Geochemical Characteristics Of Lead In Ecosystem And Its Influence On Human Health In Shunde Area Of Foshan City, The Pearl River Delta

Lead is one of natural poisonous heavy metal elements. It has important environmental meanings to study systematically characteristics of existing,distributing of lead and the relation between lead and regional epidemic.This research chose one of the three areas which had frequent liver cancers in the whole country——the Shunde and Nanhai in Foshan City as the research object. Then analysis total quantity of the lead in soil and drinking water, valid quantity and chemical element usefulness and its main impact factors. And evaluated background level of lead and excrescent degree in the area, analysis excrescent characteristics of lead and abnormality reason. Finally we find out the relationship between geochemistry environment and regional epidemic in the area.It is concluded that:(1) Lead contamination's degree was light in the study area. It attained second class of the National Soil Environment Standard. The total quantity content of lead in the surface layer of soil didn't related significantly to it in the deep soil. Total lead contents of most soil samples related significantly to pH value both surface layer and deep layer.(2) Compared Yangjiao village which is known as higher frequent liver cancer with Dazha village which has lower frequent liver cancer. The lead's total quantities of two soil sections have both obvious difference lengthways from 0 to 40 centimeters, they descend along with the depth adds. The total quantities of the lead in soil sections near the natural background value of the quality standard of the soil environment, and they don't change obviously along with the depth adds from 40 centimeters depth to the bottom. The lead's total quantities in 9 layers of the Dazha section are slightly higher at the same depth than them in the Yangjiao soil section.(3) Compared with the soil background value in the Nanhai district, the total lead average content of the agriculture soil in the research area is lower 27.6 mgs/kg than it in the Nanhai area, and the number is about 63.67% of Nanhai area. The total lead average content of agriculture soil in the Lecong town is close to it in the Jitang region of the Nanhai district, of the Shishan area in northeast Nanhai district and of the agriculture soil at south Danzao area in northeast Nanhai district.(4) The conclusions are as the following if the ground enrichment factors method and single factor index method are used: the pollution degree is light in the research area, and the distributing rule of pollution is not obvious. With the national natural background value of the soil and soil background in Guangdong province, a majority of surface layer soil was free from pollution, and small part had low to medium pollution in the study area.(5) The conclusions are as the following by adopting 7 extracts method: the highest metal availability (containing the water dissolve form, the exchangeability form, and the carbonate to combine form) is in the 19th point (in Dazha village) and in the 18th point (in Shuiteng village), they were more than 6 mg/kg. Secondly, in 9th, 11th, 17th, 16th and 3rd points, the availabilities were between 3.0 to 5.1 mg/kg. And the availabilities of 2nd (in Yangjiao village), 13th (in Shuiteng village) and 7th (in Luosha village) minimal, lower than 1 mg/kg.(6) The geography position of the lead valid form distributes were even inside the study district. The highest value appeared in the east and the southeast (in Dazha village); the lowest value appeared in the northwest hereabout Luosha village and Beiwei industrial area. In the frequent liver cancer area——Yangjiao, Luosha and Shuiteng village, the lead valid form distributed to have no obvious regulation. Contrast with Dazha village, the lead valid form value of the 2 areas was very close between the highest one and the lowest one.(7) Latent useful form contained the humic acid combine form, iron manganese to oxidize to combine form and strong organic combine form. The highest latent useful form is the 6th point (in Luosha village), for 40.03 mgs/kg is in the 4th point (in Yangjiao village) and the 13th point (in Shuiteng village). Secondly, at 30 to 40 mgs/kg scope. The 8th point (in Luosha village) was lowest, only 15.45 mgs/kg. The rest points of latent useful form were between 15 to 30 mgs/kg. Latent useful form with the relativity of total lead value very good.(8) Compared to the former study result of the geochemistry research in Shunde higher and lower frequent liver cancer area in 1987, the total quantity of the lead were on the low side in the surface layer agriculture soil and well. And the value range was inside of the former result. But the value scopes were the result scope gained by past study. The result we gained accord with the rule that the total quantity of the lead are minus the incidence of liver cancer. The cause of liver cancer formation without specially related relation by lead geochemistry characteristic in the Shunde area.