Study On The Eco-environmental Geochemistry Of Arsenic-Fluorosis Area In Hubao Basin Of Inner Mongolia

Hubao Basin of Inner Mongolia is Meso-Cenozoic fault basin, which two kinds of disease-arsenic poisoning and fluorine poisoning exist; arsenic poisoning is mainly distributed in Zhijiliang township and around; fluorine poisoning is mainly distributed in Tuotketuo county, and all do serious harm to the health of residents.This paper has carried on 1:50000 eco-geochemical general investigation in Tuzuoqi Taosihao township-Zhijiliang township arsenic poisoning areas, Inner Mongolia, collected soil samples and rock samples, analysed the element content of As、F etc. The evaluation of Nemerow comprehensive pollution index and the evaluation of potential ecological hazards index showed that the area had been lightly polluted by heavy metals As, Cd, and F, Cd, Hg, As had larger potential hazard degree.Through the comprehensive study of the spatial distribution and factor analysis of soil harmful elements, the results showed that the soil had three kinds of pollution sources:(1) the overlay of the rock weathering, accumulation and the mining pollutes of the northwest adjacent region carried by rivers was the pollution source of Cr, Cu, Ni, Pb,Zn, F;(2) human activities(phosphate fertilizer use, villages and towns industry,living garbage) was the pollution source of Cd, Hg;(3) high arsenic rock weathering and accumulation was the pollution source of As.Through the epidemiology survey and ecosystem geochemistry survey of arsenic and fluorine disease village, collected surface water and groundwater samples, and measured water eco-geochemical indicators, water conventional content, heavy metals and measured groundwater 14 C age and D-O isotope, the results showed that Tuzuoqi Tiemengeng village and Zhijiliang village were the modest- severe arsenic disease areas; Tuoketuo county Zhanjiangying village and surrounding areas where fluorosis were serious; and As, Mn heavy metal pollution existed in water of the study area; the water was in an alkaline reduction environment; due to the strong evaporation, the As,F, mineralization, total hardness, electrical conductivity were relatively high. The groundwater was the ancient sealed water, and which had been measured the oldest age pleistocene period. Water arsenic content was 0.26-1354μg/L and over standard rate was 38.9%; water chemical type of rich arsenic water was Na-HCO3; Tuzuoqi rich arsenic water was in a weak alkaline and weak reduction environment; Tuoketuo county was in a strong alkaline and strong reduction environment; rich arsenic water was occurred in quaternary lake alluvium Q4 fl layer; the later structural trap was themain controlling factor for the enrichment of arsenic. Water fluorine content is0.03-7.14mg/L and over standard rate was 27.8%; water chemical type of rich fluorine water was Na-Cl+HCO3; the rich fluorine water was in a slightly alkaline and weak reduction environment; rich fluorine water was distributed in alluvial lacustrine plain or terrace discharge area where was low-lying, runoff lagging and finer particles aquifer; the shallow groundwater had the higher fluorine content;groundwater flow conditions, aquifer properties and depth, pH and redox environment were the main controlling factors for the enrichment of fluorine.