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He L.,Zhejiang Agriculture And forestry University | Fan S.,Zhejiang Agriculture And forestry University | Muller K.,The New Zealand Institute for Plant and Food Research Ltd | Hu G.,Zhejiang Agriculture And forestry University | And 7 more authors.
Chemosphere | Year: 2016

A pot experiment was conducted to evaluate the effect of biochars on the bioavailability of di-(2-ethylhexyl) phthalate (DEHP) in two soils using Brassica chinensis L. as an indicator plant. The residual concentrations of DEHP tended to be higher in the biochar-amended soils than in the control soils. They were lower (p<0.05) in the high organic carbon content soil (HOC; 2.2%C) than in the low organic carbon content soil (LOC; 0.35%C). The DEHP concentrations in plant shoots grown in the HOC soils were lower than those in the LOC soils (p<0.05). Compared to the control, the biochar addition decreased the DEHP concentrations in shoots grown in the LOC soils; whereas there was no significant difference in the HOC soils. Our results showed that soil OC content as well as biochar properties are the key factors influencing the bioavailability of DEHP in soils. © 2015 Elsevier Ltd. Source

Yang X.,Zhejiang University | Liu J.,Zhejiang University | McGrouther K.,Scion Research | Huang H.,Bijie Yancao Company of Guizhou Province | And 8 more authors.
Environmental Science and Pollution Research | Year: 2016

Biochar is a carbon-rich solid material derived from the pyrolysis of agricultural and forest residual biomass. Previous studies have shown that biochar is suitable as an adsorbent for soil contaminants such as heavy metals and consequently reduces their bioavailability. However, the long-term effect of different biochars on metal extractability or soil health has not been assessed. Therefore, a 1-year incubation experiment was carried out to investigate the effect of biochar produced from bamboo and rice straw (at temperatures ≥500 °C) on the heavy metal (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) extractability and enzyme activity (urease, catalase, and acid phosphatase) in a contaminated sandy loam paddy soil. Three rates (0, 1, and 5 %) and two mesh sizes (<0.25 and <1 mm) of biochar applications were investigated. After incubation, the physicochemical properties, extractable heavy metals, available phosphorus, and enzyme activity of soil samples were analyzed. The results demonstrated that rice straw biochar significantly (P < 0.05) increased the pH, electrical conductivity, and cation exchange capacity of the soil, especially at the 5 % application rate. Both bamboo and rice straw biochar significantly (P < 0.05) decreased the concentration of CaCl2-extractable heavy metals as biochar application rate increased. The heavy metal extractability was significantly (P < 0.01) correlated with pH, water-soluble organic carbon, and available phosphorus in soil. The 5 % application rate of fine rice straw biochar resulted in the greatest reductions of extractable Cu and Zn, 97.3 and 62.2 %, respectively. Both bamboo and rice straw biochar were more effective at decreasing extractable Cu and Pb than removing extractable Cd and Zn from the soil. Urease activity increased by 143 and 107 % after the addition of 5 % coarse and fine rice straw biochars, respectively. Both bamboo and rice straw biochars significantly (P < 0.05) increased catalase activity but had no significant impact on acid phosphatase activity. In conclusion, the rice straw biochar had greater potential as an amendment for reducing the bioavailability of heavy metals in soil than that of the bamboo biochar. The impact of biochar treatment on heavy metal extractability and enzyme activity varied with the biochar type, application rate, and particle size. © 2015, Springer-Verlag Berlin Heidelberg. Source

Zhang X.,Zhejiang Agriculture And forestry University | Wang H.,Zhejiang Agriculture And forestry University | He L.,Zhejiang Agriculture And forestry University | Lu K.,Zhejiang Agriculture And forestry University | And 6 more authors.
Environmental Science and Pollution Research | Year: 2013

Soil contamination with heavy metals and organic pollutants has increasingly become a serious global environmental issue in recent years. Considerable efforts have been made to remediate contaminated soils. Biochar has a large surface area, and high capacity to adsorb heavy metals and organic pollutants. Biochar can potentially be used to reduce the bioavailability and leachability of heavy metals and organic pollutants in soils through adsorption and other physicochemical reactions. Biochar is typically an alkaline material which can increase soil pH and contribute to stabilization of heavy metals. Application of biochar for remediation of contaminated soils may provide a new solution to the soil pollution problem. This paper provides an overview on the impact of biochar on the environmental fate and mobility of heavy metals and organic pollutants in contaminated soils and its implication for remediation of contaminated soils. Further research directions are identified to ensure a safe and sustainable use of biochar as a soil amendment for remediation of contaminated soils. © 2013 Springer-Verlag Berlin Heidelberg. Source

Lu K.,Zhejiang Agriculture And forestry University | Yang X.,Zhejiang Agriculture And forestry University | Shen J.,Zhejiang Agriculture And forestry University | Robinson B.,Lincoln University at Christchurch | And 5 more authors.
Agriculture, Ecosystems and Environment | Year: 2014

Soil contamination with heavy metals has become a global concern because of its adverse effects on ecosystem health and food security. Soil amendments including biochar can reduce the bioavailability of heavy metals in contaminated soils and reduce their risk of entering the food chain. A pot experiment was conducted to investigate the effects of biochars derived from bamboo and rice straw on bioavailability and plant growth in a sandy loam paddy soil naturally co-contaminated with Cd, Cu, Pb and Zn. The soil was moderately acidic (pH = 5.7) and low in organic carbon content (8.7 g kg-1). Bamboo and rice straw biochars, pyrolyzed at temperatures ≥ 500 °C and with two mesh sizes (< 0.25 mm and < 1 mm), were applied at three rates (0, 1% and 5%, w/w). A metal-tolerant plant, Sedum plumbizincicola X. H. Guo et S. B. Zhou sp. nov. was used in the plant growth experiment to examine the bioavailability of these metals. The addition of biochars to soil significantly (p < 0.05) increased the above-ground biomass of S. plumbizincicola. By the end of the experiment, soils amended with biochar had pH values significantly (p < 0.05) higher, this effect being more accentuated at the high biochar dose and small particle size. The solubility of Cd, Cu, Pb, and Zn as measured by Toxicity Characteristic Leaching Procedure (TCLP) was significantly lower (p < 0.05) in the biochar-amended soils than in the control soil. This was paralleled by significant reductions in Cd, Cu, Pb and Zn accumulated in the above-plant biomass of amended soils. Rice straw biochar reduced the concentration of Cu and Pb in the shoots by 46 and 71%, while bamboo biochar reduced concentration of Cd in the shoot by 49%. Finer biochar was more effective on reducing the concentrations of Zn in shoot than the coarse ones, while particle size had no effect on the concentrations of Cd, Cu and Pb in the shoot of S. plumbizincicola. In conclusion, the influence of biochar on heavy metal bioavailability varied not only with the feedstock and application rate of biochars, but also with the metal species. Therefore, biochar should be carefully designed to maximize the reduction of the bioavailability of a given heavy metal in soil. © 2014 Elsevier B.V. All rights reserved. Source

He L.,Zhejiang University | Gielen G.,Scion Research | Bolan N.S.,University of South Australia | Zhang X.,Zhejiang University | And 3 more authors.
Agronomy for Sustainable Development | Year: 2015

Phthalic acid esters have been used as plasticizers in numerous products and classified as endocrine-disrupting compounds. As China is one of the largest consumers of phthalic acid esters, some human activities may lead to the accumulation of phthalic acid esters in soil and result in contamination. Therefore, it is necessary for us to understand the current contamination status and to identify appropriate remediation technologies. Here, we reviewed the potential sources, distribution, and contamination status of phthalic acid esters in soil. We then described the ecological effect and human risk of phthalic acid esters and finally provided technologies to remediate phthalic acid esters. We found that (1) the application of plastic agricultural films, municipal biosolids, agricultural chemicals, and wastewater irrigation have been identified as the main sources for phthalic acid ester contamination in agricultural soil; (2) the distribution of phthalic acid esters in soils is determined by factors such as anthropogenic behaviors, soil type, properties of phthalic acid esters, seasonal variation, etc.; (3) the concentrations of phthalic acid esters in soil in most regions of China are exceeding the recommended values of soil cleanup guidelines used by the US Environmental Protection Agency (US EPA), causing phthalic acid ester in soils to contaminate vegetables; (4) phthalic acid esters are toxic to soil microbes and enzymes; and (5) phthalic acid ester-contaminated soil can be remedied by degradation, phytoremediation, and adsorption. © 2014, INRA and Springer-Verlag France. Source

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