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Xi X.,China Geological Survey | Li M.,China Geological Survey | Zhang X.,Hebei Institute of Geological Survey | Zhang Y.,Henan Institute of Geological Survey | And 4 more authors.
Earth Science Frontiers | Year: 2013

Soil organic carbon in middle-east China can be studied by comparison based on the data obtained by multi-purpose regional geochemical survey. The middle-east plain covers the terrain of Hebei, Henan, Hubei, Hunan, Guangdong and Hainan provinces, ranging from relatively higher latitude to low latitude and crossing temperate zone, subtropical zone and tropical zone. More than 334000 km2 were covered in the multi-purpose regional geochemical survey. Top soil (0-0.2 m) carbon storage is 906.84 Mt and average carbon density is 2716.93 t/km2. Including the higher soil carbon density in the northeastern plain, the carbon density in middle-east regions of China exhibited the changing pattern of high low high low from the northeastern plain downward to Hainan Province, that is 3327.8 t/km2 (northeastern plain)→2207.39, 2421.02 t/km2 (Hebei and Henan)→3442.15, 3942.92 t/km2 (Hubei and Hunan)→2255.90, 2936.72 t/km2(Guangdong and Hainan). The soil carbon density in agricultural ecosystem and urban ecosystem presented different changing rule from higher latitude to lower latitude, i.e., in agricultural farmland it changes from low to high, and in urban soil from high to low. The soil organic carbon increased by 14.5% (totally increasing 115.18 Mt and annually averaging 5.76 Mt/a) during past 20 years compared to the value achieved by the second soil reconnaissance. However organic carbon did not increase evenly. The rising rate decreased from low latitude to high latitude, and organic carbon increased in agricultural and urban ecosystem but decreased in tideland, rivers, lakes, grassland, forest and swamp. Source


Liu Z.-N.,Guangdong Institute of Geological Survey | Dou L.,Guangdong Institute of Geological Survey | Dou L.,Sun Yat Sen University | Zhang W.,Guangdong Institute of Geological Survey
Geological Bulletin of China | Year: 2012

Through a comprehensive analysis of the geochemical characteristics of the Quaternary sediments from 44 cores in the Pearl River delta plain in combination with grain sizes of the sediments, the authors studied the cadmium content of the Quaternary sediments in this area, which included distribution characteristics, source of high values, migration and enrichment. The result shows that: (1) cadmium values of the Quaternary sediments in different areas of the Pearl River delta plain are markedly different from each other, the main enrichment areas are Xijiang River and Beijiang River alluvial plains, and Tanjiang River and Dongjiang River alluvial plains constitute the background area; (2) the main factors that control the cadmium content of sediments in this area seem to be the source material, sediment grain size, sedimentary environment and organic matter. Xijiang River and Beijiang River alluvial plains are controlled by the Devonian and Carboniferous cadmium-rich sandstone and shale, while the Tanjiang River and Dongjiang River alluvial plains are constrained by the cadmium-poor Yanshanian granites. A distinct positive correlation is found between average particle size (ε) and cadmium content. Beside, warm and moist environment, intense land-sea interaction and rich organic matter are beneficial to the accumulation of cadmium-rich sediments; (3) weathering products of Cd-rich rocks, especially the well developed lead-zinc polymetallic ore deposits in the Xijiang River and Beijiang River basin, constitute the main source of cadmium high-value zone; and (4) the cadmium high-value zone of the Quaternary sediments in the Pearl River delta plain can be divided into northwestern and southeastern districts, which are constrained by the lead-zinc polymetallic ore deposits and the sedimentary environment of land-sea interaction respectively. Source


Li Y.,Sun Yat Sen University | Li Y.,Guangdong Provincial Key Laboratory of Geological Process and Mineral Resource Survey | Zhou Y.-Z.,Sun Yat Sen University | Zhou Y.-Z.,Guangdong Provincial Key Laboratory of Geological Process and Mineral Resource Survey | And 10 more authors.
Geological Bulletin of China | Year: 2010

In Shunde District of Foshan City, Pearl River Delta Economic Zone, 208 topsoil samples and 114 vegetable samples were collected from vegetable fields to measure the contents of lead (Pb), which species of 38 topsoil samples were extracted. The results showed that the average concentration of heavy metal Pb was 44.3 mg/kg. The contents of soil lead that exceeded Guangdong Province soil background values accounted for 77.5%, the content of lead in vegetable that exceeded safety requirements for non-environmental pollution vegetable accounted for 74.6%. The accumulation tendency of soil Pb of study area in the future 10 years was predicted based on the accumulation rate of soil Pb in 2007 which equaled to 1.02 mg/kg. Early-warning for the accumulation tendency of soil Pb were done based on the threshold values 150, 270, 300 and 8580 mg/kg, respectively. The scale which soil Pb in excess of 150 mg/kg was increased during 2007-2017 years, however, the scales were increased, which soil Pb in excess of 270, 300 mg/kg, respectively. There was a significant relation between the transfer factor values and the corresponding soil Pb concentrations (full dosage or bioavailable amount), which can be described by a plateau model. The target hazard quotients (THQs) can be used to evaluate the health risks with heavy metals by consuming vegetable. The THQs of Pb in vegetables were below 0.4 that values from large to small were THQhigh>THQurban >THQmedian>THQrural>THQlow, which indicated that the health risk via vegetable consumption in the high levels of family economic income was the highest. Moreover, further researches about influence of Pb on the human health through other exposure paths should be done. Source


Li Y.,Sun Yat Sen University | Li Y.,Guangdong Provincial Key Laboratory of Geological Process and Mineral Resource Survey | Zhou Y.-Z.,Sun Yat Sen University | Zhou Y.-Z.,Guangdong Provincial Key Laboratory of Geological Process and Mineral Resource Survey | And 9 more authors.
Huanjing Kexue/Environmental Science | Year: 2010

The index of local Moran's I is a useful tool for identifying hotspots of soil Ni and Cr, and for classifying them into spatial clusters and spatial outliers. To identify hotspots of vegetable soils Ni and Cr in high-incidence area of liver cancer, Shunde area of Foshan City, Pearl River Delta Economic Zone, 208 topsoil samples were collected from vegetable fields to measure the contents of nickel (Ni) and chromium (Cr). The results showed that the mean concentrations of two heavy metals Ni, Cr were 33.21 mg/kg, 80.84 mg/kg, respectively, Which were 130%, 60% higher than their soil background values of Guangdong Province, respectively. Generally, Ni is partly accumulated in soil but the accumulation of Cr is not obvious at all. The local Moran's I of Ni and Cr was calculated using 3000, 6000, 9000 m as distance bands, respectively. The hotspots of Ni and Cr elements in soils were identified by local Moran's I which computed based on 6000 m; "individual hotspots" are in the north which were affected by anthropogenic factors; "regional hotspots" are in the south which were controlled by parent materials. Moreover, the distributions of "regional hotspots" of Ni, Cr are the same as that of the highest mortality rate of liver cancer, this consistence could come up with a research direction that could reveal environmental etiologic factors of liver cancer. Source

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