| Effect of different water (tertiary effluent, secondary effluent, raw sewage as well as tap water as control) used for irrigation on the qualities of crops (cucumber, cabbage and corn) and soil was investigated; meanwhile, the contents of residual chlorine ion, phosphate, nitrate and nitrite as well as residual heavy metals present in crops were studied respectively. The results demonstrated that the secondary effluent and tertiary effluent had no significant effect on the crop quality. In contrast, irrigation with raw sewage could lead to increase of partial nutrient components in the crops. If protein contents were taken as an example, the proteins for three crops corresponding to different water sources were in the range of 0.736?2～0.812?5 mg/kg for cucumber, 0.134?8～0.164?5 mg/kg for cabbage and 10.28～10.84 mg/kg for corn, respectively. Irrigation with sewage produced more accumulation of nitrates (554.4 mg/kg for cabbage). Considerable effects of irrigation with secondary effluent and tertiary effluent were not observed; however, sewage was not suitable for irrigation due to an apparent accumulation of heavy metals in crops. During short-period irrigation, sodium adsorption ratio (SAR) values of soil ranged from 3.5 to 4.5, suggesting that there was no concern on soil basification. As well, obvious accumulation of heavy metals in soils was not detectable. |
