Accumulation pattern of Dechlorane Plus and associated biological effects on rats after 90 d of exposure

Recent studies have indicated that Dechlorane Plus (DP) is widespread in the environments. However, different isomer-specific enrichment pattern of syn-DP and anti-DP was reported in biological samples from the field. In this study, Sprague–Dawley rats were consecutively exposed to commercial DP 25 by gavage for 90 d at different doses (0, 1, 10, and 100 mg kg^?1 d^?1) to investigate the accumulation pattern of syn-DP and anti-DP in liver, muscle, and serum of rats. The possible biological effects of DP on rats were also examined. Results showed that DP preferentially accumulated in the liver rather than in muscle at all exposure levels. No significant stereoselectivity of anti-DP or syn-DP in tissues was observed in the low DP exposure groups (0 and 1 mg kg^?1 d^?1) with f_anti values (defined as the concentration of the anti-DP divided by the sum of concentrations of anti- and syn-DP) ranging from 0.74 to 0.78. However, f_anti values reduced (f_anti ranged from 0.26 to 0.30) significantly in the high DP exposure groups (10 and 100 mg kg^?1 d^?1) and syn-DP was predominant in all tissues. Biochemical parameters in serum, the mRNA expression levels of certain enzymes and their activities in liver were detected. There was no observable-effect in histopathology and death during the experiment, although the mRNA expression levels of some genes in the low dosage group decreased significantly and enzyme activity of CYP 2B2 increased.     

Temporal trends of hydrocarbons in sediment cores from the Pearl River Estuary and the northern South China Sea

Concentrations and fluxes of unresolved complex mixture of hydrocarbons (UCM) and polycyclic aromatic hydrocarbons (PAHs) were analyzed for two ²¹⁰Pb dated sediment cores from the Pearl River Estuary (PRE) and the adjacent northern South China Sea (NSCS). Compound-specific stable carbon isotopic compositions of individual n-alkanes were also measured for identification of the hydrocarbon sources. The historical records of PAHs in the NSCS reflected the economic development in the Pearl River Delta during the 20th century. PAHs in the NSCS predominantly derive from combustion of coal and biomass, whereas PAHs in the PRE are a mixture of petrogenic and pyrogenic in origins. The isotopic profiles reveal that the petrogenic hydrocarbons in the PRE originate predominantly from local spillage/leakage of lube oil and crude oils. The accumulation rates of pyrogenic PAHs have significantly increased, whereas UCM accumulation has slightly declined in the NSCS in the recent three decades.     

Distribution and partition of polycyclic aromatic hydrocarbon in surface water of the Pearl River Estuary, South China

Water samples were collected in the Pearl River Estuary in July 2002 and April 2003. The particulate and dissolved phase polycyclic aromatic hydrocarbons (PAHs) were determined. Total PAH concentrations in water samples were higher in April of 2003 (C (p): 4.0-39.1 ng/L or 445.1-1,089.9 ng/g; C (w): 15.9-184.2 ng/L) than in July of 2002 (C (p): 2.6-26.6 ng/L or 297.7-1,336.6 ng/g; C (w): 12.9-28.3 ng/L). It was found that 5, 6-ring PAHs enrich in the inner estuary samples and so did 3-ring PAHs in the July samples. Compositional differences in the suspended particulate matter (SPM) might be responsible for this observation. The partition coefficient (K (p)) increased with the increasing of the particular organic carbon content of suspended particles as well as the salinity of water, decreased with the increase of the total suspended particles content of samples. A linear correlation between logK (OC) and logK (OW) was found in two sampling periods. The observed values of logK (OC) exceed their predicted values derived form linear free energy relationship between logK (oc) and logK (ow), which could be attributed to the nonlinear sorption of soot-like carbons in suspended particles.     

二(2-乙基己基)磷酸大块液膜中传输四价铈的研究

二(2-乙基己基)磷酸(DEHPA)一直成功的作为一种含有氯仿膜的大块液膜载体有效的传输Ce~(4+)。文章采用有氯仿膜的大块液膜方法进行Ce~(4+)的传输研究,结果表明:pH为2左右的料液中含有纯净的Ce~(4+)或者Ce~(4+)与一些阳离子二者的混合物,这些阳离子包括Ca~(2+),Mg~(2+),Na~+,K~+,Pb~(2+),Fe~(3+),Cu~(2+),以及UO~(2+)等,而0.1mol/L的盐酸为传输池中分散相的反萃取剂。大于99%的Ce~(4+)会在2h以内有选择的渗入液膜以内,而在相同时间内其他阳离子的传输量将少于3%。料液相中存在的Fe~(3+)和UO~(2+)的存在对铈离子的传输有极大的影响。Fe~(3+)可以有效地利用加入到料液中的硫氰化钾或柠檬酸加以掩蔽,但是UO~(2+)的共传输却只能利用加入到料液相中的碳酸盐或硫氰酸盐来加以减少。     

污水中易生物降解有机物的测定方法及研究进展

污水中的易生物降解有机物（SS）对生物脱氮除磷过程具有重要意义,也是活性污泥模型中的关键组分。介绍了污水中SS的测定方法,其中好氧呼吸计量法（包括连续OUR法和批式OUR法）和物料平衡法最为常用,而对比发现批式OUR法的测定结果最接近真实值。对文献数据统计表明,城市污水的SS浓度通常为20mg/L-40 mg/L,而工业废水中SS浓度受行业影响很大,SS/COD的波动范围为0.6%-44.0%。     

区域可持续发展评价工作的经常化问题

讨论了区域可持发展评价的经常化问题，提出了一张通用的指导性评价指标清单及其使用方法。经过实例模拟验算，认为基本可行，建议让区域可持续发展评价工作成为政府的定期行为 。     

Dynamic Modeling of the Ratio Volatile Fatty Acids/Bicarbonate Alkalinity in a UASB Reactor for Potato Processing Wastewater Treatment

In this work, dynamic mathematical model for the prediction of the operational parameter volatile fatty acids/bicarbonate alkalinity (VFA/ALK) in a UASB reactor was developed. The dynamic modeling technique was applied successfully to a two-year data record from an industrial wastewater treatment plant of a potato processing industry. The technique used included regression analysis by residuals. Seventeen parameters were examined including the following: wastewater's flow rate, reactor's temperature and pH, total and soluble influent COD, wastewater's temperature and pH, total and soluble effluent COD, volatile fatty acids, alkalinity, biogas production rate and each parameter with a time lag of up to 10 days. Finally, after all parameters and all time lag trials the best fitted model was developed. The model's adequacy was checked by χ² test for a data record of the same UASB reactor but at a different time period and proved to be satisfactory. Additionally, the model's ability to predict and to control the plant's operation via VFA/ALK was examined. Through this model, in contrary to steady state models, various aspects of the process can be enlighten, such as the fact that the hydrolysis of starch requires at least a resident time of seven days.     

Proximate composition of household waste and applicability of waste management technologies by source separation in Hanoi,Vietnam

The organic fraction of municipal solid wastes in Southeast Asia, which has a high moisture content, accounts for a large proportion of total waste. Local governments need to pay adequate attention to the composition of wastes to determine alternative waste management technologies. This study proposed the use of a triangle diagram to describe changes in proximate composition and rates of successful source separation of municipal solid waste and to identify technical challenges about alternative waste management technologies such as incineration, composting, and refuse-derived fuel production based on physical and proximate composition analysis of household waste sampled in Hanoi, Vietnam, as a case study. The analysis indicated the effectiveness of different types of source separation as well as different levels of successful achievement of source separation as an adjustment mechanism for the proximate composition of waste. Proper categorization of wastes for source separation is necessary for the appropriate use of alternative waste management technologies. The results showed that, at a source separation rate of just greater than 0.52 in a three-way separation scheme, the waste separated as combustible waste would be suitable for incineration with energy recovery. Based on well-designed schemes of source separation, alternative waste management technologies can be applied.     

Environmental regulation,foreign direct investment,and export sophistication of China: an empirical study based on dynamic system GMM and threshold model

Environmental Science and Pollution Research - The mechanism of how environmental regulations (ERs) affect export sophistication (ES) is complex, and for many years, it has been a hot topic for...     

Antibiotic and antiparasitic residues in surface water of urban rivers in the Red River Delta (Hanoi,Vietnam): concentrations,profiles, source estimation,and risk assessment

Environmental Science and Pollution Research - Antibiotic residues and antimicrobial resistance in surface water are issues of global concern, especially in developing countries. In this study, the...