Klára Komprdová

Influence of climate and land use change on spatially resolved volatilization of persistent organic pollutants (POPs) from background soils.

The subject of this study is the assessment of the influence of climate and land use change on the potential re-emission of organochlorine pesticides (OCPs) from background and agricultural soils. A deterministic spatially and temporally explicit model of the air-surface exchange was created, fed with distributed data of soil and atmospheric concentrations from real measurements, and run under various scenarios of temperature and land use change for a case study area representative of central European conditions. To describe land use influence, some important features were implemented including effect of plowing, influence of land cover, temperature of soil, and seasonal changes of air layer stability. Results show that volatilization of pesticides from soil largely exceeded dry gas deposition in most of the area. Agricultural soils accounted for more than 90% of the total re-emissions both because of the generally higher soil fugacities (higher loads of chemicals and relatively low organic carbon content), but also due to physical characteristics and land management practices enhancing the dynamics of the exchange. An increase of 1 °C in air temperature produced an increase of 8% in the averaged total volatilization flux, however this effect can be neutralized by a change of land use of 10% of the arable lands to grassland or forest, which is consistent with projected land use change in Europe. This suggests that future assessment of climate impact on POP fate and distribution should take into consideration land use aspects.

Development and comparison of regression models for the uptake of metals into various field crops

Field crops represent one of the highest contributions to dietary metal exposure. The aim of this study was to develop specific regression models for the uptake of metals into various field crops and to compare the usability of other available models. We analysed samples of potato, hop, maize, barley, wheat, rape seed, and grass from 66 agricultural sites. The influence of measured soil concentrations and soil factors (pH, organic carbon, content of silt and clay) on the plant concentrations of Cd, Cr, Cu, Mo, Ni, Pb and Zn was evaluated. Bioconcentration factors (BCF) and plant-specific metal models (PSMM) developed from multivariate regressions were calculated. The explained variability of the models was from 19 to 64% and correlations between measured and predicted concentrations were between 0.43 and 0.90. The developed hop and rapeseed models are new in this field. Available models from literature showed inaccurate results, except for Cd; the modelling efficiency was mostly around zero. The use of interaction terms between parameters can significantly improve plant-specific models.

Accumulation kinetics and equilibrium partitioning coefficients for semivolatile organic pollutants in forest litter.

Soils are important stores of environmentally cycling semivolatile organic contaminants (SVOCs) and represent relevant atmospheric secondary sources whenever environmental conditions favor re-emission. The exchange between air and soil is controlled by resistances posed by interfacial matrices such as the ubiquitously distributed vegetation litter. For the first time, this study focused on the experimental characterization of accumulation parameters for SVOCs in litter under real field conditions. The logarithm of the litter-air equilibrium partitioning coefficient ranged 6.8-8.9 and had a similar dependence on logKOA as that of plant foliage and soil data. Uptake and release rates were also KOA dependent with values (relevant for real environmental conditions) ranging 30,000-150,000 d(-1) and 0.0004-0.0134 d(-1), respectively. The overall mass transfer coefficient v controlling litter-air exchange (0.03-1.4 cm s(-1)) was consistent with previously reported data of v for foliage in forest canopies after normalization on leaf area index. Obtained data suggest that litter holds the potential for influencing atmospheric fugacity in proximity to soil, likely affecting overall exchange of SVOCs between the soil reservoir and the atmosphere.

The influence of tree species composition on the storage and mobility of semivolatile organic compounds in forest soils.

Soil contamination with PCBs and PAHs in adjacent forest plots, characterized by a distinct composition in tree species (spruce only, mixed and beech only), was analyzed to investigate the influence of ecosystem type on contaminant mobility in soil under very similar climate and exposure conditions. Physical-chemical properties and contaminant concentrations in litter (L), organic (F, H) and mineral (A, B) soil horizons were analyzed. Contaminant distribution in the soil core varied both in relation to forest type and contaminant group/properties. Contaminant mobility in soil was assessed by examining the ratios of total organic carbon (TOC)-standardized concentrations across soil horizons (Enrichment factors, EFTOC) and the relationship between EFTOC and the octanol-water equilibrium partitioning coefficient (KOW). Contaminant distribution appeared to be highly unsteady, with pedogenic/biogeochemical drivers controlling contaminant mobility in organic layers and leaching controlling accumulation in mineral layers. Lighter PCBs displayed higher mobility in all forest types primarily controlled by leaching and, to a minor extent, diffusion. Pedogenic processes controlling the formation of soil horizons were found to be crucial drivers of PAHs and heavier PCBs distribution. All contaminants appeared to be more mobile in the soil of the broadleaved plot, followed by mixed canopy and spruce forest. Increasing proportion of deciduous broadleaf species in the forest can thus lead to faster degradation or the faster leaching of PAHs and PCBs. The composition of humic substances was found to be a better descriptor of contaminant concentration than TOC.

Impact of Floods and Their Frequency on Content and Distribution of Risk Elements in Alluvial Soils

The aim of this study was to compare the pollution levels of risk elements in flooded and non-flooded alluvial soils as a function of inundation frequency and river distance, depth of soil horizon, and pollution origin. Totally, 43 soil profiles of flooded and non-flooded soils were sampled in two layers (topsoil and subsoil). The total contents of As, Cd, Co, Cr, Cu, Mo, Ni, Pb, V, and Zn were measured and grouped according to the assumed geogenic or anthropogenic origin. Flooded soils were classified according to inundation stage/river distance. Concerning the depth gradient, it can be concluded that the content of anthropogenic risk elements decreased with the depth, while geogenic risk elements revealed no trend. The distance from the river had no influence on the distribution of anthropogenic risk elements in soil. On the contrary, geogenic risk elements showed increasing concentrations with increasing distance. These results indicate that frequency of floods has no influence on the risk elements distribution in soil. The process of sedimentation seems to be the main factor influencing the level of pollution, it differs between groups of anthropogenic and geogenic risk elements. The result of this countrywide study shows higher levels of soil contamination in flooded areas even without significant point sources of pollution, than in non-flooded areas in standard agricultural conditions.

The variability of standard artificial soils: effects on the survival and reproduction of springtail (Folsomia candida) and potworm (Enchytraeus crypticus).

Recent studies have documented significant variability in the basic properties of artificial soil which is used as a standard medium in soil bioassays. Variability in key soil properties could confound the interpretation of toxicity data and bias the output of bioassays. The main aims of this study were (i) to identify the variability in the endpoints survival and reproduction of Folsomia candida and Enchytraeus crypticus related to the artificials soils prepared in different laboratories and (ii) to identify the specific physico-chemical properties of the artificial soils which influence the bioassays results. The results of reproduction tests showed that nearly all tested artificial soils were suitable for the survival and reproduction of both organisms as the validity criteria from the test standards were fulfilled. However, numbers of juveniles varied significantly among soils. The most important factor for F. candida performance was a coarser soil structure. C:N ratio (<22.6) were important for the reproduction of E. crypticus. Both species tolerated a pH (KCl) of artificial soils in the range of 4.27-6.8 and even low TOC (1.5%). Thus, it is possible to reduce peat content in artificial soils, which may increase the comparability of results to those for natural soils.

Comparison of approaches towards ecotoxicity evaluation for the application of dredged sediment on soil

PurposeThe toxicity of 36 dredged sediments from the Czech Republic was investigated using a large battery of bioassays. The aim of this study was to investigate the feasibility of ecotoxicity testing in general and of individual bioassays more specific and to investigate how the results of bioassays are determined by the physicochemical properties of sediment samples and/or sediment contamination.Material and methodsIn 2008 and 2010, 36 sediment samples were collected from rivers and ponds and from sediment heaps in different parts of the Czech Republic. Both their physicochemical properties and their levels of contamination with POPs and heavy metals were analyzed. The ecotoxicities of the sediments were evaluated using the four bioassays from the new Czech directive 257/2009 Coll. concerning the application of dredged sediments on agricultural land (Enchytraeus crypticus reproduction, Folsomia candida reproduction, Lactuca sativa root elongation, and potential ammonium oxidation). The results of the four directive bioassays were compared with the results of other soil bioassays (Caenorhabditis elegans mortality, Eisenia fetida avoidance and reproduction) and eluate bioassays (Daphnia magna immobilization, Pseudokirchneriella subcapitata growth inhibition test, and Vibrio fischeri luminescence).Results and discussionWe demonstrate that the battery suggested in Czech directive 257/2009 Coll. is highly effective in identifying toxic samples; these bioassays clearly revealing different types of toxicity and different exposure routes. Shorter alternative bioassays may be added especially when fast toxicity identification is needed. Eluate bioassays identified samples potentially hazardous to aquatic ecosystems. Their inclusion into the assessment scheme should be considered if the goal of assessment is also the protection of aquatic ecosystems. The results of our multivariate analysis show that specific physicochemical properties and contamination may affect bioassay responses. C. elegans was the most sensitive bioassay to physicochemical properties and also to organic contamination, while eluate bioassays were sensitive to heavy metal pollution.ConclusionsMost effects detected by the bioassays could not be explained by the levels of toxicants measured or by the natural characteristics of sediments. Our results show that bioassays are irreplaceable in dredged sediment risk assessment because they complement information provided by chemical analyses.

GENASIS Information System: A Global Environmental Assessment of Persistent Organic Pollutants

Global ENvironmental ASsessment and Information System (GENASIS) is a tool developed by expert teams of the Research Centre for Toxic Compounds in the Environment (RECETOX) and the Institute for Biostatistics and Analyses (IBA) of the Masaryk University in Brno. The aim of GENASIS is to compile validated data on persistent organic pollutants, including their properties, sources, long-term levels, life times, transport mechanisms, effects and risks, scattered throughout various institutions and ministries, and to provide tools for their visualization, analyses, interpretation, assessment of environmental and human risks or modelling of fate. Such a tool should significantly enhance comprehensive understanding of the fate of POPs in the environment, their impacts on ecosystem and the human population.

Spatial Soil Modeling of Organochlorine Pesticides, Their Pools and Volatilization Fluxes

The goal of this study was to use the modeling tools for prediction of environmental concentrations and pools of pesticides (HCB and DDT) in soil. The characterization and quantification of secondary background sources of HCB, were computed using fugacity based deterministic model. Areas with a high potential for deposition and volatilization of HCB were identified. Results of modeling were maps showing spatial distribution of HCB and DDT in the Czech Republic which have been visualized on the web portal GENASIS (Global Environmental Assessment Information System) to provide information on environment contamination.