TEMPORAL CHANGES IN THE YADKIN RIVER FLOW VERSUS SUSPENDED SEDIMENT CONCENTRATION RELATIONSHIP1

ABSTRACT: Dynamic linear models (DLM) and seasonal trend decomposition (STL) using local regression, or LOESS, were used to analyze the 50‐year time series of suspended sediment concentrations for the Yadkin River, measured at the U.S. Geological Survey station at Yadkin College, North Carolina. A DLM with constant trend, seasonality, and a log₁₀ streamflow regressor provided the best model to predict monthly mean log₁₀ suspended sediment concentrations, based on the forecast log likelihood. Using DLM, there was evidence (odds approximately 69:1) that the log₁₀ streamflow versus log₁₀ suspended sediment concentration relationship has changed, with an approximate 20 percent increase in the log₁₀ streamflow coefficient over the period 1981 to 1996. However, sediment concentrations in the Yadkin River have decreased during the decade of the 1990s, which has been accompanied by a concomitant increase in streamflow variability. Although STL has been shown to be a versatile trend analysis technique, DLM is shown to be more suitable for discovery and inference of structural changes (trends) in the model coefficient describing the relationship between flow and sediment concentration.     

基于可接受安全间距的单车道交通流模拟模型

交通流微观模拟是采用计算机对交通流进行描述及分析的方法。尤其对于复杂的交通流而言,微观模拟具有明显的优势,然而模拟的准确与否,关键在于模型的建立。笔者即是在研究我国单车道交通流特点的基础上,借鉴车道变换理论,基于驾驶员可接受的交通安全间距,分析安全变换车道的各间距之间的关系,阐述了有超车的单车道交通流模拟模型的建立方法     

Spatial correlation and influencing factors of industrial agglomeration and pollution discharges: a case study of 284 cities in China

Environmental Science and Pollution Research - Exploring the spatial correlation characteristics and influencing factors of industrial agglomeration and pollution discharge, which is of great...     

Full-scale blending treatment of fresh MSWI leachate with municipal wastewater in a wastewater treatment plant

Fresh leachate, generated in municipal solid waste incineration (MSWI) plants, contains various pollutants with extremely high strength organics, which usually requires expensive and complex treatment processes. This study investigated the feasibility of blending treatment of MSWI leachate with municipal wastewater. Fresh MSWI leachate was pretreated by coagulation–flocculation with FeCl₃ 2 g/L and CaO 25 g/L, plate-and-frame filter press, followed by ammonia stripping at pH above 12. After that, blending treatment was carried out in a full-scale municipal wastewater treatment plant (WWTP) for approximately 3 months. Different operational modes consisting of different pretreated leachate and methanol addition levels were tested, and their performances were evaluated. Results showed that throughout the experimental period, monitored parameters in the WWTP effluent, including COD (<60 mg/L), BOD₅ (<20 mg/L), ammonium (<8 mg/L), phosphorus (<1.5 mg/L) and heavy metals, generally complied with the Chinese sewage discharged standard. Under the experimental conditions, a certain amount of methanol was needed to fulfill TN removal. An estimation of the operation cost revealed that the expenditure of blending treatment was much lower than the total costs of respective treatment of MSWI leachate and municipal wastewater. The outcomes indicated that blending treatment could not only improve the treatability of the MSWI leachate, but also reduce the treatment cost of the two different wastewaters.     

Optimization of bio-drying of kitchen waste: inoculation,initial moisture content and bulking agents

Journal of Material Cycles and Waste Management - Bio-drying has been proved to be a promising method for treatment of MSW (municipal solid waste) and sewage sludge due to its high energy...     

夏、冬季降雨中溶解性有机质(DOM)光谱特征及来源辨析

利用紫外-可见光谱与三维荧光光谱,结合拉格朗日混合单粒子轨道模型及火点图,研究了重庆2013年夏、冬两季雨水DOM光谱特征,并对其来源进行解析.结果表明,雨水DOM与水体、土壤DOM具有类似性质光谱特征,证明降雨DOM也是陆地及水环境中DOM地化特征的重要贡献者.雨水DOM中DOC含量为0.88~12.80 mg·L-1,CDOM含量在3.17~21.11m-1之间,夏、冬两季降雨DOM差异明显(P0.05).与夏季相比,冬季降雨DOM分子量较小,芳香性程度较低,腐殖化程度也更低,输入主要以本地和短距离输送为主;而夏季DOM来源较分散.尽管吸收和荧光光谱可用于解析雨水DOM组成和来源,但在光谱特征的解析和来源识别上与其他来源DOM有所区别,传统"内、外源区分"并不适用于雨水DOM.     

Geochemistry of heavy metal-contaminated sediments from the Four River inlets of Dongting lake,China

Environmental Science and Pollution Research - The concentrations of major and trace elements in the sediments from the Four River inlets of Dongting Lake were analysed. The results show that the...     

Synthesis of efficient Y-Bi2WO6/G visible light photocatalysts with high stability for pollutant degradation

Environmental Science and Pollution Research - For effective photocatalytic pollutant degradation on bismuth tungstate (Bi2WO6), it is vital to enhance the photogenerated charge separation and the...     

Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.