Milan Sáňka

Soil burdens of persistent organic pollutants - their levels, fate and risk. Part I. Variation of concentration ranges according to different soil uses and locations.

Detailed soil screening data from the Czech Republic as a typical Central European country are presented here. Determination of a wide selection of organic and inorganic pollutants as well as an assessment of specific soil parameters allowed us to study the soil contamination in relation to the land use and soil properties. While HCHs and HCB were found at highest levels in arable soils, the higher concentrations of PCDDs/Fs, PCBs, PAHs and DDTs were observed in high altitude forest soils. Concentrations of these compounds strongly correlated with the soil organic carbon content. Several possible reasons have been suggested for the observed higher concentrations in mountain forest soils but the impact of each of these influencing factors remains to be identified. An inventory of the soil contamination is needed as a first step in our effort to estimate an extent to which the secondary sources contribute to the enhanced atmospheric levels of POPs.

Soil burdens of persistent organic pollutants--their levels, fate and risks Part III. Quantification of the soil burdens and related health risks in the Czech Republic.

A total number of 471 soil samples collected during the period of 1996-2006 from the agricultural and forest areas of the Czech Republic were analyzed for their content of persistent organic pollutants (POPs). Spatial variability of the POP concentrations was assessed using an IDW spatial GIS model analysis. For every grid of the network, resulting modeled levels of contamination allowed for estimation of the total burden of POPs in soils. Potential risks associated with contaminated soils were assessed as well. Database of the old ecological burdens counting 3061 sampling sites was used to adjust the model and incorporate the risks of heavily contaminated sites. The high levels of health risks were only found at less than 1% of the area of interest. The IDW modeling proved to be a useful tool for screening of the health risks in the large areas with scarce monitoring data. Presented approach can be applied in the risk management, to support an efficient targeting of the risk reduction measures, or to improve a design of the national monitoring.

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.

Soil burdens of persistent organic pollutants - Their levels, fate and risk : Part II. Are there any trends in PCDD/F levels in mountain soils?

Good quality data apt for an assessment of temporal trends of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs) in soils are difficult to obtain since there is a general lack of information on their residues in soils. Variability of soil profiles, non-homogeneity of samples, and often also inconsistency of applied sampling procedures further complicate this problem. To assess spatial and temporal trends of contamination, three soil sampling campaigns have been performed over the period of 12 years at the mountain forest sites in the Czech Republic. Relation between the air, needle and soil contaminations was addressed in addition to time-related variability of soil. It has been confirmed that soil is a good matrix for evaluation of spatial distribution of persistent organic pollutants (POPs) but difficult for establishment of temporal trends. A slow rate of the soil-forming processes and their site-specificity was generally the major source of uncertainties.

COMPARISON OF SEVERAL SOIL EXTRACTANTS FOR DETERMINATION OF THALLIUM

Thallium (Tl) and its compounds are toxic to all organisms. Relatively high levels of thallium of pedogeochemical origin have been found in some areas of the Czech Republic. The contents of >2 mg kg−1 of Tl have been found in aqua regia soil extracts of soils originated from melanocratic porphyric hornblende-biotite granite or from hornblende-biotite granodiorite. The contents of Tl in the range of 0.45–1 mg kg−1 have occurred mainly in soils originated from paragneiss. A detailed study of some of these sites has been made. Content of thallium in soils was determined after extraction with aqua regia, 2 M HNO3, DTPA-TEA and 1 M NH4NO3. Plant samples (whole rapeseed kernels) were wet ashed and the total content of Tl was determined. The amount of Tl in soils extracted by the different extracting methods in comparison to aqua regia (100%) was approximately 14% for 2 M HNO3, 0.8% for 1 M NH4NO3 and only about 0.03% for DTPA-TEA. The content of Tl in the rapeseeds was approximately 75% of this element determined in soils after extraction by aqua regia. The relationships among the extractants were found to be relatively close except for 1 M NH4NO3. It was found that the transfer of Tl into rapeseeds depends on the status of this element in the particular soil and that the soil substrate is the main factor influencing this status.

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.

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.

Soil Contamination Health Risks in Czech Proposal of Soil Protection Legislation

A new system of soil contamination limit values proposed for Czech legislation is described. The system is based on the hierarchical limit values system with two levels. The first one—prevention limit—defined background values of risk lements (REs) and persistent organic pollutants (POPs) in Czech agricultural soils supported by the data from soil monitoring system. The second one—indication limit—is defined for human health protection by two principles, the protection of food chain and the protection of direct human health risks by inhalation, dermal and oral intake of RE and POPs in soil particles on the field. The practical application of limit values proposal was applied in the roject focused on soil contamination influence on health and environmental risks in fluvial zones of Czech important river basins. The floodplain soils belong to the most contaminated soils in Europe generally and the project defined the potential fluvial areas with increased human health risks.

The role of Mn and Fe oxides in risk elements retention in soils under different forest types

Retention of four selected risk elements (SRE)-arsen (As), cadmium (Cd), lead (Pb), zinc (Zn)-by manganese (Mn) and iron (Fe) oxides in different forest soils was investigated. The abundance of oxides and the association between oxides and SRE were observed in 91 soil samples of different forests divided into 5 categories covering the variability of forests in the Czech Republic. The sequential extraction procedure was used for dissolution of Mn and Fe oxide fractions (MnOF and FeOF) separately and together with the associated elements. It was found that Mn associated with MnOF is significantly higher in deciduous forests. These differences were ascribed mainly to the higher pH and lower DOC (dissolved organic carbon) in deciduous forests. The association of SRE with MnOF declines in the order Cd >> Pb > Zn > As and the association with FeOF in the order As approximate to Pb >> Cd > Zn. Despite their relatively lesser occurrence, MnOFs were found to be very significant for retention of Cd. FeOF is strongly associated with As and Pb. The category of forest has been identified to influence the amount of SRE retained by oxides especially in two cases: (1) the category of forests on Fluvisols differs from the other categories; (2) the retention of Cd by MnOF or FeOF is larger in deciduous forests compared with coniferous forests.

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.