Risk assessment of heavy metals pollution in agricultural soils of siling reservoir watershed in Zhejiang Province, China.

Presence of heavy metals in agriculture soils above the permissible limit poses threats to public health. In this study, concentrations of seven metals were determined in agricultural soils from Yuhang county, Zhejiang, China. Multivariate statistical approaches were used to study the variation of metals in soils during summer and winter seasons. Contamination of soils was evaluated on the basis of enrichment factor (EF), geoaccumulation index (I(geo)), contamination factor (C(f)), and degree of contamination (C(deg)). Heavy metal concentrations were observed higher in winter as compared to summer season. Cr and Cd revealed random distribution with diverse correlations in both seasons. Principal component analysis and cluster analysis showed significant anthropogenic intrusions of Zn, Cd, Pb, Cr, and Cu in the soils. Enrichment factor revealed significant enrichment (EF > 5) of Zn, Cd, and Pb, whereas geoaccumulation index and contamination factor exhibited moderate to high contamination for Zn, Cr, Cd, and Pb. In light of the studied parameters, permissible limit to very high degree of contamination (C(deg) > 16) was observed in both seasons.

Biotoxicity assessment of pyrene in soil using a battery of biological assays.

A test battery, composed of a range of biological assays, was applied to evaluate the ecological health of soil aged for 69 days and spiked with a range of pyrene levels (1.04, 8.99, 41.5, 72.6, 136, and 399 µg g(-1) dry soil; Soxhlet-extracted concentrations after 69 days of aging). Chinese cabbage (Brassica rapa), earthworm (Eisenia fetida), and bacteria (Vibrio fischeri) were used as test organisms to represent different trophic levels. Among the acute ecotoxicity bioassays used, the V. fischeri luminescence inhibition assay was the most sensitive indicator of pyrene toxicity. We observed >8 % light inhibition at the lowest concentration (1.04 µg g(-1)) pyrene, and this inhibition increased to 60 % at 72.6 µg g(-1). The sensitivity ranking for toxicity of the pyrene-contaminated soil in the present study was in the following decreasing order: root elongation of Chinese cabbage < earthworm mortality (14 days) < earthworm mortality (28 days) < luminescence inhibition (15 min) < luminescence inhibition (5 min). In addition, genotoxic effects of pyrene were also evaluated by using comet assay in E. fetida. The strong relationship between DNA damage and soil pyrene levels showed that comet assay is suitable for testing the genotoxicity of pyrene-polluted soil. In addition, tail moment was well correlated with soil pyrene levels (r (2) = 0.99). Thus, tail moment may be the most informative DNA-damage parameter representing the results of comet assay. Based on these results, the earthworm DNA damage assay and Microtox test are rapid and sensitive bioassays and can be used to assess the risk of soil with low to high levels of hydrocarbon pollution. Furthermore, an analysis of the toxic effects at several trophic levels is essential for a more comprehensive understanding of the damage caused by highly contaminated soil.

[Applications of soil metaproteomics in soil pollution assessment: a review].

Soil microbial indicator is one of the important biological indicators in evaluating the extent of soil contamination. In recent years, with the development of molecular biology, many studies have focused on the ecological functions of soil microorganisms by using metagenomics, metatranscriptome and metaproteomics. Relative to metagenomics and metatranscriptome, soil metaproteomics aims to investigate the spatial and temporal changes of the proteins extracted from soil as well as the functional components of soil microbial genomic expression products, which is more conclusive to explore the ecological functions of soil microbes and their roles in soil pollutants transportation and transformation. Therefore, soil metaproteomics has great potential in soil pollution assessment. Currently, soil metaproteomics is still at its infancy stage, while soil protein extraction method is one of the key factors restraining the potential application of soil metaproteomics. In this paper, the advantages and disadvantage of soil metaproteomics in soil pollution assessment were reviewed, with the focus on the comparison of different soil protein extraction methods. In combining with case studies, the feasibility and limits of soil proteins as an indicator for soil pollution assessment were analyzed. In addition, the future research perspectives on the development of soil metaproteomics were discussed.

Assessment of phenanthrene bioavailability in aged and unaged soils by mild extraction.

It has become apparent that the threat of an organic pollutant in soil is directly related to its bioavailable fraction and that the use of total contaminant concentrations as a measure of potential contaminant exposure to plants or soil organisms is inappropriate. In light of this, non-exhaustive extraction techniques are being investigated to assess their appropriateness in determining bioavailability. To find a suitable and rapid extraction method to predict phenanthrene bioavailability, multiple extraction techniques (i.e., mild hydroxypropyl-ß-cyclodextrin (HPCD) and organic solvents extraction) were investigated in soil spiked to a range of phenanthrene levels (i.e., 1.12, 8.52, 73, 136, and 335 µg g( - 1) dry soil). The bioaccumulation of phenanthrene in earthworm (Eisenia fetida) was used as the reference system for bioavailability. Correlation results for phenanthrene suggested that mild HPCD extraction was a better method to predict bioavailability of phenanthrene in soil compared with organic solvents extraction. Aged (i.e., 150 days) and fresh (i.e., 0 day) soil samples were used to evaluate the extraction efficiency and the effect of soil contact time on the availability of phenanthrene. The percentage of phenanthrene accumulated by earthworms and percent recoveries by mild extractants changed significantly with aging time. Thus, aging significantly reduced the earthworm uptake and chemical extractability of phenanthrene. In general, among organic extractants, methanol showed recoveries comparable to those of mild HPCD for both aged and unaged soil matrices. Hence, this extractant can be suitable after HPCD to evaluate risk of contaminated soils.

Assessment of pyrene bioavailability in soil by mild hydroxypropyl-ß-cyclodextrin extraction.

Bioavailability of organic pollutants in soil is currently a much-debated issue in risk assessment of contaminated sites. Ecorisk of an organic pollutant in soil is strongly influenced by the properties of the soil and its contamination history. To evaluate the effect of aging on the availability of pyrene, earthworm (Eisenia fetida) accumulation and chemical extraction by exhaustive and nonexhaustive techniques in soil spiked with a range of pyrene levels (1.07, 9.72, 88.4, 152, and 429 µg g⁻¹ dry soil) were measured in this study using both unaged (i.e., 0 days) and aged (i.e., 69, 150, and 222 days) soil samples. The results showed that the amount of pyrene accumulated by earthworms did not change greatly with aging time under different high-dose contamination levels, but changed significantly at lower concentrations. Moreover, aging (after 222 days) significantly decreased biological and chemical availability of pyrene. Furthermore, the relationship between earthworm bioaccumulation, hydroxypropyl-ß-cyclodextrin (HPCD), and organic solvent extraction was investigated in order to find a suitable and rapid method to predict pyrene bioavailability. Results showed that, at different levels of pyrene, the mean values of earthworm uptake and HPCD extractability were 10-40% and 10-65%, respectively. Correlation (r² = 0.985) and extraction results for pyrene suggested that mild HPCD extraction was a better method to predict bioavailability of pyrene in soil compared with organic solvent extraction.

QUAL2K model used in the water quality assessment of Qiantang River, China.

Qiantang River, a subwatershed of the Yangzi River, in China, is one of the main rivers in Zhejiang province. Because the Qiantang River is polluted as a result of urbanization and industrialization, its biochemical oxygen demand (BOD) concentration is increasing gradually, so that it is necessary to use versatile water quality models to assess the BOD concentration and make policies for pollution control. The QUAL2K model was applied to evaluate the spatial distribution of BOD in the Qiantang River. It was calibrated and validated using the data between 2000 and 2004 as a low-flow condition. Wastewater quantity, curtailed 25%, and a BOD level below 30.0 mg/L were simulated using this model. It was found that wastewater treatment is an effective method to reduce BOD content in the Qiantang River during a low-flow period. Also, the results suggest that BOD total maximum daily loads should be established to control pollution effectively. The QUAL2K model can provide the basic knowledge for water quality assessment in this area.

Source separation of household waste: a case study in China.

A pilot program concerning source separation of household waste was launched in Hangzhou, capital city of Zhejiang province, China. Detailed investigations on the composition and properties of household waste in the experimental communities revealed that high water content and high percentage of food waste are the main limiting factors in the recovery of recyclables, especially paper from household waste, and the main contributors to the high cost and low efficiency of waste disposal. On the basis of the investigation, a novel source separation method, according to which household waste was classified as food waste, dry waste and harmful waste, was proposed and performed in four selected communities. In addition, a corresponding household waste management system that involves all stakeholders, a recovery system and a mechanical dehydration system for food waste were constituted to promote source separation activity. Performances and the questionnaire survey results showed that the active support and investment of a real estate company and a community residential committee play important roles in enhancing public participation and awareness of the importance of waste source separation. In comparison with the conventional mixed collection and transportation system of household waste, the established source separation and management system is cost-effective. It could be extended to the entire city and used by other cities in China as a source of reference.

[Urban greenbelt eco-service value of Hangzhou City under effects of land use change: an evaluation with CITYgreen model].

Based on the Landset TM information of land use/cover change and greenbelt distribution in Hangzhou city in 1994 and 2004, and by using CITYgreen model, this paper estimated the eco-service value of urban greenbelt in the city under the effects of land use change and economic development. The results showed that in the 10 years from 1994 to 2004, the greenbelt area in the city decreased by 20. 4% , while its eco-service value increased by 168 million yuan. The annual increment of greenbelt eco-service value and GDP was 111.92% and 5. 32% , respectively. Suitable adjustment of land use pattern in the city harmonized the relationships between urban economic development and urban eco-function, and achieved higher eco-service efficiency of land utilization.

[Agricultural application of sludge dredged from landscape water bodies].

The feasibility and ecological effects of agricultural application of sludge dredged from the Grand Canal (Hangzhou Section) were studied. Applied too much dredged sludge to red soil and paddy soil affected the germination of alpine fescue [Fescuta ovina var. brachyphylla (Schult.) Piper] and colver (Trifolium repens. L) seeds, while there wasn't significantly affects in pot experiment. While the application rate was lower than 270 t.hm-2, the growth of pakchoi (Brassica chinensis L.) increased as application rate increasing. While the application rate was higher than 270 t.hm-2, the growth of pakchoi decreased. The flowers and grasses in garden were more suitable for the dredged sludge application, and there was significant increase of growth while the application rate was lower than 1080 t.hm-2. Contents of copper and zinc exceed hygiene standard, while the application rate was above 1350 t.hm-2. While the application rate was lower than 450 t.hm-2, the pollution of the groundwater had not been observed. The results showed that land application was an economical and feasible way for the disposal of sludge dredged from landscape water bodies, and horticultural application was more safe and economical than agricultural application.