Contaminant removal from low-concentration polluted river water by the bio-rack wetlands

The bio-rack is a new approach for treating low-concentration polluted river water in wetland systems. A comparative study of the efficiency of contaminant removal between four plant species in bio-rack wetlands and between a bio-rack system and control system was conducted on a small-scale (500 mm length × 400 mm width × 400 mm height) to evaluate the decontamination effects of four different wetland plants. There was generally a significant difference in the removal of total nitrogen (TN), ammonia nitrogen (NH₃-N) and total phosphorus (TP), but no significant difference in the removal of permanganate index (COD_Mn) between the bio-rack wetland and control system. Bio-rack wetland planted with Thalia dealbata had higher nutrient removal rates than wetlands planted with other species. Plant fine-root (root diameter ≤ 3 mm) biomass rather than total plant biomass was related to nutrient removal efficiency. The study suggested that the nutrient removal rates are influenced by plant species, and high fine-root biomass is an important factor in selecting highly effective wetland plants for a bio-rack system. According to the mass balance, the TN and TP removal were in the range of 61.03--73.27 g/m² and 4.14--5.20 g/m² in four bio-rack wetlands during the whole operational period. The N and P removal by plant uptake constituted 34.9%--43.81% of the mass N removal and 62.05%--74.81% of the mass P removal. The study showed that the nitrification/denitrification process and plant uptake process are major removal pathways for TN, while plant uptake is an effective removal pathway for TP.     

Green finance and corporate environmental responsibility: evidence from heavily polluting listed enterprises in China

Green finance is not just a global trend, but it has become an important channel for industrialized countries to achieve sustainable growth. However, few studies have discussed the environmental governance effects of green finance from the micro-firm level. Based on the data of Chinese A-share listed firms in heavily polluting industries, we, combining with property rights and environmental regulation, empirically research the influence of green finance on corporate environmental responsibility (CER) performance. Results indicate that green finance has a significant negative effect on the environmental responsibility of heavily polluting firms. The result remains after a series of robustness tests. In addition, property rights and environmental regulation play a moderating role in the above relationship. The negative impact of green finance on CER is stronger in private firms and firms in areas with low environmental regulation intensity. Moreover, we observe that green finance decreases the CER performance of heavily polluting firms by increasing financing constraints, reducing environmental investment, and diminishing technological innovation. This study identifies the external factors that influence CER and also provides implications and theoretical support for the government to improve the setting and the implementation of green finance policy in the future.

     

Cation exchange resin supported nanoscale zero-valent iron for removal of phosphorus in rainwater runoff

Self-made cation exchange resin supported nanoscale zero-valent iron （R-nZVI） was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial concentration of 0.72 mg. L-1 phosphorus when the dosage of R-nZVl is 8 g per liter rainwater, while only 26% of phosphorus was removed when using cation exchange resin without supported nanoscale zero-valent iron under the same condition. The adsorption capacity of R-nZVI increased up to 185 times of that of the cation exchange resin at a saturated equilibrium phosphorous concentration of 0.42 mg. L-1. Various techniques were implemented to characterize the R-nZVI and explore the mechanism of its removal of phosphate. Scanning electron microscopy （SEM） indicated that new crystal had been formed on the surface of R-nZVI. The result from inductive coupled plasma （ICP） indicated that 2.1% of nZVI was loaded on the support material. The specific surface area was increased after the load of nanoscale zero-valent iron （nZVI）, according to the measurement of BET-N2 method. The result of specific surface area analysis also proved that phosphorus was removed mainly through chemical adsorption process. X-ray photoelectron spectroscopy （XPS） analysis showed that the new product obtained from chemical reaction between phosphate and iron was ferrous phosphate.     

北江河水中抗生素抗性基因污染初步研究（Preliminary Studies on the Pollution Levels of Antibiotic Resistance Genes in the Water of Beijiang River, South China）

环境中细菌的耐药性,尤其是对抗生素的耐药性已成为影响生态环境的重要因素.论文采用抗生素抗性平板法调查了北江河水中四环素、红霉素及磺胺类这3类抗生素耐药性细菌的存在,采用定性PCR及荧光定量PCR方法分别研究了该水域sul1和sul2这2种磺胺类抗生素抗性基因(ARGs)的存在和含量水平.结果表明,所采集北江水域的9个样品中有5个对四环素有耐药性,7个对红霉素有耐药性,8个对磺胺二甲嘧啶有耐药性;定性PCR实验并经基因测序结果证实,5个样品含有sul1,4个样品含有sul2.进一步的PCR定量分析结果显示,7个样品中均检出sul1和sul2磺胺抗性基因,它们与内对照基因16S-rRNA表达量比值分别在10-2.56~10-0.52及10-3.25~10-1.24范围内,该结果显著高于美国科罗拉多州北部河流的研究结果.此外,数据分析也发现,sul1和sul2磺胺抗性基因的含量水平与该区域水中磺胺含量分布具有一定的相关性,表明外源性抗生素对河流的污染是诱导抗性基因的重要因素.     

Atmospheric gaseous organic acids in winter in a rural site of the North China Plain

Organic acids are important contributors to the acidity of atmospheric precipitation,but their existence in the Chinese atmosphere is largely unclear.In this study,twelve atmospheric gaseous organic acids,including C₁-C₉ alkanoic acids,methacrylic acid,pyruvic acid,and benzoic acid,were observed in the suburb of Wangdu,Hebei Province,a typical rural site in the northern China plain from 16^th December,2018 to 22^nd January,2019,using a Vocus@Proton-Trans...     

Effect of nitrobenzene on the performance and bacterial community in an expanded granular sludge bed reactor treating high-sulfate organic wastewater

Less than 50 mg/L nitrobenzene brought little effect on anaerobic sulfate reduction. Kinetics of sulfate reduction under different nitrobenzene contents was studied. Increased nitrobenzene contents greatly changed the bacterial community structure. Genus Desulfovibrio played the key role in anaerobic sulfate reduction process. Nitrobenzene (NB) is frequently found in wastewaters containing sulfate and may affect biological sulfate reduction process, but information is limited on the responses of sulfate reduction efficiency and microbial community to the increased NB contents. In this study, a laboratory-scale expanded granular sludge bed reactor was operated continuously to treat high-sulfate organic wastewater with increased NB contents. Results successfully demonstrated that the presence of more than 50 mg/L NB depressed sulfate reduction and such inhibition was partly reversible. Bath experiments showed that the maximum specific desulfuration activity (SDA) decreased from 135.80 mg SO₄^2?/gVSS/d to 30.78 mg SO₄^2?/gVSS/d when the NB contents increased from none to 400 mg/L. High-throughput sequencing showed that NB also greatly affected bacterial community structure. Bacteroidetes dominated in the bioreactor. The abundance of Proteobacteria increased with NB addition while Firmicutes presented an opposite trend. Proteobacteria gradually replaced Firmicutes for the dominance in response to the increase of influent NB concentrations. The genus Desulfovibrio was the dominant sulfate-reducing bacteria (SRB) with absence or presence of NB, but was inhibited under high content of NB. The results provided better understanding for the biological sulfate reduction under NB stress.     

我国腾冲大气PAHs的可能来源分析

2005年10月22日至2006年10月21日,在云南腾冲一典型背景点进行了每周一次的大气采样,以监测季风期东南亚地区生物质燃烧导致的多环芳烃(PAHs)的输入状况.结果表明,监测期内总PAHs含量为43.1~156ng/m3 (平均值为87.9ng/m3).其中气相PAHs均值为85.8ng/m3,无明显的季节变化;颗粒相PAHs均值为2.35ng/m3,在春季出现显著高值,可能与东南亚生物质燃烧释放的PAHs在南亚季风作用下向腾冲的跨境迁移有关.颗粒相PAHs以毒害性较大的高环PAHs化合物为主,其在偏远地区生态系统中的累积可能带来一定的生态风险.     

生态环境损害责任确立的理论基础研究——以马克思主义生态文明观为视角

中共中央办公厅和国务院办公厅印发的《生态环境损害赔偿制度改革试点方案》已经明确提出了生态环境损害的赔偿问题,对生态环境本身造成损害需要承担责任将成为中国法治时代又一个崭新的命题,对生态环境造成损害担责因何而生、又因何而立?生态环境损害责任确立的理论根据到底是什么?笔者认为只有明确生态环境损害责任确立的理论基础,才能促进生态损害赔偿制度的有效构建与救济机制的健康运行,才能为"美丽中国"建设提供法治保障。本文以马克思主义生态文明观为研究视角,探讨了生态文明观作为中国生态环境损害责任确立的理论基础之科学性与合理性。本文研究发现,马克思主义生态文明观不仅扫清了环境损害责任确立的思想和认识障碍,而且回应了个别学者对环境损害责任成立的质疑,为环境损害责任的确立奠定了思想和理论基础;不仅如此,生态文明观还为环境损害责任的实施提供了政治、经济、文化、技术和法治保障,是生态文明观孕育了环境损害责任。本文进一步分析了生态文明观之所以能够孕育环境损害责任制度的原因,是因为生态文明观与环境损害责任有诸多内在的共同性:生态文明观与环境损害责任之间同根同源,都起源于生态环境危机的时代背景,直接目的就是为了实现环境保护,共同的手段就是环境法治,最深层次的共同价值追求是实现人与自然的和谐共生。中国未来生态环境损害责任制度的建立与运行,应当自觉坚持以马克思主义生态文明观为指导,自觉将马克思主义生态文明观作为思想指南和理论渊源。     

苏丹红Ⅰ对小鼠卵巢的损伤作用及对Caspase-3和Ki-67表达的影响

苏丹红是一种人工合成偶氮染料,可引起肝脏及泌尿系统等多个脏器的肿瘤,但苏丹红对生殖系统的毒性研究较少.本研究以昆明小鼠为受试对象,探讨苏丹红Ⅰ对小鼠卵巢组织Caspase-3和Ki-67表达的影响.将24只昆明小鼠随机分为:对照组、低剂量(60 mg· kg-1)、中剂量(120 mg·kg-1)、高剂量(240 mg· kg-1)4组,6只/组.胃灌4周,4周末处死.HE染色观察各组卵巢组织病理变化,免疫组化法检测卵巢组织Caspase-3和Ki-67表达,Real time PCR检测卵巢组织Caspase-3和Ki-67 mRNA表达,Western blotting检测卵巢组织中Ki-67及Caspase-3蛋白表达.与对照组比较,实验组卵巢中Caspase-3阳性细胞率显著升高(Jp＜O.05),而Ki-67阳性细胞率显著降低(P＜0.05),Real time PCR及Western blotting结果与免疫组化法结果一致.本实验发现苏丹红染毒后颗粒细胞的Caspase-3表达增加,且Caspase-3表达呈剂量依赖性,但Ki-67表达受到抑制.