Tropical surface water quality studies: Implications for the aquatic fate of N-methyl carbamate pesticides

Water quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21–1.51 ppm), nitrates (2.28–4.89 ppm) and phosphates (0.01–0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8–10 ppm), ammonia (0.02–0.22 ppm) and phenols (0.19–0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08–7.70) with a temperature of 17.8–21.2°C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18°C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.     

Cd,Pb, and Cu in water and sediments and their bioaccumulation in freshwater fish of some lakes in Hanoi,Vietnam

The seasonal variations of Cd, Pb, and Cu in the water, sediments, and freshwater fish (Hypophthalmichthys molitrix, Cirrhinus molitorella, and Oreochromis mossambicus) of four lakes in Hanoi, Vietnam, were investigated. Samples for analysis were taken four times from April 2010 to March 2011. The levels in water were lower than the Vietnamese standards, except for Pb, but they were all much higher than the Canadian standards for protection of aquatic life; in the sediments, they were higher than world average levels. Bioaccumulation of the three metals in fish was site-dependent and species-dependent, but correlations of their levels in fish to those in water and sediments were weak. Levels of Pb in fish exceeded those of the UK and the WHO standards, and the recommended values of Vietnam for human consumption. Overall, the results show that the lakes are polluted with these metals, and consumption of high quantities of fish from them may be problematic. The outcome of this research helps to establish background data for future monitoring.     

Effect of a seasonal diffuse pollution migration on natural organic matter behavior in a stratified dam reservoir

This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter (NOM) in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter (DOM) including refractory dissolved organic carbon (RDOC) and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.     

环保督政约谈机制分析:以安阳市为例

环保督政约谈制度是环保新常态下的一项制度尝试。本文以安阳市作为案例点,从约谈的法律依据、整改措施等方面对环保督政约谈制度进行了研究。研究发现环保督政约谈制度有一定的法律基础,在国外和国内许多行业也有类似的实践,实施该制度以来已取得一定成效,但也存在部分措施行政色彩较重、长效机制缺乏、环境问题责任界定不清等问题。文章提出了要明确政府部门职责,提高环保执法能力并建立“尽责免责”机制,要创新约谈模式,试行“党政同责”和“部门问责”,强化整改措施落实,加大信息公开并加强监督和跟踪评估,逐步建立环保“阳光”约谈的长效机制等建议。     

Prediction of effluent concentration in a wastewater treatment plant using machine learning models

Of growing amount of food waste, the integrated food waste and waste water treatment was regarded as one of the efficient modeling method. However, the load of food waste to the conventional waste treatment process might lead to the high concentration of total nitrogen (T-N) impact on the effluent water quality. The objective of this study is to establish two machine learning models—artificial neural networks (ANNs) and support vector machines (SVMs), in order to predict 1-day interval T-N concentration of effluent from a wastewater treatment plant in Ulsan, Korea. Daily water quality data and meteorological data were used and the performance of both models was evaluated in terms of the coefficient of determination (R²), Nash–Sutcliff efficiency (NSE), relative efficiency criteria (d_rel). Additionally, Latin-Hypercube one-factor-at-a-time (LH-OAT) and a pattern search algorithm were applied to sensitivity analysis and model parameter optimization, respectively. Results showed that both models could be effectively applied to the 1-day interval prediction of T-N concentration of effluent. SVM model showed a higher prediction accuracy in the training stage and similar result in the validation stage. However, the sensitivity analysis demonstrated that the ANN model was a superior model for 1-day interval T-N concentration prediction in terms of the cause-and-effect relationship between T-N concentration and modeling input values to integrated food waste and waste water treatment. This study suggested the efficient and robust nonlinear time-series modeling method for an early prediction of the water quality of integrated food waste and waste water treatment process.     

Fostering coastal resilience to climate change vulnerability in Bangladesh,Brazil, Cameroon and Uruguay: a cross-country comparison

This paper describes a comparative study of four different cases on vulnerability, hazards and adaptive capacity to climate threats in coastal areas and communities in four developing countries: Bangladesh, Brazil, Cameroon and Uruguay. Coastal areas are vulnerable to sea-level rise (SLR), storm surges and flooding due to their (i) exposure, (ii) concentration of settlements, many of which occupied by less advantaged groups and (iii) the concentration of assets and services seen in these areas. The objective of the paper is twofold: (i) to evaluate current evidence of coastal vulnerability and adaptive capacity and (ii) to compare adaptation strategies being implemented in a sample of developing countries, focusing on successful ones. The followed approach for the case evaluation is based on (i) documenting observed threats and damages, (ii) using indicators of physical and socioeconomic vulnerability and adaptive capacity status and (iii) selecting examples of successful responses. Major conclusions based on cross-case comparison are (a) the studied countries show different vulnerability, adaptive capacity and implementation of responses, (b) innovative community-based (CBA) and ecosystem-based adaptation (EbA) and (c) early warning systems are key approaches and tools to foster climate resilience. A recommendation to foster the resilience of coastal communities and services is that efforts in innovative adaptation strategies to sea-level rise should be intensified and integrated with climate risk management within the national adaption plans (NAPAs) in order to reduce the impacts of hazards.     

Anaerobic degradation kinetics of reactive dye with different carbon sources

This study aims to investigate the anaerobic degradation kinetics of reactive dye, C.I. Reactive Red 141 (Evercion Red H-E7B) by partially granulated anaerobic mixed culture using three carbon sources, namely modified starch (MS), polyvinyl alcohol (PVA) and acrylic size (AS) during batch incubation. There is a first-order kinetics reaction in the decolorization processes using MS and PVA as carbon sources, while a zero-order kinetics relationship describes the decolorization process for the AS carbon source. The k values and color removal rate of decolorization with MS carbon source was higher than those of PVA and AS carbon sources. This is because the MS carbon source was well degraded in comparison to AS and PVA, respectively This study also found dye reduction could be enhanced through the addition of MS as a carbon source. The decolorization rates increased with decrease in dye concentrations of RR 141. In contrast, the decolorization rates increased with increase in COD concentration.     

Desorption characteristics of kaolin clay contaminated with zinc from electrokinetic soil processing

A number of bench scale laboratory column tests were carried out using a newly designed and developed electrokinetic cell to investigate the fundamental behavior of zinc-spiked kaolin clay subjected to an electric field. Laboratory investigations focused on (i) zinc migration by the combined effects of electromigration and electro-osmosis and (ii) the electrically induced desorption characteristics of zinc-contaminated kaolin that occurred during processing. The correlations of the applied voltage gradient, electro-osmotic flow rate, and the development of a pH gradient were examined and evaluated. The results showed that the removal efficiency was high during the early stage of processing due to rapid desorption by electrokinetic effects in the cathode region. However, the majority of zinc migrating from the anode was precipitated due to the high pH environment in the cathode region.     

呼伦池主要鱼体中总汞含量的调查

本文报道了采用冷原子吸收法,对呼伦池中九种九十尾鱼体中汞含量测定调查结果。总汞含量范围4.69～171.00μg/kg,平均值为42.12μg/kg。九种鱼比较,鲶鱼含汞量最高(88.72μg/kg),其次是鲤鱼(76.35μg/kg),蒙古红鲌和银鲫居第三。白鲢等五种鱼体内汞含量较低,除红鳍鲌、银鲫和蒙古贝氏餐条外,鲤鱼、蒙古红鲌、瓦氏雅罗鱼体内累积的汞量随年龄、体重和体长的增长而升高。