Occurrence and assessment of polycyclic aromatic hydrocarbons in soils from vegetable fields of the Pearl River Delta, South China

Surface soil (0-20 cm) samples from nine representative vegetable fields located in Guangzhou, Shenzhen, Zengcheng and Huadu within the Pearl River Delta, South China were collected and analyzed for 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography coupled to mass spectrometry (GC-MS). Total concentrations of 16 PAHs (Sigma(PAHs)) ranged from 160 to 3700 microg kg(-1). Large variations were observed also between concentrations of individual PAHs from different vegetable fields and within the site as well. Acenapthylene, benzo[b]fluoranthene, fluoranthene, benzo[a]pyrene and benzo[k]fluoranthene were consistently the most prevalent individual PAHs. The values of PAH isomer ratios [anthracene/(anthracene+phenanthrene) and fluoranthene/(fluoranthene+pyrene)] indicate that combustion processes are the major sources of PAHs. Concentrations of PAHs were poorly correlated with organic carbon concentrations of soils, suggesting different sources and also indicating that the PAH pollution of this area is recent. The same outcome is confirmed by the predominance of PAHs with fewer rings (相似文献   

Heavy metals in agricultural soils of the Pearl River Delta,South China

There is a growing public concern over the potential accumulation of heavy metals in agricultural soils in China owing to rapid urban and industrial development and increasing reliance on agrochemicals in the last several decades. Excessive accumulation of heavy metals in agricultural soils may not only result in environmental contamination, but elevated heavy metal uptake by crops may also affect food quality and safety. The present study is aimed at studying heavy metal concentrations of crop, paddy and natural soils in the Pearl River Delta, one of the most developed regions in China. In addition, some selected soil samples were analyzed for chemical partitioning of Co, Cu, Pb and Zn. The Pb isotopic composition of the extracted solutions was also determined. The analytical results indicated that the crop, paddy and natural soils in many sampling sites were enriched with Cd and Pb. Furthermore, heavy metal enrichment was most significant in the crop soils, which might be attributed to the use of agrochemicals. Flooding of the paddy soils and subsequent dissolution of Mn oxides may cause the loss of Cd and Co through leaching and percolation, resulting in low Cd and Co concentrations of the paddy soils. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the Fe-Mn oxide and residual fractions, while Zn was predominantly found in the residual phase. A significant percent fraction of Cu was bound in the organic/sulphide and residual phases. Based on the 206Pb/207Pb ratios of the five fractions, it was evident that some of the soils were enriched with anthropogenic Pb, such as industrial and automobile Pb. The strong associations between anthropogenic Pb and the Fe-Mn oxide and organic/sulphide phases suggested that anthropogenic Pb was relatively stable after deposition in soils.     

Occurrence, sources, and inventory of hexabromocyclododecanes (HBCDs) in soils from Chongming Island, the Yangtze River Delta (YRD)

Hexabromocyclododecanes (HBCDs) is a concern due to their large usage combining with physico-chemical properties and toxicity to wildlife and human. However, very limited data were reported on HBCDs in soils, especially from rural area. In this study, 22 soil samples were collected from Chongming Island at estuary of the Yangtze River Delta, to investigate the level, diasteroisomer profile, potential sources, and mass inventory of HBCDs. The total concentrations ranged from not detected to 93.8 pg g⁻¹ dry weight (dw) with a mean of 23.3 pg g⁻¹ dw, which was at the low end of the global levels. The wide distribution of HBCDs in soils suggested that the local emissions of HBCD-containing materials and/or the inputs via atmospheric transport from other regions were two possible sources. Variation of HBCDs levels was observed in different types of soils. Woodland, tideland and road soils contained slightly higher HBCDs than those of farmland and grassland. Overall, γ-HBCD was the dominant diasteroisomer in soils, followed by α-HBCD and β-HBCD. Significant but weak correlations were only found between α-HBCD and β-HBCD versus TOC content in soils. Currently, the mass inventory of HBCDs in soils of Chongming Island was 5.3 kg. Based on these data, we gave perspective on human intake of HBCDs via soil ingestion by age. Local resident’s intakes ranged from 15.5 to 97.8 fg kg body weight⁻¹ d⁻¹, in which children are exposed more than adults.     

PCB contamination in soils of the Pearl River Delta, South China: levels, sources, and potential risks

Polychlorinated biphenyls (PCBs) contamination in tropical and sub-tropical areas and the associated risks have attracted great concern. A total of 69 samples representing five distinct land types were collected to assess PCB concentrations in the Pearl River Delta (PRD), South China, including spatial distributions in soils of the area, the probable anthropogenic sources, and related potential risks. PCBs concentrations in soils of the PRD ranged from 0.3 to 202 ng?g^?1. More severe PCBs contamination was presented in the western part than in the eastern part of the PRD region. The PCBs were dominated by low-chlorinated biphenyls; however, the proportion of higher-chlorinated biphenyls was elevated with the influence of industrial activities. Principal component analysis indicated that PCBs contamination in soils of the PRD region was mainly associated with 1#PCBs, while 2#PCB and e-waste emission in South China also accounted for it partly, especially to the industrial activity severely impacted areas. Toxic equivalent (TEQ) of the dioxin-like PCBs in the soils indicated that higher risk of PCB contamination was presented in the Dongjiang River Valley (55 ng?TEQ?kg^?1, on average) than in the Xijiang River Valley, and were mostly contributed by the congener of PCB126.     

Polybrominated diphenyl ethers in background surface soils from the Yangtze River Delta (YRD), China: occurrence,sources, and inventory

Purposes  

Very few data for polybrominated diphenyl ethers (PBDEs) were available in the Yangtze River Delta (YRD), one of the most developed and urbanized region in China. In this study, Chongming Island, located at the estuary of the Yangtze River, was selected as background area to investigate the occurrence, sources, and inventory of PBDEs.     

Nitric oxide emission from a typical vegetable field in the Pearl River Delta, China

Croplands contribute to atmospheric nitric oxide (NO), but very limited data are available about NO fluxes from intensively managed croplands in China. In this study, NO fluxes were measured in a typical vegetable field planted with flowering Chinese cabbage (Brassica campestris L. ssp. Chinensis var. utilis Tsen et Lee), which is the most widely cultivated vegetable in Guangdong province, south China. NO emission drastically increased after nitrogen fertilizer application, and other practices involving loosening the soil also enhanced NO emission. Mean NO emission flux was 47.5 ng N m⁻² s^–1 over a complete growth cycle. Annual NO emission from the vegetable field was about 10.1 kg N ha⁻¹ yr⁻¹. Fertilizer-induced NO emission factor was estimated to be 2.4%. Total NO emission from vegetable fields in Guangdong province was roughly estimated to be 11.7 Gg N yr⁻¹ based on the vegetable field area and annual NO emission rate, and to be 13.3 Gg N yr⁻¹ based on fertilizer-induced NO emission factor and background NO emission. This means that NO emission from vegetable fields was approximately 6% of NO_x from commercial energy consumption in Guangdong province.     

Ecological risks and potential sources of heavy metals in agricultural soils from Huanghuai Plain, China

A total of 224 agricultural soil samples from Huanghuai Plain in China were investigated for the concentrations of seven heavy metals (As, Cd, Cr, Hg, Ni, Pb, and Zn). The mean concentrations of the metals were 12, 0.17, 79, 0.04, 35, 25, and 74 mg/kg, respectively. These values are similar or slightly higher than background values in this region, except for Cd with a mean nearly twice the background value. The estimated ecological risks based on contamination factors and potential ecological risk indexes are also mostly low, but considerable for Cd and Hg. Multivariate analysis (including Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed three distinct metal groups, i.e., Cr/Ni/Zn, As/Cd/Pb, and Hg, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the plain. The main anthropogenic sources for the three metal groups were identified as atmospheric deposition, sewage irrigation/fertilizers usage, and atmospheric deposition/irrigation water, respectively. The present results are well suited for planning, risk assessment, and decision making by environmental managers of this region.     

Trophic relationships and health risk assessments of trace metals in the aquaculture pond ecosystem of Pearl River Delta,China

Cadmium, lead, zinc, Chromium, copper, nickel and manganese in sediments and in aquatic organisms were collected from the aquaculture pond ecosystem of the Pearl River Delta (PRD), China and analyzed to evaluate bioaccumulation and trophic transfer in food chains, as well as the potential health risk of exposure to the Hong Kong residents via dietary intake of these aquatic products. The results revealed that based on the biota–sediment accumulation factor, omnivorous fish and zooplankton accumulated more trace metals from sediment than carnivorous fish. Concentrations of seven trace metals in aquaculture pond of PRD significantly decreased with increasing trophic levels, showing that these trace metals were trophically diluted in predatory and omnivorous food chains. The hazard index values of all fish species were smaller than 1 for adults and children, indicating there was no health risk from the multiple metals via ingestion of the freshwater fish for the inhabitants.     

Occurrence and risk assessment of trace metals and metalloids in sediments and benthic invertebrates from Dianshan Lake,China

Environmental Science and Pollution Research - The present study measured concentrations of Cr, Ni, Cu, Zn, As, Cd, Sb, and Pb in surface sediments and two benthic invertebrate species (Anodonta...     

Characterization of extractable and non-extractable polycyclic aromatic hydrocarbons in soils and sediments from the Pearl River Delta, China

Formation of bound residues of pollutants in soils and sediments is an important process to control the fate of pollutants in the environment. The most of bound residue is not solvent extractable. In this paper, we measured both extractable and non-extractable polycyclic aromatic hydrocarbons (PAHs) in different organic matter fractions of samples from the Pearl River Delta, China. Non-extractable PAHs concentration was 234.45-1424.57 μg/kg and accounted for 33.78-57.44% of total PAHs. 2-3 Ring PAHs were the dominant species and differed in concentration substantially between the samples. The atomic ratio of PAHs over organic-C in the fractions ordered as solvent soluble organic matter > humin > humic acids, matching the content of aliphatic moieties in the fractions of organic matter. The ratio of extractable and non-extractable PAHs may relate to the aging process of PAHs in soil and sediment.     

Levels and isomer profiles of Dechlorane Plus in the surface soils from e-waste recycling areas and industrial areas in South China

Dechlorane Plus (DP) is a highly chlorinated flame retardant. Levels of DP were measured in surface soils from e-waste recycling areas and industrial areas in South China. Higher DP levels were found in e-waste recycling areas (undetectable-47.4 ng/g) than those in industrial areas (0.0336-4.65 ng/g) in South China. The highest DP concentration (3327 ng/g) was found at the e-waste recycling site in Qingyuan, while DP levels fell dramatically with increasing distance away from the recycling site, suggesting that the e-waste recycling activities are an important source of DP emissions. The mean ratios of anti-DP to total DP (f_anti) for different sampling areas ranged from 0.58 to 0.76 and showed no significant difference from the ratio for the technical DP products (t-test, p > 0.05). Further intensive studies are needed to investigate the process of DP degradation and its degradation products.     

Occurrence and distribution of sediment-associated insecticides in urban waterways in the Pearl River Delta, China

Sediment-associated pesticides, including organochlorine (OCP), organophosphate (OP), and pyrethroid insecticides, were analyzed in urban waterways in three cities (Guangzhou, Dongguan, and Shenzhen) in the Pearl River Delta (PRD), China. The OCPs represented 27.2% of the detectable insecticides in sediment, and chlordanes, DDTs, and endosulfans were the most frequently detected OCPs. The currently used insecticide chlorpyrifos was the only OP detected above the reporting limit (RL), with concentrations ranging from <RL to 100 ng g⁻¹ dry weight (dw). Additionally, pyrethroids were detected in all sediments with the sum pyrethroid concentrations ranging from 4.26 to 384 ng g⁻¹ dw and this represented 64.9% of the sum insecticide concentration. Despite their widespread use, no studies have been conducted investigating the occurrence and distribution of pyrethroids in China. As the first report of pyrethroids in urban waterways in China, the current study found cypermethrin was the most abundant insecticide detected in the PRD at concentrations ranging from 1.44 to 219 ng g⁻¹ dw. Spatially, sediment from more populous and urbanized areas (Shenzhen and Tianhe district in Guangzhou) had higher insecticide residues than less populous agricultural areas. In the more modernized city of Shenzhen, the OCPs were seldom detected, whereas more diverse patterns of pyrethroids were observed. Potential sources of these insecticides, especially the frequently detected pyrethroids, were most likely from pest control during urban landscaping maintenance and from abatement programs targeting mosquitoes and ants. Results suggested that a shift in application pattern and elevated urbanization increased accumulation of currently used insecticides like pyrethroids in sediment, and made them the predominate insecticides in the PRD urban waterways.     

Occurrence and possible sources of polychlorinated biphenyls in surface sediments from the Wuhan reach of the Yangtze River, China

Twenty-seven surface sediment samples were collected from the mainstream and eight tributaries of the Wuhan reach of the Yangtze River, China, in 2005, in order to assess the distribution, possible sources, and potential risk of polychlorinated biphenyls (PCBs) in the environment. The total concentrations of PCBs (the sum of 39 congeners) ranged from 1.2 to 45.1 ng g⁻¹ dry weight, with a mean value of 9.2 ng g⁻¹. Sediment samples with the highest PCB concentrations came from the tributary sites, which are closer to PCB sources. Conversely, PCB concentrations in the sediment from the mainstream sites of Yangtze River were relatively low. The observed PCB levels were higher than those found in the sediments of other rivers in China, but lower than those in river sediments from other urban areas and harbors around the world. Low-chlorinated PCBs, dominated by tetra-PCBs and penta-PCBs, were identified as being prevalent in the surface sediments. Correlation analyses between the PCBs and the geochemistry and heavy metal content of the sediments suggest that the washing of these compounds from the land into the river by floods and heavy rains, or industrial wastewater and domestic sewage, may be the major sources of the PCBs. According to established sediment quality guidelines, the risk of adverse biological effects from the levels of PCBs recorded at most of the studied sites should be insignificant, although the higher concentrations at other sites could cause acute biological damage.     

Visual range trends in the Yangtze River Delta Region of China, 1981-2005

Visual range (VR) data from 1981 to 2005 were examined for 20 meteorological monitoring sites in the Yangtze River Delta Region of China. Cumulative percentile analysis was used to construct VR trend. The 25-yr average domain-average 50% VR was approximately 21.9 +/- 1.9 km. Domain-average 50% VR decreased from 1981 to 2005 with a trend of -2.41 km/decade. The worst 20% and 50% and best 20% VR and variation rates for the 20 sites were analyzed. The 50% VR of the town, county-level city, and prefecture-level city sites were 24.1, 21.5, and 19.4 km, respectively. The best 20% VR decreased fastest with a rate of -3.5 km/decade. Regional median VR decreased from the coastal sites to the inland sites. Ridit analysis and cumulative percentile were adopted to study the VR variation properties between economically developed areas (e.g., Nanjing and Hangzhou) and remote areas (e.g., Lvsi). The two analyses show that VR decreased in Nanjing and Hangzhou but remained constant in Lvsi from 1981 to 2005.     

Occurrence, possible sources, and temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in water and sediment from the lower Yangtze River basin, Jiangsu and Shanghai areas of Eastern China

The concentrations, compositional profiles, and possible sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) in water column and surface sediment samples from the lower reaches of the Yangtze River were investigated, and the potential risks posed by these chemicals were evaluated. Concentrations of the 17 2,3,7,8-substituted PCDD/PCDF in the water and sediment samples ranged from 0.45 to 10.0 pg TEQ/L (mean 2.34 pg TEQ/L) and from 0.31 to 51 pg TEQ/g dw (mean 5.25 pg TEQ/g dw), respectively. Water and sediments from the Nanjing–Nantong sections of the Yangtze River were found to have elevated PCDD/PCDF levels, and the PCDD/PCDF TEQ concentrations in 13 sediment samples exceeded the probable effect levels (PEL), above which adverse biological effects are likely. Multivariate statistical analysis indicated that the principal PCDD/PCDF contamination source for the water and sediment was the production and use of pentachlorophenol (PCP) or sodium pentachlorophenate (PCP-Na). PCDD/PCDF concentrations were stable over time near the Yangtze River Estuary but had increased sharply in recent decades in the Nanjing–Nantong section, which will have been related to the growth in industrial activities and other anthropogenic PCDD/PCDF sources. Total organic carbon (TOC) and PCDD/PCDF concentrations correlated significantly (R?=?0.474, P?<?0.01), suggesting that TOC plays an important role in the transport and re-distribution of PCDD/PCDF in the Yangtze River basin.     

Diffusion pollution from livestock and poultry rearing in the Yangtze Delta,China

BACKGROUND: The Yangtze Delta is one of the most developed regions in China and includes Shanghai, eight cities in Jiangsu province and eight cities in Zhejiang province. Meat consumption in this region has increased with economic growth, and most of the consumed meat is produced locally. The water quality of surface waters has deteriorated in recent years. An example was the huge blue-green algae bloom in Tai Lake in late May 2007, which affected millions of people's daily drinking water. However, animal husbandry is considered to be one of the main pollution sources. METHODS: Pollutants (NH3-N, total phosphorus (TP), and total nitrogen (TN)) excreted by livestock and poultry, and the resultant COD (chemical oxygen demand) and BOD (biochemical oxygen demand), were estimated using two different methods based on different data sets. RESULTS: The number of livestock and poultry has remained stable in the Yangtze Delta over the four years from 1999 to 2002, with the average number of pigs, cattle, sheep and poultry being 21.1 M, 0.4 M, 7.7 M and 597.6 M, respectively. Pollutants in livestock and poultry excreta estimated by Method I were: 0.12 Mt NH3-N, 0.11 Mt TP and 0.29 Mt TN, resulting in COD and BOD of 1.34 Mt and 1.30 Mt, respectively, while the estimations based on Method II were: 0.18 Mt NH3-N, 0.15 Mt TP and 0.40 Mt TN, resulting in COD and BOD of 1.95 Mt and 1.80 Mt, respectively. DISCUSSION: Pollutants excreted annually by livestock and poultry in the Yangtze Delta are estimated to be: 0.17 Mt NH3-N, 0.16 Mt TP and 0.42 Mt TN, giving rise to a COD of 1.86 Mt and a BOD of 1.72 Mt. Approximately 25% of this pollution was estimated to enter water bodies, which means that the annual pollutant load is 43,700 t NH3-N, 39,400 tTP, 104,600t TN with a COD of 465,000 tand a BOD of 430,100 t. Pollutants from animal husbandry were similar in magnitude to those from industrial wastewater. Pigs produced the most pollution, followed by poultry, cattle and sheep. The pollution load from animal husbandry in the Yangtze Delta is about twice the average level of the whole of China. CONCLUSIONS: Domestic wastewater was the main pollution source in the Yangtze Delta, followed by pollution from raising livestock and poultry and from industrial wastewater. The pollution load in Shanghai and Jiaxing were the greatest, followed by 7 cities of Jiangsu province (except Suzhou) and other cities of Zhejiang province and Suzhou. Pigs and poultry produced about 90% of the total pollutants from animal husbandry. RECOMMENDATIONS AND PERSPECTIVES: The local governments, especially in Shanghai and Jiaxing, should focus their attention on the pollution produced by livestock and poulrry. Controlling pollution from pigs and poultry will have the greatest impact in this region. Control of pollution will be facilitated by the development of large-scale livestock and poultry farming units and a shift away from small scale husbandry.     

Heavy metals in agricultural soils from Piedmont,Italy. Distribution,speciation and chemometric data treatment

The distribution and speciation of heavy metals in five agricultural soils of Piedmont Region (north-western Italy) were investigated. Ten metals, namely Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Ti and Zn were considered. Analytical determinations were performed by atomic emission or atomic absorption spectroscopy after microwave sample dissolution in acid solution. Total metal concentrations fit in the typical concentration ranges for unpolluted soils, with the exception of cadmium and lead content in some horizons. The effect of sampling depth on concentrations was discussed. Speciation studies were carried out by applying Tessier's procedure, which allows to subdivide the total metal content into five fractions, representing portions bound to different components of the soil. Moreover, the element labilities in two soils were evaluated by extraction with EDTA. Correlations among the variables and/or similarities among the sampling points were identified by principal component analysis and hierarchical cluster analysis.     

Polycyclic aromatic hydrocarbons in soils in the vicinity of Nanjing, China

The occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in vegetable soils from five vegetable fields (including: Liuhe, Xixia, Pukou, Jianye and Yuhua districts) in Nanjing outskirt were investigated with high performance liquid chromatography (HPLC) equipped with fluorescence detector. The total concentrations of 15 priority PAHs in 126 soil samples ranged from 21.91 to 533.84ngg(-1) dry weight, and the sum of seven carcinogenic PAHs concentrations varied from 1.48 to 236.19ngg(-1) dry weight. Statistical analysis of the PAHs concentrations showed that the highest PAHs concentration was observed in Liuhe, and the lowest PAHs concentrations were found in Xixia among the five districts. The ratios of fluoranthene to sum of fluoranthene and pyrene concentrations (Flt/(Flt+Pyr)) were more than 0.5 in 99% of vegetable soil samples, showing that the PAHs in soils were generally derived from straw and coal combustion sources. The results from principal component analysis (PCA) further indicated that extensive combustion activities affected the PAHs distribution in Nanjing vegetable soils.