Yanhua Zhuang

Spatial distributions and temporal variations of atmospheric aerosols and the affecting factors: a case study for a region in central China

Using Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol data, temporal variations and the spatial distribution of aerosol optical depth (AOD or τ) over the Hubei Province in China were investigated from 2003 to 2008. self-organizing maps (SOMs) and linear models were further used to analyse the relationships between AODs and elevation, normalized difference vegetation index (NDVI) and population density. The results were as follows: high AOD values were observed in south-central areas with lower elevations, lower NDVI and larger population densities, whereas low AOD values were observed in the western, northeastern and southeastern areas. The highest AOD values were observed in spring; summer was characterized by lower AOD values, but also the largest ratio of fine particles; in autumn, the coverage of AOD was only smaller than spring with most being fine particles; in winter, coarse particles were dominant when AOD values were the lowest. The AOD monthly average rose substantially in the winter–spring season and dropped sharply in the spring–winter season. Based on these data, both SOMs and linear models show that AOD distribution is influenced by the complex interactions that occur among various elements. The annual AODs are negatively related to ln(elevation) and NDVI and positively related to ln(population density). The ln(elevation) factor affects aerosol distribution more than do the other two factors. Compared to fine-particle aerosols, the selected three factors have a greater impact on the coarse particles.

Worldwide performance and trends in nonpoint source pollution modeling research from 1994 to 2013: A review based on bibliometrics

Water quality deterioration as a consequence of nonpoint source (NPS) pollution or diffuse pollution has been documented around the world (Davis and Koop 2006; Ma et al. 2011; Novotny 1999; Smith 2003). This deterioration not only damages the social and ecological functions of water bodies as water supply, fisheries, ecosystem maintenance, and recreation (Pretty et al. 2003), but also largely raises water treatment and policy response costs (Novotny 1999; Pretty et al. 2003). Understanding and evaluating the processes of pollution generation, transport, and transformation are continuous challenges for scientists and engineers. Modeling as a way to simplify the complex natural processes has been widely used in NPS pollution research (Zhuang et al. 2012). There are various NPS pollution models available now, which were summarized and compared in different previous studies (Alexander et al. 2002; Borah and Bera 2003; Shen et al. 2012). These reviews of available models are meaningful, though they hardly provide a direct overview of worldwide research efforts and the general trends in NPS pollution modeling. Since researchers have conducted research in this field for several decades, a comprehensive and quantitative review of past efforts, including influencing researchers and their performance, participating regions and their activity, and general…

Identification of critical source areas for nonpoint source pollution in the Danjiangkou Reservoir Basin, China

ABSTRACT Zhuang Y, Zhang L, Du Y, Yang W, Wang L, Cai X. 2016. Identification of critical source areas for nonpoint source pollution in the Danjiangkou Reservoir Basin, China. Lake Reserve Manage. 32:341–352. Danjiangkou Reservoir is an important water source for the middle route of the South-to-North Water Diversion Project in China. Water quality is crucial for this project, and the identification of critical source areas (CSAs) plays a significant role in nonpoint source (NPS) pollution control. The load–area curve based on the Export Empirical Model was used to quantitatively classify CSAs of NPS pollution in the Danjiangkou Reservoir Basin as CSAs, sub-CSAs, and non-CSAs. About 70% of loads were from 30% of the basin. In CSAs, 45.4% of total nitrogen (TN) loads and 48.0% of total phosphorus (TP) loads were from 14.5% and 13.3% of the basin, respectively; in sub-CSAs, 19.7% of TN loads and 18.3% of TP loads were from 14.5% and 13.3% of the basin, respectively. CSAs of both TN and TP loads were mainly from areas near the reservoir, which are subject to severe soil erosion and large runoff discharge. In the Danjiangkou Reservoir Basin, we recommend a CSAs→sub-CSAs→non-CSAs hierarchical control in the NPS pollution management plan specifying that sloping farmland in Xichuan and Yunxian counties should be preferentially treated. The load–area curve offers a new way of identifying CSAs of NPS pollution and helps to establish effective control measures for NPS pollution.

Removal of phosphate in aqueous solutions by the aluminum salt slag derived from the scrap aluminum melting process

Aluminum salt slag, a kind of industrial by-product derived from the scrap aluminum melting process, was used to remove phosphate (P) from aqueous solutions in this research. The morphology and microstructure of the sample was characterized by Brunauer–Emmett– Teller (BET) analysis, X-ray photo-electron spectroscopy, scanning electron microscopy, and X-ray diffraction. According to the results, aluminum salt slag exhibited a surface area of 16.73 m 2 /g and a rough surface with many slit-shaped pores, and its main constituents were determined to be aluminum compounds and salt-flux mixture. The experimental kinetic data were well fitted using both the pseudo-second-order model and Elovich model, which revealed its nature of chemisorption and heterogeneous composites. Furthermore, the isotherm studies showed that it followed Freundlich model better than the Langmuir model, the maximal adsorption capacities calculated by Langmuir model were 2.312–3.467 mg/g. The thermodynamics study demonstrated that the adsorption process was endothermic. Additionally, it was found that a pH of 8.0 was most unfavorable to P removal and ligand exchange may be one of the main adsorption mechanisms. With the advantages of huge production, low costs, and desirable treatment efficiency, the aluminum salt slag is proposed to be another possible adsorbent for P removal from wastewater.

Influencing factor analysis of phosphorus loads from non-point source: a case study in central China.

The influence factor analysis for non-point source (NPS) pollution is very important to taking effective water pollution control measures. In this study, the self-organizing map (SOM) and linear model analysis were used to analyze the relationships between total phosphorus (TP) loads and influencing factors, both qualitatively and quantitatively. The land-use type, topography, and vegetation coverage were the main factors influencing the export of TP loads in Tangxun watershed. Slope and normalized difference vegetation index (NDVI) were chosen as characteristic indices of topography and vegetation coverage, respectively. For the whole watershed, the high TP loads were mainly distributed in areas with high slope and low vegetation coverage for a specific land-use type. For different land types, the slope significantly influenced the export of TP loads in waste/bare land and forest/green land while NDVI influenced the export of TP loads in forest/green land and farmland. In terms of multi-factor analysis, the comprehensive influence of slope and NDVI on TP loads showed as waste/bare land > forest/green land > farmland > rural/urban construction land.

Start-up performance of a novel constructed riparian wetland for removing phosphorus from agricultural runoff

The overloading agricultural phosphorus inputs play significant roles in accelerating eutrophication of receiving waters. For the propose of phosphorus removal from agricultural runoff, a field-scale free surface flow constructed riparian wetland system, with cost-effective and easily maintainable design, was constructed for receiving runoff from a small agricultural watershed on the northeastern lakeside rural areas of Liangzi Lake, China. During the start-up period, the system potentially provided a buffering capacity in irrigative and rainy periods. Wetland vegetations grew relatively well during the observed period (1 August–30 October 2012). Furthermore, the growth of vegetations has assisted in transforming the constructed riparian wetland structure to fit well with the surrounding landscape. The reductions in average concentrations of PO4-P and total phosphorus (TP) during the start-up period were approximately 75.6% and 46.5%, respectively. Moreover, the influences of environmental conditions on PO4-P and TP removal and retention in the constructed riparian wetland system were also analyzed. The results indicated that water temperature, conductivity, dissolved oxygen, and pH were important factors controlling phosphorus redistribution in the studied system. Generally, the constructed riparian wetland system preformed satisfactory during the start-up period, and it might be a suitable wastewater treatment tool for farms in poor rural areas.