No abstract

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.

Highlights• Biochar's effect on pak choi growth in Cd-DEHP co-contaminated soils was tested.• 2% pig biochar addition increased the yield of pak choi.• Pig biochar improved nutrient phytoavailabilities more than wood biochar.• Tested biochars enhanced soil urease, sucrase and catalase activities.• Biochars had prominent influence on pak choi growth in low organic carbon soil.

We investigated effects of low Mg and moderately raised NaCl, as occurs in plantations irrigated with tertiary municipal effluent in New Zealand, on growth, Mg nutrition and photosynthetic activity of Pinus radiata D. Don seedlings grown in nutrient solutions with a Perlite medium. Seedlings were grown with either sufficient (0.35 mM; H[Mg]) or limited (0.033 mM; L[Mg]) Mg supply, without NaCl or with NaCl addition (8.7 mM; +[NaCl]). After 30 weeks, seedlings grown at L[Mg] displayed severe Mg deficiency symptoms, and had significantly less biomass than those at H[Mg]. While NaCl addition had an adverse effect on seedling growth at H[Mg], it increased growth at L[Mg]. The +[NaCl] treatment greatly increased the Mg uptake rates, which were associated with increased stomatal conductance and increased root to shoot ratio. Magnesium deficiency reduced the rates of light-saturated photosynthesis and stomatal conductance, but not the quantum efficiency of photosystem II, which was reduced mainly by the +[NaCl] treatment, especially at H[Mg]. Our study clearly indicated that NaCl addition could counteract the impact of low Mg supply by enhancing Mg uptake from the rooting medium.