Heavy metal sources and associated risk in response to agricultural intensification in the estuarine sediments of Chaohu Lake Valley, East China

Water quality degradation is often a severe consequence of rapid economic expansion in developing countries. Methods to assess spatial-temporal patterns and trends in water quality are essential for guiding adaptive management efforts aimed at water quality remediation. Temporal and spatial patterns of surface water quality were investigated for 54 monitoring sites in the Wen-Rui Tang River watershed of eastern China to identify such patterns in water quality occurring across a rural-suburban-urban interface. Twenty physical and chemical water quality parameters were analyzed in surface waters collected once every 4-8 weeks from 2000 to 2010. Temporal and spatial variations among water quality parameters were assessed between seasons (wet/dry) and among major land use zones (urban/suburban/rural). Factor analysis was used to identify parameters that were important in assessing seasonal and spatial variations in water quality. Results revealed that parameters related to organic pollutants (dissolved oxygen (DO), chemical oxygen demand (manganese) (COD Mn ), and 5-day biochemical oxygen demand (BOD 5 )), nutrients (ammonia nitrogen (NH 4 + -N), total nitrogen (TN), total phosphorus (TP)), and salt concentration (electrical conductivity (EC)) were the most important parameters contributing to water quality variation. Collectively, they explained 70.9 % of the total variance. A trend study using the seasonal Kendall test revealed reductions in COD Mn , BOD 5 , NH 4 + -N, petrol, V-phen, and EC concentrations over the 11-year study period. Cluster analysis was employed to evaluate variation among 14 sampling sites representative of dominant land use categories and indicated three, three, and four clusters based on organic, nutrient, and salt water quality characteristics, respectively. Factors that are typically responsible for water quality degradation (including population, topography, and land use) showed no strong correlation with water quality trends implying considerable point source inputs in the watershed. The results of this study help inform ongoing water quality remediation efforts by documenting trends in water quality across various land use zones.

Section: Discussionmentioning

confidence: 99%

Evaluation of spatial-temporal variations and trends in surface water quality across a rural-suburban-urban interface

Mei

Liao

Zhu

et al. 2014

“…A 0.1-g (dry weight) aliquot of each sediment sample was digested in 8 mL of a 9:3:4 (by volume) mixture of concentrated HCl, HNO 3 , and HF using a MARSXpress instrument (CEM, Matthews, NC, USA). A drop of HClO 4 was added to the digestion tube, then the acid was heated to 150°C for at least 2 h (Tang et al 2010). The extract was then diluted to 50 mL with ultrapure water, then passed through a 0.45-μm membrane filter and stored at 4°C until it was analyzed.…”

Section: Heavy Metal Analysismentioning

confidence: 99%

Heavy metals in surface sediments of the shallow lakes in eastern China: their relations with environmental factors and anthropogenic activities

Zhang

Jin

et al. 2016

Self Cite

The aquatic environment is affected by heavy metal pollution. This study was conducted to test the hypothesis that environmental factors and anthropogenic activities influence the distributions and the risks posed by heavy metals in surface sediments in shallow lakes in eastern China, which is an area affected by rapid urbanization, industrialization, and population growth. Total Cd, Cr, Cu, Ni, Pb, Se, and Zn concentrations in sediment samples were determined using inductively coupled plasma optical emission spectrometry. The I geo showed that sediments in the lakes were moderately polluted with Cr,Cu,Pb,and Zn,and the EF method showed that Cd and Se were significantly enriched in lakes. The heavy metals were found to pose moderate risks in most of the lakes, except for Gaoyou Lake, Honghu Lake, Poyang Lake, and Weishan Lake. The RI method indicated that very high risks were posed in Dongting Lake and Poyang Lake. Cd was found to pose much higher levels of risk than the other metals. Significant correlations were found between the heavy metal concentrations and the total carbon, nitrogen, phosphorus, and sulfur concentrations. The gross domestic product represented anthropogenic activities well. The gross domestic product of an area and the gross domestic products of primary and secondary industries in an area all had significant relationships with the concentrations of Cu and Pb, indicating that anthropogenic activities have different impacts on pollution with different heavy metals. The gross domestic product index was found to be a driving force behind the pollution of lakes with heavy metals.

“…It is a typical large, shallow, subtropical lake that covers an area of 780 km 2 and has a mean water depth of 2.7 m. Because of the agricultural intensification in recent decades, deterioration of the aquatic environment in the lake Chaohu Valley has become a serious environmental problem (Tang et al 2010).…”

Section: Study Areamentioning

confidence: 99%

Distribution of arsenic between the particulate and aqueous phases in surface water from three freshwater lakes in China

Yang

Geng

Wei

et al. 2015

Total arsenic (As) in suspended particulate matter (SPM) of lacustrine ecosystems has been extensively documented, but knowledge on the distribution of As between the particle and aqueous phases in freshwater lakes remains largely unknown. The present study employed a rapid method to determine the total and dissolved As and As in SPM at sites covering the entire areas of three large shallow lakes in China, e.g., Taihu, Chaohu, and Dianchi, to obtain a Brepresentativem ean value of the As concentration in various phases. The average concentrations of total and dissolved As were below 6.0 and 3.3 μg/L, respectively. Arsenic in SPM was much higher than that in waters, as ranging from 24.7 to 516 μg/g. Lake Taihu exhibited extensive seasonal variation both in total and dissolved As, while little difference was observed in SPM concentration, with an average value of 54.2 and 49.3 mg/L in winter and summer, respectively. Among the algae in the three lakes, Cyanophyta dominated in both cell abundance and biomass. Algae mass occupied significant parts of SPM, especially in Dianchi; the proportions of algae in the SPM fractions were measured as 10.4 and 7.1 % in Taihu in winter and summer, 4.5 % in Chaohu, and 53.3 % in Dianchi, both in summer season. The total As in SPM had a significant positive relationship with total As in water and a high distribution coefficient (Kd) between SPM and dissolved fraction of As at all three lakes. The high proportions of Algae, especially Cyanophyta in the composition of SPM in the three large shallow lakes, might play an important role in affecting the As distribution between the aqueous and particulate phases in aquatic ecosystem.