Occurrence Mode And Ecological Effects Of Fluorine In The Piedmont Region Of Taihang Mountain

Fluorosis is relative severe in Hebei Province, so the analyzing about a series of geochemical problems of the fluorine element has important practical significance on figuring out the root causes of fluorosis and relieving the disease.Based on the data from 1:250000 multi-purpose geochemical survey to the plain area of Hebei Province, the distribution and enrichment of the fluorine in soil,groundwater,the main crop seeds were discussed, and so were the other thing, such as the fluorine anomalies delineated and the factors of its forming, the source of the element, occurrence pattern, migration and transformation and its ecological effects. The analysis above provides a theoretical basis for government decision-making and the prevention and control of the fluorosis. Some new understandings were concluded as follows:1. There is a north east high fluorine content zone both in topsoil and in deep-soil in the piedmont of the Taihang mountain, which were mainly located in Baiyangdian depression, Ningjinbo-Daluze depression, Cangzhou Qingxian to Hengshui Wuqiang and the coastal areas of Cangzhou, etc.The content of the fluorine is relatively high in some swamp soil and saline which was formed from marine or lake or swamp sedimentary and relatively low in some sandy soil and new plot soil. Parent rocks and the natural geological features which complement and impact with each other dominated the geochemical landscape of the fluorine element. In the study area also showed a north east high fluorine content zone about the shallow groundwater, mainly located in the central depression at the edges of flood plains and alluvial fans, interactive areas of land and sea, on both sides of the ancient river areas in Hejian, etc. The content of fluorine element is generally high in deep groundwater, and most of the samples exceed the standard of drink water, and also in some area is more then 4 mg/L about the fluorine content.2. The analysis about the fluorine anomalies in soil shows that the anomalies are mainly controlled by the natural background, and the contribution of the natural source is relatively high, up to 71.66%～91.04%. Fluorine anomalies of shallow groundwater are mainly attributed to the primary natural abnormalities, and the fluorine element of the shallow groundwater mostly comes from the base rocks of the Taihang Mountain and minerals in the unconsolidated sediments during the Quaternary in plain, the minerals are often rich in fluorine element. Some factors, such as the poor conditions about recharge, runoff and discharge, shallow depth, drought weather, strong evaporation, soil salinization, high salinity of the groundwater and so on, contributed to the formation of high fluorine content water.3. There are multiple sources of fluorine element in soil and groundwater in the Piedmont of the Taihang Mountain. Bedrocks in the Taihang Mountain, volcanic activities and transgressive in Quaternary, and floodings of the Yellow River are the natural sources, while irrigation water, fertilizer, atmospheric dust are the main man-made sources. The sources above have important effect on the distribution and enrichment of the fluorine element in soil and groundwater.4. Fluorine element in soils mainly occurs in clay minerals, particularly in illite or in illite-imon mixed layer minerals. In the study area, the fluorine element occurs in the three main patterns, F-, CaF+, MgF+, due to the neutral or alkaline (pH value 7-8)of the shallow groundwater.5. The fluorine content in wheat and corn seeds are both lower then the limited value of the national green food standard, completely belongs to green agricultural products.Fluorine element in wheat and corn seeds occurs in a low extent of enrichment, and the enrichment is affected by many factors, such as the fluorine content in root-soils, physical and chemical properties about the soil, the fluorine in irrigation water, fertilizer, atmospheric dust, and the different abilities of the crops taking fluorine element. The fluorine content of the soil in the study area mainly occurs in the states of moderate and rich, and local soil appeared very lack or very rich. Fluorine-quite -rich areas are mainly located in Cangzhou, Handan, and local areas in Langfang, Hengshui and Xingtai, where is rightly more sever in fluorosis. So it should be paid more attentions.6. Daily intake of fluorine and health risk assessment showed that the daily intake of fluorine in the region is lower than the recommended ADI value (2mg/ (persons. D) by World Health Organization, and also lower than the limited value (3.5mg) regulated by China Ministry of Health. As to the ways of fluorine intake, water plays an more important role. In the study area, there are a large area of high fluorine content groundwater, especially deep groundwater, which may be the major cause of high fluorosis incidence in Hebei Province.