesticides, herbicides, and other organic compounds used in pesticide formulations that limits the success of remediation efforts. Therefore, there is a need to find remediation strategies that can successfully clean up these mix-load site soils. This paper examined the degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT and alachlor (2-chloro-2, 6-diethyl-N-[methoxymethyl]-acetanilide in contaminated mix-load site soil utilizing an extracellular fungal enzyme solution derived from the white rot fungus, Phanerochaete chrysosporium, grown in a packed bed bioreactor. Thirty-two percent of AT and 54% of AL were transformed in the biometers. The pseudo first-order rate constant for AT and AL biodegradation was 0.0882 d−1 and 0.2504 d−1, respectively. The half-life (1/2 for AT and AL was 8.0 and 3.0 days, respectively. Compared to AT, the initial disappearance of AL proceeded at a faster rate and resulted in a greater amount of AL transformed. Based on the net Co2 evolved from the biometers, about 4% of the AT and AL initially present in the soil was completely mineralized.

Forest wildfire increases soil microbial biomass C:N:P stoichiometry in long-term effects

Science.gov (United States)

Zhou, Xuan

2017-04-01

Boreal forest fire strongly influences carbon (C) stock in permafrost soil by thawing permafrost table which accelerated microbe decomposition process. We studied soil microbial biomass stoichiometry in a gradient of four (3 yr, 25 yr, 46 yr and more than 100 yr) ages since fire in Canada boreal forest. Soil microbial biomass (MB) in long-term after fire is significantly higher than in short-term. MB C and nitrogen (N) were mainly dominated by corresponding soil element concentration and inorganic P, while MB phosphorus (P) changes were fully explained by soil N. Fire ages and soil temperature positively increased MB N and P, indicating the negative impact by fire. Microbial C:N:P gradually increased with fire ages from 15:2:1 to 76:6:1 and then drop down to 17:2:1 in the oldest fire ages. The degree of homeostasis of microbial C, N and P are close to 1 indicates non-homoeostasis within microbial elements, while it of C:N:P is close to 8 shows a strong homeostasis within element ratios and proved microbial stoichiometric ratio is not driven by soil element ratios. In conclusion, i) microbial biomass elements highly depends on soil nutrient supply rather than fire ages; ii) wildfire decreased microbial stoichiometry immediate after fire but increased with years after fire (YF) which at least 3 times higher than > 100 fire ages; iii) microbial biomass C, N and P deviated from strict homeostasis but C:N:P ratio reflects stronger homeostasis.

Bioavailable soil P as a main key for sustainable agriculture: its functional model determined using isotopic tracers

Energy Technology Data Exchange (ETDEWEB)

Fardeau, J.C.; Guiraud, G.; Marol, C.

1994-12-31

Sustainable agriculture is defined in many ways. In all of them, two main complementary concepts appear: this agriculture must firstly satisfy the human needs of foods for the present and secondly must not compromise the ability for the future generations to meet their needs. Therefore, concerning P, the sustainability in an ecosystem can be maintained if, and only if: (i) bioavailable soil P is not a limiting factor of crop yields in the considered conditions; (ii) all the parameters describing the available soil P will be unmodified each time that P is simultaneously taken by crops and returned to soils; (iii) P inputs and outputs must be without negative consequences on environment. Whatever the ecosystem, P nutrition can be described in terms of fluxes of P between soil and plant roots. The isotopic exchange method gives informations not only on bioavailable soil P but also on potential fluxes of P between soil and soil-solution. As roots take phosphorus in the soil solution it is concluded that this method can be used to predict not only potential P uptake by plants or crops in native soils but also the contribution to crop nutrition of a P application in soil. Isotopic tracers of P seem to be, at the present time, the simplest tool useful to describe, with a high accuracy, the main link of P cycle in sustainable agriculture: the bioavailable soil P. (authors). 9 refs., 1 fig., 1 tab. (authors).

Bioavailable soil P as a main key for sustainable agriculture: its functional model determined using isotopic tracers

International Nuclear Information System (INIS)

Fardeau, J.C.; Guiraud, G.; Marol, C.

1994-01-01

Sustainable agriculture is defined in many ways. In all of them, two main complementary concepts appear: this agriculture must firstly satisfy the human needs of foods for the present and secondly must not compromise the ability for the future generations to meet their needs. Therefore, concerning P, the sustainability in an ecosystem can be maintained if, and only if: (i) bioavailable soil P is not a limiting factor of crop yields in the considered conditions; (ii) all the parameters describing the available soil P will be unmodified each time that P is simultaneously taken by crops and returned to soils; (iii) P inputs and outputs must be without negative consequences on environment. Whatever the ecosystem, P nutrition can be described in terms of fluxes of P between soil and plant roots. The isotopic exchange method gives informations not only on bioavailable soil P but also on potential fluxes of P between soil and soil-solution. As roots take phosphorus in the soil solution it is concluded that this method can be used to predict not only potential P uptake by plants or crops in native soils but also the contribution to crop nutrition of a P application in soil. Isotopic tracers of P seem to be, at the present time, the simplest tool useful to describe, with a high accuracy, the main link of P cycle in sustainable agriculture: the bioavailable soil P. (authors). 9 refs., 1 fig., 1 tab. (authors)

In situ measurements reveal extremely low pH in soil

DEFF Research Database (Denmark)

Nielsen, Knud Erik; Loibide, Amaia Irixar; Nielsen, Lars Peter

2017-01-01

We measured pH in situ in the top organic soil horizons in heathland and pine forest and found values between 2.6 and 3.2. This was 0.5e0.8 units lower than concurrent laboratory pH measurements of the same soil, which raises questions about the interpretation of pH measurements. We propose that ...... that the higher pH recorded by standard laboratory methods may be due to buffering ions from soil biota released from drying, grinding and rewetting of soil samples, whereas the in situ pH reflects the correct level of acidification....

Analyzing the mobility in granular forms of P fertilizer in Brazilians soils under laboratory conditions

International Nuclear Information System (INIS)

Castro, Robson C. de; Oliveira, Davi Ferreira de; Oliveira, Luis Fernando de; Anjos, Marcelino Jose dos

2013-01-01

Phosphorus is an essential nutrient for plant growth. Million of tones of P are applied to the soils annually. However, only a small fraction of the P applied with fertilizers is taken up by crops in the year of application, and the effectiveness of any residual P fertilizer declines with time. To improve our understanding of the mechanisms underlying this response to P in the field, we have studied the mobility of P from 3 different fertilizes: monoammonium phosphate (MAP), polymer coated monoammonium phosphate (MAPp) and Organomineral phosphate (OMP) applied on high weathered soil samples in a Petri dish experiment. Total Reflection X-Ray Fluorescence (TXRF) was used to determine the P diffusive flux at different distances (0 - 7.5, 7.5 – 13.5, 13.5 – 25.5 and 25.5 – 43 mm) from granular fertilizer. TXRF analyses were performed at the X-Ray Fluorescence Beamline D09B at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, Sao Paulo, using a polychromatic beam with maximum energy of 20 keV for the excitation and an Ultra-LEGe detector with resolution of 148 eV at 5.9 keV. Besides that, the detections were performed in a high vacuum chamber (2.5 x 10-5 mbar) to avoid air absorption. After a period of five weeks, the total P concentration increased in the soil sampled 7.5 to 13.5 mm from the fertilizer showing a diffusive flux of P. About 20% (considering MAP and MAPp) of the total P applied diffused out of the central soil ring. Different sources showed differences in diffusive flux of P. Soil pH also influenced diffusive flux of P showing higher flux on lower pH soils. (author)

Analysis of underground concrete pipelines subjected to seismic high-frequency loads

OpenAIRE

Abbasiverki, Roghayeh

2016-01-01

Buried pipelines are tubular structures that are used for transportation of important liquid materials and gas in order to provide safety for human life. During an earthquake, imposed loads from soil deformations on concrete pipelines may cause severe damages, possibly causing disturbance in vital systems, such as cooling of nuclear power facilities. The high level of safety has caused a demand for reliable seismic analyses, also for structures built in the regions that have not traditionally...

On seasonal fluctuations of available Olsen P in soils

Directory of Open Access Journals (Sweden)

Vincenzo Tabaglio

Full Text Available The likelihood of a strong seasonal effect on the analytical results of soil chemical tests has been substantiated by several findings. The occurrence of such a trouble would heavily affect the routine work of chemical laboratories dealing with hundreds or thousands of soil samples every year and would possibly interfere even with current timing of soil sampling and testing in agronomical research. Soils from four different experimental fields were sampled and analyzed for Olsen P test through the growing season of both spring-summer crops (maize and autumn-spring crops (soft wheat. To avoid the cross effect of recent P applications, samples were collected only from the control plots, with no P applied. In a first long-time experiment the level of Olsen P was followed in three soils during two years, while in a second experiment the study considered two different soils for a couple of years each. The amount of extractable (available Olsen P showed significant fluctuations-with-time in four years out of six. The observed variations seems entirely due to P absorption by crops, as they appeared in the final samplings during the cropping season. The amount of decrease was nearly always small, less than 1-1.5 mg kg-1 soil, and consistent with the reduction of the available pool which is to be expected as crops gradually take up nutrients. As far as Olsen P is concerned, no evidence was found for the occurrence of erratic seasonal variations such as those previously reported. As soil samples for advisory purposes are usually taken at different times of the year, it seems reassuring that no complications are to be expected about information needed to interpret the results of chemical tests.

Solubility of lead and copper in biochar-amended small arms range soils: influence of soil organic carbon and pH.

Science.gov (United States)

Uchimiya, Minori; Bannon, Desmond I

2013-08-14

Biochar is often considered a strong heavy metal stabilizing agent. However, biochar in some cases had no effects on, or increased the soluble concentrations of, heavy metals in soil. The objective of this study was to determine the factors causing some biochars to stabilize and others to dissolve heavy metals in soil. Seven small arms range soils with known total organic carbon (TOC), cation exchange capacity, pH, and total Pb and Cu contents were first screened for soluble Pb and Cu concentrations. Over 2 weeks successive equilibrations using weak acid (pH 4.5 sulfuric acid) and acetate buffer (0.1 M at pH 4.9), Alaska soil containing disproportionately high (31.6%) TOC had nearly 100% residual (insoluble) Pb and Cu. This soil was then compared with sandy soils from Maryland containing significantly lower (0.5-2.0%) TOC in the presence of 10 wt % (i) plant biochar activated to increase the surface-bound carboxyl and phosphate ligands (PS450A), (ii) manure biochar enriched with soluble P (BL700), and (iii) unactivated plant biochars produced at 350 °C (CH350) and 700 °C (CH500) and by flash carbonization (corn). In weak acid, the pH was set by soil and biochar, and the biochars increasingly stabilized Pb with repeated extractions. In pH 4.9 acetate buffer, PS450A and BL700 stabilized Pb, and only PS450A stabilized Cu. Surface ligands of PS450A likely complexed and stabilized Pb and Cu even under acidic pH in the presence of competing acetate ligand. Oppositely, unactivated plant biochars (CH350, CH500, and corn) mobilized Pb and Cu in sandy soils; the putative mechanism is the formation of soluble complexes with biochar-borne dissolved organic carbon. In summary, unactivated plant biochars can inadvertently increase dissolved Pb and Cu concentrations of sandy, low TOC soils when used to stabilize other contaminants.

Phosphate fertilizers with varying water-solubility applied to Amazonian soils: II. Soil P extraction methods

International Nuclear Information System (INIS)

Muraoka, T.; Brasil, E.C.; Scivittaro, W.B.

2002-01-01

A pot experiment was carried out under greenhouse conditions at the Centro de Energia Nuclear na Agricultura, Piracicaba (SP, Brazil), to evaluate the phosphorus availability of different phosphate sources in five Amazonian soils. The soils utilized were: medium texture Yellow Latosol, clayey Yellow Latosol, very clayey Yellow Latosol, clayey Red-Yellow Podzolic and very clayey Red-Yellow Podzolic. Four phosphate sources were applied: triple superphosphate, ordinary Yoorin thermophosphate, coarse Yoorin termo-phosphate and North Carolina phosphate rock at P rates of 0, 40, 80 and 120 mg kg -1 soil. The dry matter yield and the amount of P taken up by cowpea and rice were correlated with the extractable P by anionic exchangeable resin, Mehlich-1, Mehlich-3 and Bray-I. The results showed that the extractable P by Mehlich-1 was higher in the soils amended with North Carolina rock phosphate. Irrespective of the phosphorus sources used, the Mehlich-3 extractant showed close correlation with plant response. The Mehlich-3 and Bray-I extractants were more sensitive to soil variations. The Mehlich-3 extractant was more suitable in predicting the P availability to plants in the different soils and phosphorus sources studied. (author)

Soil solution interactions may limit Pb remediation using P amendments in an urban soil

Science.gov (United States)

Lead (Pb) contaminated soils are a potential exposure hazard to the public. Amending soils with phosphorus (P) may reduce Pb soil hazards. Soil from Cleveland, OH containing 726 ± 14 mg Pb kg-1 was amended in a laboratory study with bone meal and triple super phospha...

Effect of pH and soil structure on transport of sulfonamide antibiotics in agricultural soils.

Science.gov (United States)

Park, Jong Yol; Huwe, Bernd

2016-06-01

We investigated the effect of solution pH and soil structure on transport of sulfonamide antibiotics (sulfamethoxazole, sulfadimethoxine and sulfamethazine) in combination with batch sorption tests and column experiments. Sorption isotherms properly conformed to Freundlich model, and sorption potential of the antibiotics is as follows; sulfadimethoxine > sulfamethoxazole > sulfamethazine. Decreasing pH values led to increased sorption potential of the antibiotics on soil material in pH range of 4.0-8.0. This likely resulted from abundance of neutral and positive-charged sulfonamides species at low pH, which electrostatically bind to sorption sites on soil surface. Due to destruction of macropore channels, lower hydraulic conductivities of mobile zone were estimated in the disturbed soil columns than in the undisturbed soil columns, and eventually led to lower mobility of the antibiotics in disturbed column. The results suggest that knowledge of soil structure and solution condition is required to predict fate and distribution of sulfonamide antibiotics in environmental matrix. Copyright © 2016 Elsevier Ltd. All rights reserved.

Blast load effects research in dry and wet soil

CSIR Research Space (South Africa)

Ahmed, R

2014-09-01

Full Text Available stream_source_info Ahmed_2014_ABSTRACT.pdf.txt stream_content_type text/plain stream_size 904 Content-Encoding UTF-8 stream_name Ahmed_2014_ABSTRACT.pdf.txt Content-Type text/plain; charset=UTF-8 South African Ballistics... Organisation Conference, Zebra Country Lodge, Gauteng, South Africa, 29 September – 1 October 2014 BLAST LOAD EFFECTS RESEARCH IN DRY AND WET SOIL R Ahmed and ME Miyambo Landward Sciences, Defence Peace Safety and Security, CSIR, PO Box 395, Pretoria...

The Bearing Capacity of Strip Footings in Cohesionless Soil Subject to Eccentric and Inclined Loads

DEFF Research Database (Denmark)

Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

2014-01-01

Lower bound calculations based on the finite element method is used to determine the bearing capacity of a strip foundation subjected to an inclined, eccentric load on cohesionless soil with varying surcharges and with friction angles 25, 30 and 35°. The soil is assumed perfectly plastic following...... the Mohr-Coulomb failure criterion. The results are reported as graphs showing the bearing capacity as a function of the friction angle, the eccentricity, inclination and the surcharge. The results have been compared with the Eurocode 7 and for smaller eccentricities, except in the case of no surcharge......, the lower bound values are the greater, the discrepancy increasing with growing surcharge. Positive load inclinations has a negative effect for smaller eccentricities but may have a beneficial effect on the bearing capacity for greater eccentricities. Negative load inclinations have the opposite effect...

Biogas-pH automation control strategy for optimizing organic loading rate of anaerobic membrane bioreactor treating high COD wastewater.

Science.gov (United States)

Yu, Dawei; Liu, Jibao; Sui, Qianwen; Wei, Yuansong

2016-03-01

Control of organic loading rate (OLR) is essential for anaerobic digestion treating high COD wastewater, which would cause operation failure by overload or less efficiency by underload. A novel biogas-pH automation control strategy using the combined gas-liquor phase monitoring was developed for an anaerobic membrane bioreactor (AnMBR) treating high COD (27.53 g·L(-1)) starch wastewater. The biogas-pH strategy was proceeded with threshold between biogas production rate >98 Nml·h(-1) preventing overload and pH>7.4 preventing underload, which were determined by methane production kinetics and pH titration of methanogenesis slurry, respectively. The OLR and the effluent COD were doubled as 11.81 kgCOD·kgVSS(-1)·d(-1) and halved as 253.4 mg·L(-1), respectively, comparing with a constant OLR control strategy. Meanwhile COD removal rate, biogas yield and methane concentration were synchronously improved to 99.1%, 312 Nml·gCODin(-1) and 74%, respectively. Using the biogas-pH strategy, AnMBR formed a "pH self-regulation ternary buffer system" which seizes carbon dioxide and hence provides sufficient buffering capacity. Copyright © 2015 Elsevier Ltd. All rights reserved.

In situ stabilization of trace metals in a copper-contaminated soil using P-spiked Linz-Donawitz slag.

Science.gov (United States)

Negim, Osama; Mench, Michel; Bes, Clémence; Motelica-Heino, Mikael; Amin, Fouad; Huneau, Frédéric; Le Coustumer, Philippe

2012-03-01

A former wood exploitation revealing high Cu and As concentration of the soils served as a case study for assisted phytoextraction. P-spiked Linz-Donawitz (LD) slag was used as a soil additive to improve physico-chemical soil properties and in situ stabilize Cu and other trace metals in a sandy Cu-contaminated soil (630 mg kg⁻¹ soil). The LD slag was incorporated into the contaminated soil to consist four treatments: 0% (T1), 1% (T2), 2% (T3), and 4% (T4). A similar uncontaminated soil was used as a control (CTRL). After a 1-month reaction period, potted soils were used for a 2-week growth experiment with dwarf beans. Soil pH increased with the incorporation rate of LD slag. Similarly the soil electrical conductivity (EC, in millisiemens per centimetre) is ameliorated. Bean plants grown on the untreated soil (T1) showed a high phytotoxicity. All incorporation rates of LD slag increased the root and shoot dry weight yields compared to the T1. The foliar Ca concentration of beans was enhanced for all LD slag-amended soil, while the foliar Mg, K, and P concentrations were not increased. Foliar Cu, Zn, and Cr concentrations of beans decreased with the LD slag incorporation rate. P-spiked LD slag incorporation into polluted soil allow the bean growth and foliar Ca concentration, but also to reduce foliar Cu concentration below its upper critical value avoiding an excessive soil EC and Zn deficiency. This dual effect can be of interest for soil remediation at larger scale.

High thermal load receiving heat plate

International Nuclear Information System (INIS)

Shibutani, Jun-ichi; Shibayama, Kazuhito; Yamamoto, Keiichi; Uchida, Takaho.

1993-01-01

The present invention concerns a high thermal load heat receiving plate such as a divertor plate of a thermonuclear device. The high thermal load heat receiving plate of the present invention has a cooling performance capable of suppressing the temperature of an armour tile to less than a threshold value of the material against high thermal loads applied from plasmas. Spiral polygonal pipes are inserted in cooling pipes at a portion receiving high thermal loads in the high temperature load heat receiving plate of the present invention. Both ends of the polygonal pipes are sealed by lids. An area of the flow channel in the cooling pipes is thus reduced. Heat conductivity on the cooling surface of the cooling pipes is increased in the high thermal load heat receiving plate having such a structure. Accordingly, temperature elevation of the armour tile can be suppressed. (I.S.)

Soil contamination of plant surfaces from grazing and rainfall interactions

International Nuclear Information System (INIS)

Hinton, T.G.; Stoll, J.M.; Tobler, L.

1995-01-01

Contaminants often attach to soil particles, and their subsequent environmental transport is largely determined by processes that govern soil movement. We examined the influence of grazing intensity on soil contamination of pastures. Four different grazing densities of sheep were tested against an ungrazed control plot. Scandium concentrations were determined by neutron activation analysis and was used as a tracer of soil adhesion on vegetation. Soil loadings ( g soil kg -1 dry plant) increased 60% when grazing intensity was increased by a factor of four (p 0.003). Rain and wind removed soil from vegetation in the ungrazed control plots, but when grazing sheep were present, an increase in rain from 0.3 to 9.7 mm caused a 130% increase in soil contamination. Multiple regression was used to develop an equation that predicts soil loadings as a function of grazing density, rainfall and wind speed (p = 0.0001, r 2 = 0.78). The model predicts that if grazing management were to be used as a tool to reduce contaminant intake from inadvertent consumption of resuspended soil by grazing animals, grazing densities would have to be reduced 2.5 times to reduce soil loadings by 50%. (author)

Fertilization Shapes Bacterial Community Structure by Alteration of Soil pH

Directory of Open Access Journals (Sweden)

Yuting Zhang

2017-07-01

Full Text Available Application of chemical fertilizer or manure can affect soil microorganisms directly by supplying nutrients and indirectly by altering soil pH. However, it remains uncertain which effect mostly shapes microbial community structure. We determined soil bacterial diversity and community structure by 454 pyrosequencing the V1-V3 regions of 16S rRNA genes after 7-years (2007–2014 of applying chemical nitrogen, phosphorus and potassium (NPK fertilizers, composted manure or their combination to acidic (pH 5.8, near-neutral (pH 6.8 or alkaline (pH 8.4 Eutric Regosol soil in a maize-vegetable rotation in southwest China. In alkaline soil, nutrient sources did not affect bacterial Operational Taxonomic Unit (OTU richness or Shannon diversity index, despite higher available N, P, K, and soil organic carbon in fertilized than in unfertilized soil. In contrast, bacterial OTU richness and Shannon diversity index were significantly lower in acidic and near-neutral soils under NPK than under manure or their combination, which corresponded with changes in soil pH. Permutational multivariate analysis of variance showed that bacterial community structure was significantly affected across these three soils, but the PCoA ordination patterns indicated the effect was less distinct among nutrient sources in alkaline than in acidic and near-neural soils. Distance-based redundancy analysis showed that bacterial community structures were significantly altered by soil pH in acidic and near-neutral soils, but not by any soil chemical properties in alkaline soil. The relative abundance (% of most bacterial phyla was higher in near-neutral than in acidic or alkaline soils. The most dominant phyla were Proteobacteria (24.6%, Actinobacteria (19.7%, Chloroflexi (15.3% and Acidobacteria (12.6%; the medium dominant phyla were Bacterioidetes (5.3%, Planctomycetes (4.8%, Gemmatimonadetes (4.5%, Firmicutes (3.4%, Cyanobacteria (2.1%, Nitrospirae (1.8%, and candidate division TM7 (1

Fertilization Shapes Bacterial Community Structure by Alteration of Soil pH.

Science.gov (United States)

Zhang, Yuting; Shen, Hong; He, Xinhua; Thomas, Ben W; Lupwayi, Newton Z; Hao, Xiying; Thomas, Matthew C; Shi, Xiaojun

2017-01-01

Application of chemical fertilizer or manure can affect soil microorganisms directly by supplying nutrients and indirectly by altering soil pH. However, it remains uncertain which effect mostly shapes microbial community structure. We determined soil bacterial diversity and community structure by 454 pyrosequencing the V1-V3 regions of 16S rRNA genes after 7-years (2007-2014) of applying chemical nitrogen, phosphorus and potassium (NPK) fertilizers, composted manure or their combination to acidic (pH 5.8), near-neutral (pH 6.8) or alkaline (pH 8.4) Eutric Regosol soil in a maize-vegetable rotation in southwest China. In alkaline soil, nutrient sources did not affect bacterial Operational Taxonomic Unit (OTU) richness or Shannon diversity index, despite higher available N, P, K, and soil organic carbon in fertilized than in unfertilized soil. In contrast, bacterial OTU richness and Shannon diversity index were significantly lower in acidic and near-neutral soils under NPK than under manure or their combination, which corresponded with changes in soil pH. Permutational multivariate analysis of variance showed that bacterial community structure was significantly affected across these three soils, but the PCoA ordination patterns indicated the effect was less distinct among nutrient sources in alkaline than in acidic and near-neural soils. Distance-based redundancy analysis showed that bacterial community structures were significantly altered by soil pH in acidic and near-neutral soils, but not by any soil chemical properties in alkaline soil. The relative abundance (%) of most bacterial phyla was higher in near-neutral than in acidic or alkaline soils. The most dominant phyla were Proteobacteria (24.6%), Actinobacteria (19.7%), Chloroflexi (15.3%) and Acidobacteria (12.6%); the medium dominant phyla were Bacterioidetes (5.3%), Planctomycetes (4.8%), Gemmatimonadetes (4.5%), Firmicutes (3.4%), Cyanobacteria (2.1%), Nitrospirae (1.8%), and candidate division TM7 (1

Effect of acid rain pH on leaching behavior of cement stabilized lead-contaminated soil.

Science.gov (United States)

Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Liu, Zhao-Peng; Jin, Fei

2014-04-30

Cement stabilization is a practical approach to remediate soils contaminated with high levels of lead. However, the potential for leaching of lead out of these stabilized soils under variable acid rain pH conditions is a major environmental concern. This study investigates the effects of acid rain on the leaching characteristics of cement stabilized lead contaminated soil under different pH conditions. Clean kaolin clay and the same soil spiked with 2% lead contamination are stabilized with cement contents of 12 and 18% and then cured for 28 days. The soil samples are then subjected to a series of accelerated leaching tests (or semi-dynamic leaching tests) using a simulated acid rain leachant prepared at pH 2.0, 4.0 or 7.0. The results show that the strongly acidic leachant (pH ∼2.0) significantly altered the leaching behavior of lead as well as calcium present in the soil. However, the differences in the leaching behavior of the soil when the leachant was mildly acidic (pH ∼4.0) and neutral (pH ∼7.0) prove to be minor. In addition, it is observed that the lead contamination and cement content levels can have a considerable impact on the leaching behavior of the soils. Overall, the leachability of lead and calcium is attributed to the stability of the hydration products and their consequent influence on the soil buffering capacity and structure. Copyright © 2014 Elsevier B.V. All rights reserved.

High-Frequency Axial Fatigue Test Procedures for Spectrum Loading

Science.gov (United States)

2016-07-20

cycle runout limit. PURPOSE 2. To develop the capability to perform High-Frequency (H-F) Spectrum Fatigue tests, an in- house Basic and...response of the test specimen to the command input signal for load cycling . These cycle -by- cycle errors accumulate over the life of the test specimen...fatigue life model. It is expected that the cycle -by- cycle P-V error may vary substantially depending on the load spectrum content, the compensation

Organic Residues Affect Soil P Availability, Cowpea Yield And ...

African Journals Online (AJOL)

SH

control treatment, and 3.37 mg kg soil-1 for maize stover, which rather immobilized P throughout the ... potentially involves lower production costs ... controlling reduction of soil P-sorption capacity .... thick polyethylene film (to allow gas but not.

Modelling soil properties in a crop field located in Croatia

Science.gov (United States)

Bogunovic, Igor; Pereira, Paulo; Millan, Mesic; Percin, Aleksandra; Zgorelec, Zeljka

2016-04-01

Development of tillage activities had negative effects on soil quality as destruction of soil horizons, compacting and aggregates destruction, increasing soil erosion and loss of organic matter. For a better management in order to mitigate the effects of intensive soil management in land degradation it is fundamental to map the spatial distribution of soil properties (Brevik et al., 2016). The understanding the distribution of the variables in space is very important for a sustainable management, in order to identify areas that need a potential intervention and decrease the economic losses (Galiati et al., 2016). The objective of this work is study the spatial distribution of some topsoil properties as clay, fine silt, coarse silt, fine sand, coarse sand, penetration resistance, moisture and organic matter in a crop field located in Croatia. A grid with 275x25 (625 m2) was designed and a total of 48 samples were collected. Previous to data modelling, data normality was checked using the Shapiro wilk-test. As in previous cases (Pereira et al., 2015), data did not followed the normal distribution, even after a logarithmic (Log), square-root, and box cox transformation. Thus, for modeling proposes, we used the log transformed data, since was the closest to the normality. In order to identify groups among the variables we applied a principal component analysis (PCA), based on the correlation matrix. On average clay content was 15.47% (±3.23), fine silt 24.24% (±4.08), coarse silt 35.34% (±3.12), fine sand 20.93% (±4.68), coarse sand 4.02% (±1.69), penetration resistance 0.66 MPa (±0.28), organic matter 1.51% (±0.25) and soil moisture 32.04% (±3.27). The results showed that the PCA identified three factors explained at least one of the variables. The first factor had high positive loadings in soil clay, fine silt and organic matter and a high negative loading in fine sand. The second factor had high positive loadings in coarse sand and moisture and a high

Spatial variability of soil pH based on GIS combined with geostatistics in Panzhihua tobacco area

International Nuclear Information System (INIS)

Du Wei; Wang Changquan; Li Bing; Li Qiquan; Du Qian; Hu Jianxin; Liu Chaoke

2012-01-01

GIS and geostatistics were utilized to study the spatial variability of soil pH in Panzhihua tobacco area. Results showed that pH values in this area ranged from 4.5 to 8.3, especially 5.5 to 6.5, and in few areas were lower than 5.0 or higher than 7.0 which can meet the need of high-quality tobacco production. The best fitting model of variogram was exponential model with the nugget/sill of soil pH in 13.61% indicating strong spatial correlation. The change process was 5.40 km and the coefficient of determination was 0.491. The spatial variability of soil pH was mainly caused by structural factors such as cane, topography and soil type. The soil pH in Panzhihua tobacco area also showed a increasing trend of northwest to southeast trend. The pH of some areas in Caochang, Gonghe and Yumen were lower, and in Dalongtan were slightly higher. (authors)

Surfactant flushing remediation of o-dichlorobenzene and p-dichlorobenzene contaminated soil.

Science.gov (United States)

Pei, Guangpeng; Zhu, Yuen; Cai, Xiatong; Shi, Weiyu; Li, Hua

2017-10-01

Surfactant-enhanced remediation is used to treat dichlorobenzene (DCB) contaminated soil. In this study, soil column experiments were conducted to investigate the removal efficiencies of o-dichlorobenzene (o-DCB) and p-dichlorobenzene (p-DCB) from contaminated soil using micellar solutions of biosurfactants (saponin, alkyl polyglycoside) compare to a chemically synthetic surfactant (Tween 80). Leachate was collected and analyzed for o-DCB and p-DCB content. In addition, soil was analyzed to explore the effect of surfactants on soil enzyme activities. Results showed that the removal efficiency of o-DCB and p-DCB was highest for saponin followed by alkyl polyglycoside and Tween 80. The maximum o-DCB and p-DCB removal efficiencies of 76.34% and 80.43%, respectively, were achieved with 4 g L -1 saponin solution. However, an opposite result was observed in the cumulative mass of o-DCB and p-DCB in leachate. The cumulative extent of o-DCB and p-DCB removal by the biosurfactants saponin and alkyl polyglycoside was lower than that of the chemically synthetic surfactant Tween 80 in leachate. Soil was also analyzed to explore the effect of surfactants on soil enzyme activities. The results indicated that surfactants were potentially effective in facilitating soil enzyme activities. Thus, it was confirmed that the biosurfactants saponin and alkyl polyglycoside could be used for remediation of o-DCB and p-DCB contaminated soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Estimates of critical acid loads and exceedances for forest soils across the conterminous United States

Science.gov (United States)

Steven G. McNulty; Erika C. Cohen; Jennifer A. Moore Myers; Timothy J. Sullivan; Harbin Li

2007-01-01

Concern regarding the impacts of continued nitrogen and sulfur deposition on ecosystem health has prompted the development of critical acid load assessments for forest soils. A critical acid load is a quantitative estimate of exposure to one or more pollutants at or above which harmful acidification-related effects on sensitive elements of the environment occur. A...

Pinus pinaster seedlings and their fungal symbionts show high plasticity in phosphorus acquisition in acidic soils.

Science.gov (United States)

Ali, M A; Louche, J; Legname, E; Duchemin, M; Plassard, C

2009-12-01

Young seedlings of maritime pine (Pinus pinaster Soland in Aït.) were grown in rhizoboxes using intact spodosol soil samples from the southwest of France, in Landes of Gascogne, presenting a large variation of phosphorus (P) availability. Soils were collected from a 93-year-old unfertilized stand and a 13-year-old P. pinaster stand with regular annual fertilization of either only P or P and nitrogen (N). After 6 months of culture in controlled conditions, different morphotypes of ectomycorrhiza (ECM) were used for the measurements of acid phosphatase activity and molecular identification of fungal species using amplification of the ITS region. Total biomass, N and P contents were measured in roots and shoots of plants. Bicarbonate- and NaOH-available inorganic P (Pi), organic P (Po) and ergosterol concentrations were measured in bulk and rhizosphere soil. The results showed that bulk soil from the 93-year-old forest stand presented the highest Po levels, but relatively higher bicarbonate-extractable Pi levels compared to 13-year-old unfertilized stand. Fertilizers significantly increased the concentrations of inorganic P fractions in bulk soil. Ergosterol contents in rhizosphere soil were increased by fertilizer application. The dominant fungal species was Rhizopogon luteolus forming 66.6% of analysed ECM tips. Acid phosphatase activity was highly variable and varied inversely with bicarbonate-extractable Pi levels in the rhizosphere soil. Total P or total N in plants was linearly correlated with total plant biomass, but the slope was steep only between total P and biomass in fertilized soil samples. In spite of high phosphatase activity in ECM tips, P availability remained a limiting nutrient in soil samples from unfertilized stands. Nevertheless young P. pinaster seedlings showed a high plasticity for biomass production at low P availability in soils.

Soil pro consolidation load and settlement computation; Preconsolidacion de los suelos y calculo de asentamiento

Energy Technology Data Exchange (ETDEWEB)

Delgado Martinez, D. E.

2009-07-01

It is estimated that cohesive soils are present in about in about 80% of the Cuban territory. Most of these soils are pre consolidated as a result of the country's geo-environmental conditions. That's why it is important, in the Cuban context, to determine accurately the soil pre consolidation load, correct the oedometric curve and apply these concepts to settlement computation. In this paper, a study is presented to define how to estimate the pre consolidation pressure by using several methods. A database was created. It consisted of 102 pre consolidated soils, which are typical from the central region of Cuban. These soil we analyzed by several Cuban geotechnical research centers. (Author) 12 refs.

Contribution of soil-32P, fertilizer-32P and VA mycorrhizal fungi to phosphorus nutrition of corn plant

International Nuclear Information System (INIS)

Feng Gu; Yang Maoqiu; Bai Dengsha; Huang Quansheng

1997-01-01

32 P labelled fertilizer and five synthetic phosphates (dicalcium phosphate, octocalcium phosphate, iron phosphate, aluminium phosphate and apatite), which were used to simulate inorganic phosphates such as Ca 2 -P, Ca 8 -P, Fe P , Al-P and Ca 10 -P in calcareous soil, were applied to corn plants inoculating with and without vesicular-arbuscular (VA) mycorrhizal fungi in a calcareous soil. The results showed that VA mycorrhizal fungi and dicalcium phosphate, octocalcium phosphate, iron phosphate, aluminium phosphate promoted growth and increased phosphorus content of corn plant. The four synthetic phosphates except apatite had higher contributions to corn plant growth than VA mycorrhizal fungi. Contributions of fertilizer-P, soil-P and synthetic phosphates to phosphorus nutrition of corn plant were in order of synthetic phosphates (except apatite) > soil- P > fertilizer-P. Inoculating with VA mycorrhizal fungi increased the contribution of soil-P and decreased the contribution of synthetic phosphates, but did not affect the contribution of fertilizer-P

Control of lead solubility in soil contaminated with lead shot: Effect of soil pH

International Nuclear Information System (INIS)

Rooney, Corinne P.; McLaren, Ronald G.; Condron, Leo M.

2007-01-01

An incubation experiment was carried out to assess the rate of oxidation of Pb shot and subsequent transfer of Pb to the soil under a range of soil pH conditions. Lead shot corrosion was rapid, so that soil solution and fine earth ( 3 (CO 3 ) 2 (OH) 2 ), developed in crusts surrounding individual Pb pellets. However, irrespective of pH, Pb 2+ activities in the soil solutions, modelled using WHAM 6, were much lower than would be the case if they were controlled by the solubility of the dominant Pb compounds present in the Pb shot crust material. In contrast, modelling of soil solid-solution phase distribution of Pb, again using WHAM 6, suggested that, at least during the 24 months of the study, soil solution Pb concentrations were more likely to be controlled by sorption of Pb by the soil solid phase. - Sorption processes control Pb 2+ ion activity in soils contaminated with Pb shot

Effect of pH value of applied solution on radioiodine sorption by soils

International Nuclear Information System (INIS)

Szabova, T.

1976-01-01

Sorption of radioiodine by soils was followed under static conditions at different pH values of the initial solution in five soil types. Sorption of radioiodine by soils is affected by the amount of the organic mass and by the pH of solutions. With the same pH, soils containing a higher amount of the organic mass absorb more radioiodine. The highest sorption percentage of 131 I - for all pH values was found in meadow chernozem soil and the lowest in the rendzina and in carboniferous meadow soils. The highest sorption of 131 I - for degraded chernozem, meadow chernozem soils and brown soil was recorded at pH 5 and for carboniferous meadow soil and rendzina at pH 7. (author)

An approach for modeling the influence of wheel tractor loads and vibration frequencies on soil compaction

Science.gov (United States)

Verotti, M.; Servadio, P.; Belfiore, N. P.; Bergonzoli, S.

2012-04-01

Both soil compaction and ground vibration are forms of environmental degradation that may be understood in the context of the vehicle-soil interaction process considered (Hildebrand et al., 2008). The transit of tractors on agricultural soil is often the main cause of soil compaction increasing. As known, this can be a serious problems for tillage and sowing and therefore the influence of all the affecting factors have been extensively studied in the last decades in order to understand their impact on the biosystem. There are factors related to the climate, namely to the rainfalls and temperature, and many others. Hence, it is not simple to figure out a complete model for predicting an index of compaction, for a given situation. Soil compaction models are important tools for controlling soil compaction due to agricultural field traffic and they are potentially useful technique to provide information concerning correct soil management. By means of such models, strategies and recommendations for prevention of soil compaction may be developed and specific advice may be given to farmers and advisers. In order to predict field wheeled and tracked vehicle performance, some empirical methods, used for off-road vehicle, were applied by Servadio (2010) on agricultural soil. The empirical indexes included, besides the soil strength, the load carried by the tire or track, some technical characteristics of the tire or track of the vehicle (tire or track width, tire or track wheel diameter, unloaded tire section height, number of wheel station in one track, tire deflection, total length of the belt track, the track pitch) as well as the vehicle passes. They have been validated with the tests results of agricultural vehicles over a range of soil in central Italy. Among the parameters which affect soil compaction, the water content of the soil, the axle load and number of vehicle passes proved to be the most important ones. The present paper concerns mainly vehicle-soil

Influence of soil pH on the sorption of ionizable chemicals

DEFF Research Database (Denmark)

Franco, Antonio; Fu, Wenjing; Trapp, Stefan

2009-01-01

, the optimal pH to model dissociation was lower than the bulk soil pH. The knowledge of the soil pH allows calculation of the fractions of neutral and ionic molecules in the system, thus improving the existing regression for acids. The same approach was not successful with bases, for which the impact of p......The soil-water distribution coefficient of ionizable chemicals (K-d) depends on the soil acidity, mainly because the pH governs speciation. Using pH-specific K-d values normalized to organic carbon (K-OC) from the literature, a method was developed to estimate the K-OC of monovalent organic acids...

Numerical Analysis of Helical Pile-Soil Interaction under Compressive Loads

Science.gov (United States)

Polishchuk, A. I.; Maksimov, F. A.

2017-11-01

The results of the field tests of full-scale steel helical piles in clay soils intended for prefabricated temporary buildings foundations are presented in this article. The finite element modeling was used for the evaluation of stress distribution of the clay soil around helical piles. An approach of modeling of the screw-pile geometry has been proposed through the Finite Element Analysis. Steel helical piles with a length of 2.0 m, shaft diameter of 0.108 m and a blade diameter of 0.3 m were used in the experiments. The experiments have shown the efficiency of double-bladed helical piles in the clay soils compared to single-bladed piles. It has been experimentally established that the introduction of the second blade into the pile shaft provides an increase of the bearing capacity in clay soil up to 30% compared to a single-bladed helical pile with similar geometrical dimensions. The numerical results are compared with the measurements obtained by a large scale test and the bearing capacity has been estimated. It has been found that the model results fit the field results. For a double-bladed helical pile it was revealed that shear stresses upon pile loading are formed along the lateral surface forming a cylindrical failure surface.

Soil metal concentrations and vegetative assemblage structure in an urban brownfield

International Nuclear Information System (INIS)

Gallagher, Frank J.; Pechmann, Ildiko; Bogden, John D.; Grabosky, Jason; Weis, Peddrick

2008-01-01

Anthropogenic sources of toxic elements have had serious ecological and human health impacts. Analysis of the soil samples from a brownfield within Liberty State Park, Jersey City, NJ, USA, showed that arsenic, chromium, lead, zinc and vanadium exist at concentrations above those considered ambient for the area. Accumulation and translocation features were characterized for the dominant plant species of four vegetative assemblages. The trees Betula populifolia and Populus deltoides were found to be accumulating Zn in leaf tissue at extremely high levels. B. populifolia, P. deltoides and Rhus copallinum accumulated Cr primarily in the root tissue. A comparison of soil metal maps and vegetative assemblage maps indicates that areas of increasing total soil metal load were dominated by successional northern hardwoods while semi-emergent marshes consisting mostly of endemic species were restricted primarily to areas of low soil metal load. - The study yields insight into the impact of metal contaminates soils on vegetative assemblage structure and development

Soil pH management without lime, a strategy to reduce greenhouse gas emissions from cultivated soils

Science.gov (United States)

Nadeem, Shahid; Bakken, Lars; Reent Köster, Jan; Tore Mørkved, Pål; Simon, Nina; Dörsch, Peter

2015-04-01

For decades, agricultural scientists have searched for methods to reduce the climate forcing of food production by increasing carbon sequestration in the soil and reducing the emissions of nitrous oxide (N2O). The outcome of this research is depressingly meagre and the two targets appear incompatible: efforts to increase carbon sequestration appear to enhance the emissions of N2O. Currently there is a need to find alternative management strategies which may effectively reduce both the CO2 and N2O footprints of food production. Soil pH is a master variable in soil productivity and plays an important role in controlling the chemical and biological activity in soil. Recent investigations of the physiology of denitrification have provided compelling evidence that the emission of N2O declines with increasing pH within the range 5-7. Thus, by managing the soil pH at a near neutral level appears to be a feasible way to reduce N2O emissions. Such pH management has been a target in conventional agriculture for a long time, since a near-neutral pH is optimal for a majority of cultivated plants. The traditional way to counteract acidification of agricultural soils is to apply lime, which inevitably leads to emission of CO2. An alternative way to increase the soil pH is the use of mafic rock powders, which have been shown to counteract soil acidification, albeit with a slower reaction than lime. Here we report a newly established field trail in Norway, in which we compare the effects of lime and different mafic mineral and rock powders (olivine, different types of plagioclase) on CO2 and N2O emissions under natural agricultural conditions. Soil pH is measured on a monthly basis from all treatment plots. Greenhouse gas (GHG) emission measurements are carried out on a weekly basis using static chambers and an autonomous robot using fast box technique. Field results from the first winter (fallow) show immediate effect of lime on soil pH, and slower effects of the mafic rocks. The

The Influence of High Drug Loading in Xanthan Tablets and Media with Different Physiological pH and Ionic Strength on Swelling and Release.

Science.gov (United States)

Mikac, Urša; Sepe, Ana; Baumgartner, Saša; Kristl, Julijana

2016-03-07

The formation of a gel coat around xanthan (Xan) tablets, empty or loaded with pentoxifylline (PF), and its release in media differing in pH and ionic strength by NMR, MR imaging, and two release methods were studied. The T1 and T2 NMR relaxation times in gels depend predominantly on Xan concentration; the presence of PF has negligible influence on them. It is interesting that the matrix swelling is primarily regulated by Xan despite high drug loading (25%, 50%). The gastric pH and high ionic strength of the media do not influence the position of the penetration and swelling fronts but do affect the erosion front and gel thickness. The different release profiles obtained in mixing and nonmixing in vitro methods are the consequence of matrix hydration level and erosion at the surface. In water and in diluted acid medium with low ionic strength, the main release mechanism is erosion, whereas in other media (pH 1.2, μ ≥ 0.20 M), anomalous transport dominates as was found out by fitting of measured data with theoretical model. Besides the in vitro investigation that mimics gastric conditions, mathematical modeling makes the product development more successful.

[Cd Runoff Load and Soil Profile Movement After Implementation of Some Typical Contaminated Agricultural Soil Remediation Strategies].

Science.gov (United States)

Liu, Xiao-li; Zeng, Zhao-xia; Tie, Bai-qing; Chen, Qiu-wen; Wei, Xiang-dong

2016-02-15

Owing to the strong ability to immobilize and hyperaccumulate some toxic heavy metals in contaminated soils, the biochar, lime and such as hyperaccumulator ramie received increasing interests from crops and environment safety in recent years. Outdoor pot experiment was conducted to compare the impacts of lime and biochar addition in paddy rice treatment, hyperaccumulator ramie and ramie combined with EDTA of plant Phytoremediation methods on soil available Cd dynamics in rainfall runoff and the mobility along soil profile, under both natural acid precipitation and acid soil conditions. The results showed that, biochar addition at a 2% mass ratio application amount significantly increased soil pH, while ramie with EDTA application obviously decreased soil pH compared to ramie monoculture. Within the same rainfall events, water soluble Cd concentration in surface runoff of ramie treatments was significantly higher than those of waterlogged rice treatments, and Cd concentration in runoff was obviously increased after EDTA addition, whereas lime at a 0.3% mass ratio application amount as additive had no obvious impact on soil pH and Cd speciation change, which may be due to the low application amount. During the whole experimental period , water soluble Cd concentration of rainfall runoff in spring was higher than that in summer, showing the same seasonal characteristics in all treatments. Biochar addition could significantly decrease available Cd content in 0-20 cm soil layer and with certain preferable persistency effects, whereas EDTA addition treatment obviously increased available Cd of 0-20 cm soil layer compared to other treatments, and obvious Cd element activation phenomenon in 20-40 cm soil layer was observed after EDTA addition. In conclusion, lime and biochar as environmental and friendly alkaline Cd immobilization materials showed lower environment risk to surface and ground receiving water, but attention should be paid to phytoremediation enhanced with

Attentional capture under high perceptual load.

Science.gov (United States)

Cosman, Joshua D; Vecera, Shaun P

2010-12-01

Attentional capture by abrupt onsets can be modulated by several factors, including the complexity, or perceptual load, of a scene. We have recently demonstrated that observers are less likely to be captured by abruptly appearing, task-irrelevant stimuli when they perform a search that is high, as opposed to low, in perceptual load (Cosman & Vecera, 2009), consistent with perceptual load theory. However, recent results indicate that onset frequency can influence stimulus-driven capture, with infrequent onsets capturing attention more often than did frequent onsets. Importantly, in our previous task, an abrupt onset was present on every trial, and consequently, attentional capture might have been affected by both onset frequency and perceptual load. In the present experiment, we examined whether onset frequency influences attentional capture under conditions of high perceptual load. When onsets were presented frequently, we replicated our earlier results; attentional capture by onsets was modulated under conditions of high perceptual load. Importantly, however, when onsets were presented infrequently, we observed robust capture effects. These results conflict with a strong form of load theory and, instead, suggest that exposure to the elements of a task (e.g., abrupt onsets) combines with high perceptual load to modulate attentional capture by task-irrelevant information.

Benzo[a]pyrene in urban environments of eastern Moscow: pollution levels and critical loads

Science.gov (United States)

Kasimov, Nikolay S.; Kosheleva, Natalia E.; Nikiforova, Elena M.; Vlasov, Dmitry V.

2017-02-01

Polycyclic aromatic hydrocarbons (PAHs), particularly benzo[a]pyrene (BaP), are toxic compounds emitted from various anthropogenic sources. Understanding the BaP concentrations, dynamics and decomposition in soil is required to assess the critical loads of BaP in urban environments. This study is the first attempt to evaluate all major input and output components of benzo[a]pyrene (BaP) balance and to calculate the permissible load on the urban environment in different land-use zones in the Eastern district of Moscow. BaP contamination of the snow cover in the Eastern district of Moscow was related to daily BaP fallout from the atmosphere. In 2010, the mean content of the pollutant in the snow dust was 1942 ng g-1, whereas the average intensity of its fallout was 7.13 ng m-2 per day. Across the territory, BaP winter fallout intensities varied from 0.3 to 1100 ng m-2 per day. The average BaP content in the surface (0-10 cm) soil horizons was 409 ng g-1, which is 83 times higher than the local background value and 20 times higher than the maximum permissible concentration (MPC) accepted in Russia. The variations in soil and snow BaP concentrations among different land-use zones were examined. A significant contribution of BaP from the atmosphere to urban soils was identified. Based on the measurements of BaP atmospheric fallout and BaP reserves in the soils, the critical loads of BaP for the land-use zones in the Eastern district were calculated for different values of degradation intensity and different exposure times. It was established that at an annual degradation intensity of 1-10 %, ecologically safe BaP levels in the soils of all land-use zones, excluding the agricultural zone, will only be reached after many decades or centuries.

Methodologically controlled variations in laboratory and field pH measurements in waterlogged soils

DEFF Research Database (Denmark)

Elberling, Bo; Matthiesen, Henning

2007-01-01

artefacts is critical. But the study includes agricultural and forest soils for comparison. At a waterlogged site, Laboratory results were compared with three different field methods: calomel pH probes inserted in the soil from pits, pH measurements of soil solution extracted from the soil, and pH profiles...... using a solid-state pH electrode pushed into the soil from the surface. Comparisons between in situ and laboratory methods revealed differences of more than 1 pH unit. The content of dissolved ions in soil solution and field observations of O2 and CO2 concentrations were used in the speciation model...... PHREEQE in order to predict gas exchange processes. Changes in pH in soil solution following equilibrium in the laboratory could be explained mainly by CO2 degassing. Only soil pH measured in situ using either calomel or solid-state probes inserted directly into the soil was not affected by gas exchange...

Effect of ploughing depth and mechanical soil loading on soil physical properties, weed infestation, yield performance and grain quality in sole and intercrops of pea and oat in organic farming

OpenAIRE

Gronle, Annkathrin; Lux, Guido; Böhm, Herwart; Schmidtke, Knut; Wild, Melanie; Demmel, Markus; Brandhuber, Robert; Wilbois, Klaus-Peter; Heß, Jürgen

2015-01-01

The effect of ploughing depth and mechanical soil loading on the performance of pea sole crops, oat sole crops and pea–oat intercrops was investigated in field experiments under organic farming conditions at two sites in Germany in 2009 and 2010. The two ploughing depths were short-term shallow ploughing to a soil depth of 7–10 cm and deep ploughing to 25–30 cm. Wheel loads of 26 and 45 kN, which correspond to typical rear wheel loads of field machinery used during sowing operations, were com...

Next Day Subjective and Objective Recovery Indices Following Acute Low and High Training Loads in Academy Rugby Union Players

Directory of Open Access Journals (Sweden)

Mark R. Noon

2018-06-01

Full Text Available The aim of this study was to determine the sensitivity of selected subjective and objective monitoring assessments in detecting changes in group and individual responses to low and high load bouts of high intensity intermittent exercise. In a counterbalanced crossover design, Thirteen Academy Rugby Union players (mean ± SD: age: 18 ± 1 years performed a low load (15 min and a high load (90 min bout of high intensity intermittent exercise (Loughborough Intermittent Shuttle Test one week apart. Monitoring assessments were performed immediately prior to and 20 h following each trial. Subjective self-report Well-being Questionnaire (WQ items showed small to large deteriorations following the high load compared to low load (d = 0.4–1.5, p = 0.03–0.57. A very large increase in resting HR (HRrest (d = 2.1, p = 0.02, moderate decrease in heart rate variability (HRV indices (d = 0.7, p = 0.04 and d = 0.7, p = 0.01 for the natural logarithm of the standard deviation of R-R intervals (ln SDNN and the root square of the mean squared differences of successive R-R intervals (rMSSD, respectively and no change in countermovement jump (d = 0.0, p = 0.97 were evident following the high load compared to low load. Individual WQ responses revealed 7/9, 7/9, 6/9, 6/9, 5/9, 3/9 and 1/9 participants reported deteriorations in recovery, sleep quality, motivation, muscle soreness, fatigue, stress and appetite, respectively, following the high load compared to low load. Individual analysis indicated a negative response following the high load compared to low load in HRrest, ln SDNN and ln rMSSD for 4/6, 2/6 and 1/6 participants, respectively. Selected WQ items detected group and individual responses to high load and low load highlighting their potential utility. However, objective assessments lacked the sensitivity to detect small individual changes.

Retention of phosphorus in highly weathered soils under a lowland Amazonian forest ecosystem

Science.gov (United States)

M. E. McGroddy; W. L. Silver; Jr. de Oliveira; W. Z. de Mello; M. Keller

2008-01-01

The low available phosphorus (P) pools typical of highly weathered tropical forest soils are thought to result from a combination of export of phosphorus via erosion and leaching as well as chemical reactions resulting in physically and chemically protected P compounds. Despite the low apparent P availability, these soils support some of the highest terrestrial net...

Soil solution Zn and pH dynamics in non-rhizosphere soil and in the rhizosphere of Thlaspi caerulescens grown in a Zn/Cd-contaminated soil.

Science.gov (United States)

Luo, Y M; Christie, P; Baker, A J

2000-07-01

Temporal changes in soil solution properties and metal speciation were studied in non-rhizosphere soil and in the rhizosphere of the hyperaccumulator Thlaspi caerulescens J. & C. Presl (population from Prayon, Belgium) grown in a Zn- and Cd-contaminated soil. This paper focuses on soil solution Zn and pH dynamics during phytoextraction. The concentration of Zn in both non-rhizosphere and rhizosphere soil solutions decreased from 23 mg/l at the beginning to 2 mg/l at the end of the experiment (84 days after transplanting of seedlings), mainly due to chemical sorption. There was no significant difference in overall Zn concentration between the planted and the unplanted soil solutions (P > 0.05). Soil solution pH decreased initially and then increased slightly in both planted and unplanted soil zones. From 60 to 84 days after transplanting, the pH of the rhizosphere soil solution was higher than that of non-rhizosphere soil solution (P<0.05). Zn uptake by the hyperaccumulator plants was 8.8 mg per pot (each containing 1 kg oven-dry soil) on average. The data indicate that the potential of T. caerulescens to remove Zn from contaminated soil may not be related to acidification of the rhizosphere.

A method for apportionment of natural and anthropogenic contributions to heavy metal loadings in the surface soils across large-scale regions.

Science.gov (United States)

Hu, Yuanan; Cheng, Hefa

2016-07-01

Quantification of the contributions from anthropogenic sources to soil heavy metal loadings on regional scales is challenging because of the heterogeneity of soil parent materials and high variability of anthropogenic inputs, especially for the species that are primarily of lithogenic origin. To this end, we developed a novel method for apportioning the contributions of natural and anthropogenic sources by combining sequential extraction and stochastic modeling, and applied it to investigate the heavy metal pollution in the surface soils of the Pearl River Delta (PRD) in southern China. On the average, 45-86% of Zn, Cu, Pb, and Cd were present in the acid soluble, reducible, and oxidizable fractions of the surface soils, while only 12-24% of Ni, Cr, and As were partitioned in these fractions. The anthropogenic contributions to the heavy metals in the non-residual fractions, even the ones dominated by natural sources, could be identified and quantified by conditional inference trees. Combination of sequential extraction, Kriging interpolation, and stochastic modeling reveals that approximately 10, 39, 6.2, 28, 7.1, 15, and 46% of the As, Cd, Cr, Cu, Ni, Pb, and Zn, respectively, in the surface soils of the PRD were contributed by anthropogenic sources. These results were in general agreements with those obtained through subtraction of regional soil metal background from total loadings, and the soil metal inputs through atmospheric deposition as well. In the non-residual fractions of the surface soils, the anthropogenic contributions to As, Cd, Cr, Cu, Ni, Pb, and Zn, were 48, 42, 50, 51, 49, 24, and 70%, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

Screening and identification of p,p¢-DDT degrading soil isolates

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Vorasan Sobhon

2008-04-01

Full Text Available DDT is an organochlorine pesticide that can persist in the environment resulting in environmental problem with chronic effects on human and animal health. The determination of p,p¢-DDT in soil samples from 23 agricultural areas in Songkhla Province found DDT residue in the ranges of 0.17-9.84 ng/g soil. After repeated culturing in mineral salts-yeast extract medium (MSYM with an addition of 25 ppm p,p¢-DDT (DDT25, 167 morphologically different bacterial strains were isolated. Out of 167 isolates, only 5 strains showed p,p¢-DDT degrading ability as indicated by clear zone around the colony when grown on nutrient agar supplemented up to 100 ppm p,p¢-DDT. These 5 isolates include SB1A01, SB2A02, SB1A10, SB1A12 and SB1B05. Growth of these isolates in MSYM+DDT25 after 10 days indicated reductions of p,p¢-DDT by 30.5, 20.3, 37.4, 30.4 and 32.2%, respectively. Based on the morphological characteristics and 16S rDNA analysis, isolate SB1A10 which showed the highest degradation ability was found to be 99% identical (1360/1362 to Staphylococcus haemolyticus.

Dynamics of pH, Ferrum and Mangan, and Phosphorus on Newly Opened Paddy Soil having High Soil Organic Matter on Rice Growth

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Sukristyonubowo

2012-01-01

Full Text Available Research had been carried out at the Research and Soil Testing Laboratory and Greenhouse of Soil ResearchInstitute, Bogor using newly opened paddy soil from Pesisir Selatan districts, West Sumatra (one year old. Totaltreatments tested were 12 which were combination of farmer rate, NPK recommendation (½×; ¾×; 1½×, strawcompost (½×; ¾×; 1½×, and dolomite. The trial was conducted using a completely randomized design with threereplications. This research had been prepared in two units, one unit for observing plant response to nutrientmanagement and another unit for incubation trial with the same treatment placed in the greenhouse. Rice cultivarused was IR-42 in accordance to the preferred varieties of local farmers. The sampling method for measuring thesolubility of Fe2+ and Mn2+, as well as the availability of PO43- was by centrifuge 50 g mud samples from theincubation pots then separated clear extract using filter paper. The observation results on dynamics of pH, Fe2+,Mn2+ and PO4-3 mainly occured in 1 to 14 days after submerging (incubation. After 14 days soil reaction had reachedthermodynamic sequence of oxidation-reduction processes, the PO43- more available and pH of the soil reached thepeak. The optimum dose of NPK fertilizer obtained 0.875 NPK or equal to 175 kg of urea, 87.5 kg of SP-36 and 87.5 kgKCl ha-1. The highest number of hills achieved from straw compost treatment 1½ organic matter (OM or 3 tons withan increase of 20%. Application of ameliorant dolomite increased the number of tillers about 2-3%, but insignificantlydifferent with no dolomite treatment.

Numerical modeling of centrifuge cyclic lateral pile load experiments

Science.gov (United States)

Gerolymos, Nikos; Escoffier, Sandra; Gazetas, George; Garnier, Jacques

2009-03-01

To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussées. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimental p-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including: soil plastification at an early stage of loading, “pinching” behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. (1974) for sand, is also presented.

Mycorrhiza formation and nutrient concentration in leeks (¤Allium porrum¤) in relation to previous crop and cover crop management on high P soils

DEFF Research Database (Denmark)

Sørensen, J.N.; Larsen, J.; Jakobsen, I.

2005-01-01

An improved integration of mycorrhizas may increase the sustainability in plant production. Two strategies for increasing the soil inoculum potential of mycorrhizal fungi were investigated in field experiments with leeks: Pre-cropping with mycorrhizal main crops and pre-establishment of mycorrhizal......, increased the colonization of leek roots by mycorrhizal fungi. During early growth stages, this increase was 45-95% relative to no cover crop. However, cover cropping did not significantly increase nutrient concentration or growth. These variables were not influenced by the time of cover crop incorporation...... or tillage treatments. Differences in colonization, nutrient uptake and plant growth diminished during the growing period and at the final harvest date, the effects on plant production disappeared. High soil P level or high soil inoculum level was most likely responsible for the limited response of increased...

Impact of Acidification on Pollutants Fate and Soil Filtration Function

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Jarmila Makovniková

2014-12-01

Full Text Available The objective of this paper was to investigate the effects of simulated acid load on the fate of inorganic pollutants (Cd, Pb, soil sorption potential, soil filtration func-tion. We made use of a short-term acidification pot experiment with grown plant of spring barley cultivated at 4 different soil types (Fluvisol, Cambisol, Stagnosol, Podzol. The potential of soil filtration was evaluated according to the Eq.: [Soil filtration function]=[Potential of soil sorbents]+[Potential of total content of inor-ganic pollutants]. Potential of soil sorbents (PSS is defined by qualitative (pH, or-ganic matter quality - A400/600 and quantitative factors (carbon content-Cox, humus layer thickness-H according to the Eq.:[PSS]=F(pH+F(A465/665+F(Cox*F(H. Acid load significantly influenced soil sorption potential and thus affected increase in Cd and Pb mobility what was reflected in their transfer into the plants. Results of soil filtration function showed significant change of filtration function in Cambisol.

The behavior of P in tropical soils

International Nuclear Information System (INIS)

Bittencourt, V.C.; Zambello Junior, E.

1975-06-01

The experimental data showed that the whole P retention process depends on the levels and the reactivities of the iron oxides in the soils. It was established that the retention mechanism occurs in 2 or 3 stages and it is related to both the maximum adsorption and the absorbent capacity of the several soils as determined by the Langmuir and the Freundlich equations respectively. The final step of the P interaction which shows small rate constants is due to a diffusion of the phosphate ions from the oxide surface to the internal layers producing more stable iron-phosphate compounds

Soil biota response to amendment with biochar as P and K fertilizer

Science.gov (United States)

Winding, Anne; Imparato, Valentina; Santos, Susana; Hansen, Veronika; Haugaard-Nielsen, Henrik; Browne, Patrick; Hestbjerg Hansen, Lars; Henning Krogh, Paul; Johansen, Anders

2017-04-01

Thermal gasification converts biomass into a combustible gas at oxygen-poor conditions, the bi-product being biochar which can be used as soil amendment to increase pH, sequester carbon to mitigate climate change, and supply phosphate and potassium to crops; replacing chemical or other alternative organic fertilizers. Amending soil with biochar can support three soil functions: production of food, carbon sequestration, and biodiversity. This was tested in a field experiment with reduced-tillage agricultural management, where the effect of biochar amendment on soil ecosystem services, especially biodiversity and carbon sequestration were studied. The effects on soil microorganisms and fauna (protists and earthworms) were assessed with activity based assays and Next Generation Sequencing (NGS). Crops were alternating oil seed rape and winter wheat, and biochar was added annually for 3 years. The soil was a sandy loam soil with SOM content of ca. 5%. Earthworms and soil were sampled from field plots either left untreated, amended with straw or annually amended with either 6-8 t ha-1 or ca. 1 t ha-1 biochar. Soil was sampled from bulk soil and earthworm drilosphere. Earthworms had a priming effect on protist abundance and basal soil respiration. However, in biochar amended soil the protist abundance decreased in the drilosphere. Culturable bacteria and extracellular enzymatic activities were not significantly affected by earthworms. The abundance of only one earthworm species increased at high compared to low application levels of biochar, while still not differing from controls without biochar. Thus, no harmful effects were detected for earthworms. At the lower biochar amendment, significant changes were observed for the activity of a few selected enzymes related to biochar and also a relative increase in abundance of low abundant microorganisms was seen. At the high doses of biochar the abundance of protists increased compared to control. NGS analysis was more

Nestedness in Arbuscular Mycorrhizal Fungal Communities along Soil pH Gradients in Early Primary Succession: Acid-Tolerant Fungi Are pH Generalists.

Science.gov (United States)

Kawahara, Ai; An, Gi-Hong; Miyakawa, Sachie; Sonoda, Jun; Ezawa, Tatsuhiro

2016-01-01

Soil acidity is a major constraint on plant productivity. Arbuscular mycorrhizal (AM) fungi support plant colonization in acidic soil, but soil acidity also constrains fungal growth and diversity. Fungi in extreme environments generally evolve towards specialists, suggesting that AM fungi in acidic soil are acidic-soil specialists. In our previous surveys, however, some AM fungi detected in strongly acidic soils could also be detected in a soil with moderate pH, which raised a hypothesis that the fungi in acidic soils are pH generalists. To test the hypothesis, we conducted a pH-manipulation experiment and also analyzed AM fungal distribution along a pH gradient in the field using a synthesized dataset of the previous and recent surveys. Rhizosphere soils of the generalist plant Miscanthus sinensis were collected both from a neutral soil and an acidic soil, and M. sinensis seedlings were grown at three different pH. For the analysis of field communities, rhizosphere soils of M. sinensis were collected from six field sites across Japan, which covered a soil pH range of 3.0-7.4, and subjected to soil trap culture. AM fungal community compositions were determined based on LSU rDNA sequences. In the pH-manipulation experiment the acidification of medium had a significant impact on the compositions of the community from the neutral soil, but the neutralization of the medium had no effect on those of the community from the acidic soil. Furthermore, the communities in lower -pH soils were subsets of (nested in) those in higher-pH soils. In the field communities a significant nestedness pattern was observed along the pH gradient. These observations suggest that the fungi in strongly acidic soils are pH generalists that occur not only in acidic soil but also in wide ranges of soil pH. Nestedness in AM fungal community along pH gradients may have important implications for plant community resilience and early primary succession after disturbance in acidic soils.

Nestedness in Arbuscular Mycorrhizal Fungal Communities along Soil pH Gradients in Early Primary Succession: Acid-Tolerant Fungi Are pH Generalists

Science.gov (United States)

Kawahara, Ai; An, Gi-Hong; Miyakawa, Sachie; Sonoda, Jun

2016-01-01

Soil acidity is a major constraint on plant productivity. Arbuscular mycorrhizal (AM) fungi support plant colonization in acidic soil, but soil acidity also constrains fungal growth and diversity. Fungi in extreme environments generally evolve towards specialists, suggesting that AM fungi in acidic soil are acidic-soil specialists. In our previous surveys, however, some AM fungi detected in strongly acidic soils could also be detected in a soil with moderate pH, which raised a hypothesis that the fungi in acidic soils are pH generalists. To test the hypothesis, we conducted a pH-manipulation experiment and also analyzed AM fungal distribution along a pH gradient in the field using a synthesized dataset of the previous and recent surveys. Rhizosphere soils of the generalist plant Miscanthus sinensis were collected both from a neutral soil and an acidic soil, and M. sinensis seedlings were grown at three different pH. For the analysis of field communities, rhizosphere soils of M. sinensis were collected from six field sites across Japan, which covered a soil pH range of 3.0–7.4, and subjected to soil trap culture. AM fungal community compositions were determined based on LSU rDNA sequences. In the pH-manipulation experiment the acidification of medium had a significant impact on the compositions of the community from the neutral soil, but the neutralization of the medium had no effect on those of the community from the acidic soil. Furthermore, the communities in lower -pH soils were subsets of (nested in) those in higher-pH soils. In the field communities a significant nestedness pattern was observed along the pH gradient. These observations suggest that the fungi in strongly acidic soils are pH generalists that occur not only in acidic soil but also in wide ranges of soil pH. Nestedness in AM fungal community along pH gradients may have important implications for plant community resilience and early primary succession after disturbance in acidic soils. PMID

Adsorption-Desorption of Hexaconazole in Soils with Respect to Soil Properties, Temperature, and pH

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Maznah Zainol

2016-06-01

Full Text Available The effect of temperature and pH on adsorption-desorption of fungicide hexaconazole was studied in two Malaysian soil types; namely clay loam and sandy loam. The adsorption-desorption experiment was conducted using the batch equilibration technique and the residues of hexaconazole were analysed using the GC-ECD. The results showed that the adsorption-desorption isotherms of hexaconazole can be described with Freundlich equation. The Freundlich sorption coefficient (Kd values were positively correlated to the clay and organic matter content in the soils. Hexaconazole attained the equilibrium phase within 24 h in both soil types studied. The adsorption coefficient (Kd values obtained for clay loam soil and sandy loam soil were 2.54 mL/g and 2.27 mL/g, respectively, indicating that hexaconazole was weakly sorbed onto the soils due to the low organic content of the soils. Regarding thermodynamic parameters, the Gibb’s free energy change (ΔG analysis showed that hexaconazole adsorption onto soil was spontaneous and exothermic, plus it exhibited positive hysteresis. A strong correlation was observed between the adsorption of hexaconazole and pH of the soil solution. However, temperature was found to have no effect on the adsorption of hexaconazole onto the soils; for the range tested.

Pore-water chemistry explains zinc phytotoxicity in soil.

Science.gov (United States)

Kader, Mohammed; Lamb, Dane T; Correll, Ray; Megharaj, Mallavarapu; Naidu, Ravi

2015-12-01

Zinc (Zn) is a widespread soil contaminant arising from a numerous anthropogenic sources. However, adequately predicting toxicity of Zn to ecological receptors remains difficult due to the complexity of soil characteristics. In this study, we examined solid-solution partitioning using pore-water data and toxicity of Zn to cucumber (Cucumis sativus L.) in spiked soils. Pore-water effective concentration (ECx, x=10%, 20% and 50% reduction) values were negatively related to pH, indicating lower Zn pore water concentration were needed to cause phytotoxicity at high pH soils. Total dissolved zinc (Znpw) and free zinc (Zn(2+)) in soil-pore water successfully described 78% and 80.3% of the variation in relative growth (%) in the full dataset. When the complete data set was used (10 soils), the estimated EC50pw was 450 and 79.2 µM for Znpw and Zn(2+), respectively. Total added Zn, soil pore water pH (pHpw) and dissolve organic carbon (DOC) were the best predictors of Znpw and Zn(2+) in pore-water. The EC10 (total loading) values ranged from 179 to 5214 mg/kg, depending on soil type. Only pH measurements in soil were related to ECx total Zn data. The strongest relationship to ECx overall was pHca, although pHw and pHpw were in general related to Zn ECx. Similarly, when a solution-only model was used to predict Zn in shoot, DOC was negatively related to Zn in shoot, indicating a reduction in uptake/ translocation of Zn from solution with increasing DOC. Copyright © 2015 Elsevier Inc. All rights reserved.

Research on the Horizontal Displacement Coefficient of Soil Surrounding Pile in Layered Foundations by Considering the Soil Mass’s Longitudinal Continuity

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Yao Wen-Juan

2013-01-01

Full Text Available When utilizing the p-y curve to simulate the nonlinear characteristics of soil surrounding pile in layered foundations, due to having not taken into account the soil mass’s longitudinal continuity, the calculation deviation of horizontal displacement increases with the growth of a load. This paper adopted the layered elasticity system theory to consider the soil mass’s longitudinal continuity, as well as utilizing the research method for layered isotropic bodies, assuming that the horizontal resistance is evenly distributed around the perimeter of the pile's cross-section. Then an appropriate transfer matrix method of horizontal displacement coefficient for the soil surrounding pile in layered foundations was established. According to the calculation principle of finite element equivalent load, the horizontal displacement coefficient matrix was deduced as well as providing a corrected formula for the horizontal displacement of soil surrounding pile through the p-y curve method when the external load was increased. Following the established model, a program was created which was used for calculating and analyzing the horizontal displacement coefficient matrix of three-layered soil in order to verify this method’s validity and rationale. Where there is a relatively large discrepancy in the soil layers’ properties, this paper’s method is able to reflect the influence on the layered soil’s actual distributional difference as well as the nearby soil layers’ interaction.

The use of MP-AES for determination of plant available P in soil by DL method and distribution of soils into P status classes by DL, AL and Mehlich 3 methods.

Science.gov (United States)

Toomsoo, Avo; Jürgens, Meit; Kõlli, Raimo; Künnapas, Allan; Albre, Imbi; Tõnutare, Tõnu; Rodima, Ako

2017-04-01

Only small percentage of soil total phosphorus is easily exchangeable between solid and solution phase. Plants are able to assimilate P from environment only in the form of orthophosphate ions (H2PO4- and HPO42-) from soil solution. Deficit of P in soil solution prevents plant normal growth and decreases yield quantity and quality. The excess of P in soil solution causes the pollution of environment and eutrophication of water bodies. Therefore it is important to give to the plant producers the correct fertilization recommendations. Lot of analytical methods are developed for the determination of plant available P in soils. In the Baltic Sea region seven different soils' P analysis methods in use. Each method has its own gradation and often there is more than one gradation for the same method depending from agroecological conditions. For agricultural soils in Estonia there are soil P status gradations according to Mehlich 3, DL and AL methods. Phosphate content in soil can be determined by molybdate method Vis-spectrometrically. Very often for analysis of soils' P content also ICP-OES, ICP-MS and also MP-AES instrumental methods are used The aim of our work was to investigate the possibility of using MP-AES for determination of plant available P in soil by DL method and also to compare how the analysed soils are distributed to M3, AL and DL fertilizer requirement groups according to the P content.

CISM course on mechanical behaviour of soils under environmentally induced cyclic loads

CERN Document Server

Wood, David; Mechanical Behaviour of Soils Under Environmentally Induced Cyclic Loads

2012-01-01

The book gives a comprehensive description of the mechanical response of soils (granular and cohesive materials) under cyclic loading. It provides the geotechnical engineer with the theoretical and analytical tools necessary for the evaluation of settlements developng with time under cyclic, einvironmentally idncued loads (such as wave motion, wind actions, water table level variation) and their consequences for the serviceability and durability of structures such as the shallow or deep foundations used in offshore engineering, caisson beakwaters, ballast and airport pavements and also to interpret monitoring data, obtained from both natural and artificial slopes and earth embankments, for the purposes of risk assessment and mitigation.

Variation in pH optima of hydrolytic enzyme activities in tropical rain forest soils.

Science.gov (United States)

Turner, Benjamin L

2010-10-01

Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly among enzymes and soils. Enzymes were grouped into three classes based on their pH optima: (i) enzymes with acidic pH optima that were consistent among soils (cellobiohydrolase, β-xylanase, and arylsulfatase), (ii) enzymes with acidic pH optima that varied systematically with soil pH, with the most acidic pH optima in the most acidic soils (α-glucosidase, β-glucosidase, and N-acetyl-β-glucosaminidase), and (iii) enzymes with an optimum pH in either the acid range or the alkaline range depending on soil pH (phosphomonoesterase and phosphodiesterase). The optimum pH values of phosphomonoesterase were consistent among soils, being 4 to 5 for acid phosphomonoesterase and 10 to 11 for alkaline phosphomonoesterase. In contrast, the optimum pH for phosphodiesterase activity varied systematically with soil pH, with the most acidic pH optima (3.0) in the most acidic soils and the most alkaline pH optima (pH 10) in near-neutral soils. Arylsulfatase activity had a very acidic optimum pH in all soils (pH ≤3.0) irrespective of soil pH. The differences in pH optima may be linked to the origins of the enzymes and/or the degree of stabilization on solid surfaces. The results have important implications for the interpretation of hydrolytic enzyme assays using fluorogenic substrates.

Sterilization affects soil organic matter chemistry and bioaccumulation of spiked p,p'-DDE and anthracene by earthworms

Energy Technology Data Exchange (ETDEWEB)

Kelsey, Jason W., E-mail: kelsey@muhlenberg.ed [Program in Environmental Science and Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, PA 18104 (United States); Slizovskiy, Ilya B.; Peters, Richard D.; Melnick, Adam M. [Program in Environmental Science and Department of Chemistry, Muhlenberg College, 2400 Chew Street, Allentown, PA 18104 (United States)

2010-06-15

Laboratory experiments were conducted to assess the effects of soil sterilization on the bioavailability of spiked p,p'-DDE and anthracene to the earthworms Eisenia fetida and Lumbricus terrestris. Physical and chemical changes to soil organic matter (SOM) induced by sterilization were also studied. Uptake of both compounds added after soil was autoclaved or gamma irradiated increased for E. fetida. Sterilization had no effect on bioaccumulation of p,p'-DDE by L. terrestris, and anthracene uptake increased only in gamma-irradiated soils. Analyses by FT-IR and DSC indicate sterilization alters SOM chemistry and may reduce pollutant sorption. Chemical changes to SOM were tentatively linked to changes in bioaccumulation, although the effects were compound and species specific. Artifacts produced by sterilization could lead to inaccurate risk assessments of contaminated sites if assumptions derived from studies carried out in sterilized soil are used. Ultimately, knowledge of SOM chemistry could aid predictions of bioaccumulation of organic pollutants. - Soil sterilization affects soil organic matter chemistry and pollutant bioaccumulation.

pH controls over methanogenesis and iron reduction along soil depth profile in Arctic tundra

Science.gov (United States)

Zheng, J.; Gu, B.; Wullschleger, S. D.; Graham, D. E.

2017-12-01

Increasing soil temperature in the Arctic is expected to accelerate rates of soil organic matter decomposition. However, the magnitude of this impact is uncertain due to the many physical, chemical, and biological processes that control the decomposition pathways. Varying soil redox conditions present a key control over pathways of organic matter decomposition by diverting the flow of reductants among different electron accepting processes and further driving acid-base reactions that alter soil pH. In this study we investigated the pH controls over anaerobic carbon mineralization, methanogenesis, Fe(III) reduction and the interplay between these processes across a range of pH and redox conditions. pH manipulation experiments were conducted by incubating soils representing organic, mineral, cryoturbated transitional layers and permafrost. In the experiments we sought to understand (1) if methanogenesis or Fe(III) reduction had similar pH optima; (2) if this pH response also occurs at `upstream' fermentation process; and (3) if pH alters organo-mineral association or organic matter sorption and desorption and its availability for microbial degradation. Our preliminary results suggest that the common bell-shaped pH response curve provides a good fit for both Fe(III) reduction and methanogenesis, with optimum pH at 6.0-7.0. Exceptions to this were found in transitional layer where methanogenesis rates positively correlated with increasing pH, with maximum rates measured at pH 8.5. It is likely that the transitional layer harbors distinct groups of methanogens that prefer a high pH. Variations in the optimum pH of Fe(III) reduction and methanogenesis may play a significant role in regulating organic matter decomposition pathways and thus greenhouse gas production in thawing soils. These results support biogeochemical modeling efforts to accurately simulate organic matter decomposition under changing redox and pH conditions.

Acinetobacter calcoaceticus CSY-P13 Mitigates Stress of Ferulic and p-Hydroxybenzoic Acids in Cucumber by Affecting Antioxidant Enzyme Activity and Soil Bacterial Community

Directory of Open Access Journals (Sweden)

Fenghui Wu

2018-06-01

Full Text Available Ferulic acid (FA and p-hydroxybenzoic acid (PHBA are main phenolic compounds accumulated in rhizosphere of continuously cropped cucumber, causing stress in plants. Microbial degradation of a mixture of FA and PHBA is not well understood in soil. We isolated a strain CSY-P13 of Acinetobacter calcoaceticus, inoculated it into soil to protect cucumber from FA and PHBA stress, and explored a mechanism underlying the protection. CSY-P13 effectively degraded a mixture of FA and PHBA in culture solution under conditions of 39.37°C, pH 6.97, and 21.59 g L-1 potassium dihydrogen phosphate, giving rise to 4-vinyl guaiacol, vanillin, vanillic acid, and protocatechuic acid. During FA and PHBA degradation, activities of superoxide dismutase (SOD, catalase, ascorbate peroxidase, and dehydroascorbate reductase in CSY-P13 were induced. Inoculated into cucumber-planted soil containing 220 μg g-1 mixture of FA and PHBA, CSY-P13 degraded FA and PHBA in soil, increased plant height, and decreased malonaldehyde, superoxide radical, and hydrogen peroxide levels in leaves. CSY-P13 also enhanced SOD, guaiacol peroxidase, catalase, glutathione peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase activities; increased ascorbate and glutathione contents; and elevated transcript levels of copper/zinc SOD, manganese SOD, and catalase in leaves under FA and PHBA. Moreover, CSY-P13 increased phosphatase, catalase, urease, and sucrase activities and changed bacterial richness, diversity, and community composition by high throughput sequencing in cucumber-planted soil supplemented with the mixture of FA and PHBA. So CSY-P13 degrades the mixture of FA and PHBA in soil and mitigates stress from the two phenolic compounds in cucumber by activating antioxidant enzymes, changing soil bacterial community, and inducing soil enzymes.

Influence of soil-extractable aluminium and pH on the uptake of aluminium from soil into the soybean plant (Glycine max).

Science.gov (United States)

Dong, D; Thornton, I; Ramsey, M H

1993-09-01

The effects of soil pH and other soil properties on the uptake of AI by soybean plants have been investigated in a greenhouse experiment. Six soils were compared that were developed over six contrasting bedrock types ranging widely in their AI content and other chemical and physical characteristics, namely Oxford Clay, Chalk, Lower Lias Clay, Devonian Shale, Granite and Lower Greensand. Soil pH varied naturally between soil types and each soil was also amended to give two other pH levels using elemental sulphur and/or calcium carbonate. AI concentrations in various parts of the soybean plants were determined by ICP-AES after acid digestion. The AI solubility in the soils and hence its availability to the plants was estimated using a number of different reagents designed to extract different forms of AI.The AI concentration measured in the soybean leaves was found to be predicted most accurately by the 'available' AI extracted from soils by 0.02 M CaCl2. The relationship appears to the linear, with a correlation coefficient of 0.97 (p <0.01). The AI content of the leaves increases with decreasing soil pH. The relationship is non-linear with a marked increase in leaf AI for soils with pH <4.4. The amounts of 'plant-available' AI in the soils extracted with 0.02 M CaCl2 was much less than that extracted with 0.05 M EDTA, although both increased markedly with decreasing soil pH. The amount of AI measured in the soybean plants was directly related to both the 'available' forms of AI in the soils, and also to the pH of the soils. Soil pH was identified as a major factor that controls the uptake of Al from soil into the soybean plant.

Numerical Simulation of Hysteretic Live Load Effect in a Soil-Steel Bridge

Directory of Open Access Journals (Sweden)

Sobótka Maciej

2014-03-01

Full Text Available The paper presents numerical simulation of hysteretic live load effect in a soil-steel bridge. The effect was originally identified experimentally by Machelski [1], [2]. The truck was crossing the bridge one way and the other in the full-scale test performed. At the same time, displacements and stress in the shell were measured. The major conclusion from the research was that the measured quantities formed hysteretic loops. A numerical simulation of that effect is addressed in the present work. The analysis was performed using Flac finite difference code. The methodology of solving the mechanical problems implemented in Flac enables us to solve the problem concerning a sequence of load and non-linear mechanical behaviour of the structure. The numerical model incorporates linear elastic constitutive relations for the soil backfill, for the steel shell and the sheet piles, being a flexible substructure for the shell. Contact zone between the shell and the soil backfill is assumed to reflect elastic-plastic constitutive model. Maximum shear stress in contact zone is limited by the Coulomb condition. The plastic flow rule is described by dilation angle ψ = 0. The obtained results of numerical analysis are in fair agreement with the experimental evidence. The primary finding from the performed simulation is that the slip in the interface can be considered an explanation of the hysteresis occurrence in the charts of displacement and stress in the shell.

Effect of the pH on the radiocesium adsorption in tropical soils

International Nuclear Information System (INIS)

Roque, Mario Lucio; Boaretto, Antonio E.; Moniz, Antonio C; Smolders, Erik E. T.

2002-01-01

The objective was to demonstrate that the pH dependent charges are specific change sites for radiocesium. Clay minerals occurrence in superficial samples of eight tropical soils was analyzed by X-Ray diffractometry. The variation of superficial charge of these soils were quantify by potentiometric titration in a range from 3 to 8 pH values. The results of radiocesium interception potential showed the presence of specific sites of adsorption of this radionuclide for all the soils. The variation of radiocesium adsorption for all soils was quantified in a pH defined range. The increase on the pH values caused increase on the radiocesium adsorption by the soils and a consequent decrease in the radiocesium activity in the equilibrium solution. The soil with predominance of the 2:1 clay minerals showed higher radiocesium adsorption than the soils with 1:1 clay minerals or iron and aluminum oxides. The increase on the negative charge in consequence of pH increase caused increase on radiocesium adsorption. The correction of soil acidity with lime by increasing the specific sites charge for radiocesium and decreasing the radionuclide activity in soil solution may cause decrease on the transference of radiocesium from soil to plant. (author)

[Variation characteristics of farmland soil pH in the past 30 years of Enshi Autonomous Prefecture, Hubei, China].

Science.gov (United States)

Hu, Min; Xiang, Yong Sheng; Zhang, Zhi; Cong, Ri Huan; Huang, Fei Yue; Zhang, Jun Qiang; Shang, Li Li; Lu, Jian Wei

2017-04-18

In order to explore temporal-spatial variability of farmland soil pH at Enshi Antonomous Prefecture, Hubei, China, soil pH during the past three decades was analyzed, using the datasets of the Second National Soil Survey (1980-1983) and the Cultivated Land Quality Evaluation (2010-2013). The natural and human factors inducing the change of soil pH were evaluated to provide theoretical guidance for further soil acidification management. Results showed that acidic soil (i.e., pH＜6.5) and neutral and alkaline soil (i.e., pH 6.5-8.5) were accounted for 98.4% and 1.6% in the farmland during the period of 2010-2013, respectively. The ratio increased 61.4% for the acidic soil but decreased 61.2% for the neutral and alkaline soil as compared with the period of 1980-1983. In addition, there was no alkaline soil (pH>8.5) in the region in 2010-2013. According to the dataset of the Second National Soil Survey (1980-1983), acidic soil was mainly distributed at Laifeng, Lichuan, Xuanen and Xianfeng counties, with the area ratio of 74.4%, 63.5%, 61.3% and 60.7%, respectively. For the period of 2010-2013, the ratio of acidic soil enhanced widely which was above 96% for each county. At Enshi Autonomous Prefecture, farmland soil showed an obvious acidification trend during the past three decades, with spatial variation of higher in the eastern part and lower in the western part of the region. Furthermore, soil pH decline occurred among different land use types in different areas. Overall, farmland soil pH declined 0.90 on average, with 1.14 decrease for upland and 0.87 for paddy soil, respectively. Clearly, upland soil acidification was severe than paddy soil. Factors related to soil acidification in the Enshi Autonomous Prefecture were mainly human factors such as unreasonable fertilizer combination, fertilizer ratio change, and more base cations taking away by high crop yield.

Acid-base status of soils in groundwater discharge zones — relation to surface water acidification

Science.gov (United States)

Norrström, Ann Catrine

1995-08-01

Critical load calculations have suggested that groundwater at depth of 2 m in Sweden is very sensitive to acid load. As environmental isotope studies have shown that most of the runoff in streams has passed through the soil, there is a risk in the near future of accelerated acidification of surface waters. To assess the importance of the last soil horizon of contact before discharge, the upper 0-0.2m of soils in seven discharge zones were analysed for pools of base cations, acidity and base saturation. The sites were about 3-4 m 2 in size and selected from two catchments exposed to different levels of acid deposition. The soils in the seven sites had high concentrations of exchangeable base cations and consequently high base saturation. The high correlation ( r2 = 0.74) between base saturation in the soils of the discharge zones and mean pH of the runoff waters suggested that the discharge zone is important for surface water acidification. The high pool of exchangeable base cations will buffer initially against the acid load. As the cation exchange capacity (meq dm -3) and base saturation were lower in the sites from the catchment receiving lower deposition, these streams may be more vulnerable to acidification in the near future. The high concentration of base cations in non-exchangeable fractions may also buffer against acidification as it is likely that some of these pools will become exchangeable with time.

Effectiveness of Direct Application of Phosphate Rock in Upland Acid Inceptisols Soils on Available-P and Maize Yield

Directory of Open Access Journals (Sweden)

Nurjaya

2013-03-01

Full Text Available Source of P fertilizer which is used by farmers in upland acid soils area is generally acidulated phosphate rock (PR,such as tripel super phosphate (TSP, super phosphate 36% P2O5 (SP-36, as well as partial acidulated phosphate rock (PAPR which contain 10-30% P2O5. Their effectiveness, however, varies and depends on the soil and planttypes. Phosphate rock fertilizers have a high prospects for acid soils because its effectiveness equals to the SP-36,cheaper, slow release, and its application can also leave the residual P in the soil that available for plants for next few seasons. Field experiment aimed to study the effectiveness of direct application of PR at upland acid soils and its effect on soil available-P as well as maize (Zea mays L. yield was conducted in Acid Inceptisols of Ciampea,Bogorin wet season years 2008/2009. The experiment was arranged by a Randomized Completely Block Design with 3 replications. Maize of P-12 variety was used as a plant indicator. The treatment consisted of 6 levels of phosphate rock: 0, 20, 30, 40, 50, and 60 kg P ha-1, as well as one level of SP-36 40 kg P ha-1 as standard fertilizer. In addition, urea of 300 kg ha-1 and KCl of 100 kg ha-1 were used as basal fertilization. The result showed that the application of PRin the amount ranging from 20 to 60 kg P ha-1 increased total-P and available-P, and pH, decreased exchangeable Al in the soils as well as increased maize straw and grain. Phosphate rock application at 40 kg P ha-1 level was equally effective as SP-36 in the tested soils. Critical level of soil P for maize grown in the soil was 675 and 5.00 mg P2O5 kg-1 extracted with HCl 25% and Bray I, respectively. The requirement of P for maize grown in the soil to achieve maximum profit was 38 kg P ha-1 and 17.5 kg P ha-1 or equivalent to PR of 583 and 268 kg ha-1 in low (soil P critical level soil P status, respectively.

Phosphorus content as a function of soil aggregate size and paddy cultivation in highly weathered soils.

Science.gov (United States)

Li, Baozhen; Ge, Tida; Xiao, Heai; Zhu, Zhenke; Li, Yong; Shibistova, Olga; Liu, Shoulong; Wu, Jinshui; Inubushi, Kazuyuki; Guggenberger, Georg

2016-04-01

Red soils are the major land resource in subtropical and tropical areas and are characterized by low phosphorus (P) availability. To assess the availability of P for plants and the potential stability of P in soil, two pairs of subtropical red soil samples from a paddy field and an adjacent uncultivated upland were collected from Hunan Province, China. Analysis of total P and Olsen P and sequential extraction was used to determine the inorganic and organic P fractions in different aggregate size classes. Our results showed that the soil under paddy cultivation had lower proportions of small aggregates and higher proportions of large aggregates than those from the uncultivated upland soil. The portion of >2-mm-sized aggregates increased by 31 and 20 % at Taoyuan and Guiyang, respectively. The total P and Olsen P contents were 50-150 and 50-300 % higher, respectively, in the paddy soil than those in the upland soil. Higher inorganic and organic P fractions tended to be enriched in both the smallest and largest aggregate size classes compared to the middle size class (0.02-0.2 mm). Furthermore, the proportion of P fractions was higher in smaller aggregate sizes (2 mm). In conclusion, soils under paddy cultivation displayed improved soil aggregate structure, altered distribution patterns of P fractions in different aggregate size classes, and to some extent had enhanced labile P pools.

pH dominates variation in tropical soil archaeal diversity and community structure.

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Tripathi, Binu M; Kim, Mincheol; Lai-Hoe, Ang; Shukor, Nor A A; Rahim, Raha A; Go, Rusea; Adams, Jonathan M

2013-11-01

Little is known of the factors influencing soil archaeal community diversity and composition in the tropics. We sampled soils across a range of forest and nonforest environments in the equatorial tropics of Malaysia, covering a wide range of pH values. DNA was PCR-amplified for the V1-V3 region of the 16S rRNA gene, and 454-pyrosequenced. Soil pH was the best predictor of diversity and community composition of Archaea, being a stronger predictor than land use. Archaeal OTU richness was highest in the most acidic soils. Overall archaeal abundance in tropical soils (determined by qPCR) also decreased at higher pH. This contrasts with the opposite trend previously found in temperate soils. Thaumarcheota group 1.1b was more abundant in alkaline soils, whereas group 1.1c was only detected in acidic soils. These results parallel those found in previous studies in cooler climates, emphasizing niche conservatism among broad archaeal groups. Among the most abundant operational taxonomic units (OTUs), there was clear evidence of niche partitioning by pH. No individual OTU occurred across the entire range of pH values. Overall, the results of this study show that pH plays a major role in structuring tropical soil archaeal communities. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

[Spatiotemporal variation of soil pH in Guangdong Province of China in past 30 years].

Science.gov (United States)

Guo, Zhi-Xing; Wang, Jing; Chai, Min; Chen, Ze-Peng; Zhan, Zhen-Shou; Zheng, Wu-Ping; Wei, Xiu-Guo

2011-02-01

Based on the 1980s' soil inventory data and the 2002-2007 soil pH data of Guangdong Province, the spatiotemporal variation of soil pH in the Province in past 30 years was studied. In the study period, the spatial distribution pattern of soil pH in the Province had less change (mainly acidic), except that in Pearl River Delta and parts of Qingyuan and Shaoguan (weak alkaline). The overall variation of soil pH was represented as acidification, with the average pH value changed from 5.70 to 5.44. Among the soil types in the Province, alluvial soil had an increased pH, lateritic red soil, paddy soil, and red soil had a large decrement of pH value, and lime soil was most obvious in the decrease of pH value and its area percentage. The soil acidification was mainly induced by soil characteristics, some natural factors such as acid rain, and human factors such as unreasonable fertilization and urbanization. In addition, industrialization and mining increased the soil pH in some areas.

Risk assessment of soil compaction in Walloon Region (Belgium)

Science.gov (United States)

Charlotte, Rosiere; Marie-France, Destain; Jean-Claude, Verbrugge

2010-05-01

) was used to estimate the distribution of the vertical stresses z in the soil. Comparison was performed between z and Pc. The following data simulated the passage of a beet harvester machine (mass: 23 580 kg; load: 18 000 kg) in a silty soil located in Hesbaye and classified as Aba (Sirjacobs et al., 2000). The passage of the machine would create a Pc of around 100 kPa at 30 cm depth, while the stress induced by the machine would reach 240 kPa. In the field borders, where more vehicle traffic was usually observed and where the soil was over consolidated, Pc would reach 180 kPa, while z would be 220 kPa. In both cases, the risk of compaction created by the passage of the machine would be high. - Lebert, M. and Horn, R. (1991). A method to predict the mechanical strength of agricultural soils. Soil & Tillage Res. 19, 275-286. - Keller T., Défossez P., Weisskopf P., Arvidson J., Richard G. (2007). SoilFlex : A model for prediction of soil stresses and soil compaction due to agricultural field traffic including a synthesis of analytical approaches. Soil & Tillage Research 93, 391-411. - Sirjacobs D., Hanquet B., Lebeau F., Destain M.-F. (2002). On-line mechanical resistance mapping and correlation with soil physical properties for precision agriculture. Soil and Tillage Research, 64, 231-242.

Water balance creates a threshold in soil pH at the global scale

Science.gov (United States)

Slessarev, E. W.; Lin, Y.; Bingham, N. L.; Johnson, J. E.; Dai, Y.; Schimel, J. P.; Chadwick, O. A.

2016-12-01

Soil pH regulates the capacity of soils to store and supply nutrients, and thus contributes substantially to controlling productivity in terrestrial ecosystems. However, soil pH is not an independent regulator of soil fertility—rather, it is ultimately controlled by environmental forcing. In particular, small changes in water balance cause a steep transition from alkaline to acid soils across natural climate gradients. Although the processes governing this threshold in soil pH are well understood, the threshold has not been quantified at the global scale, where the influence of climate may be confounded by the effects of topography and mineralogy. Here we evaluate the global relationship between water balance and soil pH by extracting a spatially random sample (n = 20,000) from an extensive compilation of 60,291 soil pH measurements. We show that there is an abrupt transition from alkaline to acid soil pH that occurs at the point where mean annual precipitation begins to exceed mean annual potential evapotranspiration. We evaluate deviations from this global pattern, showing that they may result from seasonality, climate history, erosion and mineralogy. These results demonstrate that climate creates a nonlinear pattern in soil solution chemistry at the global scale; they also reveal conditions under which soils maintain pH out of equilibrium with modern climate.

Load Balancing Scheme on the Basis of Huffman Coding for P2P Information Retrieval

Science.gov (United States)

Kurasawa, Hisashi; Takasu, Atsuhiro; Adachi, Jun

Although a distributed index on a distributed hash table (DHT) enables efficient document query processing in Peer-to-Peer information retrieval (P2P IR), the index costs a lot to construct and it tends to be an unfair management because of the unbalanced term frequency distribution. We devised a new distributed index, named Huffman-DHT, for P2P IR. The new index uses an algorithm similar to Huffman coding with a modification to the DHT structure based on the term distribution. In a Huffman-DHT, a frequent term is assigned to a short ID and allocated a large space in the node ID space in DHT. Throuth ID management, the Huffman-DHT balances the index registration accesses among peers and reduces load concentrations. Huffman-DHT is the first approach to adapt concepts of coding theory and term frequency distribution to load balancing. We evaluated this approach in experiments using a document collection and assessed its load balancing capabilities in P2P IR. The experimental results indicated that it is most effective when the P2P system consists of about 30, 000 nodes and contains many documents. Moreover, we proved that we can construct a Huffman-DHT easily by estimating the probability distribution of the term occurrence from a small number of sample documents.

Spatial variability of soil carbon, pH, available phosphorous and potassium in organic farm located in Mediterranean Croatia

Science.gov (United States)

Bogunović, Igor; Pereira, Paulo; Šeput, Miranda

2016-04-01

Soil organic carbon (SOC), pH, available phosphorus (P), and potassium (K) are some of the most important factors to soil fertility. These soil parameters are highly variable in space and time, with implications to crop production. The aim of this work is study the spatial variability of SOC, pH, P and K in an organic farm located in river Rasa valley (Croatia). A regular grid (100 x 100 m) was designed and 182 samples were collected on Silty Clay Loam soil. P, K and SOC showed moderate heterogeneity with coefficient of variation (CV) of 21.6%, 32.8% and 51.9%, respectively. Soil pH record low spatial variability with CV of 1.5%. Soil pH, P and SOC did not follow normal distribution. Only after a Box-Cox transformation, data respected the normality requirements. Directional exponential models were the best fitted and used to describe spatial autocorrelation. Soil pH, P and SOC showed strong spatial dependence with nugget to sill ratio with 13.78%, 0.00% and 20.29%, respectively. Only K recorded moderate spatial dependence. Semivariogram ranges indicate that future sampling interval could be 150 - 200 m in order to reduce sampling costs. Fourteen different interpolation models for mapping soil properties were tested. The method with lowest Root Mean Square Error was the most appropriated to map the variable. The results showed that radial basis function models (Spline with Tension and Completely Regularized Spline) for P and K were the best predictors, while Thin Plate Spline and inverse distance weighting models were the least accurate. The best interpolator for pH and SOC was the local polynomial with the power of 1, while the least accurate were Thin Plate Spline. According to soil nutrient maps investigated area record very rich supply with K while P supply was insufficient on largest part of area. Soil pH maps showed mostly neutral reaction while individual parts of alkaline soil indicate the possibility of penetration of seawater and salt accumulation in the

Wood ash application increases pH but does not harm the soil mesofauna

DEFF Research Database (Denmark)

Qin, Jiayi; Hovmand, Mads Frederik; Ekelund, Flemming

2017-01-01

Application of bioash from biofuel combustion to soil supports nutrient recycling, but may have unwanted and detrimental ecotoxicological side-effects, as the ash is a complex mixture of compounds that could affect soil invertebrates directly or through changes in their food or habitat conditions...... is the likely cause of effects while high pH and heavy metals is of minor importance.......Application of bioash from biofuel combustion to soil supports nutrient recycling, but may have unwanted and detrimental ecotoxicological side-effects, as the ash is a complex mixture of compounds that could affect soil invertebrates directly or through changes in their food or habitat conditions....... To examine this, we performed laboratory toxicity studies of the effects of wood-ash added to an agricultural soil and the organic horizon of a coniferous plantation soil with the detrivore soil collembolans Folsomia candida and Onychiurus yodai, the gamasid predaceous mite Hypoaspis aculeifer...

Soil compaction: Evaluation of stress transmission and resulting soil structure

Science.gov (United States)

Naveed, Muhammad; Schjønning, Per; Keller, Thomas; Lamande, Mathieu

2016-04-01

Accurate estimation of stress transmission and resultant deformation in soil profiles is a prerequisite for the development of predictive models and decision support tools for preventing soil compaction. Numerous studies have been carried out on the effects of soil compaction, whilst relatively few studies have focused on the cause (mode of stress transmission in the soil). We have coupled both cause and effects together in the present study by carrying out partially confined compression tests on (1) wet aggregates, (2) air dry aggregates, and (3) intact soils to quantify stress transmission and compaction-resulted soil structure at the same time. Stress transmission was quantified using both X-ray CT and Tactilus sensor mat, and soil-pore structure was quantified using X-ray CT. Our results imply that stress transmission through soil highly depends on the magnitude of applied load and aggregate strength. As soon as the applied load is lower than the aggregate strength, the mode of stress transmission is discrete as stresses were mainly transmitted through chain of aggregates. With increasing applied load soil aggregates start deforming that transformed heterogeneous soil into homogenous, as a result stress transmission mode was shifted from discrete towards more like a continuum. Continuum-like stress transmission mode was better simulated with Boussinesq (1885) model based on theory of elasticity compared to discrete. The soil-pore structure was greatly affected by increasing applied stresses. Total porosity was reduced 5-16% and macroporosity 50-85% at 620 kPa applied stress for the intact soils. Similarly, significant changes in the morphological indices of the macropore space were also observed with increasing applied stresses.

Multiple assessment of the soil cover in the area of natural monuments Tra-Tau and Yurak-Tau monadnocks under conditions of technogenic loads

Science.gov (United States)

Gabbasova, I. M.; Suleymanov, R. R.; Khabirov, I. K.; Komissarov, M. A.; Garipov, T. T.; Sidorova, L. V.; Nazyrova, F. I.

2014-02-01

The soil cover of Tra-Tau and Yurak-Tau shikhans (monadnocks) has been examined. Leached and typical medium-deep chernozems are developed on colluvial fans on the footslopes and on the lower parts of slopes, whereas typical calcareous thin slightly and moderately gravelly chernozems are developed on the upper and medium parts of slopes. The leached and typical chernozems of the footslopes correspond to zonal soils of the adjacent plain areas, though they have some specific features related to the local topographic conditions. These soils are somewhat thinner than plain chernozems and are characterized by the perfect granular water-stable structure, the high content of humus of the humate type, the high content of exchangeable cations, strong acid-base buffering, and high enzymatic activity. These features predetermine their high tolerance towards technogenic impacts. The concentrations of highly hazardous substances of the first toxicity class (mercury, arsenic, lead, and cadmium) and of moderately hazardous substances of the second toxicity class (copper, zinc, and nickel), as well as the concentrations of low-hazardous elements (manganese and iron) in these soils do not exceed provisional maximum permissible concentrations of these substances in soils irrespectively of the slope aspect. No changes in the physicochemical and biological properties of the soils under the impact of technogenic loads from Sterlitamak industrial center have been identified.

Using a toxicokinetics approach to explain the effect of soil pH on cadmium bioavailability to Folsomia candida

International Nuclear Information System (INIS)

Ardestani, Masoud M.; Gestel, Cornelis A.M. van

2013-01-01

The aim of this study was to improve our understanding of metal bioavailability in soil by linking the biotic ligand approach with toxicokinetics modelling. We determined cadmium bioaccumulation kinetics in Folsomia candida (Collembola) as a function of soil pH. Animals were exposed for 21 days to LUFA 2.2 soil at 5 or 20 μg Cd g −1 dry soil followed by 21 days elimination in clean soil. Internal cadmium concentrations were modelled using a first-order one-compartment model, relating uptake rate constants (k 1 ) to total soil, water or 0.01 M CaCl 2 extractable and porewater concentrations. Based on total soil concentrations, k 1 was independent of soil pH while it strongly increased with increasing pH based on porewater concentrations explaining the reduced competition of H + ions making cadmium more bioavailable in pore water at high pH. This shows that the principles of biotic ligand modelling are applicable to predict cadmium accumulation kinetics in soil-living invertebrates. -- Highlights: •Cadmium uptake and elimination in Folsomia candida were investigated. •Animals were exposed to LUFA 2.2 soil at different pH levels. •Langmuir isotherms were used to describe interaction of Ca and protons with Cd. •pH was the main factor affecting Cd toxicokinetics when pore water was considered. -- Integrating bioaccumulation kinetics with a BLM approach provides novel insights into the bioavailability of cadmium to springtails in soil

[Effects of phosphorus sources on phosphorus fractions in rhizosphere soil of wild barley genotypes with high phosphorus utilization efficiency].

Science.gov (United States)

Cai, Qiu-Yan; Zhang, Xi-Zhou; Li, Ting-Xuan; Chen, Guang-Deng

2014-11-01

High P-efficiency (IS-22-30, IS-22-25) and low P-efficiency (IS-07-07) wild barley cultivars were chosen to evaluate characteristics of phosphorus uptake and utilization, and properties of phosphorus fractions in rhizosphere and non-rhizosphere in a pot experiment with 0 (CK) and 30 mg P · kg(-1) supplied as only Pi (KH2PO4), only Po (phytate) or Pi + Po (KH2PO4+ phytate). The results showed that dry matter and phosphorus accumulation of wild barley in the different treatments was ranked as Pi > Pi + Po > Po > CK. In addition, dry matter yield and phosphorus uptake of wild barley with high P-efficiency exhibited significantly greater than that with low P-efficiency. The concentration of soil available phosphorus was significantly different after application of different phosphorus sources, which was presented as Pi > Pi + Po > Po. The concentration of soil available phosphorus in high P-efficiency wild barley was significantly higher than that of low P-efficiency in the rhizosphere soil. There was a deficit in rhizosphere available phosphorus of high P-efficiency wild barley, especially in Pi and Pi+Po treatments. The inorganic phosphorus fractions increased with the increasing Pi treatment, and the concentrations of inorganic phosphorus fractions in soil were sorted as follows: Ca10-P > O-P > Fe-P > Al-P > Ca2-P > Ca8-P. The contents of Ca2-P and Ca8-P for high P-efficiency wild barley showed deficits in rhizosphere soil under each phosphorus source treatment. In addition, enrichment of Al-P and Fe-P was observed in Pi treatment in rhizosphere soil. The concentrations of organic phosphorus fractions in soil were sorted as follows: moderate labile organic phosphorus > moderate resistant, resistant organic phosphorus > labile organic phosphorus. The labile and moderate labile organic phosphorus enriched in rhizosphere soil and the greatest enrichment appeared in Pi treatment. Furthermore, the concentrations of moderate resistant organic phosphorus and resistant

Diphenylarsinic acid contaminated soil remediation by titanium dioxide (P25) photocatalysis: Degradation pathway, optimization of operating parameters and effects of soil properties

International Nuclear Information System (INIS)

Wang, A-nan; Teng, Ying; Hu, Xue-feng; Wu, Long-hua; Huang, Yu-juan; Luo, Yong-ming; Christie, Peter

2016-01-01

Diphenylarsinic acid (DPAA) is formed during the leakage of arsenic chemical weapons in sites and poses a high risk to biota. However, remediation methods for DPAA contaminated soils are rare. Here, the photocatalytic oxidation (PCO) process by nano-sized titanium dioxide (TiO_2) was applied to degrade DPAA in soil. The degradation pathway was firstly studied, and arsenate was identified as the final product. Then, an orthogonal array experimental design of L_9(3)"4, only 9 experiments were needed, instead of 81 experiments in a conventional one-factor-at-a-time, was used to optimize the operational parameters soil:water ratio, TiO_2 dosage, irradiation time and light intensity to increase DPAA removal efficiency. Soil:water ratio was found to have a more significant effect on DPAA removal efficiency than other properties. The optimum conditions to treat 4 g soil with a DPAA concentration of 20 mg kg"−"1 were found to be a 1:10 soil: water ratio, 40 mW cm"−"2 light intensity, 5% TiO_2 in soil, and a 3-hour irradiation time, with a removal efficiency of up to 82.7%. Furthermore, this method (except for a change in irradiation time from 3 to 1.5 h) was validated in nine different soils and the removal efficiencies ranged from 57.0 to 78.6%. Removal efficiencies were found to be negatively correlated with soil electrical conductivity, organic matter content, pH and total phosphorus content. Finally, coupled with electron spin resonance (ESR) measurement, these soil properties affected the generation of OH• by TiO_2 in soil slurry. This study suggests that TiO_2 photocatalytic oxidation is a promising treatment for removing DPAA from soil. - Highlights: • DPAA was degraded into arsenate through TiO_2 (P25) photocatalytic oxidation. • Soil/water ratio was more influential on the removal of DPAA in soil by TiO_2 (P25). • Soil properties affected the adsorption of DPAA and the generation of OH• by TiO_2.

Use of radioactive 32P technique to study phosphate rock dissolution in acid soils

International Nuclear Information System (INIS)

Mahisarakul, J.; Mullins, G.L.; Chien, S.H.

2002-01-01

A laboratory experiment was conducted to evaluate the dissolution of six sources of phosphate rock in two acid soils (Ultisols): a sandy soil and a red clay soil. Labile P was determined using the radioactive 32 P technique for Pi extractable P and resin extractable P. Incubations were conducted for 0, 1, 2, 3, 4 and 5 weeks for 32 P exchangeable technique, 0 and 5 weeks for Pi technique and 5 weeks for resin technique. Rates of PR were 0 and 400 mgP/ha. The results showed that labile P in the sandy soil decreased from 0-1 weeks for all the PRs except Hahotoe PR and Hazara PR's. Between 1 and 5 weeks labile P remained relatively constant. The ranking of labile P from PRs was: North Carolina = Kouribga > Matam > Hahotoe = Hazara> Patos de Minas. In the red soil, labile P from all PRs appeared to be relatively unchanged during the 0-5 week incubation. Pi extractable P in sandy soil showed no significant differences due to incubation time. In the red clay soil, there was a significant decrease in Pi-P extracted from soil mixtures with PRs after 5 weeks as compared to 0 weeks. Results of the Resin-extractable P in both sandy and red soils were in agreement with labile P as measured by 32 P exchange technique. (author)

Sorption behavior of cesium on various soils under different pH levels

International Nuclear Information System (INIS)

Giannakopoulou, F.; Haidouti, C.; Chronopoulou, A.; Gasparatos, D.

2007-01-01

In the present study we investigated the sorption behavior of Cs in four different soils (sandyloam, loam, clayloam and clay) by using batch experiment. Cs sorption characteristics of the studied soils were examined at 4 mg L -1 Cs concentration, at various pH levels, at room temperature and with 0.01 M CaCl 2 as a background electrolyte. Among different soils the decrease of k d (distribution coefficient) of cesium, at all pH levels, followed the sequence sandyloam > loam > clayloam > clay, indicating that the particle size fractions and especially the clay content plays predominant role on sorption of Cs. The effect of pH on cesium sorption displays a similar pattern for all soils, depending on soil type. At acid pH levels less cesium was sorbed, due to a greater competition with other cations for available sorption sites. The maximum sorption of Cs was observed at pH 8, where the negative charge density on the surface of the absorbents was the highest. For all soils was observed significantly lower Cs sorption at pH 10

Availability of rock phosphate with low P content in some Albanian soil: use of 32PO4

International Nuclear Information System (INIS)

Fardeau, J.C.; Migadel, F.; Gjermani, A.; Malja, S.

1983-10-01

The availability of a calcareous low P content rock phosphate (4,3% P) was measured. This Albanian ore was used, in pot experiments, on various local soils whose the pH is situated between 4,9 to 7,5. This phosphate was labelled with 32 P and 45 Ca in a reactor. The residual effect of this fertilizer was deduced from the results of isotopic dilution kinetic of phosphate ions realized in soil-solution systemes. The main results can be summarized as follow: 1. When the soil-water pH was higher than 6,1, the utilization coefficient of phosphorus was minus than 1%, even with 5,5 mounths. 2. The ratio of P and Ca derived from fertilizer and taken up by the crop is most generally different of those measured in the fertilizer. It depends of the soil constitution. 3. The analysis of isotopic dilution kinetic of phosphate ions shows that in the major part of these soils, whose the fixing capacity is very high, the rock phosphate and also superphosphate at 230 kg P 2 O 5 .ha -1 rate does not increase available soil phosphorus; it is only with rates over 800 kg P 2 O 5 .ha -1 that this objective can be reached. These results explain again that the fixing capacity of soil for phosphorus is a characteristic more useful for fertilization technique than the available phosphorus quantity [fr

Fluctuations in ammonia oxidizing communities across agricultural soils are driven by soil structure and pH

Directory of Open Access Journals (Sweden)

Michele C ePereira e Silva

2012-03-01

Full Text Available The milieu in soil in which microorganisms dwell is never constant. Conditions such as temperature, water availability, pH and nutrients frequently change, impacting the overall functioning of the soil system. To understand the effects of such factors on soil functioning, proxies (indicators of soil function are needed that, in a sensitive manner, reveal normal amplitude of variation. Thus, the so-called normal operating range (NOR of soil can be defined. In this study we determined different components of nitrification by analyzing, in eight agricultural soils, how the community structures and sizes of ammonia oxidizing bacteria and archaea (AOB and AOA, respectively, and their activity, fluctuate over spatial and temporal scales. The results indicated that soil pH and soil type are the main factors that influence the size and structure of the AOA and AOB, as well as their function. The nitrification rates varied between 0.11 ± 0.03 µgN.h-1.gdw-1 and 1.68 ± 0.11 µgN.h-1.gdw-1, being higher in soils with higher clay content (1.09 ± 0.12 µgN.h-1.gdw-1 and lower in soils with lower clay percentages (0.27 ± 0.04 µgN.h-1.gdw-1. Nitrifying activity was driven by soil pH, mostly related to its effect on AOA but not on AOB abundance. Regarding the influence of soil parameters, clay content was the main soil factor shaping the structure of both the AOA and AOB communities. Overall, the potential nitrifying activities were higher and more variable over time in the clayey than in the sandy soils. Whereas the structure of AOB fluctuated more (62.7 ± 2.10% the structure of AOA communities showed lower amplitude of variation (53.65 ± 3.37%. Similar trends were observed for the sizes of these communities. The present work represents a first step towards defining a NOR for soil nitrification. Moreover, the clear effect of soil texture established here suggests that the NOR should be defined in a soil-type-specific manner.

pH-Dependent Bioavailability, Speciation, and Phytotoxicity of Tungsten (W) in Soil Affect Growth and Molybdoenzyme Activity of Nodulated Soybeans.

Science.gov (United States)

Oburger, Eva; Vergara Cid, Carolina; Preiner, Julian; Hu, Junjian; Hann, Stephan; Wanek, Wolfgang; Richter, Andreas

2018-06-05

Increasing use of tungsten (W)-based products opened new pathways for W into environmental systems. Due to its chemical alikeness with molybdenum (Mo), W is expected to behave similarly to its "twin element", Mo; however, our knowledge of the behavior of W in the plant-soil environment remains inadequate. The aim of this study was to investigate plant growth as well as W and nutrient uptake depending on soil chemical properties such as soil pH and texture. Soybean ( Glycine max cv. Primus) was grown on two acidic soils differing in soil texture that were either kept at their natural soil pH (pH of 4.5-5) or limed (pH of ≥7) and amended with increasing concentrations of metallic W (control and 500 and 5000 mg kg -1 ). In addition, the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N 2 fixation (nitrogenase) was also investigated. Our results showed that the risk of W entering the food web was significantly greater in high-pH soils due to increased solubility of mainly monomeric W. The effect of soil texture on W solubility and phytoavailability was less pronounced compared to soil pH. Particularly at intermediate W additions (W 500 mg kg -1 ), symbiotic nitrogen fixation was able to compensate for reduced leaf nitrate reductase activity. When W soil solution concentrations became too toxic (W 5000 mg kg -1 ), nodulation was more strongly inhibited than nitrogenase activity in the few nodules formed, suggesting a more-efficient detoxification and compartmentalization mechanism in nodules than in soybean leaves. The increasing presence of polymeric W species observed in low-pH soils spiked with high W concentrations resulted in decreased W uptake. Simultaneously, polymeric W species had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our study demonstrates the importance of accounting for soil pH in risk assessment studies of W in the plant-soil

Improved Design Basis for Laterally Loaded Large Diameter Pile

DEFF Research Database (Denmark)

Leth, Caspar Thrane

of the diameter, depth and soil strength, and increase of each these will give an increase in stiffness. • Cyclic response of a lateral loaded pile is depended on the characteristics of the cyclic load. Behaviour of a monopile is a classic soil-structure interaction problem depending on the pile stiffness....... The target is to improve the use of monopiles as preferred support structure beyond the current limit at a water depth of 30 m. Design of foundations for wind turbines has a large focus on the stiffness of the combined structure, turbine-tower-foundation, which has an influence on the environmental loads...... initial response and a higher ultimate capacity. The initial stiffness of the soil-structure interaction measured in the centrifuge tests, equivalent to initial stiffness of p-y curves, shows a dependency of depth and diameter. Control issues in relation to cyclic tests have resulted in tests...

Laser-induced breakdown spectroscopy: Extending its application to soil pH measurements

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Edilene Cristina, E-mail: edilene@iq.unesp.br [São Paulo State University – UNESP, Analytical Chemistry Department, Rua Prof. Francisco Degni 55, CEP 14800-060, Araraquara, SP (Brazil); Gomes Neto, José A. [São Paulo State University – UNESP, Analytical Chemistry Department, Rua Prof. Francisco Degni 55, CEP 14800-060, Araraquara, SP (Brazil); Milori, Débora M.B.P.; Ferreira, Ednaldo José [Embrapa Agricultural Instrumentation, Rua XV de Novembro 1452, CEP 13560-970, São Carlos, SP (Brazil); Anzano, Jesús Manuel [Laser Laboratory & Environment, Faculty of Sciences, University of Zaragoza, C/. Pedro Cerbuna 12, 50009, Zaragoza (Spain)

2015-08-01

Acid–base equilibria are involved in almost all the processes that occur in soil. The bioavailability of nutrients for plants, for instance, depends on the solubilization of mineral nutrients in the soil solution, which is a pH-dependent process. The determination of pH in soil solutions is usually carried out by potentiometry using a glass membrane electrode, after extracting some of the soil components with water or CaCl{sub 2} solution. The present work describes a simple method for determining the pH of soil, using laser-induced breakdown spectroscopy (LIBS). Sixty samples presenting different textural composition and pH (previously determined by potentiometry) were employed. The samples were divided into a calibration set with fifty samples and a validation set with ten samples. LIBS spectra were recorded for each pelleted sample using laser pulse energy of 115 mJ. The intensities of thirty-two emission lines for Al, Ca, H, and O were used to fit a partial least squares (PLS) model. The model was validated by prediction of the pH of the validation set samples, which showed good agreement with the reference values. The prediction mean absolute error was 0.3 pH units and the root mean square error of the prediction was 0.4. These results highlight the potential of LIBS for use in other applications beyond elemental composition determinations. For soil analysis, the proposed method offers the possibility of determining pH, in addition to nutrients and contaminants, using a single LIBS measurement. - Highlights: • Physical, chemical, and biological properties of soil are influenced by pH. • The pH of mineral soils is normally determined in slurries of water and soil sample by potentiometric measurements. • The association of LIBS elemental emissions with multivariate strategies of analysis has become LIBS a powerful technique. • LIBS was unprecedentedly applied for direct pH determination in different kinds of soil sample. • The clean and fast proposed

Fluctuations in ammonia oxidizing communities across agricultural soils are driven by soil structure and pH

NARCIS (Netherlands)

de Cassia Pereira e Silva, M.; Poly, F.; Guillaumaud, N.; van Elsas, J.D.; Falcao Salles, J.

2012-01-01

The milieu in soil in which microorganisms dwell is never constant. Conditions such as temperature, water availability, pH and nutrients frequently change, impacting the overall functioning of the soil system. To understand the effects of such factors on soil functioning, proxies (indicators) of

Microbial community structure and soil pH correspond to methane production in Arctic Alaska soils.

Science.gov (United States)

Wagner, Robert; Zona, Donatella; Oechel, Walter; Lipson, David

2017-08-01

While there is no doubt that biogenic methane production in the Arctic is an important aspect of global methane emissions, the relative roles of microbial community characteristics and soil environmental conditions in controlling Arctic methane emissions remains uncertain. Here, relevant methane-cycling microbial groups were investigated at two remote Arctic sites with respect to soil potential methane production (PMP). Percent abundances of methanogens and iron-reducing bacteria correlated with increased PMP, while methanotrophs correlated with decreased PMP. Interestingly, α-diversity of the methanogens was positively correlated with PMP, while β-diversity was unrelated to PMP. The β-diversity of the entire microbial community, however, was related to PMP. Shannon diversity was a better correlate of PMP than Simpson diversity across analyses, while rarefied species richness was a weak correlate of PMP. These results demonstrate the following: first, soil pH and microbial community structure both probably control methane production in Arctic soils. Second, there may be high functional redundancy in the methanogens with regard to methane production. Third, iron-reducing bacteria co-occur with methanogens in Arctic soils, and iron-reduction-mediated effects on methanogenesis may be controlled by α- and β-diversity. And finally, species evenness and rare species abundances may be driving relationships between microbial groups, influencing Arctic methane production. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Pollution load index for heavy metals in Mian-Ab plain soil, Khuzestan, Iran.

Science.gov (United States)

Jorfi, Sahand; Maleki, Rohangiz; Jaafarzadeh, Neemat; Ahmadi, Mehdi

2017-12-01

Soil pollution by heavy metals is a major concern in agricultural area. Potential impact of heavy metals in agricultural soil on human health by accumulating in food chain demonstrated elsewhere. In this regard Mian-Ab plain as a major agricultural site of Khuzestan province considered for Arsenic, cadmium and lead concentration as the main potential toxic pollutants in soil. 50 topsoil samples were collected and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Also Contamination level of selected heavy metals in Mian-Ab Plain, was assessed by single factor contaminant index (PI) and pollution load index (PLI). Results show mean concentration of arsenic, cadmium and lead were 2.52, 0.30 and 7.21 mg kg -1 . Base on PLI results 12 point (24%) of the studied area show moderately polluted and 38 point (76%) show unpolluted area.

Effect of pH on the adsorption of carbendazim in Polish mineral soils

International Nuclear Information System (INIS)

Paszko, Tadeusz

2012-01-01

The study aimed to determine the influence of pH on the adsorption of carbendazim in soil profiles of three mineral agricultural soils: Hyperdystric Arenosol, Haplic Luvisol and Hypereutric Cambisol. In the examined pH range between 3 and 7 the adsorption of carbendazim was inversely correlated to the pH of the soil. The adsorption coefficients were in the range between 0.3 and 151.8 mL g −1 . Decreasing the pH in the soil suspensions from 7 to 3 increased the value of this coefficient by 3 to 70 times. A decrease in the amounts of organic matter down the soil profiles was not associated with weaker carbendazim adsorption. In the samples from all soil horizons, at pH values between 3 and 6, the predominant sorption process was carbendazim adsorption on clay minerals. The adsorption of carbendazim on organic matter prevailed over that on clays only at pH > 6 and only in the Ap horizon of the examined soils. The developed mathematical models yielded very good results when the adsorption of the protonated form of carbendazim was assumed to be the predominant adsorption process on clays together with the adsorption of neutral molecules on organic matter and clays. The results from both the model fitting and the experiments revealed the negative effect of Al oxides and hydroxides and Al cations on the adsorption of the protonated form of carbendazim on clay minerals. The developed models successfully described the pH-dependent adsorption processes of carbendazim for both data from particular soil horizons and those from all three examined soil profiles. -- Highlights: ► Adsorption of carbendazim in soils was inversely correlated to soil pH. ► At low pH carbendazim was adsorbed predominantly by clay minerals. ► Al 3+ influenced adsorption of the protonated form of carbendazim on clays. ► Created models predict pH-dependent sorption processes in the whole soil profiles.

Performance of low pH biofilters treating a paint solvent mixture: Continuous and intermittent loading

International Nuclear Information System (INIS)

Qi Bing; Moe, William M.

2006-01-01

Two biofilters packed with a reticulated polyurethane foam medium were inoculated with a compost-derived enrichment culture grown under acidic conditions (pH 3.0) and then operated over a period lasting 63 days. Both biofilters were supplied with a humidified gas stream containing a five-component mixture of acetone, methyl ethyl ketone, toluene, ethylbenzene, and p-xylene at a total VOC loading rate 80.3 g m -3 h -1 to simulate treatment of air emissions resulting from manufacture of reformulated paint. One biofilter was operated under continuous loading conditions and the other received intermittent loading with contaminants supplied only 8 h/day. Nutrient solution with pH 3.0 was supplied approximately once per week to provide nitrogen and other nutrients. Data are presented which demonstrate that undefined mixed cultures acclimated at low pH can successfully treat paint solvent mixtures in biofilters. The biofilter receiving continuous loading reached high overall removal efficiency (greater than 90% overall removal) 3 weeks after startup, and performance increased over time reaching overall removal in the range of 97-99% after 50 days. Performance of the intermittently loaded biofilter developed more slowly, requiring 6 weeks to stabilize at an overall removal efficiency in excess of 90%. In both biofilters, ketone components were more rapidly degraded than aromatic components, and removal of aromatic compounds was somewhat unstable even after 2 months of biofilter operation. Scanning electron microscopy (SEM) revealed that fungi dominated the microbial populations in both biofilters

Startup analysis for a high temperature gas loaded heat pipe

Science.gov (United States)

Sockol, P. M.

1973-01-01

A model for the rapid startup of a high-temperature gas-loaded heat pipe is presented. A two-dimensional diffusion analysis is used to determine the rate of energy transport by the vapor between the hot and cold zones of the pipe. The vapor transport rate is then incorporated in a simple thermal model of the startup of a radiation-cooled heat pipe. Numerical results for an argon-lithium system show that radial diffusion to the cold wall can produce large vapor flow rates during a rapid startup. The results also show that startup is not initiated until the vapor pressure p sub v in the hot zone reaches a precise value proportional to the initial gas pressure p sub i. Through proper choice of p sub i, startup can be delayed until p sub v is large enough to support a heat-transfer rate sufficient to overcome a thermal load on the heat pipe.

High Temperature Radio Frequency Loads

CERN Document Server

Federmann, S; Grudiev, A; Montesinos, E; Syratchev, I

2011-01-01

In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet withmore than 150 ◦C and high pressure has a higher value than water with 50 ◦C under low pressure. Conventional RF power loads containing dielectric and magnetic materials as well as sensitive ceramic windows usually do not permit going much higher than 90 ◦C. Here we present and discuss several design concepts for "metal only" RF high power loads. One concept is the application of magnetic steel corrugated waveguides near cutoff – this concept could find practical use above several GHz. Another solution are resonant structures made of steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage of the rather high losses of normal steel may also be used in coaxial line geometries with large di...

Reduction of exchangeable calcium and magnesium in soil with increasing pH

Directory of Open Access Journals (Sweden)

Miyazawa Mário

2001-01-01

Full Text Available A laboratory study was conducted with soil samples and synthetic solutions to investigate possible mechanisms related with reduction in KCl exchangeable Ca and Mg with increasing pH. Increasing soil pH over 5.3 with CaCO3 added to the soil and with NaOH solution added to soil/KCl suspension increased adsorptions of Ca and Mg. The reduction of Mg was greater than Ca and was related to the concentration of soil exchangeable Al. The decreases of soluble Ca and Mg following addition of Al in synthetic solution were at pH > 7.5. The isomorphic coprecipitation reaction with Al compounds may be the most possible mechanism responsible for the decrease of exchangeable Ca and Mg with increasing pH. Possible chemical reactions are presented.

Soil pH controls the environmental availability of phosphorus: Experimental and mechanistic modelling approaches

International Nuclear Information System (INIS)

Devau, Nicolas; Cadre, Edith Le; Hinsinger, Philippe; Jaillard, Benoit; Gerard, Frederic

2009-01-01

Inorganic P is the least mobile major nutrient in most soils and is frequently the prime limiting factor for plant growth in terrestrial ecosystems. In this study, the extraction of soil inorganic P with CaCl 2 (P-CaCl 2 ) and geochemical modelling were combined in order to unravel the processes controlling the environmentally available P (EAP) of a soil over a range of pH values (pH ∼ 4-10). Mechanistic descriptions of the adsorption of cations and anions by the soil constituents were used (1-pK Triple Plane, ion-exchange and NICA-Donnan models). These models are implemented into the geochemical code Visual MINTEQ. An additive approach was used for their application to the surface horizon of a Cambisol. The geochemical code accurately reproduced the concentration of extracted P at the different soil pH values (R 2 = 0.9, RMSE = 0.03 mg kg -1 ). Model parameters were either directly found in the literature or estimated by fitting published experimental results in single mineral systems. The strong agreement between measurements and modelling results demonstrated that adsorption processes exerted a major control on the EAP of the soil over a large range of pH values. An influence of the precipitation of P-containing mineral is discounted based on thermodynamic calculations. Modelling results indicated that the variations in P-CaCl 2 with soil pH were controlled by the deprotonation/protonation of the surface hydroxyl groups, the distribution of P surface complexes, and the adsorption of Ca and Cl from the electrolyte background. Iron-oxides and gibbsite were found to be the major P-adsorbing soil constituents at acidic and alkaline pHs, whereas P was mainly adsorbed by clay minerals at intermediate pH values. This study demonstrates the efficacy of geochemical modelling to understand soil processes, and the applicability of mechanistic adsorption models to a 'real' soil, with its mineralogical complexity and the additional contribution of soil organic matter.

Soil pH controls the environmental availability of phosphorus: Experimental and mechanistic modelling approaches

Energy Technology Data Exchange (ETDEWEB)

Devau, Nicolas [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Cadre, Edith Le [Supagro, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Hinsinger, Philippe; Jaillard, Benoit [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France); Gerard, Frederic, E-mail: gerard@supagro.inra.fr [INRA, UMR 1222 Eco and Sols - Ecologie Fonctionnelle et Biogeochimie des Sols (INRA-IRD-SupAgro), Place Viala, F-34060 Montpellier (France)

2009-11-15

Inorganic P is the least mobile major nutrient in most soils and is frequently the prime limiting factor for plant growth in terrestrial ecosystems. In this study, the extraction of soil inorganic P with CaCl{sub 2} (P-CaCl{sub 2}) and geochemical modelling were combined in order to unravel the processes controlling the environmentally available P (EAP) of a soil over a range of pH values (pH {approx} 4-10). Mechanistic descriptions of the adsorption of cations and anions by the soil constituents were used (1-pK Triple Plane, ion-exchange and NICA-Donnan models). These models are implemented into the geochemical code Visual MINTEQ. An additive approach was used for their application to the surface horizon of a Cambisol. The geochemical code accurately reproduced the concentration of extracted P at the different soil pH values (R{sup 2} = 0.9, RMSE = 0.03 mg kg{sup -1}). Model parameters were either directly found in the literature or estimated by fitting published experimental results in single mineral systems. The strong agreement between measurements and modelling results demonstrated that adsorption processes exerted a major control on the EAP of the soil over a large range of pH values. An influence of the precipitation of P-containing mineral is discounted based on thermodynamic calculations. Modelling results indicated that the variations in P-CaCl{sub 2} with soil pH were controlled by the deprotonation/protonation of the surface hydroxyl groups, the distribution of P surface complexes, and the adsorption of Ca and Cl from the electrolyte background. Iron-oxides and gibbsite were found to be the major P-adsorbing soil constituents at acidic and alkaline pHs, whereas P was mainly adsorbed by clay minerals at intermediate pH values. This study demonstrates the efficacy of geochemical modelling to understand soil processes, and the applicability of mechanistic adsorption models to a 'real' soil, with its mineralogical complexity and the additional

Assessment of Non-Point Source Total Phosphorus Pollution from Different Land Use and Soil Types in a Mid-High Latitude Region of China

Directory of Open Access Journals (Sweden)

Zhiwei Wang

2016-11-01

Full Text Available The transport characteristics of phosphorus in soil and the assessment of its environmental risk have become hot topics in the environmental and agricultural fields. The Sanjiang Plain is an important grain production base in China, and it is characterised by serious land use change caused by large-scale agricultural exploitation. Agricultural inputs and tillage management have destroyed the soil nutrient balance formed over long-term conditions. There are few studies on non-point source phosphorus pollution in the Sanjiang Plain, which is the largest swampy low plain in a mid-high-latitude region in China. Most studies have focused on the water quality of rivers in marsh areas, or the export mechanism of phosphorus from specific land uses. They were conducted using experimental methods or empirical models, and need further development towards mechanism models and the macro-scale. The question is how to find a way to couple processes in phosphorus cycling and a distributed hydrological model considering local hydrological features. In this study, we report an attempt to use a distributed phosphorus transport model to analyse non-point source total phosphorus pollution from different land uses and soil types on the Sanjiang Plain. The total phosphorus concentration generally shows an annually increasing trend in the study area. The total phosphorus load intensity is heterogeneous in different land use types and different soil types. The average total phosphorus load intensity of different land use types can be ranked in descending order from paddy field, dry land, wetlands, grassland, and forestland. The average total phosphorus load intensity of different soil types can be ranked in descending order: paddy soil, bog soil, planosol, meadow soil, black soil, and dark brown earth. The dry land and paddy fields account for the majority of total phosphorus load in the study area. This is mainly caused by extensive use of phosphate fertilizer on the

Soil sterilization affects aging-related sequestration and bioavailability of p,p'-DDE and anthracene to earthworms

International Nuclear Information System (INIS)

Slizovskiy, Ilya B.; Kelsey, Jason W.

2010-01-01

Laboratory experiments investigated the effects of soil sterilization and compound aging on the bioaccumulation of spiked p,p'-DDE and anthracene by Eisenia fetida and Lumbricus terrestris. Declines in bioavailability occurred as pollutant residence time in both sterile and non-sterile soils increased from 3 to 203 d. Accumulation was generally higher in sterile soils during initial periods of aging (from 3-103 d). By 203 d, however, bioavailability of the compounds was unaffected by sterilization. Gamma irradiation and autoclaving may have altered bioavailability by inducing changes in the chemistry of soil organic matter (SOM). The results support a dual-mode partitioning sorption model in which the SOM components associated with short-term sorption (the 'soft' or 'rubbery' phases) are more affected than are the components associated with long-term sorption (the 'glassy' or microcrystalline phases). Risk assessments based on data from experiments in which sterile soil was used could overestimate exposure and bioaccumulation of pollutants. - Soil sterilization affects aging-related sequestration of organic contaminants.

Phosphate Sorption Characteristics and External P Requirements of Selected South African Soils

Directory of Open Access Journals (Sweden)

E. M. Gichangi

2008-10-01

Full Text Available The Transkei is the largest consolidated area in South Africa where land is held by smallholder farmers but little is known about the extent of phosphate fixation in the region. This study was conducted to determine the phosphate sorption properties and external P requirements (EPR of selected soils from the Transkei region, South Africa and to relate derived sorption values to selected soil parameters. The P sorption maxima and EPR values varied widely ranging from 192.3 to 909.1 mg P kg−1 and from 2 to 123 mg P kg−1−1 soil, respectively. Citrate dithionite bicarbonate-extractable aluminum explained most of the observed variations in P sorption. About 43% of the soils were found to be moderate P fixers and may need management interventions to ensure adequate P availability to crops. The single point sorption index accurately predicted the EPR of the soils obviating the need to use multiple point sorption isotherms. The results suggested that the use of blanket phosphate fertilizer recommendations may not be a good strategy for the region as it may lead to under-application or over-application of P in some areas.

Phosphorus in soil treatment systems: accumulation and mobility.

Science.gov (United States)

Eveborn, David; Gustafsson, Jon Petter; Elmefors, Elin; Yu, Lin; Eriksson, Ann-Kristin; Ljung, Emelie; Renman, Gunno

2014-11-01

Septic tanks with subsequent soil treatment systems (STS) are a common treatment technique for domestic wastewater in rural areas. Phosphorus (P) leakage from such systems may pose a risk to water quality (especially if they are located relatively close to surface waters). In this study, six STS in Sweden (11-28 years old) were examined. Samples taken from the unsaturated subsoil beneath the distribution pipes were investigated by means of batch and column experiments, and accumulated phosphorus were characterized through X-ray absorption near edge structure (XANES) analysis. At all sites the wastewater had clearly influenced the soil. This was observed through decreased pH, increased amounts of oxalate extractable metals and at some sites altered P sorption properties. The amount of accumulated P in the STS were found to be between 0.32 and 0.87 kg m(-3), which in most cases was just a fraction of the estimated P load (<30%). Column studies revealed that high P concentrations (up to 6 mg L(-1)) were leached from the material when deionized water was applied. However, the response to deionized water varied between the sites. As evidenced by XANES analysis, aluminium phosphates or P adsorbed to aluminium (hydr)oxides, as well as organically bound P, were important sinks for P. Generally soils with a high content of oxalate-extractable Al were also less vulnerable to P leakage. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ciprofloxacin-loaded PLGA nanoparticles against cystic fibrosis P. aeruginosa lung infections.

Science.gov (United States)

Günday Türeli, Nazende; Torge, Afra; Juntke, Jenny; Schwarz, Bianca C; Schneider-Daum, Nicole; Türeli, Akif Emre; Lehr, Claus-Michael; Schneider, Marc

2017-08-01

Current pulmonary treatments against Pseudomonas aeruginosa infections in cystic fibrosis (CF) lung suffer from deactivation of the drug and immobilization in thick and viscous biofilm/mucus blend, along with the general antibiotic resistance. Administration of nanoparticles (NPs) with high antibiotic load capable of penetrating the tight mesh of biofilm/mucus can be an advent to overcome the treatment bottlenecks. Biodegradable and biocompatible polymer nanoparticles efficiently loaded with ciprofloxacin complex offer a solution for emerging treatment strategies. NPs were prepared under controlled conditions by utilizing MicroJet Reactor (MJR) to yield a particle size of 190.4±28.6nm with 0.089 PDI. Encapsulation efficiency of the drug was 79% resulting in a loading of 14%. Release was determined to be controlled and medium-independent in PBS, PBS+0.2% Tween 80 and simulated lung fluid. Cytotoxicity assays with Calu-3 cells and CF bronchial epithelial cells (CFBE41o - ) indicated that complex-loaded PLGA NPs were non-toxic at concentrations ≫ MIC cipro against lab strains of the bacteria. Antibacterial activity tests revealed enhanced activity when applied as nanoparticles. NPs' colloidal stability in mucus was proven. Notably, a decrease in mucus turbidity was observed upon incubation with NPs. Herewith, ciprofloxacin complex-loaded PLGA NPs are introduced as promising pulmonary nano drug delivery systems against P.aeruginosa infections in CF lung. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis, Characterization and Drug Loading of Multiresponsive p[NIPAm-co-PEGMA] (core/p[NIPAm-co-AAc] (Shell Nanogels with Monodisperse Size Distributions

Directory of Open Access Journals (Sweden)

Rajesh Raju

2018-03-01

Full Text Available We report the synthesis and properties of temperature- and pH-responsive p([NIPAm-co-PEGMA] (core/[NIPAm-co-AAc] (shell nanogels with narrow size distributions, tunable sizes and increased drug loading efficiencies. The core-shell nanogels were synthesized using an optimized two-stage seeded polymerization methodology. The core-shell nanogels show a narrow size distribution and controllable physico-chemical properties. The hydrodynamic sizes, charge distributions, temperature-induced volume phase transition behaviors, pH-responsive behaviors and drug loading capabilities of the core-shell nanogels were investigated using transmission electron microscopy, zeta potential measurements, dynamic light scattering and UV-Vis spectroscopy. The size of the core-shell nanogels was controlled by polymerizing NIPAm with crosslinker poly(ethylene glycol dimethacrylate (PEGDMA of different molecular weights (Mn-200, 400, 550 and 750 g/mol during the core synthesis. It was found that the swelling/deswelling kinetics of the nanogels was sharp and reversible; with its volume phase transition temperature in the range of 40–42 °C. Furthermore, the nanogels loaded with l-3,4-dihydroxyphenylalanine (L-DOPA, using a modified breathing-in mechanism, showed high loading and encapsulation efficiencies, providing potential possibilities of such nanogels for biomedical applications.

Evaluation of coal combustion byproducts as soil liming materials - their influence on soil pH and enzyme activities

Energy Technology Data Exchange (ETDEWEB)

McCarty, G W; Siddaramappa, R; Wright, R J; Codling, E E; Gao, G

1994-03-01

To evaluate coal combustion byproducts as liming materials and address issues related to soil quality, the authors compared the influence of different amounts of four combustion byproducts (fly ash and bed ash from a fluidized bed combustion furnace, lime-injected multistage burner residue, and spray dryer residue) and CaCO[sub 3] on soil pH and activities of urease, phosphatase, arylsulfatase, and dehydrogenase in an acidic soil. Studies comparing the influence of the combustion byproducts and CaCO[sub 3] on soil pH showed that on weight basis of application, substantial differences were observed in the ability of these materials to influence soil pH but that such differences decreased markedly after the data were transformed to a CaCO[sub 3] equivalent basis of application. Analysis of covariance for these transformed data indicated that whereas the liming abilities of fly ash and CaCO[sub 3] were not significantly different when compared on the CaCO[sub 3] equivalent basis, those of bed ash, multistage burner residue, and spray dryer residue were less than that of CaCO[sub 3]. Studies comparing the influence of the byproducts and CaCO[sub 3] on soil enzyme activities showed that the effect of these liming materials on the enzyme activities studied was largely due to their influence on soil pH. These studies showed that the combustion byproducts tested functioned as soil liming materials in a manner similar to that of CaCO[sub 3] and seemed to have little adverse effect on soil quality.

Effects of wood-ash addition on nitrogen turnover in a highly nitrogen loaded spruce site. Final project report

International Nuclear Information System (INIS)

Nohrstedt, H.Oe.; Hoegbom, Lars; Nordlund, Sten

2000-04-01

During two consecutive years, it was studied how a fertilization with 4.2 tonnes pelleted bark ash per ha, made six-seven years earlier, affected soil chemistry, nitrogen turnover and soil-water chemistry on a Norway spruce site in SW Sweden. The actual site has a very acidic soil. At the same time, the supply of inorganic N is rich. Measures against soil acidification, e. g. addition of ash or lime, may significantly influence the turnover of N with a subsequent risk for increased leaching. Thus, there is a potential conflict between two urgent environmental goals, i. e. to decrease acidification and to decrease the N load on aquatic ecosystems. In the humus layer and the upper 5 cm of the mineral soil, pH(H 2 O) had increased with at the most 0.2 units because of the ash addition. The easily extractable amounts of Mg, P and nitrate were slightly increased. The potential nitrification in the humus layer was generally higher in the ash treatment, but the difference. was not statistically significant. The soil water at 50 cm depth was 0.1-0.2 pH-units more acidic where ash had been applied. Simultaneously, there were tendencies for higher concentrations of nitrate, Al and K. This is the first time in Sweden that ash fertilization of a closed forest has given clear indications of an increased N leaching. As expected, the ash fertilization decreased the acidity of the top soil. On the contrary, the runoff became more acidic and more rich in Al. Thus, the ash fertilization has counteracted one of its primary goals, i. e. to produce a runoff less toxic to aquatic life. The acidification of the runoff may partially be because of acid production during nitrification

Diphenylarsinic acid contaminated soil remediation by titanium dioxide (P25) photocatalysis: Degradation pathway, optimization of operating parameters and effects of soil properties

Energy Technology Data Exchange (ETDEWEB)

Wang, A-nan [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Teng, Ying [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Hu, Xue-feng [Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Wu, Long-hua; Huang, Yu-juan [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Luo, Yong-ming, E-mail: ymluo@yic.ac.cn [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Christie, Peter [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)

2016-01-15

Diphenylarsinic acid (DPAA) is formed during the leakage of arsenic chemical weapons in sites and poses a high risk to biota. However, remediation methods for DPAA contaminated soils are rare. Here, the photocatalytic oxidation (PCO) process by nano-sized titanium dioxide (TiO{sub 2}) was applied to degrade DPAA in soil. The degradation pathway was firstly studied, and arsenate was identified as the final product. Then, an orthogonal array experimental design of L{sub 9}(3){sup 4}, only 9 experiments were needed, instead of 81 experiments in a conventional one-factor-at-a-time, was used to optimize the operational parameters soil:water ratio, TiO{sub 2} dosage, irradiation time and light intensity to increase DPAA removal efficiency. Soil:water ratio was found to have a more significant effect on DPAA removal efficiency than other properties. The optimum conditions to treat 4 g soil with a DPAA concentration of 20 mg kg{sup −1} were found to be a 1:10 soil: water ratio, 40 mW cm{sup −2} light intensity, 5% TiO{sub 2} in soil, and a 3-hour irradiation time, with a removal efficiency of up to 82.7%. Furthermore, this method (except for a change in irradiation time from 3 to 1.5 h) was validated in nine different soils and the removal efficiencies ranged from 57.0 to 78.6%. Removal efficiencies were found to be negatively correlated with soil electrical conductivity, organic matter content, pH and total phosphorus content. Finally, coupled with electron spin resonance (ESR) measurement, these soil properties affected the generation of OH• by TiO{sub 2} in soil slurry. This study suggests that TiO{sub 2} photocatalytic oxidation is a promising treatment for removing DPAA from soil. - Highlights: • DPAA was degraded into arsenate through TiO{sub 2} (P25) photocatalytic oxidation. • Soil/water ratio was more influential on the removal of DPAA in soil by TiO{sub 2} (P25). • Soil properties affected the adsorption of DPAA and the generation of OH• by Ti

Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men.

Directory of Open Access Journals (Sweden)

Nicholas A Burd

Full Text Available BACKGROUND: We aimed to determine the effect of resistance exercise intensity (%1 repetition maximum-1RM and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression. METHODOLOGY/PRINCIPAL FINDINGS: Fifteen men (21+/-1 years; BMI=24.1+/-0.8 kg/m2 performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM until volitional failure (90FAIL, 30% 1RM work-matched to 90%FAIL (30WM, or 30% 1RM performed until volitional failure (30FAIL. Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX, myofibrillar (MYO, and sarcoplasmic (SARC protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121% and MYO (87% protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199% above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P=0.023 and mTORSer2448 phosphorylation at 4 h post-exercise (P=0.025. Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05 only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237% and 30FAIL (312% conditions. Pax7 mRNA expression increased at 24 h post-exercise (P=0.02 regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition. CONCLUSIONS/SIGNIFICANCE: These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.

High voltage nanosecond generator with pulse repetition rate of 1,000 p.p.s.

Energy Technology Data Exchange (ETDEWEB)

Gubanov, V P; Korovin, S D; Stepchenko, A S [High Current Electronics Institute, Tomsk (Russian Federation)

1997-12-31

A compact high voltage nanosecond generator is described with a pulse repetition rate up to 1000 p.p.s. The generator includes a 30-Ohm coaxial forming line charged by a built-in Tesla transformer with a high coupling coefficient, and a high voltage (N{sub 2}) gas gap switch with gas blowing between the electrodes. The maximum forming line charge voltage is 450 kV, the pulse duration is about 4 ns, and its amplitude for a matched load is up to 200 kV. (author). 3 figs., 9 refs.

Soil pH effects on the interactions between dissolved zinc, non-nano- and nano-ZnO with soil bacterial communities

DEFF Research Database (Denmark)

Read, Daniel S.; Matzke, Marianne; Gweon, Hyun S.

2016-01-01

nanoparticles due to the practice of applying sewage sludge as a fertiliser or as an organic soil improver. However, understanding on the interactions between soil properties, nanoparticles and the organisms that live within soil is lacking, especially with regards to soil bacterial communities. We studied......Zinc oxide nanoparticles (ZnO NPs) are used in an array of products and processes, ranging from personal care products to antifouling paints, textiles, food additives, antibacterial agents and environmental remediation processes. Soils are an environment likely to be exposed to manmade...... the effects of nanoparticulate, non-nanoparticulate and ionic zinc (in the form of zinc chloride) on the composition of bacterial communities in soil with a modified pH range (from pH 4.5 to pH 7.2). We observed strong pH-dependent effects on the interaction between bacterial communities and all forms of zinc...

Determination and Distribution of Critical Loads: Application to the Forest Soils in the Autonomous Region of Madrid; Determinacion y Distribucion de Cargas Criticas: Aplicacion a los Suelos forestales de la comunidad Autonoma de Madrid

Energy Technology Data Exchange (ETDEWEB)

Sousa, M.; Schmid, T.; Rabago, I. [Ciemat, Madrid (Spain)

2000-07-01

The critical loads of acidity and sulphur have been determined for forest soils within the north and north-west of the Autonomous Region of Madrid. The SMB-CCE and SMB-PROFILE Steady state models have been applied using a 1 km x 1 km resolution. the forest ecosystems have been characterised according to the soil and forest type, slope and climatic data using a Geographic Information System. In order to estimate the critical loads, processes such as weathering rate of the parent material, atmospheric deposition, critical alkalinity leaching rate and nutrients absorbed by the vegetation have been considered. In general the forest soils present high critical load values for acidity and sulphur. The more sensitive zones are found in the north of the Sierra of Guadarrama. Independent of the applied methods, the results are associated to the types of soils where Leptosols have the lowest. Cambisoles and Regosoles intermediate and luvisoles the most elevated values. (Author) 40 refs.

Dissolving mechanism of strain P17 on insoluble phosphorus of yellow-brown soil

Directory of Open Access Journals (Sweden)

Zhong Chuan-qing

2014-09-01

Full Text Available Strain P17 was a bacterial strain identified as Bacillus megaterium isolated from ground accumulating phosphate rock powder. The fermentation broth of strain P17 and the yellow-brown soil from Nanjing Agricultural University garden were collected to conduct this study. The simulation of fixed insoluble phosphorous forms after applying calcium superphosphate into yellow-brown soil was performed in pots, while available P and total P of soil were extremely positive correlative with those of groundwater. Then the dissolving effect of strain P17 on insoluble P of yellow-brown soil was studied. Results showed that Bacillus megaterium strain P17 had notable solubilizing effect on insoluble phosphates formed when too much water-soluble phosphorous fertilizer used. During 100 days after inoculation, strain P17 was dominant. Until the 120th day, compared with water addition, available P of strain P17 inoculation treated soil increased by 3 times with calcium superphosphate addition. Besides available P, pH, activity of acid and alkaline phosphatase and population of P-solubilizing microbes were detected respectively. P-solubilizing mechanism of P-solubilizing bacteria strain P17 seems to be a synergetic effect of pH decrease, organic acids, phosphatase, etc.

Application of modified export coefficient method on the load estimation of non-point source nitrogen and phosphorus pollution of soil and water loss in semiarid regions.

Science.gov (United States)

Wu, Lei; Gao, Jian-en; Ma, Xiao-yi; Li, Dan

2015-07-01

Chinese Loess Plateau is considered as one of the most serious soil loss regions in the world, its annual sediment output accounts for 90 % of the total sediment loads of the Yellow River, and most of the Loess Plateau has a very typical characteristic of "soil and water flow together", and water flow in this area performs with a high sand content. Serious soil loss results in nitrogen and phosphorus loss of soil. Special processes of water and soil in the Loess Plateau lead to the loss mechanisms of water, sediment, nitrogen, and phosphorus are different from each other, which are greatly different from other areas of China. In this study, the modified export coefficient method considering the rainfall erosivity factor was proposed to simulate and evaluate non-point source (NPS) nitrogen and phosphorus loss load caused by soil and water loss in the Yanhe River basin of the hilly and gully area, Loess Plateau. The results indicate that (1) compared with the traditional export coefficient method, annual differences of NPS total nitrogen (TN) and total phosphorus (TP) load after considering the rainfall erosivity factor are obvious; it is more in line with the general law of NPS pollution formation in a watershed, and it can reflect the annual variability of NPS pollution more accurately. (2) Under the traditional and modified conditions, annual changes of NPS TN and TP load in four counties (districts) took on the similar trends from 1999 to 2008; the load emission intensity not only is closely related to rainfall intensity but also to the regional distribution of land use and other pollution sources. (3) The output structure, source composition, and contribution rate of NPS pollution load under the modified method are basically the same with the traditional method. The average output structure of TN from land use and rural life is about 66.5 and 17.1 %, the TP is about 53.8 and 32.7 %; the maximum source composition of TN (59 %) is farmland; the maximum source

Degradation of isobutanal at high loading rates in a compost biofilter.

Science.gov (United States)

Sercu, Bram; Demeestere, Kristof; Baillieul, Hans; Van Langenhove, Herman; Verstraete, Willy

2005-08-01

Biofiltration has been increasingly used for cleaning waste gases, mostly containing low concentrations of odorous compounds. To expand the application area of this technology, the biofiltration of higher pollutant loading rates has to be investigated. This article focuses on the biodegradation of isobutanal (IBAL) in a compost biofilter (BF) at mass loading rates between 211 and 4123 g/m3/day (30-590 ppm(v)). At mass loading rates up to 785 g/m3/day, near 100% removal efficiencies could be obtained. However, after increasing the loading rate to 1500-1900 g/m3/ day, the degradation efficiency decreased to 62-98%. In addition, a pH decrease and production of isobutanol (IBOL) and isobutyric acid (IBAC) were observed. This is the first report showing that an aldehyde can act as electron donor as well as acceptor in a BF. To study the effects of pH, compost moisture content, and electron acceptor availability on the biofiltration of IBAL, IBOL, and IBAC, additional batch and continuous experiments were performed. A pH of 5.2 reduced the IBAL degradation rate and inhibited the IBOL degradation, although adaptation of the microorganisms to low pH was observed in the BFs. IBAC was not degraded in the batch experiments. High moisture content (51%) initially had no effect on the IBOL production, although it negatively affected the IBAL elimination increasingly during a 21-day time-course experiment. In batch experiments, the reduction of IBAL to IBOL did not decrease when the amount of available electron acceptors (oxygen or nitrate) was increased. The IBAL removal efficiency at higher loading rates was limited by a combination of nutrient limitation, pH decrease, and dehydration, and the importance of each limiting factor depended on the influent concentration.

Spatial and temporal variations of loads and sources of total and dissolved Phosphorus in a set of rivers (Western France).

Science.gov (United States)

Legeay, Pierre-Louis; Moatar, Florentina; Gascuel-Odoux, Chantal; Gruau, Gérard

2015-04-01

In intensive agricultural regions with important livestock farming, long-term land application of Phosphorus (P) both as chemical fertilizer and animal wastes, have resulted in elevated P contents in soils. Since we know that high P concentrations in rivers is of major concern, few studies have been done at to assess the spatiotemporal variability of P loads in rivers and apportionment of point and nonpoint source in total loads. Here we focus on Brittany (Western France) where even though P is a great issue in terms of human and drinking water safety (cyano-toxins), environmental protection and economic costs for Brittany with regards to the periodic proliferations of cyanobacteria that occur every year in this region, no regional-scale systematic study has been carried out so far. We selected a set of small rivers (stream order 3-5) with homogeneous agriculture and granitic catchment. By gathering data from three water quality monitoring networks, covering more than 100 measurements stations, we provide a regional-scale quantification of the spatiotemporal variability of dissolved P (DP) and total P (TP) interannual loads from 1992 to 2012. Build on mean P load in low flows and statistical significance tests, we developed a new indicator, called 'low flow P load' (LFP-load), which allows us to determine the importance of domestic and industrial P sources in total P load and to assess their spatiotemporal variability compared to agricultural sources. The calculation and the map representation of DP and TP interannual load variations allow identification of the greatest and lowest P contributory catchments over the study period and the way P loads of Brittany rivers have evolved through time. Both mean DP and TP loads have been divided by more than two over the last 20 years. Mean LFDP-load decreased by more than 60% and mean LFTP-load by more than 45% on average over the same period showing that this marked temporal decrease in total load is largely due to the

Adsorption of sulfamethoxazole and sulfapyridine antibiotics in high organic content soils.

Science.gov (United States)

Chen, Kuen-Lin; Liu, Li-Chun; Chen, Wan-Ru

2017-12-01

Many antibiotics, including sulfonamides, are being frequently detected in soil and groundwater. Livestock waste is an important source of antibiotic pollution, and sulfonamides may be present along with organic-rich substances. This study aims to investigate the sorption reaction of two sulfonamides, sulfamethoxazole (SMZ) and sulfapyridine (SPY) in two organic-rich sorbents: a commercial peat soil (38.41% carbon content) and a composted manure (24.33% carbon content). Batch reactions were conducted to evaluate the impacts of pH (4.5-9.5) and background ions (0.001 M-0.1 M CaCl 2 ) on their sorption. Both linear partitioning and Freundlich sorption isotherms fit the reaction well. The n values of Freundlich isotherm were close to 1 in most conditions suggesting that the hydrophobic partition is the major adsorption mechanism. In terms of SMZ, K d declined with increases in the pH. SPY has a pyridine group that is responsible for adsorption at high pH values, and thus, no significant trend between K d and pH was observed. At high pH ranges, SPY sorption deviated significantly from linear partitioning. The results suggested the sorption mechanism of these two sulfonamide antibiotics tended to be hydrophobic partitioning under most of the experimental conditions, especially at pH values lower than their corresponding pK a2. The fluorescence excitation emission matrix and dissolved organic carbon leaching test suggested composted manure has higher fulvic acid organics and that peat soil has higher humus-like organics. Small organic molecules showed stronger affinity toward sulfonamide antibiotics and cause the composted manure to exhibit higher sorption capacity. Overall, this study suggests that the chemical structure and properties of sulfonamides antibiotics and the type of organic matter in soils will greatly influence the fate and transport of these contaminants into the environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Differential Ability of Maize and Soybean to Acquire and Utilize Phosphorus from Sparingly Soluble Forms in Low- and Medium-P Soils Using {sup 32}P

Energy Technology Data Exchange (ETDEWEB)

Adu-Gyamfi, J. J.; Aigner, M.; Linic, S. [Soil and Water Management and Crop Nutrition Laboratory, Seibersdorf (Austria); Gludovacz, D. [Nuclear Material Laboratory, Safeguard Analytical Services, International Atomic Energy Agency, Seibersdorf (Austria)

2013-11-15

A glasshouse pot experiment was conducted to evaluate the differential ability of maize (Zea mays) and soybean (Glycine max) to utilize soil phosphorus (P) for plant growth from total-P, available-P and inorganic (Ca-P, Al-P and Fe-P) soil P pools using a carrier-free {sup 32}P solution. A maize variety (DK 315) and a soybean variety (TGX 1910-4F) were grown in pots containing 1 kg of a low available P soil (Hungarian) or a medium available P (Waldviertel) soil labelled with {sup 32}P for 42 days or without {sup 32}P (unlabelled) for 42 and 60 days. The shoot and root biomass of maize and soybean were significantly greater when grown on the Waldviertel than on the Hungarian soils. The shoot P concentrations were higher for soybean (1.7-2.2 g kg{sup -1}) than for maize (1.1-1.4 g kg{sup -1}). The total radioactivity (dpm x 10{sup 6}) was higher in plants grown in Waldviertel than in Hungarian soil and the values reflected plant P uptake and shoot biomass of soybean and maize. The L-values ({mu}g P g soil{sup -1}) of maize and soybean were higher in Waldviertel (72-78) than in Hungarian (9.6-20) soil. No significant differences in L-values were observed for maize and soybean grown on the Waldviertel soil, but for the Hungarian soil, the L-values were higher for maize (20.0) than for soybean (9.6) suggesting that in this low-P soil, maize was more efficient than soybean in taking up soil P. The available P (Bray II) and the Ca-P were the fractions most depleted by plants followed by the Fe-P fractions in the two soils, but differences between the crops were not significant. When soil P is limited, maize and soybean are able to access P mainly from the available P (Bray II), Fe- and Ca-P sparingly soluble fractions and not Al-P from the soil. (author)

The behavior of P in tropical soils

International Nuclear Information System (INIS)

Bittencourt, V.C.; Zambello Junior, E.

1975-06-01

The 32 P isotopic exchange between the equilibrium solution and the soil can be described by 2 or 3 first order reactions, which are mainly determined by the iron oxide content of the samples. The first reaction in Terra Roxa Estruturada and in Latosol Roxo soils was found to be independent of the ionic strength of the solution and this may be atributed to a chemical adsorption of the phosphate in the solid phase surface, with an ulterior occlusion of the ion in the internal layers. Since the constant rates of the second and third reactions was found to depend on the ionic strength of the solution and after these interactions a considerable amount of isotopic exchangeable P was observed, it is suggested that 2 phosphate diffusion processes occur: One from the hydratation shell to the solid surface and the other the equilibrium solution to the hydratation shell. The reactions in the Latosol Vermelho Escuro-fase arenosa and in the Podzolizados de Lins e Marilia, variacao Lins, soils were more intense in the liquid phase, and therefore less amounts of phosphate was subject to chemical adsorption

Retention of available P in acid soils of tropical and subtropical evergreen broad-leaved forests

Institute of Scientific and Technical Information of China (English)

CHEN Jianhui; ZOU Xiaoming; YANG Xiaodong

2007-01-01

Precipitation of mineral phosphate is often recognized as a factor of limiting the availability of P in acidic soils of tropical and subtropical forests.For this paper,we studied the extractable P pools and their transformation rates in soils of a tropical evergreen forest at Xishuangbanna and a subtropical montane wet forest at the Ailao Mountains in order to understand the biogeochemical processes regulating P availability in acidic soils.The two forests differ in forest humus layer;it is deep in the Ailao forest while little is present in the Xishuangbanna forest.The extractable P pools by resin and sodium-bicarbonate decreased when soil organic carbon content was reduced.The lowest levels of extractable P pools occurred in the surface (0-10 era) mineral soils of the Xishuangbanna forest.However,microbial P in the mineral soil of the Xishuangbauna forest was twice that in the Ailao forest.Potential rates of microbial P immobilization were greater than those of organic P mineralization in mineral soils for both forests.We suggest that microbial P immobilization plays an essential role in avoiding mineral P precipitation and retaining available P of plant in tropical acidic soils,whereas both floor mass accumulation and microbial P immobilization function benefit retaining plant available P in subtropical montane wet forests.

[Uncertainty evaluation of the determination of toxic equivalent quantity of polychlorinated dibenzo-p-dioxins and dibenzofurans in soil by isotope dilution high resolution gas chromatography and high resolution mass spectrometry].

Science.gov (United States)

Du, Bing; Liu Aimin; Huang, Yeru

2014-09-01

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in soil samples were analyzed by isotope dilution method with high resolution gas chromatography and high resolution mass spectrometry (ID-HRGC/HRMS), and the toxic equivalent quantity (TEQ) were calculated. The impacts of major source of measurement uncertainty are discussed, and the combined relative standard uncertainties were calculated for each 2, 3, 7, 8 substituted con- gener. Furthermore, the concentration, combined uncertainty and expanded uncertainty for TEQ of PCDD/Fs in a soil sample in I-TEF, WHO-1998-TEF and WHO-2005-TEF schemes are provided as an example. I-TEF, WHO-1998-TEF and WHO-2005-TEF are the evaluation schemes of toxic equivalent factor (TEF), and are all currently used to describe 2,3,7,8 sub- stituted relative potencies.

Can conservation agriculture improve phosphorus (P) availability in weathered soils? Effects of tillage and residue management on soil P status after 9 years in a Kenyan Oxisol

NARCIS (Netherlands)

Margenot, Andrew; Paul, B.K.; Pulleman, M.M.; Parikh, Sanjai; Fonte, Steven J.

2017-01-01

The widespread promotion of conservation agriculture (CA) in regions with weathered soils prone to phosphorus (P) deficiency merits explicit consideration of its effect on P availability. A long-term CA field trial located on an acid, weathered soil in western Kenya was evaluated for effects of

Characterizing Wheel-Soil Interaction Loads Using Meshfree Finite Element Methods: A Sensitivity Analysis for Design Trade Studies

Science.gov (United States)

Contreras, Michael T.; Trease, Brian P.; Bojanowski, Cezary; Kulakx, Ronald F.

2013-01-01

A wheel experiencing sinkage and slippage events poses a high risk to planetary rover missions as evidenced by the mobility challenges endured by the Mars Exploration Rover (MER) project. Current wheel design practice utilizes loads derived from a series of events in the life cycle of the rover which do not include (1) failure metrics related to wheel sinkage and slippage and (2) performance trade-offs based on grouser placement/orientation. Wheel designs are rigorously tested experimentally through a variety of drive scenarios and simulated soil environments; however, a robust simulation capability is still in development due to myriad of complex interaction phenomena that contribute to wheel sinkage and slippage conditions such as soil composition, large deformation soil behavior, wheel geometry, nonlinear contact forces, terrain irregularity, etc. For the purposes of modeling wheel sinkage and slippage at an engineering scale, meshfree nite element approaches enable simulations that capture su cient detail of wheel-soil interaction while remaining computationally feasible. This study implements the JPL wheel-soil benchmark problem in the commercial code environment utilizing the large deformation modeling capability of Smooth Particle Hydrodynamics (SPH) meshfree methods. The nominal, benchmark wheel-soil interaction model that produces numerically stable and physically realistic results is presented and simulations are shown for both wheel traverse and wheel sinkage cases. A sensitivity analysis developing the capability and framework for future ight applications is conducted to illustrate the importance of perturbations to critical material properties and parameters. Implementation of the proposed soil-wheel interaction simulation capability and associated sensitivity framework has the potential to reduce experimentation cost and improve the early stage wheel design proce

Sol–gel hybrid membranes loaded with meso/macroporous SiO2, TiO2–P2O5 and SiO2–TiO2–P2O5 materials with high proton conductivity

International Nuclear Information System (INIS)

Castro, Yolanda; Mosa, Jadra; Aparicio, Mario; Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi; Durán, Alicia

2015-01-01

In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO 2 , TiO 2 –P 2 O 5 and SiO 2 –TiO 2 –P 2 O 5 meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m 2 /g (TiO 2 –P 2 O 5 ) and 300 m 2 /g (SiO 2 –TiO 2 –P 2 O 5 ). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion ® at higher temperatures (120 °C) (2·10 −2  S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure

Interrill Erodibility of P and C on conventially and organically farmed Devon soils

Science.gov (United States)

Kuhn, N. J.

2012-04-01

Soil erosion can have significant off-site effects on water quality and thus human and habitat health. Apart from sedimentation, the transfer of nutrients, both dissolved and particulate, is a major concern. The particulate transfer of nutrients from agricultural land can occur either by rill or interrill erosion. Rill erosion is non-selective and affects only a limited extent of agricultural land. Interrill processes such as crusting, splash and raindrop-impacted wash, on the other hand, act on all cropland and affect the quality of the water from all areas generating runoff. A significant amount of phosphorus (P) is contained in the surface soil layer transformed by interrill processes annually. In the EU, the P content of a crusted (2 mm) surface layer corresponds to 4 to 40 kg ha-1 of P on arable land (1.094 mil km2). Therefore, the role of interrill processes and erosion for regional nutrient cycling requires close attention. Interrill erosion is a complex phenomenon, involving the detachment, transport and deposition of soil particles by raindrop impacted flow. Resistance to interrill erosion varies between soils depending on their physical, chemical and mineralogical properties. In addition, significant changes in soil resistance to interrill erosion occur during storms as a result of changes in surface roughness, cohesion and particle size. As a consequence, erosion on interrill areas is selective, moving the most easily detached small and/or light soil particles which are often enriched in clay, P and organic C. Commonly, the risk of erosion associated with organically farmed soils is lower than those farmed in a conventional way. This is attributed to greater aggregate stability and thus greater infiltration and lower erodibility. Erosion of nutrients on organically farmed soils is therefore considered to be reduced by the same order of magnitude than the amount of eroded soil compared to conventionally farmed soils. However, the selective nature of

Influences of micro-geomorphology on the stoichiometry of C, N and P in Chenier Island soils and plants in the Yellow River Delta, China.

Science.gov (United States)

Qu, Fanzhu; Meng, Ling; Yu, Junbao; Liu, Jingtao; Sun, Jingkuan; Yang, Hongjun; Dong, Linshui

2017-01-01

Studies have indicated that consistent or well-constrained (relatively low variability) carbon:nitrogen:phosphorus (C:N:P) ratios exist in large-scale ecosystems, including both marine and terrestrial ecosystems. Little is known about the C, N and P stoichiometric ratios that exist in the soils and plants of Chenier Island in the Yellow River Delta (YRD). We examined the distribution patterns and relationships of C, N and P stoichiometry in the soils and plants of Chenier Island, as well as the potential influences of the island's micro-geomorphology. Based on a study of four soil profile categories and Phragmites australis and Suaeda heteroptera plant tissues, our results showed that micro-geomorphology could leave a distinct imprint on the soil and plant elemental stoichiometry of Chenier Island; significant variation in the atomic C:N:P ratios (RCNP) existed in soils and plants, indicating that the RCNP values in both the soil and plants are not well constrained at the Chenier Island scale. RCN and RCP in Chenier Island soils were high, whereas the RNP values were comparatively low, indicating that the ecosystems of Chenier Island are nutrient-limited by N and P. However, the RNP values in P. australis and S. heteroptera plant tissues were high, suggesting that the plants of Chenier Island are nutrient-limited by P. Finally, we suggest that soil and plant N:P ratios may be good indicators of the soil and plant nutrient status during soil development and plant growth, which could be a useful reference for restoring the degraded soils of Chenier Island.

Availability of rock phosphate with low P content in some Albanian soil: use of /sup 32/PO/sub 4/

Energy Technology Data Exchange (ETDEWEB)

Fardeau, J C; Migadel, F; Gjermani, A; Malja, S

1983-10-01

The availability of a calcareous low P content rock phosphate (4,3% P) was measured. This Albanian ore was used, in pot experiments, on various local soils whose pH is situated between 4,9 to 7,5. This phosphate was labelled with /sup 32/P and /sup 45/Ca in a reactor. The residual effect of this fertilizer was deduced from the results of isotopic dilution kinetics of phosphate ions realized in soil-solution systems. The main results can be summarized as follows: 1. When the soil-water pH was higher than 6,1, the utilization coefficient of phosphorus was minus than 1%, even with 5,5 months. 2. The ratio of P and Ca derived from fertilizer and taken up by the crop is most generally different of those measured in the fertilizer. It depends on the soil constitution. 3. The analysis of isotopic dilution kinetics of phosphate ions shows that in the major part of these soils, whose fixing capacity is very high, the rock phosphate and also superphosphate at 230 kg P/sub 2/O/sub 5/.ha/sup -1/ rate does not increase available soil phosphorus; it is only with rates over 800 kg P/sub 2/O/sub 5/.ha/sup -1/ that this objective can be reached. These results explain again that the fixing capacity of soil for phosphorus is a characteristic more useful for fertilization technique than the available phosphorus quantity.

Seasonal Belowground Ecosystem and Eco-enzymatic Responses to Soil pH and Phosphorus Availability in Temperate Hardwood Forests

Science.gov (United States)

Smemo, K. A.; Deforest, J. L.; Petersen, S. L.; Burke, D.; Hewins, C.; Kluber, L. A.; Kyker, S. R.

2013-12-01

all enzymes measured. Phosphatase enzymes did not respond to our treatments and were generally greatest in the unglaciated soils, particularly in winter and spring. Enzyme stoichiometric relationships revealed that soil microbial populations in the glaciated site were consistently less P and N-limited than unglaciated sites but this difference was less pronounced during the growing season. The trajectory of nutrient limitation in response to soil pH and P availability was highly variable, but we observed that enzyme ratios in the early summer were particularly shifted relative to other seasons suggesting that both sites were increasingly P and N-limited during this period. Overall, our results suggest that ecosystem and microbial responses to soil pH and P availability vary with both season and site history and that more spatially and temporally explicit observations are needed to improve our understanding of ecosystem acidification, nutrient limitation, and the cost-benefit relationships of microbial investments in extracellular enzymes.

Aging of nickel added to soils as predicted by soil pH and time.

Science.gov (United States)

Ma, Yibing; Lombi, Enzo; McLaughlin, Mike J; Oliver, Ian W; Nolan, Annette L; Oorts, Koen; Smolders, Erik

2013-08-01

Although aging processes are important in risk assessment for metals in soils, the aging of Ni added to soils has not been studied in detail. In this study, after addition of water soluble Ni to soils, the changes over time in isotopic exchangeability, total concentrations and free Ni(2+) activity in soil pore water, were investigated in 16 European soils incubated outdoors for 18 months. The results showed that after Ni addition, concentrations of Ni in soil pore water and isotopic exchangeability of Ni in soils initially decreased rapidly. This phase was followed by further decreases in the parameters measured but these occurred at slower rates. Increasing soil pH increased the rate and extent of aging reactions. Semi-mechanistic models, based on Ni precipitation/nucleation on soil surfaces and micropore diffusion, were developed and calibrated. The initial fast processes, which were attributed to precipitation/nucleation, occurred over a short time (e.g. 1h), afterwards the slow processes were most likely controlled by micropore diffusion processes. The models were validated by comparing predicted and measured Ni aging in three additional, widely differing soils aged outdoors for periods up to 15 months in different conditions. These models could be used to scale ecotoxicological data generated in short-term studies to longer aging times. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impact of soil properties on critical concentrations of cadmium, lead, copper, zinc, and mercury in soil and soil solution in view of ecotoxicological effects.

Science.gov (United States)

de Vries, Wim; Lofts, Steve; Tipping, Ed; Meili, Markus; Groenenberg, Jan E; Schütze, Gudrun

2007-01-01

Risk assessment for metals in terrestrial ecosystems, including assessments of critical loads, requires appropriate critical limits for metal concentrations in soil and soil solution. This chapter presents an overview of methodologies used to derive critical (i) reactive and total metal concentrations in soils and (ii) free metal ion and total metal concentrations in soil solution for Cd, Pb, Cu, Zn, and Hg, taking into account the effect of soil properties related to ecotoxicological effects. Most emphasis is given to the derivation of critical free and total metal concentrations in soil solution, using available NOEC soil data and transfer functions relating solid-phase and dissolved metal concentrations. This approach is based on the assumption that impacts on test organisms (plants, microorganisms, and soil invertebrates) are mainly related to the soil solution concentration (activity) and not to the soil solid-phase content. Critical Cd, Pb, Cu, Zn, and Hg concentrations in soil solution vary with pH and DOC level. The results obtained are generally comparable to those derived for surface waters based on impacts to aquatic organisms. Critical soil metal concentrations, related to the derived soil solution limits, can be described as a function of pH and organic matter and clay content, and varying about one order of magnitude between different soil types.

[Effects of soil pH on the competitive uptake of amino acids by maize and microorganisms].

Science.gov (United States)

Ma, Qing Xu; Wang, Jun; Cao, Xiao Chuang; Sun, Yan; Sun, Tao; Wu, Liang Huan

2017-07-18

Organic nitrogen can play an important role in plant growth, and soil pH changed greatly due to the over-use of chemical fertilizers, but the effects of soil pH on the competitive uptake of amino acids by plants and rhizosphere microorganisms are lack of detailed research. To study the effects of soil pH on the uptake of amino acids by maize and soil microorganisms, two soils from Hangzhou and Tieling were selected, and the soil pH was changed by the electrokinesis, then the 15 N-labeled glycine was injected to the centrifuge tube with a short-term uptake of 4 h. Soil pH had a significant effect on the shoot and root biomass, and the optimal pH for maize shoot growth was 6.48 for Hangzhou red soil, while it was 7.65 for Tieling brown soil. For Hangzhou soil, the 15 N abundance of maize shoots under pH=6.48 was significantly higher than under other treatments, and the uptake amount of 15 N-glycine was also much higher. However, the 15 N abundance of maize shoots and roots under pH=7.65 Tieling soil was significantly lower than it under pH=5.78, but the uptake amount of 15 N-glycine under pH=7.65 was much higher. The microbial biomass C was much higher in pH=6.48 Hangzhou soil, while it was much lower in pH=7.65 Tieling soil. According to the results of root uptake, root to shoot transportation, and the competition with microorganisms, we suggested that although facing the fierce competition with microorganisms, the maize grown in pH=6.48 Hangzhou soil increased the uptake of glycine by increasing its root uptake and root to shoot transportation. While in pH=7.65 Tieling soil, the activity of microorganisms was decreased, which decreased the competition with maize for glycine, and increased the uptake of glycine by maize.

Effect of soil pH on sorption of salinomycin in clay and sandy soils

African Journals Online (AJOL)

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The sorption of salinomycin to the sandy soil marginally increased as the pH decreased, while the sorption to the two .... plastic containers at room temperature for further analysis. ... The pH was adjusted eight times over 20 days to stabilize at.

High-efficiency water-loaded microwave antenna in ultra-high-frequency band

Science.gov (United States)

Gong, Zilun; Bartone, Chris; Yang, Fuyi; Yao, Jie

2018-03-01

High-index dielectrics are widely used in microwave antennas to control the radiation characteristics. Liquid water, with a high dielectric index at microwave frequency, is an interesting material to achieving tunable functionalities. Here, we demonstrate a water-loaded microwave antenna system that has high loss-tolerance and wideband tunability enabled by fluidity. Our simulation and experimental results show that the resonance frequency can be effectively tuned by the size of loading water. Furthermore, the antenna systems with water loading can achieve high radiation efficiency (>90%) in the ultra-high-frequency (0.3-3 GHz) band. This work brings about opportunities in realistic tunable microwave antenna designs enabled by liquid.

The effects of H2SO4 and (NH42SO4 treatments on the chemistry of soil drainage water and pine seedlings in forest soil microcosms

Directory of Open Access Journals (Sweden)

M. I. Stutter

2004-01-01

Full Text Available An experiment comparing effects of sulphuric acid and reduced N deposition on soil water quality and on chemical and physical growth indicators for forest ecosystems is described. Six H2SO4 and (NH42SO4 treatment loads, from 0 – 44 and 0 – 25 kmolc ha-1 yr-1, respectively, were applied to outdoor microcosms of Pinus sylvestris seedlings in 3 acid to intermediate upland soils (calc-silicate, quartzite and granite for 2 years. Different soil types responded similarly to H2SO4 loads, resulting in decreased leachate pH, but differently to reduced N inputs. In microcosms of calc-silicate soil, nitrification of NH4 resulted in lower pH and higher cation leaching than in acid treatments. By contrast, in quartzite and granite soils, (NH42SO4 promoted direct cation leaching, although leachate pH increased. The results highlighted the importance of soil composition on the nature of the cations leached, the SO4 adsorption capacities and microbial N transformations. Greater seedling growth on calc-silicate soils under both treatment types was related to sustained nutrient availability. Reductions in foliar P and Mg with higher N treatments were observed for seedlings in the calc-silicate soil. There were few treatment effects on quartzite and granite microcosm tree seedlings since P limitation precluded seedling growth responses to treatments. Hence, any benefits of N deposition to seedlings on quartzite and granite soils appeared limited by availability of co-nutrients, exacerbated by rapid depletion of soil exchangeable base cations. Keywords: acidification, manipulation, nitrogen, ammonium, deposition, soil, drainage, pine, microcosms, forest

EDGA amendment of slightly heavy metal loaded soil affects heavy metal solubility, crop growth and microbivorous nematodes but not bacteria and herbivorous nematodes

NARCIS (Netherlands)

Bouwman, L.A.; Bloem, J.; Römkens, P.F.A.M.; Japenga, J.

2005-01-01

Phytoextraction of heavy metals is a promising technology to remediate slightly and moderately contaminated soils. To enhance crops' uptake of heavy metals, chelates such as EDGA are being tested as soil additives. Heavy metal loaded EDGA can affect soil organisms such as bacteria and nematodes in

Microbial N and P mining regulates the effect of N deposition on soil organic matter turnover

Science.gov (United States)

Meyer, Nele; Welp, Gerhard; Rodionov, Andrei; Borchard, Nils; Martius, Christopher; Amelung, Wulf

2017-04-01

-fertilized treatments. Nutrient additions had no effect on cumulative CO2 evolution in tropical topsoils. Subsoils of the tropical sites (20 - 100 cm depth) were co-limited by N and P. Here, alleviation of either N or P deficiency was necessary to stimulate the mineralization of glucose. In the deep subsoil (>150 cm depth) only the combined additions of N+P induced any CO2 release. Our results reveal that mining of both N and P potentially occurs but is restricted by multiple nutrient limitations, by the absence of potentially accessible nutrients (e.g., in the deep subsoil), and by full nutrient supply (e.g., high nutrient contents make mining unnecessary). The results suggest several implications for N deposition effects: 1) N deposition decreases (recalcitrant) SOC mineralization in former N-deficient soils, 2) N deposition increases SOC mineralization in former co-limited soils as it facilitates mining of the required P, 3) N deposition has no effect in nutrient rich topsoils.

Estimated environmental loads of alpha-amylase from transgenic high-amylase maize

Energy Technology Data Exchange (ETDEWEB)

Wolt, Jeffrey D. [Department of Agronomy, Iowa State University, Ames, IA 50011 (United States); Biosafety Institute for Genetically Modified Agricultural Products, 164 Seed Science, Iowa State University, Ames, IA 50011 (United States); Karaman, Sule [Biosafety Institute for Genetically Modified Agricultural Products, 164 Seed Science, Iowa State University, Ames, IA 50011 (United States)

2007-11-15

Environmental exposure of plants bioengineered to improve efficiencies of biofuel production is an important consideration for their adoption. High-amylase maize genetically engineered to produce thermostable alpha-amylase in seed endosperm is currently in development, and its successful adoption will entail >1000 km{sup 2} of annual production in the USA. Environmental exposure of thermostable amylase will occur in production fields from preharvest and harvest dropped grain, with minor additional contributions from stover and root biomass. Mass loadings of thermostable alpha-amylase are projected to be 16 kg km{sup -2} and represent a potential source of increased alpha-amylase activity in receiving soils. An understanding of the degradation, persistence, accumulation, and activity of thermostable alpha-amylase introduced from transgenic high-amylase maize will be necessary in order to effectively manage transgenic crop systems intended or biofeedstock production. (author)

Zinc fractionation in contaminated soils by sequential and single extractions: influence of soil properties and zinc content.

Science.gov (United States)

Voegelin, Andreas; Tokpa, Gerome; Jacquat, Olivier; Barmettler, Kurt; Kretzschmar, Ruben

2008-01-01

We studied the fractionation of zinc (Zn) in 49 contaminated soils as influenced by Zn content and soil properties using a seven-step sequential extraction procedure (F1: NH4NO3; F2: NH4-acetate, pH 6; F3: NH3OHCl, pH 6; F4: NH4-EDTA, pH 4.6; F5: NH4-oxalate, pH 3; F6: NH4-oxalate/ascorbic acid, pH 3; F7: residual). The soils had developed from different geologic materials and covered a wide range in soil pH (4.0-7.3), organic C content (9.3-102 g kg(-1)), and clay content (38-451 g kg(-1)). Input of aqueous Zn with runoff water from electricity towers during 26 to 74 yr resulted in total soil Zn contents of 3.8 to 460 mmol kg(-1). In acidic soils (n = 24; pH soils (n = 25; pH > or =6.0), most Zn was extracted in the mobilizable fraction (F2) and the intermediate fractions (F4 and F5). The extractability of Zn increased with increasing Zn contamination of the soils. The sum of mobile (F1) and mobilizable (F2) Zn was independent of soil pH, the ratio of Zn in F1 over F1+F2 plotted against soil pH, exhibited the typical shape of a pH sorption edge and markedly increased from pH 6 to pH 5, reflecting the increasing lability of mobilizable Zn with decreasing soil pH. In conclusion, the extractability of Zn from soils contaminated with aqueous Zn after decades of aging under field conditions systematically varied with soil pH and Zn content. The same trends are expected to apply to aqueous Zn released from decomposing Zn-bearing contaminants, such as sewage sludge or smelter slag. The systematic trends in Zn fractionation with varying soil pH and Zn content indicate the paramount effect of these two factors on molecular scale Zn speciation. Further research is required to characterize the link between the fractionation and speciation of Zn and to determine how Zn loading and soil physicochemical properties affect Zn speciation in soils.

pH is the primary determinant of the bacterial community structure in agricultural soils impacted by polycyclic aromatic hydrocarbon pollution

Science.gov (United States)

Wu, Yucheng; Zeng, Jun; Zhu, Qinghe; Zhang, Zhenfa; Lin, Xiangui

2017-01-01

Acidification and pollution are two major threats to agricultural ecosystems; however, microbial community responses to co-existed soil acidification and pollution remain less explored. In this study, arable soils of broad pH (4.26-8.43) and polycyclic aromatic hydrocarbon (PAH) gradients (0.18-20.68 mg kg-1) were collected from vegetable farmlands. Bacterial community characteristics including abundance, diversity and composition were revealed by quantitative PCR and high-throughput sequencing. The bacterial 16S rRNA gene copies significantly correlated with soil carbon and nitrogen contents, suggesting the control of nutrients accessibility on bacterial abundance. The bacterial diversity was strongly related to soil pH, with higher diversity in neutral samples and lower in acidic samples. Soil pH was also identified by an ordination analysis as important factor shaping bacterial community composition. The relative abundances of some dominant phyla varied along the pH gradient, and the enrichment of a few phylotypes suggested their adaptation to low pH condition. In contrast, at the current pollution level, PAH showed marginal effects on soil bacterial community. Overall, these findings suggest pH was the primary determinant of bacterial community in these arable soils, indicative of a more substantial influence of acidification than PAH pollution on bacteria driven ecological processes.

Labile pools of Pb in vegetable-growing soils investigated by an isotope dilution method and its influence on soil pH.

Science.gov (United States)

Xie, Hong; Huang, Zhi-Yong; Cao, Ying-Lan; Cai, Chao; Zeng, Xiang-Cheng; Li, Jian

2012-08-01

Pollution of Pb in the surface of agricultural soils is of increasing concern due to its serious impact on the plant growth and the human health through the food chain. However, the mobility, activity and bioavailability of Pb rely mainly on its various chemical species in soils. In the present study, E and L values, the labile pools of isotopically exchangeable Pb, were estimated using the method of isotope dilution in three vegetable-growing soils. The experiments involved adding a stable enriched isotope ((206)Pb > 96%) to a soil suspension and to soils in which plants are subsequently grown, the labile pools of Pb were then estimated by measuring the isotopic composition of Pb in soil solutions and in the plant tissues, respectively. In addition, the correlation of E values and soil pH was investigated at the ranges of pH 4.5-7.0. The amount of labile Pb in soils was also estimated using different single chemical extractants and a modified BCR approach. The results showed that after spiking the enriched isotopes of (206)Pb (>96%) for 24 hours an equilibration of isotopic exchanges in soil suspensions was achieved, and the isotope ratios of (208)Pb/(206)Pb measured at that time was used for calculating the E(24 h) values. The labile pools of Pb by %E(24 h) values, ranging from 53.2% to 61.7% with an average 57%, were found to be significantly higher (p soil pH was found in the tested soil sample. The results indicate that the %E(24 h) value can more rapidly and easily predict the labile pools of Pb in soils compared with L values, but it might be readily overestimated because of the artificial soil acidity derived from the spiked isotopic tracer and the excess of spiked enriched isotopes. The results also suggest that the amounts of Pb extracted with EDTA and the Σ(BCR) values extracted with the modified BCR approach are helpful to detect the labile pools of Pb in soils. In addition, the negative correlation between soil pH and the labile pools of Pb in soils

Studies on Pounding Response Considering Structure-Soil-Structure Interaction under Seismic Loads

Directory of Open Access Journals (Sweden)

Peizhen Li

2017-12-01

Full Text Available Pounding phenomena considering structure–soil–structure interaction (SSSI under seismic loads are investigated in this paper. Based on a practical engineering project, this work presents a three-dimensional finite element numerical simulation method using ANSYS software. According to Chinese design code, the models of adjacent shear wall structures on Shanghai soft soil with the rigid foundation, box foundation and pile foundation are built respectively. In the simulation, the Davidenkov model of the soil skeleton curve is assumed for soil behavior, and the contact elements with Kelvin model are adopted to simulate pounding phenomena between adjacent structures. Finally, the dynamic responses of adjacent structures considering the pounding and SSSI effects are analyzed. The results show that pounding phenomena may occur, indicating that the seismic separation requirement for adjacent buildings of Chinese design code may not be enough to avoid pounding effect. Pounding and SSSI effects worsen the adjacent buildings’ conditions because their acceleration and shear responses are amplified after pounding considering SSSI. These results are significant for studying the effect of pounding and SSSI phenomena on seismic responses of structures and national sustainable development, especially in earthquake prevention and disaster reduction.

The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil

Energy Technology Data Exchange (ETDEWEB)

Rastas Amofah, Lea; Maurice, Christian; Kumpiene, Jurate [Luleaa Univ. of Technology, Luleaa (Sweden). Dept. of Civil, Environmental and Natural Resources; Bhattacharya, Prosun [Royal Institute of Technology (KTH), Stockholm (Sweden). Dept. of Land and Water Resources Engineering

2011-12-15

Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20 C, 30 C and 40 C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. For all extractants, mobilisation was most efficient at elevated temperature (40 C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed

Enhancement of uranium loading on ion exchange resin from carbonate leachate by lowering pH from 8 to 6.5

International Nuclear Information System (INIS)

Otto, J.B.

1984-01-01

This paper discusses a laboratory study that shows the saturation ion-exchange loading of uranium from carbonate leachate can be doubled by lowering the pH of the leachate from 8 to 6.5. Small column and batch resin loading tests using Dowex 21K ion-exchange resin are described. The leachate contained 3,300 ppm chloride, 2,400 ppm carbonate, and 220 ppm U 3 O 8 , and had a pH of 8. Even at this rather mild salinity the saturation ion-exchange loading was found to be only about 3 to 4 lbm U 3 O 8 /cu ft resin (48 to 64 g/dm 3 ) because of competition with the chloride ion for exchange sites on the anionic resin. Lowering the pH of the leachate to 6.5 by CO 2 gas addition, however, increased loading to about 8 lbm U 3 O 8 /cu ft resin (128 g/dm 3 ). The pH-lowering effect worked especially well at relatively high salt concentration. The same leachate, with its chloride content increased to 12,000 ppm, loaded only 0.5 lbm U 3 O 8 /cu ft resin (8 g/dm 3 ) at pH 8 but loaded 5.5 lbm U 3 O 8 /cu ft resin (88 g/dm 3 ) at pH 6.5

Soil sterilization affects aging-related sequestration and bioavailability of p,p'-DDE and anthracene to earthworms

Energy Technology Data Exchange (ETDEWEB)

Slizovskiy, Ilya B. [Program in Environmental Science and Department of Chemistry, Muhlenberg College, Allentown, PA 18104 (United States); Kelsey, Jason W., E-mail: Kelsey@muhlenberg.ed [Program in Environmental Science and Department of Chemistry, Muhlenberg College, Allentown, PA 18104 (United States)

2010-10-15

Laboratory experiments investigated the effects of soil sterilization and compound aging on the bioaccumulation of spiked p,p'-DDE and anthracene by Eisenia fetida and Lumbricus terrestris. Declines in bioavailability occurred as pollutant residence time in both sterile and non-sterile soils increased from 3 to 203 d. Accumulation was generally higher in sterile soils during initial periods of aging (from 3-103 d). By 203 d, however, bioavailability of the compounds was unaffected by sterilization. Gamma irradiation and autoclaving may have altered bioavailability by inducing changes in the chemistry of soil organic matter (SOM). The results support a dual-mode partitioning sorption model in which the SOM components associated with short-term sorption (the 'soft' or 'rubbery' phases) are more affected than are the components associated with long-term sorption (the 'glassy' or microcrystalline phases). Risk assessments based on data from experiments in which sterile soil was used could overestimate exposure and bioaccumulation of pollutants. - Soil sterilization affects aging-related sequestration of organic contaminants.

Effects of a copper-tolerant grass (Agrostis capillaris) on the ecosystem of a copper-contaminated arable soil

Energy Technology Data Exchange (ETDEWEB)

Boon, G.T. [State Univ. Groningen (Netherlands); Bouwman, L.A.; Bloem, J.; Roemkens, P.F.A.M. [Research Inst. for Agrobiology and Soil Fertility, Haren (Netherlands)

1998-10-01

To test how a dysfunctioning ecosystem of a severely metal-polluted soil responds to renewed plant growth, a pot experiment was conducted with soil from an experimental arable field with pH and copper gradients imposed 13 years ago. In this experiment, four pH/copper combinations from this field were either planted with a pH- and copper-resistant grass cultivar or remained fallow. During a 10-week period, the dynamics of the microbial activity and of the abundances of bacteria, protozoa. and nematodes were measured, as were the dynamics of several chemical soil parameters. After 13 years of copper, which had resulted in severely reduced crop growth, no effects were observed on bacterial numbers, respiration, or protozoan numbers, but bacterial growth was strongly reduced in the low pH plots, and even more so in low pH plots enriched with copper. Of the organisms, only nematodes were negatively affected under conditions of high copper load at low pH. In these plots, numbers belonging to all feeding categories were strongly reduced. Planting of a copper-tolerant grass variety, Agrostis capillaris L. var. Parys Mountain, resulted within 10 weeks in faster bacterial growth and more protozoa and bacterivorous nematodes in comparison with fallow controls; these effects were markedly strongest in the acidic, copper-enriched soils. During incubation, fungivorous nematodes increased in all treatments, in fallow and in planted pots and in the pots with high-copper, low-pH soil. The results of this experiment suggest that introduction of plant growth is one of the major causes of increased biological activity in acidic contaminated soils. Planting such soils with metal-tolerant plant species can reestablish the necessary food base to support soil organism growth, and this can lead to numerous positive effects, reversing the loss of soil functions due to the high copper levels under acidic conditions.

Sensitivity Analysis of the Agricultural Policy/Environmental eXtender (APEX) for Phosphorus Loads in Tile-Drained Landscapes.

Science.gov (United States)

Ford, W; King, K; Williams, M; Williams, J; Fausey, N

2015-07-01

Numerical modeling is an economical and feasible approach for quantifying the effects of best management practices on dissolved reactive phosphorus (DRP) loadings from agricultural fields. However, tools that simulate both surface and subsurface DRP pathways are limited and have not been robustly evaluated in tile-drained landscapes. The objectives of this study were to test the ability of the Agricultural Policy/Environmental eXtender (APEX), a widely used field-scale model, to simulate surface and tile P loadings over management, hydrologic, biologic, tile, and soil gradients and to better understand the behavior of P delivery at the edge-of-field in tile-drained midwestern landscapes. To do this, a global, variance-based sensitivity analysis was performed, and model outputs were compared with measured P loads obtained from 14 surface and subsurface edge-of-field sites across central and northwestern Ohio. Results of the sensitivity analysis showed that response variables for DRP were highly sensitive to coupled interactions between presumed important parameters, suggesting nonlinearity of DRP delivery at the edge-of-field. Comparison of model results to edge-of-field data showcased the ability of APEX to simulate surface and subsurface runoff and the associated DRP loading at monthly to annual timescales; however, some high DRP concentrations and fluxes were not reflected in the model, suggesting the presence of preferential flow. Results from this study provide new insights into baseline tile DRP loadings that exceed thresholds for algal proliferation. Further, negative feedbacks between surface and subsurface DRP delivery suggest caution is needed when implementing DRP-based best management practices designed for a specific flow pathway. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Shifting Foliar N:P Ratios with Experimental Soil Warming in Tussock Tundra

Science.gov (United States)

Jasinski, B.; Mack, M. C.; Schuur, E.; Mauritz, M.; Walker, X. J.

2017-12-01

Warming temperatures in the Arctic and boreal ecosystems are currently driving widespread permafrost thaw. Thermokarst is one form of thaw, in which a deepening active soil layer and associated hydrologic changes can lead to increased nutrient availability and shifts in plant community composition. Individual plant species often differ in their ability to access nutrients and adapt to new environmental conditions. While nitrogen (N) is often the nutrient most limiting to Arctic plant communities, the extent to which plant available phosphorus (P) from previously frozen mineral soil may increase as the active layer deepens is still uncertain. To understand the changing relationship between species' uptake of N and P in a thermokarst environment, we assessed foliar N:P ratios from 2015 in two species, a tussock sedge (Eriophorum vaginatum) and a dwarf shrub (Rubus chamaemorus), at a moist acidic tussock tundra experimental passive soil warming site. The passive soil warming treatment increased active layer depth in warmed plots by 35.4 cm (+/- 1.1 cm), an 80% increase over the control plots. E.vaginatum demonstrated a 16.9% decrease (p=0.012, 95% CI [-27.99%, -5.94%]) in foliar N:P ratios in warmed plots, driven mostly by an increase in foliar phosphorus. Foliar N:P ratios of R.chamaemorus showed no significant change. However, foliar samples of R.chamaemorus were significantly enriched in the isotope 15N in soil warming plots (9.9% increase (p=0.002, 95% CI [4.45%, 15.39%])), while the sedge E.vaginatum was slightly depleted. These results suggest that (1) in environments with thawing mineral soil plant available phosphorus may increase more quickly than nitrogen, and (2) that species' uptake strategies and responses to increasing N and P will vary, which has implications for future ecological shifts in thawing ecosystems.

Lead, zinc and pHconcentrationsof Enyigba soils in Abakaliki Local ...

African Journals Online (AJOL)

STORAGESEVER

2008-07-18

Jul 18, 2008 ... Abakaliki Local Government Area of Ebonyi State,. Nigeria. F. N. Nweke1 ... establish a base line pollution index for lead and zinc in Enyigba soil as an exogenous source of these .... is done to reduce the pH value of the soil.

Effect of heavy metals on pH buffering capacity and solubility of Ca, Mg, K, and P in non-spiked and heavy metal-spiked soils.

Science.gov (United States)

Najafi, Sarvenaz; Jalali, Mohsen

2016-06-01

In many parts of the world, soil acidification and heavy metal contamination has become a serious concern due to the adverse effects on chemical properties of soil and crop yield. The aim of this study was to investigate the effect of pH (in the range of 1 to 3 units above and below the native pH of soils) on calcium (Ca), magnesium (Mg), potassium (K), and phosphorus (P) solubility in non-spiked and heavy metal-spiked soil samples. Spiked samples were prepared by cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) as chloride salts and incubating soils for 40 days. The pH buffering capacity (pHBC) of each sample was determined by plotting the amount of H(+) or OH(-) added (mmol kg(-1)) versus the related pH value. The pHBC of soils ranged from 47.1 to 1302.5 mmol kg(-1) for non-spiked samples and from 45.0 to 1187.4 mmol kg(-1) for spiked soil samples. The pHBC values were higher in soil 2 (non-spiked and spiked) which had higher calcium carbonate content. The results indicated the presence of heavy metals in soils generally decreased the solution pH and pHBC values in spiked samples. In general, solubility of Ca, Mg, and K decreased with increasing equilibrium pH of non-spiked and spiked soil samples. In the case of P, increasing the pH to about 7, decreased the solubility in all soils but further increase of pH from 7, enhanced P solubility. The solubility trends and values for Ca, Mg, and K did not differed significantly in non-spiked and spiked samples. But in the case of P, a reduction in solubility was observed in heavy metal-spiked soils. The information obtained in this study can be useful to make better estimation of the effects of soil pollutants on anion and cation solubility from agricultural and environmental viewpoints.

A statistically based mapping of the influence of geology and land use on soil pH

DEFF Research Database (Denmark)

Balstrøm, Thomas; Breuning-Madsen, Henrik; Krüger, Johannes

2013-01-01

. The data have been analysed using statistical spatial analysis methods, and a model has been erected demonstrating areas of homogeneous low, high, or inhomogeneous pH values relative to deposits from different ice advances and regional variations in land use. The investigation shows that the major part......The purpose of this paper is to investigate the geographical distribution of pH values in Danish soils of different ages representing the main Saalian and Weichselian ice advances. The investigation is based on soil sampling from top- and subsoils in soil profiles located in a nationwide 7-km grid...... of Jutland is characterized by low pH values in the topsoils and subsoils compared to the islands east of the peninsula. This corresponds with the maximum extension of the Weichselian Young Baltic Ice Cap. A Hot Spot analysis carried out on regional and local scales shows that most of the Danish islands form...

Soil mixing design methods and construction techniques for use in high organic soils.

Science.gov (United States)

2015-06-01

Organic soils present a difficult challenge for roadway designers and construction due to the high : compressibility of the soil structure and the often associated high water table and moisture content. For : other soft or loose inorganic soils, stab...

Baseline geochemistry of soil and bedrock Tshirege Member of the Bandelier Tuff at MDA-P

International Nuclear Information System (INIS)

Warren, R.G.; McDonald, E.V.; Ryti, R.T.

1997-08-01

This report provides baseline geochemistry for soils (including fill), and for bedrock within three specific areas that are planned for use in the remediation of Material Disposal Area P (MDA-P) at Technical Area 16 (TA-16). The baseline chemistry includes leachable element concentrations for both soils and bedrock and total element concentrations for all soil samples and for two selected bedrock samples. MDA-P operated from the early 1950s to 1984 as a landfill for rubble and debris generated by the burning of high explosives (HE) at the TA-16 Burning Ground, HE-contaminated equipment and material, barium nitrate sand, building materials, and trash. The aim of this report is to establish causes for recognizable chemical differences between the background and baseline data sets. In many cases, the authors conclude that recognizable differences represent natural enrichments. In other cases, differences are best attributed to analytical problems. But most importantly, the comparison of background and baseline geochemistry demonstrates significant contamination for several elements not only at the two remedial sites near the TA-16 Burning Ground, but also within the entire region of the background study. This contamination is highly localized very near to the surface in soil and fill, and probably also in bedrock; consequently, upper tolerance limits (UTLs) calculated as upper 95% confidence limits of the 95th percentile are of little value and thus are not provided. This report instead provides basic statistical summaries and graphical comparisons for background and baseline samples to guide strategies for remediation of the three sites to be used in the restoration of MDA-P

Decomposition of benzidine, α-naphthylamine, and p-toluidine in soils

International Nuclear Information System (INIS)

Graveel, J.G.; Sommers, L.E.; Nelson, D.W.

1986-01-01

Decomposition of 14 C-labeled benzidine, α-naphthylamine, and p-toluidine in soil was studied in laboratory experiments by monitoring CO 2 production during a 308- to 365-d incubation period. The importance of microbial activity in decomposition of all three aromatic amines was shown by decreased 14 CO 2 evolution in 60 Co treated soils. After 365 d of incubation, 8.4 to 12% of added benzidine (54.3 μmol kg -1 ) was evolved as CO 2 while 17 to 31% of added α-naphthylamine (69.8 μmol kg -1 ) and 19 to 35% of added p-toluidine (93.3 μmol kg -1 ) were evolved as CO 2 in 308 d. Decomposition was enhanced by increasing the temperature from 12 to 30 0 C. For benzidine, both the amount and proportion decomposed increased with an increase in application rate. Decomposition of aromatic amines was not enhanced by the addition of decomposable substrates. Differences in decomposition of aromatic amines occurred among soils, but consistent relationships between decomposition of amines and soil properties were not observed. In batch equilibration studies, the Freundlich equation described aromatic amine sorption. Isotherms were nonlinear for benzidine and 1 -naphthylamine and linear for p-toluidine. Desorption of sorbed amines followed the order: benzidine < p-toluidine < α-naphthylamine and was inversely related to the extent of decomposition

Stabilisation of clayey soils with high calcium fly ash and cement

Energy Technology Data Exchange (ETDEWEB)

S. Kolias; V. Kasselouri-Rigopoulou; A. Karahalios [National Technical University of Athens, Athens (Greece)

2005-02-01

The effectiveness of using high calcium fly ash and cement in stabilising fine-grained clayey soils (CL,CH) was investigated in the laboratory. Strength tests in uniaxial compression, in indirect (splitting) tension and flexure were carried out on samples to which various percentages of fly ash and cement had been added. Modulus of elasticity was determined at 90 days with different types of load application and 90-day soaked CBR values are also reported. Pavement structures incorporating subgrades improved by in situ stabilisation with fly ash and cement were analyzed for construction traffic and for operating traffic. These pavements are compared with conventional flexible pavements without improved subgrades and the results clearly show the technical benefits of stabilising clayey soils with fly ash and cement. In addition TG-SDTA and XRD tests were carried out on certain samples in order to study the hydraulic compounds, which were formed.

Soil behavior under earthquake loading conditions. In situ impulse test for determination of shear modulus for seismic response analyses. Progress report

International Nuclear Information System (INIS)

1974-06-01

Progress is reported in the determination of the best methods of evaluation and prediction of soil behavior of potential nuclear power plant sites under seismic loading conditions. Results are reported of combined experimental and analytical studies undertaken to continue development of an in situ impulse test for determination of the soil shear modulus. Emphasis of the field work was directed toward making the field measurements at frequent depth intervals and at shear strains in the strong motion earthquake range. Emphasis of the analytical work was aimed toward supporting the field effort through processing and evaluation of the experimental test results combined with additional calculations required to gain insight into data interpretation and the in situ test setup itself. Continuing studies to evaluate free field soil behavior under earthquake loading conditions are discussed. (U.S.)

Experimental determinations of soil copper toxicity to lettuce (Lactuca sativa) growth in highly different copper spiked and aged soils.

Science.gov (United States)

Christiansen, Karen S; Borggaard, Ole K; Holm, Peter E; Vijver, Martina G; Hauschild, Michael Z; Peijnenburg, Willie J G M

2015-04-01

Accurate knowledge about factors and conditions determining copper (Cu) toxicity in soil is needed for predicting plant growth in various Cu-contaminated soils. Therefore, effects of Cu on growth (biomass production) of lettuce (Lactuca sativa) were tested on seven selected, very different soils spiked with Cu and aged for 2 months at 35 °C. Cu toxicity was expressed as pEC50(Cu(2+)), i.e., the negative logarithm of the EC50(Cu(2+)) activity to plant growth. The determined pEC50(Cu(2+)) was significantly and positively correlated with both the analytically readily available soil pH and concentration of dissolved organic carbon [DOC] which together could explain 87% of the pEC50(Cu(2+)) variation according to the simple equation: pEC50(Cu(2+)) = 0.98 × pH + 345 × [DOC] - 0.27. Other soil characteristics, including the base cation concentrations (Na(+), K(+), Ca(2+), Mg(2+)), the cation exchange capacity at soil pH (ECEC), and at pH 7 (CEC7), soil organic carbon, clay content, and electric conductivity as well as the distribution coefficient (Kd) calculated as the ratio between total soil Cu and water-extractable Cu did not correlate significantly with pEC50(Cu(2+)). Consequently, Cu toxicity, expressed as the negative log of the Cu(2+) activity, to plant growth increases at increasing pH and DOC, which needs to be considered in future management of plant growth on Cu-contaminated soils. The developed regression equation allows identification of soil types in which the phytotoxicity potential of Cu is highest.

Growth, Metabolism and Yield of Rice Cultivated in Soils Amended with Fly Ash and Cyanobacteria and Metal Loads in Plant Parts

Directory of Open Access Journals (Sweden)

Rabindra N. Padhy

2016-01-01

Full Text Available Soil amendment with fly ash (FA and combined supplementation with N2-fixing cyanobacteria masses as biofertilizer were done in field experiments with rice. Amendments with FA levels, 0, 0.5, 1.0, 2.0, 4.0, 8.0 and 10.0 kg/m2, caused increase in growth and yield of rice up to 8.0 kg/m2, monitored with several parameters. Pigment contents and enzyme activities of leaves were enhanced by FA, with the maximum level of FA at 10.0 kg/m2. Protein content of rice seeds was the highest in plants grown at FA level 4.0 kg/m2. Basic soil properties, pH value, percentage of silt, percentage of clay, water-holding capacity, electrical conductivity, cation exchange capacity, and organic carbon content increased due to the FA amendment. Parallel supplementation of FA amended plots with 1.0 kg/m2 N2-fixing cyanobacteria mass caused further significant increments of the most soil properties, and rice growth and yield parameters. 1000-grain weight of rice plants grown at FA level 4.0 kg/m2 along with cyanobacteria supplementation was the maximum. Cyanobacteria supplementation caused increase of important basic properties of soil including the total N-content. Estimations of elemental content in soils and plant parts (root and seed were done by the atomic absorption spectrophotometry. Accumulations of K, P, Fe and several plant micronutrients (Mn, Ni, Co, Zn and Cu and toxic elements (Pb, Cr and Cd increased in soils and plant parts as a function of the FA gradation, but Na content remained almost unchanged in soils and seeds. Supplementation of cyanobacteria had ameliorating effect on toxic metal contents of soils and plant parts. The FA level 4.0 kg/m2, with 1.0 kg/m2 cyanobacteria mass supplementation, could be taken ideal, since there would be recharging of the soil with essential micronutrients as well as toxic chemicals in comparative lesser proportions, and cyanobacteria mass would cause lessening toxic metal loads with usual N2-fixation.