Edgar Hiller

Impact of wheat straw biochar addition to soil on the sorption, leaching, dissipation of the herbicide (4-chloro-2-methylphenoxy)acetic acid and the growth of sunflower (Helianthus annuus L.)

Biochar addition to agricultural soils might increase the sorption of herbicides, and therefore, affect other sorption-related processes such as leaching, dissipation and toxicity for plants. In this study, the impact of wheat straw biochar on the sorption, leaching and dissipation in a soil, and toxicity for sunflower of (4-chloro-2-methylphenoxy)acetic acid (MCPA), a commonly used ionizable herbicide, was investigated. The results showed that MCPA sorption by biochar and biochar-amended soil (1.0wt% biochar) was 82 and 2.53 times higher than that by the non-amended soil, respectively. However, desorption of MCPA from biochar-amended soil was only 1.17 times lower than its desorption in non-amended soil. Biochar addition to soil reduced both MCPA leaching and dissipation. About 35% of the applied MCPA was transported through biochar-amended soil, while up to 56% was recovered in the leachates transported through non-amended soil. The half-life value of MCPA increased from 5.2d in non-amended soil to 21.5 d in biochar-amended soil. Pot experiments with sunflower (Helianthus annuus L.) grown in MCPA-free, but biochar-amended soil showed no positive effect of biochar on the growth of sunflower in comparison to the non-amended soil. However, biochar itself significantly reduced the content of photosynthetic pigments (chlorophyll a, b) in sunflower. There was no significant difference in the phytotoxic effects of MCPA on sunflowers between the biochar-amended soil and the non-amended soil. Furthermore, MCPA had no effect on the photosynthetic pigment contents in sunflower.

Fungal volatilization of trivalent and pentavalent arsenic under laboratory conditions.

Production of volatile derivatives of arsenic was studied using pure cultures of different fungal strains under laboratory conditions. Arsenic was used in its trivalent and pentavalent forms to evaluate the effect of arsenic valency on its biovolatilization. The average amount of volatilized arsenic for all fungal strains ranged from 0.026 mg to 0.257 mg and 0.024 mg to 0.191 mg of trivalent and pentavalent arsenic, respectively. These results show that approximately 23% of arsenic was volatilized from all culture media originally enriched with approximately 4 and 17 mg L(-1) of arsenic in trivalent form. The average amount of biovolatilized arsenic from culture media originally enriched with 4 and 17 mg L(-1) of arsenic in pentavalent form was 24% and 16%, respectively. The order of ability of arsenic biovolatilization is Neosartorya fischeri > Aspergillus clavatus > Aspergillus niger. Toxicity and fungal resistance to trivalent and pentavalent arsenic were also evaluated based on radial growth and biomass weight.

Sorption, desorption, and degradation of (4-chloro-2-methylphenoxy)acetic acid in representative soils of the Danubian Lowland, Slovakia.

Herbicide leaching through soil into groundwater greatly depends upon sorption-desorption and degradation phenomena. Batch adsorption, desorption and degradation experiments were performed with acidic herbicide MCPA and three soil types collected from their respective soil horizons. MCPA was found to be weakly sorbed by the soils with Freundlich coefficient values ranging from 0.37 to 1.03 mg(1-1/)(n) kg(-1) L(1/)(n). It was shown that MCPA sorption positively correlated with soil organic carbon content, humic and fulvic acid carbon contents, and negatively with soil pH. The importance of soil organic matter in MCPA sorption by soils was also confirmed by performing sorption experiments after soil organic matter removal. MCPA sorption in these treated soils decreased by 37-100% compared to the original soils. A relatively large part of the sorbed MCPA was released from soils into aqueous solution after four successive desorption steps, although some hysteresis occurred during desorption of MCPA from all soils. Both sorption and desorption were depth-dependent, the A soil horizons exhibited higher retention capacity of the herbicide than B or C soil horizons. Generally, MCPA sorption decreased in the presence of phosphate and low molecular weight organic acids. Degradation of MCPA was faster in the A soil horizons than the corresponding B or C soil horizons with half-life values ranging from 4.9 to 9.6 d in topsoils and from 11.6 to 23.4 d in subsoils.

Effect of soil and sediment composition on acetochlor sorption and desorption

Background, aim, and scopeHerbicide fate and its transport in soils and sediments greatly depend upon sorption–desorption processes. Quantitative determination of herbicide sorption–desorption is therefore essential for both the understanding of transport and the sorption equilibrium in the soil/sediment–water system; and it is also an important parameter for predicting herbicide fate using mathematical simulation models. The total soil/sediment organic carbon content and its qualitative characteristics are the most important factors affecting sorption–desorption of herbicides in soil or sediment. Since the acetochlor is one of the most frequently used herbicides in Slovakia to control annual grasses and certain annual broad-leaved weeds in maize and potatoes, and posses various negative health effects on human beings, our aim in this study was to investigate acetochlor sorption and desorption in various soil/sediment samples from Slovakia. The main soil/sediment characteristics governing acetochlor sorption–desorption were also identified.Materials and methodsThe sorption–desorption of acetochlor, using the batch equilibration method, was studied on eight surface soils, one subsurface soil and five sediments collected from the Laborec River and three water reservoirs. Soils and sediments were characterized by commonly used methods for their total organic carbon content, distribution of humus components, pH, grain-size distribution, and smectite content, and for calcium carbonate content. The effect of soil/sediment characteristics on acetochlor sorption–desorption was examined by simple correlation analysis.ResultsSorption of acetochlor was expressed as the distribution coefficient (Kd). Kd values slightly decreased as the initial acetochlor concentration increased. These values indicated that acetochlor was moderately sorbed by soils and sediments. Highly significant correlations between the Kd values and the organic carbon content were observed at both initial concentrations. However, sorption of acetochlor was most closely correlated to the humic acid carbon, and less to the fulvic acid carbon. The total organic carbon content was found to also significantly influence acetochlor desorption.DiscussionSince the strong linear relationship between the Kd values of acetochlor and the organic carbon content was already released, the corresponding Koc values were calculated. Considerable variation in the Koc values suggested that other soil/sediment parameters besides the total soil organic carbon content could be involved in acetochlor sorption. This was revealed by a significant correlation between the Koc values and the ratio of humic acid carbon to fulvic acid carbon (CHA/CFA).ConclusionsWhen comparing acetochlor sorption in a range of soils and sediments, different Kd values which are strongly correlated to the total organic carbon content were found. Concerning the humus fractions, the humic acid carbon content was strongly correlated to the Kd values, and it is therefore a better predictor of the acetochlor sorption than the total organic carbon content. Variation in the Koc values was attributed to the differences in distribution of humus components between soils and sediments. Desorption of acetochlor was significantly influenced by total organic carbon content, with a greater organic carbon content reducing desorption.Recommendations and perspectivesThis study examined the sorption–desorption processes of acetochlor in soils and sediments. The obtained sorption data are important for qualitative assessment of acetochlor mobility in natural solids, but further studies must be carried out to understand its environmental fate and transport more thoroughly. Although, the total organic carbon content, the humus fractions of the organic matter and the CHA/CFA ratio were sufficient predictors of the acetochlor sorption–desorption. Further investigations of the structural and chemical characteristics of humic substances derived from different origins are necessary to more preciously explain differences in acetochlor sorption in the soils and sediments observed in this study.

Biosorption of arsenic and cadmium from aqueous solutions

The biosorption of cadmium and arsenic from aqueous solutions onto the unmodified compact biomass of microscopic filamentous fungus Aspergillus clavatus DESM. was studied in the concentration range of 0.25 – 100 mg.l-1. The experimental biosorption results for arsenic and cadmium followed well the Freundlich equilibrium sorption model.

Metals in the Surface Sediments of Selected Water Reservoirs, Slovakia

Ruzin and Velke Kozmalovce water reservoirs (Slovakia) receive potentially toxic elements through rivers draining catchment areas polluted with the former extensive mining of ore-bearing deposits. In this study, the concentrations and fractionation of metals (antimony, arsenic, cadmium, chromium, cobalt, copper, lead, mercury, molybdenum, nickel, vanadium and zinc) have been studied in the surface sediments of the two water reservoirs. Comparison of metal concentrations found in the sediments with the mean shale values revealed a significant anthropogenic enrichment mostly with antimony (22.7), copper (8.5), zinc (5.5), cadmium (4.7), mercury (4.7), arsenic (4.5) and lead (3.9), and antimony (9.8), cadmium (8.8), zinc (4.9), lead (3.3) and arsenic (3.1) in the Ruzin and Velke Kozmalovce reservoirs, respectively. The results of fractionation study showed that the major proportion of cadmium (44.9–52.6%), cobalt (35.7–58.3%) and zinc (27.8–48.7%) was found in labile fractions, i.e., water- and acid-soluble fractions, although copper and nickel exhibited also significant labile fractions. When the risk assessment code was applied to the fractionation study, cadmium and cobalt came under high and very high risk category for the environment, and therefore might cause adverse effect to aquatic life.

Influence of Wheat Ash on the MCPA Immobilization in Agricultural Soils

Burning of crop residues in the fields is a routine post-harvest practice and results in accumulation of ashes in soils. Recent studies have shown that the ashes may significantly contribute to the herbicide sorption in soils. This study was conducted to evaluate the potential role of wheat ash in immobilization of anionic herbicide MCPA in soils. The results showed that wheat ash is highly effective sorbent for herbicide MCPA. Amendment of Fluvi-Gleyic Phaeozem and Eutric Regosol with 1% wheat ash caused a 8-fold and 16-fold increase in MCPA sorption, respectively. Desorption of MCPA was also influenced by wheat ash in soils. The addition of wheat ash to both soils increased the resistant fraction to desorption up to 80%. Generally, the field burning of crop residues appears to increase the sorption of pesticides in agricultural soils and decrease their leaching.

ARSENIC AND ZINC IN IMPOUNDMENT MATERIALS AND RELATED STREAM SEDIMENTS FROM A POLLUTED AREA IN EASTERN SLOVAKIA: DISTRIBUTION, MOBILITY, AND WATER QUALITY

Arsenic and zinc in impoundment materials and related stream sediments from a polluted area in Eastern Slovakia: distribution, mobility, and water quality The impoundment located near the village of Poša in eastern Slovakia is a significant source of arsenic. Waters penetrating the impoundment become enriched in As and other potentially toxic elements. As a consequence, the Kyjov brook and the Ondava River have been extensively polluted by arsenic. Although, zinc is of minor environmental significance regarding pollution in the area, it was also monitored to compare its behaviour with that of arsenic. The mobility and solid-state distribution of As and Zn in the impoundment materials and stream sediments have been investigated using a five-step sequential extraction procedure. Moreover, to investigate the bioavailability of As and Zn, two native plant species (Typha latifolia and Phragmites australis) growing at the site were collected and analyzed. The As concentrations in representative sediment and water samples ranged from 36.28 to 3208.35 mg kg-1 and from 4.05 to 612.8 μg l-1, respectively, both being many times above the background levels. The Zn concentrations of environmental importance were found to be high only in the impoundment materials (up to 3390 mg kg-1). Although a part of As was present in a readily soluble form (6.62%), the majority of As was mainly associated with Fe/Mn oxides (37.30%) and residual phases (51%). Similarly, the most dominant fractions for zinc distribution were Fe/Mn oxides (38.5%), residual (34%) and exchangeable (18%). Combined results of the sequential extraction tests as well as chemical and mineralogical analysis indicated that As mobilisation potential from the sediments is likely controlled by Fe/Mn oxyhydroxide mineral phases. Plants growing in the impoundment had As concentrations 10 to 100 times higher than the same plants growing in a relatively non-polluted area, indicating an enhanced bioavailability of arsenic in the area with high total As contents in the impoundment materials. Arzén a zinok v materiáloch odkaliska a v riečnych sedimentoch zo znečistenej oblasti na východnom slovensku: distribúcia, mobilita a kvalita vôd Odkalisko, ktoré sa nachádza pri obci Poša (východné Slovensko), je významným zdrojom arzénu. Vody presakujúce cez materiál uložený v odkalisku sa tak obohacujú o As a ďalšie potenciálne toxické prvky. Dôsledkom je výrazné znečistenie toku Kyjov a rieky Ondava arzénom. Aj keď v tejto oblasti zinok nepredstavuje až tak veľký environmentálny problém, je zahrnutý v tejto štúdii s cieľom porovnať správanie sa týchto dvoch potenciálne toxických prvkov. Na štúdium pohyblivosti a distribúcie As a Zn v materiáloch odkaliska a v riečnych sedimentoch sa použila päťkroková sekvenčná extrakcia. Okrem toho sme skúmali bioprístupnosť As a Zn v dvoch typoch rastlín (Typha latifolia a Phragmites australis), ktoré prednostne rastú na odkalisku. Koncentrácie As v odobratých vzorkách sedimentov boli v intervale od 36,28 do 3208,35 mg kg-1 a v povrchových vodách od 4,05 do 612,8 μg l-1. Tieto koncentrácie sú oveľa vyššie ako pozaďové hodnoty pre danú oblasť. Bolo zistené, že koncentrácie Zn významné z hľadiska znečistenia sú vysoké len v odkaliskových materiáloch (až 3390 mg kg-1). Aj keď určitý podiel As v sedimentoch bol prítomný v ľhko rozpustnej forme (6,62 %), väčšina As bola viazaná na oxidy Fe a Mn (37,30 %) a reziduálne fázy (51 %). Podobné to bolo pri Zn, pričom najdôležitejšie pre jeho distribúciu boli oxidy Fe a Mn (38,5 %), reziduálne fázy (34 %) a vymeniteľné pozície (18 %). Kombinované výsledky sekvenčných extrakcií ako aj chemickej a mineralogickej analýzy ukázali, že mobilizácia As zo sedimentov úzko súvisí s prítomnými minerálmi zo skupiny oxyhydroxidov Fe a Mn. Rastliny vyskytujúce sa na odkalisku obsahovali 10- až 100-násobne vyššie koncentrácie As ako tie isté rastliny odobraté z relatívne neznečistenej oblasti. Táto skutočnosť poukazuje na zvýšenú bioprístupnosť arzénu na skúmanom odkalisku, ktoré je typické vysokými obsahmi celkového As v uložených materiáloch.

Occurrence of selected organochlorine pesticide residues in surface sediments from the Velke Kozmalovce, Ruzin, and Zemplinska Sirava water reservoirs, Slovakia

Occurrence of selected organochlorine pesticide residues in surface sediments from the Velke Kozmalovce, Ruzin, and Zemplinska Sirava water reservoirs, Slovakia Surface sediment samples from three water reservoirs of Slovakia were analyzed for selected organochlorine pesticides (OCPs). Concentrations of total dichlorodiphenyltrichloroethanes (ΣDDTs) in the sediments from Velke Kozmalovce, Ruzin, and Zemplinska Sirava ranged from 12 to 24 ng g-1, 5 to 28 ng g-1, and 1 to 20 ng g-1, respectively, with the exception of one sediment sample from Zemplinska Sirava, having anomalously high concentration of ΣDDTs (526 ng g-1). Concentrations of hexachlorobenzene (HCB) in the sediments from these water reservoirs were generally lower and ranged from 0.3 to 9 ng g-1. Other organochlorine pesticides such as mirex, lindane and heptachlor were not detected in the surface sediments. Ratios of DDT/(DDE + DDD) were lower than 1.0 in majority of the sediment samples indicating that the degradation of the parent DDT occurred significantly and DDT in the sediments from the studied water reservoirs was derived mainly from the weathered agricultural soils. Moreover, ratios of DDD/DDE indicated that the parent DDT was degraded under aerobic conditions before depositing into the sediments of these water reservoirs. Výskyt rezíduí vybraných organochlórovaných pesticídov v sedimentoch z vodných nádrží Veľké Kozmálovce, Ružín a Zemplínska Šírava, Slovensko V štúdii boli analyzované vzorky sedimentov z troch vodných nádrží Slovenska na vybrané organochlórované pesticídy (OCPs). Koncentrácie sumy DDT a jeho metabolitov DDE a DDD (ΣDDTs) v sedimentoch z vodných nádrží Veľké Kozmálovce, Ružín a Zemplínska Šírava sa nachádzali v intervale od 12 do 24 ng g-1, od 5 do 28 ng g-1 a od 1 do 20 ng g-1, s výnimkou jednej vzorky sedimentu zo Zemplínskej Šíravy, ktorá vykazovala anomálne vysokú koncentráciu ΣDDTs (526 ng g-1). Koncentrácie hexachlórbenzénu (HCB) v sedimentoch z týchto vodných nádrží boli všeobecne nižšie a pohybovali sa v intervale od 0,3 do 9 ng g-1. Iné v sedimentoch sledované organochlórované pesticídy ako mirex, lindán a heptachlór neboli zistené. Vo väčšine vzoriek sedimentov boli hodnoty pomeru DDT/(DDE + DDD) nižšie ako 1, z čoho sa dá usúdiť, že väčšia časť pôvodne prítomného DDT sa rozložila na jeho hlavné metabolity a že DDT v sedimentoch vodných nádrží pochádza najmä z erodovaných poľnohospodárskych pôd. Hodnoty pomeru DDD/DDE ukázali, že predtým ako bol DDT deponovaný do sedimentov vodných nádrží, rozkladal sa najmä za aeróbnych podmienok.

Occurrence of selected trace metals and their oral bioaccessibility in urban soils of kindergartens and parks in Bratislava (Slovak Republic) as evaluated by simple in vitro digestion procedure

A total of eighty surface soil samples were collected from public kindergartens and urban parks in the city of Bratislava, and the <150µm soil fraction was evaluated for total concentrations of five metals, Cd, Cu, Hg, Pb and Zn, their oral bioaccessibilities, non-carcinogenic and carcinogenic health risks to children, and lead isotopic composition. The mean metal concentrations in urban soils (0.29, 36.1, 0.13, 30.9 and 113mg/kg for Cd, Cu, Hg, Pb and Zn, respectively) were about two times higher compared with background soil concentrations. The order of bioaccessible metal fractions determined by Simple Bioaccessibility Extraction Test was: Pb (59.9%) > Cu (43.8%) > Cd (40.8%) > Zn (33.6%) > Hg (12.8%). Variations in the bioaccessible metal fractions were mainly related to the total metal concentrations in urban soils. A relatively wide range of lead isotopic ratios in urban soils (1.1598-1.2088 for 206Pb/207Pb isotopic ratio) indicated a combination of anthropogenic and geogenic sources of metals in the soils. Lower values of 206Pb/207Pb isotopic ratio in the city centre and similar spatial distribution of total metal concentrations, together with their increasing total concentrations in soils towards the city centre, showed that traffic and coal combustion in former times were likely the major sources of soil contamination. The non-carcinogenic and carcinogenic health risks to children due to exposure to metals in kindergarten and urban park soils were low, with hazard index and cancer risk values below the threshold values at all studied sites.