Jihong Jing

A regional scale investigation on factors controlling the groundwater chemistry of various aquifers in a rapidly urbanized area: A case study of the Pearl River Delta

A growing population accompanied by urbanization has increased groundwater resource demands in the Pearl River Delta (PRD) area, southern China, and a comprehensive understanding of the groundwater chemistry in the PRD is necessary. The aims of this study were to investigate the groundwater chemistry in various aquifers in the PRD on a regional scale and to discuss the factors that control the groundwater chemistries of different types of aquifers. In addition, the effect of the expansion of construction land on the groundwater chemistry was also taken into consideration in this study. Nearly 400 groundwater samples were collected and fourteen chemical parameters were investigated. The results show that natural factors, such as seawater intrusions, are mainly responsible for the higher concentrations of total dissolved solids, Na+, Mg2+, K+, and Cl-, in granular aquifers than those in fissured and karst aquifers. Similarly, higher concentrations of NH4+, Fe and Mn in granular aquifers than those in the other two types of aquifers are mainly ascribed to natural reduction. In contrast, human activities, such as the continuous irrigation of river water, upon granular aquifer are mainly responsible for the higher concentrations of Ca2+ and HCO3- in granular aquifers than those in other two types of aquifers. Urbanization and industrialization are the main driving forces for the frequently occurrences of NO3 and SO4 water types, respectively. Moreover, the number of water types in the PRD increased to 89 after the decades of urbanization. Factors that control groundwater chemistries in various aquifers were extracted. A four-factor model controlled the groundwater chemistry of granular aquifers, while two three-factor models controlled the groundwater chemistries of fissured and karst aquifers, respectively. The results of this study show that the expansion of construction land is a powerful driving force for the change of groundwater chemistry in the PRD.

Response of Groundwater to Climate Change under Extreme Climate Conditions in North China Plain

The North China Plain (NCP) is one of the water shortage areas of China. Lack of water resources restricted the economic and social development of North China area and resulted in deterioration of ecosystem and natural environment. Influenced by the climate change and human activities, the water circulation of NCP was largely changed and the crisis of water resources was aggravated. Therefore, it is important to study the features of the extreme climate and the response mechanism of groundwater to climate change. We analyzed the trend of climate change and extreme climate features in the past 60 years based on the monitoring data of meteorological stations. And then the response characteristics of groundwater to climate change were discussed. The average temperature of NCP was in an obviously upward trend. The overall precipitation variation was in a downward trend. The climate change in this area showed a warming-drying trend. The intensity of extreme precipitation displayed a trend of declining and then increasing from north to south as well as declining from eastern coastal plain to the piedmont plain. Grey correlation degree analysis indicated that groundwater depth had a close relationship with precipitation and human activities in NCP. The response of groundwater level to precipitation differed from the piedmont alluvial-pluvial plain to the coastal plain. The response was more obvious in the coastal plain than the piedmont alluvial-pluvial plain and the middle plain. The precipitation influenced the groundwater depth both directly and indirectly. Under the condition of extreme precipitation, the impact would aggravate, in the forms of rapid or lag raise of groundwater levels.

Distribution and Mobility of Heavy Metals in Soil of Sewage Irrigation Area in Pearl River Delta, China

The research reveals the mobility and distribution of heavy metals (Cd, Cu, Zn, Mn, Ni, and Cr) in soil of sewage irrigation area in Pearl River Delta. Samples were collected from topsoil (0-10cm) and subsoil (30-40cm), and the total concentration and available concentration of heavy metals were extracted by HNO3–HF–HClO4 and DTPA respectively. The mean total concentrations for all of the heavy metals in topsoil are higher than that in subsoil in study area. Cd has the best mobility in soil of study area due to soil has lower retention for Cd than for other metals, while Ni has the poorest mobility in soil of study area. The total concentrations of Zn, Cu and Cd decrease with the depth of soil profile, while the total concentrations of Cr and Ni have little change with the depth of soil profile, only the total concentration of Mn has a little decrease at first and then increased rapidly with the depth of soil profile.

Heavy Metal Contamination and Potential Ecological Risk Assessment of Sediments in Yangzonghai Lake

The contents and characteristics of ten heavy metals in surface sediments from Yangzonghai Lake in Yunnan, China were analyzed. Ecological risk index presented by Håkanson to assess the potential ecological risk of Yangzonghai Lake was utilized. The results showed that the average concentrations of titanium(Ti), manganese(Mn), zinc(Zn), vanadium(V), chromium(Cr), copper(Cu), nickel(Ni), cobalt(Co), lead(Pb) and arsenic(As) in surface sediments of Yangzonghai Lake were up to 9413.1, 617.9, 149.2, 189.6, 145.8, 97.6, 55.1, 27.4, 40.3 and 31.4mg/kg, respectively, which are higher than their natural background values. Pearson’s correlation analysis indicated that Zn, Cr, Pb and As were highly correlated, and the similar distributions in sediment indicated that they might originate from activities. Ti, Mn, V, Cu, Ni, and Co were also well correlated, and the distributions indicated that they were mainly from natural factors. The evaluation of pollution index revealed a clear accumulation of the 10 heavy metals, all reaching the level of moderate pollution. As, Cu and Cr were the most important environmental contaminants in Yangzonghai Lake. As a whole, heavy metals reached the level of low ecological risks, and in some parts, they reached the moderate level. Heavy metals in Yangzonghai Lake in the descending order of their ecological risks were As, Cu, Co, Ni, Pb, Cr, V, Zn, Mn and Ti. As was more prominent than other heavy metals in terms of the ecological risk and thus the most important factor of potential ecological risk in surface sediment of Yangzonghai Lake.

Natural Background Levels of Fe and Mn in Groundwater of Pearl River Delta

As scientific references of evaluation on the groundwater contamination, natural background levels about chemical indexes TFe and Mn of shallow groundwater in Pearl River Delta was derived with SPSS statistical software, and its spatial distribution regularities and the controlling factor were discussed. The results show that the regularity in Pearl River Delta is primarily controlled by topography, redox environment, property of the cover, and groundwater flow conditions.

A Regional Scale Investigation on Groundwater Arsenic in Different Types of Aquifers in the Pearl River Delta, China

Nearly 400 groundwater samples were collected from different types of aquifers in the Pearl River Delta (PRD), and the concentrations of groundwater arsenic (As) and other 22 hydrochemical parameters in different types of aquifers were then investigated. Results showed that groundwater As concentration was up to hundreds g/L in granular aquifers, while those in fissured aquifers and karst aquifers were only up to dozens and several g/L, respectively. Correspondingly, about 9.4% and 2.3% samples with high concentrations (>0.01 mg/L) of As were in granular and fissured aquifers, respectively, but no samples with high concentration of As were in karst aquifers. The source and mobilization of groundwater As in granular aquifers are likely controlled by the following mechanism: organic matter in marine strata was mineralized and provided electrons for electron acceptors, resulting in the release of and and the reduction of Fe/Mn and , and was accompanied with the mobilization of As from sediments into groundwater. By contrast, both natural processes including the competitive adsorption between As anions and / / and anthropogenic processes including industrialization were responsible for high concentrations of groundwater As in fissured aquifers.

Study on Application of Two-stage Bio-contact Oxidation Technology in Municipal Wastewater Treatment in Alpine Region

Following the introduction of characteristic of wastewater and correlated project in the Alpine Region, the problems were pointed out which should be noticed in wastewater treatment process selection in this specific area. Some suggestions about key design parameters were proposed, and the Two-stage Bio-contact Oxidation Technology was been selected and applied in wastewater treatment plant in north suburb of Dongsheng District, Erdos City. Through project application, it was indicated that when average value of COD, BOD5 and SS was 483.2mg/L, 244.4mg/L and 258.4mg/L respectively during 10 days at about 12 ° in influent wastewater, average value in effluent water reached up to 57.1mg/L, 23.8mg/L and 26.5mg/L and removal rate of each contaminant was up to 88.2%, 90.3% and 89.7% respectively. It gained preferable results and this successful project also provided references for other similar wastewater treatment plant for future.

Characteristic and Speciation of Beryllium in Shallow Groundwater in the Pearl River Delta

The Distribution of shallow groundwater containing beryllium were summarized and the major factors influencing beryllium enrichment were discussed in this paper, based on chemical data of Be, aluminum and pH from more than 900 groundwater samples in the Pearl River Delta. The results show that Be concentration ranges from less than 0.02µg•L-1 to 40.3µg•L-1, with the majority less than 0.05µg•L-1 and the mean Be content of 0.66µg•L-1. The samples of Be content exceeding the upper limit for drinking water in China were scatteredly found in Guangzhou, Shenzhen, Dongguan, Foshan and Huizhou, with the over proof rate of 2.24%. The distribution of Be contamination in groundwater is characterized by local punctate type. The pH and Al are the major factors influencing distribution of beryllium in groundwater. Acidic and high Al content in groundwater and soil provide favorable conditions for migration of Be. Rock weathering and natural soil formation is one of the origins of Be in groundwater, and pollution caused by human activities is the other important source of Be in groundwater, especially in the severely contaminated sites.

Relationship and Enrichment of Heavy Metals in Soil of Sewage Irrigation Area in Guangdong Province, China

The research reveals the relationship and enrichment of heavy metals in soil of sewage irrigation area in Guangdong province, southern China. Samples were collected from topsoil (0-10cm) and subsoil (30-40cm), and the total concentrations of heavy metals were extracted by HNO3-HF-HClO4. It is concluded that Cu, Zn, Cd, and Pb may be homologous or combined pollution, and Mn and Cr may be also homologous in soil. According to the result of cluster analysis, it is shown that Se and As may have the similar environmental geochemical behavior in topsoil, because the existing forms of them in environment are mainly acid anions. We can conclude that a significant degree of metal pollution exists in soil of sewage irrigation area, particularly for Cd, Cu, Pb and Zn. The degrees of contamination of heavy metals in topsoil (CF of Cd 8.1, Cu 7.0, Zn 5.9, Pb 3.6, Ni 2.1, As 1.8, Cr 1.6, Se 1.5) were higher than that in subsoil (CF of Cd 6.0, Cu 3.4, Zn 3.7, Pb 2.7, Ni 2.0, As 1.6, Cr 1.5, Se 1.4). EF values show deficiency enrichment with Ni, Se, Cr and As, low enrichment with Cu, Zn and Pb, and moderate enrichment with Cd in topsoil in study area, while deficiency enrichment with Ni, Se, Cr, Pb and As, and low enrichment with Cu, Zn and Cd in subsoil in study area.It should be recognized that the hazards posed by food production in sewage irrigation areas may become a common hazard for human.

Distribution of Heavy Metals in Groundwater of Sewage Irrigation Area in Guangdong Province, China

The research reveals the distribution and correlation of heavy metals in groundwater of sewage irrigation area in Guangdong province. 14 groundwater samples were collected in August 2008, and the groundwater samples were filtrated through 0.45 µm membranes and acidified in the field. Determinations of Cd, Cu, Zn, Pb, Ni, and Cr in all the samples were performed using ICP-OES, and determinations of As and Se in all the samples were performed employing HG-AFS. The result shows that the groundwater of sewage irrigation area has been contaminated with As and Ni, whereas the concentrations of other heavy metals (Pb, Zn, Cu, Cr, Cd, Se) in groundwater did not reach the upper limit for drinking water in China. High As concentrations in groundwater may due to the weak alkaline character of groundwater in sewage irrigation area, because groundwater with weak alkaline is beneficial to enrichment of As. According to correlation and cluster analysis, it is shown that Ni, Se, Zn and Cd may have the common source (sewage irrigation) or by chemical similarity in groundwater, Pb and Cu may have the similar environmental geochemical behavior in groundwater since they are chalcophile elements, whereas As is out of other heavy metals due to the pH of groundwater, because groundwater with weak alkaline is beneficial to enrichment of As, in contrast, for Pb, Cu, Zn etc. In addition, weak correlation relationships between pH and heavy metals concentrations in groundwater of study area suggest that heavy metals concentrations in groundwater of sewage irrigation area are not governed by simple relationships with pH.