Changes in biological activity of turf-podzolic soil of different mechanical composition contaminated with heavy metals

It has been shown that soil pollution with heavy metals (copper, nickel) lead to negative changes in parameters characterizing potential biological activity of soil (nitrogen-fixation, breath, invertase activity, bacteria and fungi count). More profound changes were observed in sandy soil compared to loamy soil. A direct relationship of these effects with the content of mobile forms of heavy metals in soil has been established. For the comparative and prognostic investigation of the danger of soil pollution with heavy metals it has been suggested to use a coefficient of differences in the content of mobile forms and a coefficient of biological effect.     

Evaluation of the effects of coal fly ash amendments on the toxicity of a contaminated marine sediment

Approaches for cleaning up contaminated sediments range from dredging to in situ treatment. In this study, we discuss the effects of amending reference and contaminated sediments with coal fly ash to reduce the bioavailability and toxicity of a field sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Six fly ashes and a coconut charcoal were evaluated in 7-d whole sediment toxicity tests with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia). Fly ashes with high carbon content and the coconut charcoal showed proficiency at reducing toxicity. Some of the fly ashes demonstrated toxicity in the reference treatments. It is suspected that some of this toxicity is related to the presence of ammonia associated with fly ashes as a result of postoxidation treatment to reduce nitrous oxide emissions. Relatively simple methods exist to remove ammonia from fly ash before use, and fly ashes with low ammonia content are available. Fly ashes were also shown to effectively reduce overlying water concentrations of several PAHs. No evidence was seen of the release of the metals cadmium, copper, nickel, or lead from the fly ashes. A preliminary 28-d polychaete bioaccumulation study with one of the high-carbon fly ashes and a reference sediment was also performed. Although preliminary, no evidence was seen of adverse effects to worm growth or lipid content or of accumulation of PAHs or mercury from exposure to the fly ash. These data show fly ashes with high carbon content could represent viable remedial materials for reducing the bioavailability of organic contaminants in sediments.     

Effect of soil amendments on radiocesium transfer to alfalfa

Greenhouse experiments were carried out to evaluate the effect of different soil-based countermeasures on radiocesium transfer to Medicago saliva (alfalfa) grown on artificially contaminated loamy-clayey soil. Various rates of potassium, ammonium, and Prussian Blue supplements were applied, and the uptake of radiocesium by control and treated alfalfa plants was monitored during four growth periods. Transfer factors ranging between 0.06 and 0.02 were determined for control plants. Application of potassium at rates higher than 0.1 meq per 100 g soil was found to suppress radiocesium uptake, the effect being more pronounced at increasing fertilization rates. On the contrary, soil treatment with ammonium enhanced the bio-accumulation of radiocesium, indicating that Cs+ ions, previously unavailable to plant roots, were released from soil particles. Prussian Blue supplements had practically no effect on soil-to-alfalfa transfer of the radionuclide.     

Extraction of spiked metals from contaminated coastal sediments: a comparison of different methods

Various extraction methods have been developed to assess metal bioavailability from sediments. In this study, we compared the extraction of Cd, Cr, and Zn from contaminated sediments using different extractants (normal seawater, acidic seawater of pH = 5. seawater with 1% sodium dodecyl sulfate [SDS], and gut digestive fluids collected in vitro from deposit-feeding peanut worm Sipunculus nudus) coupled with concurrent metal speciation measurements. The influences of sediment aging on metal extraction were also examined using radiotracer-spiked techniques. Sediments aging up to 100 d did not significantly affect the partitioning of spiked Cd and Cr in different geochemical phases, but the spiked Zn was partitioned more into the reducible fraction and less into the carbonate phase with increasing sediment aging. There was a major difference in the partitioning into different geochemical phases between the spiked metals and the native metals within the 100-d sediment aging. The difference between the spiked and native Cd and Zn extraction using gut juices was somewhat smaller than the strong geochemical contrast. Metals bound with the anoxic sediments were hardly extracted by different extractants. There was a significant relationship between the extraction of spiked Cd and its distribution in the exchangeable phase (positive correlation) or in the reducible phase (negative correlation). For Cr and Zn, extraction was not correlated with their partitioning in any of the geochemical phases. Further, extraction of all three metals by digestive gut fluids was not correlated with the concentrations of simultaneously extractable metals (SEM), nor with the difference between SEM and acid volatile sulfide (AVS). Our study suggests that there were large differences in extraction among metals using different extractants and only Cd extraction was significantly related to its geochemical speciation in sediments.     

Ecological and hygienic evaluation of microbiological process in the soil contaminated by anion surfactants and heavy metals

Disorders in microbiocenosis and biological activity of different types of soil were studied in a laboratory model experiment and the survival of reference and pathogenic microorganisms exposed to sulfonol and lead was evaluated. The most sensitive tests for such studies are evaluation of the number of nitrifiable bacteria, nitrifying, proteolytical, dehydrogenase, and cellulase activities, and survival of Salmonella and lactose-positive Escherichia coli in soil.     

Heavy metals: soil characteristics and methods of evaluating parameters for defining "contaminated soils"

The excessive content of toxic elements in the human environment is associated with the etiology of a number of diseases. Soils' pollutants decontamination regards the main industrialised countries. Heavy metals represent the main problem for soil pollution characterisation. The first approach for pollution evaluation is the determination of total metal concentration; the evaluation of their bioavailability is required for a correct knowledge of the environmental risk. In the present work is shown the procedure to evaluate the sites, which require decontamination and which need the following data: knowledge of the threshold for each metal in the soil and its range, chemical analysis of the components, determination of bioavailability and soil destination. The bioavailability is easily calculated by the procedure of aimed extractions.     

镉污染土壤植物萃取技术的研究进展

植物萃取是指在受重金属污染的土壤上连续的种植专性植物并收割植物茎叶作离地处理 ,以降低土壤中的重金属浓度的新兴技术。利用此方法对镉污染土壤进行原位修复具有成本低、环境可持续性的优点。综述了近年来这一领域内的研究进展及其商业应用的可行性分析 ,并展望了此技术在我国的应用前景。     

植物-微生物联合修复污染土壤的研究

目的 探讨植物-微生物联合修复污染土壤的效果。方法 土培盆栽试验。结果 与供试微生物菌群较适合的植物是玉米，其次是芥菜；适合玉米的最适微生物菌的浓度是100mg／kg，适合芥菜的最适微生物菌的浓度是50mg／kg。结论 植物一微生物联合修复是生物修复的一种有效的形式，其关键是寻找较适合的植物一微生物匹配组合。     

Evaluation of the bacteriological safety of wares made from different metals

The determination of the integral toxicity of a liquid after its contact with different metallic wares could provide a comparative assessment of the hazards of this ware to living organisms. The distilled water and physiological solution exposed to silverware even for a short period of time (15 min) proved to be deleterious to the specially selected bacterial strains differing in their resistance to different chemical substances while aluminum ware was quite harmless to them after their long (4-day) standing of liquids.     

Evaluation of bacterial flora in contaminated soil as a countermeasure against H2S gas production

Gas productions in illegal dumping sites and waste landfills have caused serious problems. The gas production was induced by bacterial flora inhabited soils. In order to construct a culture independent evaluation system of the soil bacteria, bacterial communities were analyzed quantitatively and qualitatively, about 16 soil samples at 4 sites, both using culture and culture-independent methods. The real time PCR method was developed for counting total bacterial number. Sequencing analysis of 16S rDNA amplified by a direct PCR method revealed that non-spore forming sulfate reducing bacteria and sulfur-oxidizing bacteria were detected at a similar frequency at an illegal dumping site near mountains. On the other hand, spore-forming sulfate reducing bacteria and Clostridium sp. were mainly detected in deep samples at reclaimed landfills from the sea, whereas sulfur-oxidizing bacteria was hardly detected. The result regarding sulfate-reducing bacteria was confirmed also by an anaerobic culture method. Culture-independent molecular analyses of soil bacteria would give us useful information for prediction of gas production and for the evaluation of soil equilibrium.     

Changes in toxicity and bioavailability of lead in contaminated soils to the earthworm Eisenia fetida (Savigny 1826) after bone meal amendments to the soil

The effect of bone meal (Ca5(PO4)3OH) amendments on lead (Pb) bioavailability to Eisenia fetida (Savigny 1826) was investigated. A standard uncontaminated soil was amended with Pb(NO3)2 solution to give Pb concentrations of 7,000 microg/g of soil. After one week, bone meal was added to one half of the soil in the ratio 1:20 bone meal:soil. Immediately after addition of the bone meal, survival times of E. fetida were 23 and 41 h in the bone meal-free and bone meal-amended soil, respectively. Twenty-eight days after addition of the bone meal, survival times of Eisenia fetida were 67 h in the bone meal-free soil and more than 168 h in the bone meal-amended soil. In a second experiment, a standard Organisation for Economic Co-operation and Development reproduction toxicity test was carried out, but in addition to Pb(NO3)2 solution, bone meal was added to the soil in the ratio 1:20 bone meal:soil. The bone meal-free soil was left for five weeks before addition of E. fetida. In the bone meal-amended soil, bone meal was added to the soil one week after addition of the Pb. The soil was left for a further four weeks before addition of Eisenia fetida. Calculated toxicities were significantly lower for the bone meal-amended soil than those calculated for the bone meal-free soil. Twenty-eight-day median lethal concentrations (LC50s; concentration that is statistically likely to kill 50% of the exposed test organism within a given time period +/- 95% confidence intervals) of Pb were 4,379 +/- 356 microg/g of soil for bone meal-free soil and 5,203 +/- 401 microg/g of soil for bone meal-amended soil. Twenty-eight-day median effect concentrations (EC50s; concentration causing a reduction by 50% of a stated parameter) of Pb for weight change were 1,408 +/- 198 microg/g of soil for bone meal-free soil and 3,334 +/- 731 microg/g of soil for bone meal-amended soil and EC50s for cocoon production were 971 +/- 633 microg/g of soil for bone meal-free soil and 1,814 +/- 613 microg/g of soil for bone meal-amended soil. Significant mortalities occurred at Pb concentrations of 2,000 microg/g of soil in the bone meal-free soil and 5,000 microg/g of soil in the bone meal-amended soil. Earthworm Pb body load was lower in the bone meal-treated soil than in the bone meal-free soil up to a Pb concentration of 5,000 microg/g of soil. Earthworm Pb body load was approximately 100 microg/g of worm in surviving earthworms in both experiments when significant mortality occurred. Water and diethylenetriamine pentaacetic acid-extractable soil Pb showed good correlations with earthworm Pb body load. These extractions could be used as estimates for Pb bioavailability.     

Trace metals in sediments and potential availability to Anadara granosa

Trace metals in the sediments non-residual fraction and their relative abundance in various sedimentary components from the culture bed of Anadara granosa were investigated. High levels of Cd (40%), Ni (40%), and Pb (43%) were associated with the sediment exchangeable phase (EP). The sediment moderately reducible phase (MRP) was more predominant than the easily reducible phase (ERP) and the organic sulphide phase (OSP) in the sorption of available trace metals. However, this area was not considered to be heavily impacted by trace metal pollution. Since there was no significant concentration gradients observed in sediments and bivalves collected from all stations, trace metal enrichment factors were determined. A. granosa collected from this area was enriched by Zn, Cu, Pb, Ni, Cd, and Ni.     

Short-term ecological risks of depositing contaminated sediment on arable soil

Sediments act as sinks of suspended material from surface water. Dredging of regional waters and subsequent disposal of the sediment on soil may lead to contamination of the soil, in some cases resulting in exceedance of soil quality standards. Soil quality standards are based on total concentrations. Total levels, however, do not always give an indication of adverse effects in soil ecosystems. Instead, truly bioavailable concentrations should be used as indicators. In this study we aim to test a set of suited indicators. We carried out partition and accumulation assays with metals and polycyclic aromatic hydrocarbons (PAHs) in soils and mixtures of soil and sediment, as well as a limited number of toxicity bioassays. We also investigated the rate of disappearance of PAHs from mixtures of sediments and soils. The experiments confirm that total levels indeed are not indicative of truly occurring toxic effects: mixing of highly contaminated sediments with soil hardly gave rise to either additional accumulation of metals and PAHs or excess toxicity. This indicates that the bioavailability of the metals and PAHs present in the sediment is limited. This general finding is confirmed by the low rate of disappearance of PAHs from the mixtures. It is concluded that inclusion of the aspects of bioavailability, mixture toxicity, and degradation, in the way described in this report, will solve the major limitations of the current methodology of classification of contaminated sediments.