Influence of wastewater irrigation on environmental capacity of soil heavy metals and rice growth

The pollution status of soils and wastewater were studied in cultivated fields．The results show that the soil contents of CA ，As ，Hg，Cu，Pb，Cr and Zn are 1．55～5．29 times of those of the background values，an d those of Cd and As are up to 3 and 1．42 times of the environmental quality standard values of the second leve1．The heavy metal contents in wastewater are 4．8 to 34 times of the standard values for irrigation water quality，and the contents of some organic pollutants&re also higher than those of the standard．If thinking the third level standard values of environmental capacity as the maxirnum limitation，the sequence of heavy metals reaching the limitation of wastewater irrigation years is Cr> Hg>Pb>Cu>Zn>CA ．Both polluted soil irrigated by natura1．water and unpolluted soil irrigated by wastewater will Mfeet the rice growth，and polluted soil irrigated by wastewater can lead to the death of some rice seedlings．