Non-polluted Soil Research Articles

Occurrence of Hydrocarbon Degrading Genes in the Soils of the Republic of Tatarstan (Russia)

Oil pollution is one of the most serious environmental problems nowadays. The ability of soils for self-restoration is important, when choosing the strategy of pollution control. This ability depends on the pull of microbes able to decompose hydrocarbons that were present in the nonpolluted soil prior to pollution. In this study, the occurrence of alkane degrading genes in the soils of the Republic of Tatarstan being one of the oil processing regions in Russia, was investigated. It was found that alkane degrading genes belonging to group I were present in 20 of the 25 soil samples, and their abundances ranged between 0.01 and 0.07%. Alkane degrading genes belonging to group II were not detected in the samples investigated, and those belonging to group III were present in all the samples, and their abundances ranged between 0.06 and 7.25%. No correlation between the alkane degrading gene copy numbers and pH and organic carbon content in soils was revealed.

Lanthanum toxicity to five different species of soil invertebrates in relation to availability in soil

This study determined the toxicity of lanthanum, one of the most commonly used rare earth elements (REEs), to five representative soil invertebrates after 3–4 weeks exposure. Toxicity was related to total, 0.01 M CaCl2-extractable and porewater concentrations in the standard LUFA 2.2 soil, and for earthworms also to body concentrations. La sorption to LUFA 2.2 soil, estimated by relating total soil concentrations to CaCl2-extractable or porewater concentrations seemed to reach saturation at >1000 mg La/kg dry soil. Isopod (Porcellio scaber) growth was the most sensitive endpoint, followed by earthworm (Eisenia andrei), enchytraeid (Enchytraeus crypticus), springtail (Folsomia candida) and oribatid mite (Oppia nitens) reproduction, with EC50s of 312 (95% confidence interval: 5.6–619), 529 (295–762), 1010 ((>377 < 3133), 1220 (1180–1250) and 1500 (1250–1750) mg La/kg dry soil, respectively. EC50s related to CaCl2-extractable concentrations ranged between 1.3 (0.046–2.6) and 15.6 (5.6–25.7) mg La/kg dry soil, while porewater-based EC50s were 3.5 (−) and 10.2 (−) mg/L for the springtails and mites, respectively. La uptake in the earthworms linearly increased with increasing exposure concentration with bioaccumulation factors ranging between 0.04 and 0.53 (average ± SE: 0.24 ± 0.032). EC50 for effects on earthworm reproduction related to internal concentrations was 184 (61–301) mg La/kg dry body weight. A risk assessment based on the available toxicity for soil invertebrates, bacteria and plants resulted in an HC5 of approx. 50 mg La/kg dry soil, suggesting that La may affect soil ecosystems at concentrations slightly above natural background levels (6.6–50 mg La/kg dry soil) in non-polluted soils.

The effect of biochar and compost from urban organic waste on plant biomass and properties of an artificially copper polluted soil

Soil contamination with copper is a global issue, in particular in soils with a history of fertilizers, fungicides or municipal waste amendment. Several remediation techniques have been investigated to reduce the environmental impact of Cu-contaminated soil, including the use of organic amendments such as composts and biochars, which can bound part of the soluble fraction of the metal. The objective of this work is to study the effect of biochar and biochar plus compost addition on copper mobility, soil microbial biomass and growth of different plant species following remediation of a soil spiked with copper (1000 mg Cu kg−1). The contaminated soil was treated with 10 wt% of biochar or biochar plus compost. Different plant species (mustard, cress and ryegrass) were grown in the soil during 4 weeks. A significant reduction on the mobile form of Cu was observed in soils treated with biochar and biochar plus compost. The highest microbial biomass values were obtained in samples treated with biochar plus compost. After cress growth, the microbial biomass of soil treated with biochar plus compost was similar to that of non-polluted soil. The germination test showed increased root length in the amended soils compared to the contaminated soils. With respect to biomass growth of vegetable species in copper polluted soil, only ryegrass presented a satisfactory growth in the contaminated soil without the biochar treatment. For mustard and cress, biomass growth was only observed following biochar addition.

Determination of As concentration in earthworm coelomic fluid extracts by total-reflection X-ray fluorescence spectrometry

Earthworms are often used as sentinel organisms to study As bioavailability in polluted soils. Arsenic in earthworms is mainly sequestrated in the coelomic fluids whose As content can therefore be used to asses As bioavalability. In this work, a method for determining As concentration in coelomic fluid extracts using total-reflection X-ray fluorescence spectrometry (TXRF) is presented. For this purpose coelomic fluid extracts from earthworms living in three polluted soils and one non-polluted (control) soil have been collected and analysed. A very simple sample preparation was implemented, consisting of a dilution of the extracts with polyvinyl alcohol (PVA) using a 1:8 ratio and dropwise deposition of the sample on the reflector. A detection limit of 0.2μg/l and quantification limit of 0.6μg/l was obtained in the diluted samples, corresponding to 2μg/l and 6μg/l in the coelomic fluid extracts, respectively. This allowed to quantify As concentration in coelomic fluids extracted from earthworms living in soils polluted with As at concentrations higher than 20mg/kg (considered as a pollution threshold for agricultural soils). The TXRF method has been validated by comparison with As concentrations in standards and by analysing the same samples by ICP-MS, after acid digestion of the sample. The low limit of detection, the proven reliability of the method and the little sample preparation make TXRF a suitable, cost-efficient and “green” technique for the analysis of As in earthworm coelomic fluid extracts for bioavailability studies.

ПЕРШІ РЕЗУЛЬТАТИ ЕКОМАГНІТНИХ ДОСЛІДЖЕНЬ СЛАБКОУРБАНІЗОВАНИХ МІСТ НА ПРИКЛАДІ ТРУСКАВЦЯ (УКРАЇНА) ТА МОНПЕЛЬЄ (ФРАНЦІЯ)

The objective of the present study is the assessment of the general trends for the pollution level of slightly impacted urban environment based on energy-efficient technology. The implementation of this approach is proposed on the examples of Truskavets (Ukraine) and Montpellier (France). The ultimate goal is to produce the preliminary data of the pollution with magnetic measurements. Regarding the anthropogenic pollution of the studied area the slight level of the urbanization must be accepted. The first source of the pollution is the road traffic and the second one is the railway and trams network. Non-urbanized landscape of Truskavets is presented by the forests. The soil types are gleysols. The urbanized soils of Truskavets and Montpellier are the urbozems. The magnetic susceptibility for the non-polluted soil in Truskavets is up to 8-10×10-8 m3/kg, very low values for Ukrainian soils, were registered. At the same time the polluted soils collected from the profiles and under the areal researches near the roadway and railway are characterized by a much higher MS: χ=36-162×10-8 m3/kg. The pollution of the soils were confirmed by the frequency dependence of magnetic susceptibility with the values of χfd= 2-3. The tree leaves from the Montpellier have much higher isothermal remanence along the roadway and tram line comparing with the natural area. The magnetic mineralogical analyses included thermomagnetic studies, hysteresis and remanence acquisition, ARM, and S ratio. The magnetite-like phase as the main magnetic mineral responsible for the magnetic enchantments in polluted soil was identified. At the same time non-polluted soil may contain the small amount of the single-domain (SD) particles and the high coercivity minerals such as haematite and goethite. Our results are valuable for the environmental management companies, centers of environmental monitoring, and geophysical observatories. Low cost, non-destructive and rapid magnetic techniques are promising in monitoring soil and air pollution both in highly anthropogenic impacted areas and at the slightly urbanized sites.

Laboratory investigation of steam transmission in unsaturated clayey soil under osmotic potential

Liquids coming from different sources like wastewaters, agricultural and industrial activities and leakages of chemical substances often have high concentration of chemical compositions and the osmotic gradient generated around such sources causes a considerable transmission of the Contamination. The steam transmitted by non-polluted soils moves to polluted masses, causing an increase in the volume of pollution zone and movement of pollutants. Therefore, such physical and chemical processes should be taken into account in pollution transmission models. Using Crumb method, laboratory investigations were conducted on non-dispersive and dispersive clayey soil samples obtained from three areas in Zanjan Province of Iran. A simple experimental setup has been used and hereby introduced. The impact of osmotic force from salinities of 0.5, 1, and 1.5% on steam transmission in clayey soil was examined. Results indicate that for all samples between 5 to 15days, the moisture content increased in the pollutant zone and decreased in the non-pollutant area. Also it was observed that for dispersive clayey soil, movement of steam among layers was observed to be orderly and its amount was higher than that of non-dispersive clayey soil.

Uptake and distribution of copper, lead, and zinc in dandelions (Taraxacum officinale; Asteraceae) sampled from polluted and nonpolluted soils

Abstract We investigated the hypotheses that (a) differences in metal uptake exist between dandelion (Taraxacum officinale Weber; Asteraceae) clones sampled from unpolluted and polluted sites when grown in polluted media, and (b) differences in metal uptake into dandelion roots versus leaves exist for clones sampled from unpolluted and polluted sites when grown in polluted media. These hypotheses were tested by performing a series of reciprocal, greenhouse-planting experiments in which distinct dandelion clones (12 clones, identified by DNA fingerprinting, from each site type) sampled from two unpolluted and two polluted (relatively high copper [Cu], lead [Pb], and zinc [Zn] soil concentrations) sites were grown pairwise in both unpolluted (nutrient solution only) and polluted (nutrient solution + 120 mg kg−1 Cu, 700 mg kg−1 Pb, and 260 mg kg−1 Zn) media (N = 48 pairwise plantings for each medium type). Analyzing the entire data set (including unpolluted and polluted treatments), dandelion clones sampled ...

УЛААНБААТАР ХОТЫН ХӨРСНИЙ БОХИРДОЛ

According by soil investigation of Ulaanbaatar city area in 2012 soil heavy metal contamination generally was low. In some areas revealed anomaly high content of Chromium, Lead and Zink exceeding maximum allowed content. But this points a sporadic distributed not covered big area and 7.5-2.7 % of samples are exceeding standard level. The soil ammonium and sulfate content is high comparing with non-polluted pasture soils. Soil ammonium pollution more closely connected with big open markets and “ger horoolol” area. Primary source of sulfate content is air pollution and coal burning. Soil microbiological pollution, E.Coli and anaerobic bacteria level is high. The “ger horoolol” district area becoming main source of microbiological pollution. Improvement of solid waste management and “ger horoolol” area planning is challenging issue to solve a soil pollution problem of Ulaanbaatar city area.

Giant reed growth and effects on soil biological fertility in assisted phytoremediation of an industrial polluted soil

Phytoremediation is a cost-effective “green technology” that uses plants to improve the soil properties of polluted sites, preventing the dispersion of pollutants and reducing the mobility of potentially toxic elements (PTEs) through their adsorption and accumulation by roots or precipitation within the root zone. Being highly tolerant to pollutants and other abiotic stresses, giant reed (Arundo donax L.) is a suitable biomass crop for phytoremediation of contaminated soils.We report the results of a two-year open-air lysimeter study aimed at assessing the adaptability of giant reed to grow on industrial substrates polluted by Pb and Zn and at testing commercial humic acids from leonardite as improvers of plant performance. We evaluated giant reed potential for: 1) biomass production for energy or biomaterial recovery; 2) PTE phytoextraction and 3) soil fertility restoration. Chemical fertility was monitored by measuring soil C while soil biological fertility was estimated by quantifying the abundance of bacterial functional genes regulating nitrogen fixation (nifH) and nitrification (amoA).Giant reed above-ground growth on the polluted soils was slightly lower (−16%) than on a non-polluted soil, with a preferential storage of biomass in the rhizome acting as a survival strategy in limiting growing conditions. Humic acids improved plant stress tolerance and production levels. As aerial biomass (shoots) did not accumulate PTEs, the plant in question can be used for bioenergy or biopolymer production. In contrast, below-ground biomass (rhizomes) accumulated PTEs, and can thus be harvested and removed from soil to improve phytoremediation protocols and also used as industrial biofuel. Giant reed growth increased the abundance of N-cycling bacteria and soil C in the rhizospheric soil, as well as reduced soil Pb and Zn EDTA extractable fraction.

The impact of chemical pollution on the resilience of soils under multiple stresses: A conceptual framework for future research

Soils are faced with man-made chemical stress factors, such as the input of organic or metal-containing pesticides, in combination with non-chemical stressors like soil compaction and natural disturbance like drought. Although multiple stress factors are typically co-occurring in soil ecosystems, research in soil sciences on this aspect is limited and focuses mostly on single structural or functional endpoints. A mechanistic understanding of the reaction of soils to multiple stressors is currently lacking.Based on a review of resilience theory, we introduce a new concept for research on the ability of polluted soil (xenobiotics or other chemical pollutants as one stressor) to resist further natural or anthropogenic stress and to retain its functions and structure. There is strong indication that pollution as a primary stressor will change the system reaction of soil, i.e., its resilience, stability and resistance. It can be expected that pollution affects the physiological adaption of organisms and the functional redundancy of the soil to further stress. We hypothesize that the recovery of organisms and chemical-physical properties after impact of a follow-up stressor is faster in polluted soil than in non-polluted soil, i.e., polluted soil has a higher dynamical stability (dynamical stability=1/recovery time), whereas resilience of the contaminated soil is lower compared to that of not or less contaminated soil. Thus, a polluted soil might be more prone to change into another system regime after occurrence of further stress. We highlight this issue by compiling the literature exemplarily for the effects of Cu contamination and compaction on soil functions and structure.We propose to intensify research on effects of combined stresses involving a multidisciplinary team of experts and provide suggestions for corresponding experiments. Our concept offers thus a framework for system level analysis of soils paving the way to enhance ecological theory.

Effect of mycorrhizal inoculation on black and white poplar in a lead-polluted soil

A pot experiment was carried out to examine the effect of inoculation with arbuscular mycorrhizal fungi (originated from a soil polluted with Pb) on root mycorrhizal colonization, survival, growth and volume production of black and white poplar plants grown on polluted (Pb) and non-polluted soils. In July, mycorrhizal inoculation had no significant effect on stem growth and volume production of black and white poplar plants grown on polluted and non-polluted soils. In October, mycorrhizal inoculation improved only parameters of white poplar plants (survival on polluted soil; growth and volume production on polluted and non-polluted soils). Mycorrhizal inoculation increased the root colonization percentage of black and white poplar plants on both soils. Generally, black poplar plants had significantly better survival, root mycorrhizal colonization, stem growth and volume production than white poplar plants. Although mycorrhizal and non-mycorrhizal plants of black poplar on polluted soil had higher survival, growth and volume production than white poplar, however in white poplar mycorrhizal inoculation improved the efficiency of plants on polluted soil.

Heavy metal tolerant Pseudomonas protegens isolates from agricultural well water in northeastern Algeria with plant growth promoting, insecticidal and antifungal activities

The application of plant growth promoting bacteria (PGPB) with biocontrol activities as inoculants of crop plants against phytopathogenic fungi and insect pests provide a biological alternative to the use of agrochemicals. Two Pseudomonas protegens strains were isolated from agricultural well water in a heavy metal contaminated area near Bejaia, northeastern Algeria. The isolates S4LiBe and S5LiBe had 16S rRNA gene sequence similarities of 99.4%–99.7% with P. protegens CHA0T and other P. protegens strains. The phenotypic profiles tested with BIOLOG-GN2-microplates showed differences in 12 of 95 carbon sources tested, as compared to the type strain P. protegens CHA0T. The isolates S4LiBe and S5LiBe showed plant growth promoting potential which is commonly associated with the production of the phytohormone indole acetic acid and siderophores and the solubilization of insoluble phosphate. In addition, they produce chitinase and other polymer degrading enzymes. As the strains S4LiBe and S5LiBe were isolated from heavy metal polluted well water, they are resistant against several heavy metals (2.0 mM K2Cr2O7 and 3.0 mM CoSO4, HgSO4, CdSO4 8H2O and PbCl2), while the reference strain P. protegens CHA0T was very sensitive to Hg2+ and Cd2+ and had lower tolerance towards Co2+ and Pb2+. The isolates S4LiBe and S5LiBe were active in mycelial growth inhibition assays against Botrytis cinerea, Verticillium dahliae, Fusarium graminearum, Aspergillus niger and Aspergillus flavus (growth inhibition between 88% and 48%). Furthermore, S4LiBe and S5LiBe showed effective insecticidal activities, when tested in the Galleria injection assay and they were tested positive for the insect toxin gene fitD alike the reference strain CHA0T. Finally, inoculation of barley seeds with S5LiBe in non-polluted agricultural soil significantly stimulated the germination rate and growth of seedlings, with increased shoot length (11.96 cm ± 0.59), shoot and root fresh weight (0.10 g ± 0.009, 0.04 g ± 0.006), shoot and root dry weight (0.075 g ± 0.003, 0.03 g ± 0.007) as compared to non-inoculated plants (10.23 cm ± 0.84, 0.06 g ± 0.007, 0.025 g ± 0.006, 0.047 g ± 0.006, and 0.016 g ± 0.004, respectively). In heavy metal contaminated soil, inoculation with strain S5LiBe resulted in similar increase of germination rate and growth parameters of barley like in the non-polluted soil, while P. protegens CHA0T inoculated plants were not stimulated. Thus, the heavy metal tolerant isolates S4LiBe and S5LiBe have a potential as beneficial bacteria for agricultural application even in heavy metal polluted soils, e.g. for the stimulation of biomass crops. The demonstration of successful isolation from agricultural well water may open more ready access for a wide variety of this kind of beneficial bacteria for agricultural application.

Sex and heavy metals: Study of sexual dimorphism in response to soil pollution

In dioecious plants, males and females often show distinct morphological, physiological and life history traits as result of their different demands for reproduction. Such sexual dimorphism is likely to be accentuated under stressful conditions, such as that imposed by exposure to heavy metals. However little is known about the response of dioecious plants to stress by heavy metals. Here we use the dioecious herb Silene latifolia to investigate the growth and reproduction of males and females growing in soil polluted with either Cu or Cd. We also examined whether the sexes differed in the patterns of metal accumulation in their tissues. Patterns of biomass allocation to reproduction, roots, leaves and shoots (stem and leaves) were compared in male and female S. latifolia plants that were harvested after growing for 14 weeks in different soil conditions (non-polluted soil, Cu-polluted soil and Cd-polluted soil). In addition, patterns of metal accumulation between the sexes were also compared post-harvest by analysing the metal content in their tissues. Overall, metals decreased plants’ total dry mass allocated to leaves and to roots- particularly in males. Females accumulated more Cu in their tissues. However, this did not seem to correspond with females performing worse (in terms of growth and reproduction) than males when growing in soil polluted with this metal. Despite males and females having similar levels of Cd in their tissues, males seemed to have lower tolerance to this metal, as indicated by a lower total and leaf dry mass than females, and also by a lower number of flowers when growing in Cd-polluted soil. We also found contrasting differences in female seed production due to heavy metals, with number of seeds (but not mass) decreasing with Cu and increasing with Cd. Our results indicate the presence of sexual dimorphism in response to heavy metals, with the sexes differing in both patterns of accumulation and tolerance.

Influence of organic and inorganic amendments on cadmium sorption in a calcareous soil

AbstractA laboratory experiment was conducted to determine the benefits of some soil organic and inorganic amendments on cadmium (Cd) sorption capacity in non-polluted calcareous soil. The non-polluted soil was separately incubated with organic [municipal solid waste compost (MSWC), rice husk biochars prepared at 300°C (B300) and 600°C (B600)] and inorganic amendments (coal fly ash, CFA), zero valent iron (Fe

Ranking of mechanisms governing the phytoavailability of cadmium in agricultural soils using a mechanistic model

The objective of this study was to rank the mechanisms influencing the phytoavailability of cadmium (Cd) in agricultural soils. We developed a model that simulates the transport by diffusion and convection, the kinetics of sorption and complexation in solution and the root uptake of Cd. The ranking of mechanisms was performed by simulating the Cd2+ uptake by 1 cm2 root for 30 days for French agricultural soil characteristics. The initial Cd2+ concentration was the most influential parameter followed by the soil buffer power for Cd2+ and by the soil water content and impedance factor. The Cd2+ was generally strongly depleted at the root surface and the convection was almost negligible. In general, the Cd complex dissociation contributed little to the uptake due to a strong kinetics limitation. Conversely, the kinetics of sorption was little influential. The initial concentration and diffusion of Cd2+ were the dominant processes governing the phytoavailability in non-polluted soils. A model considering only the transport and sorption of Cd2+ without kinetics would be adequate to predict the phytoavailability. The particular situations where these simplifications do not hold (relative error >10 %) corresponded to a high supply of labile Cd complex toward plant roots.

Assessment of polycyclic aromatic hydrocarbons in biochar and biochar-amended agricultural soil from Southern Spain

The goal of this study was to determine if the application of four biochars produced from different feedstock leads to soil contamination with the 16 US Environmental Protection Agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in biochar-amended pots incubated under greenhouse conditions. The PAHs were extracted by Soxhlet and quantified by gas chromatography mass spectrometry in the biochars and in biochar-amended Calcic Cambisols on which Lolium perenne was grown under greenhouse conditions during 79 days. Three of the used biochars were produced by pyrolysis at 620 °C from wood chips, paper sludge, and sewage sludge, respectively. The fourth biochar was produced from old grapevine wood by the traditional kiln method. The Soxhlet extraction of the Σ16PAHs of pure biochars yielded between 959 ± 62 (sewage sludge biochar) and 2613 ± 1380 μg kg−1 (pine wood biochar) dry mass. The lowest abundance of PAHs of sewage sludge biochar is consistent with its very low content of organic carbon and the abundance of ashes. The PAH concentration of the wood biochar produced by kiln was six times higher than the wood biochar produced by fast pyrolysis, indicating that the biochar production process significantly affected the PAH levels. The unamended soil showed PAH levels typically for non-polluted soils (Σ16PAHs = 59 ± 4 μg kg−1). Addition of 10 t biochar ha−1 soil resulted in a lower increase of the 16 PAHs than expected for wood and paper sludge biochars, whereas for the soils amended with kiln wood biochar, the content of PAHs increased up to a factor of 10. Amendments of 20 and 40 t ha−1 increased PAH concentrations to values on the same order of magnitude than the predicted ones, except for pine wood biochar, where the concentrations were ten times greater than expected. The major divergences were found for high-molecular-weight PAHs. The production process of biochar affected significantly their PAH levels. The material carbonized in traditional kilns contained the greatest amounts of PAHs. Sampling procedures for biochar-amended soils should be carefully described for future legislation guidelines to guarantee quality biochar application.

Screening for new accumulator plants in potential hazards elements polluted soil surrounding Peruvian mine tailings

Tailings usually provide an unfavorable substrate for plant growth because of their multi-stress environment. Plants growing on naturally metal-enriched soils are of particular interest in this perspective, since they are genetically tolerant to high metal concentrations and have an excellent adaptation to extreme conditions. Soil and plant samples were taken in Peru, at a polymetallic mine (mainly Ag, Pb and Cu) in Cajamarca Province, Hualgayoc district. Top soils (0–20cm) were analyzed for physical and chemical properties by standard methods. Total As, Cu, Pb and Zn concentrations in top soils were determined by ICP–OES. Similar metals in plants were analyzed separately (aerial and root system) by ICP–MS. Translocation Factor (TF) and Shoot Accumulation Factor (SAF) were determined to assess the tolerance strategies developed by these species and to evaluate their potential for phytoremediation purposes. The non-polluted soils had near neutral pH (6.8±0.1), a great content of organic carbon (42±4.0gkg−1) and a silt loamy texture. Soil and plant samples were taken at four locations (CA1, CA2, CA3, CA4) as well as the local reference topsoil (CA0). The range of total soil values in mg kg−1 is as follows: As 280–1029; Cu 256–2070; Pb 3992–16,060 and Zn 11,550–28,059, respectively. Unusual elevated concentrations of Pb (over 1000mgkg−1) and TF greater than one were detected in shoots of six different plants species (Ageratina sp., Achyrocline alata (Kunth) DC., Cortaderia hapalotricha Pilg., Epilobium denticulatum Ruiz & Pav., Taraxacum officinale Weber and Trifolium repens Walter). Ageratina sp and E. denticulatum also showed elevated concentrations of Zn (over 10,000mgkg−1) and TF greater than one in some studied locations. However, the SAF was smaller than one. Controlled-environment studies must be performed to definitively confirm the Pb hyperaccumulation character of the cited plant species.

Microbial indicators for assessing the adverse impact of technical-grade hexachlorocyclohexane on soil quality

Technical-grade hexachlorocyclohexane (HCH) has been widely used for human health and agricultural purposes. Consequently, HCH residues have entered the soil ecosystem with concomitant deleterious effects on soil quality. The aim of this study was to assess the impact of HCH on soil microbial properties as biological indicators of soil quality. To this end, non-polluted soil was spiked with different amounts of a heavily HCH-polluted soil in order to obtain a concentration gradient between 0 and 1,500 mg HCH kg&lt;sup&gt;-1&lt;/sup&gt; dry matter soil. The mixtures were incubated under laboratory conditions for 2 months. Dehydrogenase activity, fluorescein diacetate hydrolysis activity (FDA), basal respiration, substrate-induced respiration (SIR), microbial biomass carbon, metabolic potential, and the soil quality index were negatively affected by increasing HCH concentrations in soil, in many cases following an exponential pattern. FDA and SIR appear &lt;em&gt;a priori&lt;/em&gt; suitable indicators for the impact of HCH on soil microbial properties and, hence, soil quality.

The effect of zeolite,bentonite and sepiolite minerals onheavy metal uptake by sunflower

Mining, industrial and agricultural activities can result in considerable soil pollution by heavy metals (HMs). One of the methods to control this pollution is application of adsorbent minerals. The purpose of this study was to compare the effects of adsorbent minerals (bentonite, zeolite and sepiolite) on transfer of some heavy metals (i.e., Pb, Zn and Cd) from soil to tissues of sunflower (Heliantus annuus L.). Treatments included: Non-polluted soil, HM-polluted soil, polluted soil + bentonite, polluted soil + zeolite, and polluted soil + sepiolite. Sunflower seeds were planted in different pots containing the above treated soils. After 70 days of growth, plants were harvested and HMs content was measured. Results revealed that the uptake of HMs from non-polluted soil was lower than that of other treatments. In the polluted soil + sepiolite treatment, the added sepiolite increased plant Cd and Zn uptake by 0.37 and 7.17 mg/kg, respectively. However, the differences in HMs uptake were not significant for other treatments. Zeolite addition decreased plant uptake of Zn and Cd by about 12 and 0.21 mg/kg, respectively, while bentonite addition reduced Pb uptake by about 3.05 mg/kg, without any significant difference for the other treatments. Zn uptake was higher by about 12.2 mg/kg in plant shoots as compared to plant roots. On the contrary, the roots took up higher amounts of Cd and Pb, as compared to the shoots. Despite high concentration of the HMs in the polluted soils, considerable tendency of sunflower for uptake, and a high adsorption capacity of the applied minerals, the HMs uptake by sunflower and surface adsorption by the minerals were very low, probably due to HMs precipitation in the soil.

Belowground fungal communities in pioneer Scots pine stands growing on heavy metal polluted and non-polluted soils

The impact of soil metal pollution on plant communities has been studied extensively in the past. However, very little is known about the fungal species that co-occur with these plant communities on metal polluted soils. We characterized the belowground fungal community in a heavy metal polluted and a non-polluted soil using 454 pyrosequencing. The fungal communities at both study sites were shown to consist mainly of the same ectomycorrhizal species, but a consistent shift in the relative abundances of these species was observed, whereas no differences in fungal diversity were found. In metal polluted soil, root tips of young pines were initially largely colonized by stress-tolerant dark Ascomycota that were mostly replaced by metal-tolerant Basidiomycota within 2 years. Compared to older forests, a low belowground fungal diversity was observed in the two pioneer stands.