再生水中消毒副产物——卤乙酸的测定方法研究

参照美国国家环保局(USEPA)推荐的饮用水卤乙酸类消毒副产物测定方法(Method 552.3),通过优化该方法的预处理条件和改变检测方法,提出了酸化萃取-衍生化-中和萃取-GC-MS测定再生水中卤乙酸含量的分析方法,并分析了北方某市再生水中4种卤乙酸类消毒副产物含量。结果表明,该方法适用于我国再生水水质,能够有效地消除再生水中共存污染物的干扰;其相对标准偏差(n=7)小于10%,方法的精密度较好;检出限与USEPA方法基本一致;样品加标回收率满足USEPA 6251B标准方法中(100±30)%要求;再生水中的卤乙酸比自来水高出几十倍,对环境和人类存在一定的潜在危害。     

PCB contamination in soils of the Pearl River Delta, South China: levels, sources, and potential risks

Polychlorinated biphenyls (PCBs) contamination in tropical and sub-tropical areas and the associated risks have attracted great concern. A total of 69 samples representing five distinct land types were collected to assess PCB concentrations in the Pearl River Delta (PRD), South China, including spatial distributions in soils of the area, the probable anthropogenic sources, and related potential risks. PCBs concentrations in soils of the PRD ranged from 0.3 to 202 ng?g^?1. More severe PCBs contamination was presented in the western part than in the eastern part of the PRD region. The PCBs were dominated by low-chlorinated biphenyls; however, the proportion of higher-chlorinated biphenyls was elevated with the influence of industrial activities. Principal component analysis indicated that PCBs contamination in soils of the PRD region was mainly associated with 1#PCBs, while 2#PCB and e-waste emission in South China also accounted for it partly, especially to the industrial activity severely impacted areas. Toxic equivalent (TEQ) of the dioxin-like PCBs in the soils indicated that higher risk of PCB contamination was presented in the Dongjiang River Valley (55 ng?TEQ?kg^?1, on average) than in the Xijiang River Valley, and were mostly contributed by the congener of PCB126.     

Plant community characteristics and their responses to environmental factors in the water level fluctuation zone of the three gorges reservoir in China

The annual water level regulating of the Three Gorges Reservoir prolonged the submerged duration (from 2 to 8 months) and resulted in the reversal of natural flood rhythms (winter submerged). These changes might alter plant community characteristics in the water level fluctuation zone (WLFZ). The aim of this study was to determine the plant community characteristics in the WLFZ and their responses to the environmental factors (i.e., annual hydrological regulation, topographic characteristics, soil physical properties and soil nutrients). The height, coverage, frequency and biomass of each plant species and the soil properties at each elevation zone (150, 155, 160, 165 and 170 m) were measured from March to September in 2010. Univariate two-factor analysis and redundancy analysis (RDA) were used to analyze the spatial and temporal variations of the community characteristics and identify the key environmental factors influencing vegetation. We found that 93.2 % of the species analysed were terrestrial vascular plants. Annual herbs made up the highest percentage of life forms at each altitude. The differences in the species number per square metre, the Shannon–Wiener diversity index and the biomass of vegetation demonstrated statistical significance with respect to sampling time but not elevation. The most dominant species at altitudes of 150, 155, 160, 165 and 170 m were Cynodon dactylon, Cyperus rotundus, Digitaria sanguinalis, Setaria viridis and Daucus carota, respectively. The concentrations of soil nutrients appeared to be the lowest at an altitude of 150 m, although the differences with respect to elevation were not significant. The results of the RDA indicated that the key factors that influenced the species composition of vegetation were elevation, slope, pH and the concentration of soil available phosphorus.     

Ecological risk of pesticide residues in the British Columbia environment: 1973–2012

An updated ecological risk assessment was conducted to re-evaluate and review the overall risk of pesticide residues to certain aquatic life. The focus was the impact on offsite non-target, freshwater organisms of pesticide operational sprays in British Columbia from 1973 until 2012. The values of risk quotients for pesticides of selected indicator organisms were determined to measure the effect. When compared with organophosphorus, carbamate, and other miscellaneous pesticides, this risk assessment analysis suggests that the historical use of persistent and highly toxic organochlorine pesticides posed, and continue to pose, a deleterious ecological risk. The risk is both short-term acute and long-term sub-acute, chronic toxicity to offsite, non-target aquatic invertebrates and juvenile salmonid fish. Data indicated that these organisms were, and remain, subjected to harmful effects of pesticide residues to varying degrees. Most vulnerable were, and also are, benthic organisms inhabiting bottom sediments. This substrate is the natural sink for persistent pesticide residues, predominantly organochlorine pesticides from historical use, as well as dioxins, furans, and polycyclic aromatic hydrocarbons from wood preservatives, and other sources. Environment Canada's main aquatic protection strategy was a 10 metre no-treatment buffer zone, augmented with an additional appropriate setback along shorelines of fishery and wildlife resource-sensitive water bodies. This study discusses why this guideline was necessary, useful and effective, but was only partially successful. The physical-chemical properties of pesticide residues, from either an individual compound or different compounds in combination, also influence the nature of biological impacts on non-target, aquatic organisms. Few studies have been conducted in British Columbia aquatic environments to investigate the significance of this aspect.     

Organophosphorus insecticide residues in farm ditches of the Lower Fraser Valley of British Columbia

Abstract

Farm ditches flowing into three important rivers in the Lower Fraser Valley of British Columbia, Canada, were sampled periodically at seven locations from July to December in 1991, to determine the occurrence and levels of seven organophosphorus (OP) insecticides. Based oh sales records for the year, the uses of OP insecticides in this area were as follows: malathion > diazinon > parathion > dimethoate > azinphos‐methyl > fensulfothion, but no sales of chlorfenvinphos. Residues of parathion, diazinon, fensulfothion, dimethoate and chlorfenvinphos were detected at levels ranging from 1 ‐ 7,785 >μg/kg in cropped soils collected from areas adjacent to the sites for sampling ditch water and sediments. Malathion and azinphos‐methyl were not detected in any of the substrates studied, demonstrating their rapid degradation in the environment. Diazinon and dimethoate were consistently found in ditch water at seven locations, with an average concentration of 0.07 μg/L and 0.27 μg/L, respectively. Fensulfothion and parathion, with an average concentration of 0.08 μg/L and 0.17 μg/L, respectively, were sporadically found in ditch water at two locations. In ditch sediments, diazinon was detected at three locations and fensulfothion at two. The average concentrations of these two insecticides were 16 μg/kg and 9 jug/kg, respectively. The potential impact on aquatic organisms of these OP insecticides in ditches is discussed.     

Risk assessment for human consumption of perfluorinated compound-contaminated freshwater and marine fish from Hong Kong and Xiamen

Perfluorinated compounds (PFCs) are man-made fluoro-surfactants that are identified as global pollutants and can pose health risks to humans and wildlife. Two aspects of risk assessment were conducted in this study, including exposure and response. Exposure was estimated by using the concentrations of PFCs in fish and applying standard exposure factors. Among different PFCs, PFOS, PFOA, PFNA, PFDA, PFUdA and PFTrDA were detected. Total concentrations of PFC in fish ranged from 0.27-8.4 ng g⁻¹ to 0.37-8.7 ng g⁻¹ respectively in Hong Kong and Xiamen. The calculated hazard ratio (HR) of PFOS for all fish was less than 1.0. However, the HR for mandarin fish in Hong Kong and bighead carp, grass carp and tilapia in Xiamen, had HR values of approximately 0.5, indicating that frequent consumption of these 4 more contaminated fish species might pose an unacceptable risk to human health. Our data support the notion that the released/disposed chemical pollutants into water systems make fish a source of environmental toxicants to humans. The risks and potential effects of PFCs to health of coastal population in the Pearl River Delta are of concern.     

Calcium invigorates the cadmium-stressed <Emphasis Type="Italic">Brassica napus</Emphasis> L. plants by strengthening their photosynthetic system

Introduction  

Cadmium (Cd) in plants interrupts numerous metabolic processes and reduces the water and nutrient uptake that cause chlorosis, growth retardation, and ultimately plant death. Response of Brassica napus L. to calcium (Ca) enrichment in growth medium for reducing Cd toxicity stress by strengthening the photosynthesis organelles and their functionality was explored in this study.     

Relationship between (210)Pb(ex) activity and sedimentary organic carbon in sediments of 3 Chinese lakes

This report demonstrates that organic matter was an important factor in lake sediment ²¹⁰Pb_ex dating. Sediment cores from lakes in central and western China with different-trophic levels were collected, and the ²¹⁰Pb_ex activity and total organic carbon (TOC) were measured. The Rock-Eval pyrolysis technique was used to deconvolute TOC into free hydrocarbons (S1), thermally less-stable macromolecular organic matter (S2a), kerogen (S2b), and residual carbon (RC). The results show significant correlations between TOC and ²¹⁰Pb_ex, particularly between S2a and ²¹⁰Pb_ex, in all the sediment cores. This indicated that the algal-derived organic component S2a may play the most important role in controlling the distribution of ²¹⁰Pb_ex. Scavenging by algal-derived organic matter may be the main mechanism. As chronology is the key to the understanding of pollution reconstruction and early diagenesis in sediments, more attention should be paid to the influence of organic matter on ²¹⁰Pb_ex.     

序批式生物膜反应器去除猪场厌氧消化液中的总磷

针对猪场废水的危害和难处理性分析了温度、氨氮和COD对序批式生物膜反应器(SBBR)处理猪场厌氧消化液的除磷效果的影响.实验结果表明,(1)一定温度范围内温度升高不利于SBBR对厌氧消化液的除磷作用;(2)随着进水厌氧消化液氨氮浓度的增加,SBBR对总磷的去除效率从刚开始93.5%降到38.1%,氨氮浓度的升高不利于总...     

桥门式起重机啃轨原因分析

从轨道缺陷、车轮缺陷等方面分析了桥式起重机啃轨的原因 ,提出了解决措施