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Sample records for biological soil crust

  1. Biological Soil Crust Web Site

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    www.soilcrust.org Crust 101 Advanced Gallery References CCERS site Links Biological Soil Crusts Textbook Corrections Level of Development Index Biological soil crusts are the community of organisms , mosses, liverworts and lichens. A Field Guide to Biological Soil Crusts of Western U.S. Drylands: Common

  2. Biological Soil Crusts: Webs of Life in the Desert

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    Belnap, Jayne

    2001-01-01

    Although the soil surface may look like dirt to you, it is full of living organisms that are a vital part of desert ecosystems. This veneer of life is called a biological soil crust. These crusts are found throughout the world, from hot deserts to polar regions. Crusts generally cover all soil spaces not occupied by green plants. In many areas, they comprise over 70% of the living ground cover and are key in reducing erosion, increasing water retention, and increasing soil fertility. In most dry regions, these crusts are dominated by cyanobacteria (previously called blue-green algae), which are one of the oldest known life forms. Communities of soil crusts also include lichens, mosses, microfungi, bacteria, and green algae. These living organisms and their by-products create a continuous crust on the soil surface. The general color, surface appearance, and amount of coverage of these crusts vary depending on climate and disturbance patterns. Immature crusts are generally flat and the color of the soil, which makes them difficult to distinguish from bare ground. Mature crusts, in contrast, are usually bumpy and dark-colored due to the presence of lichens, mosses, and high densities of cyanobacteria and other organisms.

  3. Biological soil crusts as an integral component of desert environments

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    Belnap, Jayne; Weber, Bettina

    2013-01-01

    The biology and ecology of biological soil crusts, a soil surface community of mosses, lichens, cyanobacteria, green algae, fungi, and bacteria, have only recently been a topic of research. Most efforts began in the western U.S. (Cameron, Harper, Rushforth, and St. Clair), Australia (Rogers), and Israel (Friedmann, Evenari, and Lange) in the late 1960s and 1970s (e.g., Friedmann et al. 1967; Evenari 1985reviewed in Harper and Marble 1988). However, these groups worked independently of each other and, in fact, were often not aware of each other’s work. In addition, biological soil crust communities were seen as more a novelty than a critical component of dryland ecosystems. Since then, researchers have investigated many different aspects of these communities and have shown that although small to microscopic, biological soil crusts are critical in many ecological processes of deserts. They often cover most of desert soil surfaces and substantially mediate inputs and outputs from desert soils (Belnap et al. 2003). They can be a large source of biodiversity for deserts, as they can contain more species than the surrounding vascular plant community (Rosentreter 1986). These communities are important in reducing soil erosion and increasing soil fertility through the capture of dust and the fixation of atmospheric nitrogen and carbon into forms available to other life forms (Elbert et al. 2012). Because of their many effects on soil characteristics, such as external and internal morphological characteristics, aggregate stability, soil moisture, and permeability, they also affect seed germination and establishment and local hydrological cycles. Covering up to 70% of the surface area in many arid and semi-arid regions around the world (Belnap and Lange 2003), biological soil crusts are a key component within desert environments.

  4. Linking biological soil crust diversity to ecological functions

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    Glaser, Karin; Borchhardt, Nadine; Schulz, Karoline; Mikhailyuk, Tatiana; Baumann, Karen; Leinweber, Peter; Ulf, Karsten

    2016-04-01

    Biological soil crusts (BSCs) are an association of different microorganisms and soil particles in the top millimeters of the soil. They are formed by algae, cyanobacteria, microfungi, bacteria, bryophytes and lichens in various compositions. Our aim was to determine and compare the biodiversity of all occurring organisms in biogeographically different habitats, ranging from polar (both Arctic and Antarctic), subpolar (Scandinavia), temperate (Germany) to dry regions (Chile). The combination of microscopy and molecular techniques (next-generation sequencing) revealed highly diverse crust communities, whose composition clustered by region and correlates with habitat characteristics such as water content. The BSC biodiversity was then linked to the ecological function of the crusts. The functional role of the BSCs in the biogeochemical cycles of carbon, nitrogen and phosphorous is evaluated using an array of state of the art soil chemistry methods including Py-FIMS (pyrolysis field ionization mass spectrometry) and XANES (x-ray absorbance near edge structure). Total P as well as P fractions were quantified in all BSCs, adjacent soil underneath and comparable nearby soil of BSC-free areas revealing a remarkable accumulation of total phosphorous and a distinct pattern of P fractions in the crust. Further, we observed an indication of a different P-speciation composition in the crust compared with BSC-free soil. The data allow answering the question whether BSCs act as sink or source for these compounds, and how biodiversity controls the biogeochemical function of BSCs.

  5. Biological soil crusts in Chile along the precipitation gradient

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    Samolov, Elena; Glaser, Karin; Baumann, Karen; Leinweber, Peter; Jung, Patrick; Büdel, Burkhard; Mikhailyuk, Tatiana; Karsten, Ulf

    2017-04-01

    Biological soil crusts in Chile along a precipitation gradient Elena Samolov* (1), Karin Glaser (1), Karen Baumann (2), Peter Leinweber (2), Patrick Jung (3), Burkhard Büdel (3), Tatiana Mikhailyuk (4) and Ulf Karsten (1) (1) Institute of Biological Sciences - Applied Ecology and Phycology, University of Rostock, Rostock, Germany, (2) Faculty of Agricultural and Environmental Sciences - Soil Sciences, University of Rostock, Rostock, Germany (3) University of Kaiserslautern, Kaiserslautern, Germany (4) M.H. Kholodny Institute of Botany, National Academy of Science of Ukraine, Kyiv, Ukraine * elena.samolov@uni-rostock.de Biological soil crusts (BSCs) are an association of different microorganisms and soil particles in the top millimeters of the soil. They are formed by algae, cyanobacteria, microfungi, bacteria, bryophytes and lichens in various compositions; together with their by-products they create a micro-ecosystem that performs important ecological functions, e.g. primary production, nitrogen fixation, mineralization and stabilization of soils. These top-soil assemblages are almost unstudied in South America (Büdel et al. 2016). Therefore, our aim is to investigate for the first time biodiversity of the key photosynthetic organisms, green algae and cyanobacteria following a precipitation gradient along the west coast of Chile. We are applying polyphasic approach - a combination of microscopy, culture dependent (16S and 18S rRNA, ITS) and culture independent molecular techniques (NGS). First results, based on culturing and light microscopy, showed high diversity of eukaryotic algae in biocrusts from humid regions, followed by semi-arid regions. Lichen dominated biocrusts from arid regions were characterized by a high diversity of green algae, while cyanobacteria were scarcely present. The functional role of the BSCs in the biogeochemical cycle of phosphorous (P) was evaluated using state of the art analytical methods including 31P-NMR (nuclear magnetic

  6. Impact of environmental factors and biological soil crust types on soil respiration in a desert ecosystem.

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    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93 ± 0.43 µmol m-2 s-1) and the lowest values in algae-crusted soil (0.73 ± 0.31 µmol m-2 s-1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m-3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level.

  7. Impact of Environmental Factors and Biological Soil Crust Types on Soil Respiration in a Desert Ecosystem

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    Feng, Wei; Zhang, Yuqing; Jia, Xin; Wu, Bin; Zha, Tianshan; Qin, Shugao; Wang, Ben; Shao, Chenxi; Liu, Jiabin; Fa, Keyu

    2014-01-01

    The responses of soil respiration to environmental conditions have been studied extensively in various ecosystems. However, little is known about the impacts of temperature and moisture on soils respiration under biological soil crusts. In this study, CO2 efflux from biologically-crusted soils was measured continuously with an automated chamber system in Ningxia, northwest China, from June to October 2012. The highest soil respiration was observed in lichen-crusted soil (0.93±0.43 µmol m−2 s−1) and the lowest values in algae-crusted soil (0.73±0.31 µmol m−2 s−1). Over the diurnal scale, soil respiration was highest in the morning whereas soil temperature was highest in the midday, which resulted in diurnal hysteresis between the two variables. In addition, the lag time between soil respiration and soil temperature was negatively correlated with the soil volumetric water content and was reduced as soil water content increased. Over the seasonal scale, daily mean nighttime soil respiration was positively correlated with soil temperature when moisture exceeded 0.075 and 0.085 m3 m−3 in lichen- and moss-crusted soil, respectively. However, moisture did not affect on soil respiration in algae-crusted soil during the study period. Daily mean nighttime soil respiration normalized by soil temperature increased with water content in lichen- and moss-crusted soil. Our results indicated that different types of biological soil crusts could affect response of soil respiration to environmental factors. There is a need to consider the spatial distribution of different types of biological soil crusts and their relative contributions to the total C budgets at the ecosystem or landscape level. PMID:25050837

  8. Don’t bust the biological soil crust: Preserving and restoring an important desert resource

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    Sue Miller; Steve Warren; Larry St. Clair

    2017-01-01

    Biological soil crusts are a complex of microscopic organisms growing on the soil surface in many arid and semi-arid ecosystems. These crusts perform the important role of stabilizing soil and reducing or eliminating water and wind erosion. One of the largest threats to biological soil crusts in the arid and semi-arid areas of the western United States is mechanical...

  9. Reconstruction of food webs in biological soil crusts using metabolomics.

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    Baran, Richard; Brodie, Eoin L.; Mayberry-Lewis, Jazmine; Nunes Da Rocha, Ulisses; Bowen, Benjamin P.; Karaoz, Ulas; Cadillo-Quiroz, Hinsby; Garcia-Pichel, Ferran; Northen, Trent R.

    2015-04-01

    Biological soil crusts (BSCs) are communities of organisms inhabiting the upper layer of soil in arid environments. BSCs persist in a dessicated dormant state for extended periods of time and experience pulsed periods of activity facilitated by infrequent rainfall. Microcoleus vaginatus, a non-diazotrophic filamentous cyanobacterium, is the key primary producer in BSCs in the Colorado Plateau and is an early pioneer in colonizing arid environments. Over decades, BSCs proceed through developmental stages with increasing complexity of constituent microorganisms and macroscopic properties. Metabolic interactions among BSC microorganisms probably play a key role in determining the community dynamics and cycling of carbon and nitrogen. However, these metabolic interactions have not been studied systematically. Towards this goal, exometabolomic analysis was performed using liquid chromatography coupled to tandem mass spectrometry on biological soil crust pore water and spent media of key soil bacterial isolates. Comparison of spent vs. fresh media was used to determine uptake or release of metabolites by specific microbes. To link pore water experiments with isolate studies, metabolite extracts of authentic soil were used as supplements for isolate exometabolomic profiling. Our soil metabolomics methods detected hundreds of metabolites from soils including many novel compounds. Overall, Microcoleus vaginatus was found to release and utilize a broad range of metabolites. Many of these metabolites were also taken up by heterotrophs but there were surprisingly few metabolites uptaken by all isolates. This points to a competition for a small set of central metabolites and specialization of individual heterotrophs towards a diverse pool of available organic nutrients. Overall, these data suggest that understanding the substrate specialization of biological soil crust bacteria can help link community structure to nutrient cycling.

  10. Synthesis on biological soil crust research

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    Weber, Bettina; Belnap, Jayne; Buedel, Burkhard

    2016-01-01

    In this closing chapter, we summarize the advances in biocrust research made during the last 1.5 decades. In the first part of the chapter, we discuss how in some research fields, such as the microbial diversity of fungi, bacteria, and microfauna; the interaction between biocrusts and vascular plants; and in the rehabilitation of biocrusts; particularly large achievements have been made. In other fields, previously established knowledge of overall patterns has been corroborated and refined by additional studies, e.g., in the fields of soil stabilization and disturbance effects. In the second part of the chapter, we outline the research gaps and challenges foreseen by us. We identify multiple knowledge gaps, including many understudied geographic regions, the largely missing link between genetic and morphological species identification data, and the answers to some mechanistic questions, such as the overall role of biocrusts in hydrology and nutrient cycles. With some ideas on promising new research questions and approaches we close this chapter and the overall book.

  11. The potential roles of biological soil crusts in dryland hydrologic cycles

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    Belnap, J.

    2006-01-01

    Biological soil crusts (BSCs) are the dominant living cover in many drylands of the world. They possess many features that can influence different aspects of local hydrologic cycles, including soil porosity, absorptivity, roughness, aggregate stability, texture, pore formation, and water retention. The influence of biological soil crusts on these factors depends on their internal and external structure, which varies with climate, soil, and disturbance history. This paper presents the different types of biological soil crusts, discusses how crust type likely influences various aspects of the hydrologic cycle, and reviews what is known and not known about the influence of biological crusts on sediment production and water infiltration versus runoff in various drylands around the world. Most studies examining the effect of biological soil crusts on local hydrology are done by comparing undisturbed sites with those recently disturbed by the researchers. Unfortunately, this greatly complicates interpretation of the results. Applied disturbances alter many soil features such as soil texture, roughness, aggregate stability, physical crusting, porosity, and bulk density in ways that would not necessarily be the same if crusts were not naturally present. Combined, these studies show little agreement on how biological crusts affect water infiltration or runoff. However, when studies are separated by biological crust type and utilize naturally occurring differences among these types, results indicate that biological crusts in hyperarid regions reduce infiltration and increase runoff, have mixed effects in and regions, and increase infiltration and reduce runoff in semiarid cool and cold drylands. However, more studies are needed before broad generalizations can be made on how biological crusts affect infiltration and runoff. We especially need studies that control for sub-surface soil features such as bulk density, micro- and macropores, and biological crust structure. Unlike

  12. Diel hysteresis between soil respiration and soil temperature in a biological soil crust covered desert ecosystem.

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    Guan, Chao; Li, Xinrong; Zhang, Peng; Chen, Yongle

    2018-01-01

    Soil respiration induced by biological soil crusts (BSCs) is an important process in the carbon (C) cycle in arid and semi-arid ecosystems, where vascular plants are restricted by the harsh environment, particularly the limited soil moisture. However, the interaction between temperature and soil respiration remains uncertain because of the number of factors that control soil respiration, including temperature and soil moisture, especially in BSC-dominated areas. In this study, the soil respiration in moss-dominated crusts and lichen-dominated crusts was continuously measured using an automated soil respiration system over a one-year period from November 2015 to October 2016 in the Shapotou region of the Tengger Desert, northern China. The results indicated that over daily cycles, the half-hourly soil respiration rates in both types of BSC-covered areas were commonly related to the soil temperature. The observed diel hysteresis between the half-hourly soil respiration rates and soil temperature in the BSC-covered areas was limited by nonlinearity loops with semielliptical shapes, and soil temperature often peaked later than the half-hourly soil respiration rates in the BSC-covered areas. The average lag times between the half-hourly soil respiration rates and soil temperature for both types of BSC-covered areas were two hours over the diel cycles, and they were negatively and linearly related to the volumetric soil water content. Our results highlight the diel hysteresis phenomenon that occurs between soil respiration rates and soil temperatures in BSC-covered areas and the negative response of this phenomenon to soil moisture, which may influence total C budget evaluations. Therefore, the interactive effects of soil temperature and moisture on soil respiration in BSC-covered areas should be considered in global carbon cycle models of desert ecosystems.

  13. Uncovering biological soil crusts: carbon content and structure of intact Arctic, Antarctic and alpine biological soil crusts

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    Jung, Patrick; Briegel-Williams, Laura; Simon, Anika; Thyssen, Anne; Büdel, Burkhard

    2018-02-01

    Arctic, Antarctic and alpine biological soil crusts (BSCs) are formed by adhesion of soil particles to exopolysaccharides (EPSs) excreted by cyanobacterial and green algal communities, the pioneers and main primary producers in these habitats. These BSCs provide and influence many ecosystem services such as soil erodibility, soil formation and nitrogen (N) and carbon (C) cycles. In cold environments degradation rates are low and BSCs continuously increase soil organic C; therefore, these soils are considered to be CO2 sinks. This work provides a novel, non-destructive and highly comparable method to investigate intact BSCs with a focus on cyanobacteria and green algae and their contribution to soil organic C. A new terminology arose, based on confocal laser scanning microscopy (CLSM) 2-D biomaps, dividing BSCs into a photosynthetic active layer (PAL) made of active photoautotrophic organisms and a photosynthetic inactive layer (PIL) harbouring remnants of cyanobacteria and green algae glued together by their remaining EPSs. By the application of CLSM image analysis (CLSM-IA) to 3-D biomaps, C coming from photosynthetic active organisms could be visualized as depth profiles with C peaks at 0.5 to 2 mm depth. Additionally, the CO2 sink character of these cold soil habitats dominated by BSCs could be highlighted, demonstrating that the first cubic centimetre of soil consists of between 7 and 17 % total organic carbon, identified by loss on ignition.

  14. Biological soil crusts: a fundamental organizing agent in global drylands

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    Belnap, J.; Zhang, Y.

    2013-12-01

    Ecosystem function is profoundly affected by plant community composition, which is ultimately determined by factors that govern seed retention. Dryland ecosystems constitute ~35% of terrestrial surfaces, with most soils in these regions covered by biological soil crusts (biocrusts), a community whose autotrophs are dominated by cyanobacteria, lichens, and mosses. Studies at 550 sites revealed that plant community composition was controlled by the interaction among biocrust type, disturbance regime, and external morphology of seeds. In bare soils (due to disturbance), all seed types were present in the seedbank and plant community. As biocrusts became better developed (i.e., the cover of lichens and mosses increased), they more strongly filtered out seeds with appendages. Thus, soils under late successional biocrusts contained seedbanks dominated by smooth seeds and vascular plants growing in late successional biocrusts were dominated by those with smooth seeds. Therefore, the tension between the removal of biocrusts by soil surface disturbance and their recovery creates a shifting mosaic of plant patch types in both space and time. Because changes in vascular plant communities reverberate throughout both below ground and above ground food webs and thus affect multiple trophic levels, we propose that biocrusts are a fundamental organizing agent in drylands worldwide. Future increased demand for resources will intensify land use both temporally and spatially, resulting in an increased rate of biocrust loss across larger areas. As a result, we can expect shifts in the composition and distribution of plant communities, accompanied by concomitant changes in many aspects of dryland ecosystems. Conceptual model of shifting dryland plant mosaics through space and time. Within the large circles, soil surface type changes with time in the same space, going from bare uncrusted soil (B) to cyanobacterial biocrust (C) to lichen/moss (L/M) biocrust. Disturbance (D) drives the

  15. Fractal scaling of particle size distribution and relationships with topsoil properties affected by biological soil crusts.

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    Guang-Lei Gao

    Full Text Available BACKGROUND: Biological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions. METHODOLOGY/PRINCIPAL FINDINGS: To distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of successional biological soil crusts (algae, lichens, and mosses crust, as well as the referenced sandland in the Mu Us Desert, Northern China. Relationships between fractal dimensions of soil particle size distribution and selected soil properties were discussed as well. The results indicated that biological soil crusts had significant positive effects on soil physical structure (P<0.05; and soil organic carbon and nutrients showed an upward trend across the successional stages of biological soil crusts. Fractal dimensions ranged from 2.1477 to 2.3032, and significantly linear correlated with selected soil properties (R(2 = 0.494∼0.955, P<0.01. CONCLUSIONS/SIGNIFICANCE: Biological soil crusts cause an important increase in soil fertility, and are beneficial to sand fixation, although the process is rather slow. Fractal dimension proves to be a sensitive and useful index for quantifying changes in soil properties that additionally implies desertification. This study will be essential to provide a firm basis for future policy-making on optimal solutions regarding desertification control and assessment, as well as degraded ecosystem restoration in arid and semiarid regions.

  16. Role of biological soil crusts in desert hydrology and geomorphology: Implications for military training operations

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    Steven D. Warren

    2014-01-01

    Biological soil crusts, composed of soil surfaces stabilized by a consortium of cyanobacteria, algae, fungi, lichens, and/or bryophytes, are common in most deserts and perform functions of primary productivity, nitrogen fixation, nutrient cycling, water redistribution, and soil stabilization. The crusts are highly susceptible to disturbance. The degree of perturbation...

  17. Influence of Disturbance on Soil Respiration in Biologically Crusted Soil during the Dry Season

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    Wei Feng

    2013-01-01

    Full Text Available Soil respiration (Rs is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss, as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60–70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.

  18. Linking soil biology and chemistry in biological soil crust using isolate exometabolomics.

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    Swenson, Tami L; Karaoz, Ulas; Swenson, Joel M; Bowen, Benjamin P; Northen, Trent R

    2018-01-02

    Metagenomic sequencing provides a window into microbial community structure and metabolic potential; however, linking these data to exogenous metabolites that microorganisms process and produce (the exometabolome) remains challenging. Previously, we observed strong exometabolite niche partitioning among bacterial isolates from biological soil crust (biocrust). Here we examine native biocrust to determine if these patterns are reproduced in the environment. Overall, most soil metabolites display the expected relationship (positive or negative correlation) with four dominant bacteria following a wetting event and across biocrust developmental stages. For metabolites that were previously found to be consumed by an isolate, 70% are negatively correlated with the abundance of the isolate's closest matching environmental relative in situ, whereas for released metabolites, 67% were positively correlated. Our results demonstrate that metabolite profiling, shotgun sequencing and exometabolomics may be successfully integrated to functionally link microbial community structure with environmental chemistry in biocrust.

  19. Advances, gaps, and future prospects in biological soil crust research

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    Weber, Bettina; Büdel, Burkhard; Belnap, Jayne

    2017-04-01

    Research progress has led to the understanding that biological soil crusts (biocrusts) are often complete miniature ecosystems comprising a variety of photosynthesizers (cyanobacteria, algae, lichens, bryophytes), decomposers like bacteria, fungi, and archaea, and heterotrophic organisms, like protozoa, nematodes, and microarthropods feeding on them. Biocrusts are one of the oldest terrestrial ecosystems, playing central roles in the structure and functioning of dryland ecosystems and presumably also influencing global biogeochemical cycles. On the other hand, biocrusts have been shown to be highly sensitive to global change, being easily destroyed by mechanical disturbance and severely threatened by minor changes in climate patterns. Despite the large increase in biocrust research, we still see major knowledge gaps which need to be tackled. Considering biodiversity studies, there are major regions of potential biocrust occurrence, where hardly any studies have been conducted. Molecular identification techniques are increasingly employed, but genetically characterized entities need to be linked with morphologically identified organisms to identify their ecological roles. Although there is a large body of research on the role of biocrusts in water and nutrient budgets, we are still far from closing the overall cycles. Results suggest that not all mechanisms have been identified, yet, leading to sometimes contradictory results between different studies. Knowledge on how to minimize impact to biocrusts during surface-disturbing activities has hardly been gained, and despite research efforts, instructions on effective biocrust restoration are still exemplary. In order to fill these research gaps, novel scientific approaches are needed. We expect that global research networks could be extremely helpful to answer scientific questions by tackling them within different regions, utilizing the same methodological techniques. Global networks could also be used for long

  20. Bryophyte-dominated biological soil crusts mitigate soil erosion in an early successional Chinese subtropical forest

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    S. Seitz

    2017-12-01

    Full Text Available This study investigated the development of biological soil crusts (biocrusts in an early successional subtropical forest plantation and their impact on soil erosion. Within a biodiversity and ecosystem functioning experiment in southeast China (biodiversity and ecosystem functioning (BEF China, the effect of these biocrusts on sediment delivery and runoff was assessed within micro-scale runoff plots under natural rainfall, and biocrust cover was surveyed over a 5-year period. Results showed that biocrusts occurred widely in the experimental forest ecosystem and developed from initial light cyanobacteria- and algae-dominated crusts to later-stage bryophyte-dominated crusts within only 3 years. Biocrust cover was still increasing after 6 years of tree growth. Within later-stage crusts, 25 bryophyte species were determined. Surrounding vegetation cover and terrain attributes significantly influenced the development of biocrusts. Besides high crown cover and leaf area index, the development of biocrusts was favoured by low slope gradients, slope orientations towards the incident sunlight and the altitude of the research plots. Measurements showed that bryophyte-dominated biocrusts strongly decreased soil erosion, being more effective than abiotic soil surface cover. Hence, their significant role in mitigating sediment delivery and runoff generation in mesic forest environments and their ability to quickly colonise soil surfaces after disturbance are of particular interest for soil erosion control in early-stage forest plantations.

  1. Bryophyte-dominated biological soil crusts mitigate soil erosion in an early successional Chinese subtropical forest

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    Seitz, Steffen; Nebel, Martin; Goebes, Philipp; Käppeler, Kathrin; Schmidt, Karsten; Shi, Xuezheng; Song, Zhengshan; Webber, Carla L.; Weber, Bettina; Scholten, Thomas

    2017-12-01

    This study investigated the development of biological soil crusts (biocrusts) in an early successional subtropical forest plantation and their impact on soil erosion. Within a biodiversity and ecosystem functioning experiment in southeast China (biodiversity and ecosystem functioning (BEF) China), the effect of these biocrusts on sediment delivery and runoff was assessed within micro-scale runoff plots under natural rainfall, and biocrust cover was surveyed over a 5-year period. Results showed that biocrusts occurred widely in the experimental forest ecosystem and developed from initial light cyanobacteria- and algae-dominated crusts to later-stage bryophyte-dominated crusts within only 3 years. Biocrust cover was still increasing after 6 years of tree growth. Within later-stage crusts, 25 bryophyte species were determined. Surrounding vegetation cover and terrain attributes significantly influenced the development of biocrusts. Besides high crown cover and leaf area index, the development of biocrusts was favoured by low slope gradients, slope orientations towards the incident sunlight and the altitude of the research plots. Measurements showed that bryophyte-dominated biocrusts strongly decreased soil erosion, being more effective than abiotic soil surface cover. Hence, their significant role in mitigating sediment delivery and runoff generation in mesic forest environments and their ability to quickly colonise soil surfaces after disturbance are of particular interest for soil erosion control in early-stage forest plantations.

  2. [Development and succession of artificial biological soil crusts and water holding characteristics of topsoil].

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    Wu, Li; Chen, Xiao-Guo; Zhang, Gao-Ke; Lan, Shu-Bin; Zhang, De-Lu; Hu, Chun-Xiang

    2014-03-01

    In order to understand the improving effects of cyanobacterial inoculation on water retention of topsoil in desert regions, this work focused on the development and succession of biological soil crusts and water holding characteristics of topsoil after cyanobacterial inoculation in Qubqi Desert. The results showed that after the artificial inoculation of desert cyanobacteria, algal crusts were quickly formed, and in some microenvironments direct succession of the algal crusts to moss crusts occurred after 2-3 years. With the development and succession of biological soil crusts, the topsoil biomass, polysaccharides content, crust thickness and porosity increased, while the soil bulk density decreased. At the same time, with crust development and succession, the topsoil texture became finer and the percents of fine soil particles including silt and clay contents increased, while the percents of coarse soil particles (sand content) decreased proportionately. In addition, it was found that with crust development and succession, the water holding capacity and water content of topsoil showed an increasing trend, namely: moss crust > algal crusts > shifting sand. The water content (or water holding capacity) in algal and moss crusts were 1.1-1.3 and 1.8-2.2 times of those in shifting sand, respectively. Correlation analysis showed that the water holding capacity and water content of topsoil were positively correlated with the crust biomass, polysaccharides content, thickness, bulk density, silt and clay content; while negatively correlated with the porosity and sand content. Furthermore, stepwise regression analysis showed that the main factor affecting water content was the clay content, while that affecting water holding capacity was the porosity.

  3. Growth and nutrient content of herbaceous seedlings associated with biological soil crusts

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    R. L. Pendleton; B. K. Pendleton; G. L. Howard; S. D. Warren

    2003-01-01

    Biological soil crusts of arid and semiarid lands contribute significantly to ecosystem stability by means of soil stabilization, nitrogen fixation, and improved growth and establishment of vascular plant species. In this study, we examined growth and nutrient content of Bromus tectorum, Elymus elymoides, Gaillardia pulchella, and Sphaeralcea munroana grown in soil...

  4. [Effect of trampling disturbance on soil infiltration of biological soil crusts].

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    Shi, Ya Fang; Zhao, Yun Ge; Li, Chen Hui; Wang, Shan Shan; Yang, Qiao Yun; Xie, Shen Qi

    2017-10-01

    The effect of trampling disturbance on soil infiltration of biological soil crusts was investigated by using simulated rainfall. The results showed that the trampling disturbance significantly increased soil surface roughness. The increasing extent depended on the disturbance intensity. Soil surface roughness values at 50% disturbance increased by 91% compared with the undisturbed treatment. The runoff was delayed by trampling disturbance. A linear increase in the time of runoff yield was observed along with the increasing disturbance intensity within 20%-50%. The time of runoff yield at 50% disturbance increased by 169.7% compared with the undisturbed treatment. Trampling disturbance increased soil infiltration and consequently decreased the runoff coefficient. The cumulative infiltration amount at 50% disturbance increased by 12.6% compared with the undisturbed treatment. Soil infiltration significant decreased when biocrusts were removed. The cumulative infiltration of the treatment of biocrusts removal decreased by 30.2% compared with the undisturbed treatment. Trampling disturbance did not significantly increase the soil loss when the distur bance intensity was lower than 50%, while the biocrusts removal resulted in 10 times higher in soil erosion modulus. The trampling disturbance of lower than 50% on biocrusts might improve soil infiltration and reduce the risk of runoff, thus might improve the soil moisture without obviously increa sing the soil loss.

  5. Patterns and controls on nitrogen cycling of biological soil crusts

    Science.gov (United States)

    Barger, Nichole N.; Zaady, Eli; Weber, Bettina; Garcia-Pichel, Ferran; Belnap, Jayne

    2016-01-01

    Biocrusts play a significant role in the nitrogen [N ] cycle within arid and semi-arid ecosystems, as they contribute major N inputs via biological fixation and dust capture, harbor internal N transformation processes, and direct N losses via N dissolved, gaseous and erosional loss processes (Fig. 1). Because soil N availability in arid and semi-arid ecosystems is generally low and may limit net primary production (NPP), especially during periods when adequate water is available, understanding the mechanisms and controls of N input and loss pathways in biocrusts is critically important to our broader understanding of N cycling in dryland environments. In particular, N cycling by biocrusts likely regulates short-term soil N availability to support vascular plant growth, as well as long-term N accumulation and maintenance of soil fertility. In this chapter, we review the influence of biocrust nutrient input, internal cycling, and loss pathways across a range of biomes. We examine linkages between N fixation capabilities of biocrust organisms and spatio-temporal patterns of soil N availability that may influence the longer-term productivity of dryland ecosystems. Lastly, biocrust influence on N loss pathways such as N gas loss, leakage of N compounds from biocrusts, and transfer in wind and water erosion are important to understand the maintenance of dryland soil fertility over longer time scales. Although great strides have been made in understanding the influence of biocrusts on ecosystem N cycling, there are important knowledge gaps in our understanding of the influence of biocrusts on ecosystem N cycling that should be the focus of future studies. Because work on the interaction of N cycling and biocrusts was reviewed in Belnap and Lange (2003), this chapter will focus primarily on research findings that have emerged over the last 15 years (2000-2015).

  6. Climatic sensitivity of dryland soil CO2 fluxes differs dramatically with biological soil crust successional state

    Science.gov (United States)

    Tucker, Colin; Ferrenberg, Scott; Reed, Sasha C.

    2018-01-01

    Arid and semiarid ecosystems make up approximately 41% of Earth’s terrestrial surface and are suggested to regulate the trend and interannual variability of the global terrestrial carbon (C) sink. Biological soil crusts (biocrusts) are common dryland soil surface communities of bryophytes, lichens, and/or cyanobacteria that bind the soil surface together and that may play an important role in regulating the climatic sensitivity of the dryland C cycle. Major uncertainties exist in our understanding of the interacting effects of changing temperature and moisture on CO2 uptake (photosynthesis) and loss (respiration) from biocrust and sub-crust soil, particularly as related to biocrust successional state. Here, we used a mesocosm approach to assess how biocrust successional states related to climate treatments. We subjected bare soil (Bare), early successional lightly pigmented cyanobacterial biocrust (Early), and late successional darkly pigmented moss-lichen biocrust (Late) to either ambient or + 5°C above ambient soil temperature for 84 days. Under ambient temperatures, Late biocrust mesocosms showed frequent net uptake of CO2, whereas Bare soil, Early biocrust, and warmed Late biocrust mesocosms mostly lost CO2 to the atmosphere. The inhibiting effect of warming on CO2 exchange was a result of accelerated drying of biocrust and soil. We used these data to parameterize, via Bayesian methods, a model of ecosystem CO2 fluxes, and evaluated the model with data from an autochamber CO2 system at our field site on the Colorado Plateau in SE Utah. In the context of the field experiment, the data underscore the negative effect of warming on fluxes both biocrust CO2 uptake and loss—which, because biocrusts are a dominant land cover type in this ecosystem, may extend to ecosystem-scale C cycling.

  7. The role of non-rainfall water on physiological activation in desert biological soil crusts

    Science.gov (United States)

    Zheng, Jiaoli; Peng, Chengrong; Li, Hua; Li, Shuangshuang; Huang, Shun; Hu, Yao; Zhang, Jinli; Li, Dunhai

    2018-01-01

    Non-rainfall water (NRW, e.g. fog and dew), in addition to rainfall and snowfall, are considered important water inputs to drylands. At the same time, biological soil crusts (BSCs) are important components of drylands. However, little information is available regarding the effect of NRW inputs on BSC activation. In this study, the effects of NRW on physiological activation in three BSC successional stages, including the cyanobacteria crust stage (Crust-C), moss colonization stage (Crust-CM), and moss crust stage (Crust-M), were studied in situ. Results suggest NRW inputs hydrated and activated physiological activity (Fv/Fm, carbon exchange, and nitrogen fixation) in BSCs but led to a negative carbon balance and low rates of nitrogen fixation in BSCs. One effective NRW event could hydrate BSCs for 7 h. Following simulated rainfall, the physiological activities recovered within 3 h, and net carbon gain occurred until 3 h after hydration, whereas NRW-induced physiological recovery processes were slower and exhibited lower activities, leading to a negative carbon balance. There were significant positive correlations between NRW amounts and the recovered values of Fv/Fm in all the three BSC stages (p < .001). The thresholds for Fv/Fm activation decreased with BSC succession, and the annual effective NRW events increased with BSC succession, with values of 29.8, 89.2, and 110.7 in Crust-C, Crust-CM and Crust-M, respectively. The results suggest that moss crust and moss-cyanobacteria crust use NRW to prolong metabolic activity and reduce drought stress more efficiently than cyanobacteria crusts. Therefore, these results suggest that BSCs utilize NRW to sustain life while growth and biomass accumulation require precipitation (rainfall) events over a certain threshold.

  8. Dew formation on the surface of biological soil crusts in central European sand ecosystems

    Directory of Open Access Journals (Sweden)

    T. Fischer

    2012-11-01

    Full Text Available Dew formation was investigated in three developmental stages of biological soil crusts (BSC, which were collected along a catena of an inland dune and in the initial substrate. The Penman equation, which was developed for saturated surfaces, was modified for unsaturated surfaces and used for prediction of dewfall rates. The levels of surface saturation required for this approach were predicted using the water retention functions and the thicknesses of the BSCs. During a first field campaign (2–3 August 2011, dewfall increased from 0.042 kg m−2 for the initial sandy substrate to 0.058, 0.143 and 0.178 kg m−2 for crusts 1 to 3, respectively. During a second field campaign (17–18 August 2011, where dew formation was recorded in 1.5 to 2.75-h intervals after installation at 21:30 CEST, dewfall increased from 0.011 kg m−2 for the initial sandy substrate to 0.013, 0.028 and 0.055 kg m−2 for crusts 1 to 3, respectively. Dewfall rates remained on low levels for the substrate and for crust 1, and decreased overnight for crusts 2 and 3 (with crust 3 > crust 2 > crust 1 throughout the campaign. Dew formation was well reflected by the model response. The suggested mechanism of dew formation involves a delay in water saturation in near-surface soil pores and extracellular polymeric substances (EPS where the crusts were thicker and where the water capacity was high, resulting in elevated vapor flux towards the surface. The results also indicate that the amount of dewfall was too low to saturate the BSCs and to observe water flow into deeper soil. Analysis of the soil water retention curves revealed that, despite the sandy mineral matrix, moist crusts clogged by swollen EPS pores exhibited a clay-like behavior. It is hypothesized that BSCs gain double benefit from suppressing their competitors by runoff generation and from improving their water supply by dew collection. Despite higher amounts of dew, the

  9. [Nitrogen fixation potential of biological soil crusts in southeast edge of Tengger Desert, Northwest China].

    Science.gov (United States)

    Zhang, Peng; Li, Xin-Rong; Zhang, Zhi-Shan; Pan, Yan-Xia; Liu, Yan-Mei; Su, Jie-Qiong

    2012-08-01

    Taking three typical types of biological soil crusts (BSCs), i.e., cyanobacterial-algal crust, lichen crust, and moss crust, in the southeast fringe of Tengger Desert as test objects, this paper studied their nitrogen fixation potential, seasonal fluctuation, and responses to the environmental factors from June 2010 to May 2011. During the whole study period, the nitrogenase activity (NA) of the cyanobacterial-algal, lichen, and moss crusts had significant difference, being 14-133, 20-101, and 4-28 micromol x m(-2) x h(-1), respectively, which indicated the critical role of the species composition of BSCs in nitrogen fixation. The NA of the three crust types had similar response characteristics to environmental factors. The NA had less correlation with the precipitation during the study period, but was positively correlated to the spring > summer > winter. The high air temperature in summer and the low air temperature (desert zone had nitrogen fixation capacity throughout the year, and the controlling effects of environmental factors on the nitrogen fixation were hierarchical. Water condition was the key factor affecting the nitrogen fixation rate and duration of the crusts, while under the conditions of sufficient water supply and carbon storage, heat condition dominated the crusts nitrogen fixation rate.

  10. [Effects of biological soil crust at different succession stages in hilly region of Loess Plateau on soil CO2 flux].

    Science.gov (United States)

    Wang, Ai-Guo; Zhao, Yun-Ge; Xu, Ming-Xiang; Yang, Li-Na; Ming, Jiao

    2013-03-01

    Biological soil crust (biocrust) is a compact complex layer of soil, which has photosynthetic activity and is one of the factors affecting the CO2flux of soil-atmosphere interface. In this paper, the soil CO, flux under the effects of biocrust at different succession stages on the re-vegetated grassland in the hilly region of Loess Plateau was measured by a modified LI-8100 automated CO, flux system. Under light condition, the soil CO2 flux under effects of cyanobacteria crust and moss crust was significantly decreased by 92% and 305%, respectively, as compared with the flux without the effects of the biocrusts. The decrement of the soil CO, flux by the biocrusts was related to the biocrusts components and their biomass. Under the effects of dark colored cyanobacteria crust and moss crust, the soil CO2 flux was decreased by 141% and 484%, respectively, as compared with that in bare land. The diurnal curve of soil CO2 flux under effects of biocrusts presented a trend of 'drop-rise-drop' , with the maximum carbon uptake under effects of cyanobacteria crust and moss crust being 0.13 and -1.02 micromol CO2.m-2.s-1 and occurred at about 8:00 and 9:00 am, respectively, while that in bare land was unimodal. In a day (24 h) , the total CO2 flux under effects of cyanobacteria crust was increased by 7.7% , while that under effects of moss crust was decreased by 29.6%, as compared with the total CO2 flux in bare land. This study suggested that in the hilly region of Loess Plateau, biocrust had significant effects on soil CO2 flux, which should be taken into consideration when assessing the carbon budget of the 'Grain for Green' eco-project.

  11. How development and disturbance of biological soil crust do affect runoff and erosion in drylands?

    Energy Technology Data Exchange (ETDEWEB)

    Chamizo, S.; Canton, Y.; Afana, A.; Lazaro, R.; Domingo, F.; Sole-Benet, A.

    2009-07-01

    Deserts and semiarid ecosystems (shrub lands and grasslands) are the largest terrestrial biome, covering more than 40% of the Earth's terrestrial surface and Biological Soil Crusts (BSCs) are the predominant surface type in most of those ecosystems covering up to 70% of its surface. BSCs have been demonstrated to be very vulnerable to disturbance due to human activities and their loss has been implicated as a factor leading to accelerate soil erosion and other forms of land degradation. Incorporation of the response of different type of soil crusts and the effects of the their disturbance is likely to improve the prediction of runoff and water erosion models in arid and semi-arid catchments. The aim of this work is to analyse the influence of crust disturbance on infiltration and erosion. Extreme rainfall simulations at micro plots scale were performed in two semiarid ecosystems with different lithology and conditions of occurrence of BSCs: El Cautivo and Amoladeras. (Author) 10 refs.

  12. How development and disturbance of biological soil crust do affect runoff and erosion in drylands?

    International Nuclear Information System (INIS)

    Chamizo, S.; Canton, Y.; Afana, A.; Lazaro, R.; Domingo, F.; Sole-Benet, A.

    2009-01-01

    Deserts and semiarid ecosystems (shrub lands and grasslands) are the largest terrestrial biome, covering more than 40% of the Earth's terrestrial surface and Biological Soil Crusts (BSCs) are the predominant surface type in most of those ecosystems covering up to 70% of its surface. BSCs have been demonstrated to be very vulnerable to disturbance due to human activities and their loss has been implicated as a factor leading to accelerate soil erosion and other forms of land degradation. Incorporation of the response of different type of soil crusts and the effects of the their disturbance is likely to improve the prediction of runoff and water erosion models in arid and semi-arid catchments. The aim of this work is to analyse the influence of crust disturbance on infiltration and erosion. Extreme rainfall simulations at micro plots scale were performed in two semiarid ecosystems with different lithology and conditions of occurrence of BSCs: El Cautivo and Amoladeras. (Author) 10 refs.

  13. Effects of Altered Temperature & Precipitation on Soil Bacterial & Microfaunal Communities as Mediated by Biological Soil Crusts

    Energy Technology Data Exchange (ETDEWEB)

    Neher, Deborah A. [University of Vermont

    2004-08-31

    With increased temperatures in our original pot study we observed a decline in lichen/moss crust cover and with that a decline in carbon and nitrogen fixation, and thus a probable decline of C and N input into crusts and soils. Soil bacteria and fauna were affected negatively by increased temperature in both light and dark crusts, and with movement from cool to hot and hot to hotter desert climates. Crust microbial biomass and relative abundance of diazotrophs was reduced greatly after one year, even in pots that were not moved from their original location, although no change in diazotroph community structure was observed. Populations of soil fauna moved from cool to hot deserts were affected more negatively than those moved from hot to hotter deserts.

  14. Ecological succession, hydrology and carbon acquisition of biological soil crusts measured at the micro-scale.

    Science.gov (United States)

    Tighe, Matthew; Haling, Rebecca E; Flavel, Richard J; Young, Iain M

    2012-01-01

    The hydrological characteristics of biological soil crusts (BSCs) are not well understood. In particular the relationship between runoff and BSC surfaces at relatively large (>1 m(2)) scales is ambiguous. Further, there is a dearth of information on small scale (mm to cm) hydrological characterization of crust types which severely limits any interpretation of trends at larger scales. Site differences and broad classifications of BSCs as one soil surface type rather than into functional form exacerbate the problem. This study examines, for the first time, some hydrological characteristics and related surface variables of a range of crust types at one site and at a small scale (sub mm to mm). X-ray tomography and fine scale hydrological measurements were made on intact BSCs, followed by C and C isotopic analyses. A 'hump' shaped relationship was found between the successional stage/sensitivity to physical disturbance classification of BSCs and their hydrophobicity, and a similar but 'inverse hump' relationship exists with hydraulic conductivity. Several bivariate relationships were found between hydrological variables. Hydraulic conductivity and hydrophobicity of BSCs were closely related but this association was confounded by crust type. The surface coverage of crust and the microporosity 0.5 mm below the crust surface were closely associated irrespective of crust type. The δ (13)C signatures of the BSCs were also related to hydraulic conductivity, suggesting that the hydrological characteristics of BSCs alter the chemical processes of their immediate surroundings via the physiological response (C acquisition) of the crust itself. These small scale results illustrate the wide range of hydrological properties associated with BSCs, and suggest associations between the ecological successional stage/functional form of BSCs and their ecohydrological role that needs further examination.

  15. Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts.

    Science.gov (United States)

    Darby, Brian J; Housman, David C; Zaki, Amr M; Shamout, Yassein; Adl, Sina M; Belnap, Jayne; Neher, Deborah A

    2006-01-01

    Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 degrees C. Cysts survived the upper end of daily temperatures (37-55 degrees C), and could be stimulated to excyst if temperatures were reduced to 15 degrees C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.

  16. The Role of Biological Soil Crusts in Nitrogen Cycling and Soil Deflation in West Greenland

    Science.gov (United States)

    Heindel, R. C.; Governali, F. C.; Spickard, A. M.; Virginia, R. A.

    2017-12-01

    Although shrub expansion has been observed across the Arctic in moist tundra habitat, shrubs may be prevented from expanding in arid Arctic regions due to low soil moisture or soil erosion. This may be the case in Kangerlussuaq, West Greenland, where katabatic winds off the Greenland Ice Sheet have eroded distinct patches of mixed shrub tundra, resulting in nearly barren low productivity areas dominated by biological soil crusts (biocrusts) and graminoids. The future trajectory of these bare patches - persisting in a low biomass state or returning to a shrub-dominated state - depends on the role of the biocrust as either a long-term landscape cover limiting revegetation or as a successional facilitator. Prior to this study, little was known about the physical and ecological development of West Greenland biocrusts and how they may influence future vegetation dynamics. We found that biocrusts took 230 ± 48 years to fully develop, and that later stages of biocrust development were related to increased thickness and penetration resistance and decreased soil moisture, factors limiting shrub seedling establishment. The nitrogen (N) fixing lichen Stereocaulon sp. was found throughout the study region at all stages of biocrust development. Natural 15N abundance suggests that Stereocaulon sp. obtains about half of its N from biological fixation, and that some biologically-fixed N is incorporated into the underlying soils over time. Although soil N and C concentrations increased slightly with biocrust development, their levels under the most developed biocrusts remained low compared to the surrounding shrub and graminoid tundra. Our results suggest that deflation patches, triggered by long-term variations in climate, may remain in a low-productivity ecosystem state for hundreds to thousands of years, if precipitation and temperature regimes do not dramatically alter the vegetation potential of the region. However, if future climate change in the Arctic favors greater

  17. Carbon exchange in biological soil crust communities under differential temperatures and soil water contents: implications for global change

    Science.gov (United States)

    Grote, Edmund E.; Belnap, Jayne; Housman, David C.; Sparks, Jed P.

    2010-01-01

    Biological soil crusts (biocrusts) are an integral part of the soil system in arid regions worldwide, stabilizing soil surfaces, aiding vascular plant establishment, and are significant sources of ecosystem nitrogen and carbon. Hydration and temperature primarily control ecosystem CO2 flux in these systems. Using constructed mesocosms for incubations under controlled laboratory conditions, we examined the effect of temperature (5-35 1C) and water content (WC, 20-100%) on CO2 exchange in light cyanobacterially dominated) and dark cyanobacteria/lichen and moss dominated) biocrusts of the cool Colorado Plateau Desert in Utah and the hot Chihuahuan Desert in New Mexico. In light crusts from both Utah and New Mexico, net photosynthesis was highest at temperatures 430 1C. Net photosynthesis in light crusts from Utah was relatively insensitive to changes in soil moisture. In contrast, light crusts from New Mexico tended to exhibit higher rates of net photosynthesis at higher soil moisture. Dark crusts originating from both sites exhibited the greatest net photosynthesis at intermediate soil water content (40-60%). Declines in net photosynthesis were observed in dark crusts with crusts from Utah showing declines at temperatures 425 1C and those originating from New Mexico showing declines at temperatures 435 1C. Maximum net photosynthesis in all crust types from all locations were strongly influenced by offsets in the optimal temperature and water content for gross photosynthesis compared with dark respiration. Gross photosynthesis tended to be maximized at some intermediate value of temperature and water content and dark respiration tended to increase linearly. The results of this study suggest biocrusts are capable of CO2 exchange under a wide range of conditions. However, significant changes in the magnitude of this exchange should be expected for the temperature and precipitation changes suggested by current climate models.

  18. Emission of nitrous acid from soil and biological soil crusts as a major source of atmospheric HONO on Cyprus

    Science.gov (United States)

    Meusel, Hannah; Tamm, Alexandra; Wu, Dianming; Kuhn, Uwe; Leifke, Anna-Lena; Weber, Bettina; Su, Hang; Lelieveld, Jos; Hoffmann, Thorsten; Pöschl, Ulrich; Cheng, Yafang

    2017-04-01

    Elucidation of the sources and atmospheric chemistry of nitrous acid (HONO) is highly relevant, as HONO is an important precursor of OH radicals. Up to 30% of the OH budget are formed by photolysis of HONO, whereas major fractions of HONO measured in the field derive from yet unidentified sources. Heterogeneous conversion of nitrogen dioxide (NO2) to HONO on a variety of surfaces (soot, humic acid aerosol) is assumed to be a major HONO source (Stemmler et al., 2007, Ammann et al., 1998). In rural regions, however, NO2 concentrations were found to be too low to explain observed HONO concentrations, as e.g., in the case of a recent field study on the Mediterranean island of Cyprus (Meusel et al., 2016). In this study a good correlation between missing sources of HONO and nitrogen oxide (NO) was found indicating a common origin of both reactive nitrogen compounds. Simultaneous emission of HONO and NO from soil was reported earlier (Oswald et al., 2013), and enhanced emission rates were found when soil was covered by biological soil crusts in arid and semi-arid ecosystems (Weber et al., 2015). In the present study we measured HONO and NO emissions of 43 soil and soil crust samples from Cyprus during full wetting and drying cycles under controlled laboratory conditions by means of a dynamic chamber system. The observed range of HONO and NO emissions was in agreement with earlier studies, but unlike the study of Weber et al. (2015), we found highest emission from bare soil, followed by soil covered by light and dark cyanobacteria-dominated biological soil crusts. Emission rates correlated well with the nitrite and nitrate contents of soil and biological soil crust samples, and higher nutrient contents of bare soil samples, as compared to the previous biological soil crust study, explain the higher bare soil emissions. Integrating the emission rates of bare soil and the different types of biological soil crusts, based on their local relative abundance, the calculated

  19. Three-dimensional structure and cyanobacterial activity within a desert biological soil crust.

    Science.gov (United States)

    Raanan, Hagai; Felde, Vincent J M N L; Peth, Stephan; Drahorad, Sylvie; Ionescu, Danny; Eshkol, Gil; Treves, Haim; Felix-Henningsen, Peter; Berkowicz, Simon M; Keren, Nir; Horn, Rainer; Hagemann, Martin; Kaplan, Aaron

    2016-02-01

    Desert biological soil crusts (BSCs) are formed by adhesion of soil particles to polysaccharides excreted by filamentous cyanobacteria, the pioneers and main producers in this habitat. Biological soil crust destruction is a central factor leading to land degradation and desertification. We study the effect of BSC structure on cyanobacterial activity. Micro-scale structural analysis using X-ray microtomography revealed a vesiculated layer 1.5-2.5 mm beneath the surface in close proximity to the cyanobacterial location. Light profiles showed attenuation with depth of 1%-5% of surface light within 1 mm but also revealed the presence of 'light pockets', coinciding with the vesiculated layer, where the irradiance was 10-fold higher than adjacent crust parts at the same depth. Maximal photosynthetic activity, examined by O2 concentration profiles, was observed 1 mm beneath the surface and another peak in association with the 'light pockets'. Thus, photosynthetic activity may not be visible to currently used remote sensing techniques, suggesting that BSCs' contribution to terrestrial productivity is underestimated. Exposure to irradiance higher than 10% full sunlight diminished chlorophyll fluorescence, whereas O2 evolution and CO2 uptake rose, indicating that fluorescence did not reflect cyanobacterial photosynthetic activity. Our data also indicate that although resistant to high illumination, the BSC-inhabiting cyanobacteria function as 'low-light adapted' organisms. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  20. Biological soil crusts as an organizing principle in drylands: Chapter 1

    Science.gov (United States)

    Belnap, Jayne; Weber, Bettina; Büdel, Burkhard; Weber, Bettina; Buedel, Burkhard; Belnap, Jayne

    2016-01-01

    Biological soil crusts (biocrusts) have been present on Earth’s terrestrial surfaces for billions of years. They are a critical part of ecosystem processes in dryland regions, as they cover most of the soil surface and thus mediate almost all inputs and outputs from soils in these areas. There are many intriguing, but understudied, roles these communities may play in drylands. These include their function in nutrient capture and transformation, influence on the movement and distribution of nutrients and water within dryland soils, ability to structure vascular plant communities, role in creating biodiversity hotspots, and the possibility that they can be used as indicators of soil health. There are still many fascinating aspects of these communities that need study, and we hope that this chapter will facilitate such efforts.

  1. Rapidly restoring biological soil crusts and ecosystem functions in a severely disturbed desert ecosystem.

    Science.gov (United States)

    Chiquoine, Lindsay P; Abella, Scott R; Bowker, Matthew A

    2016-06-01

    Restoring biological soil crusts (biocrusts) in degraded drylands can contribute to recovery of ecosystem functions that have global implications, including erosion resistance and nutrient cycling. To examine techniques for restoring biocrusts, we conducted a replicated, factorial experiment on recently abandoned road surfaces by applying biocrust inoculation (salvaged and stored dry for two years), salvaged topsoil, an abiotic soil amendment (wood shavings), and planting of a dominant perennial shrub (Ambrosia dumosa). Eighteen months after treatments, we measured biocrust abundance and species composition, soil chlorophyll a content and fertility, and soil resistance to erosion. Biocrust addition significantly accelerated biocrust recovery on disturbed soils, including increasing lichen and moss cover and cyanobacteria colonization. Compared to undisturbed controls, inoculated plots had similar lichen and moss composition, recovered 43% of total cyanobacteria density, had similar soil chlorophyll content, and exhibited recovery of soil fertility and soil stability. Inoculation was the only treatment that generated lichen and moss cover. Topsoil application resulted in partial recovery of the cyanobacteria community and soil properties. Compared to untreated disturbed plots, topsoil application without inoculum increased cyanobacteria density by 186% and moderately improved soil chlorophyll and ammonium content and soil stability. Topsoil application produced 22% and 51% of the cyanobacteria density g⁻¹ soil compared to undisturbed and inoculated plots, respectively. Plots not treated with either topsoil or inoculum had significantly lower cyanobacteria density, soil chlorophyll and ammonium concentrations, and significantly higher soil nitrate concentration. Wood shavings and Ambrosia had no influence on biocrust lichen and moss species recovery but did affect cyanobacteria composition and soil fertility. Inoculation of severely disturbed soil with native

  2. Measurement of dinitrogen fixation by Biological soil crust (BSC) from the Sahelian zone: an isotopic method.

    Science.gov (United States)

    Ehrhardt, F.; Alavoine, G.; Bertrand, I.

    2012-04-01

    Amongst the described ecological roles of Biological Soil Crust, N fixation is of importance for soil fertility, especially in arid and semi-arid ecosystems with low inputs. In BSC, the quantification of N fixation fluxes using an indirect method is widespread, usually with the Acetylene Reduction Assay (ARA) which consists in measuring the nitrogenase activity through the process of acetylene reduction into ethylene. A converting factor, still discussed in the literature and greatly depending of the constitutive organisms of the BSC, is the tool used to convert the amount of reduced ethylene into quantitative fixed Nitrogen. The aim of this poster is to describe an isotopic direct method to quantify the atmospheric dinitrogen fixation fluxes in BSC, while minimizing the variability due to manipulations. Nine different BSC from the Sahelian zone were selected and placed in an incubation room at 28° C in dark and light conditions during three days, while moisture equivalent to pF=2 was regularly adjusted using the gravimetric method with needles and deionized water, in order to activate and reach a dynamic stability of their metabolisms. Subsequently, each crust was placed into a gas-tight glass vial for incubation with a reconstituted 15N2 enriched atmosphere (31.61 % atom 15N, while the proportion of each main gas present in the air was conserved, i.e. 78% N2, 21% O2 and 0.04% CO2). Principal difficulties are to guarantee the airtighness of the system, to avoid crust desiccation and to keep the crust metabolically active under stable conditions for six hours. Several tests were performed to determine the optimum time for 15N2 incubation. Three replicated control samples per crust were also stabilized for three days and then dried at 105° C, without any incubation with 15N2 enriched atmosphere. Total N and 15N were then measured in the grounded (80μm) and dried (105° C) crust, using a Flash EA elemental analyzer (Eurovector, Milan, Italy) coupled to a Delta

  3. Investigating the Effect of Biological Crusts on Some Biological Properties of Soil (Case Study: Qare Qir Rangelands of Golestan Province

    Directory of Open Access Journals (Sweden)

    J. Kakeh

    2016-09-01

    Full Text Available Introduction: Physical and biological soil crusts are the principal types of soil crusts. Physical and biological soil crusts are distributed in arid, semi-arid and sub-humid regions which constitute over 40% of the earth terrestrial surface. Biological soil crusts (BSCs result from an intimate association between soil particles and cyanobacteria, algae, fungi, lichens and mosses in different proportions which live on the surface, or in the immediately uppermost millimeters of soil. Some of the functions that BSCs influences include: water absorption and retention, nutrient retention, Carbon and nitrogen fixation, biological activate and hydrologic Status. BSCs are important from the ecological view point and their effects on the environment, especially in rangeland, and desert ecosystems and this caused which researchers have a special attention to this component of the ecosystems more than before. Materials and Methods: This study carried out in the Qara Qir rangelands of Golestan province, northeast of Iran (37º15′ - 37º23′ N &54º33′ -54º39′ E, to investigate the effects of BSCs on some of soil biological properties. Four sites including with and without BSCs cover were selected. Soil biological properties such as microbial populations, soil respiration, microbial biomass carbon and nitrogen, as well as, other effective properties such asorganic carbon percent, total nitrogen, electrical conductivity, and available water content were measured in depths of 0-5 and 5-15 cm of soil with four replications. The gathered data were analyzed by nested plot, and the mean values were compared by Duncan test. Results and Discussion: The results showed that organic carbon and water content were higher at the surface under BSCs, followed by 5-15 cm soils under BSCs. Both soil depths of uncrusted soils showed substantially lower organic carbon and water content than the BSC-covered soils. Total nitrogen was far higher in BSC-encrusted surface

  4. High rates of denitrification and nitrous oxide emission in arid biological soil crusts from the Sultanate of Oman

    DEFF Research Database (Denmark)

    Abed, Raeid M M; Lam, Phyllis; De Beer, Dirk

    2013-01-01

    Using a combination of process rate determination, microsensor profiling and molecular techniques, we demonstrated that denitrification, and not anaerobic ammonium oxidation (anammox), is the major nitrogen loss process in biological soil crusts from Oman. Potential denitrification rates were 584...... that nitrogen loss via denitrification is a dominant process in crusts from Oman, which leads to N 2 O gas emission and potentially reduces desert soil fertility....

  5. Frequent fire promotes diversity and cover of biological soil crusts in a derived temperate grassland.

    Science.gov (United States)

    O'Bryan, Katharine E; Prober, Suzanne Mary; Lunt, Ian D; Eldridge, David J

    2009-04-01

    The intermediate disturbance hypothesis (IDH) predicts that species diversity is maximized at moderate disturbance levels. This model is often applied to grassy ecosystems, where disturbance can be important for maintaining vascular plant composition and diversity. However, effects of disturbance type and frequency on cover and diversity of non-vascular plants comprising biological soil crusts are poorly known, despite their potentially important role in ecosystem function. We established replicated disturbance regimes of different type (fire vs. mowing) and frequency (2, 4, 8 yearly and unburnt) in a high-quality, representative Themeda australis-Poa sieberiana derived grassland in south-eastern Australia. Effects on soil crust bryophytes and lichens (hereafter cryptogams) were measured after 12 years. Consistent with expectations under IDH, cryptogam richness and abundance declined under no disturbance, likely due to competitive exclusion by vascular plants as well as high soil turnover by soil invertebrates beneath thick grass. Disturbance type was also significant, with burning enhancing richness and abundance more than mowing. Contrary to expectations, however, cryptogam richness increased most dramatically under our most frequent and recent (2 year) burning regime, even when changes in abundance were accounted for by rarefaction analysis. Thus, from the perspective of cryptogams, 2-year burning was not an adequately severe disturbance regime to reduce diversity, highlighting the difficulty associated with expression of disturbance gradients in the application of IDH. Indeed, significant correlations with grassland structure suggest that cryptogam abundance and diversity in this relatively mesic (600 mm annual rainfall) grassland is maximised by frequent fires that reduce vegetation and litter cover, providing light, open areas and stable soil surfaces for colonisation. This contrasts with detrimental effects of 2-year burning on native perennial grasses

  6. Dynamic cyanobacterial response to hydration and dehydration in a desert biological soil crust.

    Science.gov (United States)

    Rajeev, Lara; da Rocha, Ulisses Nunes; Klitgord, Niels; Luning, Eric G; Fortney, Julian; Axen, Seth D; Shih, Patrick M; Bouskill, Nicholas J; Bowen, Benjamin P; Kerfeld, Cheryl A; Garcia-Pichel, Ferran; Brodie, Eoin L; Northen, Trent R; Mukhopadhyay, Aindrila

    2013-11-01

    Biological soil crusts (BSCs) cover extensive portions of the earth's deserts. In order to survive desiccation cycles and utilize short periods of activity during infrequent precipitation, crust microorganisms must rely on the unique capabilities of vegetative cells to enter a dormant state and be poised for rapid resuscitation upon wetting. To elucidate the key events involved in the exit from dormancy, we performed a wetting experiment of a BSC and followed the response of the dominant cyanobacterium, Microcoleus vaginatus, in situ using a whole-genome transcriptional time course that included two diel cycles. Immediate, but transient, induction of DNA repair and regulatory genes signaled the hydration event. Recovery of photosynthesis occurred within 1 h, accompanied by upregulation of anabolic pathways. Onset of desiccation was characterized by the induction of genes for oxidative and photo-oxidative stress responses, osmotic stress response and the synthesis of C and N storage polymers. Early expression of genes for the production of exopolysaccharides, additional storage molecules and genes for membrane unsaturation occurred before drying and hints at preparedness for desiccation. We also observed signatures of preparation for future precipitation, notably the expression of genes for anaplerotic reactions in drying crusts, and the stable maintenance of mRNA through dormancy. These data shed light on possible synchronization between this cyanobacterium and its environment, and provides key mechanistic insights into its metabolism in situ that may be used to predict its response to climate, and or, land-use driven perturbations.

  7. How biological soil crusts became recognized as a functional unit: a selective history

    Science.gov (United States)

    Lange, Otto L.; Belnap, Jayne

    2016-01-01

    It is surprising that despite the world-wide distribution and general importance of biological soil crusts (biocrusts), scientific recognition and functional analysis of these communities is a relatively young field of science. In this chapter, we sketch the historical lines that led to the recognition of biocrusts as a community with important ecosystem functions. The idea of biocrusts as a functional ecological community has come from two main scientific branches: botany and soil science. For centuries, botanists have long recognized that multiple organisms colonize the soil surface in the open and often dry areas occurring between vascular plants. Much later, after the initial taxonomic and phyto-sociological descriptions were made, soil scientists and agronomists observed that these surface organisms interacted with soils in ways that changed the soil structure. In the 1970’s, research on these communities as ecological units that played an important functional role in drylands began in earnest, and these studies have continued to this day. Here, we trace the history of these studies from the distant past until 1990, when biocrusts became well-known to scientists and the public.

  8. Biological soil crust and disturbance controls on surface hydrology in a semi-arid ecosystem

    Science.gov (United States)

    Faist, Akasha M; Herrick, Jeffrey E.; Belnap, Jayne; Van Zee, Justin W; Barger, Nichole N

    2017-01-01

    Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems, and these processes may then be dramatically altered with soil surface disturbance. In this study, we examined biocrust hydrologic responses to disturbance at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance (trampling, scalping and trampling+scalping) of the early successional light cyanobacterial biocrusts generally reduced runoff. In contrast, trampling well-developed dark-cyano-lichen biocrusts increased runoff and sediment loss relative to intact controls. Scalping did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff, low sediment loss, and highest aggregate stability whereas the less-developed light biocrusts were highest in runoff and sediment loss when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

  9. The effects of extreme rainfall events on carbon release from Biological Soil Crusts covered soil in fixed sand dunes in the Tengger Desert, northern China

    Science.gov (United States)

    Zhao, Yang; Li, Xinrong; Pan, Yanxia; Hui, Rong

    2016-04-01

    How soil cover types and extreme rainfall event influence carbon (C) release in temperate desert ecosystems has largely been unexplored. We assessed the effects of extreme rainfall (quantity and intensity) events on the carbon release from soils covered by different types of biological soil crusts (BSCs) in fixed sand dunes in the Tengger Desert, Shapotou regionof northern China. We removed intact crusts down to 10 cm and measured them in PVC mesocosms. A Li-6400-09 Soil Chamber was used to measure the respiration rates of the BSCs immediately after the rainfall stopped, and continued until the respiration rates of the BSCs returned to the pre-rainfall basal rate. Our results showed that almost immediately after extreme rainfall events the respiration rates of algae crust and mixed crust were significantly inhibited, but moss crust was not significantly affected. The respiration rates of algae crust, mixed crust, and moss crust in extreme rainfall quantity and intensity events were, respectively, 0.12 and 0.41 μmolCO2/(m2•s), 0.10 and 0.45 μmolCO2/(m2•s), 0.83 and 1.69 μmolCO2/(m2•s). Our study indicated that moss crust in the advanced succession stage can well adapt to extreme rainfall events in the short term. Keywords: carbon release; extreme rainfall events; biological soil crust

  10. Ecophysiological characterization of early successional biological soil crusts in heavily human-impacted areas

    Science.gov (United States)

    Szyja, Michelle; Büdel, Burkhard; Colesie, Claudia

    2018-04-01

    Ecophysiological characterizations of photoautotrophic communities are not only necessary to identify the response of carbon fixation related to different climatic factors, but also to evaluate risks connected to changing environments. In biological soil crusts (BSCs), the description of ecophysiological features is difficult, due to the high variability in taxonomic composition and variable methodologies applied. Especially for BSCs in early successional stages, the available datasets are rare or focused on individual constituents, although these crusts may represent the only photoautotrophic component in many heavily disturbed ruderal areas, such as parking lots or building areas with increasing surface area worldwide. We analyzed the response of photosynthesis and respiration to changing BSC water contents (WCs), temperature and light in two early successional BSCs. We investigated whether the response of these parameters was different between intact BSC and the isolated dominating components. BSCs dominated by the cyanobacterium Nostoc commune and dominated by the green alga Zygogonium ericetorum were examined. A major divergence between the two BSCs was their absolute carbon fixation rate on a chlorophyll basis, which was significantly higher for the cyanobacterial crust. Nevertheless, independent of species composition, both crust types and their isolated organisms had convergent features such as high light acclimatization and a minor and very late-occurring depression in carbon uptake at water suprasaturation. This particular setup of ecophysiological features may enable these communities to cope with a high variety of climatic stresses and may therefore be a reason for their success in heavily disturbed areas with ongoing human impact. However, the shape of the response was different for intact BSC compared to separated organisms, especially in absolute net photosynthesis (NP) rates. This emphasizes the importance of measuring intact BSCs under natural

  11. Ecohydrological role of biological soil crusts across a gradient in levels of development

    Science.gov (United States)

    Whitney, Kristen M.; Vivoni, Enrique R.; Duniway, Michael C.; Bradford, John B.; Reed, Sasha C.; Belnap, Jayne

    2017-01-01

    Though biological soil crusts (biocrusts) form abundant covers in arid and semiarid regions, their competing effects on soil hydrologic conditions are rarely accounted for in models. This study presents the modification of a soil water balance model to account for the presence of biocrusts at different levels of development (LOD) and their impact on one-dimensional hydrologic processes during warm and cold seasons. The model is developed, tested, and applied to study the hydrologic controls of biocrusts in context of a long-term manipulative experiment equipped with meteorological and soil moisture measurements in a Colorado Plateau ecosystem near Moab, Utah. The climate manipulation treatments resulted in distinct biocrust communities, and model performance with respect to soil moisture was assessed in experimental plots with varying LOD as quantified through a field-based roughness index (RI). Model calibration and testing yielded excellent comparisons to observations and smooth variations of biocrust parameters with RI approximated through simple regressions. The model was then used to quantify how LOD affects soil infiltration, evapotranspiration, and runoff under calibrated conditions and in simulation experiments with gradual modifications in biocrust porosity and hydraulic conductivity. Simulation results show that highly developed biocrusts modulate soil moisture nonlinearly with LOD by altering soil infiltration and buffering against evapotranspiration losses, with small impacts on runoff. The nonlinear and threshold variations of the soil water balance in the presence of biocrusts of varying LOD helps explain conflicting outcomes of various field studies and sheds light on the ecohydrological role of biocrusts in arid and semiarid ecosystems.

  12. Correlates of biological soil crust abundance across a continuum of spatial scales: Support for a hierarchical conceptual model

    Science.gov (United States)

    Bowker, M.A.; Belnap, J.; Davidson, D.W.; Goldstein, H.

    2006-01-01

    1. Desertification negatively impacts a large proportion of the global human population and > 30% of the terrestrial land surface. Better methods are needed to detect areas that are at risk of desertification and to ameliorate desertified areas. Biological soil crusts are an important soil lichen-moss-microbial community that can be used toward these goals, as (i) bioindicators of desertification damage and (ii) promoters of soil stability and fertility. 2. We identified environmental factors that correlate with soil crust occurrence on the landscape and might be manipulated to assist recovery of soil crusts in degraded areas. We conducted three studies on the Colorado Plateau, USA, to investigate the hypotheses that soil fertility [particularly phosphorus (P), manganese (Mn) and zinc (Zn)] and/or moisture limit soil crust lichens and mosses at four spatial scales. 3. In support of the soil fertility hypothesis, we found that lichen-moss crusts were positively correlated with several nutrients [Mn, Zn, potassium (K) and magnesium (Mg) were most consistent] at three of four spatial scales ranging from 3.5 cm2 in area to c. 800 km2. In contrast, P was negatively correlated with lichen-moss crusts at three scales. 4. Community composition varied with micro-aspect on ridges in the soil crust. Three micro-aspects [north-north-west (NNW), east-north-east (ENE) and TOP] supported greater lichen and moss cover than the warmer, windward and more xeric micro-aspects [west-south-west (WSW) and south-south-east (SSE)]. This pattern was poorly related to soil fertility; rather, it was consistent with the moisture limitation hypothesis. 5. Synthesis and application. Use of crusts as desertification bioindicators requires knowledge of a site's potential for crust cover in the absence of desertification. We present a multi-scale model of crust potential as a function of site properties. Future quantitative studies can use this model to guide sampling efforts. Also, our results

  13. Biological soil crusts in deserts: A short review of their role in soil fertility, stabilization, and water relations

    Science.gov (United States)

    Belnap, Jayne

    2003-01-01

    Cyanobacteria and cyanolichens dominate most desert soil surfaces as the major component of biological soil crusts (BSC). BSCs contribute to soil fertility in many ways. BSC can increase weathering of parent materials by up to 100 times. Soil surface biota are often sticky, and help retain dust falling on the soil surface; this dust provides many plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. BSCs also provide roughened soil surfaces that slow water runoff and aid in retaining seeds and organic matter. They provide inputs of newly-fixed carbon and nitrogen to soils. They are essential in stabilizing soil surfaces by linking soil particles together with filamentous sheaths, enabling soils to resist both water and wind erosion. These same sheaths are important in keeping soil nutrients from becoming bound into plant-unavailable forms. Experimental disturbances applied in US deserts show soil surface impacts decrease N and C inputs from soil biota by up to 100%. The ability to hold aeolian deposits in place is compromised, and underlying soils are exposed to erosion. While most undisturbed sites show little sediment production, disturbance by vehicles or livestock produces up to 36 times more sediment production, with soil movement initiated at wind velocities well below commonly-occurring wind speeds. Winds across disturbed areas can quickly remove this material from the soil surface, thereby potentially removing much of current and future soil fertility. Thus, reduction in the cover of cyanophytes in desert soils can both reduce fertility inputs and accelerate fertility losses.

  14. Cyanobacterial Diversity in Biological Soil Crusts along a Precipitation Gradient, Northwest Negev Desert, Israel.

    Science.gov (United States)

    Hagemann, Martin; Henneberg, Manja; Felde, Vincent J M N L; Drahorad, Sylvie L; Berkowicz, Simon M; Felix-Henningsen, Peter; Kaplan, Aaron

    2015-07-01

    Cyanobacteria occur worldwide but play an important role in the formation and primary activity of biological soil crusts (BSCs) in arid and semi-arid ecosystems. The cyanobacterial diversity in BSCs of the northwest Negev desert of Israel was surveyed at three fixed sampling stations situated along a precipitation gradient in the years 2010 to 2012. The three stations also are characterized by marked differences in soil features such as soil carbon, nitrogen, or electrical conductivity. The cyanobacterial biodiversity was analyzed by sequencing inserts of clone libraries harboring partial 16S rRNA gene sequences obtained with cyanobacteria-specific primers. Filamentous, non-diazotrophic strains (subsection III), particularly Microcoleus-like, dominated the cyanobacterial community (30% proportion) in all years. Specific cyanobacterial groups showed increased (e.g., Chroococcidiopsis, Leptolyngbya, and Nostoc strains) or decreased (e.g., unicellular strains belonging to the subsection I and Scytonema strains) abundances with declining water availability at the most arid, southern station, whereas many cyanobacterial strains were frequently found in the soils of all three stations. The cyanobacterial diversity at the three sampling stations appears dependent on the available precipitation, whereas the differences in soil chemistry were of lower importance.

  15. Biological soil crusts emit large amounts of NO and HONO affecting the nitrogen cycle in drylands

    Science.gov (United States)

    Tamm, Alexandra; Wu, Dianming; Ruckteschler, Nina; Rodríguez-Caballero, Emilio; Steinkamp, Jörg; Meusel, Hannah; Elbert, Wolfgang; Behrendt, Thomas; Sörgel, Matthias; Cheng, Yafang; Crutzen, Paul J.; Su, Hang; Pöschl, Ulrich; Weber, Bettina

    2016-04-01

    Dryland systems currently cover ˜40% of the world's land surface and are still expanding as a consequence of human impact and global change. In contrast to that, information on their role in global biochemical processes is limited, probably induced by the presumption that their sparse vegetation cover plays a negligible role in global balances. However, spaces between the sparse shrubs are not bare, but soils are mostly covered by biological soil crusts (biocrusts). These biocrust communities belong to the oldest life forms, resulting from an assembly between soil particles and cyanobacteria, lichens, bryophytes, and algae plus heterotrophic organisms in varying proportions. Depending on the dominating organism group, cyanobacteria-, lichen-, and bryophyte-dominated biocrusts are distinguished. Besides their ability to restrict soil erosion they fix atmospheric carbon and nitrogen, and by doing this they serve as a nutrient source in strongly depleted dryland ecosystems. In this study we show that a fraction of the nitrogen fixed by biocrusts is metabolized and subsequently returned to the atmosphere in the form of nitric oxide (NO) and nitrous acid (HONO). These gases affect the radical formation and oxidizing capacity within the troposphere, thus being of particular interest to atmospheric chemistry. Laboratory measurements using dynamic chamber systems showed that dark cyanobacteria-dominated crusts emitted the largest amounts of NO and HONO, being ˜20 times higher than trace gas fluxes of nearby bare soil. We showed that these nitrogen emissions have a biogenic origin, as emissions of formerly strongly emitting samples almost completely ceased after sterilization. By combining laboratory, field, and satellite measurement data we made a best estimate of global annual emissions amounting to ˜1.1 Tg of NO-N and ˜0.6 Tg of HONO-N from biocrusts. This sum of 1.7 Tg of reactive nitrogen emissions equals ˜20% of the soil release under natural vegetation according

  16. Identification of factors influencing the restoration of cyanobacteria-dominated biological soil crusts.

    Directory of Open Access Journals (Sweden)

    Chongfeng Bu

    Full Text Available Biological soil crusts (BSCs cover >35% of the Earth's land area and contribute to important ecological functions in arid and semiarid ecosystems, including erosion reduction, hydrological cycling, and nutrient cycling. Artificial rapid cultivation of BSCs can provide a novel alternative to traditional biological methods for controlling soil and water loss such as the planting of trees, shrubs, and grasses. At present, little is known regarding the cultivation of BSCs in the field due to lack of knowledge regarding the influencing factors that control BSCs growth. Thus, we determined the effects of various environmental factors (shade; watering; N, P, K, and Ca concentrations on the growth of cyanobacteria-dominated BSCs from the Sonoran Desert in the southwestern United States. The soil surface changes and chlorophyll a concentrations were used as proxies of BSC growth and development. After 4 months, five factors were found to impact BSC growth with the following order of importance: NH4NO3 ≈ watering frequency>shading>CaCO3 ≈ KH2PO4. The soil water content was the primary positive factor affecting BSC growth, and BSCs that were watered every 5 days harbored greater biomass than those watered every 10 days. Groups that received NH4NO3 consistently exhibited poor growth, suggesting that fixed N amendment may suppress BSC growth. The effect of shading on the BSC biomass was inconsistent and depended on many factors including the soil water content and availability of nutrients. KH2PO4 and CaCO3 had nonsignificant effects on BSC growth. Collectively, our results indicate that the rapid restoration of BSCs can be controlled and realized by artificial "broadcasting" cultivation through the optimization of environmental factors.

  17. Isolation of a significant fraction of non-phototroph diversity from a desert Biological Soil Crust

    Directory of Open Access Journals (Sweden)

    Ulisses eNunes da Rocha

    2015-04-01

    Full Text Available Biological Soil Crusts (BSCs are organosedimentary assemblages comprised of microbes and minerals in topsoil of terrestrial environments. BSCs strongly impact soil quality in dryland ecosystems (e.g., soil structure and nutrient yields due to pioneer species such as Microcoleus vaginatus; phototrophs that produce filaments that bind the soil together, and support an array of heterotrophic microorganisms. These microorganisms in turn contribute to soil stability and biogeochemistry of BSCs. Non-cyanobacterial populations of BSCs are less well known than cyanobacterial populations. Therefore, we attempted to isolate a broad range of numerically significant and phylogenetically representative BSC aerobic heterotrophs. Combining simple pre-treatments (hydration of BSCs under dark and light and isolation strategies (media with varying nutrient availability and protection from oxidative stress we recovered 402 bacterial and one fungal isolate in axenic culture, which comprised 116 phylotypes (at 97% 16S rRNA gene sequence homology, 115 bacterial and one fungal. Each medium enriched a mostly distinct subset of phylotypes, and cultivated phylotypes varied due to the BSC pre-treatment. The fraction of the total phylotype diversity isolated, weighted by relative abundance in the community, was determined by the overlap between isolate sequences and OTUs reconstructed from metagenome or metatranscriptome reads. Together, more than 8% of relative abundance of OTUs in the metagenome was represented by our isolates, a cultivation efficiency much larger than typically expected from most soils. We conclude that simple cultivation procedures combined with specific pre-treatment of samples afford a significant reduction in the culturability gap, enabling physiological and metabolic assays that rely on ecologically relevant axenic cultures.

  18. Evidence for micronutrient limitation of biological soil crusts: Importance to arid-lands restoration

    Science.gov (United States)

    Bowker, M.A.; Belnap, J.; Davidson, D.W.; Phillips, S.L.

    2005-01-01

    Desertification is a global problem, costly to national economies and human societies. Restoration of biological soil crusts (BSCs) may have an important role to play in the reversal of desertification due to their ability to decrease erosion and enhance soil fertility. To determine if there is evidence that lower fertility may hinder BSC recolonization, we investigated the hypothesis that BSC abundance is driven by soil nutrient concentrations. At a regional scale (north and central Colorado Plateau, USA), moss and lichen cover and richness are correlated with a complex water-nutrient availability gradient and have approximately six-fold higher cover and approximately two-fold higher species richness on sandy soils than on shale-derived soils. At a microscale, mosses and lichens are overrepresented in microhabitats under the north sides of shrub canopies, where water and nutrients are more available. At two spatial scales, and at the individual species and community levels, our data are consistent with the hypothesis that distributions of BSC organisms are determined largely by soil fertility. The micronutrients Mn and Zn figured prominently and consistently in the various analyses, strongly suggesting that these elements are previously unstudied limiting factors in BSC development. Structural-equation modeling of our data is most consistent with the hypothesis of causal relationships between the availability of micronutrients and the abundance of the two major nitrogen (N) fixers of BSCs. Specifically, higher Mn availability may determine greater Collema tenax abundance, and both Mn and Zn may limit Collema coccophorum; alternative causal hypotheses were less consistent with the data. We propose experimental trials of micronutrient addition to promote the restoration of BSC function on disturbed lands. Arid lands, where BSCs are most prevalent, cover ???40% of the terrestrial surface of the earth; thus the information gathered in this study is potentially useful

  19. Estimating Net Photosynthesis of Biological Soil Crusts in the Atacama Using Hyperspectral Remote Sensing

    Directory of Open Access Journals (Sweden)

    Lukas W. Lehnert

    2018-06-01

    Full Text Available Biological soil crusts (BSC encompassing green algae, cyanobacteria, lichens, bryophytes, heterotrophic bacteria and microfungi are keystone species in arid environments because of their role in nitrogen- and carbon-fixation, weathering and soil stabilization, all depending on the photosynthesis of the BSC. Despite their importance, little is known about the BSCs of the Atacama Desert, although especially crustose chlorolichens account for a large proportion of biomass in the arid coastal zone, where photosynthesis is mainly limited due to low water availability. Here, we present the first hyperspectral reflectance data for the most wide-spread BSC species of the southern Atacama Desert. Combining laboratory and field measurements, we establish transfer functions that allow us to estimate net photosynthesis rates for the most common BSC species. We found that spectral differences among species are high, and differences between the background soil and the BSC at inactive stages are low. Additionally, we found that the water absorption feature at 1420 nm is a more robust indicator for photosynthetic activity than the chlorophyll absorption bands. Therefore, we conclude that common vegetation indices must be taken with care to analyze the photosynthesis of BSC with multispectral data.

  20. Biological Soil Crusts of Arctic Svalbard—Water Availability as Potential Controlling Factor for Microalgal Biodiversity

    Directory of Open Access Journals (Sweden)

    Nadine Borchhardt

    2017-08-01

    Full Text Available In the present study the biodiversity of biological soil crusts (BSCs formed by phototrophic organisms were investigated on Arctic Svalbard (Norway. These communities exert several important ecological functions and constitute a significant part of vegetation at high latitudes. Non-diatom eukaryotic microalgal species of BSCs from 20 sampling stations around Ny-Ålesund and Longyearbyen were identified by morphology using light microscopy, and the results revealed a high species richness with 102 species in total. 67 taxa belonged to Chlorophyta (31 Chlorophyceae and 36 Trebouxiophyceae, 13 species were Streptophyta (11 Klebsormidiophyceae and two Zygnematophyceae and 22 species were Ochrophyta (two Eustigmatophyceae and 20 Xanthophyceae. Surprisingly, Klebsormidium strains belonging to clade G (Streptophyta, which were so far described from Southern Africa, could be determined at 5 sampling stations. Furthermore, comparative analyses of Arctic and Antarctic BSCs were undertaken to outline differences in species composition. In addition, a pedological analysis of BSC samples included C, N, S, TP (total phosphorus, and pH measurements to investigate the influence of soil properties on species composition. No significant correlation with these chemical soil parameters was confirmed but the results indicated that pH might affect the BSCs. In addition, a statistically significant influence of precipitation on species composition was determined. Consequently, water availability was identified as one key driver for BSC biodiversity in Arctic regions.

  1. Biological Soil Crusts of Arctic Svalbard-Water Availability as Potential Controlling Factor for Microalgal Biodiversity.

    Science.gov (United States)

    Borchhardt, Nadine; Baum, Christel; Mikhailyuk, Tatiana; Karsten, Ulf

    2017-01-01

    In the present study the biodiversity of biological soil crusts (BSCs) formed by phototrophic organisms were investigated on Arctic Svalbard (Norway). These communities exert several important ecological functions and constitute a significant part of vegetation at high latitudes. Non-diatom eukaryotic microalgal species of BSCs from 20 sampling stations around Ny-Ålesund and Longyearbyen were identified by morphology using light microscopy, and the results revealed a high species richness with 102 species in total. 67 taxa belonged to Chlorophyta (31 Chlorophyceae and 36 Trebouxiophyceae), 13 species were Streptophyta (11 Klebsormidiophyceae and two Zygnematophyceae) and 22 species were Ochrophyta (two Eustigmatophyceae and 20 Xanthophyceae). Surprisingly, Klebsormidium strains belonging to clade G (Streptophyta), which were so far described from Southern Africa, could be determined at 5 sampling stations. Furthermore, comparative analyses of Arctic and Antarctic BSCs were undertaken to outline differences in species composition. In addition, a pedological analysis of BSC samples included C, N, S, TP (total phosphorus), and pH measurements to investigate the influence of soil properties on species composition. No significant correlation with these chemical soil parameters was confirmed but the results indicated that pH might affect the BSCs. In addition, a statistically significant influence of precipitation on species composition was determined. Consequently, water availability was identified as one key driver for BSC biodiversity in Arctic regions.

  2. Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands.

    Science.gov (United States)

    Weber, Bettina; Wu, Dianming; Tamm, Alexandra; Ruckteschler, Nina; Rodríguez-Caballero, Emilio; Steinkamp, Jörg; Meusel, Hannah; Elbert, Wolfgang; Behrendt, Thomas; Sörgel, Matthias; Cheng, Yafang; Crutzen, Paul J; Su, Hang; Pöschl, Ulrich

    2015-12-15

    Reactive nitrogen species have a strong influence on atmospheric chemistry and climate, tightly coupling the Earth's nitrogen cycle with microbial activity in the biosphere. Their sources, however, are not well constrained, especially in dryland regions accounting for a major fraction of the global land surface. Here, we show that biological soil crusts (biocrusts) are emitters of nitric oxide (NO) and nitrous acid (HONO). Largest fluxes are obtained by dark cyanobacteria-dominated biocrusts, being ∼20 times higher than those of neighboring uncrusted soils. Based on laboratory, field, and satellite measurement data, we obtain a best estimate of ∼1.7 Tg per year for the global emission of reactive nitrogen from biocrusts (1.1 Tg a(-1) of NO-N and 0.6 Tg a(-1) of HONO-N), corresponding to ∼20% of global nitrogen oxide emissions from soils under natural vegetation. On continental scales, emissions are highest in Africa and South America and lowest in Europe. Our results suggest that dryland emissions of reactive nitrogen are largely driven by biocrusts rather than the underlying soil. They help to explain enigmatic discrepancies between measurement and modeling approaches of global reactive nitrogen emissions. As the emissions of biocrusts strongly depend on precipitation events, climate change affecting the distribution and frequency of precipitation may have a strong impact on terrestrial emissions of reactive nitrogen and related climate feedback effects. Because biocrusts also account for a large fraction of global terrestrial biological nitrogen fixation, their impacts should be further quantified and included in regional and global models of air chemistry, biogeochemistry, and climate.

  3. Water repellency and infiltration of biological soil crusts on an arid and a temperate dunes

    Science.gov (United States)

    Fischer, Thomas; Yair, Aaron; Geppert, Helmut; Veste, Maik

    2014-05-01

    Biological soil crusts (BSCs) play an important role in many ecosystems and in all climates. We studies hydrological properties of BSCs under arid and temperate climates. The arid study site was located near Nizzana, in the northwestern Negev, Israel and the temperate site was near Lieberose, Brandenburg, Germany. BSCs were sampled at each site near the dune crest, at the center of the dune slope and at the dune base. Using principal component analysis (PCA), we studied the relationships between hydraulic properties and the molecular structure of organic matter using repellency indices, microinfiltrometry, and 13C-CP/MAS-NMR. The soil texture was finer and water holding capacities (WHCs) were higher in Nizzana, whereas surface wettability was reduced in Lieberose. At both sites, BSCs caused extra WHC compared to the mineral substrate. Infiltration after wetting along both catenas generally reached a maximum after 10 min and decreased after 30 min. Carbohydrates were the dominating components in all of the BSCs studied, where the relative peak areas of carbohydrate-derived structures (60-110 ppm) amounted to 28-46% and to 10-14% of total C-peak areas, respectively. PCA revealed that the WHC of the substrate was closely related to the amount of silt and clay, whereas the BSC induced extra WHC was closely related to carbohydrates. It was further found that water repellency was positively related to carbohydrate C, but negatively related to alkyl C. Infiltration kinetics was attributed to polysaccharide hydration and swelling. Our findings support the hypothesis that hydraulic properties of BSCs are determined by extracellular polymeric substances (EPS) and soil texture. Hydraulic properties in BSCs result from the combination of chemical properties related to C compounds mainly dominated by carbohydrates and physical surface properties related to texture, porosity and water holding capacity. References Fischer, T., Yair, A., Veste, M., Geppert, H. (2013) Hydraulic

  4. Biological soil crust effects must be included to accurately model infiltration and erosion in drylands : an example from Tabernas Badlands

    NARCIS (Netherlands)

    Rodriguez-Caballero, E.; Canton, Y.; Jetten, V.G.

    2015-01-01

    In dryland ecosystems, runoff is mainly generated in bare areas, which are also more susceptible to water erosion than vegetated areas. These bare areas are often covered and protected by biological soil crusts (BSCs), which modify numerous physicochemical surface properties involved in runoff and

  5. Biological Soil Crusts from Coastal Dunes at the Baltic Sea: Cyanobacterial and Algal Biodiversity and Related Soil Properties.

    Science.gov (United States)

    Schulz, Karoline; Mikhailyuk, Tatiana; Dreßler, Mirko; Leinweber, Peter; Karsten, Ulf

    2016-01-01

    Biological soil crusts (BSCs) are known as "ecosystem-engineers" that have important, multifunctional ecological roles in primary production, in nutrient and hydrological cycles, and in stabilization of soils. These communities, however, are almost unstudied in coastal dunes of the temperate zone. Hence, for the first time, the biodiversity of cyanobacterial and algal dominated BSCs collected in five dunes from the southern Baltic Sea coast on the islands Rügen and Usedom (Germany) was investigated in connection with physicochemical soil parameters. The species composition of cyanobacteria and algae was identified with direct determination of crust subsamples, cultural methods, and diatom slides. To investigate the influence of soil properties on species composition, the texture, pH, electrical conductivity, carbonate content, total contents of carbon, nitrogen, phosphorus, and the bioavailable phosphorus-fraction (PO4 (3-)) were analyzed in adjacent BSC-free surface soils at each study site. The data indicate that BSCs in coastal dunes of the southern Baltic Sea represent an ecologically important vegetation form with a surprisingly high site-specific diversity of 19 cyanobacteria, 51 non-diatom algae, and 55 diatoms. All dominant species of the genera Coleofasciculus, Lyngbya, Microcoleus, Nostoc, Hydrocoryne, Leptolyngbya, Klebsormidium, and Lobochlamys are typical aero-terrestrial cyanobacteria and algae, respectively. This first study of coastal sand dunes in the Baltic region provides compelling evidence that here the BSCs were dominated by cyanobacteria, algae, or a mixture of both. Among the physicochemical soil properties, the total phosphorus content of the BSC-free sand was the only factor that significantly influenced the cyanobacterial and algal community structure of BSCs in coastal dunes.

  6. Cyanobacteria inhabiting biological soil crusts of a polar desert: Sør Rondane Mountains, Antarctica.

    Science.gov (United States)

    Pushkareva, Ekaterina; Pessi, Igor S; Namsaraev, Zorigto; Mano, Marie-Jose; Elster, Josef; Wilmotte, Annick

    2018-02-07

    Molecular and morphological methods were applied to study cyanobacterial community composition in biological soil crusts (BSCs) from four areas (two nunataks and two ridges) in the Sør Rondane Mountains, Antarctica. The sampling sites serve as control areas for open top chambers (OTCs) that were put in place in 2010 at the time of sample collection and will be compared with BSC samples taken from the OTCs in the future. Cyanobacterial cell biovolume was estimated using epifluorescence microscopy, which revealed the dominance of filamentous cyanobacteria in all studied sites except the Utsteinen ridge, where unicellular cyanobacteria were the most abundant. Cyanobacterial diversity was studied by a combination of molecular fingerprinting methods based on the 16S rRNA gene (denaturing gradient gel electrophoresis (DGGE) and 454 pyrosequencing) using cyanobacteria-specific primers. The number of DGGE sequences obtained per site was variable and, therefore, a high-throughput method was subsequently employed to improve the diversity coverage. Consistent with previous surveys in Antarctica, both methods showed that filamentous cyanobacteria, such as Leptolyngbya sp., Phormidium sp. and Microcoleus sp., were dominant in the studied sites. In addition, the studied localities differed in substrate type, climatic conditions and soil parameters, which probably resulted in differences in cyanobacterial community composition. Furthermore, the BSC growing on gneiss pebbles had lower cyanobacterial abundances than BSCs associated with granitic substrates. Copyright © 2018 Elsevier GmbH. All rights reserved.

  7. Climate change and physical disturbance cause similar community shifts in biological soil crusts

    Science.gov (United States)

    Ferrenberg, Scott; Reed, Sasha C.; Belnap, Jayne

    2015-01-01

    Biological soil crusts (biocrusts)—communities of mosses, lichens, cyanobacteria, and heterotrophs living at the soil surface—are fundamental components of drylands worldwide, and destruction of biocrusts dramatically alters biogeochemical processes, hydrology, surface energy balance, and vegetation cover. While there has been long-standing concern over impacts of 5 physical disturbances on biocrusts (e.g., trampling by livestock, damage from vehicles), there is also increasing concern over the potential for climate change to alter biocrust community structure. Using long-term data from the Colorado Plateau, USA, we examined the effects of 10 years of experimental warming and altered precipitation (in full-factorial design) on biocrust communities, and compared the effects of altered climate with those of long-term physical 10 disturbance (>10 years of replicated human trampling). Surprisingly, altered climate and physical disturbance treatments had similar effects on biocrust community structure. Warming, altered precipitation frequency [an increase of small (1.2 mm) summer rainfall events], and physical disturbance from trampling all promoted early successional community states marked by dramatic declines in moss cover and increased cyanobacteria cover, with more variable effects 15 on lichens. While the pace of community change varied significantly among treatments, our results suggest that multiple aspects of climate change will affect biocrusts to the same degree as physical disturbance. This is particularly disconcerting in the context of warming, as temperatures for drylands are projected to increase beyond those imposed by the climate treatments used in our study.

  8. Recovery of biological soil crust richness and cover 12–16 years after wildfires in Idaho, USA

    OpenAIRE

    H. T. Root; J. C. Brinda; E. K. Dodson

    2017-01-01

    Changing fire regimes in western North America may impact biological soil crust (BSC) communities that influence many ecosystem functions, such as soil stability and C and N cycling. However, longer-term effects of wildfire on BSC abundance, species richness, functional groups, and ecosystem functions after wildfire (i.e., BSC resilience) are still poorly understood. We sampled BSC lichen and bryophyte communities at four sites in Idaho, USA, within foothill steppe commu...

  9. Biological soil crusts exhibit a dynamic response to seasonal rain and release from grazing with implications for soil stability

    Science.gov (United States)

    Jimenez, Aguilar A.; Huber-Sannwald, E.; Belnap, J.; Smart, D.R.; Arredondo, Moreno J.T.

    2009-01-01

    In Northern Mexico, long-term grazing has substantially degraded semiarid landscapes. In semiarid systems, ecological and hydrological processes are strongly coupled by patchy plant distribution and biological soil crust (BSC) cover in plant-free interspaces. In this study, we asked: 1) how responsive are BSC cover/composition to a drying/wetting cycle and two-year grazing removal, and 2) what are the implications for soil erosion? We characterized BSC morphotypes and their influence on soil stability under grazed/non-grazed conditions during a dry and wet season. Light- and dark-colored cyanobacteria were dominant at the plant tussock and community level. Cover changes in these two groups differed after a rainy season and in response to grazing removal. Lichens with continuous thalli were more vulnerable to grazing than those with semi-continuous/discontinuous thalli after the dry season. Microsites around tussocks facilitated BSC colonization compared to interspaces. Lichen and cyanobacteria morphotypes differentially enhanced resistance to soil erosion; consequently, surface soil stability depends on the spatial distribution of BSC morphotypes, suggesting soil stability may be as dynamic as changes in the type of BSC cover. Longer-term spatially detailed studies are necessary to elicit spatiotemporal dynamics of BSC communities and their functional role in biotically and abiotically variable environments. ?? 2009 Elsevier Ltd.

  10. How biological crusts are stabilizing the soil surface? The devolpment of organo-mineral interactions in the initial phase

    Science.gov (United States)

    Fischer, T.; Veste, M.; Wiehe, W.; Lange, P.

    2009-04-01

    First colonizers of new land surfaces are cryptogames which often form biological soil crusts (BSC) covering the first millimetre of the top soil in many ecosystems from polar to desert ecosystems. These BSC are assemblages of cyanobacteria, green algae, mosses, liverworts, fungi and/or lichens. The development of soil surface crusts plays a major role for the further vegetation pattern through changes to the physico-chemical conditions and influencing various ecosystem processes. We studied the development of BSC on quaternary substrate of an initial artificial water catchment in Lusatia, Germany. Due to lack of organic matter in the geological substrate, photoautotrophic organisms like green algae and cyanobacteria dominated the initial phases of ecosystem development and, hence, of organo-mineral ineractions. We combined SEM/EDX and FTIR microscopy to study the contact zone of extracellular polymeric substances (EPS) of green algae and cyanobacteria with quartz, spars and mica on a >40 µm scale in undisturbed biological soil crusts, which had a maximum thickness of approx. 2 mm. SEM/EDX microscopy was used to determine the spatial distribution of S, Ca, Fe, Al, Si and K in the profiles, organic compounds were identified using FTIR microscopy. Exudates of crust organisms served as cementing material between sand particles. The crust could be subdivided into two horizontal layers. The upper layer, which had a thickness of approx. 200 µm, is characterized by accumulation of Al and K, but absence of Fe in microbial derived organic matter, indicating capture of weathering products of feldspars and mica by microbial exudates. The pore space between mineral particles was entirely filled with organic matter here. The underlying layer can be characterized by empty pores and organo-mineral bridges between the sand particles. Contrarily to the upper layer of the crust, Fe, Al and Si were associated with organic matter here but K was absent. Highest similarity of the FTIR

  11. Carbon budgets of biological soil crusts at micro-, meso-, and global scales

    Science.gov (United States)

    Sancho, Leopoldo G; Belnap, Jayne; Colesie, Claudia; Raggio, Jose; Weber, Bettina

    2016-01-01

    The importance of biocrusts in the ecology of arid lands across all continents is widely recognized. In spite of this broad distribution, contributions of biocrusts to the global biogeochemical cycles have only recently been considered. While these studies opened a new view on the global role of biocrusts, they also clearly revealed the lack of data for many habitats and of overall standards for measurements and analysis. In order to understand carbon cycling in biocrusts and the progress which has been made during the last 15 years, we offer a multi-scale approach covering different climatic regions. We also include a discussion on available measurement techniques at each scale: A micro-scale section focuses on the individual organism level, including modeling based on the combination of field and lab data. The meso-scale section addresses the CO2 exchange of a complete ecosystem or at the community level. Finally, we consider the contribution of biocrusts at a global scale, giving a general perspective of the most relevant findings regarding the role of biological soil crusts in the global terrestrial carbon cycle.

  12. Biological soil crusts (biocrusts) as a model system in community, landscape and ecosystem ecology

    Science.gov (United States)

    Bowker, Matthew A.; Maestre, Fernando T.; Eldridge, David; Belnap, Jayne; Castillo-Monroy, Andrea; Escolar, Cristina; Soliveres, Santiago

    2014-01-01

    Model systems have had a profound influence on the development of ecological theory and general principles. Compared to alternatives, the most effective models share some combination of the following characteristics: simpler, smaller, faster, general, idiosyncratic or manipulable. We argue that biological soil crusts (biocrusts) have unique combinations of these features that should be more widely exploited in community, landscape and ecosystem ecology. In community ecology, biocrusts are elucidating the importance of biodiversity and spatial pattern for maintaining ecosystem multifunctionality due to their manipulability in experiments. Due to idiosyncrasies in their modes of facilitation and competition, biocrusts have led to new models on the interplay between environmental stress and biotic interactions and on the maintenance of biodiversity by competitive processes. Biocrusts are perhaps one of the best examples of micro-landscapes—real landscapes that are small in size. Although they exhibit varying patch heterogeneity, aggregation, connectivity and fragmentation, like macro-landscapes, they are also compatible with well-replicated experiments (unlike macro-landscapes). In ecosystem ecology, a number of studies are imposing small-scale, low cost manipulations of global change or state factors in biocrust micro-landscapes. The versatility of biocrusts to inform such disparate lines of inquiry suggests that they are an especially useful model system that can enable researchers to see ecological principles more clearly and quickly.

  13. Ecology and functional roles of biological soil crusts in semi-arid ecosystems of Spain

    Science.gov (United States)

    Maestre, Fernando T.; Bowker, Matthew A.; Cantón, Yolanda; Castillo-Monroy, Andrea P.; Cortina, Jordi; Escolar, Cristina; Escudero, Adrián; Lázaro, Roberto; Martínez, Isabel

    2015-01-01

    Biological soil crusts (BSCs), composed of lichens, cyanobacteria, mosses, liverworts and microorganisms, are key biotic components of arid and semi-arid ecosystems worldwide. Despite they are widespread in Spain, these organisms have been historically understudied in this country. This trend is beginning to change as a recent wave of research has been identifying BSCs as a model ecological system. Many studies and research projects carried out in Spain have explored the role of BSCs on water, carbon and nitrogen fluxes, the interactions between BSCs and vascular plants, their dynamics after disturbances, and their response to global change, among other topics. In this article we review the growing body of research on BSCs available from semi-arid areas of Spain, highlighting its importance for increasing our knowledge on this group of organisms. We also discuss how it is breaking new ground in emerging research areas on the ecology of BSCs, and how it can be use to guide management and restoration efforts. Finally, we provide directions for future research on the ecology of BSCs in Spain and abroad. PMID:25908884

  14. Nutrient availability affects pigment production but not growth in lichens of biological soil crusts

    Science.gov (United States)

    Bowker, M.A.; Koch, G.W.; Belnap, J.; Johnson, N.C.

    2008-01-01

    Recent research suggests that micronutrients such as Mn may limit growth of slow-growing biological soil crusts (BSCs) in some of the drylands of the world. These soil surface communities contribute strongly to arid ecosystem function and are easily degraded, creating a need for new restoration tools. The possibility that Mn fertilization could be used as a restoration tool for BSCs has not been tested previously. We used microcosms in a controlled greenhouse setting to investigate the hypothesis that Mn may limit photosynthesis and consequently growth in Collema tenax, a dominant N-fixing lichen found in BSCs worldwide. We found no evidence to support our hypothesis; furthermore, addition of other nutrients (primarily P, K, and Zn) had a suppressive effect on gross photosynthesis (P = 0.05). We also monitored the growth and physiological status of our microcosms and found that other nutrients increased the production of scytonemin, an important sunscreen pigment, but only when not added with Mn (P = 0.01). A structural equation model indicated that this effect was independent of any photosynthesis-related variable. We propose two alternative hypotheses to account for this pattern: (1) Mn suppresses processes needed to produce scytonemin; and (2) Mn is required to suppress scytonemin production at low light, when it is an unnecessary photosynthate sink. Although Mn fertilization does not appear likely to increase photosynthesis or growth of Collema, it could have a role in survivorship during environmentally stressful periods due to modification of scytonemin production. Thus, Mn enrichment should be studied further for its potential to facilitate BSC rehabilitation. ?? 2008 Elsevier Ltd.

  15. Biological soil crusts across disturbance–recovery scenarios: effect of grazing regime on community dynamics.

    Science.gov (United States)

    Concostrina-Zubiri, L; Huber-Sannwald, E; Martínez, I; Flores Flores, J L; Reyes-Agüero, J A; Escude, A; Belnap, J

    Grazing represents one of the most common disturbances in drylands worldwide, affecting both ecosystem structure and functioning. Despite the efforts to understand the nature and magnitude of grazing effects on ecosystem components and processes, contrasting results continue to arise. This is particularly remarkable for the biological soil crust (BSC) communities (i.e., cyanobacteria, lichens, and bryophytes), which play an important role in soil dynamics. Here we evaluated simultaneously the effect of grazing impact on BSC communities (resistance) and recovery after livestock exclusion (resilience) in a semiarid grassland of Central Mexico. In particular, we examined BSC species distribution, species richness, taxonomical group cover (i.e., cyanobacteria, lichen, bryophyte), and composition along a disturbance gradient with different grazing regimes (low, medium, high impact) and along a recovery gradient with differently aged livestock exclosures (short-, medium-, long-term exclusion). Differences in grazing impact and time of recovery from grazing both resulted in slight changes in species richness; however, there were pronounced shifts in species composition and group cover. We found we could distinguish four highly diverse and dynamic BSC species groups: (1) species with high resistance and resilience to grazing, (2) species with high resistance but low resilience, (3) species with low resistance but high resilience, and (4) species with low resistance and resilience. While disturbance resulted in a novel diversity configuration, which may profoundly affect ecosystem functioning, we observed that 10 years of disturbance removal did not lead to the ecosystem structure found after 27 years of recovery. These findings are an important contribution to our understanding of BCS dynamics from a species and community perspective placed in a land use change context.

  16. Biological soil crusts across disturbance-recovery scenarios: effect of grazing regime on community dynamics

    Science.gov (United States)

    Concostrina-Zubiri, L.; Huber-Sannwald, E.; Martínez, I.; Flores Flores, J. L.; Reyes-Agüero, J. A.; Escudero, A.; Belnap, Jayne

    2014-01-01

    Grazing represents one of the most common disturbances in drylands worldwide, affecting both ecosystem structure and functioning. Despite the efforts to understand the nature and magnitude of grazing effects on ecosystem components and processes, contrasting results continue to arise. This is particularly remarkable for the biological soil crust (BSC) communities (i.e., cyanobacteria, lichens, and bryophytes), which play an important role in soil dynamics. Here we evaluated simultaneously the effect of grazing impact on BSC communities (resistance) and recovery after livestock exclusion (resilience) in a semiarid grassland of Central Mexico. In particular, we examined BSC species distribution, species richness, taxonomical group cover (i.e., cyanobacteria, lichen, bryophyte), and composition along a disturbance gradient with different grazing regimes (low, medium, high impact) and along a recovery gradient with differently aged livestock exclosures (short-, medium-, long-term exclusion). Differences in grazing impact and time of recovery from grazing both resulted in slight changes in species richness; however, there were pronounced shifts in species composition and group cover. We found we could distinguish four highly diverse and dynamic BSC species groups: (1) species with high resistance and resilience to grazing, (2) species with high resistance but low resilience, (3) species with low resistance but high resilience, and (4) species with low resistance and resilience. While disturbance resulted in a novel diversity configuration, which may profoundly affect ecosystem functioning, we observed that 10 years of disturbance removal did not lead to the ecosystem structure found after 27 years of recovery. These findings are an important contribution to our understanding of BCS dynamics from a species and community perspective placed in a land use change context.

  17. Functional profiles reveal unique ecological roles of various biological soil crust organisms

    Science.gov (United States)

    Bowker, M.A.; Mau, R.L.; Maestre, F.T.; Escolar, C.; Castillo-Monroy, A. P.

    2011-01-01

    1. At the heart of the body of research on biodiversity effects on ecosystem function is the debate over whether different species tend to be functionally singular or redundant. When we consider ecosystem multi-function, the provision of multiple ecosystem functions simultaneously, we may find that seemingly redundant species may in fact play unique roles in ecosystems. 2. Over the last few decades, the significance of biological soil crusts (BSCs) as ecological boundaries and ecosystem engineers, and their multi-functional nature, has become increasingly well documented. We compiled 'functional profiles' of the organisms in this understudied community, to determine whether functional singularity emerges when multiple ecosystem functions are considered. 3. In two data sets, one representing multiple sites around the semi-arid regions of Spain (regional scale), and another from a single site in central Spain (local scale), we examined correlations between the abundance or frequency of BSC species in a community, and multiple surrogates of ecosystem functioning. There was a wide array of apparent effects of species on specific functions. 4. Notably, in gypsiferous soils and at regional scale, we found that indicators of carbon (C) and phosphorus cycling were apparently suppressed and promoted by the lichens Diploschistes diacapsis and Squamarina lentigera, respectively. The moss Pleurochaete squarrosa appears to promote C cycling in calcareous soils at this spatial scale. At the local scale in gypsiferous soils, D. diacapsis positively correlated with carbon cycling, but negatively with nitrogen cycling, whereas numerous lichens exhibited the opposite profile. 5. We found a high degree of functional singularity, i.e. that species were highly individualistic in their effects on multiple functions. Many functional attributes were not easily predictable from existing functional grouping systems based primarily on morphology. 6. Our results suggest that maintaining

  18. Some Like it High! Phylogenetic Diversity of High-Elevation Cyanobacterial Community from Biological Soil Crusts of Western Himalaya.

    Science.gov (United States)

    Čapková, Kateřina; Hauer, Tomáš; Řeháková, Klára; Doležal, Jiří

    2016-01-01

    The environment of high-altitudinal cold deserts of Western Himalaya is characterized by extensive development of biological soil crusts, with cyanobacteria as dominant component. The knowledge of their taxonomic composition and dependency on soil chemistry and elevation is still fragmentary. We studied the abundance and the phylogenetic diversity of the culturable cyanobacteria and eukaryotic microalgae in soil crusts along altitudinal gradients (4600-5900 m) at two sites in the dry mountains of Ladakh (SW Tibetan Plateau and Eastern Karakoram), using both microscopic and molecular approaches. The effects of environmental factors (altitude, mountain range, and soil physico-chemical parameters) on the composition and biovolume of phototrophs were tested by multivariate redundancy analysis and variance partitioning. Both phylogenetic diversity and composition of morphotypes were similar between Karakorum and Tibetan Plateau. Phylogenetic analysis of 16S rRNA gene revealed strains belonging to at least five genera. Besides clusters of common soil genera, e.g., Microcoleus, Nodosilinea, or Nostoc, two distinct clades of simple trichal taxa were newly discovered. The most abundant cyanobacterial orders were Oscillatoriales and Nostacales, whose biovolume increased with increasing elevation, while that of Chroococales decreased. Cyanobacterial species richness was low in that only 15 morphotypes were detected. The environmental factors accounted for 52 % of the total variability in microbial data, 38.7 % of which was explained solely by soil chemical properties, 14.5 % by altitude, and 8.4 % by mountain range. The elevation, soil phosphate, and magnesium were the most important predictors of soil phototrophic communities in both mountain ranges despite their different bedrocks and origin. The present investigation represents a first record on phylogenetic diversity of the cyanobacterial community of biological soil crusts from Western Himalayas and first record

  19. Biological soil crusts are the main contributor to winter soil respiration in a temperate desert ecosystem of China

    Science.gov (United States)

    He, M. Z.

    2012-04-01

    Aims Biological soil crusts (BSCs) are a key biotic component of desert ecosystems worldwide. However, most studies carried out to date on carbon (fluxes) in these ecosystems, such as soil respiration (RS), have neglected them. Also, winter RS is reported to be a significant component of annual carbon budget in other ecosystems, however, we have less knowledge about winter RS of BSCs in winter and its contribution to carbon cycle in desert regions. Therefore, the specific objectives of this study were to: (i) quantify the effects of different BSCs types (moss crust, algae crust, physical crust) on the winter RS; (ii) explore relationships of RS against soil temperature and water content for different BSCs, and (iii) assess the relative contribution of BSCs to the annual amount of C released by RS at desert ecosystem level. Methods Site Description The study sites are located at the southeast fringe of the Tengger Desert in the Shapotou region of the Ningxia Hui Autonomous Region [37°32'N and 105°02'E, at 1340 m above mean sea level (a.m.s.l.)], western China. The mean daily temperature in January is -6.9°C , while it is 24.3°C in July. The mean annual precipitation is 186 mm, approximately 80% of which falls between May and September. The annual potential evaporation is 2800 mm. The landscape of the Shapotou region is characterized by large and dense reticulate barchans chains of sand dunes that migrate south-eastward at a velocity of 3-6 m per year. The soil is loose, infertile and mobile and can thus be classified as orthic sierozem and Aeolian sandy soil. Additionally, the soil has a consistent gravimetric water content that ranges from 3 to 4%. The groundwater in the study area is too deep (>60 m) to support large areas of the native vegetation cover; therefore, precipitation is usually the only source of freshwater. The predominant native plants are Hedysarum scoparium Fisch. and Agriophyllum squarrosum Moq., Psammochloa cillosa Bor, which scattered

  20. Bacterial diversity and community along the succession of biological soil crusts in the Gurbantunggut Desert, Northern China.

    Science.gov (United States)

    Zhang, Bingchang; Kong, Weidong; Wu, Nan; Zhang, Yuanming

    2016-06-01

    Biological soil crusts (BSCs) are common and play critical roles in semi-arid and arid ecosystems. Bacteria, as an important community in BSCs, play critical roles in biochemical processes. However, how bacterial diversity and community change in different successional stages of BSCs is still unknown. We used 454 pyrosequencing of 16S rRNA to investigate the bacterial composition and community, and the relationships between bacterial composition and environmental factors were also explored. In different successional stages of BSCs, the number of bacteria operational taxonomic units (OTUs) detected in each sample ranged from 2572 to 3157. Proteobacteria, Cyanobacteria, Bacteroidetes were dominant in BSCs, followed by Firmicutes, Acidobacteria, and Actinobacteria. At the successional stages of BSCs, bacterial communities, OTU composition and their relative abundance notably differentiated, and Cyanobacteria, especially Microcoleus vaginatus, dominated algal crust and lichen crust, and were the main C-fixing bacteria in BSCs. Proteobacteria and Bacteroidetes increased with the development of BSCs. OTUs related to Planomicrobium Chinese, Desulfobulbus sp., Desulfomicrobium sp., Arthrobacter sp., and Ahhaerbacter sp. showed higher relative abundance in bare sand than other successional stages of BSCs, while relative abundance of Sphingomonas sp. Niastella sp., Pedobacter, Candidatus solobacter, and Streptophyta increased with the development of BSCs. In successional stages of BSCs, bacterial OTUs composition demonstrated strong correlations with soil nutrients, soil salts, and soil enzymes. Additionally, variation of bacterial composition led to different ecological function. In bare sand, some species were related with mineral metabolism or promoting plant growth, and in algal crust and lichen crust, C-fixing bacteria increased and accumulated C to the desert soil. In later developed stage of BSCs, bacteria related with decomposition of organic matter, such as

  1. Germination, survival and growth of three vascular plants on biological soil crusts from a Mexican tropical desert.

    Science.gov (United States)

    Godínez-Alvarez, H; Morín, C; Rivera-Aguilar, V

    2012-01-01

    Information about the effects of biological soil crusts (BSC) on germination, seedling survival and growth of vascular plants is controversial because they can have positive, neutral or negative effects. This controversy may be because most studies conducted until now have just analysed one or two recruitment stages independently. To understand the BSC effects on vascular plants, it is necessary to consider each stage of the recruitment process and synthesise all this information. The goal of this study was twofold. First, we analyse germination, seedling survival and growth of three vascular plants (Agave marmorata, Prosopis laevigata and Neobuxbaumia tetetzo) on BSC (cyanobacteria and mixed crust) from a tropical desert region of south-central México. Second, we synthesise the information to determine the total effect of BSC on plant species performance. We conducted experiments under controlled conditions to evaluate the proportion of germinated seeds, proportion of surviving seedlings and seedling dry weight in BSC and bare soil. Results showed that BSC have different effects on germination, seedling survival and growth of plant species. Plant species performance was qualitatively higher on BSC than bare soil. The highest performance of A. marmorata and P. laevigata was observed on cyanobacteria and mixed crusts, respectively. The highest performance of N. tetetzo was on both crust types. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

  2. Responses of photosynthetic properties and chloroplast ultrastructure of two moss crusts from a desert biological soil crust to supplementary UV-B radiation

    Science.gov (United States)

    Hui, Rong; Li, Xinrong; Zhao, Yang; Pan, Yanxia

    2016-04-01

    Our understanding of plant responses to supplementary ultraviolet-B (UV-B) radiation due to stratospheric ozone depletion has improved over recent decades. However, research on biological soil crusts (BSCs) is scarce and it remains controversial. Laboratory studies were conducted to investigate the influence of UV-B radiation on the Bryum argenteum and Didymodon vinealis isolated from BSCs, which are both dominant species in moss crusts found within patches of shrubs and herbs in the Tengger Desert of northern China. The aim of the current work was to evaluate whether supplementary UV-B radiation affected photosynthetic properties and chloroplast ultrastructure of two moss crusts and whether response differences were observed between the crusts. Four levels of UV-B radiation of 2.75 (control), 3.08, 3.25, and 3.41 W m-2 was achieved using fluorescence tube systems for 10 days, simulating 0, 6, 9, and 12% of stratospheric ozone at the latitude of Shapotou, respectively. We measured photosynthetic apparatus as assessed by chlorophyll a fluorescence parameters, photosynthetic pigment contents, and observations of chloroplast ultrastructure. Additionally, soluble proteins and UV-B absorbing compounds were simultaneously investigated. The results of this study showed that chlorophyll a fluorescence parameters (i.e., the maximal quantum yield of PSII photochemistry, the effective quantum yield of PSII photochemistry, and photochemical quenching coefficient), photosynthetic pigment contents, soluble protein contents, total flavonoid contents and the ultrastructure were negatively influenced by elevated UV-B radiation and the degree of detrimental effects significantly increased with the intensity of UV-B radiation. Moreover, results demonstrated that the negative effects on photosynthesis and chloroplast ultrastructure were more serious in B. argenteum than that in D. vinealis. These results may not only provide a potential mechanism for supplemental UV-B effects on

  3. Biological soil crust as a bio-mediator alters hydrological processes in stabilized dune system of the Tengger Desert, China

    Science.gov (United States)

    Li, Xinrong

    2016-04-01

    Biological soil crust (BSC) is a vital component in the stabilized sand dunes with a living cover up to more than 70% of the total, which has been considered as a bio-mediator that directly influences and regulates the sand dune ecosystem processes. However, its influences on soil hydrological processes have been long neglected in Chinese deserts. In this study, BSCs of different successional stages were chose to test their influence on the hydrological processes of stabilized dune, where the groundwater deep exceeds 30m, further to explore why occur the sand-binding vegetation replacement between shrubs and herbs. Our long-term observation (60 years) shows that cyanobacteria crust has been colonized and developed after 3 years since the sand-binding vegetation has been established and dune fixation using planted xerophytic shrubs and made sand barrier (straw-checkerboard) on shifting dune surface, lichen and moss crust occurred after 20 years, and the cover of moss dominated crust could reach 70 % after 50 years. The colonization and development of BSC altered the initial soil water balance of revegetated areas by influencing rainfall infiltration, soil evaporation and dew water entrapment. The results show that BSC obviously reduced the infiltration that occurred during most rainfall events (80%), when rainfall was greater than 5 mm or less than 20 mm. The presence of BSC reduced evaporation of topsoil after small rainfall (<5 mm) because its high proportion of finer particles slowed the evaporation rate, thus keeping the water in the soil surface longer, and crust facilitated topsoil evaporation when rainfall reached 10 mm. The amount of dew entrapment increases with the succession of BSC. Moreover, the effect of the later successional BSC to dew entrapment, rainfall infiltration and evaporation was more obvious than the early successional BSC on stabilized dunes. In general, BSC reduced the amount of rainfall water that reached deeper soil (0.4-3m), which is

  4. Common and distinguishing features of the bacterial and fungal communities in biological soil crusts and shrub root zone soils

    Science.gov (United States)

    Steven, Blaire; Gallegos-Graves, La Verne; Yeager, Chris; Belnap, Jayne; Kuske, Cheryl R.

    2013-01-01

    Soil microbial communities in dryland ecosystems play important roles as root associates of the widely spaced plants and as the dominant members of biological soil crusts (biocrusts) colonizing the plant interspaces. We employed rRNA gene sequencing (bacterial 16S/fungal large subunit) and shotgun metagenomic sequencing to compare the microbial communities inhabiting the root zones of the dominant shrub, Larrea tridentata (creosote bush), and the interspace biocrusts in a Mojave desert shrubland within the Nevada Free Air CO2 Enrichment (FACE) experiment. Most of the numerically abundant bacteria and fungi were present in both the biocrusts and root zones, although the proportional abundance of those members differed significantly between habitats. Biocrust bacteria were predominantly Cyanobacteria while root zones harbored significantly more Actinobacteria and Proteobacteria. Pezizomycetes fungi dominated the biocrusts while Dothideomycetes were highest in root zones. Functional gene abundances in metagenome sequence datasets reflected the taxonomic differences noted in the 16S rRNA datasets. For example, functional categories related to photosynthesis, circadian clock proteins, and heterocyst-associated genes were enriched in the biocrusts, where populations of Cyanobacteria were larger. Genes related to potassium metabolism were also more abundant in the biocrusts, suggesting differences in nutrient cycling between biocrusts and root zones. Finally, ten years of elevated atmospheric CO2 did not result in large shifts in taxonomic composition of the bacterial or fungal communities or the functional gene inventories in the shotgun metagenomes.

  5. The biological soil crusts of the San Nicolas Island: Enigmatic algae from a geographically isolated ecosystem

    Science.gov (United States)

    Flechtner, V.R.; Johansen, J.R.; Belnap, J.

    2008-01-01

    Composite soil samples from 7 sites on San Nicolas Island were evaluated quantitatively and qualitatively for the presence of cyanobacteria and eukaryotic microalgae. Combined data demonstrated a rich algal flora with 19 cyanobacterial and 19 eukaryotic microalgal genera being identified, for a total of 56 species. Nine new species were identified and described among the cyanobacteria and the eukaryotic microalgae that were isolated: Leibleinia edaphica, Aphanothece maritima, Chroococcidiopsis edaphica, Cyanosarcina atroveneta, Hassallia californica, Hassallia pseudoramosissima, Microchaete terrestre, Palmellopsis californiens, and Pseudotetracystis compactis. Distinct distributional patterns of algal taxa existed among sites on the island and among soil algal floras of western North America. Some algal taxa appeared to be widely distributed across many desert regions, including Microcoleus vaginatus, Nostoc punctiforme, Nostoc paludosum, and Tolypothrix distorta, Chlorella vulgaris, Diplosphaera cf. chodatii, Myrmecia astigmatica, Myrmecia biatorellae, Hantzschia amphioxys, and Luticola mutica. Some taxa share a distinctly southern distribution with soil algae from southern Arizona, southern California, and Baja California (e.g., Scenedesmus deserticola and Eustigmatos magnus). The data presented herein support the view that the cyanobacterial and microalgal floras of soil crusts possess significant biodiversity, much of it previously undescribed.

  6. Growth responses of five desert plants as influenced by biological soil crusts from a temperate desert, China

    Science.gov (United States)

    Zhang, Yuanming; Belnap, Jayne

    2015-01-01

    In almost all dryland systems, biological soil crusts (biocrusts) coexist alongside herbaceous and woody vegetation, creating landscape mosaics of vegetated and biocrusted patches. Results from past studies on the interaction between biocrusts and vascular plants have been contradictory. In the Gurbantunggut desert, a large temperate desert in northwestern China, well-developed lichen-dominated crusts dominate the areas at the base and between the sand dunes. We examined the influence of these lichen-dominated biocrusts on the germination, growth, biomass accumulation, and elemental content of five common plants in this desert: two shrubs (Haloxylon persicum, Ephedra distachya) and three herbaceous plants (Ceratocarpus arenarius, Malcolmia africana and Lappula semiglabra) under greenhouse conditions. The influence of biocrusts on seed germination was species-specific. Biocrusts did not affect percent germination in plants with smooth seeds, but inhibited germination of seeds with appendages that reduced or eliminated contact with the soil surface or prevented seeds from slipping into soil cracks. Once seeds had germinated, biocrusts had different influences on growth of shrub and herbaceous plants. The presence of biocrusts increased concentrations of nitrogen but did not affect phosphorus or potassium in tissue of all tested species, while the uptake of the other tested nutrients was species-specific. Our study showed that biocrusts can serve as a biological filter during seed germination and also can influence growth and elemental uptake. Therefore, they may be an important trigger for determining desert plant diversity and community composition in deserts.

  7. Biological soil crust formation under artificial vegetation effect and its properties in the Mugetan sandy land, northeastern Qinghai-Tibet Plateau

    Science.gov (United States)

    Li, Y. F.; Li, Z. W.; Jia, Y. H.; Zhang, K.

    2016-08-01

    Mugetan sandy land is an inland desertification area of about 2,065 km2 in the northeastern Qinghai-Tibet Plateau. In the ecological restoration region of the Mugetan sandy land, different crusts have formed under the action of vegetation in three types of sandy soil (i.e. semi-fixed sand dune, fixed sand dune and ancient fixed aeolian sandy soil). The surface sand particle distribution, mineral component and vegetation composition of moving sand dunes and three types of sandy soil were studied in 2010-2014 to analyze the biological crust formation properties in the Mugetan sandy land and the effects of artificial vegetation. Results from this study revealed that artificial vegetation increases the clay content and encourages the development of biological curst. The fine particles (i.e. clay and humus) of the surface layer of the sand dunes increased more than 15% ten years after the artificial vegetation planting, and further increased up to 20% after one hundred years. The interaction of clay, humus, and other fine particles formed the soil aggregate structure. Meanwhile, under the vegetation effect from the microbes, algae, and moss, the sand particles stuck together and a biological crust formed. The interconnection of the partial crusts caused the sand dunes to gradually be fixed as a whole. Maintaining the integrity of the biological crust plays a vital role in fixing the sand under the crust. The precipitation and temperature conditions in the Mugetan sandy land could satisfy the demand of biological crust formation and development. If rational vegetation measures are adopted in the region with moving sand dunes, the lichen-moss-algae biological curst will form after ten years, but it still takes more time for the sand dunes to reach the nutrient enrichment state. If the biological curst is partly broken due to human activities, reasonable closure and restoration measures can shorten the restoration time of the biological crust.

  8. Increased temperature and altered summer precipitation have differential effects on biological soil crusts in a dryland ecosystem

    Science.gov (United States)

    Johnson, Shannon L.; Kuske, Cheryl R.; Carney, Travis D.; Housman, David C.; Gallegos-Graves, La Verne; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts) are common and ecologically important members of dryland ecosystems worldwide, where they stabilize soil surfaces and contribute newly fixed C and N to soils. To test the impacts of predicted climate change scenarios on biocrusts in a dryland ecosystem, the effects of a 2–3 °C increase in soil temperature and an increased frequency of smaller summer precipitation events were examined in a large, replicated field study conducted in the cold desert of the Colorado Plateau, USA. Surface soil biomass (DNA concentration), photosynthetically active cyanobacterial biomass (chlorophyll a concentration), cyanobacterial abundance (quantitative PCR assay), and bacterial community composition (16S rRNA gene sequencing) were monitored seasonally over 2 years. Soil microbial biomass and bacterial community composition were highly stratified between the 0–2 cm depth biocrusts and 5–10 cm depth soil beneath the biocrusts. The increase in temperature did not have a detectable effect on any of the measured parameters over 2 years. However, after the second summer of altered summer precipitation pattern, significant declines occurred in the surface soil biomass (avg. DNA concentration declined 38%), photosynthetic cyanobacterial biomass (avg. chlorophyll a concentration declined 78%), cyanobacterial abundance (avg. gene copies g−1 soil declined 95%), and proportion of Cyanobacteria in the biocrust bacterial community (avg. representation in sequence libraries declined 85%). Biocrusts are important contributors to soil stability, soil C and N stores, and plant performance, and the loss or reduction of biocrusts under an altered precipitation pattern associated with climate change could contribute significantly to lower soil fertility and increased erosion and dust production in dryland ecosystems at a regional scale.

  9. The role of microbial-produced extracellular polymeric matrix in the formation and survival of biological soil crusts

    Science.gov (United States)

    Rossi, Federico; Adessi, Alessandra; De Philippis, Roberto

    2016-04-01

    Biological soil crusts (BSCs) are complex communities commonly constituting organo-mineral layers in arid and semiarid environment having a major influence on these ecosystems (Belnap and Lange, 2001). They have high tolerance towards a-biotic stresses and fluctuations in moisture, illumination, salinity and nutrients. The plasticity exhibited by BSCs is hugely contributed by the presence of the extracellular polymeric matrix (EPM) that is synthesized by crustal organisms, notably cyanobacteria and microalgae. This polysaccharidic net plays key roles in biofilm relations with the surrounding constrained environment. Notably, EPM concurs in coping with water scarcity, freezing and salt stress; increases biolayers stability against erosion, and is involved in nutrient provision (Rossi and De Philippis, 2015). We conducted several investigations in a research area located in the Inner Mongolian desert (Inner Mongolia, China) where BSCs were induced over different sites through inoculation-based techniques performed in different years. Our studies were aimed at determining the role of EPM in BSC development and survival in such a hyper-arid system. This presentation will report the results concerning the role of EPM in water capture from non-rainfall sources, water maintenance at the topsoil, and in water infiltrability, the latter being a factor with important ecological implications. In additions we investigated the role of the matrix as a source of carbon for the crustal heterotrophs. Furthermore, EPM was extracted with methods optimized in our lab, aiming at removing tightly bound fractions and loosely bound fractions from BSCs having different ages. The fractions were analyzed in terms of monosaccharidic composition, and molecular weight (MW) distribution. We show how the relative amounts of uronic acids increase in the EPM with the age of the crusts, implying advantages for the community-water relations. In addition, we observed significant differences in MW

  10. Cyanobacterial populations in biological soil crusts of the northwest Negev Desert, Israel - effects of local conditions and disturbance.

    Science.gov (United States)

    Hagemann, Martin; Henneberg, Manja; Felde, Vincent J M N L; Berkowicz, Simon M; Raanan, Hagai; Pade, Nadin; Felix-Henningsen, Peter; Kaplan, Aaron

    2016-11-02

    Biological soil crusts (BSCs) fulfill numerous ecological functions in arid and semiarid areas. Cyanobacteria are important BSC organisms, which are responsible for carbon fixation, N 2 -fixation, and binding of soil via extracellular polysaccharides. The cyanobacterial populations were characterized in different sampling plots established in three experimental stations along a rainfall gradient within NW Negev Desert, Israel. Cyanobacterial crust thickness and osmolyte accumulation therein decreased in plots with lower moisture. The cyanobacterial population structure also changed in different plots. We observed an increase of subsection III cyanobacteria such as Microcoleus spp. and Leptolyngbya sp. and a decreasing proportion of strains belonging to subsections I and IV in drier areas on the rainfall gradient. This population shift was also observed in the sampling plots, which were situated at various relief positions within the sand dune experimental sites. We also characterized the cyanobacterial populations within mechanically disturbed plots. After four years, they reached between 80 and 50% of the control populations in the northern-most and southern stations, respectively. Our results suggest that the cyanobacterial population is sensitive not only to macroscale factors but may also be subject to local climate variations and that four years were insufficient for complete recovery of the cyanobacterial population. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Development of bacterial communities in biological soil crusts along a revegetation chronosequence in the Tengger Desert, northwest China

    Science.gov (United States)

    Liu, Lichao; Liu, Yubing; Zhang, Peng; Song, Guang; Hui, Rong; Wang, Zengru; Wang, Jin

    2017-08-01

    Knowledge of structure and function of microbial communities in different successional stages of biological soil crusts (BSCs) is still scarce for desert areas. In this study, Illumina MiSeq sequencing was used to assess the compositional changes of bacterial communities in different ages of BSCs in the revegetation of Shapotou in the Tengger Desert. The most dominant phyla of bacterial communities shifted with the changed types of BSCs in the successional stages, from Firmicutes in mobile sand and physical crusts to Actinobacteria and Proteobacteria in BSCs, and the most dominant genera shifted from Bacillus, Enterococcus and Lactococcus to RB41_norank and JG34-KF-361_norank. Alpha diversity and quantitative real-time polymerase chain reaction (PCR) analysis indicated that bacterial richness and abundance reached their highest levels after 15 years of BSC development. Redundancy analysis showed that silt + clay content and total K were the prime determinants of the bacterial communities of BSCs. The results suggested that bacterial communities of BSCs recovered quickly with the improved soil physicochemical properties in the early stages of BSC succession. Changes in the bacterial community structure may be an important indicator in the biogeochemical cycling and nutrient storage in early successional stages of BSCs in desert ecosystems.

  12. Dew formation and activity of biological crusts

    NARCIS (Netherlands)

    Veste, M.; Heusinkveld, B.G.; Berkowicz, S.M.; Breckle, S.W.; Littmann, T.; Jacobs, A.F.G.

    2008-01-01

    Biological soil crusts are prominent in many drylands and can be found in diverse parts of the globe including the Atacama desert, Chile, the Namib desert, Namibia, the Succulent-Karoo desert, South Africa, and the Negev desert, Israel. Because precipitation can be negligible in deserts ¿ the

  13. The Influence of Edaphic and Orographic Factors on Algal Diversity in Biological Soil Crusts on Bare Spots in the Polar and Subpolar Urals

    Science.gov (United States)

    Patova, E. N.; Novakovskaya, I. V.; Deneva, S. V.

    2018-03-01

    The influence of edaphic and orographic factors on the formation of algal diversity in biological soil crusts was studied in mountain tundras of the Polar and Subpolar Urals. Bare spots developed in the soils on different parent materials and overgrown to different extents were investigated. Overall, 221 algal species from six divisions were identified. Among them, eighty-eight taxa were new for the region studied. The Stigonema minutum, S. ocellatum, Nostoc commune, Gloeocapsopsis magma, Scytonema hofmannii, Leptolyngbya foveolarum, Pseudococcomyxa simplex, Sporotetras polydermatica species and species of the Cylindrocystis, Elliptochloris, Fischerella, Leptosira, Leptolyngbya, Myrmecia, Mesotaenium, Phormidium, Schizothrix genera were permanent components of biological soil crusts. The basis of the algal cenoses in soil crusts was composed of cosmopolitan cyanoprokaryotes, multicellular green algae with thickened covers and abundant mucus. The share of nitrogen fixers was high. The physicochemical properties of primary soils forming under the crusts of spots are described. The more important factors affecting the species composition of algae in the crusts are the elevation gradient, temperature, soil moisture, and the contents of Ca, Mg, mobile phosphorus, and total nitrogen.

  14. Advanced image processing methods as a tool to map and quantify different types of biological soil crust

    Science.gov (United States)

    Rodríguez-Caballero, Emilio; Escribano, Paula; Cantón, Yolanda

    2014-04-01

    Biological soil crusts (BSCs) modify numerous soil surface properties and affect many key ecosystem processes. As BSCs are considered one of the most important components of semiarid ecosystems, accurate characterisation of their spatial distribution is increasingly in demand. This paper describes a novel methodology for identifying the areas dominated by different types of BSCs and quantifying their relative cover at subpixel scale in a semiarid ecosystem of SE Spain. The approach consists of two consecutive steps: (i) First, Support Vector Machine (SVM) classification to identify the main ground units, dominated by homogenous surface cover (bare soil, cyanobacteria BSC, lichen BSC, green and dry vegetation), which are of strong ecological relevance. (ii) Spectral mixture analysis (SMA) of the ground units to quantify the proportion of each type of surface cover within each pixel, to correctly characterize the complex spatial heterogeneity inherent to semiarid ecosystems. SVM classification showed very good results with a Kappa coefficient of 0.93%, discriminating among areas dominated by bare soil, cyanobacteria BSC, lichen BSC, green and dry vegetation. Subpixel relative abundance images achieved relatively high accuracy for both types of BSCs (about 80%), whereas general overestimation of vegetation was observed. Our results open the possibility of introducing the effect of presence and of relative cover of BSCs in spatially distributed hydrological and ecological models, and assessment and monitoring aimed at reducing degradation in these areas.

  15. Key Factors Controlling the Growth of Biological Soil Crusts: Towards a Protocol to Produce Biocrusts in Greenhouse Facilities

    Science.gov (United States)

    Velasco Ayuso, Sergio; María Giraldo Silva, Ana; Nelson, Corey; Barger, Nichole; Antoninka, Anita; Bowker, Matthew; Garcia-Pichel, Ferran

    2016-04-01

    Biological soil crusts (= biocrusts) are topsoil communities comprise of, but not limited to, cyanobacteria, algae, lichens, and mosses that grow intimately associated with soil particles in drylands. Biocrusts have central ecological roles in these areas as sources of carbon and nutrients, and efficiently retain water and prevent soil erosion, which improves soil structure and promotes soil fertility. However, human activities, such as cattle grazing, hiking or military training, are rapidly striking biocrusts. Although it is well known that the inoculation with cyanobacteria or lichens can enhance the recovery of biocrusts in degraded soils, little is known about the factors that control their growth rates. Using soil and inocula from four different sites located in one cold desert (Utah) and in one hot desert (New Mexico), we performed a fractional factorial experiment involving seven factors (water, light, P, N, calcium carbonate, trace metals and type of inoculum) to screen their effects on the growth of biocrusts. After four months, we measured the concentration of chlorophyll a, and we discovered that water, light and P, N or P+N were the most important factors controlling the growth of biocrusts. In the experimental treatments involving these three factors we measured a similar concentration of chlorophyll a (or even higher) to this found in the field locations. Amplification of the 16S rRNA gene segment using universal bacteria primers revealed a microbial community composition in the biocrusts grown that closely corresponds to initial measurements made on inocula. In summary, based on our success in obtaining biocrust biomass from natural communities in greenhouse facilities, without significantly changing its community composition at the phylum and cyanobacterial level, we are paving the road to propose a protocol to produce a high quality-nursed inoculum aiming to assist restoration of arid and semi-arid ecosystems affected by large-scale disturbances.

  16. Plant interactions with changes in coverage of biological soil crusts and water regime in Mu Us Sandland, China.

    Science.gov (United States)

    Gao, Shuqin; Pan, Xu; Cui, Qingguo; Hu, Yukun; Ye, Xuehua; Dong, Ming

    2014-01-01

    Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes.

  17. Elevated CO2 did not mitigate the effect of a short-term drought on biological soil crusts

    Science.gov (United States)

    Wertin, Timothy M.; Phillips, Susan L.; Reed, Sasha C.; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts) are critical components of arid and semi-arid ecosystems that contribute significantly to carbon (C) and nitrogen (N) fixation, water retention, soil stability, and seedling recruitment. While dry-land ecosystems face a number of environmental changes, our understanding of how biocrusts may respond to such perturbation remains notably poor. To determine the effect that elevated CO2 may have on biocrust composition, cover, and function, we measured percent soil surface cover, effective quantum yield, and pigment concentrations of naturally occurring biocrusts growing in ambient and elevated CO2 at the desert study site in Nevada, USA, from spring 2005 through spring 2007. During the experiment, a year-long drought allowed us to explore the interacting effects that elevated CO2 and water availability may have on biocrust cover and function. We found that, regardless of CO2 treatment, precipitation was the major regulator of biocrust cover. Drought reduced moss and lichen cover to near-zero in both ambient and elevated CO2 plots, suggesting that elevated CO2 did not alleviate water stress or increase C fixation to levels sufficient to mitigate drought-induced reduction in cover. In line with this result, lichen quantum yield and soil cyanobacteria pigment concentrations appeared more strongly dependent upon recent precipitation than CO2 treatment, although we did find evidence that, when hydrated, elevated CO2 increased lichen C fixation potential. Thus, an increase in atmospheric CO2 may only benefit biocrusts if overall climate patterns shift to create a wetter soil environment.

  18. [Biological soil crust nitrogenase activity and its responses to hydro-thermic factors in different erosion regions on the Loess Plateau, China].

    Science.gov (United States)

    Ming, Jiao; Zhao, Yun-Ge; Xu, Ming-Xiang; Yang, Li-Na; Wang, Ai-Guo

    2013-07-01

    Based on field survey, the biological soil crusts at their stable development stage were collected from the water erosion region, water-wind erosion region, and wind erosion region on the Loess Plateau, aimed to study the effects of the variations of moisture and temperature on the crusts nitrogenase activity (NA). The NA of the crusts in the erosion regions decreased in the order of water erosion region (127.7 micromol x m(-2) x h(-1)) > water-wind erosion region (34.6 micromol x m(-2) x h(-1)) > wind erosion region (6.0 micromol x m(-2) x h(-1)), and the optimal temperature for the crust nitrogen fixation was 35 degrees C, 25 degrees C, and 15 degrees C, respectively. At the optimal temperature and 100% -40% field water-holding capacity, the NA of the crusts from the water erosion and water-wind erosion regions had no significant difference. The NA of the crusts from the wind erosion region was more sensitive to the variation of moisture, showing a dramatic decline when the moisture decreased to 80% field water-holding capacity, and totally lost when the moisture decreased to 20% field water-holding capacity. The differences in the NA of the crusts from the three erosion regions and the responses of the NA to the variations of moisture and temperature were likely associated with the climate, environment, and the crust species composition.

  19. Dryland biological soil crust cyanobacteria show unexpected decreases in abundance under long-term elevated CO2

    Science.gov (United States)

    Steven, Blaire; Gallegos-Graves, La Verne; Yeager, Chris M.; Belnap, Jayne; Evans, R. David; Kuske, Cheryl R.

    2012-01-01

    Biological soil crusts (biocrusts) cover soil surfaces in many drylands globally. The impacts of 10 years of elevated atmospheric CO2 on the cyanobacteria in biocrusts of an arid shrubland were examined at a large manipulated experiment in Nevada, USA. Cyanobacteria-specific quantitative PCR surveys of cyanobacteria small-subunit (SSU) rRNA genes suggested a reduction in biocrust cyanobacterial biomass in the elevated CO2 treatment relative to the ambient controls. Additionally, SSU rRNA gene libraries and shotgun metagenomes showed reduced representation of cyanobacteria in the total microbial community. Taxonomic composition of the cyanobacteria was similar under ambient and elevated CO2 conditions, indicating the decline was manifest across multiple cyanobacterial lineages. Recruitment of cyanobacteria sequences from replicate shotgun metagenomes to cyanobacterial genomes representing major biocrust orders also suggested decreased abundance of cyanobacteria sequences across the majority of genomes tested. Functional assignment of cyanobacteria-related shotgun metagenome sequences indicated that four subsystem categories, three related to oxidative stress, were differentially abundant in relation to the elevated CO2 treatment. Taken together, these results suggest that elevated CO2 affected a generalized decrease in cyanobacteria in the biocrusts and may have favoured cyanobacteria with altered gene inventories for coping with oxidative stress.

  20. High bacterial diversity of biological soil crusts in water tracks over permafrost in the high arctic polar desert.

    Science.gov (United States)

    Steven, Blaire; Lionard, Marie; Kuske, Cheryl R; Vincent, Warwick F

    2013-01-01

    In this study we report the bacterial diversity of biological soil crusts (biocrusts) inhabiting polar desert soils at the northern land limit of the Arctic polar region (83° 05 N). Employing pyrosequencing of bacterial 16S rRNA genes this study demonstrated that these biocrusts harbor diverse bacterial communities, often as diverse as temperate latitude communities. The effect of wetting pulses on the composition of communities was also determined by collecting samples from soils outside and inside of permafrost water tracks, hill slope flow paths that drain permafrost-affected soils. The intermittent flow regime in the water tracks was correlated with altered relative abundance of phylum level taxonomic bins in the bacterial communities, but the alterations varied between individual sampling sites. Bacteria related to the Cyanobacteria and Acidobacteria demonstrated shifts in relative abundance based on their location either inside or outside of the water tracks. Among cyanobacterial sequences, the proportion of sequences belonging to the family Oscillatoriales consistently increased in relative abundance in the samples from inside the water tracks compared to those outside. Acidobacteria showed responses to wetting pulses in the water tracks, increasing in abundance at one site and decreasing at the other two sites. Subdivision 4 acidobacterial sequences tended to follow the trends in the total Acidobacteria relative abundance, suggesting these organisms were largely responsible for the changes observed in the Acidobacteria. Taken together, these data suggest that the bacterial communities of these high latitude polar biocrusts are diverse but do not show a consensus response to intermittent flow in water tracks over high Arctic permafrost.

  1. Successful lichen translocation on disturbed gypsum areas: A test with adhesives to promote the recovery of biological soil crusts

    Science.gov (United States)

    Ballesteros, M.; Ayerbe, J.; Casares, M.; Cañadas, E. M.; Lorite, J.

    2017-04-01

    The loss of biological soil crusts represents a challenge for the restoration of disturbed environments, specifically in particular substrates hosting unique lichen communities. However, the recovery of lichen species affected by mining is rarely addressed in restoration projects. Here, we evaluate the translocation of Diploschistes diacapsis, a representative species of gypsum lichen communities affected by quarrying. We tested how a selection of adhesives could improve thallus attachment to the substrate and affect lichen vitality (as CO2 exchange and fluorescence) in rainfall-simulation and field experiments. Treatments included: white glue, water, hydroseeding stabiliser, gum arabic, synthetic resin, and a control with no adhesive. Attachment differed only in the field, where white glue and water performed best. Adhesives altered CO2 exchange and fluorescence yield. Notably, wet spoils allowed thalli to bind to the substrate after drying, revealing as the most suitable option for translocation. The satisfactory results applying water on gypsum spoils are encouraging to test this methodology with other lichen species. Implementing these measures in restoration projects would be relatively easy and cost-effective. It would help not only to recover lichen species in the disturbed areas but also to take advantage of an extremely valuable biological material that otherwise would be lost.

  2. Some like it high! Phylogenetic diversity of high-elevation cyanobacterial community from biological soil crusts of Western Himalaya.

    Czech Academy of Sciences Publication Activity Database

    Čapková, K.; Hauer, T.; Řeháková, Klára; Doležal, J.

    2016-01-01

    Roč. 71, č. 1 (2016), s. 113-123 ISSN 0095-3628 Institutional support: RVO:60077344 Keywords : soil crusts * cyanobacterial diversity * Western Himalayas * high-elevation * desert * phosphorus Subject RIV: EH - Ecology, Behaviour Impact factor: 3.630, year: 2016

  3. Some Like it High! Phylogenetic Diversity of High-Elevation Cyanobacterial Community from Biological Soil Crusts of Western Himalaya

    Czech Academy of Sciences Publication Activity Database

    Čapková, Kateřina; Hauer, Tomáš; Řeháková, Klára; Doležal, Jiří

    2016-01-01

    Roč. 71, č. 1 (2016), s. 113-123 ISSN 0095-3628 R&D Projects: GA ČR GA13-13368S Institutional support: RVO:67985939 Keywords : Soil crusts * Cyanobacterial diversity * Western Himalayas Subject RIV: EH - Ecology , Behaviour Impact factor: 3.630, year: 2016

  4. Rain pulse response of soil CO2 exchange by biological soil crusts and grasslands of the semiarid Colorado Plateau, United States

    Science.gov (United States)

    Bowling, David R.; Grote, E.E.; Belnap, J.

    2011-01-01

    Biological activity in arid grasslands is strongly dependent on moisture. We examined gas exchange of biological soil crusts (biocrusts), the underlying soil biotic community, and the belowground respiratory activity of C3 and C4 grasses over 2 years in southeast Utah, USA. We used soil surface CO2 flux and the amount and carbon isotope composition (δ13C) of soil CO2 as indicators of belowground and soil surface activity. Soil respiration was always below 2 μmol m-2s-1 and highly responsive to soil moisture. When moisture was available, warm spring and summer temperature was associated with higher fluxes. Moisture pulses led to enhanced soil respiration lasting for a week or more. Biological response to rain was not simply dependent on the amount of rain, but also depended on antecedent conditions (prior moisture pulses). The short-term temperature sensitivity of respiration was very dynamic, showing enhancement within 1-2 days of rain, and diminishing each day afterward. Carbon uptake occurred by cyanobacterially dominated biocrusts following moisture pulses in fall and winter, with a maximal net carbon uptake of 0.5 μmol m-2s-1, although typically the biocrusts were a net carbon source. No difference was detected in the seasonal activity of C3 and C4 grasses, contrasting with studies from other arid regions (where warm- versus cool-season activity is important), and highlighting the unique biophysical environment of this cold desert. Contrary to other studies, the δ13C of belowground respiration in the rooting zone of each photosynthetic type did not reflect the δ13C of C3 and C4 physiology.

  5. Global change and biological soil crusts: Effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions

    Science.gov (United States)

    Belnap, J.; Phillips, S.L.; Flint, S.; Money, J.; Caldwell, M.

    2008-01-01

    Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring-fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our treatments except quantum yield, which was reduced in dark BSCs during one of three sample times and in Collema BSCs two of three sample times. There was more response to UV augmentation the second year when air temperatures were above average. Declines were seen in 21% of the measured variables, including quantum yield, chlorophyll a, UV-protective pigments, nitrogenase activity, and extracellular polysaccharides. N additions had some negative effects on light and dark BSCs, including the reduction of quantum yield, ??-carotene, nitrogenase activity, scytonemin, and xanthophylls. N addition had no effects on the Collema BSCs. When N was added to samples that had received augmented UV, there were only limited effects relative to samples that received UV without N. These results indicate that the negative effect of UV and altered precipitation on BSCs will be heightened as global temperatures increase, and that as their ability to produce UV-protective pigments is compromised, physiological functioning will be impaired. N deposition will only ameliorate UV impacts in a limited number of cases. Overall, increases in UV will likely lead to lowered productivity and increased mortality in BSCs through time, which, in turn, will reduce their ability to contribute

  6. Plant interactions with changes in coverage of biological soil crusts and water regime in Mu Us Sandland, China.

    Directory of Open Access Journals (Sweden)

    Shuqin Gao

    Full Text Available Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1 BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2 effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3 plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes.

  7. Changes in vegetation and biological soil crust communities on sand dunes stabilizing after a century of grazing on San Miguel Island, Channel Island National Park, California

    Science.gov (United States)

    Zellman, Kristine L.

    2014-01-01

    San Miguel Island is the westernmost of the California Channel Islands and one of the windiest areas on the west coast of North America. The majority of the island is covered by coastal sand dunes, which were stripped of vegetation and subsequently mobilized due to droughts and sheep ranching during the late 19th century and early 20th century. Since the removal of grazing animals, vegetation and biological soil crusts have once again stabilized many of the island's dunes. In this study, historical aerial photographs and field surveys were used to develop a chronosequence of the pattern of change in vegetation communities and biological soil crust levels of development (LOD) along a gradient of dune stabilization. Historical aerial photographs from 1929, 1954, 1977, and 2009 were georeferenced and used to delineate changes in vegetation canopy cover and active (unvegetated) dune extent among 5 historical periods (pre-1929, 1929–1954, 1954–1977, 1977–2009, and 2009–2011). During fieldwork, vegetation and biological soil crust communities were mapped along transects distributed throughout San Miguel Island's central dune field on land forms that had stabilized during the 5 time periods of interest. Analyses in a geographic information system (GIS) quantified the pattern of changes that vegetation and biological soil crust communities have exhibited on the San Miguel Island dunes over the past 80 years. Results revealed that a continuing increase in total vegetation cover and a complex pattern of change in vegetation communities have taken place on the San Miguel Island dunes since the removal of grazing animals. The highly specialized native vascular vegetation (sea rocket, dunedelion, beach-bur, and locoweed) are the pioneer stabilizers of the dunes. This pioneer community is replaced in later stages by communities that are dominated by native shrubs (coastal goldenbush, silver lupine, coyote-brush, and giant coreopsis), with apparently overlapping or

  8. Microbial Community and Biochemical Dynamics of Biological Soil Crusts across a Gradient of Surface Coverage in the Central Mojave Desert.

    Science.gov (United States)

    Mogul, Rakesh; Vaishampayan, Parag; Bashir, Mina; McKay, Chris P; Schubert, Keith; Bornaccorsi, Rosalba; Gomez, Ernesto; Tharayil, Sneha; Payton, Geoffrey; Capra, Juliana; Andaya, Jessica; Bacon, Leonard; Bargoma, Emily; Black, David; Boos, Katie; Brant, Michaela; Chabot, Michael; Chau, Danny; Cisneros, Jessica; Chu, Geoff; Curnutt, Jane; DiMizio, Jessica; Engelbrecht, Christian; Gott, Caroline; Harnoto, Raechel; Hovanesian, Ruben; Johnson, Shane; Lavergne, Britne; Martinez, Gabriel; Mans, Paul; Morales, Ernesto; Oei, Alex; Peplow, Gary; Piaget, Ryan; Ponce, Nicole; Renteria, Eduardo; Rodriguez, Veronica; Rodriguez, Joseph; Santander, Monica; Sarmiento, Khamille; Scheppelmann, Allison; Schroter, Gavin; Sexton, Devan; Stephenson, Jenin; Symer, Kristin; Russo-Tait, Tatiane; Weigel, Bill; Wilhelm, Mary B

    2017-01-01

    In this study, we expand upon the biogeography of biological soil crusts (BSCs) and provide molecular insights into the microbial community and biochemical dynamics along the vertical BSC column structure, and across a transect of increasing BSC surface coverage in the central Mojave Desert, CA, United States. Next generation sequencing reveals a bacterial community profile that is distinct among BSCs in the southwestern United States. Distribution of major phyla in the BSC topsoils included Cyanobacteria (33 ± 8%), Proteobacteria (26 ± 6%), and Chloroflexi (12 ± 4%), with Phormidium being the numerically dominant genus. Furthermore, BSC subsurfaces contained Proteobacteria (23 ± 5%), Actinobacteria (20 ± 5%), and Chloroflexi (18 ± 3%), with an unidentified genus from Chloroflexi (AKIW781, order) being numerically dominant. Across the transect, changes in distribution at the phylum ( p < 0.0439) and genus ( p < 0.006) levels, including multiple biochemical and geochemical trends ( p < 0.05), positively correlated with increasing BSC surface coverage. This included increases in (a) Chloroflexi abundance, (b) abundance and diversity of Cyanobacteria, (b) OTU-level diversity in the topsoil, (c) OTU-level differentiation between the topsoil and subsurface, (d) intracellular ATP abundances and catalase activities, and (e) enrichments in clay, silt, and varying elements, including S, Mn, Co, As, and Pb, in the BSC topsoils. In sum, these studies suggest that BSCs from regions of differing surface coverage represent early successional stages, which exhibit increasing bacterial diversity, metabolic activities, and capacity to restructure the soil. Further, these trends suggest that BSC successional maturation and colonization across the transect are inhibited by metals/metalloids such as B, Ca, Ti, Mn, Co, Ni, Mo, and Pb.

  9. Microbial Community and Biochemical Dynamics of Biological Soil Crusts across a Gradient of Surface Coverage in the Central Mojave Desert

    Directory of Open Access Journals (Sweden)

    Rakesh Mogul

    2017-10-01

    Full Text Available In this study, we expand upon the biogeography of biological soil crusts (BSCs and provide molecular insights into the microbial community and biochemical dynamics along the vertical BSC column structure, and across a transect of increasing BSC surface coverage in the central Mojave Desert, CA, United States. Next generation sequencing reveals a bacterial community profile that is distinct among BSCs in the southwestern United States. Distribution of major phyla in the BSC topsoils included Cyanobacteria (33 ± 8%, Proteobacteria (26 ± 6%, and Chloroflexi (12 ± 4%, with Phormidium being the numerically dominant genus. Furthermore, BSC subsurfaces contained Proteobacteria (23 ± 5%, Actinobacteria (20 ± 5%, and Chloroflexi (18 ± 3%, with an unidentified genus from Chloroflexi (AKIW781, order being numerically dominant. Across the transect, changes in distribution at the phylum (p < 0.0439 and genus (p < 0.006 levels, including multiple biochemical and geochemical trends (p < 0.05, positively correlated with increasing BSC surface coverage. This included increases in (a Chloroflexi abundance, (b abundance and diversity of Cyanobacteria, (b OTU-level diversity in the topsoil, (c OTU-level differentiation between the topsoil and subsurface, (d intracellular ATP abundances and catalase activities, and (e enrichments in clay, silt, and varying elements, including S, Mn, Co, As, and Pb, in the BSC topsoils. In sum, these studies suggest that BSCs from regions of differing surface coverage represent early successional stages, which exhibit increasing bacterial diversity, metabolic activities, and capacity to restructure the soil. Further, these trends suggest that BSC successional maturation and colonization across the transect are inhibited by metals/metalloids such as B, Ca, Ti, Mn, Co, Ni, Mo, and Pb.

  10. Recovery of biological soil crust richness and cover 12–16 years after wildfires in Idaho, USA

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    H. T. Root

    2017-09-01

    Full Text Available Changing fire regimes in western North America may impact biological soil crust (BSC communities that influence many ecosystem functions, such as soil stability and C and N cycling. However, longer-term effects of wildfire on BSC abundance, species richness, functional groups, and ecosystem functions after wildfire (i.e., BSC resilience are still poorly understood. We sampled BSC lichen and bryophyte communities at four sites in Idaho, USA, within foothill steppe communities that included wildfires from 12 to 16 years old. We established six plots outside each burn perimeter and compared them with six plots of varying severity within each fire perimeter at each site. BSC cover was most strongly negatively impacted by wildfire at sites that had well-developed BSC communities in adjacent unburned plots. BSC species richness was estimated to be 65 % greater in unburned plots compared with burned plots, and fire effects did not vary among sites. In contrast, there was no evidence that vascular plant functional groups or fire severity (as measured by satellite metrics differenced normalized burn ratio (dNBR or relativized differenced normalized burn ratio (RdNBR significantly affected longer-term BSC responses. Three large-statured BSC functional groups that may be important in controlling wind and water erosion (squamulose lichens, vagrant lichens, and tall turf mosses exhibited a significant decrease in abundance in burned areas relative to adjacent unburned areas. The decreases in BSC cover and richness along with decreased abundance of several functional groups suggest that wildfire can negatively impact ecosystem function in these semiarid ecosystems for at least 1 to 2 decades. This is a concern given that increased fire frequency is predicted for the region due to exotic grass invasion and climate change.

  11. Recovery of biological soil crust richness and cover 12-16 years after wildfires in Idaho, USA

    Science.gov (United States)

    Root, Heather T.; Brinda, John C.; Dodson, E. Kyle

    2017-09-01

    Changing fire regimes in western North America may impact biological soil crust (BSC) communities that influence many ecosystem functions, such as soil stability and C and N cycling. However, longer-term effects of wildfire on BSC abundance, species richness, functional groups, and ecosystem functions after wildfire (i.e., BSC resilience) are still poorly understood. We sampled BSC lichen and bryophyte communities at four sites in Idaho, USA, within foothill steppe communities that included wildfires from 12 to 16 years old. We established six plots outside each burn perimeter and compared them with six plots of varying severity within each fire perimeter at each site. BSC cover was most strongly negatively impacted by wildfire at sites that had well-developed BSC communities in adjacent unburned plots. BSC species richness was estimated to be 65 % greater in unburned plots compared with burned plots, and fire effects did not vary among sites. In contrast, there was no evidence that vascular plant functional groups or fire severity (as measured by satellite metrics differenced normalized burn ratio (dNBR) or relativized differenced normalized burn ratio (RdNBR)) significantly affected longer-term BSC responses. Three large-statured BSC functional groups that may be important in controlling wind and water erosion (squamulose lichens, vagrant lichens, and tall turf mosses) exhibited a significant decrease in abundance in burned areas relative to adjacent unburned areas. The decreases in BSC cover and richness along with decreased abundance of several functional groups suggest that wildfire can negatively impact ecosystem function in these semiarid ecosystems for at least 1 to 2 decades. This is a concern given that increased fire frequency is predicted for the region due to exotic grass invasion and climate change.

  12. Annual net primary productivity of a cyanobacteria-dominated biological soil crust in the Gulf Savannah, Queensland, Australia

    Science.gov (United States)

    Büdel, Burkhard; Williams, Wendy J.; Reichenberger, Hans

    2018-01-01

    Biological soil crusts (biocrusts) are a common element of the Queensland (Australia) dry savannah ecosystem and are composed of cyanobacteria, algae, lichens, bryophytes, fungi and heterotrophic bacteria. Here we report how the CO2 gas exchange of the cyanobacteria-dominated biocrust type from Boodjamulla National Park in the north Queensland Gulf Savannah responds to the pronounced climatic seasonality and on their quality as a carbon sink using a semi-automatic cuvette system. The dominant cyanobacteria are the filamentous species Symplocastrum purpurascens together with Scytonema sp. Metabolic activity was recorded between 1 July 2010 and 30 June 2011, during which CO2 exchange was only evident from November 2010 until mid-April 2011, representative of 23.6 % of the 1-year recording period. In November at the onset of the wet season, the first month (November) and the last month (April) of activity had pronounced respiratory loss of CO2. The metabolic active period accounted for 25 % of the wet season and of that period 48.6 % was net photosynthesis (NP) and 51.4 % dark respiration (DR). During the time of NP, net photosynthetic uptake of CO2 during daylight hours was reduced by 32.6 % due to water supersaturation. In total, the biocrust fixed 229.09 mmol CO2 m-2 yr-1, corresponding to an annual carbon gain of 2.75 g m-2 yr-1. Due to malfunction of the automatic cuvette system, data from September and October 2010 together with some days in November and December 2010 could not be analysed for NP and DR. Based on climatic and gas exchange data from November 2010, an estimated loss of 88 mmol CO2 m-2 was found for the 2 months, resulting in corrected annual rates of 143.1 mmol CO2 m-2 yr-1, equivalent to a carbon gain of 1.7 g m-2 yr-1. The bulk of the net photosynthetic activity occurred above a relative humidity of 42 %, indicating a suitable climatic combination of temperature, water availability and light intensity well above 200 µmol photons m-2 s-1

  13. Biological soil crusts: An organizing principle in dryland ecosystems (aka: the role of biocrusts in arid land hydrology)

    Science.gov (United States)

    Chamizo, Sonia; Belnap, Jayne; Elridge, David J; Issa, Oumarou M

    2016-01-01

    Biocrusts exert a strong influence on hydrological processes in drylands by modifying numerous soil properties that affect water retention and movement in soils. Yet, their role in these processes is not clearly understood due to the large number of factors that act simultaneously and can mask the biocrust effect. The influence of biocrusts on soil hydrology depends on biocrust intrinsic characteristics such as cover, composition, and external morphology, which differ greatly among climate regimes, but also on external factors as soil type, topography and vegetation distribution patterns, as well as interactions among these factors. This chapter reviews the most recent literature published on the role of biocrusts in infiltration and runoff, soil moisture, evaporation and non-rainfall water inputs (fog, dew, water absorption), in an attempt to elucidate the key factors that explain how biocrusts affect land hydrology. In addition to the crust type and site characteristics, recent studies point to the crucial importance of the type of rainfall and the spatial scale at which biocrust effects are analyzed to understand their role in hydrological processes. Future studies need to consider the temporal and spatial scale investigated to obtain more accurate generalizations on the role of biocrusts in land hydrology.

  14. The effect of lichen-dominated biological soil crusts on growth and physiological characteristics of three plant species in a temperate desert of northwest China.

    Science.gov (United States)

    Zhuang, W W; Serpe, M; Zhang, Y M

    2015-11-01

    Biocrusts (biological soil crusts) cover open spaces between vascular plants in most arid and semi-arid areas. Information on effects of biocrusts on seedling growth is controversial, and there is little information on their effects on plant growth and physiology. We examined impacts of biocrusts on growth and physiological characteristics of three habitat-typical plants, Erodium oxyrhynchum, Alyssum linifolium and Hyalea pulchella, growing in the Gurbantunggut Desert, northwest China. The influence of biocrusts on plant biomass, leaf area, leaf relative water content, photosynthesis, maximum quantum efficiency of PSII (F(v)/F(m)), chlorophyll, osmotic solutes (soluble sugars, protein, proline) and antioxidant enzymes (superoxide dismutase, catalase, peroxidase) was investigated on sites with or without biocrust cover. Biomass, leaf area, leaf water content, photosynthesis, F(v)/F(m) and chlorophyll content in crusted soils were higher than in uncrusted soils during early growth and lower later in the growth period. Soluble sugars, proline and antioxidant enzyme activity were always higher in crusted than in uncrusted soils, while soluble protein content was always lower. These findings indicate that biocrusts have different effects on these three ephemeral species during growth in this desert, primarily via effects on soil moisture, and possibly on soil nutrients. The influence of biocrusts changes during plant development: in early plant growth, biocrusts had either positive or no effect on growth and physiological parameters. However, biocrusts tended to negatively influence plants during later growth. Our results provide insights to explain why previous studies have found different effects of biocrusts on vascular plant growth. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  15. Differential Responses of Dinitrogen Fixation, Diazotrophic Cyanobacteria and Ammonia Oxidation Reveal a Potential Warming-Induced Imbalance of the N-Cycle in Biological Soil Crusts.

    Directory of Open Access Journals (Sweden)

    Xiaobing Zhou

    Full Text Available N2 fixation and ammonia oxidation (AO are the two most important processes in the nitrogen (N cycle of biological soil crusts (BSCs. We studied the short-term response of acetylene reduction assay (ARA rates, an indicator of potential N2 fixation, and AO rates to temperature (T, -5°C to 35°C in BSC of different successional stages along the BSC ecological succession and geographic origin (hot Chihuahuan and cooler Great Basin deserts. ARA in all BSCs increased with T until saturation occurred between 15 and 20°C, and declined at 30-35°C. Culture studies using cyanobacteria isolated from these crusts indicated that the saturating effect was traceable to their inability to grow well diazotrophically within the high temperature range. Below saturation, temperature response was exponential, with Q10 significantly different in the two areas (~ 5 for Great Basin BSCs; 2-3 for Chihuahuan BSCs, but similar between the two successional stages. However, in contrast to ARA, AO showed a steady increase to 30-35°C in Great Basin, and Chihuhuan BSCs showed no inhibition at any tested temperature. The T response of AO also differed significantly between Great Basin (Q10 of 4.5-4.8 and Chihuahuan (Q10 of 2.4-2.6 BSCs, but not between successional stages. Response of ARA rates to T did not differ from that of AO in either desert. Thus, while both processes scaled to T in unison until 20°C, they separated to an increasing degree at higher temperature. As future warming is likely to occur in the regions where BSCs are often the dominant living cover, this predicted decoupling is expected to result in higher proportion of nitrates in soil relative to ammonium. As nitrate is more easily lost as leachate or to be reduced to gaseous forms, this could mean a depletion of soil N over large landscapes globally.

  16. Increasing cotton stand establishment in soils prone to soil crusting

    Science.gov (United States)

    Many factors can contribute to poor cotton stand establishment, and cotton is notorious for its weak seedling vigor. Soil crusting can be a major factor hindering cotton seedling emergence in many of the cotton production regions of the US and the world. Crusting is mainly an issue in silty soils ...

  17. Evolution of Fractal Parameters through Development Stage of Soil Crust

    Science.gov (United States)

    Ospina, Abelardo; Florentino, Adriana; Tarquis, Ana Maria

    2016-04-01

    Soil surface characteristics are subjected to changes driven by several interactions between water, air, biotic and abiotic components. One of the examples of such interactions is provided through biological soil crusts (BSC) in arid and semi-arid environments. BSC are communities composed of cyanobacteria, fungi, mosses, lichens, algae and liverworts covering the soil surface and play an important role in ecosystem functioning. The characteristics and formation of these BSC influence the soil hydrological balance, control the mass of eroded sediment, increase stability of soil surface, and influence plant productivity through the modification of nitrogen and carbon cycle. The site of this work is located at Quibor and Ojo de Agua (Lara state, Venezuela). The Quibor Depression in Venezuela is a major agricultural area being at semi-arid conditions and limited drainage favor the natural process of salinization. Additionally, the extension and intensification of agriculture has led to over-exploitation of groundwater in the past 30 years (Méndoza et al., 2013). The soil microbial crust develops initially on physical crusts which are mainly generated since wetting and drying, being a recurrent feature in the Quíbor arid zone. The microbiotic crust is organic, composed of macro organisms (bryophytes and lichens) and microorganisms (cyanobacteria, fungi algae, etc.); growing on the ground, forming a thickness no greater than 3 mm. For further details see Toledo and Florentino (2009). This study focus on characterize the development stage of the BSC based on image analysis. To this end, grayscale images of different types of biological soil crust at different stages where taken, each image corresponding to an area of 12.96 cm2 with a resolution of 1024x1024 pixels (Ospina et al., 2015). For each image lacunarity and fractal dimension through the differential box counting method were calculated. These were made with the software ImageJ/Fraclac (Karperien, 2013

  18. Crusting susceptibility in some allic Colombian soils

    International Nuclear Information System (INIS)

    Arias, Dora M; Madero E E; Amezquita E

    2001-01-01

    Many lab methods were used: dry and water soil aggregates stability, instability index and erosion index and their results were related with soil characteristics like texture, Fe and Al oxides and organic matter. Soil samples collected within 0-2.5 and 2.5-5 cm of the soil surface came from terrains with many kinds of both forest and savanna intervened systems. Those results were analyzed like a completely randomized designed. It was found that significative changes in oxides content could increase soil-crusting susceptibility unless soil humus was up to was up to 4%. In this sense, pastures or its rotation with rice and leguminous offer a best alternative for intervening these natural systems. Intensive land husbandry or monocultures with low stubble soil incorporation caused an increase in physical instability at the top of soil. Dry soil stability test and instability index were most adequate for these soils

  19. The CO2 exchange of biological soil crusts in a semiarid grass-shrubland at the northern transition zone of the Negev desert, Israel

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2008-10-01

    Full Text Available Biological soil crusts (BSC contribute significantly to the soil surface cover in many dryland ecosystems. A mixed type of BSC, which consists of cyanobacteria, mosses and cyanolichens, constitutes more than 60% of ground cover in the semiarid grass-shrub steppe at Sayeret Shaked in the northern Negev Desert, Israel. This study aimed at parameterizing the carbon sink capacity of well-developed BSC in undisturbed steppe systems. Mobile enclosures on permanent soil borne collars were used to investigate BSC-related CO2 fluxes in situ and with natural moisture supply during 10 two-day field campaigns within seven months from fall 2001 to summer 2002. Highest BSC-related CO2 deposition between –11.31 and –17.56 mmol m−2 per 15 h was found with BSC activated from rain and dew during the peak of the winter rain season. Net CO2 deposition by BSC was calculated to compensate 120%, –26%, and less than 3% of the concurrent soil CO2 efflux from November–January, February–May and November–May, respectively. Thus, BSC effectively compensated soil CO2 effluxes when CO2 uptake by vascular vegetation was probably at its low point. Nighttime respiratory emission reduced daily BSC-related CO2 deposition within the period November–January by 11–123% and on average by 27%. The analysis of CO2 fluxes and water inputs from the various sources showed that the bulk of BSC-related CO2 deposition occurs during periods with frequent rain events and subsequent condensation from water accumulated in the upper soil layers. Significant BSC activity on days without detectable atmospheric water supply emphasized the importance of high soil moisture contents as additional water source for soil-dwelling BSC, whereas activity upon dew formation at low soil water contents was not of major importance for BSC-related CO2 deposition. However, dew may still be important in attaining a pre-activated status during the transition from a long "summer" anabiosis towards

  20. Exposure to predicted precipitation patterns decreases population size and alters community structure of cyanobacteria in biological soil crusts from the Chihuahuan Desert.

    Science.gov (United States)

    Fernandes, Vanessa M C; Machado de Lima, Náthali Maria; Roush, Daniel; Rudgers, Jennifer; Collins, Scott L; Garcia-Pichel, Ferran

    2018-01-01

    Cyanobacteria typically colonize the surface of arid soils, building biological soil crust (biocrusts) that provide a variety of ecosystem benefits, ranging from fertilization to stabilization against erosion. We investigated how future scenarios in precipitation anticipated for the Northern Chihuahuan Desert affected abundance and composition of biocrust cyanobacteria in two grassland ecosystems. Scenarios included a decrease in precipitation and a delay of monsoon rainfall. After three years, both treatments negatively affected cyanobacteria, although the effects of monsoon delay were milder than those of decreased precipitation. Mature biocrusts in black grama grassland suffered severe losses in cyanobacterial biomass and diversity, but compositionally simpler biocrusts in blue grama-dominated grassland maintained biomass, only suffering diversity losses. This could be partially explained by the differential sensitivity of cyanobacterial taxa: nitrogen-fixing Scytonema spp. were the most sensitive, followed by phylotypes in the Microcoleus steenstrupii complex. Microcoleus vaginatus was the least affected in all cases, but is known to be very sensitive to warming. We predict that altered precipitation will tend to prevent biocrusts from reaching successional maturity, selecting for M. vaginatus over competing M. steenstrupii, among pioneer biocrust-formers. A shift towards heat-sensitive M. vaginatus could ultimately destabilize biocrusts when precipitation changes are combined with global warming. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  1. Response of biological soil crust diazotrophs to season, altered summer precipitation and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

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    Chris M Yeager

    2012-10-01

    Full Text Available Biological soil crusts (biocrusts, which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33 Tg y-1, are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring, as well as field manipulations that increased the frequency of small-volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3x106 – 1x108 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised > 98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low and spring (high. A year-round increase of soil temperature (2 − 3 °C had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5 years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6 fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small-volume precipitation events.

  2. Response of biological soil crust diazotrophs to season, altered summer precipitation, and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Science.gov (United States)

    Yeager, Chris M.; Kuske, Cheryl R.; Carney, Travis D.; Johnson, Shannon L.; Ticknor, Lawrence O.; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts), which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33Tg y-1), are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring), as well as field manipulations that increased the frequency of small volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3×106 to 1×8 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised >98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low) and spring (high). A year-round increase of soil temperature (2–3°C) had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6-fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small volume precipitation events.

  3. Revisiting chlorophyll extraction methods in biological soil crusts - methodology for determination of chlorophyll a and chlorophyll a + b as compared to previous methods

    Science.gov (United States)

    Caesar, Jennifer; Tamm, Alexandra; Ruckteschler, Nina; Lena Leifke, Anna; Weber, Bettina

    2018-03-01

    Chlorophyll concentrations of biological soil crust (biocrust) samples are commonly determined to quantify the relevance of photosynthetically active organisms within these surface soil communities. Whereas chlorophyll extraction methods for freshwater algae and leaf tissues of vascular plants are well established, there is still some uncertainty regarding the optimal extraction method for biocrusts, where organism composition is highly variable and samples comprise major amounts of soil. In this study we analyzed the efficiency of two different chlorophyll extraction solvents, the effect of grinding the soil samples prior to the extraction procedure, and the impact of shaking as an intermediate step during extraction. The analyses were conducted on four different types of biocrusts. Our results show that for all biocrust types chlorophyll contents obtained with ethanol were significantly lower than those obtained using dimethyl sulfoxide (DMSO) as a solvent. Grinding of biocrust samples prior to analysis caused a highly significant decrease in chlorophyll content for green algal lichen- and cyanolichen-dominated biocrusts, and a tendency towards lower values for moss- and algae-dominated biocrusts. Shaking of the samples after each extraction step had a significant positive effect on the chlorophyll content of green algal lichen- and cyanolichen-dominated biocrusts. Based on our results we confirm a DMSO-based chlorophyll extraction method without grinding pretreatment and suggest the addition of an intermediate shaking step for complete chlorophyll extraction (see Supplement S6 for detailed manual). Determination of a universal chlorophyll extraction method for biocrusts is essential for the inter-comparability of publications conducted across all continents.

  4. Revisiting chlorophyll extraction methods in biological soil crusts – methodology for determination of chlorophyll a and chlorophyll a + b as compared to previous methods

    Directory of Open Access Journals (Sweden)

    J. Caesar

    2018-03-01

    Full Text Available Chlorophyll concentrations of biological soil crust (biocrust samples are commonly determined to quantify the relevance of photosynthetically active organisms within these surface soil communities. Whereas chlorophyll extraction methods for freshwater algae and leaf tissues of vascular plants are well established, there is still some uncertainty regarding the optimal extraction method for biocrusts, where organism composition is highly variable and samples comprise major amounts of soil. In this study we analyzed the efficiency of two different chlorophyll extraction solvents, the effect of grinding the soil samples prior to the extraction procedure, and the impact of shaking as an intermediate step during extraction. The analyses were conducted on four different types of biocrusts. Our results show that for all biocrust types chlorophyll contents obtained with ethanol were significantly lower than those obtained using dimethyl sulfoxide (DMSO as a solvent. Grinding of biocrust samples prior to analysis caused a highly significant decrease in chlorophyll content for green algal lichen- and cyanolichen-dominated biocrusts, and a tendency towards lower values for moss- and algae-dominated biocrusts. Shaking of the samples after each extraction step had a significant positive effect on the chlorophyll content of green algal lichen- and cyanolichen-dominated biocrusts. Based on our results we confirm a DMSO-based chlorophyll extraction method without grinding pretreatment and suggest the addition of an intermediate shaking step for complete chlorophyll extraction (see Supplement S6 for detailed manual. Determination of a universal chlorophyll extraction method for biocrusts is essential for the inter-comparability of publications conducted across all continents.

  5. Effects of nitrogen deposition and soil fertility on cover and physiology of Cladonia foliacea (Huds.) Willd., a lichen of biological soil crusts from Mediterranean Spain

    International Nuclear Information System (INIS)

    Ochoa-Hueso, Raul; Manrique, Esteban

    2011-01-01

    We are fertilizing a thicket with 0, 10, 20 and 50 kg nitrogen (N) ha -1 yr -1 in central Spain. Here we report changes in cover, pigments, pigment ratios and FvFm of the N-tolerant, terricolous, lichen Cladonia foliacea after 1-2 y adding N in order to study its potential as biomarker of atmospheric pollution. Cover tended to increase. Pigments increased with fertilization independently of the dose supplied but only significantly with soil nitrate as covariate. β-carotene/chlorophylls increased with 20-50 kg N ha -1 yr -1 (over the background) and neoxanthin/chlorophylls also increased with N. (Neoxanthin+lutein)/carotene decreased with N when nitrate and pH seasonalities were used as covariates. FvFm showed a critical load above 40 kg N ha -1 yr -1 . Water-stress, iron and copper also explained variables of lichen physiology. We conclude that this tolerant lichen could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes. - Research highlights: → We are providing evidence of the potential use of the crust-forming lichen Cladonia foliacea as biomarker of atmospheric pollution in Mediterranean ecosystems of Europe, which are understudied with regard to this topic. → Pigment concentration increased with N addition and FvFm, used as indicator of physiological status, showed a critical load above 20 kg N ha -1 y -1 . → Soil nitrate and pH were important in modulating responses to simulated N pollution and other soil parameters (micro-nutrients, water content...) also explained variables of lichen physiology. → We conclude that Cladonia foliacea could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes. - Nitrogen deposition and soil variables affect the physiology of terrestrial Mediterranean lichens.

  6. Effects of nitrogen deposition and soil fertility on cover and physiology of Cladonia foliacea (Huds.) Willd., a lichen of biological soil crusts from Mediterranean Spain

    Energy Technology Data Exchange (ETDEWEB)

    Ochoa-Hueso, Raul, E-mail: raul.ochoa@ccma.csic.e [Instituto de Recursos Naturales, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Cientificas, C/Serrano 115 bis, 28006 Madrid (Spain); Manrique, Esteban [Instituto de Recursos Naturales, Centro de Ciencias Medioambientales, Consejo Superior de Investigaciones Cientificas, C/Serrano 115 bis, 28006 Madrid (Spain)

    2011-02-15

    We are fertilizing a thicket with 0, 10, 20 and 50 kg nitrogen (N) ha{sup -1} yr{sup -1} in central Spain. Here we report changes in cover, pigments, pigment ratios and FvFm of the N-tolerant, terricolous, lichen Cladonia foliacea after 1-2 y adding N in order to study its potential as biomarker of atmospheric pollution. Cover tended to increase. Pigments increased with fertilization independently of the dose supplied but only significantly with soil nitrate as covariate. {beta}-carotene/chlorophylls increased with 20-50 kg N ha{sup -1} yr{sup -1} (over the background) and neoxanthin/chlorophylls also increased with N. (Neoxanthin+lutein)/carotene decreased with N when nitrate and pH seasonalities were used as covariates. FvFm showed a critical load above 40 kg N ha{sup -1} yr{sup -1}. Water-stress, iron and copper also explained variables of lichen physiology. We conclude that this tolerant lichen could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes. - Research highlights: We are providing evidence of the potential use of the crust-forming lichen Cladonia foliacea as biomarker of atmospheric pollution in Mediterranean ecosystems of Europe, which are understudied with regard to this topic. Pigment concentration increased with N addition and FvFm, used as indicator of physiological status, showed a critical load above 20 kg N ha{sup -1} y{sup -1}. Soil nitrate and pH were important in modulating responses to simulated N pollution and other soil parameters (micro-nutrients, water content...) also explained variables of lichen physiology. We conclude that Cladonia foliacea could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes. - Nitrogen deposition and soil variables affect the physiology of terrestrial Mediterranean lichens.

  7. Description of Deinococcus oregonensis sp. nov., from biological soil crusts in the Southwestern arid lands of the United States of America.

    Science.gov (United States)

    Gundlapally, Sathyanarayana Reddy; Garcia-Pichel, Ferran

    2017-01-01

    Biological soil crusts are distinct habitats, harbor unique prokaryotic diversity and gave an impetus to isolate novel species. In the present study, a pink-pigmented bacterium, (OR316-6 T ), was isolated from biological soil crusts using oligotrophic BG11-PGY medium. Strain OR316-6 T was Gram-positive, short rods, non-motile and non-spore forming. Cells were positive for catalase, oxidase and β-galactosidase and negative for most of the enzymatic activities. The major fatty acids present were C 16:0 , C 17:0 , and C 16:1 ω7c and contained MK-8 and MK-10 as the predominant menaquinones. The cell wall peptidoglycan was of A3β variant with L-ornithine as the diamino acid. Based on the above characteristics, strain OR316-6 T was assigned to the genus Deinococcus. The phylogenetic analysis indicated that strain OR316-6 T was closely related to D. aquatilis DSM 23025 T with a 16S rRNA gene similarity of 99.3 % and clustered with a bootstrap value of 100 %. DNA-DNA similarity between strain OR316-6 T and D. aquatilis DSM 23025 T was 37.0 % indicating that strain OR316-6 T was a novel species. Further, DNA fingerprinting of stains OR316-6 T and D. aquatilis DSM 23035 T demonstrated that both strains were related to each other with a similarity coefficient of only 0.32 and supported the species status to strain OR316-6 T . In addition, phenotypic characteristics distinguished strain OR316-6 T from D. aquatilis DSM 23025 T . Based on the cumulative differences, strain OR316-16 T exhibited with its closely related species, it was identified as a novel species and proposed the name Deinococcus oregonensis sp. nov. The type strain is D. oregonensis sp. nov. (OR316-6 T  = JCM 13503 T  = DSM 17762 T ).

  8. Differential responses of dinitrogen fixation, diazotrophic cyanobacteria and ammonia oxidation reveal a potential warming-induced imbalance of the N-cycle in biological soil crusts

    Science.gov (United States)

    Zhou, Xiaobing; Smith, Hilda J.; Giraldo Silva, Ana; Belnap, Jayne; Garcia-Pichel, Ferran

    2017-01-01

    N2 fixation and ammonia oxidation (AO) are the two most important processes in the nitrogen (N) cycle of biological soil crusts (BSCs). We studied the short-term response of acetylene reduction assay (ARA) rates, an indicator of potential N2 fixation, and AO rates to temperature (T, -5°C to 35°C) in BSC of different successional stages along the BSC ecological succession and geographic origin (hot Chihuahuan and cooler Great Basin deserts). ARA in all BSCs increased with T until saturation occurred between 15 and 20°C, and declined at 30–35°C. Culture studies using cyanobacteria isolated from these crusts indicated that the saturating effect was traceable to their inability to grow well diazotrophically within the high temperature range. Below saturation, temperature response was exponential, with Q10 significantly different in the two areas (~ 5 for Great Basin BSCs; 2–3 for Chihuahuan BSCs), but similar between the two successional stages. However, in contrast to ARA, AO showed a steady increase to 30–35°C in Great Basin, and Chihuhuan BSCs showed no inhibition at any tested temperature. The T response of AO also differed significantly between Great Basin (Q10 of 4.5–4.8) and Chihuahuan (Q10 of 2.4–2.6) BSCs, but not between successional stages. Response of ARA rates to T did not differ from that of AO in either desert. Thus, while both processes scaled to T in unison until 20°C, they separated to an increasing degree at higher temperature. As future warming is likely to occur in the regions where BSCs are often the dominant living cover, this predicted decoupling is expected to result in higher proportion of nitrates in soil relative to ammonium. As nitrate is more easily lost as leachate or to be reduced to gaseous forms, this could mean a depletion of soil N over large landscapes globally.

  9. Characteristics and management options of crusting soils in a ...

    African Journals Online (AJOL)

    ... to control the crusting. The relationship between crust thickness and soil physical and chemical properties and management practices were assessed using stepwise regression analysis. Soil crusting was largely related to soil aggregation, infiltration, fine sand fraction, cotton monocropping and crop residue incorporation.

  10. Habitat stress initiates changes in composition, CO2 gas exchange and C-allocation as life traits in biological soil crusts.

    Science.gov (United States)

    Colesie, Claudia; Green, T G Allan; Haferkamp, Ilka; Büdel, Burkhard

    2014-10-01

    Biological soil crusts (BSC) are the dominant functional vegetation unit in some of the harshest habitats in the world. We assessed BSC response to stress through changes in biotic composition, CO2 gas exchange and carbon allocation in three lichen-dominated BSC from habitats with different stress levels, two more extreme sites in Antarctica and one moderate site in Germany. Maximal net photosynthesis (NP) was identical, whereas the water content to achieve maximal NP was substantially lower in the Antarctic sites, this apparently being achieved by changes in biomass allocation. Optimal NP temperatures reflected local climate. The Antarctic BSC allocated fixed carbon (tracked using (14)CO2) mostly to the alcohol soluble pool (low-molecular weight sugars, sugar alcohols), which has an important role in desiccation and freezing resistance and antioxidant protection. In contrast, BSC at the moderate site showed greater carbon allocation into the polysaccharide pool, indicating a tendency towards growth. The results indicate that the BSC of the more stressed Antarctic sites emphasise survival rather than growth. Changes in BSC are adaptive and at multiple levels and we identify benefits and risks attached to changing life traits, as well as describing the ecophysiological mechanisms that underlie them.

  11. Characteristics and management options of crusting soils in a ...

    African Journals Online (AJOL)

    water infiltration and accelerated soil erosion resulting from soil crusting ... in a smallholder farming area of the Zambezi metamorphic belt in northern Zimbabwe ...... beans (Ricinus communi L.) in the northeastern region of Brazil. Soil and ...

  12. The physiology mechanisms on drought tolerance and adaptation of biological soil crust moss Bryum argenteum and Didymodon vinealis in Tenger Desert

    Science.gov (United States)

    Zhao, X.; Shi, Y.; Chen, C.; Jia, R.; Li, X.

    2012-04-01

    Bryum argenteum Hedw. and Didymodon vinealis Brid are two dominant moss species in the restored vegetation area in Tenger Desert, which sampled from biological soil crusts and where is an extreme drought regions. We found that they resorted to different osmotic adjustment strategies to mitigate osmotic stress. Under the gradual drought stress, both Bryum argenteum and Didymodon vinealis accumulated K+ and soluble sugar such as sucrose and trehalose. Their glycine betaine contents both decreased, while their proline content had no significant change. With enhanced drought stress, Bryum argenteum's Na+ content was low and decreased significantly, whereas Didymodon vinealis's Na+ content increased sharply and reached to a high level. We found the different of the mechanism of between active oxygen scavenging on Enzymatic and non - enzymatic system in two species moss of Bryum argenteum Hedw and Didymodon vinealis Brid under extreme drought stress. The result showed that two species of Moss of SOD activity gradually enhanced, and they have the material basis for effectively eliminates in vivo of Superoxide free radical. POD in Didymodon nigrescen and CAT in Bryum argeneum are major resistance o oxidative stress effects. The content of GSH rise with the stress also enhanced. The mechanism of finding Bryum argenteum Hedw and Didymodon vinealis Brid tolerance of dehydration ability were focus on different direction, but they are all given positive response to stress and enhance resistance. We investigated the responses of signal transduction substances to gradual drought stress in Didymodon vinealis and Bryum argenteum. The results suggested that: under gradual drought stress, the activities of TP H+-ATPase and PM H+-ATPase of Didymodon vinealis and Bryum argenteum both increased, resulting in their increase of K+ contents and turgor pressures, and triggered biosynthesis of signal transduction substances. ABA had no obvious effect in signal transduction of Bryum argenteum

  13. Spatial dynamic of mobile dunes, soil crusting and Yobe's bank ...

    African Journals Online (AJOL)

    In the fluvio-deltaic area of Kadzell, the soil crusting and the Yobe River retreat remain the major damages. The crusting area has been multiplied by more than two while the lateral migration of the Yobe bank reached near of 3 m.yr-1. This study highlights the key role of man in the process of degradation related to climate ...

  14. Soil Characteristics of Crusted outside and Subcanopy Areas of four ...

    African Journals Online (AJOL)

    The results on compaction, salinity, pH, water holding capacity, respiration and organic carbon supported the model. The crust:shrub ratio is crucial for the functioning and sustained productivity of the system. Keywords: Soil characteristics; shrub subcanopy; crust; sink-source, Negev desert [IJARD Vol.3 2002: 162-170] ...

  15. Formation and development of salt crusts on soil surfaces

    KAUST Repository

    Dai, Sheng; Shin, Hosung; Santamarina, Carlos

    2015-01-01

    The salt concentration gradually increases at the soil free surface when the evaporation rate exceeds the diffusive counter transport. Eventually, salt precipitates and crystals form a porous sodium chloride crust with a porosity of 0.43 ± 0.14. After detaching from soils, the salt crust still experiences water condensation and salt deliquescence at the bottom, brine transport across the crust driven by the humidity gradient, and continued air-side precipitation. This transport mechanism allows salt crust migration away from the soil surface at a rate of 5 μm/h forming salt domes above soil surfaces. The surface characteristics of mineral substrates and the evaporation rate affect the morphology and the crystal size of precipitated salt. In particular, substrate hydrophobicity and low evaporation rate suppress salt spreading.

  16. Formation and development of salt crusts on soil surfaces

    KAUST Repository

    Dai, Sheng

    2015-12-14

    The salt concentration gradually increases at the soil free surface when the evaporation rate exceeds the diffusive counter transport. Eventually, salt precipitates and crystals form a porous sodium chloride crust with a porosity of 0.43 ± 0.14. After detaching from soils, the salt crust still experiences water condensation and salt deliquescence at the bottom, brine transport across the crust driven by the humidity gradient, and continued air-side precipitation. This transport mechanism allows salt crust migration away from the soil surface at a rate of 5 μm/h forming salt domes above soil surfaces. The surface characteristics of mineral substrates and the evaporation rate affect the morphology and the crystal size of precipitated salt. In particular, substrate hydrophobicity and low evaporation rate suppress salt spreading.

  17. [Effects of soil crusts on surface hydrology in the semiarid Loess hilly area].

    Science.gov (United States)

    Wei, Wei; Wen, Zhi; Chen, Li-Ding; Chen, Jin; Wu, Dong-Ping

    2012-11-01

    Soil crusts are distributed extensively in the Chinese Loess Plateau and play key roles in surface hydrological processes. In this study, a typical loess hilly region in Anjiagou catchment, Dingxi city, Gansu province was selected as the study region, and soil crusts in the catchment were investigated. Then, the hydrological effect of soil crusts was studied by using multi-sampling and hydrological monitoring experiments. Several key results were shown as follows. Firstly, compared with bared soil without crust cover, soil crusts can greatly reduce the bulk density, improve the porosity of soil, and raise the holding capacity of soil moisture which ranges from 1.4 to 1.9 times of that of bared soil. Secondly, the role of soil crust on rainfall interception was very significant. Moss crust was found to be strongest on rainfall interception, followed by synantectic crusts and lichen crusts. Bared soil without covering crusts was poorest in resisting rainfall splash. Thirdly, hydrological simulation experiments indicate that soil crusts play a certain positive role in promoting the water infiltration capacity, and the mean infiltration rate of the crusted soil was 2 times higher than that of the no-crust covered soils. While the accumulated infiltrated water amounts was also far higher than that of the bared soil.

  18. Effects of crust and cracks on simulated catchment discharge and soil loss

    NARCIS (Netherlands)

    Stolte, J.; Ritsema, C.J.; Roo, de A.P.J.

    1997-01-01

    Sealing, crusting and cracking of crusts of the soil surface has been observed in many parts of the world in areas with sandy, silty and loamy soils. Sealing and crust formation occurs under the influence of rain storm and drying weather. With prolonged drying, surface crusts might crack, leading to

  19. Effects of termites on infiltration in crusted soil.

    NARCIS (Netherlands)

    Mando, A.; Stroosnijder, L.; Brussaard, L.

    1996-01-01

    In northern Burkina Faso (West Africa), a study was undertaken to explore the possibilities of restoring the infiltration capacity of crusted soils through the stimulation of termite activity. Treatments consisted of the application of a mulch of a mixture of wood and straw without insecticides

  20. Responses of photosynthetic properties and chloroplast ultrastructure of Bryum argenteum from a desert biological soil crust to elevated ultraviolet-B radiation.

    Science.gov (United States)

    Hui, Rong; Li, Xinrong; Chen, Cuiyun; Zhao, Xin; Jia, Rongliang; Liu, Lichao; Wei, Yongping

    2013-04-01

    Our understanding of plant responses to enhanced ultraviolet-B (UV-B) radiation has improved over recent decades. However, research on cryptogams is scarce and it remains controversial whether UV-B radiation causes changes in physiology related to photosynthesis. To investigate the effects of supplementary UV-B radiation on photosynthesis and chloroplast ultrastructure in Bryum argenteum Hedw., specimens were cultured for 10 days under four UV-B treatments (2.75, 3.08, 3.25 and 3.41 W m(-2) ), simulating depletion of 0% (control), 6%, 9% and 12% of stratospheric ozone at the latitude of Shapotou, a temperate desert area of northwest China. Analyses showed malondialdehyde content significantly increased, whereas chlorophyll (Chl) fluorescence parameters and Chl contents decreased with increased UV-B intensity. These results corresponded with changes in thylakoid protein complexes and chloroplast ultrastructure. Overall, enhanced UV-B radiation leads to significant decreases in photosynthetic function and serious destruction of the chloroplast ultrastructure of B. argenteum. The degree of negative influences increased with the intensity of UV-B radiation. These results may not only provide a potential mechanism for supplemental UV-B effects on photosynthesis of moss crust, but also establish a theoretical basis for further studies of adaptation and response mechanisms of desert ecosystems under future ozone depletion. Copyright © Physiologia Plantarum 2012.

  1. La costra biológica del suelo: Avances recientes en el conocimiento de su estructura y función ecológica Biological soil crusts: Recent advances in our knowledge of their structure and ecological function

    Directory of Open Access Journals (Sweden)

    ANDREA P CASTILLO-MONROY

    2011-03-01

    estructura y funcionamiento de los ecosistemas en los que se encuentran.Biological soil crusts (BSCs result from an intimate association between soil particles and cyanobacteria, algae, microfungi, lichens, and bryophytes. These crusts are widespread in many type of soils and in almost all plant communities where sunlight can reach the soil surface. However, BSCs are particulary dominant in environments with low productivity such as arid, semi-arid, alpine and polar areas. Biological soil crusts affect soil nutrient cycling, influence the local hidrological cycle, increase soil stability, and affect the establisment and performance of vascular plants. The knowledge on the biology, ecology and physiology of BSCs has substantially increased in recent years. However, there are important gaps in our knowledge concerning the influence of BSCs on biogeochemical cycles, particularly of phosphorus and carbon, as well as on many aspects related to biotic interactions among BSC components, and between these components and microorganisms, vascular plants and invertebrates. It is necessary to expand current research efforts to other parts of the world, as most studies have been conducted mainly in arid and semi-arid areas of USA, Israel, Australia and China. Of particular concern is the lack of studies from Central and South America, despite BSCs must be a key biotic component in countries such as Chile, Argentina, Peru and Mexico. With the aim of increasing the interest of the scientific community of Spanish-speaking countries about this important group of organisms, in this review we illustrate recent advances on the importance of BSCs to maintain the structure and functioning of those ecosystems in which they are present. We also highlight the main gaps in our knowledge on the ecology of these organisms, and discuss key areas for future research.

  2. Comparison of diurnal dynamics in evaporation rate between bare soil and moss-crusted soil within a revegetated desert ecosystem of northwestern China

    Science.gov (United States)

    Zhang, Ya-Feng; Wang, Xin-Ping; Pan, Yan-Xia; Hu, Rui

    2016-02-01

    Effects of biological soil crusts (BSCs) on soil evaporation is quite controversial in literature, being either facilitative or inhibitive, and therein few studies have actually conducted direct evaporation measurements. Continuous field measurements of soil water evaporation were conducted on two microlysimeters, i.e., one with sand soil collected from bare sand dune area and the other with moss-crusted soil collected from an area that was revegetated in 1956, from field capacity to dry, at the southeastern edge of the Tengger Desert. We mainly aimed to quantify the diurnal variations of evaporation rate from two soils, and further comparatively discuss the effects of BSCs on soil evaporation after revegetation. Results showed that in clear days with high soil water content (Day 1 and 2), the diurnal variation of soil evaporation rate followed the typical convex upward parabolic curve, reaching its peak around mid-day. Diurnal evaporation rate and the accumulated evaporation amount of moss-crusted soil were lower (an average of 0.90 times) than that of sand soil in this stage. However, as soil water content decreased to a moderately low level (Day 3 and 4), the diurnal evaporation rate from moss-crusted soil was pronouncedly higher (an average of 3.91 times) than that of sand soil, prolonging the duration of this higher evaporation rate stage; it was slightly higher in the final stage (Day 5 and 6) when soil moisture was very low. We conclude that the effects of moss crusts on soil evaporation vary with different evaporation stages, which is closely related to soil water content, and the variation and transition of evaporation rate between bare soil and moss-crusted soil are expected to be predicted by soil water content.

  3. Mechanical impedance of soil crusts and water content in loamy soils

    Science.gov (United States)

    Josa March, Ramon; Verdú, Antoni M. C.; Mas, Maria Teresa

    2013-04-01

    Soil crust development affects soil water dynamics and soil aeration. Soil crusts act as mechanical barriers to fluid flow and, as their mechanical impedance increases with drying, they also become obstacles to seedling emergence. As a consequence, the emergence of seedling cohorts (sensitive seeds) might be reduced. However, this may be of interest to be used as an effective system of weed control. Soil crusting is determined by several factors: soil texture, rain intensity, sedimentation processes, etc. There are different ways to characterize the crusts. One of them is to measure their mechanical impedance (MI), which is linked to their moisture level. In this study, we measured the evolution of the mechanical impedance of crusts formed by three loamy soil types (clay loam, loam and sandy clay loam, USDA) with different soil water contents. The aim of this communication was to establish a mathematical relationship between the crust water content and its MI. A saturated soil paste was prepared and placed in PVC cylinders (50 mm diameter and 10 mm height) arranged on a plastic tray. Previously the plastic tray was sprayed with a hydrophobic liquid to prevent the adherence of samples. The samples on the plastic tray were left to air-dry under laboratory conditions until their IM was measured. To measure IM, a food texture analyzer was used. The equipment incorporates a mobile arm, a load cell to apply force and a probe. The arm moves down vertically at a constant rate and the cylindrical steel probe (4 mm diameter) penetrates the soil sample vertically at a constant rate. The equipment is provided with software to store data (time, vertical distance and force values) at a rate of up to 500 points per second. Water content in crust soil samples was determined as the loss of weight after oven-drying (105°C). From the results, an exponential regression between MI and the water content was obtained (determination coefficient very close to 1). This methodology allows

  4. [Effects of bio-crust on soil microbial biomass and enzyme activities in copper mine tailings].

    Science.gov (United States)

    Chen, Zheng; Yang, Gui-de; Sun, Qing-ye

    2009-09-01

    Bio-crust is the initial stage of natural primary succession in copper mine tailings. With the Yangshanchong and Tongguanshan copper mine tailings in Tongling City of Anhui Province as test objects, this paper studied the soil microbial biomass C and N and the activities of dehydrogenase, catalase, alkaline phosphatase, and urease under different types of bio-crust. The bio-crusts improved the soil microbial biomass and enzyme activities in the upper layer of the tailings markedly. Algal crust had the best effect in improving soil microbial biomass C and N, followed by moss-algal crust, and moss crust. Soil microflora also varied with the type of bio-crust. No'significant difference was observed in the soil enzyme activities under the three types of bio-crust. Soil alkaline phosphatase activity was significantly positively correlated with soil microbial biomass and dehydrogenase and urease activities, but negatively correlated with soil pH. In addition, moss rhizoid could markedly enhance the soil microbial biomass and enzyme activities in moss crust rhizoid.

  5. Interactive effects of moss-dominated crusts and Artemisia ordosica on wind erosion and soil moisture in Mu Us sandland, China.

    Science.gov (United States)

    Yang, Yongsheng; Bu, Chongfeng; Mu, Xingmin; Shao, Hongbo; Zhang, Kankan

    2014-01-01

    To better understand the effects of biological soil crusts (BSCs) on soil moisture and wind erosion and study the necessity and feasibility of disturbance of BSCs in the Mu Us sandland, the effects of four treatments, including moss-dominated crusts alone, Artemisia ordosica alone, bare sand, and Artemisia ordosica combined with moss-dominated crusts, on rainwater infiltration, soil moisture, and annual wind erosion were observed. The major results are as follows. (1) The development of moss-dominated crusts exacerbated soil moisture consumption and had negative effects on soil moisture in the Mu Us sandland. (2) Moss-dominated crusts significantly increased soil resistance to wind erosion, and when combined with Artemisia ordosica, this effect became more significant. The contribution of moss-dominated crusts under Artemisia ordosica was significantly lower than that of moss-dominated crusts alone in sites where vegetative coverage > 50%. (3) Finally, an appropriate disturbance of moss-dominated crusts in the rainy season in sites with high vegetative coverage improved soil water environment and vegetation succession, but disturbance in sites with little or no vegetative cover should be prohibited to avoid the exacerbation of wind erosion.

  6. The diversity and abundance of bacteria and oxygenic phototrophs in saline biological desert crusts in Xinjiang, northwest China.

    Science.gov (United States)

    Li, Ke; Liu, Ruyin; Zhang, Hongxun; Yun, Juanli

    2013-07-01

    Although microorganisms, particularly oxygenic phototrophs, are known as the major players in the biogeochemical cycles of elements in desert soil ecosystems and have received extensive attention, still little is known about the effects of salinity on the composition and abundances of microbial community in desert soils. In this study, the diversity and abundance of bacteria and oxygenic phototrophs in biological desert crusts from Xinjiang province, which were under different salinity conditions, were investigated by using clone library and quantitative PCR (qPCR). The 16S rRNA gene phylogenetic analysis showed that cyanobacteria, mainly Microcoleus vagnitus of the order Oscillatoriales, were predominant in the low saline crusts, while other phototrophs, such as diatom, were the main microorganism group responsible for the oxygenic photosynthesis in the high saline crusts. Furthermore, the higher salt content in crusts may stimulate the growth of other bacteria, including Deinococcus-Thermus, Bacteroidetes, and some subdivisions of Proteobacteria (β-, γ-, and δ-Proteobacteria). The cpcBA-IGS gene analysis revealed the existence of novel M. vagnitus strains in this area. The qPCR results showed that the abundance of oxygenic phototrophs was significantly higher under lower saline condition than that in the higher saline crusts, suggesting that the higher salinity in desert crusts could suppress the numbers of total bacteria and phototrophic bacteria but did highly improve the diversity of salt-tolerant bacteria.

  7. Temporal variation in community composition, pigmentation, and Fv/Fm of desert cyanobacterial soil crusts

    Science.gov (United States)

    Bowker, M.A.; Reed, S.C.; Belnap, J.; Phillips, S.L.

    2002-01-01

    Summers on the Colorado Plateau (USA) are typified by harsh conditions such as high temperatures, brief soil hydration periods, and high UV and visible radiation. We investigated whether community composition, physiological status, and pigmentation might vary in biological soil crusts as a result of such conditions. Representative surface cores were sampled at the ENE, WSW, and top microaspects of 20 individual soil crust pedicels at a single site in Canyonlands National Park, Utah, in spring and fall of 1999. Frequency of cyanobacterial taxa, pigment concentrations, and dark adapted quantum yield (Fv/Fm) were measured for each core. The frequency of major cyanobacterial taxa was lower in the fall compared to spring. The less-pigmented cyanobacterium Microcoleus vaginatus showed significant mortality when not in the presence of Nostoc spp. and Scytonema myochrous (Dillw.) Agardh. (both synthesizers of UV radiation-linked pigments) but had little or no mortality when these species were abundant. We hypothesize that the sunscreen pigments produced by Nostoc and Scytonema in the surface of crusts protect other, less-pigmented taxa. When fall and spring samples were compared, overall cyanobacterial frequency was lower in fall, while sunscreen pigment concentrations, chlorophyll a concentration, and Fv/Fm were higher in fall. The ratio of cyanobacterial frequency/chlorophyll a concentrations was 2-3 times lower in fall than spring. Because chlorophyll a is commonly used as a surrogate measure of soil cyanobacterial biomass, these results indicate that seasonality needs to be taken into consideration. In the fall sample, most pigments associated with UV radiation protection or repair were at their highest concentrations on pedicel tops and WSW microaspects, and at their lowest concentrations on ENE microaspects. We suggest that differential pigment concentrations between microaspects are induced by varying UV radiation dosage at the soil surface on these different

  8. Effects of sand burial on dew deposition on moss soil crust in a revegetated area of the Tennger Desert, Northern China

    Science.gov (United States)

    Jia, Rong-liang; Li, Xin-rong; Liu, Li-chao; Pan, Yan-xia; Gao, Yan-hong; Wei, Yong-ping

    2014-11-01

    Sand burial and dew deposition are two fundamental phenomena profoundly influencing biological soil crusts in desert areas. However, little information is available regarding the effects of sand burial on dew deposition on biological soil crusts in desert ecosystems. In this study, we evaluated the effects of sand burial at depths of 0 (control), 0.5, 1, 2 and 4 mm on dew formation and evaporation of three dominant moss crusts in a revegetated area of the Tengger Desert (Northern China) in 2010. The results revealed that sand burial significantly decreased the amount of dew deposited on the three moss crust types by acting as a semi-insulator retarding the dew formation and evaporation rates. The changes in surface temperature cannot fully explain the variations of the formation and evaporation rates of dew by moss crusts buried by sand. The extension of dew retention time was reflected by the higher dew ratios (the ratio of dew amount at a certain time to the maximum value in a daily course) in the daytime, and may to some extent have acted as compensatory mechanisms that diminished the negative effects of the reduction of dew amount induced by sand burial of moss crusts. The resistances to reduction of dewfall caused by sand burial among the three moss crusts were also compared and it was found that Bryum argenteum crust showed the highest tolerance, followed by crusts dominated by Didymodon vinealis and Syntrichia caninervis. This sequence corresponds well with the successional order of the three moss crusts in the revegetated area, thereby suggesting that resistance to reduction of dewfall may act as one mechanism by which sand burial drives the succession of moss crusts in desert ecosystems. This side effect of dew reduction induced by sand burial on biological soil crusts should be considered in future ecosystem construction and management of desert area.

  9. Effect of Agri-SC as a soil conditioner on runoff, soil loss and crust ...

    African Journals Online (AJOL)

    xp1

    2011-10-10

    Oct 10, 2011 ... 18.50, 37.00, 55.50 and 74.00 l ha-1) on water erosion and crust strengths under laboratory conditions with three .... stability, soil micro morphological properties, response to ... meter resistance, and increased pore space and.

  10. Photosynthetic recovery and acclimation to excess light intensity in the rehydrated lichen soil crusts.

    Directory of Open Access Journals (Sweden)

    Li Wu

    Full Text Available As an important successional stage and main type of biological soil crusts (BSCs in Shapotou region of China (southeastern edge of Tengger Desert, lichen soil crusts (LSCs often suffer from many stresses, such as desiccation and excess light intensity. In this study, the chlorophyll fluorescence and CO2 exchange in the rehydrated LSCs were detected under a series of photosynthetically active radiation (PAR gradients to study the photosynthetic acclimation of LSCs. The results showed that although desiccation leaded to the loss of photosynthetic activity in LSCs, the fluorescence parameters including Fo, Fv and Fv/Fm of LSCs could be well recovered after rehydration. After the recovery of photosynthetic activity, the effective photosynthetic efficiency ΦPSII detected by Imaging PAM had declined to nearly 0 within both the lichen thallus upper and lower layers when the PAR increased to 200 μE m-2 s-1, however the net photosynthesis detected by the CO2 gas analyzer in the LSCs still appeared when the PAR increased to 1000 μE m-2 s-1. Our results indicate that LSCs acclimating to high PAR, on the one hand is ascribed to the special structure in crust lichens, making the incident light into the lichen thallus be weakened; on the other hand the massive accumulation of photosynthetic pigments in LSCs also provides a protective barrier for the photosynthetic organisms against radiation damage. Furthermore, the excessive light energy absorbed by crust lichens is also possibly dissipated by the increasing non-photochemical quenching, therefore to some extent providing some protection for LSCs.

  11. Spectroscopic surrogates of soil organic matter resilience in crusted semiarid Mediterranean ecosystems

    Science.gov (United States)

    Miralles Mellado, Isabel; Almendros, Gonzalo; Ortega, Raúl; Cantón, Yolanda; Poveda, Francisco; van Wesemael, Bas

    2016-04-01

    Arid and semiarid ecosystems represent nearly a third of the Earth's total land surface. In these ecosystems, there is a critical balance between C sequestration and biodegradation that could easily be altered due to human disturbance or global change. These ecosystems are widely characterized by the presence of biological soil crusts (BSCs) which play the most important role in the C-cycle in arid and semiarid areas. Consequently, soil organic matter (SOM) characteristics of crusted soil could readily reflect important information on the resilience of SOM in response to any global temperature increase or to inappropriate soil management practices. In this research, representative BSCs and underlying soils were studied in two different semiarid ecosystems in Southern Spain, i.e., Amoladeras (located in Cabo de Gata Natural Park), and El Cautivo (located in Tabernas desert). Chemical fractionation and characterization of the SOM in BSCs and underlying soils were carried out in order to assess not only the total amount of organic C sequestered but mainly the quality of humic-type organic fractions. After isolating the major organic fractions (particulate fraction, humic acid-like (HA), alkali-extracted fulvic acid (FA) and H3PO4-FAs), the macromolecular, HA fraction was purified and studied by derivative visible spectroscopy and resolution-enhanced infrared (IR) spectroscopy. Our results show differences in the structural characteristics of the HA-type substances, interpreted as progressive stages of diagenetic transformation of biomacromolecules. Amoladeras showed higher SOM content, and higher values of HA and HA/FA ratio than El Cautivo, with lower SOM content in BSCs and underlying soils. The latter site accumulates SOM consisting mainly of comparatively less recalcitrant organic fractions with small molecular sizes (H3PO4-FAs and FAs). Moreover HAs in samples from Amoladeras showed higher condensation and aromaticity (higher E4, lower E4/E6 ratio), pointing to

  12. Effect of Agri-SC as a soil conditioner on runoff, soil loss and crust ...

    African Journals Online (AJOL)

    This study was carried out to determine the effect of Agri-SC as a soil conditioner at different doses (0, 18.50, 37.00, 55.50 and 74.00 l ha-1) on water erosion and crust strengths under laboratory conditions with three replicates. The Agri-SC solutions were sprayed and two consecutive simulated rainfalls (60 mm h-1) were ...

  13. Cyanobacterial crusts linked to soil productivity under different grazing management practices in Northern Australia

    Science.gov (United States)

    Alchin, Bruce; Williams, Wendy

    2015-04-01

    In arid and semi-arid Australia, the central role of healthy soil ecosystems in broad-acre grazing lands may be attributed to the widespread presence of cyanobacterial crusts. In terms of soil nutrient cycling and stability their role is particularly crucial in a climate dominated by annual dry seasons and variable wet seasons. In this study, we aimed to measure the contribution of cyanobacteria to soil nutrient cycling under contrasting levels of disturbance associated with grazing management. Field sampling was carried out on six paired sites (twelve properties) located across an east-west 3,000 km transect that covered different rangeland types on grazing properties in northern Australia (Queensland, Northern Territory and Western Australia). At each location paired sites were established and two different management systems were assessed, cell-paddock rotations (25-400 ha) and continuous grazing (200-2,000 ha). Cyanobacterial soil crusts were recorded from all of the twelve sites and cyanobacteria with the capacity to fix nitrogen were found at ten of the twelve sites. The overall diversity of cyanobacteria varied from three to ten species under any type of grazing system. As field work was conducted in the dry season, it is likely that the diversity may be greater in the wet season than the initial data may indicate. The average cyanobacterial soil crust cover across soil surfaces, between grass tussocks, during the dry season was estimated to be 50.9% and, 42.6% in the early wet season. This reflected longer established crust cover (dry season) versus newly established crusts. There was a high level of variability in the biomass of cyanobacteria however; the grazing system did not have any marked effect on the biomass for any one rangeland type. The grazing system differences did not appear to significantly influence the diversity at any location except on a floodplain in the Pilbara (WA). Biological nitrogen fixation by cyanobacteria was recorded at all

  14. A review of the ecology, ecophysiology and biodiversity of microalgae in Arctic soil crusts

    Czech Academy of Sciences Publication Activity Database

    Pushkareva, E.; Johansen, J. R.; Elster, Josef

    2016-01-01

    Roč. 39, č. 12 (2016), s. 2227-2240 ISSN 0722-4060 Institutional support: RVO:67985939 Keywords : Soil crust * Arctic * Cyanobacteria and eukaryotic microalgae Subject RIV: EH - Ecology, Behaviour Impact factor: 1.949, year: 2016

  15. Cyanobacterial community composition in Arctic soil crusts at different stages of development

    Czech Academy of Sciences Publication Activity Database

    Pushkareva, E.; Pessi, I. S.; Wilmotte, A.; Elster, Josef

    2015-01-01

    Roč. 91, 12 fiv143 (2015), s. 1-10 ISSN 0168-6496 Institutional support: RVO:67985939 Keywords : soil crust * Arctic * cyanobacteria Subject RIV: EH - Ecology, Behaviour Impact factor: 3.530, year: 2015

  16. Threshold friction velocity of crusted windblown soils in the Columbia Plateau

    Science.gov (United States)

    Wind erosion processes are governed by soil physical properties and surface characteristics. Erosion is initiated when the friction velocity exceeds the threshold friction velocity (u*t) of soils. Although u*t is influenced by soil physical properties such as wetness and crusting, there is little in...

  17. Biotic soil crusts in relation to topography, cheatgrass, and fire in the Columbia Basin, Washington

    Science.gov (United States)

    Ponzetti, Jeanne; McCune, B.; Pyke, David A.

    2007-01-01

    We studied lichen and bryophyte soil crust communities in a large public grazing allotment within a sagebrush steppe ecosystem in which the biotic soil crusts are largely intact. The allotment had been rested from grazing for 12 years, but experienced an extensive series of wildfires. In the 350, 4 ?? 0.5 m plots, stratified by topographic position, we found 60 species or species groups that can be distinguished in the field with a hand lens, averaging 11.5 species groups per plot. Lichen and bryophyte soil crust communities differed among topographic positions. Draws were the most disturbed, apparently from water erosion in a narrow channel and mass wasting from the steepened sides. Presumably because of this disturbance, draws had the lowest average species richness of all the topographic strata we examined. Biotic crust species richness and cover were inversely related to cover of the invasive annual, cheatgrass (Bromus tectorum), and positively related to cover of native bunchgrasses. Integrity of the biotic crust was more strongly related to cheatgrass than to fire. In general, we observed good recovery of crusts following fire, but only in those areas dominated by perennial bunchgrasses. We interpret the resilience of the biotic crust, in this case, to the low abundance of cheatgrass, low amounts of soil disturbance and high moss cover. These fires have not resulted in an explosion of the cheatgrass population, perhaps because of the historically low levels of livestock grazing.

  18. Microbial Response to UV Exposure and Nitrogen Limitation in Desert Soil Crusts

    Science.gov (United States)

    Fulton, J. M.; Van Mooy, B. A.

    2016-12-01

    Microbiotic soil crusts have diverse biomarker distributions and C and N stable isotopic compositions that covary with soil type. Sparse plant cover and the relative lack of soil disturbance in arid/semi-arid landscapes allows populations of soil cyanobacteria to develop along with fungi and heterotrophic bacteria. Microbial communities in this extreme environment depend in part on the production of scytonemin, a UV protective pigment, by cyanobacteria near the top of the crust. N limitation of microbial growth also affects soil crust population dynamics, increasing the requirement of N2fixation by diazotrophic cyanobacteria. We collected 56 soil crust samples from 27 locations throughout the Great Salt Lake Desert, including four transects spanning high-elevation, erosion-dominated soils to lower elevation soils dominated by silt-accumulation. Erosion-dominated soil surfaces included rounded gravel and cobbles; in the interstices there were poorly-developed microbiotic crusts on sandy loam with low δ15N values near 0‰ that point toward microbial growth dependent on cyanobacterial N2 fixation. Nutrients regenerated by heterotrophic bacteria may have been eroded from the system, providing a positive feedback for N2 fixation. High scytonemin:chlorophyll a ratios suggest that cyanobacteria required enhanced protection from UV damage in these crusts. A similar increase in scytonemin:chlorophyll a ratio during soil crust rehydration experiments also points toward the importance of UV protection. Glycolipid:phospholipid ratios were lowest where N2 fixation was favored, however, suggesting that the cyanobacterial population was relatively small, possibly because of the metabolic cost of N2fixation. Microbiotic crusts on silt loam soils, on the other hand, had higher δ15N values between 3.5 and 7.8‰, consistent with heterotrophic growth and nutrient recycling. Lower scytonemin:chlorophyll a ratios suggest that relatively high photosynthetic activity was supported in

  19. Efficiency of sulfuric acid, mined gypsum, and two gypsum by-products in soil crusting prevention and sodic soil reclamation

    Energy Technology Data Exchange (ETDEWEB)

    Amezketa, E.; Aragues, R.; Gazol, R. [Gobierno Navarra, Pamplona (Spain). Agricultural Resources Evaluation Center

    2005-06-01

    We evaluated the efficiency of four amendments (sulfuric acid, mined-gypsum, and the by-products coal-gypsum and lacto-gypsum) in crusting prevention of two calcareous nonsodic and sodic soils and in sodic soil reclamation. Treatments for crust prevention consisted of surface-applied amendments at equivalent rates of 5 Mg pure-gypsum ha{sup -1}. Treatments for sodic soil reclamation consisted of surface-applied acid and soil-incorporated gypsums at rates of 1 pure-gypsum requirement. The efficiency of these amendments was evaluated by comparing the final infiltration rates (FIR) of the amended vs. the nonamended soils measured in disturbed-soil columns pounded with low-salinity irrigation water. Electrical conductivity (EC) and Na in the leachates of the sodic soil were measured. In the crusting prevention experiment, FIRs (mm h{sup -1) of the nonsodic soil were 21 (nonamended), 33 to 35 (gypsum materials), and 53 (sulfuric acid), whereas those for the sodic soil were 0 (nonamended), 9 (lacto-gypsum), 15 to 17 (coal- and mined-gypsum), and 21 (sulfuric acid). In the sodic-soil reclamation experiment, FIRs were 0 (nonamended), 8 to 9 (gypsum-materials), and 17 (sulfuric acid) mm h{sup -1}. All amendments were effective in crusting prevention and soil reclamation, but sulfuric acid was the most efficient due to the fastest EC and Na reductions in the leachates. The three gypsum-materials were equally effective in the reclamation process and in the nonsodic soil crusting-prevention, whereas lacto-gypsum was less efficient in the sodic-soil crusting-prevention.

  20. UV-induced effects on growth, photosynthetic performance and sunscreen contents in different populations of the green alga Klebsormidium fluitans (Streptophyta) from alpine soil crusts.

    Science.gov (United States)

    Kitzing, C; Pröschold, T; Karsten, U

    2014-02-01

    Members of the green algal genus Klebsormidium (Klebsormidiales, Streptophyta) are typical components of biological soil crust communities worldwide, which exert important ecological functions. Klebsormidium fluitans (F. Gay) Lokhorst was isolated from an aeroterrestrial biofilm as well as from four different biological soil crusts along an elevational gradient between 600 and 2350 m in the Tyrolean and South Tyrolean Alps (Austria, Italy), which are characterised by seasonally high solar radiation. Since the UVtolerance of Klebsormidium has not been studied in detail, an ecophysiological and biochemical study was applied. The effects of controlled artificial ultraviolet radiation (UVR; sampling location. All data indicate a generally high UV tolerance which surely contributes to the aeroterrestrial lifestyle of K. fluitans in soil crusts of the alpine regions of the European Alps.

  1. Termite- and mulch-mediated rehabilitation of vegetation on crusted soil in West Africa

    NARCIS (Netherlands)

    Mando, A.; Brussaard, L.; Stroosnijder, L.

    1999-01-01

    The rehabilitation of vegetation on structurally crusted soils by triggering termite activity through mulch was studied on three soil types in northern Burkina Faso, West Africa. A split-plot design was used in a fenced environment for the experiment. Insecticide (Dieldrin) was used at a rate of 500

  2. Soil crusting regulator characteristics of some allic humid tropical soils from Colombia

    International Nuclear Information System (INIS)

    Arias, Dora M; Madero E E; Amezquita E

    2001-01-01

    It was collected soil samples within 5 cm of the surface from Amazonia soils in Caqueta (Macagual); Orinoquia in Meta (Carimagua), Casanare (Matazul) and Vichada (La Primavera); and in Andean region in Cauca (San Isidro) and Valle (CIAT, Palmira). In each of those sites, the International Center for Tropical Agriculture (CIAT) has many experiments to know the impact of land husbandry, leguminous associations and rotations and mulches on natural system. After evaluating weighed particle size, sand particle size, soil organic matter, iron, aluminum and silicon oxides, and fertility, it could cluster in three groups according to those characteristics and their importance in governing soil hazard crusting: la Primavera and Carimagua (high organic matter, oxides and fine sand but low in clay); Matazul and Macagual (low in organic matter, oxides and clay but variable sand values); and San Isidro (the greatest in Al 2 O 3 concentrations, high in Fe 2 O 3 clay and fine sand but the poorest in soil organic matter). Soil organic matter contents were significantly associated with the kind of management

  3. Hydrodynamic behaviour of crusted soils in the Sahel: a possible cause for runoff increase?

    Science.gov (United States)

    Malam Abdou, M.; Vandervaere, J.-P.; Bouzou Moussa, I.; Descroix, L.

    2012-04-01

    Crusted soils are in extension in the Sahel. As rainfall has decreased over the past decades (it is now increasing again in the central Sahel) and no significant change was observed in rainfall intensity and in its time and space distribution, it is supposed that land use management is the main cause for crusts cover increase. Fallow shortening, lack of manure, and land overexploitation (wood harvesting, overgrazing) are frequently cited as main factors of soil degradation. Based on field measurements in some small catchments of Western Niger, the hydrodynamics behaviour of the newly crusted soils of this area is described, mostly constituted by erosion crusts. A strong fall in soil saturated conductivity and in the active porosity as well as a rise in bulk density all lead to a quick onset of runoff production. Results are shown from field experiments in sedimentary and basement areas leading to similar conclusions. In both contexts, runoff plot production was measured at the rain event scale from 10-m2 parcels as well as at the catchment outlet. Soil saturated conductivity was reduced by one order of magnitude when crusting occurs, leading to a sharp runoff coefficient increase, from 4% in a weeded millet field and 10% in an old fallow to more than 60% in a erosion-crusted topsoil at the plot scale. At the experimental catchment scale, runoff coefficient has doubled in less than 20 years. In pure Sahelian basins, this resulted in endorheism breaching, and in a widespread river discharge increase. For some right bank tributaries of the Niger River, discharge is three times higher now than before the drought years, in spite of the remaining rainfall deficit. On the other hand, a general increase in flooding hazard frequency is observed in the whole Sahelian stripe. The role of surface crusts in the Sahel is discussed leading to the implementation of new experiments in the future.

  4. Soil stabilization by a prokaryotic desert crust - Implications for Precambrian land biota

    Science.gov (United States)

    Campbell, S. E.

    1979-01-01

    The ecology of the cyanophyte-dominated stromatolitic mat forming the ground cover over desert areas of Utah and Colorado is investigated and implications for the formation of mature Precambrian soils are discussed. The activation of the growth of the two species of filamentous cyanophyte identified and the mobility of their multiple trichromes upon wetting are observed, accompanied by the production and deposition of a sheath capable of accreting and stabilizing sand and clay particles. The formation of calcium carbonate precipitates upon the repeated wetting and drying of desert crust is noted, and it is suggested that the desert crust community may appear in fossil calcrete deposits as lithified microscopic tubes and cellular remains of algal trichromes. The invasion of dry land by both marine and freshwater algae on the model of the desert crust is proposed to be responsible for the accumulation, stabilization and biogenic modification of mature Precambrian soils.

  5. Nitrogen fixation and diurnal changes of photosynthetic activity in Arctic soil crusts at different development stage

    Czech Academy of Sciences Publication Activity Database

    Pushkareva, E.; Kvíderová, Jana; Šimek, Miloslav; Elster, Josef

    2017-01-01

    Roč. 79, 1 March 2017 (2017), s. 21-30 ISSN 1164-5563 Institutional support: RVO:60077344 ; RVO:67985939 Keywords : Soil crust * Arctic * Photosynthetic activity Subject RIV: EH - Ecology, Behaviour; EH - Ecology, Behaviour (BC-A) OBOR OECD: Ecology; Ecology (BC-A) Impact factor: 2.445, year: 2016

  6. Using rainfall simulations to understand the relationship between precipitation, soil crust and infiltration in four agricultural soils

    Science.gov (United States)

    Angulo-Martinez, Marta; Alastrué, Juan; Moret-Fernández, David; Beguería, Santiago; López, Mariví; Navas, Ana

    2017-04-01

    Rainfall simulation experiments were carried out in order to study soil crust formation and its relation with soil infiltration parameters—sorptivity (S) and hydraulic conductivity (K)—on four common agricultural soils with contrasted properties; namely, Cambisol, Gypsisol, Solonchak, and Solonetz. Three different rainfall simulations, replicated three times each of them, were performed over the soils. Prior to rainfall simulations all soils were mechanically tilled with a rototiller to create similar soil surface conditions and homogeneous soils. Rainfall simulation parameters were monitored in real time by a Thies Laser Precipitation Monitor, allowing a complete characterization of simulated rainfall microphysics (drop size and velocity distributions) and integrated variables (accumulated rainfall, intensity and kinetic energy). Once soils dried after the simulations, soil penetration resistance was measured and soil hydraulic parameters, S and K, were estimated using the disc infiltrometry technique. There was little variation in rainfall parameters among simulations. Mean intensity and mean median diameter (D50) varied in simulations 1 ( 0.5 bar), 2 ( 0.8 bar) and 3 ( 1.2 bar) from 26.5 mm h-1 and 0.43 mm (s1) to 40.5 mm h-1 and 0.54 mm (s2) and 41.1 mm h-1 and 0.56 mm for (s3), respectively. Crust formation by soil was explained by D50 and subsequently by the total precipitation amount and the percentage of silt and clay in soil, being Cambisol and Gypsisol the soils that showed more increase in penetration resistance by simulation. All soils showed similar S values by simulations which were explained by rainfall intensity. Different patterns of K were shown by the four soils, which were explained by the combined effect of D50 and intensity, together with soil physico-chemical properties. This study highlights the importance of monitoring all precipitation parameters to determine their effect on different soil processes.

  7. Soil and terrestrial biology studies

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Soil and terrestrial biology studies focused on developing an understanding of the uptake of gaseous substances from the atmosphere by plants, biodegradation of oil, and the movement of Pu in the terrestrial ecosystems of the southeastern United States. Mathematical models were developed for SO 2 and tritium uptake from the atmosphere by plants; the uptake of tritium by soil microorganisms was measured; and the relationships among the Pu content of soil, plants, and animals of the Savannah River Plant area were studied. Preliminary results are reported for studies on the biodegradation of waste oil on soil surfaces

  8. Biologically-initiated rock crust on sandstone: Mechanical and hydraulic properties and resistance to erosion

    Czech Academy of Sciences Publication Activity Database

    Slavík, M.; Bruthans, J.; Filippi, Michal; Schweigstillová, Jana; Falteisek, L.; Řihošek, J.

    2017-01-01

    Roč. 278, FEB 1 (2017), s. 298-313 ISSN 0169-555X R&D Projects: GA ČR GA13-28040S; GA ČR(CZ) GA16-19459S Institutional support: RVO:67985831 ; RVO:67985891 Keywords : biofilm * biocrust * biologically-initiated rock crust * sandstone protection * case hardening Subject RIV: DB - Geology ; Mineralogy; DB - Geology ; Mineralogy (USMH-B) OBOR OECD: Geology; Geology (USMH-B) Impact factor: 2.958, year: 2016

  9. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China.

    Science.gov (United States)

    Wei, Wei; Yu, Yun; Chen, Liding

    2015-01-01

    The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust) to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes.

  10. Soil stabilization by a prokaryotic desert crust: implications for Precambrian land biota.

    Science.gov (United States)

    Campbell, S E

    1979-09-01

    A cyanophyte dominated mat, desert crust, forms the ground cover in areas measuring hundreds of square meters in Utah and smaller patches in Colorado. The algal mat shows stromatolitic features such as sediment trapping and accretion, a convoluted surface, and polygonal cracking. Sand and clay particles are immobilized by a dense network of filaments of the two dominating cyanophyte species, Microcoleus vaginatus and M. chthonoplastes, which secrete sheaths to which particles adhere. These microorganisms can tolerate long periods of desiccation and are capable of instant reactivation and migration following wetting. Migration occurs in two events: 1. immediately following wetting of dry mat, trichomes are mechanically expelled from the sheath as it swells during rehydration, and 2. subsequently, trichomes begin a self-propelled gliding motility which is accompanied by further production of sheath. The maximum distance traveled on solid agar by trichomes of Microcoleus vaginatus during a 12 hour period of light was 4.8 cm. This corresponds to approximately 500 times the length of the fastest trichome, and provides a measure of the potential for spreading of the mat in nature via the motility of the trichomes. Dehydration resistence of the sheath modifies the extracellular environment of the trichomes and enables their transition to dormancy. Following prolonged wetting and evaporative drying of the mat in the laboratory, a smooth wafer-like crust is formed by the sheaths of Microcleus trichomes that have migrated to the surface. Calcium carbonate precipitates among the algal filaments under experimental conditions, indicating a potential for mat lithification and fossilization in the form of a caliche crust. It is suggested that limestones containing tubular microfossils may, in part, be of such an origin. The formation of mature Precambrian soils may be attributable to soil accretion, stabilization, and biogenic modification by blue-green algal land mats similar to

  11. Untangling the biological contributions to soil stability in semiarid shrublands

    Science.gov (United States)

    Chaudhary, V. Bala; Bowker, Matthew A.; O'Dell, Thomas E.; Grace, James B.; Redman, Andrea E.; Rillig, Matthias C.; Johnson, Nancy C.

    2009-01-01

    Communities of plants, biological soil crusts (BSCs), and arbuscular mycorrhizal (AM) fungi are known to influence soil stability individually, but their relative contributions, interactions, and combined effects are not well understood, particularly in arid and semiarid ecosystems. In a landscape-scale field study we quantified plant, BSC, and AM fungal communities at 216 locations along a gradient of soil stability levels in southern Utah, USA. We used multivariate modeling to examine the relative influences of plants, BSCs, and AM fungi on surface and subsurface stability in a semiarid shrubland landscape. Models were found to be congruent with the data and explained 35% of the variation in surface stability and 54% of the variation in subsurface stability. The results support several tentative conclusions. While BSCs, plants, and AM fungi all contribute to surface stability, only plants and AM fungi contribute to subsurface stability. In both surface and subsurface models, the strongest contributions to soil stability are made by biological components of the system. Biological soil crust cover was found to have the strongest direct effect on surface soil stability (0.60; controlling for other factors). Surprisingly, AM fungi appeared to influence surface soil stability (0.37), even though they are not generally considered to exist in the top few millimeters of the soil. In the subsurface model, plant cover appeared to have the strongest direct influence on soil stability (0.42); in both models, results indicate that plant cover influences soil stability both directly (controlling for other factors) and indirectly through influences on other organisms. Soil organic matter was not found to have a direct contribution to surface or subsurface stability in this system. The relative influence of AM fungi on soil stability in these semiarid shrublands was similar to that reported for a mesic tallgrass prairie. Estimates of effects that BSCs, plants, and AM fungi have

  12. Emergence of native plant seeds in response to seed pelleting, planting depth, scarification, and soil anti-crusting treatment, 2009

    Science.gov (United States)

    Clint Shock; Erik Feibert; Lamont Saunders; Nancy Shaw

    2010-01-01

    Seed of native plants is needed to restore rangelands of the Intermountain West. Reliable commercial seed production is desirable to provide the quantity of seed needed for restoration efforts. Establishment of native seed crops has been difficult, because fall-planted seed is susceptible to bird damage, soil crusting, and soil erosion. Fall planting is important for...

  13. The biological and physical role of mulch in the rehabilitation of custed soil in the Sahel

    NARCIS (Netherlands)

    Mando, A.; Stroosnijder, L.

    1999-01-01

    During three consecutive years (1993–1995) a split-plot design with three replications was used to study the biological and physical role of mulch in the improvement of crusted soil water balance and its productivity in the north of Burkina Faso. The main treatment was the use of an insecticide, to

  14. Transient Liquid Water as a Mechanism for Induration of Soil Crusts on Mars

    Science.gov (United States)

    Landis, G. A.; Blaney, D.; Cabrol, N.; Clark, B. C.; Farmer, J.; Grotzinger, J.; Greeley, R.; McLennan, S. M.; Richter, L.; Yen, A.

    2004-01-01

    The Viking and the Mars Exploration Rover missions observed that the surface of Mars is encrusted by a thinly cemented layer tagged as "duricrust". A hypothesis to explain the formation of duricrust on Mars should address not only the potential mechanisms by which these materials become cemented, but also the textural and compositional components of cemented Martian soils. Elemental analyzes at five sites on Mars show that these soils have sulfur content of up to 4%, and chlorine content of up to 1%. This is consistent with the presence of sulfates and halides as mineral cements. . For comparison, the rock "Adirondack" at the MER site, after the exterior layer was removed, had nearly five times lower sulfur and chlorine content , and the Martian meteorites have ten times lower sulfur and chlorine content, showing that the soil is highly enriched in the saltforming elements compared with rock.Here we propose two alternative models to account for the origin of these crusts, each requiring the action of transient liquid water films to mediate adhesion and cementation of grains. Two alternative versions of the transient water hypothesis are offered, a top down hypothesis that emphasizes the surface deposition of frost, melting and downward migration of liquid water and a bottom up alternative that proposes the presence of interstitial ice/brine, with the upward capillary migration of liquid water.

  15. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China.

    Directory of Open Access Journals (Sweden)

    Wei Wei

    Full Text Available The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes.

  16. Response of Surface Soil Hydrology to the Micro-Pattern of Bio-Crust in a Dry-Land Loess Environment, China

    Science.gov (United States)

    Wei, Wei; Yu, Yun; Chen, Liding

    2015-01-01

    The specific bio-species and their spatial patterns play crucial roles in regulating eco-hydrologic process, which is significant for large-scale habitat promotion and vegetation restoration in many dry-land ecosystems. Such effects, however, are not yet fully studied. In this study, 12 micro-plots, each with size of 0.5 m in depth and 1 m in length, were constructed on a gentle grassy hill-slope with a mean gradient of 8° in a semiarid loess hilly area of China. Two major bio-crusts, including mosses and lichens, had been cultivated for two years prior to the field simulation experiments, while physical crusts and non-crusted bare soils were used for comparison. By using rainfall simulation method, four designed micro-patterns (i.e., upper bio-crust and lower bare soil, scattered bio-crust, upper bare soil and lower bio-crust, fully-covered bio-crust) to the soil hydrological response were analyzed. We found that soil surface bio-crusts were more efficient in improving soil structure, water holding capacity and runoff retention particularly at surface 10 cm layers, compared with physical soil crusts and non-crusted bare soils. We re-confirmed that mosses functioned better than lichens, partly due to their higher successional stage and deeper biomass accumulation. Physical crusts were least efficient in water conservation and erosion control, followed by non-crusted bare soils. More importantly, there were marked differences in the efficiency of the different spatial arrangements of bio-crusts in controlling runoff and sediment generation. Fully-covered bio-crust pattern provides the best option for soil loss reduction and runoff retention, while a combination of upper bio-crust and lower bare soil pattern is the least one. These findings are suggested to be significant for surface-cover protection, rainwater infiltration, runoff retention, and erosion control in water-restricted and degraded natural slopes. PMID:26207757

  17. Soil degradation effect on biological activity in Mediterranean calcareous soils

    Science.gov (United States)

    Roca-Pérez, L.; Alcover-Sáez, S.; Mormeneo, S.; Boluda, R.

    2009-04-01

    Soil degradation processes include erosion, organic matter decline, compaction, salinization, landslides, contamination, sealing and biodiversity decline. In the Mediterranean region the climatological and lithological conditions, together with relief on the landscape and anthropological activity are responsible for increasing desertification process. It is therefore considered to be extreme importance to be able to measure soil degradation quantitatively. We studied soil characteristics, microbiological and biochemical parameters in different calcareous soil sequences from Valencia Community (Easter Spain), in an attempt to assess the suitability of the parameters measured to reflect the state of soil degradation and the possibility of using the parameters to assess microbiological decline and soil quality. For this purpose, forest, scrubland and agricultural soil in three soil sequences were sampled in different areas. Several sensors of the soil biochemistry and microbiology related with total organic carbon, microbial biomass carbon, soil respiration, microorganism number and enzyme activities were determined. The results show that, except microorganism number, these parameters are good indicators of a soil biological activity and soil quality. The best enzymatic activities to use like indicators were phosphatases, esterases, amino-peptidases. Thus, the enzymes test can be used as indicators of soil degradation when this degradation is related with organic matter losses. There was a statistically significant difference in cumulative O2 uptake and extracellular enzymes among the soils with different degree of degradation. We would like to thank Spanish government-MICINN for funding and support (MICINN, project CGL2006-09776).

  18. Effects of sand burial and wind disturbances on moss soil crusts in a revegetated area of the Tennger Desert, Northern China

    Science.gov (United States)

    Jia, R. L.; Li, X. R.; Liu, L. C.; Gao, Y. H.

    2012-04-01

    Sand burial and wind are two predominant natural disturbances in the desert ecosystems worldwide. However, the effects of sand burial and wind disturbances on moss soil crusts are still largely unexplored. In this study, two sets of experiments were conducted separately to evaluated the effects of sand burial (sand depth of 0, 1, 2, 3 and 4 mm) and wind blowing (wind speed of 0.2, 3, 6 and 9ms-1) on ecophysiological variables of two moss soil crusts collected from a revegetated area of the Tengger Desert, Northern China. Firstly, the results from the sand burial experiment revealed that respiration rate was significantly decreased and that moss shoot elongation was significantly increased after burial. In addition, Bryum argenteum crust showed the fastest speed of emergence and highest tolerance index, followed by Didymodon vinealis crust. This sequence was consistent with the successional order of the two moss crusts that happened in our study area, indicating that differential sand burial tolerance explains their succession sequence. Secondly, the results from the wind experiment showed that CO2 exchange, PSII photochemical efficiency, photosynthetic pigments, shoot upgrowth, productivity and regeneration potential of the two moss soil crust mentioned above were all substantially depressed. Furthermore, D. vinealis crust exhibited stronger wind resistance than B. argenteum crust from all aspects mentioned above. And this is comparison was identical with their contrasting microhabitats with B. argenteum crust being excluded from higher wind speed microsites in the windward slopes, suggesting that the differential wind resistance of moss soil crusts explains their microdistribution pattern. In conclusion, the ecogeomorphological processes of moss soil crusts in desert ecosystems can be largely determined by natural disturbances caused by sand burial and wind blowing in desert ecosystems.

  19. Distribution and floristics of moss- and lichen-dominated soil crusts in a patterned Callitris glaucophylla woodland in eastern Australia

    Science.gov (United States)

    Eldridge, David J.

    1999-05-01

    The distribution and abundance of soil crust lichens and bryophytes was examined in a patterned Callitris glaucophylla woodland in eastern Australia. Twenty-one lichen species and 26 bryophyte species were collected within thirty quadrats along a sequence of runoff, interception and runoff zones. Crust cover was significantly greatest in the interception zones (79.0 %), followed by the runoff zones (24.0 %), and lowest in the groved, runon zones (6.6 %). Lichens and bryophytes were distributed across all geomorphic zones, and, although there were significantly more moss species in the interception zones (mean = 9.1) compared with either the runoff (4.2) or runon (3.2) zones, the number of lichen species did not vary between zones. Ordination of a reduced data set of 32 species revealed a separation of taxa into distinct groups corresponding to the three geomorphic zones. Canonical correspondence analysis (CCA) of the 32 species and thirteen environmental variables revealed that the most important factors associated with the distribution of species were sheet and scarp erosion, soil stability and coherence, litter cover and crust cover. Surface cracking, microtopography and plant cover were of intermediate importance. The CCA biplot revealed that the timbered runon zones (groves) were dominated by `shade-tolerant' mosses Fissidens vittatus and Barbula hornschuchiana, whilst the heavily eroded runoff zones supported sparse populations of `erosion tolerant' lichens ( Endocarpon rogersii) and mosses (Bryum argenteum and Didymodon torquatus). Interception zones supported a rich suite of `crust forming' mosses and lichens capable of tolerating moderate inundation by overland flow. Two other groups of taxa were identified by this analysis: the `pioneer' group, comprising mainly nitrogen-fixing lichens which occupy the zone of active erosion at the lower edge of the groves, and the `opportunists' dominated by liverworts, occupying the shallow depressions or bays at the

  20. Biological treatment: Soil impacted with crude oil

    International Nuclear Information System (INIS)

    Gilbertson, N.; Severns, J.J.

    1992-01-01

    Biological land treatment proved to be a successful way to manage contamination at a California oil and gas production property. During the project, approximately 120,000 yards of contaminated soil was treated in the treatment plots to below the cleanup goals of 1,000 milligrams per kilograms (mg/kg) total petroleum hydrocarbons. In general, remaining hydrocarbon levels in treated soil were the 200 mg/kg total petroleum hydrocarbons range or lower. Cleanup goals were achieved in less than 2 months for each lift of soil treated. The treated soil was used as fill material in the excavation. No significant odor problems occurred during the project. Groundwater monitoring confirmed that no impact to groundwater occurred due to the biological land treatment process. Design of the treatment plan and regulatory requirements are also discussed

  1. Biological Oxygen Demand in Soils and Litters

    Science.gov (United States)

    Smagin, A. V.; Smagina, M. V.; Sadovnikova, N. B.

    2018-03-01

    Biological oxygen demand (BOD) in mineral and organic horizons of soddy-podzolic soils in the forest-park belt of Moscow as an indicator of their microbial respiration and potential biodestruction function has been studied. The BOD of soil samples has been estimated with a portable electrochemical analyzer after incubation in closed flasks under optimum hydrothermal conditions. A universal gradation scale of this parameter from very low (140 g O2/(m3 h)) has been proposed for mineral and organic horizons of soil. A physically substantiated model has been developed for the vertical distribution of BOD in the soil, which combines the diffusion transport of oxygen from the atmosphere and its biogenic uptake in the soil by the first-order reaction. An analytical solution of the model in the stationary state has been obtained; from it, the soil oxygen diffusivity and the kinetic constants of O2 uptake have been estimated, and the profile-integrated total BOD value has been calculated (0.4-1.8 g O2/(m2 h)), which is theoretically identical to the potential oxygen flux from the soil surface due to soil respiration. All model parameters reflect the recreation load on the soil cover by the decrease in their values against the control.

  2. Soil protists: a fertile frontier in soil biology research.

    Science.gov (United States)

    Geisen, Stefan; Mitchell, Edward A D; Adl, Sina; Bonkowski, Michael; Dunthorn, Micah; Ekelund, Flemming; Fernández, Leonardo D; Jousset, Alexandre; Krashevska, Valentyna; Singer, David; Spiegel, Frederick W; Walochnik, Julia; Lara, Enrique

    2018-05-01

    Protists include all eukaryotes except plants, fungi and animals. They are an essential, yet often forgotten, component of the soil microbiome. Method developments have now furthered our understanding of the real taxonomic and functional diversity of soil protists. They occupy key roles in microbial foodwebs as consumers of bacteria, fungi and other small eukaryotes. As parasites of plants, animals and even of larger protists, they regulate populations and shape communities. Pathogenic forms play a major role in public health issues as human parasites, or act as agricultural pests. Predatory soil protists release nutrients enhancing plant growth. Soil protists are of key importance for our understanding of eukaryotic evolution and microbial biogeography. Soil protists are also useful in applied research as bioindicators of soil quality, as models in ecotoxicology and as potential biofertilizers and biocontrol agents. In this review, we provide an overview of the enormous morphological, taxonomical and functional diversity of soil protists, and discuss current challenges and opportunities in soil protistology. Research in soil biology would clearly benefit from incorporating more protistology alongside the study of bacteria, fungi and animals.

  3. Soil washing and post-wash biological treatment of petroleum hydrocarbon contaminated soils

    OpenAIRE

    Bhandari, Alok

    1992-01-01

    A laboratory scale study was conducted to investigate the treatability of petroleum contaminated soils by soil washing and subsequent biological treatment of the different soil fractions. In addition to soils obtained from contaminated sites, studies were also performed on soils contaminated in the laboratory. Soil washing was performed using a bench-scale soil washing system. Washing was carried out with simultaneous fractionation of the bulk soil into sand, silt and clay fractions. Cl...

  4. Effects of Microbiotic Soil Crust Organisms and Mycorrhizal Fungi on Seedling Growth of Blackbrush (Coleogyne ramosissima)

    National Research Council Canada - National Science Library

    Pendleton, Rosemary

    1999-01-01

    .... A series of experiments conducted from 1993 to 1997 tested the effect of inoculation with arbuscular mycorrhizal fungi on the growth of young blackbrush seedlings under a variety of soil nutrient conditions...

  5. Forest soil biology-timber harvesting relationships: a perspective

    Science.gov (United States)

    M. F. Jurgensen; M. J. Larsen; A. E. Harvey

    1979-01-01

    Timber harvesting has a pronounced effect on the soil microflora by wood removal and changing properties. This paper gives a perspective on soil biology-harvesting relationships with emphasis on the northern Rocky Mountain region. Of special significance to forest management operations are the effects of soil micro-organisms on: the availability of soil nutrients,...

  6. Development of immobilized cyanobacterial amendments for reclamation of microbiotic soil crusts

    Czech Academy of Sciences Publication Activity Database

    Kubečková, Klára; Johansen, J. R.; Warren, S. D.; Sparks, R.

    2003-01-01

    Roč. 148, č. 109 (2003), s. 341-362 ISSN 0342-1120. [Symposium of the International Association for Cyanophyte Research/15./. Barcelona, 03.09.2001-07.09.2001] R&D Projects: GA AV ČR KSK6005114 Keywords : cyanobacteria * cyanobacterial amendments * desert soil Subject RIV: EF - Botanics

  7. Understanding and Enhancing Soil Biological Health: The Solution for Reversing Soil Degradation

    Directory of Open Access Journals (Sweden)

    R. Michael Lehman

    2015-01-01

    Full Text Available Our objective is to provide an optimistic strategy for reversing soil degradation by increasing public and private research efforts to understand the role of soil biology, particularly microbiology, on the health of our world’s soils. We begin by defining soil quality/soil health (which we consider to be interchangeable terms, characterizing healthy soil resources, and relating the significance of soil health to agroecosystems and their functions. We examine how soil biology influences soil health and how biological properties and processes contribute to sustainability of agriculture and ecosystem services. We continue by examining what can be done to manipulate soil biology to: (i increase nutrient availability for production of high yielding, high quality crops; (ii protect crops from pests, pathogens, weeds; and (iii manage other factors limiting production, provision of ecosystem services, and resilience to stresses like droughts. Next we look to the future by asking what needs to be known about soil biology that is not currently recognized or fully understood and how these needs could be addressed using emerging research tools. We conclude, based on our perceptions of how new knowledge regarding soil biology will help make agriculture more sustainable and productive, by recommending research emphases that should receive first priority through enhanced public and private research in order to reverse the trajectory toward global soil degradation.

  8. Photosynthesis of green algal soil crust lichens from arid lands in southern Utah, USA: Role of water content on light and temperature responses of CO2 exchange

    Science.gov (United States)

    Lange, Otto L.; Belnap, Jayne; Meyer, Angelika

    1997-01-01

    Biotic soil crusts are a worldwide phenomenon in arid and semi-arid landscapes. Metabolic activity of the poikilohydric organisms found in these crusts is dominated by quick and drastic changes in moisture availability and long periods of drought. Under controlled conditions, we studied the role of water content on photosynthetic and respiratory CO2 exchange of three green algal soil crust lichens from a desert site in southern Utah (USA): Diploschistes diacapsis (Ach.) Lumbsch, Psora cerebriformis W. Weber, and Squamarina lentigera (Weber) Poelt.Photosynthetic metabolism is activated by extremely small amounts of moisture; lower compensation values for net photosynthesis (NP) are reached between 0.05 and 0.27 mm of precipitation equivalent. Thus, the lichens can use very low degrees of hydration for carbon gain. Maximal NP occurs between 0.39 and 0.94 mm precipitation equivalent, and area-related rates equal 2.6–5.2 μmol CO2 m−2s−1. All three tested species show ‘sun plant’ features, including high light requirements for CO2 exchange compensation and for NP saturation.Diploschistes diacapsis maintains high rates of NP at full water saturation. In contrast, suprasaturated thalli of the other two species show a strong depression in NP which can be removed or reduced by increased external CO2 concentration. Consequently, this depression is most probably caused by increased thallus diffusive resistances due to pathway blockage by water. This depression will greatly limit carbon gain of these species in the field after heavy rain. It occurs at all temperatures of ecological relevance and also under conditions of low light. However, maximum water holding capacity of P. cerebriformis and S. lentigera is higher than that of D. diacapsis. This could mean that periods of hydration favorable for metabolic activity for those two species last longer than those of D. diacapsis. This might compensate for their lower rates of NP during suprasaturation. Thus, two

  9. Remediation of Soil Contaminated with Uranium using a Biological Method

    International Nuclear Information System (INIS)

    Park, Hye Min; Kim, Gye Nam; Shon, Dong Bin; Lee, Ki Won; Chung, Un Soo; Moon, Jai Kwon

    2011-01-01

    Bioremediation is a method to cleanup contaminants in soil or ground water with microorganisms. The biological method can reduce the volume of waste solution and the construction cost and operation cost of soil remediation equipment. Bioremediation can be divided into natural attenuation, bioaugmentation, biostimulation. Biostimulation is technology to improve natural purification by adding nutritional substances, supplying oxygen and controlling pH. In this study, penatron, that is a nutritional substances, was mixed with soil. Optimum conditions for mixing ratios of penatron and soil, and the pH of soil was determined through several bioremediation experiments with soil contaminated with uranium. Also, under optimum experiment conditions, the removal efficiencies of soil and concrete according to reaction time were measured for feasibility analysis of soil and concrete bioremediations

  10. Resistência hidráulica da crosta formada em solos submetidos a chuvas simuladas Crust hydraulic resistance in soils under simulated rain

    Directory of Open Access Journals (Sweden)

    Viviane dos Santos Brandão

    2006-02-01

    Full Text Available Para avaliar a redução da taxa de infiltração em solos sujeitos ao encrostamento decorrente da aplicação de chuvas simuladas, foi realizado um experimento em esquema fatorial 5 x 6, sendo cinco solos (Argissolo Vermelho, Argissolo Vermelho-Amarelo, Latossolo Vermelho-Amarelo, Neossolo Flúvico e Neossolo Quartzarênico e seis energias cinéticas de chuva (0, 525, 1051, 2102, 3153 e 4204 J m-2, com três repetições. A partir dos dados de taxa de infiltração da água no solo e da espessura da crosta, determinadas por micromorfometria, calcularam-se a condutividade e a resistência hidráulica da crosta. Todos os solos apresentaram redução da taxa de infiltração, quando a energia cinética de chuva simulada aplicada aumentou. A resistência hidráulica da crosta aumentou com a energia cinética (especialmente para os solos Argissolos Vermelho-Amarelos e Vermelho até atingir um valor máximo, a partir do qual ocorreu diminuição, atribuída ao desgaste erosivo da crosta provocado pelo aumento do escoamento superficial, associado aos maiores valores de energia cinética da chuva simulada. Por meio de análise de regressão múltipla, foram determinadas a relação da resistência hidráulica da crosta com a energia cinética da chuva e as características químicas e físicas de cada solo. A variável resistência hidráulica da crosta mostrou-se adequada a ser utilizada nos modelos infiltração da água no solo para descrever a influência do encrostamento neste processo.To evaluate the decrease in infiltration rate in crusting soils an experiment was carried out using a rainfall simulator. Treatments were distributed in a factorial schedule 5 x 6, using five soils (Red Ultisol, Red-Yellow Ultisol, Red-Yellow Oxisol, Fluvic Entisol and Arenic Entisol and six rainfall kinetic energies (0, 525, 1051, 2102, 3153, and 4204 J m-2 with three replications. According to the water infiltration rate and crust thickness, as determined by

  11. Soil formation and soil biological properties post mining sites after coal mining in central Europe

    Czech Academy of Sciences Publication Activity Database

    Kaneda, Satoshi; Frouz, Jan; Krištůfek, Václav; Elhottová, Dana; Pižl, Václav; Starý, Josef; Háněl, Ladislav; Tajovský, Karel; Chroňáková, Alica

    2007-01-01

    Roč. 53, - (2007), s. 13 ISSN 0288-5840. [Annual Meeting Japanese Society of Soil Science and Plant Nutrition . 22.08.2007, Setagaya city] Institutional research plan: CEZ:AV0Z60660521 Keywords : soil formation * soil biological properties * post mining sites Subject RIV: EH - Ecology, Behaviour

  12. Biological detoxification of a hydrocarbon contaminated soil

    International Nuclear Information System (INIS)

    Fabbri, F.; Lucchese, G.; Nardella, A.

    2005-01-01

    The soil quality of an industrial site chronically contaminated by 39000 mg/kg of oil was detrimentally affected. Soil treatments by bio-pile and land-farming resulted in a reduction of the level of contamination exceeding 90% of the original values, but without reaching regulatory limits. However, the bio-remediation treatments dramatically reduced the mobility of the contaminants and, accordingly, microbial tests clearly indicate that the soil quality improved to acceptable levels, similar to those typically observed in unaltered soils. Hydrocarbon mobility was estimated by the use of water and mild extractants (methanol and sodium dodecyl sulphate) to leach the contaminants from the soil; soil quality was evaluated by comparing the values of selected microbial and enzymatic parameters of the treated soil samples to reference values determined for natural soils. Microbial assessments included: measurement of the nitrification potential, dehydrogenase activity, measures of respiration and lipase activity, microbial counts (MPN on rich media) and Microtox TM assays of the water elutriate. Dermal absorption potential was evaluated using absorption on C 18 disks

  13. Effects of cropping systems on soil biology

    Science.gov (United States)

    The need for fertilizer use to enhance soil nutrient pools to achieve good crop yield is essential to modern agriculture. Specific management practices, including cover cropping, that increase the activities of soil microorganisms to fix N and mobilize P and micronutrients may reduce annual inputs ...

  14. Actual laser removal of black soiling crust from siliceous sandstone by high pulse repetition rate equipment: effects on surface morphology

    Directory of Open Access Journals (Sweden)

    Iglesias-Campos, M. A.

    2016-03-01

    Full Text Available This research project studies the role of pulse repetition rate in laser removal of black soiling crust from siliceous sandstone, and specifically, how laser fluence correlates with high pulse repetition rates in cleaning practice. The aim is to define practical cleaning processes and determine simple techniques for evaluation based on end-users’ perspective (restorers. Spot and surface tests were made using a Q-switched Nd:YAG laser system with a wide range of pulse repetition rates (5–200 Hz, systematically analysed and compared by macrophotography, portable microscope, stereomicroscope with 3D visualizing and area roughness measurements, SEM imaging and spectrophotometry. The results allow the conclusion that for operation under high pulse repetition rates the average of total energy applied per spot on a treated surface should be attendant upon fluence values in order to provide a systematic and accurate description of an actual laser cleaning intervention.En este trabajo se estudia el papel de la frecuencia de repetición en la limpieza láser de costras de contaminación sobre una arenisca silícea, y concretamente, como se relaciona fluencia y frecuencias elevadas en una limpieza real. Se pretende definir un procedimiento práctico de limpieza y determinar técnicas sencillas de evaluación desde el punto de vista de los usuarios finales (restauradores. Para el estudio se realizaron diferentes ensayos en spot y en superficie mediante un equipo Q-switched Nd:YAG con un amplio rango de frecuencias (5–200 Hz, que se analizaron y compararon sistemáticamente mediante macrofotografía, microscopio portátil, estereomicroscopio con visualización 3D y mediciones de rugosidad en área, imágenes SEM y espectrofotometría. Los resultados permiten proponer que, al trabajar con altas frecuencias, la media de la energía total depositada por spot en la superficie debería acompañar los valores de fluencia para describir y comprender mejor una

  15. Biological Chlorine Cycling in Arctic Peat Soils

    Science.gov (United States)

    Zlamal, J. E.; Raab, T. K.; Lipson, D.

    2014-12-01

    Soils of the Arctic tundra near Barrow, Alaska are waterlogged and anoxic throughout most of the profile due to underlying permafrost. Microbial communities in these soils are adapted for the dominant anaerobic conditions and are capable of a surprising diversity of metabolic pathways. Anaerobic respiration in this environment warrants further study, particularly in the realm of electron cycling involving chlorine, which preliminary data suggest may play an important role in arctic anaerobic soil respiration. For decades, Cl was rarely studied outside of the context of solvent-contaminated sites due to the widely held belief that it is an inert element. However, Cl has increasingly become recognized as a metabolic player in microbial communities and soil cycling processes. Organic chlorinated compounds (Clorg) can be made by various organisms and used metabolically by others, such as serving as electron acceptors for microbes performing organohalide respiration. Sequencing our arctic soil samples has uncovered multiple genera of microorganisms capable of participating in many Cl-cycling processes including organohalide respiration, chlorinated hydrocarbon degradation, and perchlorate reduction. Metagenomic analysis of these soils has revealed genes for key enzymes of Cl-related metabolic processes such as dehalogenases and haloperoxidases, and close matches to genomes of known organohalide respiring microorganisms from the Dehalococcoides, Dechloromonas, Carboxydothermus, and Anaeromyxobacter genera. A TOX-100 Chlorine Analyzer was used to quantify total Cl in arctic soils, and these data were examined further to separate levels of inorganic Cl compounds and Clorg. Levels of Clorg increased with soil organic matter content, although total Cl levels lack this trend. X-ray Absorption Near Edge Structure (XANES) was used to provide information on the structure of Clorg in arctic soils, showing great diversity with Cl bound to both aromatic and alkyl groups

  16. Biological soil crust response to late season prescribed fire in a Great Basin juniper woodland

    Science.gov (United States)

    Steven D. Warren; Larry L. St.Clair; Jeffrey R. Johansen; Paul Kugrens; L. Scott Baggett; Benjamin J. Bird

    2015-01-01

    Expansion of juniper on U.S. rangelands is a significant environmental concern. Prescribed fire is often recommended to control juniper. To that end, a prescribed burn was conducted in a Great Basin juniper woodland. Conditions were suboptimal; fire did not encroach into mid- or late-seral stages and was patchy in the early-seral stage. This study evaluated the effects...

  17. Soil-biological parameters as tools in biomonitoring

    International Nuclear Information System (INIS)

    Kinzel, H.

    1992-01-01

    Soil-biological parameters (enzyme activities, content of metabolites) are sensitive indicators of environmental changes. On the one hand, we tested the possibilities of this method in the vicinity of the trunks of beeches, where most of the pollutants are washed into the soil with the runoff of precipitation water from the tree trunks. On the other hand, we compared soils used for intensive agriculture with more natural soils in the vicinity. In the first of these cases, especially the activities of dehydrogenase and alkaline phosphatase were influenced by atmospheric pollution. In the latter case, a marked effect of agricultural management on the entire soil-biological state was to be noted. The results are derived from investigations by A. Baumgarten, O. Linher, K. Spadinger and S. Zechmeister-Boltenstern. (orig.) [de

  18. Behavior of oxyfluorfen in soils amended with different sources of organic matter. Effects on soil biology.

    Science.gov (United States)

    Gómez, Isidoro; Rodríguez-Morgado, Bruno; Parrado, Juan; García, Carlos; Hernández, Teresa; Tejada, Manuel

    2014-05-30

    We performed a laboratory study on the effect of oxyfluorfen at a rate of 4lha(-1) on biological properties of a soil amended with four organic wastes (two biostimulants/biofertilizers, obtained from rice bran, RB1 and RB2; municipal solid waste, MSW; and sheep manure, SM). Soil was mixed with SM at a rate of 1%, MSW at a rate of 0.52%, RB1 at a rate of 0.39% and RB2 at a rate of 0.30%, in order to apply the same amount of organic matter to the soil. The enzymatic activities and microbial community in the soil were determined during the incubation times. The application of RB1 and RB2 to soil without oxyfluorfen increased the enzymatic activities and biodiversity, peaking at day 10 of the incubation period. This stimulation was higher in the soil amended with RB2 than in that amended with RB1. In SM and CF-amended soils, the stimulation of enzymatic activities and soil biodiversity increased during the experiment. The application of herbicide in organic-amended soils decreased the inhibition of soil enzymatic activities and soil biodiversity. Possibly the low molecular weight protein content easily assimilated by soil microorganisms and the higher fat content in the biostimulants/biofertilizers are responsible for the lower inhibition of these soil biological properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Biological parameters in technogenic soils of a former sulphur mine

    Science.gov (United States)

    Siwik-Ziomek, Anetta; Brzezińska, Małgorzata; Lemanowicz, Joanna; Koper, Jan; Szarlip, Paweł

    2018-04-01

    This study was conducted on the soils originating from a reclamation area of the former sulphur mine in Tarnobrzeg, Poland. Soil was sampled 16 years after the completion of mining works with the open-pit method at Machów, as well as 7 years after sulphur mining via the `smelting' method in the Jeziórko mine was abandoned. Several biological parameters were examined: soil respiration, soil microbial biomass and the activity of rhodanese and arylsulphatase enzymes taking part in sulphur transformation within the site's soils. The soils showed a high total sulphur and sulphates content. The SO42- constituted a large fraction of total sulphur, in some cases, exceeding 80% or even 95% of total sulphur. The soil pH decreased due to the degrading effects of sulphur mining. In the soils studied from the locations with the lowest soil pH value, no activity of arylsulphatase was reported and the activity of rhodanese was lowest. The highest soil respiration values were recorded from the 0-5 cm layer in the areas covered with forest vegetation. A high soil respiration value at the waste heap at Machów wherein a very high concentration of Stot and SO42- was observed can be due to the ability of fungi to produce hyphal strands and to survive unfavourable conditions.

  20. Impact of temperature on the biological properties of soil

    Science.gov (United States)

    Borowik, Agata; Wyszkowska, Jadwiga

    2016-01-01

    The aim of the study was to determine the response of soil microorganisms and enzymes to the temperature of soil. The effect of the temperatures: 5, 10, 15, 20, and 25°C on the biological properties of soil was investigated under laboratory conditions. The study was performed using four different soils differing in their granulometric composition. It was found that 15°C was the optimal temperature for the development of microorganisms in soil. Typically, in the soil, the highest activity of dehydrogenases was observed at 10-15°C, catalase and acid phosphatase - at 15°C, alkaline phosphatase at 20°C, urease and β-glucosidase at 25°C. The highest colony development index for heterotrophic bacteria was recorded in soils incubated at 25°C, while for actinomycetes and fungi at 15°C. The incubation temperature of soil only slightly changed the ecophysiological variety of the investigated groups of microorganisms. Therefore, the observed climate changes might have a limited impact on the soil microbiological activity, because of the high ability of microorganisms to adopt. The response of soil microorganisms and enzymes was more dependent on the soil granulometric composition, organic carbon, and total nitrogen than on its temperature.

  1. Evaluation of Pigeon Pea Lines for Biological Soil Decompaction

    Directory of Open Access Journals (Sweden)

    Rodolfo Godoy

    2009-01-01

    Full Text Available Soil decompaction is generally achieved through mechanical cultivation practices; however biological processes can significantly add to this process through root growth, development, and later senescence. This study was carried out in Piracicaba, SP, Brazil and had the purpose of selecting, among forty one pure pigeon pea lines, the most efficient genotypes that promote soil decompaction by roots penetrating compacted soil layers. Utilizing artificially compacted 30 mm high soil blocks, in a series of experiments, these lines were compared to the cultivar Fava Larga taken as a standard. Three lines were preliminarily selected out of the initial group, and afterwards, in more detailed screenings by monitoring soil resistance to penetration and also evaluating the behavior of Tanzania grass plants seeded after pigeon pea, two of them, g5-94 and g8-95, were selected as possessing the most fit root system to penetrate compacted soil layers.

  2. Proceedings of the California Forest Soils Council Conference on Forest Soils Biology and Forest Management

    Science.gov (United States)

    Robert F. Powers; Donald L. Hauxwell; Gary M. Nakamura

    2000-01-01

    Biotic properties of forest soil are the linkages connecting forest vegetation with an inert rooting medium to create a dynamic, functioning ecosystem. But despite the significance of these properties, managers have little awareness of the biotic world beneath their feet. Much of our working knowledge of soil biology seems anchored in myth and misunderstanding. To...

  3. Soil biological activity as affected by tillage intensity

    Science.gov (United States)

    Gajda, A. M.; Przewłoka, B.

    2012-02-01

    The effect of tillage intensity on changes of microbiological activity and content of particulate organic matter in soil under winter wheat duirng 3 years was studied. Microbial response related to the tillage-induced changes in soil determined on the content of biomass C and N, the rate of CO2 evolution, B/F ratio, the activity of dehydrogenases, acid and alkaline phosphatases, soil C/N ratio and microbial biomass C/N ratio confirmed the high sensitivity of soil microbial populations to the tillage system applied. After three year studies, the direct sowing system enhanced the increase of labile fraction of organic matter content in soil. There were no significant changes in the labile fraction quantity observed in soil under conventional tillage. Similar response related to the tillage intensity was observed in particulate organic matter quantities expressed as a percentage of total organic matter in soil. A high correlation coefficients calculated between contents of soil microbial biomass C and N, particulate organic matter and potentially mineralizable N, and the obtained yields of winter wheat grown on experimental fields indicated on a high importance of biological quality of status of soil for agricultural crop production.

  4. Biological activity of soils strongly polluted with sulfur

    Energy Technology Data Exchange (ETDEWEB)

    Krol, M; Maliszewska, W; Siuta, J

    1972-01-01

    Studies were carried out on soils strongly polluted with sulfur and acidified (to pH 1.4). The soils were subjected to an intensive liming. In field and pot experiments, the authors determined: the total quantity of bacteria, actinomycetes, fungi, azotobacter, nitrifiers, proteolytic activity of microorganisms, activity of ammonifiers and the number of sulfur-oxidizing and sulfate-reducing bacteria. It was found that intensive liming of sulfur-affected soils restored their biological activity. 8 references, 5 figures, 1 table.

  5. Biological decomposition of aqueous solutions from soil cleaning

    International Nuclear Information System (INIS)

    Kniebusch, M.M.; Sekoulov, I.

    1993-01-01

    The biological cleaning of process water from soil cleaning and from contaminated groundwater required the development of new types of reaction systems. With the introduced membrane biofilm reactor, even substances difficult to decompose can be removed from contaminated water. Previous investigations of the elimination of pyrene in the presence of n-hexadecane show an optimum temperature at 30 C. An increase of scale is possible based on the invesstigations carried out on the aerobic biological decomposition of polycyclic aromatic hydrocarbons. (orig.) [de

  6. Dryland soil microbial communities display spatial biogeographic patterns associated with soil depth and soil parent material

    Science.gov (United States)

    Steven, Blaire; Gallegos-Graves, La Verne; Belnap, Jayne; Kuske, Cheryl R.

    2013-01-01

    Biological soil crusts (biocrusts) are common to drylands worldwide. We employed replicated, spatially nested sampling and 16S rRNA gene sequencing to describe the soil microbial communities in three soils derived from different parent material (sandstone, shale, and gypsum). For each soil type, two depths (biocrusts, 0–1 cm; below-crust soils, 2–5 cm) and two horizontal spatial scales (15 cm and 5 m) were sampled. In all three soils, Cyanobacteria and Proteobacteria demonstrated significantly higher relative abundance in the biocrusts, while Chloroflexi and Archaea were significantly enriched in the below-crust soils. Biomass and diversity of the communities in biocrusts or below-crust soils did not differ with soil type. However, biocrusts on gypsum soil harbored significantly larger populations of Actinobacteria and Proteobacteria and lower populations of Cyanobacteria. Numerically dominant operational taxonomic units (OTU; 97% sequence identity) in the biocrusts were conserved across the soil types, whereas two dominant OTUs in the below-crust sand and shale soils were not identified in the gypsum soil. The uniformity with which small-scale vertical community differences are maintained across larger horizontal spatial scales and soil types is a feature of dryland ecosystems that should be considered when designing management plans and determining the response of biocrusts to environmental disturbances.

  7. Biological indices of soil quality: an ecosystem case study of their use

    Science.gov (United States)

    Jennifer D. Knoepp; David C. Coleman; D.A. Crossley; James S. Clark

    2000-01-01

    Soil quality indices can help ensure that site productivity and soil function are maintained. Biological indices yield evidence of how a soil functions and interacts with the plants, animals, and climate that comprise an ecosystem. Soil scientists can identify and quantify both chemical and biological soil-quality indicators for ecosystems with a single main function,...

  8. Biological and biochemical soil quality indicators for agricultural management

    Science.gov (United States)

    Bongiorno, Giulia

    2017-04-01

    Soil quality is defined as the capacity of a soil to perform multiple functions. Agricultural soils can, in principle, sustain a wide range of functions. However, negative pressure exerted by natural and anthropogenic soil threats such as soil erosion, soil organic matter losses and soil compaction have the potential to permanently damage soil quality. Soil chemical, physical and biological parameters can be used as indicators of soil quality. The specific objective of this study is to assess the suitability of novel soil parameters as soil quality indicators. We focus on biological/biochemical parameters, due to the unique role of soil biota in soil functions and to their high sensitivity to disturbances. The novel indicators are assessed in ten European long-term field experiments (LTEs) with different agricultural land use (arable and permanent crops), management regimes and pedo-climatic characteristics. The contrasts in agricultural management are represented by conventional/reduced tillage, organic/mineral fertilization and organic matter addition/no organic matter addition. We measured two different pools of labile organic carbon (dissolved organic carbon (DOC), and permanganate oxidizable carbon (POXC)), and determined DOC quality through its fractionation in hydrophobic and hydrophilic compounds. In addition, total nematode abundance has been assessed with qPCR. These parameters will be related to soil functions which have been measured with a minimum data set of indicators for soil quality (including TOC, macronutrients, and soil respiration). As a preliminary analysis, the Sensitivity Index (SI) for a given LTE was calculated for DOC and POXC according to Bolinder et al., 1999 as the ratio of the soil attribute under modified practices (e.g. reduced tillage) compared to the conventional practices (e.g. conventional tillage). The overall effect of the sustainable management on the indicators has been derived by calculating an average SI for those LTEs

  9. Some physico-chemical and biological characteristics of soil and ...

    African Journals Online (AJOL)

    Environmental conditions that influence biocorrosion in the Niger Delta area of Nigeria are investigated experimentally by analysing the physico-chemical and biological characteristics of four (4) soil samples and water samples taken from ten (10) selected river bodies in the region. Measured properties of the water ...

  10. Vegetation improvement and soil biological quality in the Sahel of ...

    African Journals Online (AJOL)

    The method of Tropical Soil Biology and Fertility (TSBF) was used to assess macro-fauna abundance and diversity in different land use types (cropland, shallow land, degraded land and forest). Four sites were selected, in the Sahelian zone of Burkina Faso, with contrasted Normalized Difference Vegetation Index (NDVI).

  11. Biological technologies for the remediation of co-contaminated soil.

    Science.gov (United States)

    Ye, Shujing; Zeng, Guangming; Wu, Haipeng; Zhang, Chang; Dai, Juan; Liang, Jie; Yu, Jiangfang; Ren, Xiaoya; Yi, Huan; Cheng, Min; Zhang, Chen

    2017-12-01

    Compound contamination in soil, caused by unreasonable waste disposal, has attracted increasing attention on a global scale, particularly since multiple heavy metals and/or organic pollutants are entering natural ecosystem through human activities, causing an enormous threat. The remediation of co-contaminated soil is more complicated and difficult than that of single contamination, due to the disparate remediation pathways utilized for different types of pollutants. Several modern remediation technologies have been developed for the treatment of co-contaminated soil. Biological remediation technologies, as the eco-friendly methods, have received widespread concern due to soil improvement besides remediation. This review summarizes the application of biological technologies, which contains microbial technologies (function microbial remediation and composting or compost addition), biochar, phytoremediation technologies, genetic engineering technologies and biochemical technologies, for the remediation of co-contaminated soil with heavy metals and organic pollutants. Mechanisms of these technologies and their remediation efficiencies are also reviewed. Based on this study, this review also identifies the future research required in this field.

  12. Application of the biological forced air soil treatment (BIOFAST trademark) technology to diesel contaminated soil

    International Nuclear Information System (INIS)

    Lyons, K.A.; Leavitt, M.E.; Graves, D.A.; Stanish, S.M.

    1993-01-01

    A subsurface Biological Forced Air Soil Treatment (BIOFAST trademark) system was constructed at the Yellow Freight System, Inc. (Yellow Freight) New Haven facility in Connecticut as a means of expediting the remediation of soils impacted by a diesel fuel release. Prior to beginning construction activities the soils were evaluated for the feasibility of bioremediation based on soil characteristics including contaminant degrading bacteria, moisture content, and pH. Based on results of stimulant tests with oxygen and nutrients, the addition of fertilizer during the construction of the cell was recommended. Following the removal of underground storage tanks, the bioremediation cell was constructed by lining the enlarged excavation with high density polyethylene (HDPE) and backfilling alternating layers of nutrient-laden soil and pea gravel. Passive and active soil vapor extraction (SVE) piping was included in the gravel layers and connected to a blower and vapor treatment unit, operated intermittently to supply oxygen to the subsurface cell. Operating data have indicated that the bacteria are generating elevated levels of CO 2 , and the SVE unit is evacuating the accumulated CO 2 from the soils and replacing it with fresh air. These data suggest that the bioremediation process is active in the soils. Soil samples collected from within the soil pit subsequent to installation and again after 10 months of operation indicate that TPH concentrations have decreased by as much as 50%

  13. Biological activity of soil contaminated with cobalt, tin, and molybdenum.

    Science.gov (United States)

    Zaborowska, Magdalena; Kucharski, Jan; Wyszkowska, Jadwiga

    2016-07-01

    In this age of intensive industrialization and urbanization, mankind's highest concern should be to analyze the effect of all metals accumulating in the environment, both those considered toxic and trace elements. With this aim in mind, a unique study was conducted to determine the potentially negative impact of Sn(2+), Co(2+), and Mo(5+) in optimal and increased doses on soil biological properties. These metals were applied in the form of aqueous solutions of Sn(2+) (SnCl2 (.)2H2O), Co(2+) (CoCl2 · 6H2O), and Mo(5+) (MoCl5), each in the doses of 0, 25, 50, 100, 200, 400, and 800 mg kg(-1) soil DM. The activity of dehydrogenases, urease, acid phosphatase, alkaline phosphatase, arylsulfatase, and catalase and the counts of twelve microorganism groups were determined on the 25th and 50th day of experiment duration. Moreover, to present the studied problem comprehensively, changes in the biochemical activity and yield of spring barley were shown using soil and plant resistance indices-RS. The study shows that Sn(2+), Co(2+), and Mo(5+) disturb the state of soil homeostasis. Co(2+) and Mo(5+) proved the greatest soil biological activity inhibitors. The residence of these metals in soil, particularly Co(2+), also generated a drastic decrease in the value of spring barley resistance. Only Sn(2+) did not disrupt its yielding. The studied enzymes can be arranged as follows for their sensitivity to Sn(2+), Co(2+), Mo(5+): Deh > Ure > Aryl > Pal > Pac > Cat. Dehydrogenases and urease may be reliable soil health indicators.

  14. Biological soil disinfestation : a safe and effective approach for controlling soilborne pests and diseases

    NARCIS (Netherlands)

    Lamers, J.G.; Wanten, P.J.; Blok, W.J.

    2004-01-01

    Biological soil disinfestation (bsd) is an environmentally friendly method to disinfest the soil from soilborne fungi and nematodes. With biological soil disinfestation a green manure crop (40 tonnes per ha) or other green biomass is homogeneously incorporated into the soil layer that has to be

  15. Evaluating anaerobic soil disinfestation and other biological soil management methods for open-field tomato production in Florida

    Science.gov (United States)

    Anaerobic soil disinfestation (ASD), amending the soil with composted poultry litter (CPL) and molasses (M), has been shown to be a potential alternative to chemical soil fumigation for tomato production, however, optimization of ASD and the use of other biologically-based soil management practices ...

  16. Crop production in salt affected soils: A biological approach

    Energy Technology Data Exchange (ETDEWEB)

    Malik, K A [National Inst. for Biotechnology and Genetic Engineering (NIBGE), Faisalabad (Pakistan)

    1995-01-01

    Plant are susceptible to various stresses, affecting growth productivity. Among the abiotic stresses, soil salinity is most significant and prevalent in both developed and developing countries. As a result, good productive lands are being desertified at a very high pace. To combat this problem various approaches involving soil management and drainage are underway but with little success. It seems that a durable solution of the salinity and water-logging problems may take a long time and we may have to learn to live with salinity and to find other ways to utilize the affected lands fruitfully. A possible approach could be to tailor plants to suit the deleterious environment. The saline-sodic soils have excess of sodium, are impermeable, have little or no organic matter and are biologically almost dead. Introduction of a salt tolerant crop will provide a green cover and will improve the environment for biological activity, increase organic matter and will improve the soil fertility. The plant growth will result in higher carbon dioxide levels, and would thus create acidic conditions in the soil which would dissolve the insoluble calcium carbonate and will help exchange sodium with calcium ions on the soil complex. The biomass produced could be used directly as fodder or by the use of biotechnological and other procedures it could be converted into other value added products. However, in order to tailor plants to suit these deleterious environments, acquisition of better understanding of the biochemical and genetic aspects of salt tolerance at the cellular/molecular level is essential. For this purpose model systems have been carefully selected to carry out fundamental basic research that elucidates and identifies the major factors that confer salt tolerance in a living system. With the development of modern biotechnological methods it is now possible to introduce any foreign genetic material known to confer salt tolerance into crop plants. (Abstract Truncated)

  17. Role of soil biology and soil functions in relation to land use intensity.

    Science.gov (United States)

    Bondi, Giulia; Wall, David; Bacher, Matthias; Emmet-Booth, Jeremy; Graça, Jessica; Marongiu, Irene; Creamer, Rachel

    2017-04-01

    The delivery of the ecosystem's functions is predominantly controlled by soil biology. The biology found in a gram of soil contains more than ten thousand individual species of bacteria and fungi (Torsvik et al., 1990). Understanding the role and the requirements of these organisms is essential for the protection and the sustainable use of soils. Soil biology represents the engine of all the processes occurring in the soil and it supports the ecosystem services such as: 1) nutrient mineralisation 2) plant production 3) water purification and regulation and 4) carbon cycling and storage. During the last years land management type and intensity have been identified as major drivers for microbial performance in soil. For this reason land management needs to be appropriately studied to understand the role of soil biology within this complex interplay of functions. We aimed to study whether and how land management drives soil biological processes and related functions. To reach this objective we built a land use intensity index (LUI) able to quantify the impact of the common farming practices carried out in Irish grassland soils. The LUI is derived from a detailed farmer questionnaire on grassland management practices at 38 farms distributed in the five major agro-climatic regions of Ireland defined by Holden and Brereton (2004). Soils were classified based on their drainage status according to the Irish Soil Information System by Creamer et al. (2014). This detailed questionnaire is then summarised into 3 management intensity components: (i) intensity of Fertilisation (Fi), (ii) frequency of Mowing (Mi) and (iii) intensity of Livestock Grazing (Gi). Sites were sampled to assess the impact of land management intensity on microbial community structure and enzyme behaviour in relation to nitrogen, phosphorus and carbon cycling. Preliminary results for enzymes linked to C and N cycles showed higher activity in relation to low grazing pressure (low Gi). Enzymes linked to P

  18. Effect of mineralogical, geochemical and biological properties on soils reflectance to assess temporal and spatial dynamics of BSCs in Sahelian ecosystems

    Science.gov (United States)

    Bourguignon, A.; Cerdan, O.; Desprats, J. F.; Marin, B.; Malam Issa, O.; Valentin, C.; Rajot, J. L.

    2012-04-01

    Land degradation and desertification are among the major environmental problems, resulting in reduced productivity and development of bare surfaces in arid and semi-arid areas of the world. One important factor that acts to increase soil stability and nutrient content, and thus to prevent water and wind erosion and enhance soil productivity of arid environment, is the presence of biological soil crusts (BSCs). They are the dominant ground cover and a key component of arid environments built up mainly by cyanobacteria. They enhance degraded soil quality by providing a stable and water-retaining substratum and increasing fertility by N and C fixations. The BioCrust project, funded by ANR (VMCS 2008), focuses on BSCs in the Sahelian zone of West Africa (Niger), a highly vulnerable zone facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use. Unlike arid areas of developed countries (USA, Australia and Israel) or China where BSCs have been extensively studied, studies from Sahelian zone (Africa) are limited (neither the inventory of their different form nor the estimation of their spatial extension has been carried out). The form, structure and composition of BSCs vary depending on characteristics related to soils and biological composition. This study focuses on the soils characterisation using ground-based spectroradiometry. An extensive database was built included spectral measurements on BSCs, bare soils and vegetation that occur in the same area, visual criteria, in situ and laboratory measurements on the physical, chemical and biological characteristics of BSCs and their substratum. The work is carried out on geo-statistical processing of data acquired in sites along a north-south climatic gradient and three types of representative land uses. The investigated areas are highly vulnerable zone facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic

  19. Biologically induced formation of realgar deposits in soil

    Science.gov (United States)

    Drahota, Petr; Mikutta, Christian; Falteisek, Lukáš; Duchoslav, Vojtěch; Klementová, Mariana

    2017-12-01

    The formation of realgar (As4S4) has recently been identified as a prominent As sequestration pathway in the naturally As-enriched wetland soil at the Mokrsko geochemical anomaly (Czech Republic). Here we used bulk soil and pore water analyses, synchrotron X-ray absorption spectroscopy, S isotopes, and DNA extractions to determine the distribution and speciation of As as a function of soil depth and metabolic properties of microbial communities in wetland soil profiles. Total solid-phase analyses showed that As was strongly correlated with organic matter, caused by a considerable As accumulation (up to 21 g kg-1) in an organic-rich soil horizon artificially buried in 1980 at a depth of ∼80 cm. Extended X-ray absorption fine structure spectroscopy revealed that As in the buried organic horizon was predominantly present as realgar occurring as nanocrystallites (50-100 nm) in millimeter-scale deposits associated with particulate organic matter. The realgar was depleted in the 34S isotope by 9-12.5‰ relative to the aqueous sulfate supplied to the soil, implying its biologically induced formation. Analysis of the microbial communities by 16S rDNA sequencing showed that realgar deposits formed in strictly anaerobic organic-rich domains dominated by sulfate-reducing and fermenting metabolisms. In contrast, realgar deposits were not observed in similar domains with even small contributions of oxidative metabolisms. No association of realgar with specific microbial species was observed. Our investigation shows that strongly reducing microenvironments associated with buried organic matter are significant biogeochemical traps for As, with an estimated As accumulation rate of 61 g As m-2 yr-1. Nevertheless the production of biologically induced realgar in these microenvironments is too slow to lower As groundwater concentrations at our field site (∼6790 mg L-1). Our study demonstrates the intricate link between geochemistry and microbial community dynamics in wetland

  20. Large-scale experience with biological treatment of contaminated soil

    International Nuclear Information System (INIS)

    Schulz-Berendt, V.; Poetzsch, E.

    1995-01-01

    The efficiency of biological methods for the cleanup of soil contaminated with total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH) was demonstrated by a large-scale example in which 38,000 tons of TPH- and PAH-polluted soil was treated onsite with the TERRAFERM reg-sign degradation system to reach the target values of 300 mg/kg TPH and 5 mg/kg PAH. Detection of the ecotoxicological potential (Microtox reg-sign assay) showed a significant decrease during the remediation. Low concentrations of PAH in the ground were treated by an in situ technology. The in situ treatment was combined with mechanical measures (slurry wall) to prevent the contamination from dispersing from the site

  1. Integrating soil physical and biological properties in contrasting tillage systems in organic and conventional farming

    NARCIS (Netherlands)

    Crittenden, S.J.; Goede, de R.G.M.

    2016-01-01

    Though soil physical and soil biological properties are intrinsically linked in the soil environment they are often studied separately. This work adds value to analyses of soil biophysical quality of tillage systems under organic and conventional farming systems by correlating physical and

  2. Soil Physical Characteristics and Biological Indicators of Soil Quality Under Different Biodegradable Mulches

    Science.gov (United States)

    Schaeffer, S. M.; Flury, M.; Sintim, H.; Bandopadhyay, S.; Ghimire, S.; Bary, A.; DeBruyn, J.

    2015-12-01

    Application of conventional polyethylene (PE) mulch in crop production offers benefits of increased water use efficiency, weed control, management of certain plant diseases, and maintenance of a micro-climate conducive for plant growth. These factors improve crop yield and quality, but PE must be retrieved and safely disposed of after usage. Substituting PE with biodegradable plastic mulches (BDM) would alleviate disposal needs, and is potentially a more sustainable practice. However, knowledge of potential impacts of BDMs on agricultural soil ecosystems is needed to evaluate sustainability. We (a) monitored soil moisture and temperature dynamics, and (b) assessed soil quality upon usage of different mulches, with pie pumpkin (Cucurbita pepo) as the test crop. Experimental field trials are ongoing at two sites, one at Northwestern Washington Research and Extension Center, Mount Vernon, WA, and the other at East Tennessee Research and Education Center, Knoxville, TN. The treatments constitute four different commercial BDM products, one experimental BDM; no mulch and PE served as the controls. Soil quality parameters being examined include: organic matter content, aggregate stability, water infiltration rate, CO2 flux, pH, and extracellular enzyme activity. In addition, lysimeters were installed to examine the soil water and heat flow dynamics. We present baseline and the first field season results from this study. Mulch cover appeared to moderate soil temperatures, but biodegradable mulches also appeared to lose water more quickly than PE. All mulch types, with the exception of cellulose, reduced the diurnal fluctuations in soil temperature at 10cm depth from 1 to 4ºC. However, volumetric water content ranged from 0.10 to 0.22 m3 m-3 under the five biodegradable mulches compared to 0.22 to 0.28 m3 m-3 under conventional PE. Results from the study will be useful for management practices by providing knowledge on how different mulches impact soil physical and

  3. Soil texture and climatc conditions for biocrust growth limitation: a meta analysis

    Science.gov (United States)

    Fischer, Thomas; Subbotina, Mariia

    2015-04-01

    Along with afforestation, attempts have been made to combat desertification by managing soil crusts, and is has been reported that recovery rates of biocrusts are dependent on many factors, including the type, severity, and extent of disturbance; structure of the vascular plant community; conditions of adjoining substrates; availability of inoculation material; and climate during and after disturbance (Belnap & Eldridge 2001). Because biological soil crusts are known to be more stable on and to prefer fine substrates (Belnap 2001), the question arises as to how successful crust management practices can be applied to coarser soil. In previous studies we observed similar crust biomasses on finer soils under arid and on coarser soils under temperate conditions. We hypothesized that the higher water holding capacity of finer substrates would favor crust development, and that the amount of silt and clay in the substrate that is required for enhanced crust development would vary with changes in climatic conditions. In a global meta study, climatic and soil texture threshold values promoting BSC growth were derived. While examining literature sources, it became evident that the amount of studies to be incorporated into this meta analysis was reversely related to the amount of common environmental parameters they share. We selected annual mean precipitaion, mean temperature and the amount of silt and clay as driving variables for crust growth. Response variable was the "relative crust biomass", which was computed per literature source as the ratio between each individual crust biomass value of the given study to the study maximum value reported. We distinguished lichen, green algal, cyanobacterial and moss crusts. To quantify threshold conditions at which crust biomass responded to differences in texture and climate, we (I) determined correlations between bioclimatic variables, (II) calculated linear models to determine the effect of typical climatic variables with soil

  4. Cyanobacterial crust induction using two non-previously tested cyanobacterial inoculants: crusting capability and role of EPSs

    Science.gov (United States)

    Mugnai, Gianmarco; Rossi, Federico; De Philippis, Roberto

    2017-04-01

    The use of cyanobacteria as soil improvers and bio-conditioners (a technique often referred to as algalization) has been studied for decades. Several studies proved that cyanobacteria are feasible eco-friendly candidates to trigger soil fertilization and enrichment from agricultural to arid and hyper-arid systems. This approach can be successful to achieve stabilization and rehabilitation of degraded environments. Much of the effectiveness of algalization is due to the productivity and the characteristics of extracellular polysaccharides (EPSs) which, among their features, embed soil particles and promote the development of a first stable organo-mineral layer (cyanobacterial crusts). In natural settings, cyanobacterial crust induction represents a first step of a succession that may lead to the formation of mature biological soil crusts (Lan et al., 2014). The aim of this research was to investigate the crusting capabilities, and the characteristics of excreted EPSs by two newly tested non-heterocystous cyanobacterial inoculants, in microcosm experiments carried out using oligothrophic sand collected from sand dunes in Negev Desert, Israel. The cyanobacteria tested were Schizothrix AMPL1601, originally isolated from biocrusts collected in Hobq Desert, Inner Mongolia (China) and Leptolyngbia ohadii, originally isolated from biocrusts collected in Negev Desert, Israel. Inoculated microcosms were maintained at 30 °C in a growth chamber under continuous illumination and minimal water availability. Under such stressing conditions, and for a three-months incubation time, the growth and the colonization of the strains in the microcosms were monitored. At the same time, EPSs production and their chemical and macromolecular characteristics were determined by applying a methodology optimized for the purpose. Notably, EPSs were analyzed in two operationally-defined fractions, one more dispersed in the crust matrix (loosely bound EPSs, LB-EPSs) and one more condensed and

  5. Rapid development of cyanobacterial crust in the field for combating desertification.

    Science.gov (United States)

    Park, Chan-Ho; Li, Xin Rong; Zhao, Yang; Jia, Rong Liang; Hur, Jae-Seoun

    2017-01-01

    Desertification is currently a major concern, and vast regions have already been devastated in the arid zones of many countries. Combined application of cyanobacteria with soil fixing chemicals is a novel method of restoring desertified areas. Three cyanobacteria, Nostoc sp. Vaucher ex Bornet & Flahault, Phormidium sp. Kützing ex Gomont and Scytonema arcangeli Bornet ex Flahault were isolated and tested in this study. Tacki-SprayTM (TKS7), which consists of bio-polysaccharides and tackifiers, was used as a soil fixing agent. In addition, superabsorbent polymer (SAP) was applied to the soil as a water-holding material and nutrient supplement. Application of cyanobacteria with superabsorbent polymer and TKS7 (CST) remarkably improved macro-aggregate stability against water and erodibility against wind after 12 months of inoculation when compared to the control soil. The mean weight diameter and threshold friction velocity of the CST treated soil were found to be 75% and 88% of those of the approximately 20-year-old natural cyanobacterial crust (N-BSC), respectively, while these values were 68% and 73% of those of the N-BSC soil after a single treatment of cyanobacteria alone (CY). Interestingly, biological activities of CST were similar to those of CY. Total carbohydrate contents, cyanobacterial biomass, microbial biomass, soil respiration, carbon fixation and effective quantum yield of CST treated soil were enhanced by 50-100% of the N-BSC, while those of control soil were negligible. Our results suggest that combined application of cyanobacteria with soil fixing chemicals can rapidly develop cyanobacterial crust formation in the field within 12 months. The physical properties and biological activities of the inoculated cyanobacterial crust were stable during the study period. The novel method presented herein serves as another approach for combating desertification in arid regions.

  6. Rapid development of cyanobacterial crust in the field for combating desertification.

    Directory of Open Access Journals (Sweden)

    Chan-Ho Park

    Full Text Available Desertification is currently a major concern, and vast regions have already been devastated in the arid zones of many countries. Combined application of cyanobacteria with soil fixing chemicals is a novel method of restoring desertified areas. Three cyanobacteria, Nostoc sp. Vaucher ex Bornet & Flahault, Phormidium sp. Kützing ex Gomont and Scytonema arcangeli Bornet ex Flahault were isolated and tested in this study. Tacki-SprayTM (TKS7, which consists of bio-polysaccharides and tackifiers, was used as a soil fixing agent. In addition, superabsorbent polymer (SAP was applied to the soil as a water-holding material and nutrient supplement. Application of cyanobacteria with superabsorbent polymer and TKS7 (CST remarkably improved macro-aggregate stability against water and erodibility against wind after 12 months of inoculation when compared to the control soil. The mean weight diameter and threshold friction velocity of the CST treated soil were found to be 75% and 88% of those of the approximately 20-year-old natural cyanobacterial crust (N-BSC, respectively, while these values were 68% and 73% of those of the N-BSC soil after a single treatment of cyanobacteria alone (CY. Interestingly, biological activities of CST were similar to those of CY. Total carbohydrate contents, cyanobacterial biomass, microbial biomass, soil respiration, carbon fixation and effective quantum yield of CST treated soil were enhanced by 50-100% of the N-BSC, while those of control soil were negligible. Our results suggest that combined application of cyanobacteria with soil fixing chemicals can rapidly develop cyanobacterial crust formation in the field within 12 months. The physical properties and biological activities of the inoculated cyanobacterial crust were stable during the study period. The novel method presented herein serves as another approach for combating desertification in arid regions.

  7. Calorimetric studies of cryptogamic crust metabolism in response to temperature, water vapor, and liquid water

    Science.gov (United States)

    Dorothy A. Stradling; Tonya Thygerson; Bruce N. Smith; Lee D. Hansen; Richard S. Criddle; Rosemary L. Pendleton

    2001-01-01

    Cryptogamic crusts are communities composed of lichens, cyanobacteria, algae, mosses, and fungi. These integrated soil crusts are susceptible to disturbance, but if intact, appear to play a role in providing nutrients, especially nitrogen, to higher plants. It is not known how or under what conditions desert crusts can grow. Crust samples from localities on the...

  8. Effects of organic versus conventional management on chemical and biological parameters in agricultural soils

    NARCIS (Netherlands)

    Diepeningen, van A.D.; Vos, de O.J.; Korthals, G.W.; Bruggen, van A.H.C.

    2006-01-01

    A comparative study of organic and conventional arable farming systems was conducted in The Netherlands to determine the effect of management practices on chemical and biological soil properties and soil health. Soils from thirteen accredited organic farms and conventionally managed neighboring

  9. Biological Activity Assessment in Mexican Tropical Soils with Different Hydrocarbon Contamination Histories

    OpenAIRE

    Riveroll-Larios, Jessica; Escalante-Espinosa, Erika; Fócil-Monterrubio, Reyna L.; Díaz-Ramírez, Ildefonso J.

    2015-01-01

    The use of soil health indicators linked to microbial activities, such as key enzymes and respirometric profiles, helps assess the natural attenuation potential of soils contaminated with hydrocarbons. In this study, the intrinsic physicochemical characteristics, biological activity and biodegradation potential were recorded for two soils with different contamination histories (>5 years and

  10. The characterization of the soil biological quality of organic viticulture can be achieved by analyzing soil nematofauna

    OpenAIRE

    Coll, P; Le Cadre, E; Mérot, A; Villenave, C

    2013-01-01

    Soil nematofauna is a bioindicator that can highlight changes in biological functioning when changing agricultural practices. In the present study, the effects of conversion of vineyards to organic agriculture on biological soil quality were evaluated. Twenty four conventional plots and organic plots in Cruscades (Aude) were studied: they were divided into four groups: (1) conventional, (2) converted for 7 years (Bio 7 years), (3) converted for 11 years (Bio 11) and (4) converted for 17 (Bio ...

  11. 土壤结皮对大豆出苗的影响及黄淮海地区的关键解决技术%The Influence of Soil Crusting on Emergence of Soybean and Its Key Solution in Huang-Huai-Hai River Valley

    Institute of Scientific and Technical Information of China (English)

    武婷婷; 吴存祥

    2017-01-01

    大豆为子叶出土作物,土壤结皮严重影响大豆出苗质量.本文综述了土壤结皮的形成原因和过程、土壤结皮对土壤和农作物的影响.针对我国黄淮海地区土壤结皮给大豆出苗带来的不利影响,还简述了秸秆覆盖对抑制土壤结皮形成的作用效果,以期为黄淮海地区大豆的生产提供技术参考.%Soybean is a dicot crop and its emergence requires the pull of cotyledon out of soil surface.Soil crusting influences the quality of seed emergence.This review illustrates the cause of formation and process of soil crusting,influence of soil crusting on soil and crop and the inhibitive effect of straw-mulching on soil crusting.Due to the influence of soil crusting on soybean production in the Huang-Huai-Hai River Valley,this review may provide technique support for soybean production in this area.

  12. Potential of Biological Agents in Decontamination of Agricultural Soil

    Directory of Open Access Journals (Sweden)

    Muhammad Kashif Javaid

    2016-01-01

    Full Text Available Pesticides are widely used for the control of weeds, diseases, and pests of cultivated plants all over the world, mainly since the period after the Second World War. The use of pesticides is very extensive to control harm of pests all over the globe. Persistent nature of most of the synthetic pesticides causes serious environmental concerns. Decontamination of these hazardous chemicals is very essential. This review paper elaborates the potential of various biological agents in decontamination of agricultural soils. The agricultural crop fields are contaminated by the periodic applications of pesticides. Biodegradation is an ecofriendly, cost-effective, highly efficient approach compared to the physical and chemical methods which are expensive as well as unfriendly towards environment. Biodegradation is sensitive to the concentration levels of hydrogen peroxide and nitrogen along with microbial community, temperature, and pH changes. Experimental work for optimum conditions at lab scale can provide very fruitful results about specific bacterial, fungal strains. This study revealed an upper hand of bioremediation over physicochemical approaches. Further studies should be carried out to understand mechanisms of biotransformation.

  13. Potential of Biological Agents in Decontamination of Agricultural Soil.

    Science.gov (United States)

    Javaid, Muhammad Kashif; Ashiq, Mehrban; Tahir, Muhammad

    2016-01-01

    Pesticides are widely used for the control of weeds, diseases, and pests of cultivated plants all over the world, mainly since the period after the Second World War. The use of pesticides is very extensive to control harm of pests all over the globe. Persistent nature of most of the synthetic pesticides causes serious environmental concerns. Decontamination of these hazardous chemicals is very essential. This review paper elaborates the potential of various biological agents in decontamination of agricultural soils. The agricultural crop fields are contaminated by the periodic applications of pesticides. Biodegradation is an ecofriendly, cost-effective, highly efficient approach compared to the physical and chemical methods which are expensive as well as unfriendly towards environment. Biodegradation is sensitive to the concentration levels of hydrogen peroxide and nitrogen along with microbial community, temperature, and pH changes. Experimental work for optimum conditions at lab scale can provide very fruitful results about specific bacterial, fungal strains. This study revealed an upper hand of bioremediation over physicochemical approaches. Further studies should be carried out to understand mechanisms of biotransformation.

  14. Assessing Cross-disciplinary Efficiency of Soil Amendments for Agro-biologically, Economically, and Ecologically Integrated Soil Health Management

    Science.gov (United States)

    2010-01-01

    Preventive and/or manipulative practices will be needed to maintain soil's biological, physiochemical, nutritional, and structural health in natural, managed, and disturbed ecosystems as a foundation for food security and global ecosystem sustainability. While there is a substantial body of interdisciplinary science on understanding function and structure of soil ecosystems, key gaps must be bridged in assessing integrated agro-biological, ecological, economical, and environmental efficiency of soil manipulation practices in time and space across ecosystems. This presentation discusses the application of a fertilizer use efficiency (FUE) model for assessing agronomic, economic, ecological, environmental, and nematode (pest) management efficiency of soil amendments. FUE is defined as increase in host productivity and/or decrease in plant-parasitic nematode population density in response to a given fertilizer treatment. Using the effects of nutrient amendment on Heterodera glycines population density and normalized difference vegetative index (indicator of physiological activities) of a soybean cultivar ‘CX 252’, how the FUE model recognizes variable responses and separates nutrient deficiency and toxicity from nematode parasitism as well as suitability of treatments designed to achieve desired biological and physiochemical soil health conditions is demonstrated. As part of bridging gaps between agricultural and ecological approaches to integrated understanding and management of soil health, modifications of the FUE model for analyzing the relationships amongst nematode community structure, soil parameters (eg. pH, nutrients, %OM), and plant response to soil amendment is discussed. PMID:22736840

  15. Functional soil microbial diversity across Europe estimated by EEA, MicroResp and BIOLOG

    DEFF Research Database (Denmark)

    Winding, Anne; Rutgers, Michiel; Creamer, Rachel

    consisting of 81 soil samples covering five Biogeograhical Zones and three land-uses in order to test the sensitivity, ease and cost of performance and biological significance of the data output. The techniques vary in how close they are to in situ functions; dependency on growth during incubation......Soil microorganisms are abundant and essential for the bio-geochemical processes of soil, soil quality and soil ecosystem services. All this is dependent on the actual functions the microbial communities are performing in the soil. Measuring soil respiration has for many years been the basis...... of estimating soil microbial activity. However, today several techniques are in use for determining microbial functional diversity and assessing soil biodiversity: Methods based on CO2 development by the microbes such as substrate induced respiration (SIR) on specific substrates have lead to the development...

  16. Effect of soil type and soil management on soil physical, chemical and biological properties in commercial organic olive orchards in Southern Spain

    Science.gov (United States)

    Gomez, Jose Alfonso; Auxiliadora Soriano, Maria; Montes-Borrego, Miguel; Navas, Juan Antonio; Landa, Blanca B.

    2014-05-01

    One of the objectives of organic agriculture is to maintain and improve soil quality, while simultaneously producing an adequate yield. A key element in organic olive production is soil management, which properly implemented can optimize the use of rainfall water enhancing infiltration rates and controlling competition for soil water by weeds. There are different soil management strategies: eg. weed mowing (M), green manure with surface tillage in spring (T), or combination with animal grazing among the trees (G). That variability in soil management combined with the large variability in soil types on which organic olive trees are grown in Southern Spain, difficult the evaluation of the impact of different soil management on soil properties, and yield as well as its interpretation in terms of improvement of soil quality. This communications presents the results and analysis of soil physical, chemical and biological properties on 58 soils in Southern Spain during 2005 and 2006, and analyzed and evaluated in different studies since them. Those 58 soils were sampled in 46 certified commercial organic olive orchards with four soil types as well as 12 undisturbed areas with natural vegetation near the olive orchards. The four soil types considered were Eutric Regosol (RGeu, n= 16), Eutric Cambisol (CMeu, n=16), Calcaric Regosol (RGca, n=13 soils sampled) and Calcic Cambisol (CMcc), and the soil management systems (SMS) include were 10 light tillage (LT), 16 sheep grazing (G), 10 tillage (T), 10 mechanical mowing (M), and 12 undisturbed areas covered by natural vegetation (NV-C and NV-S). Our results indicate that soil management had a significant effect on olive yield as well as on key soil properties. Among these soil properties are physical ones, such as infiltration rate or bulk density, chemical ones, especially organic carbon concentration, and biological ones such as soil microbial respiration and bacterial community composition. Superimpose to that soil

  17. Soil biological shield exposed to high energy neutrons; Zemlja kao bioloski stit od neutrona visokih energija

    Energy Technology Data Exchange (ETDEWEB)

    Simovic, R; Marinkovic, N [Institute of nuclear sciences Vinca, Belgrade (Yugoslavia)

    1993-04-15

    Shielding efficiency of soil biological shield exposed to high energy neutrons was investigated. Dose rate equivalents for neutrons, secondary gamma and gamma radiation were computed on the surface of soil slabs having different thicknesses. Yields of primary and secondary nuclear radiation in the total dose were evaluated. Influence of the incident neutron spectrum, water content and chemical composition of the material on its shielding efficiency was examined. It was found that the soil density and the water content determine the quality of biological shield, the influence of other factors being less important. Comparison of shielding efficiencies for soil with sand, brick and ordinary concrete shields was done.

  18. Estimation of Corn Yield and Soil Nitrogen via Soil Electrical Conductivity Measurement Treated with Organic, Chemical and Biological Fertilizers

    Directory of Open Access Journals (Sweden)

    H. Khalilzade

    2016-02-01

    Full Text Available Introduction Around the world maize is the second crop with the most cultivated areas and amount of production, so as the most important strategic crop, have a special situation in policies, decision making, resources and inputs allocation. On the other side, negative environmental consequences of intensive consumption of agrochemicals resulted to change view concerning food production. One of the most important visions is sustainable production of enough food plus attention to social, economic and environmental aspects. Many researchers stated that the first step to achieve this goal is optimization and improvement of resources use efficiencies. According to little knowledge on relation between soil electrical conductivity and yield of maize, beside the environmental concerns about nitrogen consumption and need to replace chemical nitrogen by ecological inputs, this study designed and aimed to evaluate agroecological characteristics of corn and some soil characteristics as affected by application of organic and biological fertilizers under field conditions. Materials and Methods In order to probing the possibility of grain yield and soil nitrogen estimation via measurement of soil properties, a field experiment was conducted during growing season 2010 at Research Station, Ferdowsi University of Mashhad, Iran. A randomized complete block design (RCBD with three replications was used. Treatments included: 1- manure (30 ton ha-1, 2-vermicompost (10 ton ha-1, 3- nitroxin (containing Azotobacter sp. and Azospirillum sp., inoculation was done according to Kennedy et al., 4- nitrogen as urea (400 kg ha-1 and 5- control (without fertilizer. Studied traits were soil pH, soil EC, soil respiration rate, N content of soil and maize yield. Soil respiration rate was measured using equation 1: CO2= (V0- V× N×22 Equation 1 In which V0 is the volume of consumed acid for control treatment titration, V is of the volume of consumed acid for sample treatment

  19. Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation.

    Science.gov (United States)

    Liao, Yingping; Min, Xiaobo; Yang, Zhihui; Chai, Liyuan; Zhang, Shujuan; Wang, Yangyang

    2014-01-01

    Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils.

  20. Biologically Active Organic Matter in Soils of European Russia

    Science.gov (United States)

    Semenov, V. M.; Kogut, B. M.; Zinyakova, N. B.; Masyutenko, N. P.; Malyukova, L. S.; Lebedeva, T. N.; Tulina, A. S.

    2018-04-01

    Experimental and literature data on the contents and stocks of active organic matter in 200 soil samples from the forest-tundra, southern-taiga, deciduous-forest, forest-steppe, dry-steppe, semidesert, and subtropical zones have been generalized. Natural lands, agrocenoses, treatments of long-term field experiments (bare fallow, unfertilized and fertilized crop rotations, perennial plantations), and different layers of soil profile are presented. Sphagnum peat and humus-peat soil in the tundra and forest-tundra zones are characterized by a very high content of active organic matter (300-600 mg C/100 g). Among the zonal soils, the content of active organic matter increases from the medium (75-150 mg C/100 g) to the high (150-300 mg C/100 g) level when going from soddy-podzolic soil to gray forest and dark-gray forest soils and then to leached chernozem. In the series from typical chernozem to ordinary and southern chernozem and chestnut and brown semidesert soils, a decrease in the content of active organic matter to the low (35-75 mg C/100 g) and very low (organic matter. Most arable soils are mainly characterized by low or very low contents of active organic matter. In the upper layers of soils, active organic matter makes up 1.2-11.1% of total Corg. The profile distribution of active organic matter in the studied soils coincides with that of Corg: their contents appreciably decrease with depth, except for brown semidesert soil. The stocks of active organic matter vary from 0.4 to 5.4 t/ha in the layer of 0-20 cm and from 1.0 to 12.4/ha in the layer of 0-50 cm of different soil types.

  1. Mind the gap: non-biological processes contributing to soil CO2 efflux.

    Science.gov (United States)

    Rey, Ana

    2015-05-01

    Widespread recognition of the importance of soil CO2 efflux as a major source of CO2 to the atmosphere has led to active research. A large soil respiration database and recent reviews have compiled data, methods, and current challenges. This study highlights some deficiencies for a proper understanding of soil CO2 efflux focusing on processes of soil CO2 production and transport that have not received enough attention in the current soil respiration literature. It has mostly been assumed that soil CO2 efflux is the result of biological processes (i.e. soil respiration), but recent studies demonstrate that pedochemical and geological processes, such as geothermal and volcanic CO2 degassing, are potentially important in some areas. Besides the microbial decomposition of litter, solar radiation is responsible for photodegradation or photochemical degradation of litter. Diffusion is considered to be the main mechanism of CO2 transport in the soil, but changes in atmospheric pressure and thermal convection may also be important mechanisms driving soil CO2 efflux greater than diffusion under certain conditions. Lateral fluxes of carbon as dissolved organic and inorganic carbon occur and may cause an underestimation of soil CO2 efflux. Traditionally soil CO2 efflux has been measured with accumulation chambers assuming that the main transport mechanism is diffusion. New techniques are available such as improved automated chambers, CO2 concentration profiles and isotopic techniques that may help to elucidate the sources of carbon from soils. We need to develop specific and standardized methods for different CO2 sources to quantify this flux on a global scale. Biogeochemical models should include biological and non-biological CO2 production processes before we can predict the response of soil CO2 efflux to climate change. Improving our understanding of the processes involved in soil CO2 efflux should be a research priority given the importance of this flux in the global

  2. Chemical, physical and biological characteristics of urban soils. Chapter 7

    Science.gov (United States)

    Richard V. Pouyat; Katalin Szlavecz; Ian D. Yesilonis; Peter M. Groffman; Kirsten. Schwarz

    2010-01-01

    Urban soils provide an array of ecosystem services to inhabitants of cities and towns. Urbanization affects soils and their capacity to provide ecosystem services directly through disturbance and management (e.g., irrigation) and indirectly through changes in the environment (e.g., heat island effect and pollution). Both direct and indirect effects contribute to form a...

  3. Biological active compounds from actinomycetes isolated from soil ...

    African Journals Online (AJOL)

    sunny

    2014-12-03

    Dec 3, 2014 ... Key words: Actinomycetes, anthracnose, bioactivity, biodiversity, Malaysia. INTRODUCTION. Soil microbes which had been known to possess the ability to act as degradation and biocontrol agents have been widely studied by researchers around the world. One of these well-known soil microbes are the.

  4. CONSIDERATIONS ON URBAN SOILS

    Directory of Open Access Journals (Sweden)

    Radu Lacatusu

    2005-10-01

    Full Text Available Urban soil is an material that has been manipulated, disturbed or transported by man’s activities in the urban environment and is used as a medium for plant growth and for constructions. The physical, chemical, and biological properties are generally less favorable as a rooting medium than soil found on the natural landscape. The main characteristics of urban soils are: great vertical and spatial variability; modified soil structure leading to compaction; presence of a surface crust; modified soil reaction, usually elevated; restricted aeration and water drainage; modified abundance of chemical elements, interrupted nutrient cycling and soil organism activity; presence of anthropic materials contaminants and pollutants; modified soil temperature regime. The urbic horizon is designated as U (always capital letter and for indication of processes are used different small letters. It is necessary elaboration a new classification of urban soils for our country.

  5. Remediation of Biological Organic Fertilizer and Biochar in Paddy Soil Contaminated by Cd and Pb

    Directory of Open Access Journals (Sweden)

    MA Tie-zheng

    2015-02-01

    Full Text Available The effect of application of biological organic fertilizer and biochar on the immobilized remediation of paddy soil contaminated by Cd and Pb was studied under the field experiment. The results showed that biological organic fertilizer and biochar increased the soil pH and soil nutrient contents, and reduced the soil available Cd and Pb concentrations significantly. The soil pH had significantly negative correla-tion with the soil available Cd and Pb contents. The application of biological organic fertilizer and biochar decreased Cd and Pb concentration in all parts of the rice plant, with Cd concentration in brown rice decrease by 22.00% and 18.34% and Pb decease in brown rice by 33.46% and 12.31%. The concentration of Cd and Pb in brown rice had significant positive correlation with the soil available Cd and Pb concentra-tions. It was observed that both biological organic fertilizer and biochar had a positive effect on the remediation of paddy soil contaminated by Cd and Pb.

  6. The accumulation of 137Cs in the biological compartment of forest soils

    International Nuclear Information System (INIS)

    Nikolova, Ivanka; Johanson, Karl J.; Clegg, Stephen

    2000-01-01

    Soil samples were collected in various forest stands, located about 40 km north-west from Uppsala. The various stands were: (1) Clear cut area made in 1987, (2) Normal forest with 50-100 old Norway spruce and Scots pine and with a thick humic layer of about 10 cm; (3) Raised bog with 50-year-old Scots pine and Sphagnum moss layer over peat soil. (4) Rocky area with old Scots pine, growing on a shallow soil, mainly of organic origin. (5) Normal forest with nearly 100-year-old spruce and pine, growing a shallow humic layer over sandy soil. Soil blocks of about 20x20 cm and down to a depth of 10-15 cm were collected on each site. The soil samples were mechanically separated into various fractions: bulk, rhizosphere and soil-root interface. The results showed that 137 Cs was unevenly distributed between the three soil fractions. The highest activity concentrations -- 3-4 times higher than in the other two fractions -- as well as the highest organic content -- usually more than 95% -- were found in the soil-root interface fraction. Of the total 137 Cs activity in the soil, 18% as a mean value was found in the soil-root interface fraction. The results thus show that a substantial fraction of the 137 Cs in the soils in some way associated with the biological part of the soil, probably with the fungal component

  7. Application of radiochemical methods for development of new biological preparation designed for soil bioremediation

    International Nuclear Information System (INIS)

    Kim, A.A.; Djuraeva, G.T.; Djumaniyazova, G.I.; Yadgarov, Kh.T.

    2006-01-01

    Full text: Internationally the bioremediation of agricultural lands contaminated by persistent chloroorganic compounds by means of the microbial methods are used as the most low-cost and the most effective. One of the factors reducing efficacy of microbial degradation, is often the low quantity of microorganisms - destructors in the soil. Therefore, we have designed bioremediation technology of soils, contaminated by organochlorine compounds, with use of the alive microorganisms as active agent. We developed the biological preparation containing 5 aboriginal active strains of bacteria - destructors of persistent chloroorganic compounds and investigated the ability of biological preparation to increase the bioremediation potential of contaminated soils. To carry out the investigation we developed the complex of radiochemical methods with use of tritium labeled PCBs, including the following methods: 1.The method to define the accumulation and degradation of PCBs in soil bacteria in culture allows determination of quantitative characteristics of bacterial strains. 2. The method to define the PCBs degradation by soil bacteria strains in model conditions in the soil allows to estimate the PCB-destructive activity of strains after introducing in soil. 3. A method to define the PCB-destructive activity of own microbiota of contaminated soil. 4. A method to define the effect of stimulation of the PCB-destructive activity of biological preparation and own microbiota of soil with the help of biofertilizers. By using the developed radiochemical methods we have carried out investigation on creation of new biological preparation on the basis of strains of soil bacteria - destructors of PCBs. We also determined the quality and quantity characteristics of HCCH and PCBs-destructive activity of new biological preparation. It is shown that the new biological preparation is capable of accumulation and destruction of the PCBs in culture and in soil at model conditions. Thus, the

  8. Biological Treatment of Petroleum in Radiologically Contaminated Soil

    Energy Technology Data Exchange (ETDEWEB)

    BERRY, CHRISTOPHER

    2005-11-14

    This chapter describes ex situ bioremediation of the petroleum portion of radiologically co-contaminated soils using microorganisms isolated from a waste site and innovative bioreactor technology. Microorganisms first isolated and screened in the laboratory for bioremediation of petroleum were eventually used to treat soils in a bioreactor. The bioreactor treated soils contaminated with over 20,000 mg/kg total petroleum hydrocarbon and reduced the levels to less than 100 mg/kg in 22 months. After treatment, the soils were permanently disposed as low-level radiological waste. The petroleum and radiologically contaminated soil (PRCS) bioreactor operated using bioventing to control the supply of oxygen (air) to the soil being treated. The system treated 3.67 tons of PCRS amended with weathered compost, ammonium nitrate, fertilizer, and water. In addition, a consortium of microbes (patent pending) isolated at the Savannah River National Laboratory from a petroleum-contaminated site was added to the PRCS system. During operation, degradation of petroleum waste was accounted for through monitoring of carbon dioxide levels in the system effluent. The project demonstrated that co-contaminated soils could be successfully treated through bioventing and bioaugmentation to remove petroleum contamination to levels below 100 mg/kg while protecting workers and the environment from radiological contamination.

  9. Heavy Metal Contaminated Soil Imitation Biological Treatment Overview

    Science.gov (United States)

    Pan, Chang; Chen, Jun; Wu, Ke; Zhou, Zhongkai; Cheng, Tingting

    2018-01-01

    In this paper, the treatment methods of heavy metal pollution in soils were analyzed, the existence and transformation of heavy metals in soil were explored, and the mechanism of heavy metal absorption by plants was studied. It was concluded that the main form of plants absorb heavy metals in the soil is exchangeable. The main mechanism was that the plant cell wall can form complex with heavy metals, so that heavy metals fixed on the cell wall, and through the selective absorption of plasma membrane into the plant body. In addition, the adsorption mechanism of the adsorbed material was analyzed. According to the results of some researchers, it was found that the mechanism of adsorption of heavy metals was similar to that of plants. According to this, using adsorbent material as the main material, Imitate the principle of plant absorption of heavy metals in the soil to removing heavy metals in the soil at one-time and can be separated from the soil after adsorption to achieve permanent removal of heavy metals in the soil was feasibility.

  10. Oxidoreductases and cellulases in lichens: possible roles in lichen biology and soil organic matter turnover.

    Science.gov (United States)

    Beckett, Richard P; Zavarzina, Anna G; Liers, Christiane

    2013-06-01

    Lichens are symbiotic associations of a fungus (usually an Ascomycete) with green algae and/or a cyanobacterium. They dominate on 8 % of the world's land surface, mainly in Arctic and Antarctic regions, tundra, high mountain elevations and as components of dryland crusts. In many ecosystems, lichens are the pioneers on the bare rock or soil following disturbance, presumably because of their tolerance to desiccation and high temperature. Lichens have long been recognized as agents of mineral weathering and fine-earth stabilization. Being dominant biomass producers in extreme environments they contribute to primary accumulation of soil organic matter. However, biochemical role of lichens in soil processes is unknown. Our recent research has demonstrated that Peltigeralean lichens contain redox enzymes which in free-living fungi participate in lignocellulose degradation and humification. Thus lichen enzymes may catalyse formation and degradation of soil organic matter, particularly in high-stress communities dominated by lower plants. In the present review we synthesize recently published data on lichen phenol oxidases, peroxidases, and cellulases and discuss their possible roles in lichen physiology and soil organic matter transformations. Copyright © 2013 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  11. Sustainable Materials Management (SMM) Web Academy Webinar: Compost from Food Waste: Understanding Soil Chemistry and Soil Biology on a College/University Campus

    Science.gov (United States)

    This page contains information about the Sustainable Materials Management (SMM) Web Academy Webinar Series titled Compost from Food Waste:Understanding Soil Chemistry and Soil Biology on a College/University Campus

  12. Engineering of Soil Biological Quality from Nickel Mining Stockpile Using Two Earthworm Ecological Groups

    Directory of Open Access Journals (Sweden)

    L M H Kilowasid

    2015-04-01

    Full Text Available Earthworms have the ability in modifying soil biological quality for plant growth. Their ability is mostly depending on its ecological groups. The objectives of the research were to study the influence of two ecological groups of earthworms on soil microbial activity and soil micro-fauna abundance, and to know the potential of soil modified by earthworms as plant growth medium. Eight combination of individual earthworm from epigeic and endogeic groups was applied into pot that was filled by soil from two years of nickel stockpile and each treatment was repeated by five times. The experiment was following complete randomize design procedure. After sixteen days of research, the soil sample from each pot was analyzed for soil FDA activity, number of flagellate and nematodes. Furthermore, one kg of the soil from each pot was taken and every pot was grown by Paraserianthes falcataria seedling with the age of five days and continued its growth for two months. The results indicated that the soil FDA activity, number of flagellate and nematodes among treatments were significantly differences. In addition, it indicated the significant differences in dry weight of shoot, root, total plant, and root to shoot ratio of P. falcataria seedlings. It concluded that the combination of an individual number of epigeic and endogeic earthworms improved soil biological quality of stock pile, amd most suitable for seedlings growth in nickel mining area.

  13. Akttvitas Selulase, Amilase Dan Invertase Pada Tanah Kebun Biologi Wamena*[cellulase, Amylase and Invertase Activities Achieved From Soil of Wamena Biological Research Station

    OpenAIRE

    Rahmansyah, M; Latupapua, HJD

    2003-01-01

    Enzymatic activities in soil as due to microbes action in organic matter degradation, lead to propose as indicators for determining soil degree enrichment.In this work, the enzymatic activities of cellulase, invertase and amylase were determined in tropical soil collected from Biological Research Station in Wamena. Result of measurement on five soil samples showed that cellulase activity occurred between 0.10 - 0.31 mg reducing sugar/g soil/hour in 2% Carboxymethylcellulose (CMC) substrate, a...

  14. Evaluation of biological attributes of soil type latossol under agroecological production

    Directory of Open Access Journals (Sweden)

    Marisol Rivero Herrada

    2016-10-01

    Full Text Available Biological soil attributes have shown to be good indicators of soil changes as a result of the management function. The aim of this study was to evaluate the effect of using cover crops, as well as planting and tillage systems on the biological attributes of a yellowish red latosol soil. Soil samples were taken at 0 to 0.10 m depth, seven days before the bean harvest. Microbial biomass carbon and nitrogen, basal soil respiration, metabolic ratio and total enzyme activity were evaluated in this study. The best agroecological management was achieved under the association of the ground cover with millet and in direct seeding because they showed higher soil microbial biomass carbon and nitrogen content and lower metabolic quotient, being pork bean the best plant coverage. All biological soil attributes were sensitive to the tillage system, which showed the best results of the total enzyme activity and of the soil metabolic quotient which resulted to be the most efficient.

  15. Natural physical and biological processes compromise the long-term performance of compacted soil caps

    International Nuclear Information System (INIS)

    Smith, E.D.

    1995-01-01

    Compacted soil barriers are components of essentially all caps placed on closed waste disposal sites. The intended functions of soil barriers in waste facility caps include restricting infiltration of water and release of gases and vapors, either independently or in combination with synthetic membrane barriers, and protecting other manmade or natural barrier components. Review of the performance of installed soil barriers and of natural processes affecting their performance indicates that compacted soil caps may function effectively for relatively short periods (years to decades), but natural physical and biological processes can be expected to cause them to fail in the long term (decades to centuries). This paper addresses natural physical and biological processes that compromise the performance of compacted soil caps and suggests measures that may reduce the adverse consequences of these natural failure mechanisms

  16. Soil and surface layer type affect non-rainfall water inputs

    Science.gov (United States)

    Agam, Nurit; Berliner, Pedro; Jiang, Anxia

    2017-04-01

    Non-rainfall water inputs (NRWIs), which include fog deposition, dew formation, and direct water vapor adsorption by the soil, play a vital role in arid and semiarid regions. Environmental conditions, namely radiation, air temperature, air humidity, and wind speed, largely affect the water cycle driven by NRWIs. The substrate type (soil type and the existence/absence of a crust layer) may as well play a major role. Our objective was to quantify the effects of soil type (loess vs. sand) and surface layer (bare vs. crusted) on the gain and posterior evaporation of NRWIs in the Negev Highlands throughout the dry summer season. Four undisturbed soil samples (20 cm diameter and 50 cm depth) were excavated and simultaneously introduced into a PVC tube. Two samples were obtained in the Negev's Boker plain (loess soil) and two in the Nizzana sand dunes in the Western Negev. On one sample from each site the crust was removed while on the remaining one the natural crust was left in place. The samples were brought to the research site at the Jacob Bluestein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel (31˚08' N, 34˚53' E, 400 meter above the sea level) where they were exposed to the same environmental conditions. The four samples in their PVC tubes were placed on top of scales and the samples mass was continuously monitored. Soil temperatures were monitored at depths of 1, 2, 3, 5 and10 cm in each microlysimeter (ML) using Copper-Constantan thermocouples. The results of particle size distribution indicated that the crust of the loess soil is probably a physical crust, i.e., a crust that forms due to raindroplets impact; while the crust on the sand soil is biological. On most days, the loess soils adsorbed more water than their corresponding sand soil samples. For both soils, the samples for which the crust was removed adsorbed more water than the samples for which it was intact. The difference in daily water adsorption amount between crusted

  17. [Effects and Biological Response on Bioremediation of Petroleum Contaminated Soil].

    Science.gov (United States)

    Yang, Qian; Wu, Man-li; Nie, Mai-qian; Wang, Ting-ting; Zhang, Ming-hui

    2015-05-01

    Bioaugmentation and biostimulation were used to remediate petroleum-contaminated soil which were collected from Zichang city in North of Shaanxi. The optimal bioremediation method was obtained by determining the total petroleum hydrocarbon(TPH) using the infrared spectroscopy. During the bioremediation, number of degrading strains, TPH catabolic genes, and soil microbial community diversity were determined by Most Probable Number (MPN), polymerase chain reaction (PCR) combined agarose electrophoresis, and PCR-denaturing gradient electrophoresis (DGGE). The results in different treatments showed different biodegradation effects towards total petroleum hydrocarbon (TPH). Biostimulation by adding N and P to soils achieved the best degradation effects towards TPH, and the bioaugmentation was achieved by inoculating strain SZ-1 to soils. Further analysis indicated the positive correlation between catabolic genes and TPH removal efficiency. During the bioremediation, the number of TPH and alkanes degrading strains was higher than the number of aromatic degrading strains. The results of PCR-DGGE showed microbial inoculums could enhance microbial community functional diversity. These results contribute to understand the ecologically microbial effects during the bioremediation of petroleum-polluted soil.

  18. Biological and chemical assessments of zinc ageing in field soils

    International Nuclear Information System (INIS)

    Donner, Erica; Broos, Kris; Heemsbergen, Diane; Warne, Michael St. J.; McLaughlin, Mike J.; Hodson, Mark E.; Nortcliff, Stephen

    2010-01-01

    As zinc (Zn) is both an essential trace element and potential toxicant, the effects of Zn fixation in soil are of practical significance. Soil samples from four field sites amended with ZnSO 4 were used to investigate ageing of soluble Zn under field conditions over a 2-year period. Lability of Zn measured using 65 Zn radioisotope dilution showed a significant decrease over time and hence evidence of Zn fixation in three of the four soils. However, 0.01 M CaCl 2 extractions and toxicity measurements using a genetically modified lux-marked bacterial biosensor did not indicate a decrease in soluble/bioavailable Zn over time. This was attributed to the strong regulatory effect of abiotic properties such as pH on these latter measurements. These results also showed that Zn ageing occurred immediately after Zn spiking, emphasising the need to incubate freshly spiked soils before ecotoxicity assessments. - Ageing effects were detected in Zn-amended field soils using 65 Zn isotopic dilution as a measure of lability, but not with either CaCl 2 extractions or a lux-marked bacterial biosensor.

  19. Rainfall intensity effects on crusting and mode of seedling ...

    African Journals Online (AJOL)

    Predicted changes in rainfall intensity due to climate change are likely to influence key soil health parameters, especially structural attributes and crop growth. Variations in rainfall intensity will impact crop ... and growth in these soils. Keywords: climate change, crusting, mineralogy, penetration resistance, soil organic matter ...

  20. Tillage and Farmyard Manure Effects on Crusting and Compacting ...

    African Journals Online (AJOL)

    Seasonal rainwater losses through increased runoff volumes reduce soil moisture and hence result in agricultural drought. The objective of this study was to examine the hydrological effects of two tillage practices with and without farmyard manure on surface runoff and soil loss of crusting and compacting soils under field ...

  1. Remediation of soil/concrete contaminated with uranium and radium by biological method

    International Nuclear Information System (INIS)

    Gye-Nam Kim; Seung-Su Kim; Hye-Min Park; Won-Suk Kim; Uk-Ryang Park; Jei-Kwon Moon

    2013-01-01

    Biological method was studied for remediation of soil/concrete contaminated with uranium and radium. Optimum experiment conditions for mixing ratios of penatron and soil, and the pH of soil was obtained through several bioremediations with soil contaminated with uranium and radium. It was found that an optimum mixing ratio of penatron for bioremediation of uranium soil was 1 %. Also, the optimum pH condition for bioremediation of soil contaminated with uranium and radium was 7.5. The removal efficiencies of uranium and radium from higher concentration of soil were rather reduced in comparison with those from lower concentration of soil. Meanwhile, the removal of uranium and radium in concrete by bioremediation is possible but the removal rate from concrete was slower than that from soil. The removal efficiencies of uranium and radium from soil under injection of 1 % penatron at pH 7.5 for 120 days were 81.2 and 81.6 %, respectively, and the removal efficiencies of uranium and radium from concrete under the same condition were 63.0 and 45.2 %, respectively. Beyond 30 days, removal rates of uranium and radium from soil and concrete by bioremediation was very slow. (author)

  2. Corium crust strength measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lomperski, S. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439-4840 (United States)], E-mail: lomperski@anl.gov; Farmer, M.T. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439-4840 (United States)], E-mail: farmer@anl.gov

    2009-11-15

    Corium strength is of interest in the context of a severe reactor accident in which molten core material melts through the reactor vessel and collects on the containment basemat. Some accident management strategies involve pouring water over the melt to solidify it and halt corium/concrete interactions. The effectiveness of this method could be influenced by the strength of the corium crust at the interface between the melt and coolant. A strong, coherent crust anchored to the containment walls could allow the yet-molten corium to fall away from the crust as it erodes the basemat, thereby thermally decoupling the melt from the coolant and sharply reducing the cooling rate. This paper presents a diverse collection of measurements of the mechanical strength of corium. The data is based on load tests of corium samples in three different contexts: (1) small blocks cut from the debris of the large-scale MACE experiments, (2) 30 cm-diameter, 75 kg ingots produced by SSWICS quench tests, and (3) high temperature crusts loaded during large-scale corium/concrete interaction (CCI) tests. In every case the corium consisted of varying proportions of UO{sub 2}, ZrO{sub 2}, and the constituents of concrete to represent a LWR melt at different stages of a molten core/concrete interaction. The collection of data was used to assess the strength and stability of an anchored, plant-scale crust. The results indicate that such a crust is likely to be too weak to support itself above the melt. It is therefore improbable that an anchored crust configuration could persist and the melt become thermally decoupled from the water layer to restrict cooling and prolong an attack of the reactor cavity concrete.

  3. Short-term effects of different organic amendments on soil chemical, biochemical and biological indicators

    Science.gov (United States)

    Mondelli, Donato; Aly, Adel; Yirga Dagnachew, Ababu; Piscitelli, Lea; Dumontet, Stefano; Miano, Teodoro

    2014-05-01

    The limited availability of animal manure and the high cost of good quality compost lead to difficult soil quality management under organic agriculture. Therefore, it is important to find out alternative organic soil amendments and more flexible strategies that are able to sustain crop productivity and maintain and enhance soil quality. A three years study was carried out in the experimental fields of the Mediterranean Agronomic Institute of Bari located in Valenzano, Italy. The main objective of this research is to investigate the effects of different fertility management strategies on soil quality in order to estimate the role of innovative matrices for their use in organic farming. The experiment consists of seven treatments applied to a common crop rotation. The treatments include alternative organic amendments (1- olive mill wastewater OMW, 2- residues of mushroom cultivation MUS, 3- coffee chaff COF), common soil amendments (4- compost COM, 5- faba bean intercropping LEG, 6- cow manure - MAN) and as a reference treatment (7- mineral fertilizer COV). The soil quality was assessed before and after the application of the treatments, through biological (microbial biomass carbon and nitrogen, soil respiration and metabolic quotient), biochemical (soil enzymatic activities: β-glucosidase, alkaline phospatase, urease, fluorescein diacetate (FDA) hydrolysis), and chemical (pH, soil organic carbon, soil organic matter, total nitrogen, available phosphorous, exchangeable potassium, dissolved organic carbon and total dissolved nitrogen) indicators. Based on the results obtained after the second year, all treatments were able to improve various soil chemical parameters as compared to mineral fertilizer. The incorporation of COF and OMW seemed to be more effective in improving soil total N and exchangeable K, while MAN significantly increased available P. All the amendments enhance dissolved organic C, soil respiration, microbial biomass and metabolic quotient as

  4. Biologically induced formation of realgar deposits in soil

    Czech Academy of Sciences Publication Activity Database

    Drahota, P.; Mikutta, C.; Falteisek, L.; Duchoslav, V.; Klementová, Mariana

    2017-01-01

    Roč. 218, DEC (2017), s. 237-256 ISSN 0016-7037 Institutional support: RVO:61388980 Keywords : Arsenic speciation * Microbial communities * Realgar * Sulfur isotopes * Wetland soil * X-ray absorption spectroscopy Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 4.609, year: 2016

  5. Biological remediation of oil contaminated soil with earthworms Eisenia andrei

    Science.gov (United States)

    Chachina, S. B.; Voronkova, N. A.; Baklanova, O. N.

    2017-08-01

    The study was performed on the bioremediation efficiency of the soil contaminated with oil (20 to 100 g/kg), petroleum (20 to 60 g/kg) and diesel fuel (20 to 40 g/kg) with the help of earthworms E. andrei in the presence of bacteria Pseudomonas, nitrogen fixing bacteria Azotobacter and Clostridium, yeasts Saccharomyces, fungi Aspergillus and Penicillium, as well as Actinomycetales, all being components of biopreparation Baykal-EM. It was demonstrated that in oil-contaminated soil, the content of hydrocarbons decreased by 95-97% after 22 weeks in the presence of worms and bacteria. In petroleum-contaminated soil the content of hydrocarbons decreased by 99% after 22 weeks. The presence of the diesel fuel in the amount of 40 g per 1 kg soil had an acute toxic effect and caused the death of 50 % earthworm species in 14 days. Bacteria introduction enhanced the toxic effect of the diesel fuel and resulted in the death of 60 % earthworms after 7 days.

  6. Implications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert

    Directory of Open Access Journals (Sweden)

    Becky A. Ball

    2011-12-01

    Full Text Available The McMurdo Dry Valleys are one of the most arid environments on Earth. Over the soil landscape for the majority of the year, biological and ecosystem processes in the dry valleys are constrained by the low temperatures and limited availability of water. The prevalence of these physical limitations in controlling biological and ecosystem processes makes the dry valleys a climate-sensitive system, poised to experience substantial changes following projected future warming. Short-duration increases in summer temperatures are associated with pulses of water from melting ice reserves, including glaciers, snow and permafrost. Such pulses alter soil geochemistry by mobilizing and redistributing soil salts (via enhanced weathering, solubility and mobility, which can alter habitat suitability for soil organisms. Resulting changes in soil community composition or distribution may alter the biogeochemical processes in which they take part. Here, we review the potential impacts of meltwater pulses and present new field data documenting instances of meltwater pulse events that result from different water sources and hydrological patterns, and discuss their potential influence on soil biology and biogeochemistry. We use these examples to discuss the potential impacts of future climate change on the McMurdo Dry Valley soil ecosystem.

  7. Ecological drivers of soil microbial diversity and soil biological networks in the Southern Hemisphere.

    Science.gov (United States)

    Delgado-Baquerizo, Manuel; Reith, Frank; Dennis, Paul G; Hamonts, Kelly; Powell, Jeff R; Young, Andrew; Singh, Brajesh K; Bissett, Andrew

    2018-03-01

    The ecological drivers of soil biodiversity in the Southern Hemisphere remain underexplored. Here, in a continental survey comprising 647 sites, across 58 degrees of latitude between tropical Australia and Antarctica, we evaluated the major ecological patterns in soil biodiversity and relative abundance of ecological clusters within a co-occurrence network of soil bacteria, archaea and eukaryotes. Six major ecological clusters (modules) of co-occurring soil taxa were identified. These clusters exhibited strong shifts in their relative abundances with increasing distance from the equator. Temperature was the major environmental driver of the relative abundance of ecological clusters when Australia and Antarctica are analyzed together. Temperature, aridity, soil properties and vegetation types were the major drivers of the relative abundance of different ecological clusters within Australia. Our data supports significant reductions in the diversity of bacteria, archaea and eukaryotes in Antarctica vs. Australia linked to strong reductions in temperature. However, we only detected small latitudinal variations in soil biodiversity within Australia. Different environmental drivers regulate the diversity of soil archaea (temperature and soil carbon), bacteria (aridity, vegetation attributes and pH) and eukaryotes (vegetation type and soil carbon) across Australia. Together, our findings provide new insights into the mechanisms driving soil biodiversity in the Southern Hemisphere. © 2018 by the Ecological Society of America.

  8. Chemical and biological attributes of a lowland soil affected by land leveling

    Directory of Open Access Journals (Sweden)

    José Maria Barbat Parfitt

    2013-11-01

    Full Text Available The objective of this work was to evaluate the relationship between soil chemical and biological attributes and the magnitude of cuts and fills after the land leveling process of a lowland soil. Soil samples were collected from the 0 - 0.20 m layer, before and after leveling, on a 100 point grid established in the experimental area, to evaluate chemical attributes and soil microbial biomass carbon (MBC. Leveling operations altered the magnitude of soil chemical and biological attributes. Values of Ca, Mg, S, cation exchange capacity, Mn, P, Zn, and soil organic matter (SOM decreased in the soil profile, whereas Al, K, and MBC increased after leveling. Land leveling decreased in 20% SOM average content in the 0 - 0.20 m layer. The great majority of the chemical attributes did not show relations between their values and the magnitude of cuts and fills. The relation was quadratic for SOM, P, and total N, and was linear for K, showing a positive slope and indicating increase in the magnitude of these attributes in cut areas and stability in fill areas. The relationships between these chemical attributes and the magnitude of cuts and fills indicate that the land leveling map may be a useful tool for degraded soil recuperation through amendments and organic fertilizers.

  9. Application of MCPA herbicide on soils amended with biostimulants: short-time effects on soil biological properties.

    Science.gov (United States)

    Tejada, Manuel; García-Martínez, Ana M; Gómez, Isidoro; Parrado, Juan

    2010-08-01

    In this paper we studied in the laboratory the effect of MCPA herbicide at a rate of 1.5lha(-1) (manufactures rate recommended) on biological properties of a Plagic Antrosol amended with four biostimulants (WCDS, wheat condensed distillers soluble; PA-HE, hydrolyzed poultry feathers; CGHE, carob germ enzymatic extract; and RB, rice bran extract). Seven hundred grams of soil were mixed with WCDS at a rate of 10%, CGHE at a rate of 4.7%, PA-HE at a rate of 4.3%, and RB at a rate of 4.4%, respectively, in order to applying the same amount of organic matter to the soil (16.38 g organic matter). An unamended polluted and amended non-polluted soil were used as control. For all treatments, the soil ergosterol, dehydrogenase, urease, and phosphatase activities were measured at two incubation times (0 and 60 d). The 16S rDNA-DGGE profiles in all treatments were determined at the beginning and end of the incubation period. The results indicated that at the end of the incubation period and compared with the control soil, the dehydrogenase, urease and phosphatase activities and ergosterol decreased 39.3%, 20%, 15.7% and 56.5%, respectively in the non-organic amended polluted soil. The application of organic matter to unpolluted soil increased the enzymatic activities and ergosterol. However, this stimulation was higher in the soil amended with RB, followed by PA-HE, WCDS and CGHE. The application of herbicide in organic-amended soils decreased the enzymatic activities and ergosterol content. However, this decrease was lower than for the non-amended herbicide polluted soil. Possibly the low molecular weight protein content easily assimilated by soil microorganisms and the adsorption capacity of humic substances are responsible for less inhibition of these enzyme activities and soil ergosterol. The 16S rDNA-DGGE profiles indicated that herbicide did not negatively affect soil bacterial biodiversity. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  10. Non-rainfall water sources in the topsoil and their changes during formation of man-made algal crusts at the eastern edge of Qubqi Desert, Inner Mongolia.

    Science.gov (United States)

    Lan, ShuBin; Hu, ChunXiang; Rao, BenQiang; Wu, Li; Zhang, DeLu; Liu, YongDing

    2010-09-01

    In arid and semiarid areas, water uptake (non-rainfall water) serves as an important water source for plants, biological soil crusts, insects and small animals. In this study, a measurement program was undertaken to investigate water uptake and its changes during formation of man-made algal crusts in the Qubqi Desert. In the study region, water uptake from the atmosphere accounted for 25.07%-39.83% of the total water uptake, and was mainly taken up by a water vapor adsorption mechanism; the proportion of water uptake from the soil substrate was much higher (60.17%-74.93%). The formation of crusts promoted water uptake, but the increased uptake did not occur immediately after inoculation or crusts formation. The water taken up from the atmosphere increased significantly from day 15 after inoculation, and the soil water content was markedly enhanced from day 20 after inoculation. It is considered that the growth of algal filaments and their secretions were the main factors increasing the amount of water uptake and water content in the crusts, and these variables increased even during dry periods when some algae are likely to have died.

  11. Study of Effects of Sorghum Cultivation on Some Soil Biological Indicators at Different Zinc Levels

    Directory of Open Access Journals (Sweden)

    S. Bagheri

    2015-06-01

    Full Text Available Zinc is an essential element for plant growth which its high concentrations can cause pollution and toxicity in plant. In this study, the effects of sorghum cultivation on some indicators of microbial activity and its association with increased zinc concentrations in two soils with relatively similar physical and chemical properties, but different in concentration of heavy metals were investigated. In both soils zinc levels were added to obtain 250, 375 and 500 mg kg-1 (based on the initial nitric acid extractable content. Using plastic boxes containing 8 kg of soil, growth boxes (Rhizobox were prepared. The box interior was divided into three sections S1 (the rhizosphere, S2 (adjacent to the rhizosphere and S3 (bulk soil using nylon net plates. The results showed that at all levels of zinc in both soil types, BCF were bigger than units, so using this indicator, sorghum can be considered as a plant for accumulation of zinc. Microbial respiration and dehydrogenase activity was reduced in all sections adjacent to root in the polluted soil. It is generally understood that substrates and inhibitors (heavy metals compete in the formation of substrate-enzyme and inhibitor-enzyme complexes, but the effects of sorghum cultivation in increasing biological and enzyme activity indexes in soil 1 (non-polluted was higher than soil 2 (polluted, perhaps due to improvements in microbial activity in the vicinity of the roots, even in concentration higher than stress condition levels for zinc in soil.

  12. Phytoecological indicators for biological recultivation of soils polluted with oil in the Absheron peninsula

    Directory of Open Access Journals (Sweden)

    E. M. Gurbanov

    2009-07-01

    Full Text Available Phytoecological indicators of polluted soils of Amirov Oil-and-Gas Production Department (Garadag district,Baku were studied. Phytocenological and biomorphological analysis of flora was done with the aim of further biological rehabilitation of Absheron peninsula. Oil products (black oil, boring waters, etc. pollution turns the plant cover into a dead mass. Decontamination of soil and rehabilitation of microbial community improve the soil’s fertility. Wild and cultured plant indicators may be used in biopurification of the soils polluted with oil products. Sowing of the fodder crops followed by the technical remediation forms the clean areas of higher productivity.

  13. In situ phytoextraction of copper and cadmium and its biological impacts in acidic soil.

    Science.gov (United States)

    Cui, Hongbiao; Fan, Yuchao; Yang, John; Xu, Lei; Zhou, Jing; Zhu, Zhenqiu

    2016-10-01

    Phytoremediation is a potential cost-effective technology for remediating heavy metal-contaminated soils. In this study, we evaluated the biomass and accumulation of copper (Cu) and cadmium (Cd) of plant species grown in a contaminated acidic soil treated with limestone. Five species produced biomass in the order: Pennisetum sinese > Elsholtzia splendens > Vetiveria zizanioides > Setaria pumila > Sedum plumbizincicola. Over one growing season, the best accumulators for Cu and Cd were Pennisetum sinese and Sedum plumbizincicola, respectively. Overall, Pennisetum sinese was the best species for Cu and Cd removal when biomass was considered. However, Elsholtzia splendens soil had the highest enzyme activities and microbial populations, while the biological properties in Pennisetum sinese soil were moderately enhanced. Results would provide valuable insights for phytoremediation of metal-contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Behaviour of oxyfluorfen in soils amended with edaphic biostimulants/biofertilizers obtained from sewage sludge and chicken feathers. Effects on soil biological properties.

    Science.gov (United States)

    Rodríguez-Morgado, Bruno; Gómez, Isidoro; Parrado, Juan; Tejada, Manuel

    2014-09-01

    We studied the behaviour of oxyfluorfen herbicide at a rate of 4 l ha(-1) on biological properties of a Calcaric Regosol amended with two edaphic biostimulants/biofertilizers (SS, derived from sewage sludge; and CF, derived from chicken feathers). Oxyfluorfen was surface broadcast on 11 March 2013. Two days after application of oxyfluorfen to soil, both biostimulants/biofertilizers (BS) were also applied to the soil. An unamended soil without oxyfluorfen was used as control. For 2, 4, 7, 9, 20, 30, 60, 90 and 120 days of the application of herbicide to the soil and for each treatment, the soil dehydrogenase, urease, β-glucosidase and phosphatase activities were measured. For 2, 7, 30 and 120 days of the application of herbicide to the soil and for each treatment, soil microbial community was determined. The application of both BS to soil without the herbicide increased the enzymatic activities and soil biodiversity, mainly at 7 days of beginning the experiment. However, this stimulation was higher in the soil amended with SS than for CF. The application of herbicide in organic-amended soils decreased the inhibition of soil enzymatic activities and soil biodiversity. Possibly, the low-molecular-weight protein content easily assimilated by soil microorganisms is responsible for less inhibition of these soil biological properties.

  15. Biological Activity Assessment in Mexican Tropical Soils with Different Hydrocarbon Contamination Histories.

    Science.gov (United States)

    Riveroll-Larios, Jessica; Escalante-Espinosa, Erika; Fócil-Monterrubio, Reyna L; Díaz-Ramírez, Ildefonso J

    The use of soil health indicators linked to microbial activities, such as key enzymes and respirometric profiles, helps assess the natural attenuation potential of soils contaminated with hydrocarbons. In this study, the intrinsic physicochemical characteristics, biological activity and biodegradation potential were recorded for two soils with different contamination histories (>5 years and soil samples. Soil suspensions were tested as microbial inocula in biodegradation potential assays using contaminated perlite as an inert support. The basal respiratory rate of the recently contaminated soil was 15-38 mg C-CO 2  kg -1 h -1 , while the weathered soil presented a greater basal mineralisation capacity of 55-70 mg C-CO 2 kg -1 h -1 . The basal levels of lipase and dehydrogenase were significantly greater than those recorded in non-contaminated soils (551 ± 21 μg pNP g -1 ). Regarding the biodegradation potential assessment, the lipase (1000-3000 μg pNP g -1 of perlite) and dehydrogenase (~3000 μg INF g -1 of perlite) activities in the inoculum of the recently contaminated soil were greater than those recorded in the inoculum of the weathered soil. This was correlated with a high mineralisation rate (~30 mg C-CO 2 kg -1 h -1 ) in the recently contaminated soil and a reduction in hydrocarbon concentration (~30 %). The combination of an inert support and enzymatic and respirometric analyses made it possible to detect the different biodegradation capacities of the studied inocula and the natural attenuation potential of a recently contaminated soil at high hydrocarbon concentrations.

  16. Systematically biological prioritizing remediation sites based on datasets of biological investigations and heavy metals in soil

    Science.gov (United States)

    Lin, Wei-Chih; Lin, Yu-Pin; Anthony, Johnathen

    2015-04-01

    Heavy metal pollution has adverse effects on not only the focal invertebrate species of this study, such as reduction in pupa weight and increased larval mortality, but also on the higher trophic level organisms which feed on them, either directly or indirectly, through the process of biomagnification. Despite this, few studies regarding remediation prioritization take species distribution or biological conservation priorities into consideration. This study develops a novel approach for delineating sites which are both contaminated by any of 5 readily bioaccumulated heavy metal soil contaminants and are of high ecological importance for the highly mobile, low trophic level focal species. The conservation priority of each site was based on the projected distributions of 6 moth species simulated via the presence-only maximum entropy species distribution model followed by the subsequent application of a systematic conservation tool. In order to increase the number of available samples, we also integrated crowd-sourced data with professionally-collected data via a novel optimization procedure based on a simulated annealing algorithm. This integration procedure was important since while crowd-sourced data can drastically increase the number of data samples available to ecologists, still the quality or reliability of crowd-sourced data can be called into question, adding yet another source of uncertainty in projecting species distributions. The optimization method screens crowd-sourced data in terms of the environmental variables which correspond to professionally-collected data. The sample distribution data was derived from two different sources, including the EnjoyMoths project in Taiwan (crowd-sourced data) and the Global Biodiversity Information Facility (GBIF) ?eld data (professional data). The distributions of heavy metal concentrations were generated via 1000 iterations of a geostatistical co-simulation approach. The uncertainties in distributions of the heavy

  17. Biological indicators capable of assessing thermal treatment efficiency of hydrocarbon mixture-contaminated soil.

    Science.gov (United States)

    Wang, Jiangang; Zhan, Xinhua; Zhou, Lixiang; Lin, Yusuo

    2010-08-01

    In China, there are many special sites for recycling and washing the used drums, which release a variety of C5-C40 hydrocarbon mixture into the soil around the site. The remediation of these contaminated sites by thermal treatment is adopted ubiquitously and needs to be assessed. Here we report the feasibility of biological indicators applied to assess thermal treatment efficiency in such contaminated soil. A series of biological indicators, including seed germination index (SGI), root elongation index (REI), plant growth height, biomass, carbon dioxide evolved (CDE), soil respiration inhibition (SRI) and soil enzymatic activities, were employed to monitor or assess hydrocarbon mixture removal in thermal treated soil. The results showed that residual hydrocarbon mixture content correlated strongly negatively with SGI for sesamum (Sesamum indicum L.), plant height, and biomass for ryegrass (Lolium perenne L.) in the concentration ranges of 0-3990, 0-3170 and 0-2910 mg kg(-1), respectively. In contrast, REI for sesamum was positively correlated with residual hydrocarbon mixture content from 0 to 1860 mg kg(-1). In addition, both CDE and SRI demonstrated that 600 mg kg(-1) of residual hydrocarbon mixture content caused the highest amount of soil carbon dioxide emission and inhabitation of soil respiration. The results of soil enzymes indicated that 1000 mg kg(-1) of residual hydrocarbon mixture content was the threshold value of stimulating or inhibiting the activities of phosphatase and catalase, or completely destroying the activities of dehydrogenase, invertase, and urease. In conclusion, these biological indicators can be used as a meaningful complementation for traditional chemical content measurement in evaluating the environmental risk of the contaminated sites before and after thermal treatment. (c) 2010 Elsevier Ltd. All rights reserved.

  18. Application of Statistical Method of Path Analysis to Describe Soil Biological Indices

    Directory of Open Access Journals (Sweden)

    Y. Kooch

    2016-09-01

    Full Text Available Introduction: Among the collection of natural resources in the world, soil is considered as one of the most important components of the environment. Protect and improve the properties of this precious resource, requires a comprehensive and coordinated action that only through a deep understanding of quantitative (not only recognition of the quality the origin, distribution and functionality in a natural ecosystem is possible. Many researchers believe that due to the quick reactions of soil organisms to environmental changes, soil biological survey to estimate soil quality is more important than the chemical and physical properties. For this reason, in many studies the nitrogen mineralization and microbial respiration indices are regarded. The aim of the present study were to study the direct and indirect effects of soil physicochemical characteristics on the most important biological indicators (nitrogen mineralization and microbial respiration, which has not been carefully considered up to now. This research is the first study to provide evidence to the future planning and management of soil sciences. Materials and Methods: For this, a limitation of 20 ha area of Experimental Forest Station of Tarbiat Modares University was considered. Fifty five soil samples, from the top 15 cm of soil, were taken, from which bulk density, texture, organic C, total N, cation exchange capacity (CEC, nitrogen mineralization and microbial respiration were determined at the laboratory. The data stored in Excel as a database. To determine the relationship between biological indices and soil physicochemical characteristics, correlation analysis and factor analysis using principal component analysis (PCA were employed. To investigate all direct and indirect relationships between biological indices and different soil characteristics, path analysis (path analysis was used. Results and Discussion: Results showed significant positive relations between biological indices

  19. Biological oxygen demand in soils and hydrogel compositions for plant protection of the rhizosphere

    Science.gov (United States)

    Valentinovich Smagin, Andrey

    2018-02-01

    Potential biological activity of mineral and organogenic samples from light-textured sod-podzolic soils as well as of hydrogel compositions for protecting the root layer from pathogenic microflora and unfavorable edaphic factors were studied in laboratory conditions by oxygen consumption under the optimal hydrothermic conditions with portable gas analyzers. We have conducted ecological standardization of biological activity and organic matter destruction estimated by biological oxygen demand (BOD) in the widespread sandy soils. The primary outcome was the scale of gradations of biological oxygen uptake in soils with a range of quantities of potential biological activity from “very low” (140 g·m-3·hour-1), obtained on the basis of statistical processing of data array 1308 measurements. Acrylic polymer hydrogels had BOD = 0.2-2 g·m-3·hour-1, which corresponded to the periods of their half-lives from 0.2±0.1 to 6.8± 4.5 years, or relatively low resistance to biodestruction. In contrast to the pure gels, hydrogel compositions for rhizosphere based on ionic and colloidal silver showed low biological activity (BOD=0.01-0.2 g·m-3· hour-1) and, accordingly, significant resistance to biodegradation with half-lives from 5 to 70 years and above.

  20. Tree species traits influence soil physical, chemical, and biological properties in high elevation forests.

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    Edward Ayres

    Full Text Available BACKGROUND: Previous studies have shown that plants often have species-specific effects on soil properties. In high elevation forests in the Southern Rocky Mountains, North America, areas that are dominated by a single tree species are often adjacent to areas dominated by another tree species. Here, we assessed soil properties beneath adjacent stands of trembling aspen, lodgepole pine, and Engelmann spruce, which are dominant tree species in this region and are distributed widely in North America. We hypothesized that soil properties would differ among stands dominated by different tree species and expected that aspen stands would have higher soil temperatures due to their open structure, which, combined with higher quality litter, would result in increased soil respiration rates, nitrogen availability, and microbial biomass, and differences in soil faunal community composition. METHODOLOGY/PRINCIPAL FINDINGS: We assessed soil physical, chemical, and biological properties at four sites where stands of aspen, pine, and spruce occurred in close proximity to one-another in the San Juan Mountains, Colorado. Leaf litter quality differed among the tree species, with the highest nitrogen (N concentration and lowest lignin:N in aspen litter. Nitrogen concentration was similar in pine and spruce litter, but lignin:N was highest in pine litter. Soil temperature and moisture were highest in aspen stands, which, in combination with higher litter quality, probably contributed to faster soil respiration rates from stands of aspen. Soil carbon and N content, ammonium concentration, and microbial biomass did not differ among tree species, but nitrate concentration was highest in aspen soil and lowest in spruce soil. In addition, soil fungal, bacterial, and nematode community composition and rotifer, collembolan, and mesostigmatid mite abundance differed among the tree species, while the total abundance of nematodes, tardigrades, oribatid mites, and prostigmatid

  1. Prospects for biological soil-borne disease control: application of indigenous versus synthetic microbiomes

    Science.gov (United States)

    Biological disease control of soil-borne plant diseases has traditionally employed the biopesticide approach whereby single strains or strain mixtures are introduced into production systems through inundative/inoculative release. The approach has significant barriers that have long been recognized,...

  2. Evaluating the biological activity of oil-polluted soils using a complex index

    Science.gov (United States)

    Kabirov, R. R.; Kireeva, N. A.; Kabirov, T. R.; Dubovik, I. Ye.; Yakupova, A. B.; Safiullina, L. M.

    2012-02-01

    A complex index characterizing the biological activity of soils (BAS) is suggested. It is based on an estimate of the level of activity of catalase; the number of heterotrophic and hydrocarbon oxidizing microorganisms, microscopic fungi, algae, and cyanobacteria; and the degree of development of higher plants and insects in the studied soil. The data on using the BAS coefficient for evaluating the efficiency of rehabilitation measures for oil-polluted soils are given. Such measures included introducing the following biological preparations: Lenoil based on a natural consortium of microorganisms Bacillus brevis and Arthrobacter sp.; the Azolen biofertilizer with complex action based on Azotobacter vinelandii; the Belvitamil biopreparation, which is the active silt of pulp and paper production; and a ready-mixed industrial association of aerobic and anaerobic microorganisms that contains hydrocarbon oxidizing microorganisms of the Arthrobacter, Bacillus, Candida, Desulfovibrio, and Pseudomonas genera.

  3. Does the different mowing regime affect soil biological activity and floristic composition of thermophilous Pieniny meadow?

    Science.gov (United States)

    Józefowska, Agnieszka; Zaleski, Tomasz; Zarzycki, Jan

    2016-04-01

    The study area was located in the Pieniny National Park in the Carpathian Mountain (Southern Poland). About 30% of Park's area is covered by meadows. The climax stage of this area is forest. Therefore extensive use is indispensable action to keep semi-natural grassland such as termophilous Pieniny meadows, which are characterized by a very high biodiversity. The purpose of this research was to answer the question, how the different way of mowing: traditional scything (H), and mechanical mowing (M) or abandonment of mowing (N) effect on the biological activity of soil. Soil biological activity has been expressed by microbial and soil fauna activity. Microbial activity was described directly by count of microorganisms and indirectly by enzymatic activity (dehydrogenase - DHA) and the microbial biomass carbon content (MBC). Enchytraeidae and Lumbricidae were chosen as representatives of soil fauna. Density and species diversity of this Oligochaeta was determined. Samples were collected twice in June (before mowing) and in September (after mowing). Basic soil properties, such as pH value, organic carbon and nitrogen content, moisture and temperature, were determined. Mean count of vegetative bacteria forms, fungi and Actinobacteria was higher in H than M and N. Amount of bacteria connected with nitrification and denitrification process and Clostridium pasteurianum was the highest in soil where mowing was discontinued 11 years ago. The microbial activity measured indirectly by MBC and DHA indicated that the M had the highest activity. The soil biological activity in second term of sampling had generally higher activity than soil collected in June. That was probably connected with highest organic carbon content in soil resulting from mowing and the end of growing season. Higher earthworm density was in mowing soil (220 and 208 individuals m-2 in H and M respectively) compare to non-mowing one (77 ind. m-2). The density of Enchytraeidae was inversely, the higher density

  4. Long-term influence of liming on biological availability of radiocaesium in forest soils

    International Nuclear Information System (INIS)

    Konoplev, A.V.; Drissner, J.; Klemt, E.; Miller, R.; Zibold, G.; Konopleva, I.V.

    1998-01-01

    The results of research of 137 Cs transfer from soil to plants are presented for a spruce (Picea abies) forest plot in Baden-Wuerttemberg, Germany, 13 years after fertilization (83% CaCO 3 , 8% MgO, 6% K 2 O, 3% P 2 O 5 , 2.5 t/ha, 1984). Liming was found to result in a long-term decrease of the 137 Cs uptake by plants by a factor of 8-20 in comparison with the control plot. The results of liming include morphological changes of litter and characteristics of rooty soil layer: the parameters of caesium selective sorption and composition of a soil solution determining the biological availability of 137 Cs. The 137 Cs accumulation factors for forest plants were predicted based on a model of radiocaesium soil-to-plant transfer. The theoretical assessments are compared with experimental data

  5. BIOLOGICAL ACTIVITY OF SOILS OF ECOTONE COMMUNITIES’ TAMARISK THICKETS OF NORTHWEST CASPIAN

    Directory of Open Access Journals (Sweden)

    I. V. Yasulbutaeva

    2011-01-01

    Full Text Available In the article results of comparative estimation of soil biological activity indicators on the basis of studying intensity of vegetative organic and cellulose decomposition and also oxygen consumption in zone of shrubby thickets and open steppe of West Caspian are given. Rates of vegetative organic decomposition in soils of experience sites have made 5,23 and 5,67 mg·g-1·24 h-1 and didn't differ on sites. Intensity of cellulose decomposition in open site was above and has made 6,02 mg·g-1·24 h-1 against 4,16 mg·g-1·24 h-1 in soil of site with shrubby thickets. The estimation of intensity soil oxygen consumption hasn't shown an essential difference on sites.

  6. Investigation of biological destruction of benzo[a]pyrene andpolycyclic aromatic hydrocarbons of biochar in soil

    Science.gov (United States)

    Okunev, R. V.; Smirnova, E. V.; Sharipova, A. R.; Gilmutdinova, I. M.; Giniyatullin, K. G.

    2018-01-01

    The biological decomposition of benzo[a]pyrene in the concentrations exceeding the MAC (maximum permissible concentration) level in soils by 2, 5 and 10 times was studied in laboratory conditions. The gray forest soil samples were contaminated with benzo[a]pyrene and incubated in optimum for bacterial growth soil moisture for 30 and 60 days. The residual amount of contaminant was monitored by HPLC after extraction with acetone-cyclohexane (2:1). Soil microbial activity was evaluated by measuring basal respiration (BR) and substrate-induced respiration (SID) rates of the soil by gas chromatography. The results of the experiment showed that in 60 days the amount of benzo[a]pyrene in contaminated soils decreased; however, this time was not enough for complete decomposition of pollutant. In this case, benzo[a]pyrene has a negative effect on the BR and SIR rates. Soil contamination affected the BR rate only at high doses (10 MPC), whereas the SIR was a more sensitive indicator of the toxic effect of the pollutant and significantly reacts already at concentrations at the level of 2 MPC. The combination of PAHs isolated from biochar has a strong negative effect on the values of BR and SIR.

  7. Polycyclic aromatic hydrocarbons pollution effect on soil biological activity in the anthropogenic contaminated area

    Science.gov (United States)

    Batukaev, Abdulmalik; Sushkova, Svetlana; Minkina, Tatiana; Antonenko, Elena; Salamova, Anzhelika; Gimp, Alina; Deryabkina, Irina

    2017-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are one of the most significant environmental contaminants with mutagenic and carcinogenic properties to all living organisms. The changes in microbial community structure in technogenic polluted soil may be used as tools for predicting and monitoring natural degradation and for search the most effective and appropriate pathways of bioremediation. The present study is aimed to research the biological activity of the soil in the emission zone of Novocherkassk Power station (NPs) (Russia) polluted by PAHs in 2015. The NPs is one of the largest thermal power stations in the south of Russia burning low-quality coal appurtenant the enterprises of I hazardous class. Monitoring plots were located on virgin or no-till fallow areas and not subject to the sanitary-protection zone of the NPs. Soil samples were taken from a depth of 0- to 20-cm, because the major part of PAHs are accumulated in the surface soil layer. The soils of the plots mainly include Chernozems Calcic (plots 1, 4, 5, 7, 9 and 10), Phaeozems Haplic (plots 3, 6, 8 and 11) Fluvisols Umbric (plots 2 and 12). In the soil of 12 monitoring plots located around NPs there were determined the main enzymes, abundance of soil bacteria and 17 priority PAHs. PAHs extraction from soil was performed by new developed ecologically clean method of subcritical water extraction without organic solvents (Sushkova et al., 2015). The level of PAHs around NPs is high at the nearest to factory monitoring plots situated at distance 1,0-1,2 km and reaches from 1600,1±14,7 up to 373,6±7,1 mkg/kg in the 20-cm soil layer. Gradually decrease of PAHs contamination is observed while increasing the distance from the NPs. The level of highmolecular PAHs (4-6 aromatic rings) exceeds the level of lowmolecular (2-3 aromatic rings) PAHs in all monitoring plots situated though the prevailing wind direction from NPs. The close correlations were found between PAHs content and biological activity parameters

  8. Exposure to natural radiation from the earth's crust, atmosphere and outer space - the natural radioactivity of the earth's crust

    International Nuclear Information System (INIS)

    Schwab, R.G.

    1987-01-01

    Any conclusions to be drawn from the geochemical distribution pattern of radioactive elements for one's own conduct require to study their distribution in soil, earth crust, magmatic differentiation, rock disintegration zone and biosphere. The author notes that high activities in soils and rocks are contrasted by relatively low radiation dose levels absorbed by the human body. This is different for incorporated radiation. (DG) [de

  9. Soil quality evaluation following the implementation of permanent cover crops in semi-arid vineyards. Organic matter, physical and biological soil properties

    Energy Technology Data Exchange (ETDEWEB)

    Virto, I.; Imaz, M. J.; Fernandez-Ugalde, O.; Urrutia, I.; Enrique, A.; Bescansa, P.

    2012-07-01

    Changing from conventional vineyard soil management, which includes keeping bare soil through intense tilling and herbicides, to permanent grass cover (PGC) is controversial in semi-arid land because it has agronomic and environmental advantages but it can also induce negative changes in the soil physical status. The objectives of this work were (i) gaining knowledge on the effect of PGC on the soil physical and biological quality, and (ii) identifying the most suitable soil quality indicators for vineyard calcareous soils in semi-arid land. Key soil physical, organic and biological characteristics were determined in a Cambic Calcisol with different time under PGC (1 and 5 years), and in a conventionally managed control. Correlation analysis showed a direct positive relationship between greater aggregate stability (WSA), soil-available water capacity (AWC), microbial biomass and enzymatic activity in the topsoil under PGC. Total and labile organic C concentrations (SOC and POM-C) were also correlated to microbial parameters. Factor analysis of the studied soil attributes using principal component analysis (PCA) was done to identify the most sensitive soil quality indicators. Earthworm activity, AWC, WSA, SOC and POM-C were the soil attributes with greater loadings in the two factors determined by PCA, which means that these properties can be considered adequate soil quality indicators in this agrosystem. These results indicate that both soil physical and biological attributes are different under PGC than in conventionally-managed soils, and need therefore to be evaluated when assessing the consequences of PGC on vineyard soil quality. (Author) 65 refs.

  10. Soil biological attributes in arsenic-contaminated gold mining sites after revegetation.

    Science.gov (United States)

    Dos Santos, Jessé Valentim; de Melo Rangel, Wesley; Azarias Guimarães, Amanda; Duque Jaramillo, Paula Marcela; Rufini, Márcia; Marra, Leandro Marciano; Varón López, Maryeimy; Pereira da Silva, Michele Aparecida; Fonsêca Sousa Soares, Cláudio Roberto; de Souza Moreira, Fatima Maria

    2013-12-01

    Recovery of arsenic contaminated areas is a challenge society faces throughout the world. Revegetation associated with microbial activity can play an essential role in this process. This work investigated biological attributes in a gold mining area with different arsenic contents at different sites under two types of extant revegetation associated with cover layers of the soil: BS, Brachiaria sp. and Stizolobium sp., and LEGS, Acacia crassicarpa, A. holosericea, A. mangium, Sesbania virgata, Albizia lebbeck and Pseudosamanea guachapele. References were also evaluated, comprising the following three sites: B1, weathered sulfide substrate without revegetation; BM, barren material after gold extraction and PRNH (private reserve of natural heritage), an uncontaminated forest site near the mining area. The organic and microbial biomass carbon contents and substrate-induced respiration rates for these sites from highest to lowest were: PRNH > LEGS > BS > B1 and BM. These attributes were negatively correlated with soluble and total arsenic concentration in the soil. The sites that have undergone revegetation (LEGS and BS) had higher densities of bacteria, fungi, phosphate solubilizers and ammonium oxidizers than the sites without vegetation. Principal component analysis showed that the LEGS site grouped with PRNH, indicating that the use of leguminous species associated with an uncontaminated soil cover layer contributed to the improvement of the biological attributes. With the exception of acid phosphatase, all the biological attributes were indicators of soil recovery, particularly the following: microbial carbon, substrate-induced respiration, density of culturable bacteria, fungi and actinobacteria, phosphate solubilizers and metabolic quotient.

  11. Biological and chemical tests of contaminated soils to determine bioavailability and environmentally acceptable endpoints (EAE)

    International Nuclear Information System (INIS)

    Montgomery, C.R.; Menzie, C.A.; Pauwells, S.J.

    1995-01-01

    The understanding of the concept of bioavailability of soil contaminants to receptors and its use in supporting the development of EAE is growing but still incomplete. Nonetheless, there is increased awareness of the importance of such data to determine acceptable cleanup levels and achieve timely site closures. This presentation discusses a framework for biological and chemical testing of contaminated soils developed as part of a Gas Research Institute (GRI) project entitled ''Environmentally Acceptable Endpoints in Soil Using a Risk Based Approach to Contaminated Site Management Based on Bioavailability of Chemicals in Soil.'' The presentation reviews the GRI program, and summarizes the findings of the biological and chemical testing section published in the GRI report. The three primary components of the presentation are: (1) defining the concept of bioavailability within the existing risk assessment paradigm, (2) assessing the usefulness of the existing tests to measure bioavailability and test frameworks used to interpret these measurements, and (3) suggesting how a small selection of relevant tests could be incorporated into a flexible testing scheme for soils to address this issue

  12. Improvement of Soil Biology Characteristics at Paddy Field by System of Rice Intensification

    Directory of Open Access Journals (Sweden)

    Widyatmani Sih Dewi

    2015-07-01

    Full Text Available The aim of the research was to test the System of Rice Intensification (SRI method in improving the biological properties of paddy soil. The indicators of improvement were measured by the number of earthworm feces (cast, and the population of some microbial and nutrient content in the cast. The experiments were performed by comparing the three methods, namely: (1 SRI, (2 semi-conventional, and (3 conventional, using Randomized Completely Block Design. Each treatment was repeated nine times. The experiments were performed in the paddy fields belonging to farmers in Sukoharjo, Central Java. The result showed that the SRI (application of 1 tons ha-1 of vermicompost + 50% of inorganic fertilizer dosage tends to increase the number of earthworms cast. It is an indicator of earthworm activity in soil. Earthworms cast contains more phosphate solubilizing bacteria (12.98 x 1010cfu and N content (1.23% compared to its surrounding soil. There is a close functional relation between earthworms cast with total tiller number. SRI method is better than the other two methods to improve the biological characteristics of paddy soil that has the potential to maintain the sustainability of soil productivity.

  13. Impact of rice-straw biochars amended soil on the biological Si cycle in soil-plant ecosystem

    Science.gov (United States)

    Li, Zimin; Delvaux, Bruno; Struyf, Eric; Unzué-Belmonte, Dácil; Ronsse, Frederik; Cornelis, Jean-Thomas

    2017-04-01

    uptake by wheat , Si-/biochar does not increase the Si content of plants in either soil type. As expected, Si+/biochar and wollastonite significantly increase the Si content of wheat plants grown on both soils. The increase caused by Si+/biochar is, larger in NI (10 mg Si pot-1) than that in CA (5 mg Si pot-1). This result is in line with the release of CaCl2 extractable Si in both soils amended by Si+/biochar, confirming the validity of CaCl2-extraction to estimate the pool of bioavailable Si. Our data highlight that phytolith-rich biochar readily contributes to the pool of bioavailable Si, further taken up by plant roots, and increases Si mineralomass in plants as well as plant growth. Thus it provides an alternative to wollastonite application. The effect is particularly large in the highly weathered Nitisol. Under such conditions, the impact of phytolith rich biochar is not limited to the enhancement of Si biological cycle, but is extended to the increase of soil pH, CEC and organic matter content.

  14. Influence of red mud on soil microbial communities: Application and comprehensive evaluation of the Biolog EcoPlate approach as a tool in soil microbiological studies.

    Science.gov (United States)

    Feigl, Viktória; Ujaczki, Éva; Vaszita, Emese; Molnár, Mónika

    2017-10-01

    Red mud can be applied as soil ameliorant to acidic, sandy and micronutrient deficient soils. There are still knowledge gaps regarding the effects of red mud on the soil microbial community. The Biolog EcoPlate technique is a promising tool for community level physiological profiling. This study presents a detailed evaluation of Biolog EcoPlate data from two case studies. In experiment "A" red mud from Ajka (Hungary) was mixed into acidic sandy soil in soil microcosms at 5-50 w/w%. In experiement "B" red mud soil mixture was mixed into low quality subsoil in a field experiment at 5-50 w/w%. According to average well color development, substrate average well color development and substrate richness 5-20% red mud increased the microbial activity of the acidic sandy soil over the short term, but the effect did not last for 10months. Shannon diversity index showed that red mud at up to 20% did not change microbial diversity over the short term, but the diversity decreased by the 10th month. 30-50% red mud had deteriorating effect on the soil microflora. 5-20% red mud soil mixture in the low quality subsoil had a long lasting enhancing effect on the microbial community based on all Biolog EcoPlate parameters. However, 50% red mud soil mixture caused a decrease in diversity and substrate richness. With the Biolog EcoPlate we were able to monitor the changes of the microbial community in red mud affected soils and to assess the amount of red mud and red mud soil mixture applicable for soil treatment in these cases. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Impact of HydroPolymers on the soil biological components in mediterranean drylands

    Science.gov (United States)

    Dvořáčková, Helena; Hueso González, Paloma; Záhora, Jaroslav; Mikajlo, Irina; Damián Ruiz Sinoga, Jose

    2016-04-01

    Soil degradation affects more than 52 million ha of land in counties of the European Union. This problem is particularly serious in Mediterranean areas, where the effects of anthropogenic activities (tillage on slopes, deforestation, and pasture production) add to problems caused by prolonged periods of drought and intense and irregular rainfall. Soil microbiota can be used as an indicator of the soil healthy in degraded areas. This is because soil microbiota participates in the cycle elements and in the organic matter decomposition. All this helps to the young plants establishment and in long term protect the soils against the erosion. During dry periods in the Mediterranean areas, the lack of water entering the soil matrix leads to a loss of soil microbiological activity and it turns into a lower soil production capabilities. Under these conditions, the aim of this study was to evaluate the positive effect on soil biological components produced by an hydro absorbent polymer (Terracottem). The aim of the experiment was to evaluate the impact assessment of an hydropolymer (Terracottem) on the soil biological components. An experimental flowerpot layout was established in June 2015 and 12 variants with different amount of Terracottem were applied as follow: i) 3.0 kg.m3 ; ii) 1.5 kg.m3 and; iii) 0 kg.m3. In all the variants were tested the further additives: a) 1% of glucose, b) 50 kg N.ha-1 of Mineral nitrogen, c) 1% of Glucose + 50 kg N.ha-1 of Mineral nitrogen d) control (no additive). According to natural conditions, humidity have been kept at 15% in all the variants. During four weeks, mineral nitrogen leaching and soil respiration have been measured in each flowerplot. Respiration has been quantified four times every time while moistening containers and alkaline soda lime has been used as a sorbent. The amount of CO2 increase has been measured with the sorbent. Leaching of mineral nitrogen has been quantified by ion exchange resins (IER). IER pouches have been

  16. Integrating biological indicators in a Soil Monitoring Network (SMN to improve soil quality diagnosis - a case study in Southern Belgium (Wallonia

    Directory of Open Access Journals (Sweden)

    Krüger, I.

    2017-01-01

    Full Text Available Description of the subject. Soil organisms and their activities are essential for soil ecosystem functioning and they can thus be used as pertinent indicators of soil quality. Recent efforts have been undertaken to include biological indicators of soil quality into regional/national monitoring networks. Objectives. The aim of this study was to provide a first dataset of six biological indicators and two eco-physiological quotients for two landscape units in Wallonia. These spatial units are characterized by homogeneous climate conditions, soil type, land-use and management (here, grasslands in the Ardennes, and croplands in the Loam Region. Method. Respiration potential, microbial biomass carbon and nitrogen, net nitrogen mineralization, metabolic potential of soil bacteria and earthworm abundance were measured at a total of 60 sites in two different landscape units (LSU. Variability within each LSU was studied. Data was synthesized through calculation of a comprehensive score and presentation as radar plots. Results. All selected biological indicators were significantly higher under grassland than under cropland soils, highlighting the biological indicators' power of discrimination between main land use types. Variability within LSU depended on the biological indicator and was generally higher in grassland than in cropland soils. Each site could unambiguously be assigned to its landscape unit based on its calculated comprehensive score. Radar plots allowed an assessment of the distribution of values within a landscape unit at a glance. Conclusions. The pilot-study defined the first baseline values for agricultural soils in Wallonia and laid the foundation for a monitoring network of biological soil quality.

  17. The effects of biological soil conservation practices and community perception toward these practices in the Lemo District of Southern Ethiopia

    Directory of Open Access Journals (Sweden)

    Tamrat Sinore

    2018-06-01

    Full Text Available Land degradation is the critical ecological and agricultural challenges in Ethiopia. To combat this, the government and local farmers’ have undertaken soil and water conservation measures (physical, biological and integrated across the country since 1970's. This study investigate effect of elephant grass (P. purpureum and sesbania sesban (S. sesban used as biological land rehabilitation practices on soil properties and farmers’ perception on the practices. Composite soil samples (0–30 cm were randomly collected from lands treated with sesbania, elephant grass, and adjacent degraded grazing land, and a structured questionnaire was used to assess farmers’ perceptions. Statistical results showed that elephant grass and sesbania were significantly (P < .05 improves degraded land soil bulk density, pH, CEC, OC, TN, Av.P, K, Na, Ca, Mg and clay characteristics. Moreover, there was a significant (P < .05 difference between farmers’ perception of the effectiveness of physical, biological and integration of the two practices to control soil erosion. 48% of the farmers perceived that using both biological methods and the integration of biological with physical structures was more successful for controlling erosion and improving soil fertility. Logistic regression analysis revealed strong association (R2 = 0.84 between farmers’ perception on elephant grass and sesbanias' roles in soil conservation and groups of explanatory variables. Among the variables age, education and extension service significantly (P < .05 influenced farmers’ perception on the practices. Generally, elephant grass and sesbania are effective biological practices for rehabilitating lands and improving soil properties through minimizing erosion. Keywords: Soil erosion, Soil and water conservation, Biological soil conservation, Sesbania, Elephant grass

  18. Using cereal rye (catch crop) and dehydrogenase activity as indicators of the residual fertility effects of anaerobic soil disinfestation and other biological soil management practices following field tomato production

    Science.gov (United States)

    Anaerobic soil disinfestation (ASD) and other biological soil management practices employing carbon-rich and/or biologically-active ingredients help contribute to overall soil suppressiveness in crop disease management. However, their roles in soil fertility tended to be overshadowed by disease cont...

  19. INFLUENCE OF BIOLOGICAL AND THERMAL TRANSFORMED SEWAGE SLUDGE APPLICATION ON MANGANESE CONTENT IN PLANTS AND SOIL

    Directory of Open Access Journals (Sweden)

    Małgorzata Koncewicz-Baran

    2014-10-01

    Full Text Available A great variety of sewage sludge treatment methods, due to the agent (chemical, biological, thermal leads to the formation of varying ‘products’ properties, including the content of heavy metals forms. The aim of the study was to determine the effects of biologically and thermally transformed sewage sludge on the manganese content in plants and form of this element in the soil. The study was based on a two-year pot experiment. In this study was used stabilized sewage sludge collected from Wastewater Treatment Plant Krakow – ”Płaszów” and its mixtures with wheat straw in the gravimetric ratio 1:1 in conversion to material dry matter, transformed biologically (composting by 117 days in a bioreactor and thermally (in the furnace chamber with no air access by the following procedure exposed to temperatures of 130 °C for 40 min → 200 °C for 30 min. In both years of the study biologically and thermally transformed mixtures of sewage sludge with wheat straw demonstrated similar impact on the amount of biomass plants to the pig manure. Bigger amounts of manganese were assessed in oat biomass than in spring rape biomass. The applied sewage sludge and its biologically and thermally converted mixtures did not significantly affect manganese content in plant biomass in comparison with the farmyard manure. The applied fertilization did not modify the values of translocation and bioaccumulation ratios of manganese in the above-ground parts and roots of spring rape and oat. No increase in the content of the available to plants forms of manganese in the soil after applying biologically and thermally transformed sewage sludge mixtures with straw was detected. In the second year, lower contents of these manganese forms were noted in the soil of all objects compared with the first year of the experiment.

  20. Soil Surface Sealing Reverse or Promote Desertification?

    Science.gov (United States)

    Assouline, S.; Thompson, S. E.; Chen, L.; Svoray, T.; Sela, S.; Katul, G. G.

    2017-12-01

    Vegetation cover in dry regions is a key variable determining desertification. Bare soils exposed to rainfall by desertification can form physical crusts that reduce infiltration, exacerbating water stress on the remaining vegetation. Paradoxically, field studies show that crust removal is associated with plant mortality in desert systems, while artificial biological crusts can improve plant regeneration. Here, it is shown how physical crusts can act as either drivers of, or buffers against desertification depending on their environmental context. The behavior of crusts is first explored using a simplified theory for water movement on a uniform, partly vegetated slope subject to stationary hydrologic conditions. Numerical model runs supplemented with field data from a semiarid Long-Term Ecological Research (LTER) site are then applied to represent more realistic environmental conditions. When vegetation cover is significant, crusts can drive desertification, but this process is potentially self-limiting. For low vegetation cover, crusts mitigate against desertification by providing water subsidy to plant communities through a runoff-runon mechanism.

  1. Biological 12C-13C fractionation increases with increasing community-complexity in soil microcosms

    DEFF Research Database (Denmark)

    Yang, Weijun; Magid, Jakob; Christensen, Søren

    2014-01-01

    -rates and determine the trophic level of organisms in biological systems. While it is widely accepted that 15N-accumulates in natural food-chains, it is disputed to which extent this is the case for C-13. We constructed sand-microcosms inoculated with a dilution series of soil organisms and amended with glucose......Isotope fractionation is a ubiquitous phenomenon in natural ecosystems. When chemical elements move through food chains, natural isotope ratios change because biological processes tend to discriminate against heavier isotopes. This effect can be used to trace flows of matter, estimate process...

  2. Investigations involving oxidation-reduction (REDOX) pretreatment in conjunction with biological remediation of contaminated soils

    International Nuclear Information System (INIS)

    Montemagno, C.D.; Peters, R.W.; Tyree, A.

    1991-01-01

    Oxidation-reduction (REDOX) reactions are among the most important reactions involved in the environmental engineering field. Oxidation is a reaction in which the oxidation state of the treated compound is increased, i.e., the material loses electrons. Reduction involves the addition of a chemical (reducing) agent which lowers the oxidation state of a substance, i.e., the material gains electrons. Both processes of oxidation and reduction occur together. All REDOX reactions are thermodynamically based. There are a number of oxidizing agents which have been reported in the technical literature for treatment of refractory organic compounds. Common oxidizing agents include: hydrogen peroxide, ozone, ultraviolet (UV) irradiation, and combinations thereof, such as UV/ozone and UV/peroxide. A gradient of REDOX reactions is possible, depending on such factors as the oxidation-reduction reaction conditions, the availability of electron donors and acceptors, and the nature of the organic compounds involved. A review of the technical literature revealed that the majority of the oxidation-reduction applications have been in the areas of wastewater treatment and groundwater remediation, with very little attention devoted to the potential of using REDOX technologies for remediation of hydrocarbon contaminated soils. In this particular study, feasibility studies were performed on gasoline- contaminated soil. These studies focused on three major phases: 1) containment of the contamination by addition of tailoring agents to the soil, 2) biological remediation either performed in situ or on-site (using a slurry reactor system), and 3) pretreatment of the contaminated soils using REDOX systems, prior to biological remediation. This particular paper focuses on the third phase of the project, aimed at ''softening'' the refractory organics resulting in the formation of organic compounds which are more amenable to biological degradation. This paper focuses its attention on the use of

  3. Investigations involving oxidation-reduction (REDOX) pretreatment in conjunction with biological remediation of contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Montemagno, C. D. [Argonne National Laboratory, Argonne, IL (United States); Peters, R. W.; Tyree, A.

    1991-07-01

    Oxidation-reduction (REDOX) reactions are among the most important reactions involved in the environmental engineering field. Oxidation is a reaction in which the oxidation state of the treated compound is increased, i.e., the material loses electrons. Reduction involves the addition of a chemical (reducing) agent which lowers the oxidation state of a substance, i.e., the material gains electrons. Both processes of oxidation and reduction occur together. All REDOX reactions are thermodynamically based. There are a number of oxidizing agents which have been reported in the technical literature for treatment of refractory organic compounds. Common oxidizing agents include: hydrogen peroxide, ozone, ultraviolet (UV) irradiation, and combinations thereof, such as UV/ozone and UV/peroxide. A gradient of REDOX reactions is possible, depending on such factors as the oxidation-reduction reaction conditions, the availability of electron donors and acceptors, and the nature of the organic compounds involved. A review of the technical literature revealed that the majority of the oxidation-reduction applications have been in the areas of wastewater treatment and groundwater remediation, with very little attention devoted to the potential of using REDOX technologies for remediation of hydrocarbon contaminated soils. In this particular study, feasibility studies were performed on gasoline- contaminated soil. These studies focused on three major phases: 1) containment of the contamination by addition of tailoring agents to the soil, 2) biological remediation either performed in situ or on-site (using a slurry reactor system), and 3) pretreatment of the contaminated soils using REDOX systems, prior to biological remediation. This particular paper focuses on the third phase of the project, aimed at ''softening'' the refractory organics resulting in the formation of organic compounds which are more amenable to biological degradation. This paper focuses its attention on the use of

  4. Microbial diversity and structure are drivers of the biological barrier effect against Listeria monocytogenes in soil.

    Science.gov (United States)

    Vivant, Anne-Laure; Garmyn, Dominique; Maron, Pierre-Alain; Nowak, Virginie; Piveteau, Pascal

    2013-01-01

    Understanding the ecology of pathogenic organisms is important in order to monitor their transmission in the environment and the related health hazards. We investigated the relationship between soil microbial diversity and the barrier effect against Listeria monocytogenes invasion. By using a dilution-to-extinction approach, we analysed the consequence of eroding microbial diversity on L. monocytogenes population dynamics under standardised conditions of abiotic parameters and microbial abundance in soil microcosms. We demonstrated that highly diverse soil microbial communities act as a biological barrier against L. monocytogenes invasion and that phylogenetic composition of the community also has to be considered. This suggests that erosion of diversity may have damaging effects regarding circulation of pathogenic microorganisms in the environment.

  5. Biological permeable reactive barriers coupled with electrokinetic soil flushing for the treatment of diesel-polluted clay soil.

    Science.gov (United States)

    Mena, Esperanza; Ruiz, Clara; Villaseñor, José; Rodrigo, Manuel A; Cañizares, Pablo

    2015-01-01

    Removal of diesel from spiked kaolin has been studied in the laboratory using coupled electrokinetic soil flushing (EKSF) and bioremediation through an innovative biological permeable reactive barriers (Bio-PRBs) positioned between electrode wells. The results show that this technology is efficient in the removal of pollutants and allows the soil to maintain the appropriate conditions for microorganism growth in terms of pH, temperature, and nutrients. At the same time, EKSF was demonstrated to be a very interesting technology for transporting pollutants, microorganisms and nutrients, although results indicate that careful management is necessary to avoid the depletion of nutrients, which are effectively transported by electro-migration. After two weeks of operation, 30% of pollutants are removed and energy consumption is under 70 kWh m(-3). Main fluxes (electroosmosis and evaporation) and changes in the most relevant parameters (nutrients, diesel, microorganisms, surfactants, moisture conductivity and pH) during treatment and in a complete post-study analysis are studied to give a comprehensive description of the most relevant processes occurring in the soil (pollutant transport and biodegradation). Copyright © 2014 Elsevier B.V. All rights reserved.

  6. The validation of forensic DNA extraction systems to utilize soil contaminated biological evidence.

    Science.gov (United States)

    Kasu, Mohaimin; Shires, Karen

    2015-07-01

    The production of full DNA profiles from biological evidence found in soil has a high failure rate due largely to the inhibitory substance humic acid (HA). Abundant in various natural soils, HA co-extracts with DNA during extraction and inhibits DNA profiling by binding to the molecular components of the genotyping assay. To successfully utilize traces of soil contaminated evidence, such as that found at many murder and rape crime scenes in South Africa, a reliable HA removal extraction system would often be selected based on previous validation studies. However, for many standard forensic DNA extraction systems, peer-reviewed publications detailing the efficacy on soil evidence is either lacking or is incomplete. Consequently, these sample types are often not collected or fail to yield suitable DNA material due to the use of unsuitable methodology. The aim of this study was to validate the common forensic DNA collection and extraction systems used in South Africa, namely DNA IQ, FTA elute and Nucleosave for processing blood and saliva contaminated with HA. A forensic appropriate volume of biological evidence was spiked with HA (0, 0.5, 1.5 and 2.5 mg/ml) and processed through each extraction protocol for the evaluation of HA removal using QPCR and STR-genotyping. The DNA IQ magnetic bead system effectively removed HA from highly contaminated blood and saliva, and generated consistently acceptable STR profiles from both artificially spiked samples and crude soil samples. This system is highly recommended for use on soil-contaminated evidence over the cellulose card-based systems currently being preferentially used for DNA sample collection. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Bioremediation of oil contaminated soil from service stations. Evaluation of biological treatment

    International Nuclear Information System (INIS)

    Puustinen, J.; Jorgensen, K.S.; Strandberg, T.; Suortti, A.M.

    1995-01-01

    Biological treatment of contaminated soil has received much attention during the last decade. Microbes are known to be able to degrade many oil hydrocarbons. However, research is needed to ensure that new technologies are implemented in a safe and reliable way under Finnish climatic conditions. The main points of interest are the rate of the degradation as well as the survival and efficiency of microbial inoculants possibly introduced during the treatment. During 1993 the biotreatability of oil-contaminated soil from service stations was investigated in cooperation with the Finnish Petroleum Federation. The goal of this field-scale study was to test how fast lubrication oil can be composted during one Finnish summer season and to find out whether microbial inoculants would enhance the degradation rate. The soil was excavated from three different service stations in the Helsinki metropolitan area and was transported to a controlled composting area. The soil was sieved and compost piles, also called biopiles, were constructed on the site. Bark chips were used as the bulking agent and nutrients and lime were added to enhance the biological activity. Two different commercial bacterial inoculants were added to two of the piles. The piles were turned by a tractor-drawn screw-type mixer at two to four weeks interval. Between the mixings, the piles were covered with tarpaulins to prevent evaporation and potential excessive wetting. Several microbiological parameters were determined during the test period as well as the temperature and mineral oil content

  8. Chemical properties of soils treated with biological sludge from gelatin industry

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Melo Guimarães

    2012-04-01

    Full Text Available The impact of agro-industrial organic wastes in the environment can be reduced when used in agriculture. From the standpoint of soil fertility, residue applications can increase the organic matter content and provide nutrients for plants. This study evaluated the effect of biological sludge from gelatin industry on the chemical properties of two Ultisols (loamy sand and sandy clay and an Oxisol (clay. The experiment lasted 120 days and was carried out in laboratory in a completely randomized design with factorial arrangement, combining the three soils and six biological sludge rates (0, 100, 200, 300, 400, and 500 m³ ha-1, with three replications. Biological sludge rates of up to 500 m³ ha-1 decreased soil acidity and increased the effective cation exchange capacity (CEC and N, Ca, Mg, and P availability, without exceeding the tolerance limit for Na. The increase in exchangeable base content, greater than the effective CEC, indicates that the major part of cations added by the sludge remains in solution and can be lost by leaching.

  9. The Impact of Olive Mill Wastewater on the Physicochemical and Biological Properties of Soils in Northwest Jordan

    Directory of Open Access Journals (Sweden)

    Mohammad Wahsha

    2014-12-01

    Full Text Available Soil contamination may influence negatively soil health, which often limits and sometimes disqualifies soil biodiversity and decreases plant growth. Soil health is the continued capacity of the soil to function as a vital living system, providing essential ecosystem services. Within soils, all bio-geo-chemical processes of the different ecosystem components are combined. These processes are able to sustain biological productivity of soil, to maintain the quality of surrounding air and water environments, as well as to promote plant, animal, and human health. A common criterion to evaluate long term sustainability of ecosystems is to assess the quality of soil. However, the increased concentration and distribution of toxic substances in soils by mismanagement of industrial activities, overuse of agrochemicals and waste disposal are causing worldwide concern. A major environmental concern in the Mediterranean countries is the production of the large quantities of olive oil mill wastewater (OMW produced during olive oil extraction process. OMW inhibits several groups of bacteria and fungal species, thus affecting soil stability. In the present study, we investigated the effect of OMW on the soil physical, chemical characteristics and the microarthropods structure. All soil samples were collected from an olive mill garden in Northwest Jordan. Biological soil quality index (QBS-ar values appeared to decrease with respect to soil pollution by OMW. All investigated parameters were significantly different depending on the levels of OMW contamination in soil. Anthropogenic activities influenced the microarthropod community, altering both quantity and quality of soil chemical and physical structure of the microhabitats. Preliminary data obtained in this study suggest that the application of QBS-ar index could be a useful tool for evaluating surface soils health status.

  10. The Role of Soil Biological Function in Regulating Agroecosystem Services and Sustainability in the Quesungual Agroforestry System

    Science.gov (United States)

    Fonte, S.; Pauli, N.; Rousseau, L.; SIX, J. W. U. A.; Barrios, E.

    2014-12-01

    The Quesungual agroforestry system from western Honduras has been increasingly promoted as a promising alternative to traditional slash-and-burn agriculture in tropical dry forest regions of the Americas. Improved residue management and the lack of burning in this system can greatly impact soil biological functioning and a number of key soil-based ecosystem services, yet our understanding of these processes has not been thoroughly integrated to understand system functionality as a whole that can guide improved management. To address this gap, we present a synthesis of various field studies conducted in Central America aimed at: 1) quantifying the influence of the Quesungual agroforestry practices on soil macrofauna abundance and diversity, and 2) understanding how these organisms influence key soil-based ecosystem services that ultimately drive the success of this system. A first set of studies examined the impact of agroecosystem management on soil macrofauna populations, soil fertility and key soil processes. Results suggest that residue inputs (derived from tree biomass pruning), a lack of burning, and high tree densities, lead to conditions that support abundant, diverse soil macrofauna communities under agroforestry, with soil organic carbon content comparable to adjacent forest. Additionally, there is great potential in working with farmers to develop refined soil quality indicators for improved land management. A second line of research explored interactions between residue management and earthworms in the regulation of soil-based ecosystem services. Earthworms are the most prominent ecosystem engineers in these soils. We found that earthworms are key drivers of soil structure maintenance and the stabilization of soil organic matter within soil aggregates, and also had notable impacts on soil nutrient dynamics. However, the impact of earthworms appears to depend on residue management practices, thus indicating the need for an integrated approach for

  11. The time-dependent effect of the biological component of 137Cs soil contamination

    International Nuclear Information System (INIS)

    Dederichs, H.; Pillath, J.; Lennartz, R.; Hill, P.; Hille, R.

    2004-01-01

    In investigations of the long-term development of the population dose in the highly contaminated regions of the Commonwealth of Independence States it was found that the external dose has not decreased as strongly as expected since 1992. Further investigations have shown that, contrary to expectations, no linear correlation can be observed between soil contamination and measured area dose rate. As a contribution towards clarifying these issues, the area dose rate and the soil contamination including the plant fraction were investigated in the Korma district, Belarus. It was found that it is necessary to cover and average over larger areas in order to determine from ground contamination the long-term development of the external dose commitment. This means that for this purpose the introduction of an ''effective'' surface contamination (sum of mineral and organic contamination components) is necessary. The phenomena observed are described in a model, which permits an analytical calculation of the contamination profile in soil taking migration and transfer effects into account. The differences observed between the measured soil contamination and the resulting external doses or the directly measured dose rate can be explained by the proposed model. Moreover, their long-term development can be calculated. The results show that a time decade after the accident the biological part of the ''effective'' soil contamination becomes dominant and cannot be neglected. (orig.)

  12. Application of a biological process for decontamination of soils in the far north

    International Nuclear Information System (INIS)

    Pouliot, Y.; Sansregret, J.-L.

    1994-01-01

    The site of a diesel-fuelled power station in the extreme north of Quebec (62 degree latitude) was contaminated with hydrocarbons. The site was characterized by typical Arctic conditions: presence of permafrost, limited land transport facilities, restricted availability of machinery and equipment, and scarcity of skilled labor and specialized services. To remediate the site, it was decided to excavate the contaminated soil and subject it to a biological treatment process. The soil was piled on an impermeable base inside of the old power station building and the following parameters were controlled in order to optimize the biodegradation of the hydrocarbons: temperature, humidity, pH, presence of hydrocarbon degrading microorganisms, and concentrations of oxygen, nitrogen, and phosphorus in the soil. Samples were analyzed to monitor the performance of the biodegradation process. In less than 12 weeks, of treatment, an inital hydrocarbon content estimated at 6,400 mg/kg of oils and greases was reduced to 750 mg/kg, corresponding to a level acceptable for residential areas. Indigenous microorganisms capable of degrading hydrocarbons were already present in the native soil in sufficient quantity, and their performance improved when the soil conditions were optimized. 1 fig., 3 tabs

  13. Chelating impact assessment of biological ad chemical chelates on metal extraction from contaminated soils

    International Nuclear Information System (INIS)

    Manwar, S.; Iram, S.

    2014-01-01

    Soil contamination is the result of uncontrolled waste dumping and poor practices by humans. Of all the pollutants heavy metals are of particular concern due to their atmospheric deposition, leaching capacity and non-biodegradability. Heavy metal containing effluent is discharged into the agricultural fields and water bodies. This results in the accumulation of heavy metals in soil and the crops grown on that soil. Studies have revealed detrimental impacts on soil fertility and the poor health of animals and humans. Phytoextraction is widely researched for remediation of heavy metal contaminated soil. To enhance the effect of phytoextraction heavy metals have to be available to the plants in soluble form. In this study the potential of different chelating agents was assessed in solubilizing the heavy metals making easy for plants to uptake them. For this purpose efficient chemical and biological chelating agent had to be identified. Along with that an optimum dose and application time for chemical chelating agent was determined. Ethylenediamine tetraacetic acid (EDTA), Diethylene triamine pentaacetic acid (DTPA), Nitriloacetic acid (NTA) were applied to the soil, containing Pb, Cr, Cu and Cd, at different concentrations and application time. Aspergillus niger and Aspergillus flavus were incubated in soil for different time periods. In correspondence with findings of the study, Pb and Cr were best solubilized by 5mM EDTA. For Cd and Cu 5mM DTPA carried out efficient chelation. NTA showed relatively inadequate solubilisation, although for Cr it performed equal to EDTA. A. niger and A. flavus instead of solubilizing adsorbed the metals in their biomass. Adsorption was mainly carried out by A. niger. (author)

  14. Assessing the Soil Physiological Potential Using Pedo-Biological Diagnosis Under Minimum-Tillage System and Mineral Fertilization

    Directory of Open Access Journals (Sweden)

    Lazar Bireescu

    2014-11-01

    Full Text Available The main objective of sustainable agriculture is the protection of environment and natural vegetal and soil resources. Accordingly, the objective of this research was to assess the impact of technological systems by minimum tillage on soil biological activity, using the Pedo-Biological Diagnosis of Soil Resources. Our research was conducted on haplic chernozem from Experimental Station of UASVM of Iasi, Romania, during the seasonal dynamic, to the soybean crop, on unfertilized and fertilized agrofond, using moderate mineral doses (N80P80 as average of 2009–2010 period, under minimum tillage (2x disk, paraplow, chisel compared to conventional (plugging at 20 cm and 30 cm. In the case of soil works with chisel and paraplow without return of furrow, the Pedo-Biological Diagnosis highlights an increase of soil physiological potential, in the both variants (unfertilized and fertilized, unlike the method of alternating the depth of plugging that proved to be ineffective.

  15. Isolasi Dan Identifikasi Pseudomonas Dari Tanah Kebun Biologi Wamena Dan Uji Awal Sebagai Agen Biokontrol Fusarium*[the Isolation and Identification of Pseudomonas From the Wamena Biological Gardens Soil and Its Preliminary Test as Biocontrol Agent on Fusari

    OpenAIRE

    Latupapua, HJD; Nurhidayat, N

    2003-01-01

    Pseudomonas bacteria plays essential role in soil ecology such as decomposer and biological control. The bacteria were isolated on selective media and identified from five soil samples taken within area of Wamena Biological Gardens.There are six species Pseudomonas were indentified based on morphological characters and biochemical reaction.P. striata was found to be common in soil of the area.No pathogen Pseudomonas was indentified in all soil samples. Preliminary study on biological control ...

  16. Biological properties of soils of former forest fires in Samosir Regency of North Sumatera

    Directory of Open Access Journals (Sweden)

    D. Elfiati

    2016-04-01

    Full Text Available A study that was aimed to identify the impact of forest fires on the biological properties of soils was carried out at former forest fire areas in Samosir Regency of North Sumatera. Soil samples were collected from former forest fire areas of 2014, 2013, 2012, 2011, 2010. The composite soil samples were collected systematically using diagonal method as much as 5 points in each period of fire. The soil samples were taken at three plots measuring 20 x 20 m 0-20 cm depth. Soil biological properties observed were soil organic C content, total number of microbes, abundance of arbuscular mycorrhizal fungi, phosphate solubilizing microbes, and soil microbial activity. The results showed that organic C content ranged from 0.75 to 2.47% which included criteria for very low to moderate. Arbuscular mycorrhizal fungi spores were found belonging to the genus of Glomus and Acaulospora. Spore number increased with the fire period ranging from 45 spores (forest fire in 2014 to 152 spores (forest fire in 2010. The total number of microbes obtained ranged from 53.78 x 107 cfu/mL (forest fire in 2010 to 89.70 x107 cfu/mL (forest fire in 2013. It was found 29 isolates of phosphate solubilizing microbes that consisted of 14 bacterial isolates and 15 fungi isolates with densities ranging from 27.642 x105 cfu/mL (forest fires in 2014 to 97.776 x 105 cfu/ mL (forest fires in 2011. The isolates of phosphate solubilizing bacteria identified consisted of Pseudomonas, Flavobacterium, Staphylococcus, and Mycobacterium genus, whereas the isolates of phosphate solubilizing fungi obtained consisted of Aspergillus and Penicillium genus. Soil respiration ranged from 2.14 kg / day (forest fire in 2010 up to 3.71 kg / day (forest fire in 2013. The varied results were greatly influenced by the type or form of the fires and intensity of fires. In the study area the type or form of the fires were canopy fires with low intensity.

  17. Short term recovery of soil biological functions in a new vineyard cultivated in organic farming

    Science.gov (United States)

    Costantini, Edoardo; Agnelli, Alessandro; Fabiani, Arturo; Gagnarli, Elena; Mocali, Stefano; Priori, Simone; Simoni, Sauro; Valboa, Giuseppe

    2014-05-01

    soil biological classes). Physical soil characteristics remained unchanged after the first year from the earthworks and did not change under grass cover. Chemical analysis only indicated a significant effect of earthworks. Over the 2010-2013 period, the new vineyard showed a slight increase of TOC and total N contents; as compared to the old vineyard, it averaged lower TOC and total N, and higher CaCO3 contents, suggesting still evolving equilibrium conditions. Microarthropod analysis showed significant different abundances and communities' structures both by management system and by year, increasing where the land use pressure was reduced by permanent grass cover and along with the aging of vineyard. Though the euedaphic forms, well adapted to soil life, were always rare. Microbiological analysis showed a different structure of eubacterial communities and a lower microbial activity in the new vineyard, especially during 2010-2012. In contrast, significant differences were not observed between the two vineyards in 2013, and grass cover effect was controversial. To sum up, the consequence of deep earthworks on chemical and biological properties were still evident after four years from planting and more time was needed to recover soil functions. Permanent grass cover did not always show a consistent positive effect.

  18. Herbicide effect on 14C cellulose and 14C straw decomposition in soils. Influence of phenylcarbamates on biological activity

    International Nuclear Information System (INIS)

    Ramanujam, T.; Bellinck, Celine; Mayaudon, J.

    1979-01-01

    Aniline, 2,4-D, 2,4,5-T, simazine and paraquat have no effect on cellulose decomposition in soils. The monophenylcarbamates SN 38210, IPC and CIPC, applied at 500 ppm exert per contra an important inhibitory effect. The decomposition of straw is little influenced by the phenylcarbamates, 100 ppm of 2,4-D, 2,4,5-T or simazine significantly increase the decomposition of straw in a sandy soil. The diphenylcarbamate SN 38584 has little effect on biological activity of soils; this is strongly inhibited by application of 500 ppm of SN 38210. This inhibition may be reduced by amending the soil with lignin but addition of straw or cellulose doesn't enhance biological activity of soil. Addition of 5000 ppm of soil extract or humic acids reduces somewhat the toxicity of SN 38210 [fr

  19. Biological in situ treatment of soil contaminated with petroleum - Laboratory scale simulations

    International Nuclear Information System (INIS)

    Palvall, B.

    1997-06-01

    Laboratory scale simulations of biological in situ treatment of soil contaminated with petroleum compounds have been made in order to get a practical concept in the general case. The work was divided into seven distinct parts. Characterisation, leaching tests and introductory microbiological investigations were followed by experiments in suspended phases and in situ simulations of solid phase reactors. For the suspensions, ratios L/S 3/1 and shaking for a couple of hours were enough to detach organic compounds in colloid or dissolved form. When testing for a time of one month anaerobic environment and cold temperatures of 4 centigrade as well gave acceptable reductions of the actual pollution levels. The range of variation in the soil tests performed showed that at least triple samples are needed to get satisfactory statistical reliability. It was shown that adequate experimental controls demand very high concentrations of e.g. sodium azide when dealing with soil samples. For triple samples in suspended phase without inoculation the weight ratios of oxygen consumption/biological degradation of aliphatic compounds were 2.41 to 2.96. For the complex overall reduction no exact rate constants could be found. The reduction of hydrocarbons were in the interval 27 to 95 % in suspension tests. Solid phase simulations with maximum water saturation showed the highest degree of reduction of hydrocarbons when using dissolved peroxide of hydrogen as electron acceptor while the effect of an active sludge reactor in series was little - reductions of aliphatic compounds were between 21 and 33 % and of aromatic compounds between 32 and 65 %. The influence of different contents of water was greater than adding inoculum or shaking the soil at different intervals in the unsaturated cylinders. The starting level of hydrocarbons was 2400 mg/kg dry weight soil and the end analyses were made after 100 days. The reduction was between 32 and 80 %. 82 refs

  20. Physical, chemical, and biological properties of soil under soybean cultivation and at an adjacent rainforest in Amazonia

    Science.gov (United States)

    T.P. Beldini; R.C. Oliveira Junior; Michael Keller; P.B. de Camargo; P.M. Crill; A. Damasceno da Silva; D. Bentes dos Santos; D. Rocha de Oliveira

    2015-01-01

    Land-use change in the Amazon basin has occurred at an accelerated pace during the last decade, and it is important that the effects induced by these changes on soil properties are better understood. This study investigated the chemical, physical, and biological properties of soil in a field under cultivation of soy and rice, and at an adjacent primary rain forest....

  1. Physics of Neutron Star Crusts

    Directory of Open Access Journals (Sweden)

    Chamel Nicolas

    2008-12-01

    Full Text Available The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.

  2. Soil bacterial and fungal community responses to nitrogen addition across soil depth and microhabitat in an arid shrubland

    Science.gov (United States)

    Mueller, Rebecca C.; Belnap, Jayne; Kuske, Cheryl R.

    2015-01-01

    Arid shrublands are stressful environments, typified by alkaline soils low in organic matter, with biologically-limiting extremes in water availability, temperature, and UV radiation. The widely-spaced plants and interspace biological soil crusts in these regions provide soil nutrients in a localized fashion, creating a mosaic pattern of plant- or crust-associated microhabitats with distinct nutrient composition. With sporadic and limited rainfall, nutrients are primarily retained in the shallow surface soil, patterning biological activity. We examined soil bacterial and fungal community responses to simulated nitrogen (N) deposition in an arid Larrea tridentata-Ambrosia dumosa field experiment in southern Nevada, USA, using high-throughput sequencing of ribosomal RNA genes. To examine potential interactions among the N application, microhabitat and soil depth, we sampled soils associated with shrub canopies and interspace biological crusts at two soil depths (0–0.5 or 0–10 cm) across the N-amendment gradient (0, 7, and 15 kg ha−1 yr−1). We hypothesized that localized compositional differences in soil microbiota would constrain the impacts of N addition to a microhabitat distribution that would reflect highly localized geochemical conditions and microbial community composition. The richness and community composition of both bacterial and fungal communities differed significantly by microhabitat and with soil depth in each microhabitat. Only bacterial communities exhibited significant responses to the N addition. Community composition correlated with microhabitat and depth differences in soil geochemical features. Given the distinct roles of soil bacteria and fungi in major nutrient cycles, the resilience of fungi and sensitivity of bacteria to N amendments suggests that increased N input predicted for many arid ecosystems could shift nutrient cycling toward pathways driven primarily by fungal communities.

  3. Soil bacterial and fungal community responses to nitrogen addition across soil depths and microhabitat in an arid shrubland

    Directory of Open Access Journals (Sweden)

    Rebecca C Mueller

    2015-09-01

    Full Text Available Arid shrublands are stressful environments, typified by alkaline soils low in organic matter, with biologically-limiting extremes in water availability, temperature and UV radiation. The widely-spaced plants and interspace biological soil crusts in these regions provide soil nutrients in a localized fashion, creating a mosaic pattern of plant- or crust-associated microhabitats with distinct nutrient composition. With sporadic and limited rainfall, nutrients are primarily retained in the shallow surface soil, patterning biological activity. We examined soil bacterial and fungal community responses to simulated nitrogen (N deposition in an arid Larrea tridentata-Ambrosia dumosa field experiment in southern Nevada, USA, using high-throughput sequencing of ribosomal RNA genes. To examine potential interactions among the N application, microhabitat and soil depth, we sampled soils associated with shrub canopies and interspace biological crusts at two soil depths (0-0.5 cm or 0-10 cm across the N-amendment gradient (0, 7 and 15 kg ha-1 yr-1. We hypothesized that localized compositional differences in soil microbiota would constrain the impacts of N addition to a microhabitat distribution that would reflect highly localized geochemical conditions and microbial community composition. The richness and community composition of both bacterial and fungal communities differed significantly by microhabitat and with soil depth in each microhabitat. Only bacterial communities exhibited significant responses to the N addition. Community composition correlated with microhabitat and depth differences in soil geochemical features. Given the distinct roles of soil bacteria and fungi in major nutrient cycles, the resilience of fungi and sensitivity of bacteria to N amendments suggests that increased N input predicted for many arid ecosystems could shift nutrient cycling toward pathways driven primarily by fungal communities.

  4. Impact of reclamation treatment on the biological activity of soils of the solonetz complex in Western Siberia

    Science.gov (United States)

    Berezin, L. V.; Khamova, O. F.; Paderina, E. V.; Gindemit, A. M.

    2014-11-01

    The abundance and activity of the soil microflora were studied in a field experiment with the use of green manure crops to assess the impact of reclamation measures on the biological activity of soils of the solonetz complex. The number of microorganisms in the plow soil horizon increased in the background of the green fallows as compared to the black ones. Coefficients of mineralization, immobilization, and transformation of organic compounds were calculated for different variants of the soil treatment. The value of the mineralization coefficient indicates the intense decomposition of the green manure that entered the soil. In the first year, peas were actively decomposed, while oats, in the second year (aftereffect). The activity of the soil enzymes (invertase, urease, and catalase) was determined. A close relationship between the catalase activity and the intensity of the microbiological processes in the soils was revealed.

  5. Biological functioning of PAH-polluted and thermal desorption-treated soils assessed by fauna and microbial bioindicators.

    Science.gov (United States)

    Cébron, Aurélie; Cortet, Jérôme; Criquet, Stéven; Biaz, Asmaa; Calvert, Virgile; Caupert, Cécile; Pernin, Céline; Leyval, Corinne

    2011-11-01

    A large number of soil bioindicators were used to assess biological diversity and activity in soil polluted with polycyclic aromatic hydrocarbons (PAHs) and the same soil after thermal desorption (TD) treatment. Abundance and biodiversity of bacteria, fungi, protozoa, nematodes and microarthropods, as well as functional parameters such as enzymatic activities and soil respiration, were assessed during a two year period of in situ monitoring. We investigated the influence of vegetation (spontaneous vegetation and Medicago sativa) and TD treatment on biological functioning. Multivariate analysis was performed to analyze the whole data set. A principal response curve (PRC) technique was used to evaluate the different treatments (various vegetation and contaminated vs. TD soil) contrasted with control (bare) soil over time. Our results indicated the value of using a number of complementary bioindicators, describing both diversity and functions, to assess the influence of vegetation on soil and discriminate polluted from thermal desorption (TD)-treated soil. Plants had an influence on the abundance and activity of all organisms examined in our study, favoring the whole trophic chain development. However, although TD-treated soil had a high abundance and diversity of microorganisms and fauna, enzymatic activities were weak because of the strong physical and chemical modifications of this soil. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  6. Biological treatment processes for PCB contaminated soil at a site in Newfoundland

    International Nuclear Information System (INIS)

    Punt, M.; Cooper, D.; Velicogna, D.; Mohn, W.; Reimer, K.; Parsons, D.; Patel, T.; Daugulis, A.

    2002-01-01

    SAIC Canada is conducting a study under the direction of a joint research and development contract between Public Works and Government Services Canada and Environment Canada to examine the biological options for treating PCB contaminated soil found at a containment cell at a former U.S. Military Base near Stephenville, Newfoundland. In particular, the study examines the feasibility of using indigenous microbes for the degradation of PCBs. The first phase of the study involved the testing of the microbes in a bioreactor. The second phase, currently underway, involves a complete evaluation of possible microbes for PCB degradation. It also involves further study into the biological process options for the site. Suitable indigenous and non-indigenous microbes for PCB dechlorination and biphenyl degradation are being identified and evaluated. In addition, the effectiveness and economics of microbial treatment in a conventional bioreactor is being evaluated. The conventional bioreactor used in this study is the two-phase partitioning bioreactor (TPPB) using a biopile process. Results thus far will be used to help Public Works and Government Services Canada to choose the most appropriate remedial technology. Preliminary results suggest that the use of soil classification could reduce the volume of soil requiring treatment. The soil in the containment cell contains microorganisms that could grow in isolation on biphenyl, naphthalene and potentially Aroclor 1254. Isolated native microbes were inoculated in the TPPB for growth. The TPPB was also run successfully under anaerobic conditions. Future work will involve lab-scale evaluation of microbes for PCB dechlorination and biphenyl degradation using both indigenous and non-indigenous microbes. The next phase of study may also involve field-scale demonstration of treatment methods. 2 refs., 3 tabs., 5 figs

  7. Assessment of the biological and chemical availability of the freshly spiked and aged DDE in soil

    International Nuclear Information System (INIS)

    Škulcová, L.; Neuwirthová, N.; Hofman, J.; Bielská, L.

    2016-01-01

    The study compared the ability of various chemical methods (XAD, β-hydroxypropylcyclodextrin - HPCD) and solid phase micro-extraction (SPME)) to mimic earthworm uptake from two similar soils containing either spiked or aged p,p´-DDE, thus representing two extreme scenarios with regard to the length of pollutant-soil contact time and the way of contamination. The extent of bioaccumulation was assessed at fixed exposure periods (10 and 21 days) and at equilibrium derived from uptake curves by multiple-point comparison or kinetic modeling. The decision on the best chemical predictor of biological uptake differed. The degree of bioaccumulation at equilibrium was best predicted by XAD while HPCD rather reflected the extent of accumulation derived after 21 days when, however, steady-state was not reached for spiked p,p´-DDE. SPME seemed to underestimate the uptake of aged p,p´-DDE, probably of the fraction taken up via soil particles. Thus, the degree of predictability seems to be associated with the capability of the chemical method to mimic the complex earthworm uptake via skin and intestinal tract as well as with the quality of biological data where the insufficient length of exposure period appears to be the major concern. - Highlights: • The uptake kinetics of spiked and aged p,p´-DDE to earthworms/samplers was measured. • Three chemical methods were used to predict earthworm uptake. • Equilibrium was not reached within the OECD recommended 21 days for spiked p,p´-DDE. • SPME seems to underestimate the uptake of aged p,p´-DDE. • The best predictor of earthworm uptake seems to be the XAD method. - Capsule: The poor prediction of biological uptake by chemical methods may result from the absence of kinetic measurements and application of short exposure periods.

  8. Biological treatment of soils contaminated with hydrophobic organics using slurry- and solid-phase techniques

    Science.gov (United States)

    Cassidy, Daniel H.; Irvine, Robert L.

    1995-10-01

    Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurrying is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bio-slurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay loam contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the rate an extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies. Results showed that slurrying for 1.5 hours at a water content less than saturation markedly increased the rate and extent of contaminant biodegradation in the solid phase bioreactors compared with soil having no slurry pretreatment. Slurrying the soil at or above its saturation moisture content resulted in lengthy dewatering times which prohibited aeration, thereby delaying the onset of biological treatment in the solid phase bioreactors. Results also showed that properly operated periodic aeration can provide less volatile contaminant removal and a grater fraction of biological contaminant removal than continuous aeration.

  9. Remediation of PCB-contaminated soils. Risk analysis of biological in situ processes

    Energy Technology Data Exchange (ETDEWEB)

    Rein, Arno

    2006-12-08

    Biological in situ measures can be efficient and cost effective options for the remediation of contaminated sites. However, the accepted application requires a detailed and reliable analysis of potential impacts. An important objective is to quantify the potential of contaminant degradation and metabolite formation. This thesis addresses a quantitative multimedia risk assessment. Methodologies and tools were developed for this objective and applied to evaluate in situ bioremediation of soils contaminated with polychlorinated biphenyls (PCBs). Soil bacteria in conjunction with plant roots were addressed (rhizoremediation) with a focus on the use of genetically modified microorganisms (GMOs). PCBs are known to be harmful compounds that are ubiquitously distributed in the environment. PCB contaminations in soil and groundwater were identified as important problems. 209 different congeners are sterically possible, but not all are of environmental significance. PCB congeners of concern were evaluated with respect to their potential toxicity, environmental occurrence and mobility. For this objective, congener specific data on the toxicity potential and the frequency in environmental matrices were collected. To quantify the mobility potential, multimedia modelling was performed applying deterministic and probabilistic procedures. 56 PCB congeners of concern were evaluated, and multimedia risk assessments of PCB-contaminated soils should concentrate on this group. Kinetics parameters were specified for degradation experiments with individual PCB congeners in solution and different bacterial strains. These laboratory assays were performed with wild-type Burkholderia sp. strain LB400 and the genetically modified Pseudomonas fluorescens strains F113pcb and F113L::1180. The F113 derivatives demonstrated a good survival ability in willow (Salix sp.) rhizosphere (mesocosm experiments). Therefore, and due to high depletion rates, rhizoremediation with F113L::1180 and willow

  10. Impact of TiO2 on the chemical and biological transformation of formulated chiral-metalaxyl in agricultural soils.

    Science.gov (United States)

    Huang, Junxing; Zhang, Xu; Liang, Chuanzhou; Hu, Jun

    2018-04-15

    The impacts of TiO 2 on the chemical and biological transformation of racemic metalaxyl wettable powder (rac-metalaxyl WP) in agricultural soils, and soil microorganisms were investigated. Under simulated solar irradiation, TiO 2 highly promoted the transformation of rac-metalaxyl WP without changing the enantiomer fraction, with the promotion amplitude (60-1280%) being dependent on TiO 2 characteristics. TiO 2 characteristics showed different influence on the transformation of rac-metalaxyl WP in soils and aqueous solutions because their characteristics changed differently in soils. The impact of the mancozeb and other co-constituents on the transformation of rac-metalaxyl WP was smaller in soil media than in aqueous solution. Autoclave sterilization changed soil properties and subsequently weakened the promotion effects of TiO 2 on the chemical transformations of rac-metalaxyl WP to 0-233%. Microorganism biomass and bacterial community were not statistically significant changed by TiO 2 exposure regardless of rac-metalaxyl WP, suggesting that the promotional effects occurred mainly through chemical processes. The results also showed TiO 2 -soil interactions may be strengthened with TiO 2 (Degussa P25) aging time in soils, which decreased its promotion amplitude from 1060% (without aging) to 880% (aging for 20 days). Intermediate formed in soil biological transformation process was different from that in TiO 2 photocatalysis process. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Microbial Biomarkers for Native and Agricultural Soil Inputs to Atmospheric Particulate Matter

    Science.gov (United States)

    Fulton, J. M.; Herckes, P.; Fraser, M. P.; Collins, J.; Van Mooy, B. A.

    2017-12-01

    Intense dust storms (haboobs) erode desert soils and cause dramatic short-term increases in particulate matter (PM) concentration in the atmosphere. Background atmospheric PM levels in the southwestern United States also commonly exceed the National Ambient Air Quality Standards, so episodic haboobs and normal weather patterns both contribute to aeolian transport. We analyzed fine (PM2.5) and coarse (PM>2.5) dust fractions sampled in Tempe, Arizona for molecular biomarkers indicative of dust sourced from either native or agricultural soils. We focused on pigments and intact polar lipids (IPLs) that were also in soil crusts collected in the region. The PM samples were taken during two weeks (23 July to 5 August 2014) that included two haboobs during the first week and mostly calm weather with minor rainfall during the second week. We detected scytonemin, a diagnostic pigment biomarker for cyanobacteria, in all PM>2.5 samples, but its concentration was highest in haboob dust. Similarly, scytonemin was only abundant in PM2.5 samples taken during haboobs. Scytonemin is an important component of native biological soil crusts, protecting the crust community from UV radiation, and is ca. two orders of magnitude less abundant in disturbed agricultural soils. In biological soil crusts, scytonemin is associated with extracellular polysaccharides that are produced by cyanobacteria and bind soil into cohesive crusts. The association between scytonemin and haboobs suggests that native soil erosion is facilitated by high energy, episodic events that overcome crust cohesion. IPLs were abundant in agricultural soil crusts and included phosphatidylethanolamine from soil bacteria and a glucosylceramide from fungi. These compounds had similar concentration in haboob and background dust, suggesting agricultural or otherwise disturbed soils contribute more to ambient dust. In this study, we employed a new high resolution mass spectrometric method that produces molecular formulas and

  12. Microenvironments and microscale productivity of cyanobacterial desert crusts

    Science.gov (United States)

    Garcia-Pichel, F.; Belnap, Jayne

    1996-01-01

    We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4a??9.4 mmol O2A?ma??2A?ha??1) and dark respiration (0.81a??3.1 mmol Oa??2A?ma??2A?ha??1) occurring within 1 to several mm from the surface were high enough to drive the formation of marked oxygen microenvironments that ranged from oxygen supersaturation to anoxia. The photosynthetic activity also resulted in localized pH values in excess of 10, 2a??3 units above the soil pH. Differences in metabolic parameters and community structure between two types of crusts were consistent with a successional pattern, which could be partially explained on the basis of the microenvironments. We discuss the significance of high metabolic rates and the formation of microenvironments for the ecology of desert crusts, as well as the advantages and limitations of microsensor-based methods for crust investigation.

  13. Smectite clays in Mars soil - Evidence for their presence and role in Viking biology experimental results

    Science.gov (United States)

    Banin, A.; Rishpon, J.

    1979-01-01

    Evidence for the presence of smectite clays in Martian soils is reviewed and results of experiments with certain active clays simulating the Viking biology experiments are reported. Analyses of Martian soil composition by means of X-ray fluorescence spectrometry and dust storm spectroscopy and Martian geological history strongly suggest the presence of a mixture of weathered ferro-silicate minerals, mainly nontronite and montmorillonite, accompanied by soluble sulphate salts, as major constituents. Samples of montmorillonite and nontronite incubated with (C-14)-formate or the radioactive nutrient medium solution used in the Viking Labeled Release experiment, were found to produce patterns of release of radioactive gas very similar to those observed in the Viking experiments, indicating the iron-catalyzed decomposition of formate as the reaction responsible for the Viking results. The experimental results of Hubbard (1979) simulating the results of the Viking Pyrolytic Release experiment using iron montmorillonites are pointed out, and it is concluded that many of the results of the Viking biology experiments can be explained in terms of the surface activity of smectite clays in catalysis and adsorption.

  14. Spies and Bloggers: New Synthetic Biology Tools to Understand Microbial Processes in Soils and Sediments

    Science.gov (United States)

    Masiello, C. A.; Silberg, J. J.; Cheng, H. Y.; Del Valle, I.; Fulk, E. M.; Gao, X.; Bennett, G. N.

    2017-12-01

    Microbes can be programmed through synthetic biology to report on their behavior, informing researchers when their environment has triggered changes in their gene expression (e.g. in response to shifts in O2 or H2O), or when they have participated in a specific step of an elemental cycle (e.g. denitrification). This use of synthetic biology has the potential to significantly improve our understanding of microbes' roles in elemental and water cycling, because it allows reporting on the environment from the perspective of a microbe, matching the measurement scale exactly to the scale that a microbe experiences. However, synthetic microbes have not yet seen wide use in soil and sediment laboratory experiments because synthetic organisms typically report by fluorescing, making their signals difficult to detect outside the petri dish. We are developing a new suite of microbial programs that report instead by releasing easily-detected gases, allowing the real-time, noninvasive monitoring of behaviors in sediments and soils. Microbial biosensors can, in theory, be programmed to detect dynamic processes that contribute to a wide range of geobiological processes, including C cycling (biofilm production, methanogenesis, and synthesis of extracellular enzymes that degrade organic matter), N cycling (expression of enzymes that underlie different steps of the N cycle) and potentially S cycling. We will provide an overview of the potential uses of gas-reporting biosensors in soil and sediment lab experiments, and will report the development of the systematics of these sensors. Successful development of gas biosensors for laboratory use will require addressing issues including: engineering the intensity and selectivity of microbial gas production to maximize the signal to noise ratio; normalizing the gas reporter signal to cell population size, managing gas diffusion effects on signal shape; and developing multiple gases that can be used in parallel.

  15. Are biological effects of desert shrubs more important than physical effects on soil microorganisms?

    Science.gov (United States)

    Berg, Naama; Steinberger, Yosef

    2010-01-01

    Vegetation cover plays a major role in providing organic matter and in acting as a physical barrier, with both together contributing to the formation of "fertile islands," which play an active role in prolonging biological activity in desert ecosystems. By undertaking this study, a longterm research, we designed an experiment to separate the two components-the physical and biotic parts of the perennial plants-and to identify the factor that contributes the most to the ecosystem. The study site was located in the northern Negev Desert, Israel, where 50 Hammada scoparia shrubs and 50 artificial plants were randomly marked. Soil samples were collected monthly over 3 years of research at three locations: under the canopy of H. scoparia shrubs, in the vicinity of the artificial plants, and between the shrubs (control). The contribution to microbial activity was measured by evaluation of the microbial community functions in soil. The functional aspects of the microbial community that were measured were CO2 evolution, microbial biomass, microbial functional diversity, and the physiological profile of the community. The results of this study are presented in two ways: (1) according to the three locations/treatments; and (2) according to the phenological situation of the vegetation (annual and perennial plants) in the research field: the growing phase, the drying process, and the absence of annual plants. The only parameters that were found to affect microbial activity were the contribution of the organic matter of perennial shrubs and the growth of vegetation (annual and perennial) during the growing seasons. The physical component was found to have no effect on soil microbial functional diversity, which elucidates the important contribution of the desert shrub in enhancing biological multiplicity and activity.

  16. The Polar Crust Project- BSC Diversity and Variability in the Arctic and Antarctica

    Science.gov (United States)

    Williams, Laura; Borchhardt, Nadine; Komisc-Buchmann, Karin; Becker, Burkhard; Karsten, Ulf; Büdel, Burkhard

    2015-04-01

    The Polar Crust Project is a newly funded DFG initiative that aims to provide a precise evaluation of the biodiversity of eukaryotic green microalgae and cyanobacteria in Biological Soil Crusts (BSC) isolated from the Antarctic Peninsula and Arctic Svalbard. This project will include a thorough investigation into the composition of BSC in the Polar regions, this especially is important for Svalbard due to the severe lack of any previous research on such communities in this area. During our expedition to Spitsbergen, Svalbard in August 2014 we were particularly surprised to find that the coverage of BSC is extremely high and is certainly the dominant vegetation type around Ny Ålesund. Due to this discovery the project has now been extended to include long term measurements of CO2 gas exchange in order to gain exact seasonal carbon fixation rates and therefore discovering how the BSC contributes to the ecosystems carbon balance. The research areas of Spitsbergen were centred around 2 localities: Ny-Ålesund is a research town, home to the AWIPEV station, on the Brøgger peninsula. Longyearbyen, which is the largest settlement on the island, is found in the valley Longyeardalen on the shore of Adventfjorden. Areas where BSC is the prevalent vegetation type were identified, 6 around Ny-Ålesund and 4 for Longyearbyen, and vegetation surveys were conducted. This entailed 625 single point measurements at each site and identifying the crust/or other cover type. For example, green algal lichen, cyanobacterial crust, higher plant, open soil. Samples were also taken at every location in order to study the green algal and cyanobacterial diversity. The vegetation survey will allow us to get a good overview of the BSC composition at the different sites. In January 2015 an expedition to the Antarctic Peninsular took place, here the sampling method was repeated and therefore both Polar Regions BSC composition can be described and compared. Here, we wish to introduce the Polar

  17. Soil microbiology and soil health assessment

    Science.gov (United States)

    Soil scientists have long recognized the importance of soil biology in ecological health. In particular, soil microbes are crucial for many soil functions including decomposition, nutrient cycling, synthesis of plant growth regulators, and degradation of synthetic chemicals. Currently, soil biologis...

  18. The Effects of Environmental Factors on Biological Remediation of Petroleum Hydrocarbon Contaminated Soil

    Directory of Open Access Journals (Sweden)

    Mohammad reza Moslemi

    2005-09-01

    Full Text Available Among the consequences of discharging industrial wastes to land and water bodies, is the widespread accumulation and migration of toxic chemical mixtures in soil and groundwater resources. It is believed that the accumulation of contaminants in the environment constitutes a serious threat to ecological and human health. Bioremediation is an effective measure in dealing with such contaminations particularly those from petroleum hydrocarbon sources; moreover bioremediation is emerging as a promising technology for the treatment of soil and groundwater contamination. Therefore the goal of this study is discussing the theory and practice of biological remediation of petroleum hydrocarbon contaminated soils and assessing the effects of operational conditions and parameters such as: temperature, dissolved oxygen concentration and  pH on the removal rate of the target contaminant which is handled in the designed reactor. Due to large production and consumption rate of diesel fuel inIran and many other countries, diesel fuel has been selected as target contaminant. In this study TOC and COD testing methods have been used to measure and assess the removal rate of the contaminant in the reactor. The experimental results indicate that, considering the operational conditions the indigenous microorganisms which have been separated from the soil are able to remove 50 to 83 percent of the contaminant after 30 days. Thereafter on the base of the results and considering the laboratorial specifications and conditions applied in this project, the optimum values of temperature, dissolved oxygen concentration andpH were respectively determined as 35°C, 4mg/L and 7.

  19. Ecophysiological traits of various genotypes of a green key alga in biological soil crusts from the semi-arid Colorado Plateau, USA

    Czech Academy of Sciences Publication Activity Database

    Donner, A.; Ryšánek, David; Mikhailyuk, T.; Karsten, U.

    2017-01-01

    Roč. 26, č. 3 (2017), s. 2911-2923 ISSN 0921-8971 Institutional support: RVO:61388971 Keywords : Terrestrial algae * Desiccation * Photosynthesis Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.616, year: 2016

  20. Inter comparison of 90Sr and 137Cs contents in biologic samples and natural U in soil samples

    International Nuclear Information System (INIS)

    Liu Jianfen; Zeng Guangjian; Lu Xuequan

    2001-01-01

    The results of the 90 Sr and 137 Cs contents in biologic samples and the natural U in soil samples obtained in a joint effort by fourteen environmental radiation laboratories in the Chinese environmental protection system were analyzed and compared. Two kinds of biologic samples and one kind of soil samples were used for inter comparison. Of which, one kind of biologic samples (biologic powder samples) and the soil samples came from the IAEA samples were environmental and the reference values were known. The another kind of biologic samples were environmental tea-leaf that were taken from a tea garden near Hangzhou. The mean values obtained by all the joined laboratories was used as the reference. The inter comparison results were expressed in terms of the deviation from the reference value. It was found that the deviation of the 90 Sr and 137 Cs contents of biologic powder samples ranged from -15.4% to 26.5% and -15.0% to 0.4%, respectively. The deviation of the natural U content ranged from -25.5% to 7.3% for the soil samples. For the tea-leaf, the 90 Sr deviation was -22.7% to 19.1%, and the 137 Cs data had a relative large scatter with a ratio of the maximum and the minimum values being about 7. It was pointed out that the analysis results offered by different laboratories might have involved system errors

  1. Collisional stripping of planetary crusts

    Science.gov (United States)

    Carter, Philip J.; Leinhardt, Zoë M.; Elliott, Tim; Stewart, Sarah T.; Walter, Michael J.

    2018-02-01

    Geochemical studies of planetary accretion and evolution have invoked various degrees of collisional erosion to explain differences in bulk composition between planets and chondrites. Here we undertake a full, dynamical evaluation of 'crustal stripping' during accretion and its key geochemical consequences. Crusts are expected to contain a significant fraction of planetary budgets of incompatible elements, which include the major heat producing nuclides. We present smoothed particle hydrodynamics simulations of collisions between differentiated rocky planetesimals and planetary embryos. We find that the crust is preferentially lost relative to the mantle during impacts, and we have developed a scaling law based on these simulations that approximates the mass of crust that remains in the largest remnant. Using this scaling law and a recent set of N-body simulations of terrestrial planet formation, we have estimated the maximum effect of crustal stripping on incompatible element abundances during the accretion of planetary embryos. We find that on average approximately one third of the initial crust is stripped from embryos as they accrete, which leads to a reduction of ∼20% in the budgets of the heat producing elements if the stripped crust does not reaccrete. Erosion of crusts can lead to non-chondritic ratios of incompatible elements, but the magnitude of this effect depends sensitively on the details of the crust-forming melting process on the planetesimals. The Lu/Hf system is fractionated for a wide range of crustal formation scenarios. Using eucrites (the products of planetesimal silicate melting, thought to represent the crust of Vesta) as a guide to the Lu/Hf of planetesimal crust partially lost during accretion, we predict the Earth could evolve to a superchondritic 176Hf/177Hf (3-5 parts per ten thousand) at present day. Such values are in keeping with compositional estimates of the bulk Earth. Stripping of planetary crusts during accretion can lead to

  2. [Biological treatments for contaminated soils: hydrocarbon contamination. Fungal applications in bioremediation treatment].

    Science.gov (United States)

    Martín Moreno, Carmen; González Becerra, Aldo; Blanco Santos, María José

    2004-09-01

    Bioremediation is a spontaneous or controlled process in which biological, mainly microbiological, methods are used to degrade or transform contaminants to non or less toxic products, reducing the environmental pollution. The most important parameters to define a contaminated site are: biodegradability, contaminant distribution, lixiviation grade, chemical reactivity of the contaminants, soil type and properties, oxygen availability and occurrence of inhibitory substances. Biological treatments of organic contaminations are based on the degradative abilities of the microorganisms. Therefore the knowledge on the physiology and ecology of the biological species or consortia involved as well as the characteristics of the polluted sites are decisive factors to select an adequate biorremediation protocol. Basidiomycetes which cause white rot decay of wood are able to degrade lignin and a variety of environmentally persistent pollutants. Thus, white rot fungi and their enzymes are thought to be useful not only in some industrial process like biopulping and biobleaching but also in bioremediation. This paper provides a review of different aspects of bioremediation technologies and recent advances on ligninolytic metabolism research.

  3. Edaphic macrofauna as biological indicator of the conservation/disturbance status of soil. Results obtained in Cuba

    International Nuclear Information System (INIS)

    Cabrera, Grisel

    2012-01-01

    In order to predict the degradation status of a soil, a group of variables comprising its physical, chemical and/or biological properties is used. Macrofauna, which includes soil invertebrates higher than 2 mm of diameter, is a biological component that can be used for such purpose. Its taxonomic richness as well as its density, biomass and functional composition change depending on the effect of diverse land uses and managements. This review reaffirms that the macrofauna characteristics and the results obtained, mainly in Cuba, about its variation in ecosystems with different anthropization levels, support the potential use of this fauna as biological indicator of the soil's conservation status. Future studies should consider a lower taxonomic level in the identification of macrofauna, and relate its taxonomic and functional composition to the climate and pedological factors. (author)

  4. Antagonistic Activity of Trichoderma ISolates against Sclerotium rolfsii : Screening of Efficient Isolates from Morocco Soils for Biological Control

    Directory of Open Access Journals (Sweden)

    N. Khattabi

    2004-12-01

    Full Text Available Seventy Trichoderma spp. isolates collected from different regions of Morocco were tested for their capacity to inhibit in vitro mycelial growth of Sclerotium rolfsii, and for their effect on the viability of S. rolfsii sclerotia in the soil. The Trichoderma spp. isolates inhibited mycelial growth of S. rolfsii to various degrees, with 52% of isolates expressing an average inhibition, varying between 45 and 55%. The effect on the viability of sclerotia in the soil also varied between isolates of Trichoderma, with the majority (84% having a slight effect. A group of twenty isolates identified as Trichoderma harzianum when tested in sterilized soil, significantly reduced sclerotial viability though not in natural soil. Four of these isolates (Nz, Kb2, Kb3 and Kf1 showed good antagonistic activity against S. rolfsii and were also highly competitive in natural soil. These isolates would therefore be candidates for development in biological control program.

  5. Soil microbial community structure in diverse land use systems:A comparative study using Biolog,DGGE,and PLFA analyses

    Institute of Scientific and Technical Information of China (English)

    XUE Dong; YAO Huai-Ying; GE De-Yong; HUANG Chang-Yong

    2008-01-01

    Biolog,16S rRNA gene denaturing gradient gel electrophoresis (DGGE),and phospholipid fatty acid (PLFA) analyses were used to assess soil microbial community characteristics in a chronosequence of tea garden systems (8-,50-,and 90year-old tea gardens),an adjacent wasteland,and a 90-year-old forest.Biolog analysis showed that the average well color development (AWCD) of all carbon sources and the functional diversity based on the Shannon index decreased (P<0.05)in the following order:wasteland>forest>tea garden.For the DGGE analysis,the genetic diversity based on the Shannon index was significantly lower in the tea garden soils than in the wasteland.However,compared to the 90-year-old forest,the tea garden soils showed significantly higher genetic diversity.PLFA analysis showed that the ratio of Gram positive bacteria to Gram negative bacteria was significantly higher in the tea garden soils than in the wasteland,and the highest value was found in the 90-year-old forest.Both the fungal PLFA and the ratio of fungi to bacteria were significantly higher in the three tea garden soils than in the wasteland and forest,indicating that fungal PLFA was significantly affected by land-use change.Based on cluster analysis of the soil microbial community structure,all three analytical methods showed that land-use change had a greater effect on soil microbial community structure than tea garden age.

  6. Human land-use and soil change

    Science.gov (United States)

    Wills, Skye A.; Williams, Candiss O.; Duniway, Michael C.; Veenstra, Jessica; Seybold, Cathy; Pressley, DeAnn

    2017-01-01

    Soil change refers to the alteration of soil and soil properties over time in one location, as opposed to soil variability across space. Although soils change with pedogensis, this chapter focuses on human caused soil change. Soil change can occur with human use and management over long or short time periods and small or large scales. While change can be negative or positive; often soil change is observed when short-term or narrow goals overshadow the other soil’s ecosystem services. Many soils have been changed in their chemical, physical or biological properties through agricultural activities, including cultivation, tillage, weeding, terracing, subsoiling, deep plowing, manure and fertilizer addition, liming, draining, and irrigation. Assessing soil change depends upon the ecosystem services and soil functions being evaluated. The interaction of soil properties with the type and intensity of management and disturbance determines the changes that will be observed. Tillage of cropland disrupts aggregates and decreases soil organic carbon content which can lead to decreased infiltration, increased erosion, and reduced biological function. Improved agricultural management systems can increase soil functions including crop productivity and sustainability. Forest management is most intensive during harvesting and seedling establishment. Most active management in forests causes disturbance of the soil surface which may include loss of forest floor organic materials, increases in bulk density, and increased risk of erosion. In grazing lands, pasture management often includes periods of biological, chemical and physical disturbance in addition to the grazing management imposed on rangelands. Grazing animals have both direct and indirect impacts on soil change. Hoof action can lead to the disturbance of biological crusts and other surface features impairing the soil’s physical, biological and hydrological function. There are clear feedbacks between vegetative systems

  7. The impact of land use on biological activity of agriculture soils. An State-of-the-Art

    Science.gov (United States)

    Morugán-Coronado, Alicia; Cerdà, Artemi; García-Orenes, Fuensanta

    2014-05-01

    Biological activity is a crucial soil property affecting soil sustainability and crop production. The unsuitable land management can lead to a loss in soil fertility and a reduction in the abundance and diversity of soil microorganisms. This can be as a consequence of high erosion rates due to the mismanagement of farmers (Cerdà et al., 2009a). However ecological practices and some organic amendments can promote the activities of soil microbial communities, and increase its biodiversity (García-Orenes et al., 2010; 2013). The impact of land use in microbiological properties of agriculture soil are presented and discussed in this review. Biological activity is quantified by microbial soil communities and soil enzyme activities to interpret the effects of soil management practices (Morugán-Coronado et al., 2013). The aim of biological activity tests is to give a reliable description of the state of agricultural soils under the effect of different land uses. Numerous methods have been used to determine the impact of land uses on microbiological properties. The current used methods for detecting microbial diversity are based on molecular techniques centered on the 16S and 18S rRNA encoding sequences such as CLPP: community-level physiological profiles; T-RFLP: terminal restriction fragment length polymorphism; DGGE: denaturing gradient gel electrophoresis; OFRG: oligonucleotide fingerprinting of rRNA genes, ARISA: Automated Ribosomal intergenic spacer analysis, SSCP: single-strand conformation polymorphism. And techniques based on the cellular composition of the microbes such as PLFA: phospholipid fatty acid analysis. Other methods are based on the activity of microbes, for example, Cmic: microbial biomass carbon; SIR: substrate induced respiration; BSR: Basal soil respiration; qCO2 metabolic quotient; enzymatic activities (Urease, ß-glucosidase and phosphatase) (Deng, 2012). Agricultural land management can contribute to increased rates of erosion due to

  8. Microbial biomass and biological activity of soils and soil-like bodies in coastal oases of Antarctica

    Science.gov (United States)

    Nikitin, D. A.; Marfenina, O. E.; Kudinova, A. G.; Lysak, L. V.; Mergelov, N. S.; Dolgikh, A. V.; Lupachev, A. V.

    2017-09-01

    The method of luminescent microscopy has been applied to study the structure of the microbial biomass of soils and soil-like bodies in East (the Thala Hills and Larsemann Hills oases) and West (Cape Burks, Hobbs coast) Antarctica. According to Soil Taxonomy, the studied soils mainly belong to the subgroups of Aquic Haploturbels, Typic Haploturbels, Typic Haplorthels, and Lithic Haplorthels. The major contribution to their microbial biomass belongs to fungi. The highest fungal biomass (up to 790 μg C/g soil) has been found in the soils with surface organic horizons in the form of thin moss/lichen litters, in which the development of fungal mycelium is most active. A larger part of fungal biomass (70-98%) is represented by spores. For the soils without vegetation cover, the accumulation of bacterial and fungal biomass takes place in the horizons under surface desert pavements. In the upper parts of the soils without vegetation cover and in the organic soil horizons, the major part (>60%) of fungal mycelium contains protective melanin pigments. Among bacteria, the high portion (up to 50%) of small filtering forms is observed. A considerable increase (up to 290.2 ± 27 μg C/g soil) in the fungal biomass owing to the development of yeasts has been shown for gley soils (gleyzems) developing from sapropel sediments under subaquatic conditions and for the algal-bacterial mat on the bottom of the lake (920.7 ± 46 μg C/g soil). The production of carbon dioxide by the soils varies from 0.47 to 2.34 μg C-CO2/(g day). The intensity of nitrogen fixation in the studied samples is generally low: from 0.08 to 55.85 ng C2H4/(g day). The intensity of denitrification varies from 0.09 to 19.28 μg N-N2O/(g day).

  9. Effects of aerobic and anaerobic biological processes on leaching of heavy metals from soil amended with sewage sludge compost.

    Science.gov (United States)

    Fang, Wen; Wei, Yonghong; Liu, Jianguo; Kosson, David S; van der Sloot, Hans A; Zhang, Peng

    2016-12-01

    The risk from leaching of heavy metals is a major factor hindering land application of sewage sludge compost (SSC). Understanding the change in heavy metal leaching resulting from soil biological processes provides important information for assessing long-term behavior of heavy metals in the compost amended soil. In this paper, 180days aerobic incubation and 240days anaerobic incubation were conducted to investigate the effects of the aerobic and anaerobic biological processes on heavy metal leaching from soil amended with SSC, combined with chemical speciation modeling. Results showed that leaching concentrations of heavy metals at natural pH were similar before and after biological process. However, the major processes controlling heavy metals were influenced by the decrease of DOC with organic matter mineralization during biological processes. Mineralization of organic matter lowered the contribution of DOC-complexation to Ni and Zn leaching. Besides, the reducing condition produced by biological processes, particularly by the anaerobic biological process, resulted in the loss of sorption sites for As on Fe hydroxide, which increased the potential risk of As release at alkaline pH. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Palaeomagnetism and the continental crust

    Energy Technology Data Exchange (ETDEWEB)

    Piper, J.D.A.

    1987-01-01

    This book is an introduction to palaeomagnetism offering treatment of theory and practice. It analyzes the palaeomagnetic record over the whole of geological time, from the Archaean to the Cenozoic, and goes on to examine the impact of past geometries and movements of the continental crust at each geological stage. Topics covered include theory of rock and mineral magnetism, field and laboratory methods, growth and consolidation of the continental crust in Archaean and Proterozoic times, Palaeozoic palaeomagnetism and the formation of Pangaea, the geomagnetic fields, continental movements, configurations and mantle convection.

  11. A combined approach of physicochemical and biological methods for the characterization of petroleum hydrocarbon-contaminated soil.

    Science.gov (United States)

    Masakorala, Kanaji; Yao, Jun; Chandankere, Radhika; Liu, Haijun; Liu, Wenjuan; Cai, Minmin; Choi, Martin M F

    2014-01-01

    Main physicochemical and microbiological parameters of collected petroleum-contaminated soils with different degrees of contamination from DaGang oil field (southeast of Tianjin, northeast China) were comparatively analyzed in order to assess the influence of petroleum contaminants on the physicochemical and microbiological properties of soil. An integration of microcalorimetric technique with urease enzyme analysis was used with the aim to assess a general status of soil metabolism and the potential availability of nitrogen nutrient in soils stressed by petroleum-derived contaminants. The total petroleum hydrocarbon (TPH) content of contaminated soils varied from 752.3 to 29,114 mg kg(−1). Although the studied physicochemical and biological parameters showed variations dependent on TPH content, the correlation matrix showed also highly significant correlation coefficients among parameters, suggesting their utility in describing a complex matrix such as soil even in the presence of a high level of contaminants. The microcalorimetric measures gave evidence of microbial adaptation under highest TPH concentration; this would help in assessing the potential of a polluted soil to promote self-degradation of oil-derived hydrocarbon under natural or assisted remediation. The results highlighted the importance of the application of combined approach in the study of those parameters driving the soil amelioration and bioremediation.

  12. Relationship among soil surface properties, hydrology and nitrogen cycling along a climatological gradient in drylands

    Science.gov (United States)

    Zaady, E.; Segoli, M.; Eldridge, D. J.; Groffman, P. M.; Boeken, B.; Shachak, M.

    2009-04-01

    Primary production and nutrient cycling in dryland systems are limited by water supply. There are two groups of primary producers, high biomass production plants and low biomass producing organisms found in biological soil crusts (BSC's), which control energy flow, nutrient cycling and hydrology. Biological or biogenic soil crusts are common in the world's drylands, from dry sub-humid to hyper-arid systems. The crusts are formed by communities of microphytes, mainly cyanobacteria, green algae, mosses, and lichens. The extracellular polysaccharide materials produced by the crust organisms attach soil particles, creating a solid horizontal layer of crust. Biological soil crusts modify soil quality by (1) aggregating soil particles, thereby reducing wind and water erosion; (2) reducing water infiltration, causing overland water run-off; and (3) N fixation and C sequestration. Dryland landscapes are two phase mosaic composed of BSC and high production patches. Development or loss of BSC may trigger changes in the spatial distribution of the patch types and therefore transitions between functional and degraded ecosystem states. We present a conceptual model depicting the function of each patch type and the link between them. Taking into account the contrast between low and high vegetation cover of dryland systems and their role in controlling soil nitrogen and water flows. The model describes the functioning of dryland systems with low biomass producing crust organisms cover, low rainfall, low top soil water and production, which cause low infiltration rate, low N uptake, nitrate accumulation, high evaporation and runoff. This leads to leaching of nitrates, oxygen depletion with high anaerobic conditions, high denitrification rates and N loss, resulting in low plant cover and soil organic matter i.e., degraded soil. It also depicts the functioning of the high production plants under low rainfall regimes resulting in low rates of N and energy flows. The model shows that

  13. Effects of seasonal olive mill wastewater applications on hydrological and biological soil properties in an olive orchard in Israel

    Science.gov (United States)

    Steinmetz, Zacharias; Kurtz, Markus; Peikert, Benjamin; Zipori, Isaac; Dag, Arnon; Schaumann, Gabriele E.

    2014-05-01

    During olive oil production in Mediterranean countries, large amounts of olive mill wastewater (OMW) are generated within a short period of time. OMW has a high nutrient content and could serve as fertilizer when applied on land. However, its fatty and phenolic constituents have adverse effects on hydrological and biological soil properties. It is still unknown how seasonal fluctuations in temperature and precipitation influence the fate and effect of OMW components on soil in a long-term perspective. An appropriate application season could mitigate negative consequences of OMW while preserving its beneficial effects. In order to investigate this, 14 L OMW m-2 were applied to different plots of an olive orchard in Gilat, Israel, in winter, spring, and summer, respectively. Hydrological soil properties (water drop penetration time, hydraulic conductivity, dynamic contact angle), physicochemical parameters (pH, EC, soluble ions, phenolic compounds, organic matter), and biological degradation (bait-lamina test) were measured to assess the soil state after OMW application. After one rainy season following OMW application, the soil quality of summer treatments significantly decreased compared to the control. This was particularly apparent in a ten-fold higher soil water repellency, a three-times lower biodegradation performance, and a four-fold higher content of phenolic compounds. 1.5 years after the last OMW application, the soil properties of winter treatments were comparable to the control, which suggests a certain recovery potential of the soil. Spring treatments resulted in an intermediate response compared to summer and winter treatments, but without any precipitation following OMW application. Strongest OMW effects were found in the top soil layers. Further research is needed to quantify the effect of spring treatments as well as to gain further insight into leaching effects, the composition of organic OMW constituents, and the kinetics of their degradation in

  14. The effect of humus on biological cleaning of soils - association of harmful organic substances from mineral oil contaminators

    International Nuclear Information System (INIS)

    Richnow, H.H.; Seifert, R.; Michaelis, W.

    1993-01-01

    The association of organic harmful substances and particularly their metabolites with the humin fraction is a process which has great ecological importance. The knowledge of the type and extent of such associations of harmful substances with the humin fraction of the soil plays a central part in the assessment of loading by harmful substances or the success of biological cleaning up measures. (orig.) [de

  15. Impacts of insect biological control on soil N transformations in Tamarix-invaded ecosystems in the Great Basin

    Science.gov (United States)

    Understanding the impacts of insect biological control of Tamarix spp. on soil nitrogen (N) transformations is important because changes to N supply could alter plant community succession. We investigated short-term and longer-term impacts of herbivory by the northern tamarisk beetle (Diorhabda cari...

  16. The practicalities and pitfalls of establishing a policy-relevant and cost-effective soil biological monitoring scheme

    NARCIS (Netherlands)

    Faber, J.H.; Creamer, R.E.; Mulder, C.; Römbke, J.; Rutgers, M.; Sousa, J.P.; Stone, D.; Griffiths, B.S.

    2013-01-01

    A large number of biological indicators have been proposed over the years for assessing soil quality. Although many of those have been applied in monitoring schemes across Europe, no consensus exists on the extent to which these indicators might perform best and how monitoring schemes can be further

  17. Does grazing of cover crops impact biologically active soil C and N fractions under inversion and no tillage management

    Science.gov (United States)

    Cover crops are a key component of conservation cropping systems. They can also be a key component of integrated crop-livestock systems by offering high-quality forage during short periods between cash crops. The impact of cattle grazing on biologically active soil C and N fractions has not receiv...

  18. Top layer enhances biological ontrol of thrips in ornamentals :"Predatory mites survive better on rich soil cover

    NARCIS (Netherlands)

    Hoogstraten, van K.; Grosman, A.H.

    2014-01-01

    An organic top layer over the soil or substrate can enhance the biological control of thrips in roses and alstroemerias. The top layer contains food for prey mites, which in turn serve as food for predatory mites. In this way the predators survive longer. Thus, as the thrips population increases, an

  19. Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO2 efflux in two semiarid grasslands in southern Botswana

    Science.gov (United States)

    Thomas, Andrew D.

    2012-01-01

    Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO2 efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO2 efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO2 efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO2 efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO2 efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a, organic carbon and scytonemin. Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands. PMID:23045706

  20. Statistics of Magnetar Crusts Magnetoemission

    Directory of Open Access Journals (Sweden)

    Kondratyev V. N.

    2016-01-01

    Full Text Available Soft repeating gamma-ray (SGR bursts are considered as magnetoemission of crusts of magnetars (ultranamagnetized neutron stars. It is shown that all the SGR burst observations can be described and systematized within randomly jumping interacting moments model including quantum fluctuations and internuclear magnetic interaction in an inhomogeneous crusty nuclear matter.

  1. The activity and community structure of total bacteria and denitrifying bacteria across soil depths and biological gradients in estuary ecosystem.

    Science.gov (United States)

    Lee, Seung-Hoon; Kang, Hojeong

    2016-02-01

    The distribution of soil microorganisms often shows variations along soil depth, and even in the same soil layer, each microbial group has a specific niche. In particular, the estuary soil is intermittently flooded, and the characteristics of the surface soil layer are different from those of other terrestrial soils. We investigated the microbial community structure and activity across soil depths and biological gradients composed of invasive and native plants in the shallow surface layer of an estuary ecosystem by using molecular approaches. Our results showed that the total and denitrifying bacterial community structures of the estuarine wetland soil differed according to the short depth gradient. In growing season, gene copy number of 16S rRNA were 1.52(±0.23) × 10(11), 1.10(±0.06) × 10(11), and 4.33(±0.16) × 10(10) g(-1) soil; nirS were 5.41(±1.25) × 10(8), 4.93(±0.94) × 10(8), and 2.61(±0.28) × 10(8) g(-1) soil; and nirK were 9.67(±2.37) × 10(6), 3.42(±0.55) × 10(6), and 2.12(±0.19) × 10(6) g(-1) soil in 0 cm, 5 cm, and 10 cm depth layer, respectively. The depth-based difference was distinct in the vegetated sample and in the growing season, evidencing the important role of plants in structuring the microbial community. In comparison with other studies, we observed differences in the microbial community and functions even across very short depth gradients. In conclusion, our results suggested that (i) in the estuary ecosystem, the denitrifying bacterial community could maintain its abundance and function within shallow surface soil layers through facultative anaerobiosis, while the total bacterial community would be both quantitatively and qualitatively affected by the soil depth, (ii) the nirS gene community, rather than the nirK one, should be the first candidate used as an indicator of the microbial denitrification process in the estuary system, and (iii) as the microbial community is distributed and plays a certain niche role according to

  2. Isolation and Identification of Phosphate Solubilizing and Nitrogen Fixing Bacteria from Soil in Wamena Biological Garden, Jayawijaya, Papua

    Directory of Open Access Journals (Sweden)

    SRI WIDAWATI

    2005-07-01

    Full Text Available A study was undertaken to investigate the occurrence of phosphate solubilizing bacteria (PSB and nitrogen-fixing bacteria (NFB from soil samples of Wamena Biological Garden (WbiG. Eleven soil samples were collected randomly to estimate microbial population which used plate count method. The result showed that the microbial population ranged from 5.0x103-7.5x106 cells of bacteria/gram of soil and 5.0x103-1.5x107 cells of bacteria/gram of soil for PSB and NFB respectively. There were 17 isolates which have been identified till genus and species. The isolated microorganism were identified as PSB i.e. Bacillus sp., B. pantothenticus, B. megatherium, Flavobacterium sp., F. breve, Klebsiella sp., K. aerogenes, Chromobacterium lividum, Enterobacter alvei, E. agglomerans, Pseudomonas sp., Proteus sp. and as NFB i.e. Azotobacter sp., A. chroococcum, A. paspalii, Rhizobium sp., and Azospirillum sp.

  3. Biological transformation of anthracene in soil by Pleurotus ostreatus under solid-state fermentation conditions using wheat bran and compost

    International Nuclear Information System (INIS)

    Vargas, M C; Rodriguez, R; Sanchez, F; Ramirez, N

    2001-01-01

    Pleurotus ostreatus was grown in a soil mixture contaminated with anthracene, wheat bran and compost, in varying combinations. Assays with added bacteria and reinoculation of the fungus were also included. The results indicated that in many of the combinations, most of the anthracene was removed at the earliest sample time, 15 days. The most effective combination was spiked (anthracene-added) soil, fungus and compost and the addition of acclimated bacteria to this mixture inhibited anthracene removal. Analyses of extract by high-pressure liquid chromatography HPLC indicated that - anthraquinone, was the major metabolite formed. The results of this study indicate that solid-state fermentation of anthracene-contaminated soils using P. ostreatus in combination with wheat bran and compost additives can produce an accelerated rate of biological removal of anthracene from the soil

  4. Long-term organic farming fosters below and aboveground biota: Implications for soil quality, biological control and productivity

    DEFF Research Database (Denmark)

    Birkhofer, K.; Bezemer, TM; Bloem, J

    2008-01-01

     Organic farming may contribute substantially to future agricultural production worldwide by improving soil quality and pest control, thereby reducing environmental impacts of conventional farming. We investigated in a comprehensive way soil chemical, as well as below and aboveground biological...... with (CONFYM) or without manure (CONMIN) and herbicide application within a long-term agricultural experiment (DOK trial, Switzerland). Soil carbon content was significantly higher in systems receiving farmyard manure and concomitantly microbial biomass (fungi and bacteria) was increased. Microbial activity...... parameters, such as microbial basal respiration and nitrogen mineralization, showed an opposite pattern, suggesting that soil carbon in the conventional system (CONFYM) was more easily accessible to microorganisms than in organic systems. Bacterivorous nematodes and earthworms were most abundant in systems...

  5. International approach to assessing soil quality by ecologically-related biological parameters

    OpenAIRE

    Filip, Z.

    2002-01-01

    Metadata only record Soil quality represents an integral value of the compositional structures and natural functions of soil in relation to soil use and environmental conditions on site. Among the indigenous soil components, different organisms and especially microorganisms play a key role in ecologically important biogeochemical processes. In that way, soil microorganisms contribute to the maintenance of the matter and energy transfer in terrestrial environments. Under stress conditions c...

  6. Physical, chemical, and biological properties of soil under soybean cultivation and at an adjacent rainforest in Amazonia

    Directory of Open Access Journals (Sweden)

    Troy Patrick Beldini

    2015-11-01

    Full Text Available Land-use change in the Amazon basin has occurred at an accelerated pace during the last decade, and it is important that the effects induced by these changes on soil properties are better understood. This study investigated the chemical, physical, and biological properties of soil in a field under cultivation of soy and rice, and at an adjacent primary rain forest. Increases in soil bulk density, exchangeable cations and pH were observed in the soy field soil. In the primary forest, soil microbial biomass and basal respiration rates were higher, and the microbial community was metabolically more efficient. The sum of basal respiration across the A, AB and BA horizons on a mass per area basis ranged from 7.31 to 10.05 Mg CO2-C ha-1yr-1, thus yielding estimates for total soil respiration between 9.6 and 15.5 Mg CO2-C ha-1yr-1 across sites and seasons. These estimates are in good agreement with literature values for Amazonian ecosystems. The estimates of heterotrophic respiration made in this study help to further constrain the estimates of autotrophic soil respiration and will be useful for monitoring the effects of future land-use in Amazonian ecosystems.

  7. Microbes Persist: Using a Systems Biology Approach to Reveal How the Soil Microbiome Shapes Soil Organic Matter

    Science.gov (United States)

    Pett-Ridge, J.

    2017-12-01

    Soils store more carbon than the atmosphere and terrestrial vegetation combined, yet the factors that control its persistence remain elusive. Recent insights have overturned the long-held assumption that carbon stability depends mostly on chemical `recalcitrance' of soil organic matter (SOM). Instead, an emerging paradigm emphasizes how environmental drivers like temperature and moisture, soil minerals, and microbial ecology interact to control SOM formation, stabilization, and turnover. Detailed spectroscopic and isotopic (14C) analyses of mineral-associated SOM show that the oldest carbon in soil may be easily broken down and respired in the laboratory, and that it biochemically resembles microbial cells and metabolites far more than plant material. This places microbial ecophysiology at the center of the soil carbon persistence question. Microbial cells likely interact with mineral surfaces as part of an ecological strategy to condition their environment (e.g. biofilm formation or extracellular enzyme production), and their diverse cellular components likely associate with minerals after cells die. Collectively, these microbial characteristics - metabolic activities, population growth strategies, and cellular biochemistry - can be thought of as `soil ecophysiological traits'. This presentation will explore potential traits that may be fruitful targets for studies evaluating the persistence and importance of microbial products as SOM precursors, and will highlight results showing that soil mineral type influences the microbial communities that colonize mineral surfaces, as well as the quantity and type of mineral-associated carbon that accumulates. I will propose a series of integrated approaches that used together can examine how genomic capacity and activities of soil microbiomes are shaped by edaphic conditions (moisture, temperature, redox regimes) and fundamentally affect the terrestrial soil C pool.

  8. Conservation agriculture among small scale farmers in semi-arid region of Kenya does improve soil biological quality and soil organic carbon

    Science.gov (United States)

    Waweru, Geofrey; Okoba, Barrack; Cornelis, Wim

    2016-04-01

    The low food production in Sub-Saharan Africa (SSA) has been attributed to declining soil quality. This is due to soil degradation and fertility depletion resulting from unsustainable conventional farming practices such as continuous tillage, crop residue burning and mono cropping. To overcome these challenges, conservation agriculture (CA) is actively promoted. However, little has been done in evaluating the effect of each of the three principles of CA namely: minimum soil disturbance, maximum surface cover and diversified/crop rotation on soil quality in SSA. A study was conducted for three years from 2012 to 2015 in Laikipia East sub county in Kenya to evaluate the effect of tillage, surface cover and intercropping on a wide variety of physical, chemical and biological soil quality indicators, crop parameters and the field-water balance. This abstract reports on soil microbial biomass carbon (SMBC) and soil organic carbon (SOC). The experimental set up was a split plot design with tillage as main treatment (conventional till (CT), no-till (NT) and no-till with herbicide (NTH)), and intercropping and surface cover as sub treatment (intercropping maize with: beans, MB; beans and leucaena, MBL; beans and maize residues at 1.5 Mg ha-1 MBMu, and dolichos, MD). NT had significantly higher SMBC by 66 and 31% compared with CT and NTH respectively. SOC was significantly higher in NTH than CT and NT by 15 and 4%, respectively. Intercropping and mulching had significant effect on SMBC and SOC. MBMu resulted in higher SMBC by 31, 38 and 43%, and SOC by 9, 20 and 22% as compared with MBL, MD and MB, respectively. SMBC and SOC were significantly affected by the interaction between tillage, intercropping and soil cover with NTMBMu and NTHMBMu having the highest SMBC and SOC, respectively. We conclude that indeed tillage, intercropping and mulching substantially affect SMBC and SOC. On the individual components of CA, tillage and surface cover had the highest effect on SMBC and

  9. Elevated temperature altered photosynthetic products in wheat seedlings and organic compounds and biological activity in rhizopshere soil under cadmium stress

    Science.gov (United States)

    Jia, Xia; Zhao, Yonghua; Wang, Wenke; He, Yunhua

    2015-09-01

    The objective of this study was to investigate the effects of slightly elevated atmospheric temperature in the spring on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated temperature was associated with increased soluble sugars, reducing sugars, starch, and total sugars, and with decreased amino acids in wheat seedlings under Cd stress. Elevated temperature improved total soluble sugars, free amino acids, soluble phenolic acids, and organic acids in rhizosphere soil under Cd stress. The activity of amylase, phenol oxidase, invertase, β-glucosidase, and L-asparaginase in rhizosphere soil was significantly improved by elevated temperature under Cd stress; while cellulase, neutral phosphatase, and urease activity significantly decreased. Elevated temperature significantly improved bacteria, fungi, actinomycetes, and total microorganisms abundance and fluorescein diacetate activity under Cd stress. In conclusion, slightly elevated atmospheric temperature in the spring improved the carbohydrate levels in wheat seedlings and organic compounds and biological activity in rhizosphere soil under Cd stress in the short term. In addition, elevated atmospheric temperature in the spring stimulated available Cd by affecting pH, DOC, phenolic acids, and organic acids in rhizosphere soil, which resulted in the improvement of the Cd uptake by wheat seedlings.

  10. Chemical and biological properties of phosphorus-fertilized soil under legume and grass cover (Cerrado region, Brazil

    Directory of Open Access Journals (Sweden)

    Marcelo Fernando Pereira Souza

    2013-12-01

    Full Text Available The use of cover crops has been suggested as an effective method to maintain and/or increase the organic matter content, while maintaining and/or enhancing the soil physical, chemical and biological properties. The fertility of Cerrado soils is low and, consequently, phosphorus levels as well. Phosphorus is required at every metabolic stage of the plant, as it plays a role in the processes of protein and energy synthesis and influences the photosynthetic process. This study evaluated the influence of cover crops and phosphorus rates on soil chemical and biological properties after two consecutive years of common bean. The study analyzed an Oxisol in Selvíria (Mato Grosso do Sul, Brazil, in a randomized block, split plot design, in a total of 24 treatments with three replications. The plot treatments consisted of cover crops (millet, pigeon pea, crotalaria, velvet bean, millet + pigeon pea, millet + crotalaria, and millet + velvet bean and one plot was left fallow. The subplots were represented by phosphorus rates applied as monoammonium phosphate (0, 60 and 90 kg ha-1 P2O5. In August 2011, the soil chemical properties were evaluated (pH, organic matter, phosphorus, potential acidity, cation exchange capacity, and base saturation as well as biological variables (carbon of released CO2, microbial carbon, metabolic quotient and microbial quotient. After two years of cover crops in rotation with common bean, the cover crop biomass had not altered the soil chemical properties and barely influenced the microbial activity. The biomass production of millet and crotalaria (monoculture or intercropped was highest. The biological variables were sensitive and responded to increasing phosphorus rates with increases in microbial carbon and reduction of the metabolic quotient.

  11. Soils

    Science.gov (United States)

    Emily Moghaddas; Ken Hubbert

    2014-01-01

    When managing for resilient forests, each soil’s inherent capacity to resist and recover from changes in soil function should be evaluated relative to the anticipated extent and duration of soil disturbance. Application of several key principles will help ensure healthy, resilient soils: (1) minimize physical disturbance using guidelines tailored to specific soil types...

  12. Direct determination of uranium in soil, rock, ore and biological samples by laser-induced fluorometry

    International Nuclear Information System (INIS)

    Li Qingzhen; Zhang Yanan

    1993-03-01

    A laser-induced fluorometric method with modified J-22 anti-interferent fluorescent reagent for directly determining the uranium in soil, rock, ore, geochemical, biological and other samples has been studied. The effects of external ions and dilution law of sample are examined in detail. A method for correcting inner effect is proposed. A mixed solution of 0.25% NaOH-10% J-22 is prepared which can be added to the sample cuvette for direct measurement without any pre-adjustment of acidity. Therefore, it is much simpler for operation and reduces the loss and contamination of uranium. By changing the laser fluorometer sensitivity (400 ∼ 200), up to 3000 ng uranium in the cuvette can be detected. Thus, both analytical accuracy and detectable range are improved. This method is simple, rapid, accurate and applicable to various uranium-bearing samples. The detection limit is better than 0.05 μgU/g. The relative standard deviation is ≤+-5% for the rock reference samples of 0.95, 84.8, 669 and 7240 μgU/g

  13. Biological treatment of soils contaminated with hydrophobic organics using slurry and solid phase techniques

    International Nuclear Information System (INIS)

    Cassidy, D.P.; Irvine, R.L.

    1995-01-01

    Both slurry-phase and solid-phase bioremediation are effective ex situ soil decontamination methods. Slurry is energy intensive relative to solid-phase treatment, but provides homogenization and uniform nutrient distribution. Limited contaminant bioavailability at concentrations above the required cleanup level reduces biodegradation rates and renders solid phase bioremediation more cost effective than complete treatment in a bioslurry reactor. Slurrying followed by solid-phase bioremediation combines the advantages and minimizes the weaknesses of each treatment method when used alone. A biological treatment system consisting of slurrying followed by aeration in solid phase bioreactors was developed and tested in the laboratory using a silty clay load contaminated with diesel fuel. The first set of experiments was designed to determine the impact of the water content and mixing time during slurrying on the ate and extent of contaminant removal in continuously aerated solid phase bioreactors. The second set of experiments compared the volatile and total diesel fuel removal in solid phase bioreactors using periodic and continuous aeration strategies

  14. Integration into plant biology and soil science has provided insights into the total environment.

    Science.gov (United States)

    Shao, Hongbo; Lu, Haiying; Xu, Gang; Marian, Brestic

    2017-02-01

    The total environment includes 5 closely-linking circles, in which biosphere and lithosphere are the active core. As global population increases and urbanization process accelerates, arable land is gradually decreasing under global climate change and the pressure of various types of environmental pollution. This case is especially for China. Land is the most important resources for human beings' survival. How to increase and manage arable land is the key for sustainable agriculture development. China has extensive marshy land that can be reclamated for the better potential land resources under the pre- condition of protecting the environment, which will be a good way for enlarging globally and managing arable land. Related studies have been conducted in China for the past 30years and now many results with obvious practical efficiency have been obtained. For summarizing these results, salt-soil will be the main target and related contents such as nutrient transport, use types, biodiversity and interactions with plants from molecular biology to ecology will be covered, in which the interactions among biosphere, lithosphere, atmosphere and anthroposphere will be focused on. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Chronology of early lunar crust

    International Nuclear Information System (INIS)

    Dasch, E.J.; Nyquist, L.E.; Ryder, G.

    1988-01-01

    The chronology of lunar rocks is summarized. The oldest pristine (i.e., lacking meteoritic contamination of admixed components) lunar rock, recently dated with Sm-Nd by Lugmair, is a ferroan anorthosite, with an age of 4.44 + 0.02 Ga. Ages of Mg-suite rocks (4.1 to 4.5 Ga) have large uncertainties, so that age differences between lunar plutonic rock suites cannot yet be resolved. Most mare basalts crystallized between 3.1 and 3.9 Ga. The vast bulk of the lunar crust, therefore, formed before the oldest preserved terrestrial rocks. If the Moon accreted at 4.56 Ga, then 120 Ma may have elapsed before lunar crust was formed

  16. Effects of Zero Tillage (No-Till) Conservation Agriculture on soil physical and biological properties and their contributions to sustainability

    Science.gov (United States)

    Landers, John N.; Rass, Gerard; de Freitas, Pedro L.; Basch, Gottlieb; González Sanchez, Emilio J.; Tabaglio, Vincenzo; Kassan, Amir; Derpsch, Rolf; Friedrich, Theodor; Giupponi, Luca

    2013-04-01

    Not cultivating soil, rotating crops over the years, and leaving crop residues on the surface in the practice of zero tillage/conservation agriculture (ZT/CA) reverses the historically accelerating degradation of soil organic matter (SOM) and soil structure, while increasing soil biological activity by a factor of 2 to 4. The results of this are many: (a) not cultivating reduces soil compaction, leaving old root holes to facilitate internal drainage, averts the pulverization of soil aggregates and formation of pans, reduces draft power for planting and gives shelter, winter food and nesting sites for fauna, (b) crop residues on the surface practically eliminate wind and water erosion, reduce soil moisture loss through the mulch effect, slow spring warm-up (possibly offset by a lower specific heat demand with less water retention in surface soil) and act as a reserve of organically-compounded nutrients (as they decompose to humus), (c) more SOM means higher available water and nutrient retention, higher biological activity year round (enhancing biological controls), higher levels of water-stable aggregates and a positive carbon sink in incremental SOM. The positive impacts for society are: (i) more and cheaper food, (ii) reduced flood and drought-induced famine risks, (iii) a positive carbon sink in SOM and possible reductions in NO2 emissions, (iv) cleaner water and greater aquifer recharge due to reduced runoff, (v) cleaner air through effective elimination of dust as a product of cultivation (vi) less water pollution and greater aquifer recharge from reduced rainfall runoff, (vii) farm diesel consumption halved, (viii) reduced demand for (tropical) de-forestation, by permitting crop expansion on steeper lands, (ix) increased wildlife populations (skylarks, plovers, partridge and peccaries) and (x) an improved conservation mindset in farmers. It is notable that, in spite of successful practitioners in all European countries, mainstream adoption is still to come

  17. Physics of the earth crust

    International Nuclear Information System (INIS)

    Lauterbach, R.

    1977-01-01

    This book deals in 12 chapters, amongst other things, with the subjects: Structure of the crust and the upper earth mantle, geology and geophysics of sea beds, satellite and aero-methods of geophysics, state of the art of geothermal research, geophysical potential fields and their anomalies, applied seismology, electrical methods of geophysics, geophysics in engineering and rock engineering, borehole geophysics, petrophysics, and geochemistry. (RW) [de

  18. The impact of the Almalyk Industrial Complex on soil chemical and biological properties

    International Nuclear Information System (INIS)

    Shukurov, Nosir; Pen-Mouratov, Stanislav; Steinberger, Yosef

    2005-01-01

    The effect of heavy metals on soil free-living nematodes, microbial biomass (C mic ) and basal respiration (BR) was studied along a 15 km downwind deposition gradient, originating at the Almalyk Industrial Complex. Soil samples from 0-10 and 10-20 cm layers were collected at 5 km intervals. A significant decrease in heavy metal deposition was found going from the source in the downwind direction and with depth. The soil microbial biomass, basal respiration and derived microbial indices for soil samples from the Almalyk industrial area were analysed. The lowest soil microbial biomass and total number of free-living nematodes were found in soil samples near the industrial complex, with a high heavy metal and weak total organic carbon (C org ) content. The highest C mic was found in the soil samples collected 15 km from the pollution source. BR displayed similar results. The derived indices, metabolic quotient (qCO 2 ) and microbial ratio (C mic /C org ), revealed significant differences with distance, confirming environmental stress in the first and second locations. The present study elucidates the importance of soil nematode and microbial populations as suitable tools for bio-monitoring the effect of heavy metals on soil systems. - Soil nematodes and microbes are suitable biomonitors for metals in soils

  19. Elevated atmospheric CO2 affected photosynthetic products in wheat seedlings and biological activity in rhizosphere soil under cadmium stress.

    Science.gov (United States)

    Jia, Xia; Liu, Tuo; Zhao, Yonghua; He, Yunhua; Yang, Mingyan

    2016-01-01

    The objective of this study was to investigate the effects of elevated CO2 (700 ± 23 μmol mol(-1)) on photosynthetic products in wheat seedlings and on organic compounds and biological activity in rhizosphere soil under cadmium (Cd) stress. Elevated CO2 was associated with decreased quantities of reducing sugars, starch, and soluble amino acids, and with increased quantities of soluble sugars, total sugars, and soluble proteins in wheat seedlings under Cd stress. The contents of total soluble sugars, total free amino acids, total soluble phenolic acids, and total organic acids in the rhizosphere soil under Cd stress were improved by elevated CO2. Compared to Cd stress alone, the activity of amylase, phenol oxidase, urease, L-asparaginase, β-glucosidase, neutral phosphatase, and fluorescein diacetate increased under elevated CO2 in combination with Cd stress; only cellulase activity decreased. Bacterial abundance in rhizosphere soil was stimulated by elevated CO2 at low Cd concentrations (1.31-5.31 mg Cd kg(-1) dry soil). Actinomycetes, total microbial abundance, and fungi decreased under the combined conditions at 5.31-10.31 mg Cd kg(-1) dry soil. In conclusion, increased production of soluble sugars, total sugars, and proteins in wheat seedlings under elevated CO2 + Cd stress led to greater quantities of organic compounds in the rhizosphere soil relative to seedlings grown under Cd stress only. Elevated CO2 concentrations could moderate the effects of heavy metal pollution on enzyme activity and microorganism abundance in rhizosphere soils, thus improving soil fertility and the microecological rhizosphere environment of wheat under Cd stress.

  20. Recovery of Areas Degraded by Mining Within the Amazon Forest: Interaction of the Physical Condition of Soil and Biological Activity

    Science.gov (United States)

    Ribeiro, A. I.; Mello, G. F.; Longo, R. M.; Fengler, F. H.; Peche Filho, A., Sr.

    2017-12-01

    One of the greatest natural riches of Brazil is the Amazon rainforest. The Amazon region is known for its abundance of mineral resources, and may include topaz, oil, and especially cassiterite. In this scope, the mining sector in Brazil has great strategic importance because it accounts for approximately 30% of the country's exports with a mineral production of 40 billion dollars (Brazilian Mining Institute, 2015). In this scenario, as a consequence of mining, the Amazonian ecosystem has been undergoing a constant process of degradation. An important artifice in the exploitation of mineral resources is the rehabilitation and/or recovery of degraded areas. This recovery requires the establishment of degradation indicators and also the quality of the soil associated with its biota, since the Amazonian environment is dynamic, heterogeneous and complex in its physical, chemical and biological characteristics. In this way, this work presupposes that it is possible to characterize the different stages of recovery of tillage floor areas in deactivated cassiterite mines, within the Amazonian forest, in order to evaluate the interactions between the level of biological activity (Serrapilheira Height, Coefficient Metabolic, Basal Breath) and physical soil characteristics (aggregate DMG, Porosity, Total Soil Density, Moisture Content), through canonical correlation analysis. The results present correlations between the groups of indicators. Thus, from the use of the groups defined by canonical correlations, it was possible to identify the response of the set of physical and biological variables to the areas at different stages of recovery.

  1. Report on Influence of Physical and Biological Soil Processes on NO3- Fertilizer

    International Nuclear Information System (INIS)

    Rolston, D.E.

    1981-01-01

    Denitrification of nitrate (NO 3 - ) fertilizer was simulated using a mathematical model. The rate of denitrification was considered to be a function of NO 3 - concentration, available carbon (C) concentration, degree of soil-water saturation, and temperature. Available C concentrations were calculated from initial amounts of soil C and additions of plant residues or animal manure. The consumption of added C in the soil system was assumed to occur in 2 or 3 stages with different rate constants for each stage and C source. A Q 10 value of 2 was used in correcting denitrification rate constants and C consumption constants at two temperatures. Model simulations for denitrification were compared with measured N 2 and N 2 O gas fluxes during nitrate leaching in field plots of Yolo soil at different soil-water content, C additions, soil temperature, and irrigation frequencies

  2. Assessing effects of the entomopathogenic fungus Metarhizium brunneum on soil microbial communities in Agriotes spp. biological pest control.

    Science.gov (United States)

    Mayerhofer, Johanna; Eckard, Sonja; Hartmann, Martin; Grabenweger, Giselher; Widmer, Franco; Leuchtmann, Adrian; Enkerli, Jürg

    2017-10-01

    The release of large quantities of microorganisms to soil for purposes such as pest control or plant growth promotion may affect the indigenous soil microbial communities. In our study, we investigated potential effects of Metarhizium brunneum ART2825 on soil fungi and prokaryota in bulk soil using high-throughput sequencing of ribosomal markers. Different formulations of this strain, and combinations of the fungus with garlic as efficacy-enhancing agent, were tested over 4 months in a pot and a field experiment carried out for biological control of Agriotes spp. in potatoes. A biocontrol effect was observed only in the pot experiment, i.e. the application of FCBK resulted in 77% efficacy. Colony counts combined with genotyping and marker sequence abundance confirmed the successful establishment of the applied strain. Only the formulated applied strain caused small shifts in fungal communities in the pot experiment. Treatment effects were in the same range as the effects caused by barley kernels, the carrier of the FCBK formulation and temporal effects. Garlic treatments and time affected prokaryotic communities. In the field experiment, only spatial differences affected fungal and prokaryotic communities. Our findings suggest that M. brunneum may not adversely affect soil microbial communities. © FEMS 2017.

  3. Influence of green manure in physical and biological properties of soil and productivity in the culture of soybean

    Directory of Open Access Journals (Sweden)

    Ricardo Alves Cardoso

    2014-12-01

    Full Text Available Green manuring is the practice of using plant species in rotation, succession or intercropped with other crops, aiming improvement, maintenance and recovery of physical, chemical and biological soil properties. The objective was to evaluate the influence of different green manures on soil characteristics and productivity of soybean. The experiment was conducted in Maringá (PR in a randomized block design with six treatments and four replications: T1: oat (Avena Sativa, T2: black oat (Avena strigosa, T3: dwarf pigeon pea (Cajanus cajan, T4: radish (Raphanus sativus L., T5: white lupine (Lupinus albus and T6: control (fallow. At the end of the experiment, relations were established between the green manure used for soybean production, the production of biomass, the development of microorganisms and soil bulk density. The data were analyzed with statistical software and means were compared by Tukey test at 5% probability. The coverages provided higher content of dry matter were lupine, black oat and faba bean. Treatments that most influenced the increase of soil microorganisms were lupine, radish and pigeonpea. Regarding productivity, higher values were obtained in treatments with pigeon pea, lupine and oat. The apparent density of the soil, treatment with turnip showed better results.

  4. Biology of main soil formers in the area of radioactive contamination

    International Nuclear Information System (INIS)

    Maksimova, S.L.

    2007-01-01

    Based on the results of our study, we have a conclusion - the decomposer community exposed to irradiation for a long time reacts clearly by a noticeable suppression. Our results also demonstrated that there was a strong relation between decomposition rates and numbers of decomposer fauna present in soil layers. Taking into account the important role of decomposer invertebrates in the development and maintenance of soil structure, and in the incorporation and breakdown of organic residues in the soil, we made conclusion that the reduction of density and biodiversity of decomposer organisms in the contaminated zone produced long term effects on the soil health. (authors)

  5. Soil compaction: alterations in physical, chemical and biological attributes in a fluvic neosoil

    International Nuclear Information System (INIS)

    Viana, Eliane Ferreira

    2004-12-01

    The efficient management of soil proposes the correct utilization of agricultural practices to minimize the loss of structure, compaction, and nutrient losses in the soil, which are the main causes of its degradation. Such concerns reside in the fact that the impact from compaction can also be related to the soil capacity for losing carbon. This effect has strong influence on CO 2 emissions to the atmosphere. On the other hand, induced mutation, a valuable tool for the development of genetic materials, that is tolerant to environmental adversities, can be helpful in the adaptation of crops in compacted soils. This study was conducted to evaluate isolated and combined effects of compaction, water content and organic amendments in soil respiration. Also it investigates the development of cowpea (V. unguiculata, L. Walp] var. IPA 206, in a Fluvic Neosoil, artificially compacted, with different fertilizer materials added (cowdung, NPK, organomineral I, and organomineral II). Also it evaluates the development of cowpea when the seeds were submitted to gamma irradiation ( 60 Co) and cultivated in compacted and non compacted soil, under greenhouse conditions, for 60 days. The isolated addition of spent coffee powder and marine algae to the soil increased the CO 2 evolution from soil, reflecting variations in dynamics of the heterotrophic soil microbiota. CO 2 evolution decreased with the increase in soil density, showing reductions in aeration. The values presented were found to be low in the treatment without addition of these materials (control) and showed them to be significantly increased in the treatments that received such residues, all over the incubation period. Plant height, root length, shoot dry matter production and dry matter of nodules diminished with the increase in soil density. The incorporation of the organomineral mixtures I and II to the artificially compacted soil, showed an increase in plant height, and root length, suggesting the beneficial action

  6. Stimulation of biological N2-fixation to accelerate the microbial remediation of soil contaminated by petroleum hydrocarbons

    International Nuclear Information System (INIS)

    Tereshenko, N.N.; Lushnikov, S.V.

    2005-01-01

    All remediation projects are comprised at least in accelerating the processes of the self-cleaning and self-restoration of biocenose which is led to increasing the functional activity of hydrocarbon-oxidizing microflora (HOM). Some of experts are carefully relate to introducing the commercial cultures of active hydrocarbon-consuming microbes into soils. They are afraid of unpredictable behavior of the cultures in soils. That why the stimulation of metabolic activity of indigenous soil microflora seems to be most preferable. In fact, contamination of soil with low nitrogen capacity by oil spills leads to significant deficient of nitrogen for HOM. Nitrogen content limits the soil self-restoration. Inorganic nitrogen fertilizers are supplied to recover the balance. The study of the microbial destruction of petroleum-hydrocarbons in association with biochemical transformation of nitrogen was carried out in lab and field experiments during 2000-2004. Study showed the activity of HOM correlates with rate of microbial fixing atmospheric nitrogen. Activity of biological N 2 -fixation significantly depends on supplying fertilizers (dose, date and kind). General practice of remediation of hydrocarbon-contaminated soils applies high initial doses of nitrogen-fertilizers (0.5-1 t per ha). Such practice leads to inhibition of N 2 -fixation processes, decreasing rate of oil destruction and loosing nitrogen due to activation of microbial denitrification. In opposition to that, the fractioned and advanced supplying mineral nitrogen fertilizers with aluminosilicate is the cost-effective approach to remediation of hydrocarbon-contaminated soils. Field experiments showed that the approach allows to increase efficiency of treatment up to 70-75% and to decrease operational expenses 2-3 times at least. (authors)

  7. Influence of superabsorbent polymers on the chemical composition of strawberry (Fragaria × ananassa Duch. and biological activity in the soil

    Directory of Open Access Journals (Sweden)

    Mikiciuk Grzegorz

    2015-06-01

    Full Text Available By improving the air and water properties of soils, superabsorbent polymers can affect the increase and improvement of the quality of the yield of berry plants, including strawberries. Their presence in the soil has an influence on its biological activity as related to microorganisms. The aim of the research was to assess the influence of superabsorbent polymers added to the soil on the content of macroelements and sodium in the leaves and fruit of strawberry of the ‘Elsanta’ cultivar and changes in the number of soil bacteria, actinomycetes and fungi. The superabsorbent polymer (AgroHydroGel was used in two doses: 1.8 and 3.6 g dm-3 of soil. The content of phosphorus, potassium, calcium, magnesium and sodium was assessed using the ASA method, while the content of nitrogen and sulphur was assessed by the elemental analysis method (CHNS analyser. The number of microorganisms was assessed with a BacTrac analyser and the coefficient of microorganism development extent (SR was also determined. AgroHydroGel increased the content of nitrogen and potassium in leaves and fruit but did not affect the content of phosphorus, sulphur and sodium. The addition of the superabsorbent at a dose of 3.6 g dm-3 of soil reduced the magnesium content both in the leaves and fruit of the strawberry. AgroHydroGel decreased the content of calcium in the fruit. The use of AgroHydroGel contributed to the expansion of the K ion ratio to other ions, both in the leaves and fruits. We observed a significant increase in the amount of soil bacteria (1.8 g dm-3 dose and no significant influence on actinomycetes and fungi (irrespective of dose used.

  8. Dynamic aspects of soil organic matter and its relationship to the physical properties and fertility of soils

    International Nuclear Information System (INIS)

    Wagner, G.H.

    1980-01-01

    Soil organic matter plays a critical role in determining the physical, chemical, and biological nature of soils. Its dynamic nature is explored with reference to the cycling of C and N in the biosphere. Optimum soil structure is developed under a grass sod, but adequate water stable aggregates can be maintained under proper cultivation to ensure deep root penetration, rapid water infiltration for storage in the rooting zone, and the prevention of surface crusting. Perhaps the most important role of organic material is its prevention of soil erosion by directly stabilizing the soil during the growing season, providing residues for protection between crops, and improving surface aggregation to make the soil less subject to erosion. (author)

  9. 14C dating of charcoal in the soil for the study of biological remount of soil matter and of the colluvium in the formation of ferralitic soils of Sao Paulo state, southern Brazil

    International Nuclear Information System (INIS)

    Gouveia, S.E.M.; Pessenda, L.C.R.

    2000-01-01

    This paper complements a scientific investigation, published in a precedent Compte Rendu, that showed that the burial of charcoal in a oxisol of the Minas Gerais State, southern Brazil, is a result of the biological remount of soil matter removed from deeper parts by the fauna. Such transported material would then constitute the soil layer containing charcoal (generally up to 2 m). The new results obtained at two sites in Sao Paulo State confirm, on the one hand, the role of the fauna in the development of these oxisols and, on the other hand, that colluvium can intervene in the burial of charcoal. (authors)

  10. Roles of biology, chemistry, and physics in soil macroaggregate formation and stabilization

    Science.gov (United States)

    Soil functions or ecosystem services depend on the distribution of macro- (= 0.25 mm) and micro- (< 0.25 mm) aggregates and open space between aggregates. It is the arrangement of the aggregates and pore space which allows air and water movement in and out of soil; reduces compaction; and stimulates...

  11. On-farm impact of cattle slurry manure management on biological soil quality

    NARCIS (Netherlands)

    Goede, de R.G.M.; Brussaard, L.; Akkermans, A.D.L.

    2003-01-01

    The effects of dairy cattle slurry management on soil biota, soil respiration and nitrogen (N) mineralization were evaluated in a farm trial across 12 farms and a field experiment on 2 farms located in a dairy farming area in the north of the Netherlands. The slurry management consisted of slit

  12. Biopiles - demonstration of cost effective biological remediation of furnace oil contaminated soils

    International Nuclear Information System (INIS)

    Kirchmair, G.A.

    1998-01-01

    Approximately 900 tonnes of soil was contaminated at a rural manufacturing facility near Collingwood, Ontario, when a 9000 litre underground furnace oil storage tank sprang a leak. The contaminated soil was excavated and stockpiled at the site and the leak was repaired. The Ontario Ministry of the Environment ordered that the owner treat the soil to the proper criteria or have the soil removed from the site and properly disposed of at a licensed landfill facility. Barenco was hired to treat the soil. Bioremediation began in December 1994 with the creation of nine above-ground biopiles which were constructed through the addition of nutrients (manure from a local farmer). Piping for air injection and treatment were located throughout the biopiles. The biopiles were then covered with 6 mil black HDPE plastic. The progress of the bioremediation was monitored regularly through measurement of carbon dioxide and oxygen concentrations in the biopiles. By October 1995, the soil was treated to within the appropriate criteria. In 10 months, the total petroleum hydrocarbon concentrations in the polluted soil were reduced from an average of 2690 ppm to 275 ppm. This simple and cost effective approach can also be used to remediate soils impacted with diesel fuels

  13. FATE OF PAH COMPOUNDS IN TWO SOIL TYPES: INFLUENCE OF VOLATILIZATION, ABIOTIC LOSS, AND BIOLOGICAL ACTIVITY

    Science.gov (United States)

    The fate of 14 polycyclic aromatic hydrocarbon (PAH) compounds was evaluated with regard to interphase transfer potential and mechanisms of treatment in soil under unsaturated conditions. Volatilization and abiotic and biotic fate of the PAHs were determined using two soils not p...

  14. Plant biomass increase linked to biological activity in soils amended with sewage sludge compost

    International Nuclear Information System (INIS)

    Ibanez-Burgos, A.; Lopez-Lopez, G.; Vera, J.; Rovira, J. M.; Reolid, C.; Sastre-Conde, I.

    2009-01-01

    Sewage sludge compost application to almond tree plantations presents a potential management alternative to combat soil mismanagement in Mediterranean areas where almonds are grown. this practice could also be used to restore vegetable biomass to soils which are not fertile enough to support other crops, as well as to fight climatic change. (Author)

  15. Plant biomass increase linked to biological activity in soils amended with sewage sludge compost

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez-Burgos, A.; Lopez-Lopez, G.; Vera, J.; Rovira, J. M.; Reolid, C.; Sastre-Conde, I.

    2009-07-01

    Sewage sludge compost application to almond tree plantations presents a potential management alternative to combat soil mismanagement in Mediterranean areas where almonds are grown. this practice could also be used to restore vegetable biomass to soils which are not fertile enough to support other crops, as well as to fight climatic change. (Author)

  16. A Synthetic Biology Architecture to Detoxify and Enrich Mars Soil for Agriculture

    Data.gov (United States)

    National Aeronautics and Space Administration — Although the theoretical case for space biological engineering is convincing, since recent studies on the use of biology in space showed substantial payload...

  17. Soil variability and effectiveness of soil and water conservation in the Sahel.

    NARCIS (Netherlands)

    Hien, F.G.; Rietkerk, M.; Stroosnijder, L.

    1997-01-01

    Sahelian sylvopastoral lands often degrade into bare and crusted areas where regeneration of soil and vegetation is impossible in the short term unless soil and water conservation measures are implemented. Five combinations of tillage with and without mulch on three crust type/soil type combinations

  18. Use of the reference organism Eisenia foetida to investigate bioaccumulation and biological effects following contamination of soil by uranium

    International Nuclear Information System (INIS)

    Giovanetti, A.; Cozzella, M.L.; Basso, E.; Ninova, P.; Fesenko, S.; Sansone, U.

    2006-01-01

    Full text of publication follows: The use of reference organisms for radiological assessments on non -human species is an integral part of the current systemic approach for the management of radiation effects in the environment. The reference organisms approach allows the evaluation of radiological impact on the environment taking into account relationships among ambient radionuclide activity concentrations, dose and expected adverse biological effects. Four broad categories of biological damages are included: mortality, morbidity, DNA damage and reproductive failure. Earthworms are one of the most important biotic components in the soil, they are commonly used in studies of toxicity and they are included in the list of the reference organisms suggested by International (ICRP) and national organisations. However, up to now, no adequate results have been obtained for earthworms allowing the identification of the dose-response relationship, essentially for the contamination scenarios where radionuclide can provide both radiation and chemical impact. Uranium (U) is a naturally occurring heavy metal. Recently there has been public concern on the presence in the environment of depleted uranium (DU), a by-product of the process used to enrich natural uranium ore for use in nuclear reactors and in nuclear weapons. The presence of uranium in soil could lead to both toxic and radiation impact and it is difficult to distinguish the different impacts and their contribution to possible biological effects. European Union, OECD and FAO have selected the earthworms Eisenia for testing soil toxicity because it is an organism that can be easily cultured in the laboratory, an extensive database is available, and it feeds at the soil surface level. The prime objective of the present study was to evaluate the possible use of Eisenia foetida as a bio-marker of U environmental impact. Four groups of six sexually mature Eisenia foetida were maintained in the dark at 21 deg. C in Petri

  19. Short-Term Effect of Vermicompost Application on Biological Properties of an Alkaline Soil with High Lime Content from Mediterranean Region of Turkey

    Science.gov (United States)

    Uz, Ilker; Tavali, Ismail Emrah

    2014-01-01

    This study was conducted to investigate direct short-term impact of vermicompost on some soil biological properties by monitoring changes after addition of vermicompost as compared to farmyard manure in an alkaline soil with high lime content from semiarid Mediterranean region of Turkey. For this purpose, mixtures of soil and organic fertilizers in different doses were incubated under greenhouse condition. Soil samples collected in regular intervals were analyzed for biological parameters including dehydrogenase, β-glucosidase, urease, alkaline phosphatase activities, and total number of aerobic mesophilic bacteria. Even though soil dehydrogenase activity appeared to be dose-independent based on overall evaluation, organic amendments were found to elevate dehydrogenase activity when sampling periods are evaluated individually. β-glucosidase, urease, alkaline phosphatase activity, and aerobic mesophilic bacterial numbers in vermicompost treatments fluctuated but remained significantly above the control. A slight but statistically significant difference was detected between organic amendments in terms of urease activity. Vermicompost appeared to more significantly increase bacterial number in soil. Clearly, vermicompost has a potential to be used as an alternative to farmyard manure to improve and maintain soil biological activity in alkaline calcareous soils from the Mediterranean region of Turkey. Further studies are needed to assess its full potential for these soils. PMID:25254238

  20. Growth of soil algae and cyanobacteria on gold mine tailings material

    Directory of Open Access Journals (Sweden)

    Tanya Seiderer

    2017-11-01

    Full Text Available The goal of revegetation of gold mine tailings storage facilities is to reduce aeolian pollution, nutrient leaching and erosion caused by exposure to wind and water. The establishment of biological soil crusts may prove to be a more cost-effective way to reach the same goal and the aim of this study was therefore to determine if it is possible to establish algae and cyanobacteria on gold mine tailings. Different treatments of Chlamydomonas, Microcoleus and Nostoc were inoculated on gold mine tailings in controlled conditions and algal growth was measured on all of the treatments after 6 weeks. Nostoc treatments had the highest chlorophyll-a concentrations and produced a surface crust, while Chlamydomonas treatments penetrated the tailings material and provided the strongest crust. The results were promising but more research is necessary to determine the best organism, or combination of organisms, to colonise mine tailings and to eventually produce biological crusts. Significance: Determination of the best organisms to colonise mine tailings and to produce biological crusts for the revegetation of gold mine tailings storage facilities.

  1. About chemical and biological stimulation of bioleaching of 90Sr from different types of soil

    International Nuclear Information System (INIS)

    Buravlev, E.P.; Trishin, V.V.; Svyatun, O.V.; Berlizov, A.N.; Kim, In.S.; Ivanov, V.N.

    2000-01-01

    The results of investigation carried out in the frame of international cooperation between the NASU and KOSEF on the creation of effective methods of purification of radioactively polluted soil were performed. The influence of methanogenic, surface-reducing, nitrifying and thiobacilli and also their joint activity with different chemical ingredients on bioleaching of 90 Sr from typical South Korea red soil,artificially radioactively polluted by 90 Sr, and technogenically polluted by the radionuclides from influenced zone of ChNPP was studied, The presence of the largest effect of thiobacilli on soil was shown

  2. Soil-biological, soil-chemical and soil-physical parameters along a pollutant gradient on grassland sites in the vicinity o Brixlegg (Tyrol) - a pilot project

    International Nuclear Information System (INIS)

    Pohla, H.; Palzenberger, M.; Krassnigg, F.; Kandeler, E.; Schwarz, S.; Kasperowski, E.

    1992-01-01

    It was the main aim of this pilot project to check the indicator value of soil organisms by means of distinct pollutant gradients - heavy metals, organic compounds (PCB, dioxins) -. On the basis of available results (1/2/3/), 4 grassland sites at increasing distances from a local emission source (copper production from scrap metal) were selected. Physical and chemical analyses as well as the quantification of habitat structures were used for the characterization of the sites. The following analyses were carried out accompanyingly: The performances of soil microorganisms under pollutant load, the accumulation of pollutants, and the structures of plants and animal communities (macro, meso and microfauna). The investigation area and the examined parameters are introduced, as well as first result on soil chemistry and enzymatics as well as for the accumulation of heavy metals in an earthworm species are introduced. (orig.) [de

  3. CARBOHYDRATE USE AND ASSIMILATION BY LITTER AND SOIL FUNGI ASSESSED BY CARBON ISOTOPES AND BIOLOG ASSAYS

    Science.gov (United States)

    Soil fungi are integral to decomposition in forests, yet identification of probable functional roles of different taxa is problematic. Here, we compared carbohydrate assimilation patterns derived from stable isotope analyses on cultures with those produced from cultures on Biolo...

  4. The isolation, enumeration, and characterization of Rhizobium bacteria of the soil in Wamena Biological Garden

    Directory of Open Access Journals (Sweden)

    SRI PURWANINGSIH

    2005-04-01

    Full Text Available The eleven soil samples have been isolated and characterized. The aims of the study were to get the pure culture and some data which described about enumeration and especially their characters in relation to the acids and bases reaction in their growth. The isolation of the bacteria use Yeast Extract Mannitol Agar medium (YEMA while the characterization by using YEMA medium mixed with Brom Thymol Blue and Congo Red indicators respectively. The results showed that eighteen isolates have been isolated which consisted of three low growing and fifteen fast growing bacteria. Two isolates were not indicated Rhizobium and sixteen were Rhizobium. Density of Rhizobium enumeration was varied which related to soil organic matter content. The enumeration bacteria in YEMA medium were in the range of 0.6 x 105 and 11.6 x 105 CFU /g soil. The highest population was found in soil sample of Wieb vegetation.

  5. Potential Use of Tracer Methods, Especially Autoradiography, in the Study of the Relation of Herbicides to Soil Biology

    Energy Technology Data Exchange (ETDEWEB)

    Grossbard, E. [Grassland Research Institute, Hurley, Maidenhead, Berks (United Kingdom)

    1966-05-15

    Several tracer methods, designed originally for the study of general soil processes, are described. Their possible adaptation to investigations of the interaction of herbicides with soil biology (especially the soil microflora) is discussed. Rapid disposal of the herbicide-treated vegetation before replanting (minimal tillage) is essential. In comparing the efficiency of herbicidal destruction of vegetation with conventional ploughing, and also when evaluating the effect of various herbicides on the rate of decay of the treated crops, a method is required to measure the rate of the microbial decomposition of the plant residues. A technique based on autoradiography is described which makes possible the study of the progressive decay of herbage grasses and rye uniformly labelled with carbon-14, placed on the surface of soil and incubated for various periods of time. Photoelectric measurements of the density of images of autoradiographs prepared before the start of the experiment and at intervals during incubation show a statistically significant decrease in density with time of incubation. This progressive loss of carbon is an estimate of the rate of decomposition of the residues. The utilization of breakdown products of herbicides by micro-organisms has been demonstrated in pure culture using labelled herbicides but not directly in the soil. A method based on the stripping film technique demonstrates the incorporation of carbon-14 atoms into the cell material of fungi which decomposed {sup 14}C-labelled plant residues mixed with soil. This technique could be adapted to study the uptake of labelled atoms after the microbial decomposition of radioactive herbicides in the soil. Herbicides inhibit and under,certain conditions may also stimulate the growth of micro-organisms in the soil. The evolution of CO{sub 2} is frequently used as an index of microbial activity. It is, however, also a function of the carbon content of the soil. Soils not treated with herbicides will

  6. Influence of Soils, Riparian Zones, and Hydrology on Nutrients, Herbicides, and Biological Relations in Midwestern Agricultural Streams

    Science.gov (United States)

    Porter, S.

    2001-12-01

    Chemical, biological, and habitat conditions were characterized in 70 streams in the upper Mississippi River basin during August 1997, as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The study was designed to evaluate algal and macroinvertebrate responses to high agricultural intensity in relation to nonpoint sources of nutrients and herbicides, characteristics of basin soils, wooded-riparian vegetation, and hydrology. Concentrations and forms of nutrients, herbicides and their metabolites, and seston constituents varied significantly with regional differences in soil properties, ground and surface water relations, density of riparian trees, and precedent rainfall-runoff conditions. Dissolved nitrate concentrations were relatively low in streams with high algal productivity; however, nitrate concentrations increased with basin water yield, which was associated with the regional distribution of rainfall during the month prior to the study. Stream productivity and respiration were positively correlated with seston (phytoplankton) chlorophyll concentrations, which were significantly larger in streams in areas with poorly drained soils and low riparian-tree density. Concentrations of dissolved phosphorus were low in streams where periphyton biomass was high. Periphyton biomass was relatively larger in streams with clear water and low abundance of macroinvertebrates that consume algae. Periphyton biomass decreased rapidly with modest increases in the abundance of scrapers such as snails and certain mayfly taxa. Differences in dissolved oxygen, organic carbon, stream velocity, and precedent hydrologic conditions explained much of the variance in macroinvertebrate community structure. The overall number of macroinvertebrate species and number of mayfly, caddisfly, and stonefly (EPT) taxa that are sensitive to organic enrichment were largest in streams with moderate periphyton biomass, in areas with moderately-well drained soils

  7. Chemico-biological treatment of polluted soils by polychorinated biphenyls; Tratamiento integrado quimico-biologico de suelos contaminados por bifenilos policlorados

    Energy Technology Data Exchange (ETDEWEB)

    Manzano Quinones, M. A.

    2001-07-01

    In this work a study of biological and chemical treatment of polychlorinated biphenyls (PCBs) in soil has been done. The experiments have been carried out in pilot scale reactors and the results obtained showed 98% elimination and a high mineralization of PCBs employing a Integrated Chemical-Biological Treatment. (Author) 12 refs.

  8. [The influence of variable and constant magnetic fields on biota and biological activity of ordinary chernozem soils].

    Science.gov (United States)

    Denisova, T V; Kazeev, K Sh

    2007-01-01

    In model experiments on influence variable magnetic fields of industrial frequency (50 Hz) an induction of 1500 and of 6000 mkTl and the constant magnetic field an induction of 6000 mkTl and of 15000 mkTl during 5 days of exposure on biological properties of chernozem ordinary is shown, that the soil microflora is more sensitive to magnetic fields, than enzymes activity. Bacteria are more sensitive, than microscopic mushrooms. Dehydrogenase it is steady against influence of all variants. Constant magnetic field by the induction of 15000 mkTl rendered practically identical authentic overwhelming influence on catalase and saccharase activity - on 51 and 47% accordingly.

  9. Marine biominerals: perspectives and challenges for polymetallic nodules and crusts.

    Science.gov (United States)

    Wang, Xiaohong; Müller, Werner E G

    2009-06-01

    Deep sea minerals in polymetallic nodules, crusts and hydrothermal vents are not only formed by mineralization but also by biologically driven processes involving microorganisms (biomineralization). Within the nodules, free-living and biofilm-forming bacteria provide the matrix for manganese deposition, and in cobalt-rich crusts, coccolithophores represent the dominant organisms that act as bio-seeds for an initial manganese deposition. These (bio)minerals are economically important: manganese is an important alloying component and cobalt forms part of special steels in addition to being used, along with other rare metals, in plasma screens, hard-disk magnets and hybrid car motors. Recent progress in our understanding of the participation of the organic matrices in the enrichment of these metals might provide the basis for feasibility studies of biotechnological applications.

  10. Soil

    International Nuclear Information System (INIS)

    Freudenschuss, A.; Huber, S.; Riss, A.; Schwarz, S.; Tulipan, M.

    2002-01-01

    Environmental soil surveys in each province of Austria have been performed, soils of about 5,000 sites were described and analyzed for nutrients and pollutants, the majority of these data are recorded in the soil information system of Austria (BORIS) soil database, http://www.ubavie.gv.at/umweltsituation/boden/boris), which also contains a soil map of Austria, data from 30 specific investigations mainly in areas with industry and results from the Austria - wide cesium investigation. With respect to the environmental state of soils a short discussion is given, including two geographical charts, one showing which sites have soil data (2001) and the other the cadmium distribution in top soils according land use (forest, grassland, arable land, others). Information related to the soil erosion, Corine land cover (Europe-wide land cover database), evaluation of pollutants in soils (reference values of As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Se, Pb, Tl, Va, Zn, AOX, PAH, PCB, PCDD/pcdf, dioxin), and relevant Austrian and European standards and regulations is provided. Figs. 2, Tables 4. (nevyjel)

  11. Biological soil attributes in oilseed crops irrigated with oilfield produced water in the semi-arid region

    Directory of Open Access Journals (Sweden)

    Ana Clarice Melo Azevedo de Meneses

    Full Text Available ABSTRACT Wastewater from oil is the main residue of the oil industry. Studies have shown that wastewater, or produced water, can be treated and used as an alternative source for the irrigation of oilseed crops. The aim of this work was to evaluate the effect of treated produced water on the biological properties of soil cultivated with the castor bean cv. BRS Energy and the sunflower cv. BRS 321 respectively, for two and three successive cycles of grain production. The first cycle in the sunflower and castor bean corresponds to the dry season and the second cycle to the rainy season. The third crop cycle in the sunflower relates to the dry season. The research was carried out from August 2012 to October 2013, in the town of Aracati, in the State of Ceará (Brazil, where both crops were submitted to irrigation with filtered produced water (FPW, produced water treated by reverse osmosis (OPW, or groundwater water from the Açu aquifer (ACW, and to no irrigation (RFD. The treatments, with three replications, were evaluated during the periods of pre-cultivation and plant reproduction for soil respiration (Rs, total organic carbon (TOC and the population density of bacteria (Bact and filamentous fungi (Fung in the soil. In the sunflower crop, these soil attributes are sensitive to the irrigation water used. Irrigation of the castor bean affects soil respiration. Under the conditions of this study, irrigation with FPW may be a short-term alternative in the castor bean and sunflower crops.

  12. Hazard evaluation of soil contaminants from an abandoned oil refinery site with chemical and biological assays

    International Nuclear Information System (INIS)

    Ramanathan, A.; Yates, C.W.; Burks, S.L.

    1993-01-01

    The phytotoxic characteristics of soil and leachates of soil from an abandoned oil refinery site were evaluated with rice (Oryza sativa L.) seed germinations and root elongation assays. Toxicity of soil leachates to aquatic animals was determined with acute and martial chronic toxicity tests with Ceriodaphnia dubia, fathead minnows, and Microtox reg-sign. Soil samples from uncontaminated (control) and selected contaminated areas within the old refinery were extracted with Toxic Characteristics Leachate Procedure (TCLP), an aqueous procedure and a supercritical carbon dioxide method. Aqueous extracts of soil from the oil leaded gasoline storage area exhibited greatest effects in all tests. Aqueous extracts from this site also caused a significant reduction in rice root development. Supercritical carbon dioxide extraction proved to be a quick and non-toxic procedure for isolating non-polar organics for assay with aquatic toxicity tests. Subsequent supercritical extracts collected in solvent can help characterize the class of toxicants through HPLC and Gas Chromatography. The toxic constituents were characterized with a Toxicity Identification/Toxicity Reduction Evaluation protocol to fractionate the contaminants into conventional non-polar organics, weak acids, base-neutrals, or heavy metals for subsequent analysis

  13. Effect of thicker oceanic crust in the Archaean on the growth of continental crust through time

    International Nuclear Information System (INIS)

    Wilks, M.E.

    1988-01-01

    Present crustal evolution models fail to account for the generation of the large volume of continental crust in the required time intervals. All Archaean plate tectonic models, whether invoking faster spreading rates, similar to today's spreading rates, or longer ridge lengths, essentially propose that continental crust has grown by island arc accretion due to the subduction of oceanic crust. The petrological differences that characterize the Archaean from later terrains result from the subduction of hotter oceanic crust into a hotter mantle. If the oceanic crust was appreciably thicker in the Archaean, as geothermal models would indicate, this thicker crust is surely going to have an effect on tectonic processes. A more valid approach is to compare the possible styles of convergence of thick oceanic crust with modern convergence zones. The best modern analog occurs where thick continental crust is colliding with thick continental crust. Oceanic crustal collision on the scale of the present-day Himalayan continental collision zone may have been a frequent occurrence in the Archaean, resulting in extensive partial melting of the hydrous underthrust oceanic crust to produce voluminous tonalite melts, leaving a depleted stabilized basic residuum. Present-day island arc accretion may not have been the dominant mechanism for the growth of the early Archaean crust

  14. Soils

    International Nuclear Information System (INIS)

    Freudenschuss, A.; Huber, S.; Riss, A.; Schwarz, S.; Tulipan, M.

    2001-01-01

    For Austria there exists a comprehensive soil data collection, integrated in a GIS (geographical information system). The content values of pollutants (cadmium, mercury, lead, copper, mercury, radio-cesium) are given in geographical charts and in tables by regions and by type of soil (forests, agriculture, greenland, others) for the whole area of Austria. Erosion effects are studied for the Austrian region. Legal regulations and measures for an effective soil protection, reduction of soil degradation and sustainable development in Austria and the European Union are discussed. (a.n.)

  15. Millennial-scale ocean acidification and late Quaternary decline of cryptic bacterial crusts in tropical reefs.

    Science.gov (United States)

    Riding, R; Liang, L; Braga, J C

    2014-09-01

    Ocean acidification by atmospheric carbon dioxide has increased almost continuously since the last glacial maximum (LGM), 21,000 years ago. It is expected to impair tropical reef development, but effects on reefs at the present day and in the recent past have proved difficult to evaluate. We present evidence that acidification has already significantly reduced the formation of calcified bacterial crusts in tropical reefs. Unlike major reef builders such as coralline algae and corals that more closely control their calcification, bacterial calcification is very sensitive to ambient changes in carbonate chemistry. Bacterial crusts in reef cavities have declined in thickness over the past 14,000 years with largest reduction occurring 12,000-10,000 years ago. We interpret this as an early effect of deglacial ocean acidification on reef calcification and infer that similar crusts were likely to have been thicker when seawater carbonate saturation was increased during earlier glacial intervals, and thinner during interglacials. These changes in crust thickness could have substantially affected reef development over glacial cycles, as rigid crusts significantly strengthen framework and their reduction would have increased the susceptibility of reefs to biological and physical erosion. Bacterial crust decline reveals previously unrecognized millennial-scale acidification effects on tropical reefs. This directs attention to the role of crusts in reef formation and the ability of bioinduced calcification to reflect changes in seawater chemistry. It also provides a long-term context for assessing anticipated anthropogenic effects. © 2014 John Wiley & Sons Ltd.

  16. INFLUENCE OF VERMICOMPOST ON THE PHYSICO-CHEMICAL AND BIOLOGICAL PROPERTIES IN DIFFERENT TYPES OF SOIL ALONG WITH YIELD AND QUALITY OF THE PULSE CROP-BLACKGRAM

    Directory of Open Access Journals (Sweden)

    K. Parthasarathi, M. Balamurugan, L. S. Ranganathan

    2008-01-01

    Full Text Available Field experiments were conducted during 2002-2003 on clay loam, sandy loam and red loam soil at Sivapuri, Chidambaram, Tamil Nadu, to evaluate the efficacy of vermicompost on the physico-chemical and biological characteristics of the soils and on the yield and nutrient content of blackgram - Vigna mungo, in comparison to inorganic fertilizers nitrogen, phosphorous, potassium. Vermicompost had increased the pore space, reduced particle and bulk density, increased water holding capacity, cation exchange capacity, reduced pH and electrical conductivity, increased organic carbon content, available nitrogen, phosphorous, potassium and microbial population and activity in all the soil types, particularly clay loam. The yield and quality (protein and sugar content in seed of blackgram was enhanced in soils, particularly clay loam soil. On the contrary, the application of inorganic fertilizers has resulted in reduced porosity, compaction of soil, reduced carbon and reduced microbial activity.

  17. Corrosion of bare carbon steel as a passive sensor to assess moisture availability for biological activity in Atacama Desert soils.

    Science.gov (United States)

    Cáceres, Luis; Davila, Alfonso F; Soliz, Alvaro; Saldivia, Jessica

    2018-02-28

    Here we consider that the corrosion of polished bared metal coupons can be used as a passive sensor to detect or identify the lower limit of water availability suitable for biological activity in Atacama Desert soils or solid substrates. For this purpose, carbon steel coupons were deposited at selected sites along a west-east transect and removed at predetermined times for morphological inspection. The advantage of this procedure is that the attributes of the oxide layer (corrosion extent, morphology and oxide phases) can be considered as a fingerprint of the atmospheric moisture history at a given time interval. Two types of coupons were used, long rectangular shaped ones that were half-buried in a vertical position, and square shaped ones that were deposited on the soil surface. The morphological attributes observed by SEM inspection were found to correlate to the so-called humectation time which is determined from local meteorological parameters. The main finding was that the decreasing trend of atmospheric moisture along the transect was closely related to corrosion behaviour and water soil penetration. For instance, at the coastal site oxide phases formed on the coupon surface rapidly evolve into well-crystallized species, while at the driest inland site Lomas Bayas only amorphous oxide was observed on the coupons.

  18. Corrosion of Bare Carbon Steel as a Passive Sensor to Assess Moisture Availability for Biological Activity in Atacama Desert Soils

    Science.gov (United States)

    Caceres, Luis; Davila, Alfonso F.; Soliz, Alvaro; Saldivia, Jessica

    2018-01-01

    In this work we suggest the corrosion of polished bared metal coupons as a passive sensor to detect or identify the lower limit of water availability that could be suitable for biological activity in the Atacama Desert on soil or solid substrates. For this purpose, carbon steel coupons were deposited in selected sites along a west-east transect and removed at predetermined times for morphological inspection. The advantage of this procedure is that the attributes of the oxide layer (corrosion extent, morphology and oxide phases) can be considered as a fingerprint of the atmospheric moisture history at a given time interval. Two types of coupons were used, a long rectangular shape that are half-buried in a vertical position, and square shape that are deposited on the soil surface. The morphological attributes observed by SEM inspection is correlated to the so-called humectation time which is determined from local meteorological parameters. The main result is that the decreasing trend of atmospheric moisture along the transect is closely related to corrosion behavior and water soil penetration. For instance, while in the coastal site oxide phases formed on the coupon surface rapidly evolve to well- crystallized species, in the driest inland site Lomas Bayas only amorphous oxide is observed.

  19. Impact of soil salinity on the plant-growth – promoting and biological control abilities of root associated bacteria

    Directory of Open Access Journals (Sweden)

    Dilfuza Egamberdieva

    2017-11-01

    Full Text Available The effectiveness of plant growth – promoting bacteria is variable under different biotic and abiotic conditions. Abiotic factors may negatively affect the beneficial properties and efficiency of the introduced PGPR inoculants. The aim of this study was to evaluate the effect of plant growth – promoting rhizobacteria on plant growth and on the control of foot and root rot of tomatoes caused by Fusarium solani under different soil salinity conditions. Among the five tested strains, only Pseudomonas chlororaphis TSAU13, and Pseudomonas extremorientalis TSAU20 were able to stimulate plant growth and act as biological controls of foot and root rot disease of tomato. The soil salinity did not negatively affect the beneficial impacts of these strains, as they were able to colonize and survive on the roots of tomato plants under both saline and non-saline soil conditions. The improved plant height and fruit yield of tomato was also observed for plants inoculated with P. extremorientalis TSAU20. Our results indicated that, saline condition is not crucial factor in obtaining good performance with respect to the plant growth stimulating and biocontrol abilities of PGPR strains. The bacterial inoculant also enhanced antioxidant enzymes activities thereby preventing ROS induced oxidative damage in plants, and the proline concentrations in plant tissue that play an important role in plant stress tolerance.

  20. [Effect of mineral N fertilizer reduction and organic fertilizer substitution on soil biological properties and aggregate characteristics in drip-irrigated cotton field.

    Science.gov (United States)

    Li, Rui; Tai, Rui; Wang, Dan; Chu, Gui-Xin

    2017-10-01

    A four year field study was conducted to determine how soil biological properties and soil aggregate stability changed when organic fertilizer and biofertilizer were used to reduce chemical fertilizer application to a drip irrigated cotton field. The study consisted of six fertilization treatments: unfertilized (CK); chemical fertilizer (CF, 300 kg N·hm -2 ; 90 kg P2O5 · hm -2 , 60 kg K2 O·hm -2 ); 80% CF plus 3000 kg·hm -2 organic fertilizer (80%CF+OF); 60% CF plus 6000 kg·hm -2 organic fertilizer (60%CF+OF); 80% CF plus 3000 kg·hm -2 biofertilizer (80%CF+BF); and 60% CF plus 6000 kg·hm -2 biofertilizer (60%CF+BF). The relationships among soil organic C, soil biological properties, and soil aggregate size distribution were determined. The results showed that organic fertilizer and biofertilizer both significantly increased soil enzyme activities. Compared with CF, the biofertilizer treatments increased urease activity by 55.6%-84.0%, alkaline phosphatise activity by 53.1%-74.0%, invertase activity by 15.1%-38.0%, β-glucosidase activity by 38.2%-68.0%, polyphenoloxidase activity by 29.6%-52.0%, and arylsulfatase activity by 35.4%-58.9%. Soil enzyme activity increased as the amount of organic fertilizer and biofertilizer increased (i.e., 60%CF+OF > 80%CF+OF, 60%CF+BF > 80%CF+BF). Soil basal respiration decreased significantly in the order BF > OF > CF > CK. Soil microbial biomass C and N were 22.3% and 43.5% greater, respectively, in 60%CF+BF than in CF. The microbial biomass C:N was significantly lower in 60%CF+BF than in CF. The organic fertilizer and the biofertilizer both improved soil aggregate structure. Soil mass in the >0.25 mm fraction was 7.1% greater in 80%CF+OF and 8.0% greater in (60%CF+OF) than in CF. The geometric mean diameter was 9.2% greater in 80%CF+BF than in 80%CF+OF. Redundancy analysis and cluster analysis both demonstrated that soil aggregate structure and biological activities increased when organic fertilizer and biofertilizer were

  1. Biological leaching of heavy metals from a contaminated soil by Aspergillus niger

    International Nuclear Information System (INIS)

    Ren Wanxia; Li Peijun; Geng Yong; Li Xiaojun

    2009-01-01

    Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.

  2. Biological leaching of heavy metals from a contaminated soil by Aspergillus niger

    Energy Technology Data Exchange (ETDEWEB)

    Ren Wanxia, E-mail: ren_laura@163.com [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Li Peijun, E-mail: lipeijun@iae.ac.cn [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Geng Yong; Li Xiaojun [Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2009-08-15

    Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils.

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

    Directory of Open Access Journals (Sweden)

    Elham Ghaheri

    2014-04-01

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

  4. Earthworms enhance soil health and may also assist in improving biological insect pest suppression in pecans

    Science.gov (United States)

    Prior research indicated that earthworms may serve as phoretic hosts to entomopathogenic nematodes. Therefore, we hypothesized that biocontrol efficacy of entomopathogenic nematodes could be enhanced in the presence of earthworms based on increased nematode dispersal through the soil. We also hypo...

  5. Polybrominated diphenyl ethers in water, sediment, soil, and biological samples from different industrial areas in Zhejiang, China

    International Nuclear Information System (INIS)

    Wang, Junxia; Lin, Zhenkun; Lin, Kuangfei; Wang, Chunyan; Zhang, Wei; Cui, Changyuan; Lin, Junda; Dong, Qiaoxiang; Huang, Changjiang

    2011-01-01

    Highlights: ► We examined PBDE concentrations in various matrices from different industrial areas. ► Elevated PBDE levels were found in areas with low-voltage electrical manufactures. ► Areas with e-waste recycling activities also had higher PBDE concentrations. ► PBDE content and composition in water samples varied from one area to another. ► PBDE composition in sediment/soil and biological samples was predominated by BDE-209. - Abstract: Polybrominated diphenyl ethers (PBDEs) have been used extensively in electrical and electronic products, but little is known about their distribution in the environment surrounding the manufacturing factories. This study reports PBDE contamination in various matrices from the location (Liushi, Zhejiang province) that produces more than 70% of the low-voltage electrical appliances in China. Additionally, PBDE contamination was compared with other industries such as the e-waste recycling business (Fengjiang) in the same region. Specifically, we measured seven PBDE congeners (BDEs – 47, 99, 100, 153, 154, 183, and 209) in water, sediment, soil, plant, and animal tissues from four different areas in this region. The present study revealed elevated PBDE concentrations in all matrices collected from Liushi and Fengjiang in comparison with highly industrialized areas without significant PBDE contamination sources. In water samples, there were large variations of PBDE content and composition across different areas. In sediment/soil and biological samples, BDE-209 was the predominant congener and this could be due to the abundant usage of deca-BDE mixtures in China. Our findings provide the very first data on PBDE contamination in the local environments surrounding the electronics industry, and also reveal widespread PBDE contamination in highly industrialized coastal regions of China.

  6. Polybrominated diphenyl ethers in water, sediment, soil, and biological samples from different industrial areas in Zhejiang, China

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Junxia; Lin, Zhenkun [Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, Institute of Watershed Science and Environmental Ecology, Wenzhou Medical College, Wenzhou 325035 (China); Lin, Kuangfei [School of Resources and Environmental Engineering, East China University of Science and Technology/State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, Shanghai 200237 (China); Wang, Chunyan [Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, Institute of Watershed Science and Environmental Ecology, Wenzhou Medical College, Wenzhou 325035 (China); Zhang, Wei [School of Resources and Environmental Engineering, East China University of Science and Technology/State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, Shanghai 200237 (China); Cui, Changyuan [Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, Institute of Watershed Science and Environmental Ecology, Wenzhou Medical College, Wenzhou 325035 (China); Lin, Junda [Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Dong, Qiaoxiang, E-mail: dqxdong@163.com [Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, Institute of Watershed Science and Environmental Ecology, Wenzhou Medical College, Wenzhou 325035 (China); Huang, Changjiang, E-mail: cjhuang5711@163.com [Zhejiang Provincial Key Lab for Technology and Application of Model Organisms, Institute of Watershed Science and Environmental Ecology, Wenzhou Medical College, Wenzhou 325035 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We examined PBDE concentrations in various matrices from different industrial areas. Black-Right-Pointing-Pointer Elevated PBDE levels were found in areas with low-voltage electrical manufactures. Black-Right-Pointing-Pointer Areas with e-waste recycling activities also had higher PBDE concentrations. Black-Right-Pointing-Pointer PBDE content and composition in water samples varied from one area to another. Black-Right-Pointing-Pointer PBDE composition in sediment/soil and biological samples was predominated by BDE-209. - Abstract: Polybrominated diphenyl ethers (PBDEs) have been used extensively in electrical and electronic products, but little is known about their distribution in the environment surrounding the manufacturing factories. This study reports PBDE contamination in various matrices from the location (Liushi, Zhejiang province) that produces more than 70% of the low-voltage electrical appliances in China. Additionally, PBDE contamination was compared with other industries such as the e-waste recycling business (Fengjiang) in the same region. Specifically, we measured seven PBDE congeners (BDEs - 47, 99, 100, 153, 154, 183, and 209) in water, sediment, soil, plant, and animal tissues from four different areas in this region. The present study revealed elevated PBDE concentrations in all matrices collected from Liushi and Fengjiang in comparison with highly industrialized areas without significant PBDE contamination sources. In water samples, there were large variations of PBDE content and composition across different areas. In sediment/soil and biological samples, BDE-209 was the predominant congener and this could be due to the abundant usage of deca-BDE mixtures in China. Our findings provide the very first data on PBDE contamination in the local environments surrounding the electronics industry, and also reveal widespread PBDE contamination in highly industrialized coastal regions of China.

  7. Persistence and degradation of pesticide residues in different agricultural soils, related to biological activity. Part of a coordinated programme on isotopic-tracer-aided studies of agrochemical residue - soil biota interactions

    International Nuclear Information System (INIS)

    Flores-Ruegg, E.

    1982-07-01

    Laboratory studies and small-scale field experiments were conducted involving pesticides extensively used in agricultural practice in Brazil (the insecticides aldrin, carbaryl and parathion, and the fungicides carbendazim and metalaxyl) with emphasis on biological activity and soil organic matter content. The ability of fungi isolated from soils of southern, centre and northern regions of Brazil to degrade 14 C-aldrin and its metabolites was assayed in culture growth medium. Results showed that the microorganism Penicilium sp. was able to metabolize the parent compound or one of its metabolites added to the medium. Field studies performed with soils packed into PVC tubes showed that added 14 C-aldrin leached fastest in the soil poor in organic matter. 14 C-carbaryl was used to evaluate the effects of addition of carbon sources on its persistence and degradation in soils rich and poor in organic matter. It was found that cellulose can influence the behaviour of carbaryl in soil low in organic matter by interfering with microorganismal population. Studies on the degradation of 14 C-parathion by soil kept moist with and without repeated applications demonstrated that microbial population was modified by the repeated treatment. The adsorption, movement and persistence of the fungicide 14 C-carbendazim was examined in Brazilian soils differing in organic matter content. Soils with highest levels of organic matter showed higher sorption coefficients and lower mobility. Carbendazim was very persistent in all soils. The metabolite 2-benzimidazolecarbamate was the main degradation product detected. Experiments with 14 C-metalaxyl showed that sorption coefficients in the Humic Gley soil were 0.8 and in the Dark Red Latosol soil 0.3. Data are in agreement with the high mobility of 14 C-metalaxyl in soil thin-layers. Also, a metabolite was detected in percentages varying from 3 to 10% specially in the Humic Gley soil samples

  8. Mass Transport within Soils

    Energy Technology Data Exchange (ETDEWEB)

    McKone, Thomas E.

    2009-03-01

    Contaminants in soil can impact human health and the environment through a complex web of interactions. Soils exist where the atmosphere, hydrosphere, geosphere, and biosphere converge. Soil is the thin outer zone of the earth's crust that supports rooted plants and is the product of climate and living organisms acting on rock. A true soil is a mixture of air, water, mineral, and organic components. The relative proportions of these components determine the value of the soil for agricultural and for other human uses. These proportions also determine, to a large extent, how a substance added to soil is transported and/or transformed within the soil (Spositio, 2004). In mass-balance models, soil compartments play a major role, functioning both as reservoirs and as the principal media for transport among air, vegetation, surface water, deeper soil, and ground water (Mackay, 2001). Quantifying the mass transport of chemicals within soil and between soil and atmosphere is important for understanding the role soil plays in controlling fate, transport, and exposure to multimedia pollutants. Soils are characteristically heterogeneous. A trench dug into soil typically reveals several horizontal layers having different colors and textures. As illustrated in Figure 1, these multiple layers are often divided into three major horizons: (1) the A horizon, which encompasses the root zone and contains a high concentration of organic matter; (2) the B horizon, which is unsaturated, lies below the roots of most plants, and contains a much lower organic carbon content; and (3) the C horizon, which is the unsaturated zone of weathered parent rock consisting of bedrock, alluvial material, glacial material, and/or soil of an earlier geological period. Below these three horizons lies the saturated zone - a zone that encompasses the area below ground surface in which all interconnected openings within the geologic media are completely filled with water. Similarly to the unsaturated

  9. Effect of leaf litter quantity and type on forest soil fauna and biological quality

    OpenAIRE

    Zhizhong Yuan; Yang Cui; Shaokui Yan

    2013-01-01

    It is important to assess forest litter management. Here we examined the effects of leaf litter addition on the soil faunal community in Huitong subtropical forest region in Hunan Province, China. The microcosm experiment involving leaf-litter manipulation using a block and nested experimental design, respectively, was established in May, 2011. In the block design, the effects of litter quantity and its control were examined, while in the nested design a comparison was made of litter quality ...

  10. Secondary successions of biota in oil-polluted peat soil upon different biological remediation methods

    Science.gov (United States)

    Melekhina, E. N.; Markarova, M. Yu.; Shchemelinina, T. N.; Anchugova, E. M.; Kanev, V. A.

    2015-06-01

    The effects of different bioremediation methods on restoration of the oil-polluted peat soil (Histosol) in the northernmost taiga subzone of European Russia was studied. The population dynamics of microorganisms belonging to different trophic groups (hydrocarbon-oxidizing, ammonifying, nitrifying, and oligonitrophilic) were analyzed together with data on the soil enzyme (catalase and dehydrogenase) activities, population densities of soil microfauna groups, their structures, and states of phytocenoses during a sevenyear-long succession. The remediation with biopreparations Roder composed of oil-oxidizing microorganisms-Roder with Rhodococcus rubber and R. erythropolis and Universal with Rhodotorula glutinis and Rhodococcus sp.-was more efficient than the agrochemical and technical remediation. It was concluded that the biopreparations activate microbiological oil destruction, thereby accelerating restoration succession of phytocenosis and zoocenosis. The succession of dominant microfauna groups was observed: the dipteran larvae and Mesostigmata mites predominant at the early stages were replaced by collembolans at later stages. The pioneer oribatid mite species were Tectocepheus velatus, Oppiella nova, Liochthonius sellnicki, Oribatula tibialis, and Eupelops sp.

  11. The influence of pine forests of different ages on the biological activity of layland soils in the middle Angara River basin

    Science.gov (United States)

    Sorokina, O. A.; Sorokin, N. D.

    2007-05-01

    The influence of pine forests of different ages (from 25 to 85 years) restoring on old plow land soils is reflected in the biological processes proceeding in them. The drastic decrease in the absolute and relative number of actinomycetes, along with an increase of the fungal population in the microbial complexes of the soils (within the whole profiles), indicates that the microbocenoses acquire “forest” properties. In the soils under the younger pine forests, the processes of microbiological mineralization and specific respiration activity are more active than in the soils under the older pine forests. With the age of the pine forests, the soil profiles become more differentiated according to the eluvial-illuvial type.

  12. Alpha spectroscopic determination of plutonium and uranium in food, biological materials, and soils

    International Nuclear Information System (INIS)

    Frindik, O.

    1980-07-01

    An alpha-spectrometric method for the plutonium determination which was tested in different samples is described in detail. In particular, this method is capable of determining the very low plutonium levels found in food at present, and allow recoveries of 85-95% of the tracer added. Inorganic samples, such as soil samples for example, can be analyzed by using an abbreviated modification of the method. The measuring preparations show a high degree of spectral purity. Uranium can be separated during the analytical procedure and, after purification, can also be determined alpha-spectrometrically. 90-100% of the uranium are recovered. (orig.) [de

  13. Impact of long term applications of cotton pesticides on soil biological properties, dissipation of [14C]-methyl parathion and persistence of multi-pesticide residues

    International Nuclear Information System (INIS)

    Andrea, M.M.; Peres, T.B.; Luchini, L.C.; Marcondes, M.A.; Pettinelli, A. Jr.; Nakagawa, L.E.

    2001-01-01

    Biological parameters were followed in soils from a cotton farm (Tatui) where the recommended pesticides have been used for years, and from an experimental field (Sao Paulo) which was subdivided in two areas: one received the recommended pesticides and the other was maintained untreated. The soil bioactivities monitored from 1995 to 1998, after different pesticide applications, were: basal and glucose-induced respiration; anaerobic activity; nitrification rate; activity of the enzymes: dehydrogenase, aryl sulfatase and arginine deaminase; the soil capacity to mineralize an aromatic pesticide molecule ([ 14 C]-2,4-D), fungal and bacterial contributions for soil respiration until the beginning of 1998, and fungal and bacterial numbers from the beginning of 1998. The dissipation of [ 14 C]-methyl parathion - one of the recommended pesticides - was followed by radiometric techniques only in Sao Paulo, but persistence of multi-residues was determined in both soils by gas-liquid chromatography. All the biological parameters varied each sampling time and values also varied among soil samples, being inhibited or stimulated by the different pesticide applications, but they mostly recovered the initially detected activity. Dissipation of methyl parathion was fast and not affected by the other pesticide applications. Pesticide residues varied between the two soils but were mostly low after all applications, which indicates their dissipation. (author)

  14. Combined use of GIS and environmental indicators for assessment of chemical, physical and biological soil degradation in a Spanish Mediterranean region.

    Science.gov (United States)

    de Paz, José-Miguel; Sánchez, Juan; Visconti, Fernando

    2006-04-01

    Soil is one of the main non-renewable natural resources in the world. In the Valencian Community (Mediterranean coast of Spain), it is especially important because agriculture and forest biomass exploitation are two of the main economic activities in the region. More than 44% of the total area is under agriculture and 52% is forested. The frequently arid or semi-arid climate with rainfall concentrated in few events, usually in the autumn and spring, scarcity of vegetation cover, and eroded and shallow soils in several areas lead to soil degradation processes. These processes, mainly water erosion and salinization, can be intense in many locations within the Valencian Community. Evaluation of soil degradation on a regional scale is important because degradation is incompatible with sustainable development. Policy makers involved in land use planning require tools to evaluate soil degradation so they can go on to develop measures aimed at protecting and conserving soils. In this study, a methodology to evaluate physical, chemical and biological soil degradation in a GIS-based approach was developed for the Valencian Community on a 1/200,000 scale. The information used in this study was obtained from two different sources: (i) a soil survey with more than 850 soil profiles sampled within the Valencian Community, and (ii) the environmental information implemented in the Geo-scientific map of the Valencian Community digitised on an Arc/Info GIS. Maps of physical, chemical and biological soil degradation in the Valencian Community on a 1/200,000 scale were obtained using the methodology devised. These maps can be used to make a cost-effective evaluation of soil degradation on a regional scale. Around 29% of the area corresponding to the Valencian Community is affected by high to very high physical soil degradation, 36% by high to very high biological degradation, and 6% by high to very high chemical degradation. It is, therefore, necessary to draw up legislation and to

  15. Biological effects of decabromodiphenyl ether (BDE209) and Pb on earthworm (Eisenia fetida) in a soil system

    International Nuclear Information System (INIS)

    Li, Jing; Zhang, Wei; Chen, Lin; Liang, Jun; Lin, Kuangfei

    2015-01-01

    BDE209 and Pb are ubiquitous contaminants at e-waste recycling sites (EWRSs). This study aimed to determine acute and sub-acute toxicity to earthworm Eisenia fetida induced by BDE209 and Pb in natural soil. Results demonstrated that the inhibition of Pb on growth and reproduction of earthworms followed a dose-dependent pattern. Earthworms exposed to 100 mg kg −1 of BDE209 displayed avoidance responses, while the soil indicated a more obvious decline of habitat function with the increase of Pb level. Comet assay suggested that increasing concentrations of Pb exposure resulted in a gradual increase in the tail length and olive tail moment, which meant that the degree of DNA damage was promoted. BDE209 addition could reduce the damage; therefore the joint effects of both chemicals showed antagonistic. These results revealed that joint exposure (BDE209-Pb) could elicit pronounced biochemical and physiological responses in earthworms, and the DNA damage might be potential molecular biomarker of the two pollutants. - Highlights: • 48 h and 14 d LC 50 values of BDE209 were lower than that of Pb, suggesting Pb was more toxic to earthworms. • Inhibition of Pb on the growth and reproduction of earthworms followed certain dose–response relationships. • Joint effects of BDE209 and Pb on earthworms might be antagonistic in comet assay. - This study demonstrated the biological effects of BDE209-Pb joint exposure on earthworm Eisenia fetida in a soil system for the first time.

  16. Transdomes sampling of lower and middle crust

    Science.gov (United States)

    Teyssier, C. P.; Whitney, D. L.; Roger, F.; Rey, P. F.

    2015-12-01

    Migmatite transdomes are formed by lateral and upward flow of partially molten crust in transtension zones (pull-apart structures). In order to understand the flow leading to this type of domes, 3D numerical models were set-up to simulate the general case of an extensional domain located between two strike-slip faults (pull-apart or dilational bridge). Results show that upper crust extension induces flow of the deep, low-viscosity crust, with rapid upward movement of transdome material when extension becomes localized. At this point a rolling hinge detachment allows rapid removal of upper crust. The internal structure of transdomes includes a subvertical high strain zone located beneath the zone of localized upper crust extension; this shear zone separates two elongate subdomes of foliation that show refolded/sheath folds. Lineation tends to be oriented dominantly subhorizontal when the amount of strike-slip motion is greater than the amount of upward flow of dome rocks. Models also predict nearly isothermal decompression of transdome material and rapid transfer of ~50 km deep rocks to the near surface. These model results are compared to the structural and metamorphic history of several transdomes, and in particular the Variscan Montagne Noire dome (French Massif Central) that consists of two domes separated by a complex high strain zone. The Montagne Noire dome contains ~315 Ma eclogite bodies (U-Pb zircon age) that record 1.4 GPa peak pressure. The eclogite bodies are wrapped in highly sheared migmatite that yield 314-310 Ma monazite ages interpreted as the metamorphism and deformation age. Based on these relations we conclude that the Montagne Noire transdome developed a channel of partially molten crust that likely entrained eclogite bodies from the deep crust (~50 km) before ascending to the near-surface. One implication of this work is that the flowing crust was deeply seated in the orogen although it remained a poor recorder of peak pressure of metamorphism

  17. Biological N2 fixation by chickpea in inter cropping system on sand soil

    International Nuclear Information System (INIS)

    Ismail, M. M.; Moursy, A. A. A.; Kotb, E. A.; Farid, I. M.

    2012-12-01

    A field experiment was carried out at the plant nutrition and fertilization unit, Soils and Water Research Department, Nuclear Research Center, Atomic Energy Authority, Inshas, Egypt on wheat and chickpea incorporating. The benefits of N 2 fixation by legumes to cereals growing in inter crops or to grasses growing in mixed swards are high clear. In cases the benefit to the N status of cereals has bee seen when they are inter cropped with legumes, where benefit is found, it is mainly due to sparing of soil N rather than direct transfer from the legume. Inter cropped wheat, has a high grains yield as compared to those recorded under sole crop. The application of inter cropping system an increase of wheat grain yield against the sole system, regardless the cultivation system, the over all means of fertilizer rates indicated (50% MF + 50% OM) treatment was superiority (100% OM) and (75% MF + 25% OM) or those recorded with either un fertilizer when wheat grain yield considered. Comparison heed between or gain sources reflected the superiority of compost under sole cultivation, while chickpea straw was the best under inter cropping. Inter cropped has a high grain N uptake compared to soil systems. While totally organic materials had accumulates more N in grains than those of untreated treated control. In the some time, the overall mean indicated the superiority of compost treatment combined with 50% mineral fertilizer under inter cropping system over those of either only organic materials treatment or those combined with 75% mineral fertilizer. Plants treated of chickpea straw and compost, achieved the best value of straw weight. A mong the organic manure treatments, chickpea straw and compost seem to be the best ones. Nitrogen derived from air (%Ndfa) shoots and seeds of chickpea plants: In case of cow manure and maize stalk, the best value of nitrogen derived from air was detected followed by compost, while the lowest value was recorded with wheat straw. In general

  18. Biological N2 Fixation by Chickpea in inter cropping System on Sand Soil

    International Nuclear Information System (INIS)

    Ismail, M. M.; Moursy, A. A. A.; Kotb, E. A.; Farid, I. M.

    2012-12-01

    A field experiment was carried out at the plant Nutrition and Fertilization Unit, Soils and Water Research Department, Nuclear Research Center, Atomic Energy Authority, Inshas, Egypt on wheat and chickpea inter cropping. The benefits of N 2 fixation by legumes to cereals growing in inter crops or to grasses growing in mixed swards are high clear. in cases the benefit to the N status of cereals has bee seen when they are inter cropped with legumes , where benefit is found ,it is mainly due to sparing of soil N rather than direct transfer from the legume. inter cropped wheat has a high grains yield as compared to those recorded under sole crop. The application of inter cropping system induced an increase of wheat grain yield against the sole system. regardless the cultivation system, the over all means of fertilizer rates indicated (50% MF + 50% OM) treatment was superiority (100% OM) and (75% MF + 25% OM) or those recorded with either un fertilizer when wheat grain yield considered. Comparison heed between organic sources reflected the superiority of under sole cultivation, while chickpea straw was the best under inter cropping. Inter cropped has a high grain N uptake compared to soil system. While totally organic materials had accumulates more N in grain than those of underrated treated control. In the same time, the overall mean indicated the superiority of compost treatment combined with 50% mineral fertilizer under inter cropping system over those of either only organic materials treatment or those combined with 75% mineral fertilizer. Plants treated of chickpea straw and compost, achieved the best value of straw weight. Among the organic manure treatments, chickpea straw and compost seem to be the best ones. Nitrogen derived from air (% Ndfa) shoots and seeds of chickpea plant: In case of cow manure and maize stalk, the best value of nitrogen derived from air was detected followed by compost, while the lowest value was recorded with wheat straw. In general

  19. Recycling of biological sludge for the fertilizing of soils cultivated with Lolium perenne

    Directory of Open Access Journals (Sweden)

    Florica Morariu

    2017-05-01

    Full Text Available The present study has been elaborated with the aim of justifying the high efficiency of in-situ slaughterhouse sludge recycling and its usage in Lolium perenne cultures. Stabilized slaughterhouse sludge was used to complete the high deficiency in nutrients of the poor terrains. Slaughterhouse sludge represents an excessive, final by product from a meat-processing unit in Western Romania. It contains 59.78-90.77% easily bio-degradable organic substances. Moreover, it has compounds containing nitrogen and phosphorus, total N=1.922-3.318%, total P=1107-1126mg•kg-1D.M. The experimental variants have been prepared, having the following characteristics: control variants of non-fertilized soils and variants of soils fertilized with slaughterhouse sludge, 50t•ha-1. The experimental variants used were arranged in a completely randomized block design, with three replicates each. The efficiency of fertilization with slaughterhouse sludge was a 30-35% rise in the quantity of grass harvested vs. the quantities harvested from the control variants. The quantity of Cd and Pb has been determined from the aerial parts of the harvested plants and they were below the maximum limit admitted by the sanitary regulations in Romania. Cr didn’t bio-accumulate in plants at a detection limit. The quantity of other metals determined from the aerial parts of the plants was low: i.e. <10mg•kg-1D.M. for Cu or Ni <50mg•kg-1D.M. for Zn, <150mg•kg-1D.M.for Mn. Green feed harvested from fields fertilized with slaughterhouse sludge can be part of animal nutrition.

  20. Humic substances, their microbial interactions and effects on biological transformations of organic pollutants in water and soil: A review.

    Science.gov (United States)

    Lipczynska-Kochany, Ewa

    2018-07-01

    Depicted as large polymers by the traditional model, humic substances (HS) tend to be considered resistant to biodegradation. However, HS should be regarded as supramolecular associations of rather small molecules. There is evidence that they can be degraded not only by aerobic but also by anaerobic bacteria. HS presence alters biological transformations of organic pollutants in water and soil. HS, including humin, have a great potential for an application in aerobic and anaerobic wastewater treatment as well as in bioremediation. Black carbon materials, including char (biochar) and activated carbon (AC), long recognized effective sorbents, have been recently discovered to act as effective redox mediators (RM), which may significantly accelerate degradation of organic pollutants in a way similar to HS. Humic-like coating on the biochar