Levels, distributions, and sources of legacy and novel per- and perfluoroalkyl substances (PFAS) in the topsoil of Tianjin, China

Soil is a major sink for per- and perfluoroalkyl substances (PFAS), wherein PFAS may be transferred through the food chain to predators at upper trophic levels, which poses a threat to human health. Herein, the concentrations and distributions of legacy and novel PFAS in topsoil samples from different functional areas in Tianjin were comprehensively investigated. Seventeen PFAS congeners were identified, with concentrations ranging from 0.21 ng/g to 5.35 ng/g, with a mean concentration of 1.25 ng/g. The main PFAS in the topsoil was perfluorooctanoic acid (PFOA). 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA; <MDL–1.95 ng/g, mean 0.11 ng/g), as an emerging substitute for perfluorooctane sulfonate (PFOS), was also detected in the topsoil. It showed slightly higher concentrations than PFOS (<MDL–1.62 ng/g, mean 0.10 ng/g), indicating it has gradually replaced legacy PFOS in this area. Based on the positive-definite matrix factor (PMF) receptor model, the major PFAS sources was dominated by textile treatment, metal electroplating plants, and some potential precursors of PFAS with longer chains (>C8) were the major sources (43.4%), followed by food packaging as well as coating materials (25.5%). In addition, Spearman correlation analysis and the structural equation model showed that population density significantly impacted the PFAS distribution in the topsoil of Tianjin.     

The risks of sulfur addition on cadmium accumulation in paddy rice under different water-management conditions

Recently, the application of sulfur (S) has been recommended to control the accumulation of cadmium (Cd) in rice in contaminated paddy soil. However, the effects of exogenous S on Cd transfer in paddy rice systems under different water-management practices have not been systematically investigated. Pot experiments were performed to monitor the composition of soil pore water and the Cd accumulation in iron plaque and rice tissue were compared under different S (0 and 200 mg/kg Na₂SO₄) and water (continuous and discontinuous flooding) treatments. Sulfur application significantly increased Cd concentrations in soil pore water under discontinuous flooding conditions, but slightly reduced them under continuous flooding. Moreover, the oxidation/reduction potential (Eh) was the most critical factor that affected the Cd levels. When the Eh exceeded −42.5 mV, S became the second critical factor, and excessive S application promoted Cd dissolution. In addition, S addition elevated the Cd levels in iron plaque and reduced the Cd transfer from the iron plaque to rice roots. In rice, S addition inhibited Cd transfer from the rice roots to the straw; thus, more Cd was stored in the rice roots. Nevertheless, additional S application increased the Cd content in the rice grains by 72% under discontinuous flooding, although this effect was mitigated by continued flooding. Under simulated practical water management conditions, S addition increased the risk of Cd contamination in rice, suggesting that S application should be reconsidered as a paddy fertilization strategy.     

Biochar affects methylmercury production and bioaccumulation in paddy soils: Insights from soil-derived dissolved organic matter

Biochar has been used increasingly as a soil additive to control mercury (Hg) pollution in paddy rice fields. As the most active component of soil organic matter, soil dissolved organic matter (DOM) plays a vital role in the environmental fate of contaminants. However, there are very few studies to determine the impact of biochar on the Hg cycle in rice paddies using insights from DOM. This study used original and modified biochar to investigate their effect on DOM dynamics and their potential impact on methylmercury (MeHg) production and bioaccumulation in rice plants. Porewater DOM was collected to analyze the variations in soil-derived DOM in paddy soils. The results showed that the addition of biochar, whether in original or modified form, significantly reduced the bioaccumulation of MeHg in rice plants, especially in hulls and grains (p<0.05). However, MeHg production in soils was only inhibited by the modified biochar. Biochar addition induced a significant increase in DOM's aromaticity and molecular weight (p<0.05), which decreased Hg bioavailability. Furthermore, enhanced microbial activity was also observed in DOM (p<0.05), further increasing MeHg production in the soil. Thus, the effect of biochar on the fate of Hg cycle involves competition between the two different roles of DOM. This study identified a specific mechanism by which biochar affects Hg behavior in rice paddy soil and contributes to understanding the more general influence of biochar in agriculture and contaminant remediation.     

电石法聚氯乙烯行业履约的成本效益分析

构建汞物质平衡模型以识别高汞触媒及低汞触媒电石法聚氯乙烯(CCPVC)企业中汞的产生、转化和排放过程.进一步针对典型企业开展成本效益分析,比较通过低汞触媒替代来履行《关于汞的水俣公约》要求的各种方案.结果表明,案例企业将在履约的情况下,使废气和废水汞排放量分别减少25%和85.7%~98.9%,净效益增加50.7%~55.4%.案例企业最有利的选择将是在厂内回收废触媒并改进汞减排设施,但含汞固体废物的环境风险不可忽视.原因是《关于汞的水俣公约》侧重于CCPVC行业的汞输入而非汞排放.此外,目前的汞环境税率低于最优税率,无法为CCPVC企业提供足够的激励以控制汞排放.因此,为了提高《关于汞的水俣公约》的政策效力,有必要推动我国CCPVC行业汞物质平衡的构建,加强对含汞固体废物堆存的监管力度,提高汞排放的环境税率,并将所含的环境风险物质量作为固体废物的计税依据.     

Hydroxyl radical intensified Cu2O NPs/H2O2 process in ceramic membrane reactor for degradation on DMAc wastewater from polymeric membrane manufacturer

• Cu₂O NPs/H₂O₂ Fenton process was intensified by membrane dispersion. • DMAc removal was enhanced to 98% for initial DMAc of 14000 mg/L. • Analyzed time-resolved degradation pathway of DMAc under ·OH attack. High-concentration industrial wastewater containing N,N-dimethylacetamide (DMAc) from polymeric membrane manufacturer was degraded in Cu₂O NPs/H₂O₂ Fenton process. In the membrane-assisted Fenton process DMAc removal rate was up to 98% with 120 min which was increased by 23% over the batch reactor. It was found that ·OH quench time was extended by 20 min and the maximum ·OH productivity was notably 88.7% higher at 40 min. The degradation reaction rate constant was enhanced by 2.2 times with membrane dispersion (k = 0.0349 min⁻¹). DMAc initial concentration (C₀) and H₂O₂ flux (J_p) had major influence on mass transfer and kinetics, meanwhile, membrane pore size (r_p) and length (L_m) also affected the reaction rate. The intensified radical yield, fast mass transfer and nanoparticles high activity all contributed to improve pollutant degradation efficiency. Time-resolved DMAc degradation pathway was analyzed as hydroxylation, demethylation and oxidation leading to the final products of CO₂, H₂O and NO₃⁻ (rather than NH₃ from biodegradation). Continuous process was operated in the dual-membrane configuration with in situ reaction and separation. After five cycling tests, DMAc removal was all above 95% for the initial [DMAc]₀ = 14,000 mg/L in wastewater and stability of the catalyst and the membrane maintained well.     

不同生境产脂肪酶菌株的筛选及多样性

为发掘不同特性脂肪酶微生物资源,采用纯培养方法从青海高寒草地、雅安山区、成都平原分离得到产脂肪酶菌株54株.通过对菌株的DNA进行ERIC-PCR指纹图谱分析,按聚类树划分为5个操作分类单元.16S rDNA序列测定和聚类分析显示,分离菌株分布于芽孢杆菌属(Bacillus)、克雷伯氏菌属(Klebsiella)、假单胞菌属(Pseudomonas)、葡萄球菌属(Staphylococcus)、肠杆菌属(Enterobacter).多样性分析表明,与青海高寒草地、雅安山区相比,成都平原产脂肪酶菌株遗传多样性更为丰富.在54株菌中都出现了300 bp和1 300 bp两个特异且稳定出现的条带,这两个特异条带可能是产脂肪酶菌株的SCAR标记条带.     

Endocrine-disrupting chemicals in the Pearl River Delta and coastal environment: sources,transfer, and implications

A study was conducted to investigate the occurrence and behavior of six endocrine-disrupting chemicals (EDCs) in sewage, river water, and seawater from the Pearl River Delta (PRD). The six EDCs under study were 4-nonylphenol (NP), bisphenol A (BPA), 17α-ethynylestradiol (EE2), estrone (E2), 17β-estradiol (E2), and estriol (E3). These EDCs, predominated by BPA, were found in high levels in the influents and the effluents of sewage treatment plants in the area. The relatively high concentrations (0.23–625 ng/L) of the EDCs detected in the receiving river water suggested that the untreated sewage discharge was a major contributor. The EDCs detected in eight outlets of the Pear River and the Pear River Estuary were in the ranges of 1.2–234 and 0.2–178 ng/L, respectively. The estrogen equivalents in the aquatic environments under study ranged from 0.08 to 4.5 ng/L, with E1 and EE2 being the two predominant contributors. As the fluxes of the EDCs from the PRD region to the nearby ocean are over 500 tons each year, the results of this study point to the potential that Pearl River is a significant source of the EDCs to the local environment there.     

The development of WEEE management and effects of the fund policy for subsidizing WEEE treating in China

The consumption of electrical and electronic equipment is surging, so is the generation of waste electrical and electronic equipment (WEEE). Due to the large quantity, high potential risk and valuable capacity of WEEE, many countries are taking measures to regulate the management of WEEE. The environmental pollution and human health-harming problems caused by irregular treatment of WEEE in China make the government pay more and more attention to its management. This paper reviews the development of WEEE management in China, introduces the new policy which is established for WEEE recycling and especially analyzes the effectiveness of the policy, including huge recovery, formation of new recycling system, strict supervision to related enterprises, and the stimulation to public awareness. Based on the current achievement, some recommendations are given to optimize the WEEE management in China.