Arsenic Distribution In The Soil-crop System Irrigated With High Arsenic Water And Its Health Effects

Some paddy soils in Inner Mongolia Hetao plain are contaminated with arsenic (As) due to irrigation of As-laden groundwater, which elevated As transfer to the soil-plant system. We choose a sequential extraction procedure (SEP) for investigating the soil arsenic bioavailability in wheat crop. The G site irrigated by high arsenic groundwater, the Y site irrigated by Yellow River water.The total arsenic in surface soil of G site (18.8mg/kg) was obviously higher than that of the Y site (13.8mg/kg) and bioavailable As in surface soil increased by irrigating groundwater. In the five fraction of As in soil (F1-F5), As (F5) have great correlations (R>0.8, p<0.001) with the Fe (F5)、Mn (F5)、Al (F5). Arsenic concentration in wheat grain showed significant correlations with the exchangeable As (G site:R=0.71; Y site:R=0.61), and amorphous Fe oxides associated As evaluated by the SEP (G site:R=0.67; Y site:R=0.61), High arsenic water irrigation not only make the total arsenic content in wheat increased, the relative content of inorganic arsenic accounted for total arsenic increased. The results show that As in both fractions (F2、F4) was readily available for plant uptake and may pose a potential risk to the environment. Crystalline Fe oxides (F5) as the most stable, not easily affected by environment.72crop samples,81urine samples and8tap water samples were taken from4villages of the Hetao Basin of Inner Mongolia to evaluate the relationship between crop arsenic and human health risk. Results showed that arsenic concentration was less than1μg/L in tap waters. Arsenic concentrations in urine samples ranged from4.50to319μg/L with the mean value of56.9μg/L. DMA was the major As species, accounting for>70%total As. The main arsenic species were As(III)、DMA and As(V) in crops. The maximum As concentrations were102and335μg/kg for grain, vegetable and fruit samples, respectively. Accordingly, the maximum daily arsenic digested by adult and children were232and205μg, respectively. The relationship between crop arsenic, urine arsenic, and arsenicosis incidence indicated a potential health risk among the local residents, although levels of crop arsenic were not obviously greater than national guideline values. It suggested that after drinking water changed to the low arsenic tap water, human health risk may result from crop arsenic, instead of drinking water arsenic.