HUANG Chenchen1, ZHANG Chipeng1,2, DUAN Mingyu1, WU Pan1,2
（1.School of resources and environmental engineering, Guizhou University, Guiyang 550025, China；
2.Key Laboratory of Process and Control of Mining Environmental Pollution Colleges and Universities in Guizhou Province, Guiyang 550025, China）
Abstract: The study was designed to explore the influences of cattle manure on arsenic uptake by rice grain. The pot experiments were conducted to investigate effects of cattle manure on activities of arsenic and iron in soils, formation of iron plaque on the rice root surface and arsenic contents in rice grains. When the amount of cattle manure added to polluted soils and background soils increased, the DOC contents and pore water pH of soils increased, while Eh of soils decreased. The addition of cattle manure could activate iron and arsenic in soils. The contents of Fe(II), AO-Fe and HCl-As in polluted soils increased by 13.5~149%、35.9~ 90.9% and 70.1~181%, respectively, which were 0.86~1.66, 1.17~2.15 and 4.29~8.91 times higher than those of background soils. The application of cattle manure could also promote the formation of iron plaque on the root surface. The iron contents on the root surface were 1.56~1.96 times higher for polluted soils and 2.09~3.07 times higher for background soil compared to their control experiments during the jointing stage. The contents of adsorbed As in polluted soils and background soils were 3.04~5.18 times and 3.82~4.08 times, respectively, higher than their controls. The iron contents on the root surface increased first and then decreased when the amount of cow manure adding kept increasing. Iron and arsenic adsorbed on the root surface in polluted soils were 1.35~2.91 times and 8.45~16.6 times, respectively, higher than those in background soils at the maturity stage. The molar ratio of arsenic and iron on the rice root surface in polluted soils ranged from 3.49×10-3 to 3.55×10-3, while ranged from 4.41×10-4 to 6.17×10-4 in background soils. The arsenic contents in rice grains from background soil experiments decreased about 36.4%, but the arsenic contents in rice grains from polluted soil experiments increased about 127% after adding cattle manure. The results suggested that adding cattle manure has significant effects on activities of arsenic and iron in soils, formation of iron plaque on the rice root surface, and arsenic contents in rice grains. The cattle manure should be cautiously used as fertilization in paddy fields polluted by the mining drainage with the high content of arsenic.
Key words: cattle manure; paddy soil; rice; arsenic pollution; iron and arsenic transformation
EARTH AND ENVIRONMENT Vol.48, No.1, Tot No.333, 2020, Page 24-29