Laboratory studies on Escherichia coli O157:H7 survival in soils from four different land use types: forest, tea plantation, bamboo grove, and vegetable garden were investigated at 25 ± 1 °C with the field capacity (soil water content at −33 kPa). Results showed that E. coli O157:H7 declined quickly in the test soils, but its survival dynamics varied in the soils under different land use types. The survival time needed to reach the detection limit (td) in the test soils ranged from 2.1 to 3.6 days, with slightly longer tdvalues being observed in soils from the bamboo grove. Stepwise multiple regression analysis revealed that the tdvalues were shorter in sandy, lower pH, and lower organic carbon content soils. Different E. coli O157:H7 survival time in the soils under different land uses suggests that it is important to adapt proper management practices for reducing the potential risks of pathogen contamination when diary manure is applied to agricultural land.

Most persistent organic pollutants, due to their hydrophobic properties, accumulate in aquatic sediments and represent a high risk for sediment quality. To assess the toxicity of hydrophobic pollutants, a novel approach was recently proposed as an alternative to replace, refine and reduce animal experimentation: the medaka embryo–larval sediment contact assay (MELAc). This assay is performed with Japanese medaka embryos incubated on a natural sediment spiked with the compound being tested. With the aim of improving this assay, our study developed a reference exposure protocol with an artificial sediment specifically designed to limit natural sediment composition uncertainties and preparation variability. The optimum composition of the new artificial sediment was tested using a model polycyclic aromatic hydrocarbon (PAH), fluoranthene. The sediment was then validated with two other model PAHs, benz[a]anthracene and benzo[a]pyrene. Various developmental end points were recorded, including survival, embryonic heartbeat, hatching delay, hatching success, larval biometry and abnormalities. The final artificial sediment composition was set at 2.5 % dry weight (dw) Sphagnum peat, 5 % dw kaolin clay and 92.5 % dw silica of 0.2- to 0.5-mm grain size. In contrast with natural sediments, the chemical components of this artificial matrix are fully defined and readily identifiable. It is totally safe for fish embryos and presents relatively high sorption capacities for hydrophobic compounds. Studies with other hydrophobic and metallic contaminants and mixtures should be performed to further validate this artificial sediment.

Pot culture experiments were conducted in a glasshouse to evaluate the effects of four efficient Cr(VI)-reducing bacterial strains (SUCR44, SUCR140, SUCR186, and SUCR188) isolated from rhizospheric soil, and four arbuscular mycorrhizal fungi (AMF—Glomus mosseae, G. aggregatum, G. fasciculatum, and G. intraradices) alone or in combination, on Zea mays in artificially Cr(VI)-amended soil. Presence of a strain of Microbacterium sp. SUCR140 reduced the chromate toxicity resulting in improved growth and yields of plants compared to control. The bioavailability of Cr(VI) in soil and its uptake by the plant reduced significantly in SUCR140-treated plants; the effects of AMF, however, either alone or in presence of SUCR140 were not significant. On the other hand, presence of AMF significantly restricted the transport of chromium from root to the aerial parts of plants. The populations of AMF chlamydospores in soil and its root colonization improved in presence of SUCR140. This study demonstrates the usefulness of an efficient Cr(VI)-reducing bacterial strain SUCR140 in improving yields probably through reducing toxicity to plants by lowering bioavailability and uptake of Cr(VI) and improving nutrient availability through increased mycorrhizal colonization which also restricted the transport of chromium to the aerial parts.

Dufulin is a newly developed antiviral agent (or pesticide) that activates systemic acquired resistance of plants. This pesticide is widely used in China to prevent abroad viral diseases in rice, tobacco and vegetables. In this study, the potential impacts such as soil type, moisture, temperature, and other factors on Dufulin degradation in soil were investigated. Degradation of Dufulin followed the first-order kinetics. The half-life values varied from 2.27 to 150.68 days. The dissipation of Dufulin was greatly affected by soil types, with DT₅₀(Degradation half time) varying between 17.59, 31.36, and 43.32 days for Eutric Gleysols, Cumulic Anthrosols, and Dystric Regosols, respectively. The elevated moisture accelerated the decay of Dufulin in soil. Degradation of Dufulin increased with temperature and its half-life values ranged from 16.66 to 42.79 days. Sterilization of soils and treatment with H₂O₂resulted in a 6- and 8-fold decrease in degradation rates compared to the control, suggesting that Dufulin degradation was largely governed by microbial processes. Under different light spectra, the most effective degradation occurred with 100-W UV light (DT₅₀ = 2.27 days), followed by 15-W UV light (DT₅₀ = 8.32 days) and xenon light (DT₅₀ = 14.26 days). Analysis by liquid chromatography-mass spectroscopy (LC-MS) revealed that 2-amino-4-methylbenzothiazole was one of the major decayed products of Dufulin in soils, suggesting that elimination of diethyl phosphate and 2-fluorobenzaldehyde was most like the degradation pathway of Dufulin in Eutric Gleysols.

Air pollutants are transported by dry deposition, wet deposition, and gas exchange accumulated in soil. Therefore, soil is an important environmental medium reflecting the level and the spatial distribution of air pollutants such as polybrominated diphenyl ethers (PBDEs) and heavy metals. Soil concentrations of seven PBDE congeners and 21 trace elements were determined in a heavily industrialized region (Dilovasi) in Kocaeli, Turkey. At all sites, Σ₇PBDE concentrations ranged from 0.70 to 203 with a mean value of 26.3 μg kg⁻¹(dry weight). The congener profiles and mass inventories of PBDEs and their interactions with soil organic matter (SOM) were also investigated. BDE-209 was the dominant congener at all sites, followed by BDE-99 and/or -47. The estimated inventory of PBDEs for the Dilovasi district was 310 kg. However, there are several additional industrial regions in Kocaeli city. Considering the total land area, the potential inventory would be much larger for this city. The relationship between the PBDE concentrations in soil and SOM content indicated that factors other than soil properties have a greater influence on soil concentrations. Crustal enrichment factors (EFs) were determined; correlation analysis and factor analysis (FA) were also applied to generated data set to identify and apportion the sources polluting the soil. Sn, Mn, Ca, As, Zn, Pb, and Cd had significantly high average EF values, indicating that their soil concentrations were mainly influenced by anthropogenic activities. In FA, six factors were extracted with a cumulative variance of 84.4 % and industrial activities and traffic were found to be the main factors affecting the soil profile.

The present study explores the tolerance and metal removal response of a well-developed 2-week-old Phormidium mat after long-term exposure to Cu²⁺-enriched medium. Cu²⁺enrichment inhibited increase in mat biomass in a concentration-dependent manner. Mat area and the number of entrapped air bubbles decreased as Cu²⁺concentration increased in the medium. Decrease in number of air bubbles obviously reflects the adverse effect of Cu²⁺on photosynthetic performance of the mat. Metal enrichment did not substantially alter the amount of pigments, such as chlorophyll a, chlorophyll b, carotenoids, and phycocyanin, in the mat. Enhancement of Cu²⁺concentration in the medium led to changes in species composition of the test mat; however, Phormidium bigranulatum always remained the dominant organism. Relative share of green algae and some cyanobacterial taxa, namely, Lyngbya sp. and Oscillatoria tenuis, in the mat were increased by Cu²⁺enrichment. The mat successfully removed 80 to 94 % Cu²⁺from the growth medium containing 10 to 100 μM Cu²⁺. Extracellular polysaccharides, whose share increased in the mat community after metal addition, seem to have contributed substantially to metal binding by the mat biomass.

Land use has obvious influence on surface water quality; thus, it is important to understand the effects of land use patterns on surface water quality. This study explored the relationships between land use patterns and stream nutrient levels, including ammonium-N (NH₄⁺-N), nitrate-N (NO₃⁻-N), total N (TN), dissolved P (DP), and total P (TP) concentrations, in one forest and 12 agricultural catchments in subtropical central China. The results indicated that the TN concentrations ranged between 0.90 and 6.50 mg L⁻¹and the TP concentrations ranged between 0.08 and 0.53 mg L⁻¹, showing that moderate nutrient pollution occurred in the catchments. The proportional areal coverages of forests, paddy fields, tea fields, residential areas, and water had distinct effects on stream nutrient levels. Except for the forest, all studied land use types had a potential to increase stream nutrient levels in the catchments. The land use pattern indices at the landscape level were significantly correlated to N nutrients but rarely correlated to P nutrients in stream water, whereas the influence of the land use pattern indices at the class level on stream water quality differentiated among the land use types and nutrient species. Multiple regression analysis suggested that land use pattern indices at the class level, including patch density (PD), largest patch index (LPI), mean shape index (SHMN), and mean Euclidian nearest neighbor distance (ENNMN), played an intrinsic role in influencing stream nutrient quality, and these four indices explained 35.08 % of the variability of stream nutrient levels in the catchments (p<0.001). Therefore, this research provides useful ideas and insights for land use planners and managers interested in controlling stream nutrient pollution in subtropical central China.

There is no research published sofar on managements that could bioremediate hypersaline soils and water polluted with hydrocarbons. The objective of this study was to assess the effect of vitamin amendment on hydrocarbon removal by microorganisms indigenous to such hypersaline environments. We used in this study ten hydrocarbonoclastic bacterial species and five archaeal species that had been isolated by the conventional plating method on media containing oil as a sole carbon source, from a hypersaline (3–4 M NaCl) coastal area in Kuwait, and characterized by sequencing of their 16S rRNA coding genes. The oil and pure hydrocarbon consumption was measured by gas–liquid chromatography. The oil and pure hydrocarbon consumption potential of all microorganisms in media with hypersalinity was enhanced by vitamin fertilization. This was true for individual microorganisms in pure cultures as well as for microbial consortia in hypersaline soil and water samples used as inocula. Most effective vitamins were thiamin, pyridoxine and vitamin B₁₂. Vitamin fertilization using vitamin rich wastes or byproducts could be an effective practice for enhancing bioremediation of oil contaminated hypersaline environments.

Field samples and a 9-week glasshouse growth trial were used to investigate the accumulation of mining derived arsenic (As) and antimony (Sb) in vegetable crops growing on the Macleay River Floodplain in Northern New South Wales, Australia. The soils were also extracted using EDTA to assess the potential for this extractant to be used as a predictor of As and Sb uptake in vegetables, and a simplified bioaccessibility extraction test (SBET) to understand potential for uptake in the human gut with soil ingestion. Metalloids were not detected in any field vegetables sampled. Antimony was not detected in the growth trial vegetable crops over the 9-week greenhouse trial. Arsenic accumulation in edible vegetable parts was <10 % total soil-borne As with concentrations less than the current Australian maximum residue concentration for cereals. The results indicate that risk of exposure through short-term vegetable crops is low. The data also demonstrate that uptake pathways for Sb and As in the vegetables were different with uptake strongly impacted by soil properties. A fraction of soil-borne metalloid was soluble in the different soils resulting in Sb soil solution concentration (10.75 ± 0.52 μg L–¹) that could present concern for contamination of water resources. EDTA proved a poor predictor of As and Sb phytoavailability. Oral bioaccessibility, as measured by SBET, was <7 % for total As and <3 % total Sb which is important to consider when estimating the real risk from soil borne As and Sb in the floodplain environment.

A greenhouse experiment was carried out to investigate the single effect of benzo[a]pyrene (B[a]P) or chromium (Cr) and the joint effect of Cr–B[a]P on the growth of Zea mays, its uptake and accumulation of Cr, and the dissipation of B[a]P over 60 days. Results showed that single or joint contamination of Cr and B[a]P did not affect the plant growth relative to control treatments. However, the occurrence of B[a]P had an enhancing effect on the accumulation and translocation of Cr. The accumulation of Cr in shoot of plant significantly increased by ≥ 79 % in 50 mg kg⁻¹Cr–B[a]P (1, 5, and 10 mg kg⁻¹) treatments and by ≥ 86 % in 100 mg kg⁻¹Cr–B[a]P (1, 5, and 10 mg kg⁻¹) treatments relative to control treatments. The presence of plants did not enhance the dissipation of B[a]P in lower (1and 5 mg kg⁻¹) B[a]P contaminated soils; however, over 60 days of planting Z. mays seemed to enhance the dissipation of B[a]P by over 60 % in 10 mg kg⁻¹single contaminated soil and by 28 to 41 % in 10 mg kg⁻¹B[a]P co-contaminated soil. This suggests that Z. mays might be a useful plant for the remediation of Cr–B[a]P co-contaminated soil.