Dechlorination and organohalide-respiring bacteria dynamics in sediment samples of the Yangtze Three Gorges Reservoir

Several groups of bacteria such as Dehalococcoides spp., Dehalobacter spp., Desulfomonile spp., Desulfuromonas spp., or Desulfitobacterium spp. are able to dehalogenate chlorinated pollutants such as chloroethenes, chlorobenzenes, or polychlorinated biphenyls under anaerobic conditions. In order to assess the dechlorination potential in Yangtze sediment samples, the presence and activity of the reductively dechlorinating bacteria were studied in anaerobic batch tests. Eighteen sediment samples were taken in the Three Gorges Reservoir catchment area of the Yangtze River, including the tributaries Jialing River, Daning River, and Xiangxi River. Polymerase chain reaction analysis indicated the presence of dechlorinating bacteria in most samples, with varying dechlorinating microbial community compositions at different sampling locations. Subsequently, anaerobic reductive dechlorination of tetrachloroethene (PCE) was tested after the addition of electron donors. Most cultures dechlorinated PCE completely to ethene via cis-dichloroethene (cis-DCE) or trans-dichloroethene. Dehalogenating activity corresponded to increasing numbers of Dehalobacter spp., Desulfomonile spp., Desulfitobacterium spp., or Dehalococcoides spp. If no bacteria of the genus Dehalococcoides spp. were present in the sediment, reductive dechlorination stopped at cis-DCE. Our results demonstrate the presence of viable dechlorinating bacteria in Yangtze samples, indicating their relevance for pollutant turnover.     

Understanding the Price Dynamics in the Jiangsu SO2 Emissions Trading Program in China: A Multiple Periods Analysis

Because emissions permits can be considered to be a pseudo-commodity, the permit price in the emissions trading markets has already attracted great interest from the economic literature. This research took the Jiangsu sulfur dioxide (SO₂) emissions trading program in China as a case study to examine the price dynamics over the next 10 years (2011–2020) based on Jiangsu’s new SO₂ emissions trading policy design. An adaptive agent-based simulation model was developed to estimate the price dynamics as well as the impact of energy price, policy design, and new environmental regulation on the permit price. The results showed that the equilibrium price of the Jiangsu SO₂ emissions trading market is approximately 4.20 CNY/kg, and the permit price will fluctuate around this price if the other conditions are not changed. If the coal price increases during 2011–2016, the permit price will decline to 2.79 CNY/kg by 2020 under China’s current coal–electricity price mechanism. In addition, the banking mechanism will smooth the price fluctuations and the average permit price will be generally higher when banking is not allowed. Finally, the stricter environmental regulation will reduce the market supply of permits and will raise the permit price. According to China’s potential new SO₂ discharge standard, the permit price will jump to 11 CNY/kg. The quantification of the permit price dynamics can help power plants to make decisions on emissions trading.     

异波折板水解酸化-A~2O一体化反应器实验研究

设计了异波折板水解酸化-A2O一体化反应器,进行生活污水处理的实验研究。10个月的实验结果表明,系统的最佳水力停留时间(HRT)为8 h时,最适COD进水浓度为240~600 mg/L,最佳混合液回流比(r)-污泥回流比(R)为250%~100%。控制反应器于以上运行参数下,25±2℃所对应的COD、TN和TP去除率分别为96.84%、67.55%和81.92%。当温度降至7℃时,其COD、TP和TN分别降至86.35%、50.25%和65.68%。基于实验分析结果,阐明了一体化反应器高效性的机理在于异波折板水解酸化段具有高效传质特性和A2O段具有复合式活性污泥-接触氧化好氧池的特点。     

Carbon disulfide at a Chinese viscose factory external and internal exposure assessment

This article presents the results of carbon disulfide exposure measurements in a Chinese viscose rayon factory. The objectives of the study were to identify the external exposure levels at a large factory and to investigate the 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations in the urine of the subjects who were exposed to carbon disulfide in the working place atmosphere. The metabolism of carbon disulfide in the exposed subjects was also studied in order to demonstrate the best points in time for the internal exposure sampling. The measurement of the amount of personal exposure to carbon disulfide in the air of the workplace was performed by GC-FPD; the presence of TTCA in the workers urine was analyzed by use of a modified HPLC method. The kinetics of TTCA excretion was studied by analyses at different time-points both during and after exposure to carbon disulfide in the subjects. A total of 155 personal samples were obtained. The carbon disulfide concentration in the staple viscose hall was 13.72 +/- 1.12 mg m-3 in terms of the geometric mean +/- geometric standard deviation, and was 20.05 +/- 1.33 mg m-3 in the filament spinning hall. The TTCA values in the subjects who worked in the staple spinning hall were 1.18 +/- 0.43 mg g-1 creatinine and 1.07 +/- 0.38 mg g-1 creatinine for subjects working in the filament spinning hall. The best time for TTCA sampling is at the end of the working shift, the TTCA excretion was stable for a period of 4-12 h after exposure of the subjects to the carbon disulfide. It might be that the Chinese have different anthropometric characteristics; a sampling bias may therefore appear among different races.     

Chemical- and effect-oriented exposomics: Three Gorges Reservoir (TGR)

Exposomic studies of the rapidly changing environment of the Three Gorges Reservoir (TGR) after its impounding is elaborated as a novel field of human and environmental research. Molecular exposomics is focused on the measure of all exposures to molecules and especially persistent organic pollutants-like compounds are of emerging interest due to their lifetime existence in the environment and humans. Theoretical considerations in general and particular for the TGR are deduced and presented using quantitative approaches for this research field. Since exposomics is strongly time-dependent, a theory is presented to link extension of exposure, time, and related effects. Similarity to the first law of thermodynamics is outlined. On top of this, the integrated use of biomarkers is presented employing chemical analysis for biomarkers of exposure and effects, biomarkers in vivo, in vitro approaches and the link between chemical mixtures, and the onset of disease and lethality. Besides real organisms, also virtual organisms are favored to act as well-defined sub-compartments such as fat of biota and with respect to time of exposure. Exposomics is the perspective of risk evaluation and chronic exposures in the running century. It needs novel theories, approaches, and integrated action between medical and environmental disciplines. The existing knowledge about molecular stressors has to be assembled and put into a context especially with respect not only to time resp. lifetime exposure of humans but also eco-toxicological findings by using highly conserved phylogenetic mechanisms to enable links between human and risks of environmental biota. The TGR is a good example not only to employ biomonitoring of real but also virtual organisms due to the lack of established ecotopes in this changing environment so far. Progress in understanding long-term risks requires a proper theory as well as novel tools such as virtual organisms. On top, multidisciplinary approaches and the utilization of existing knowledge about the exposure of the environment and humans have to be merged and directed into mutual concepts. Effect-oriented and chemical analysis must be designed time-oriented to determine lifetime exposures of mankind and nature. Perspectively, a first attempt about exposomic theory and concepts is proposed and has to be developed experimentally further enclosing virtual besides of real organisms and compartments. Environmental and human exposomics have to be considered as a unified global issue in order to effectively utilize their mutual existing knowledge most effectively. The TGR is a challenging model system aiming this objective.     

Survey of heavy metal pollution and assessment of agricultural soil in Yangzhong district, Jiangsu Province, China

We investigated concentrations of Hg, Cd, Pb, Zn, Cu, As, Ni, and Cr in samples of soil, cereal, and vegetables from Yangzhong district, China. Compared to subsoils, the sampled topsoils are enriched in Hg, Cd, Cu, Pb, Zn, and As. High levels of Cd and Hg are observed in most agricultural soils. Concentrations of Cr and Ni show little spatial variation, and high Cu, Pb, and Zn contents correspond well to areas of urban development. High As contents are primarily recorded at the two ends of the sampled alluvion. The contents of Cd, Hg, and total organic carbon (TOC) increase gradually to maximum values in the upper parts of soil profiles, while Cr and Ni occur in low concentrations within sampled profiles. As, Pb, Cu, and Zn show patterns of slight enrichment within the surface layer. Compared to data obtained in 1990, Cd and Hg show increased concentrations in 2005; this is attributed to the long-term use of agrochemicals. Cr and Ni contents remained steady over this interval because they are derived from the weathering of parent material and subsequent pedogenesis. The measured As, Cu, Pb, and Zn contents show slight increases over time due to atmospheric deposition of material sourced from urban anthropogenic activity. Low concentrations of heavy metals are recorded in vegetables and cereals because the subalkaline environment of the soil limits their mobility. Although the heavy metal concentrations measured in this study do not pose a serious health risk, they do affect the quality of agricultural products.     

Seasonal variation on size distribution and concentration of PAHs in Guangzhou city, China

Size distribution aerosol samples were collected at an urban location of Guangzhou in four seasons of 2003-2004 by a MOUDI (Micro-orifice Uniform Deposit Impactor). The particle loading (PM10: 80-397 microg m(-3)) was comparable with some other Asia cities; however, much higher than that of Western Europe and North America. Polycyclic aromatic hydrocarbons (PAHs) were measured by gas chromatography with mass selective detector (GC-MS). Seasonal effects on the size distribution of PAHs are presented. Bimode (accumulation and coarse mode) and unimode (accumulation mode) distributions were observed for low-molecule-weight and high-molecule-weight PAHs. A slight shift to larger particles was found for the accumulation mode in autumn and winter, compared with that of spring and summer. One explanation is that the longer aging process of PAHs in autumn and winter would result in volatilization from finer particles followed by condensation onto coarser particles. Another is there was mixing process of local emission with long-range transported aerosol in autumn and winter. The relative higher value of IcdP/(BghiP+IcdP) and lower value of BghiP/BeP in winter also give evidences to the mixing process. The level of PAHs concentration has been much elevated in recent years. This can be attributed to the fast growth of motor vehicle and energy consumption.     

Potentially toxic metal contamination of urban soils and roadside dust in Shanghai, China

A detailed investigation was conducted to understand the contamination characteristics of a selected set of potentially toxic metals in Shanghai. The amount of Pb, Zn, Cu, Cr, Cd and Ni were determined from 273 soil/dust samples collected within urban area. The results indicated that concentration of all metals except Ni in soils was significant, and metal pollution was even severer in roadside dust. A series of metal spatial distribution maps were created through geostatistical analysis, and the pollution hotspots tended to associate with city core area, major road junctions, and the regions close to industrial zones. In attempt of identifying the source of metals through geostatistical and multivariate statistical analyses, it was concluded as follows: Pb, Zn and Cu mainly originated from traffic contaminants; soil Ni was associated with natural concentration; Cd largely came from point-sourced industrial pollution; and Cr, Ni in dust were mainly related to atmospheric deposition.