沼液施灌模式下稻田系统重金属风险评估

Risk Assessment of Heavy Metals in the Paddy Field System Under theMode of Biogas Slurry Irrigation with Fertilization

为明确沼液替代化肥对环武夷山国家公园保护发展带稻田生产系统重金属的影响,以光泽县山头村单季稻稻田为样地,设置了100%化肥(T_(1))、50%化肥+50沼液(T_(2))、50%化肥+100%沼液(T_(3))、50%化肥+200%沼液(T_(4))4个处理,应用单因子评价稻米生态风险指数(P_(i)),应用Hakanson法评价土壤重金属潜在生态污染风险指数(R_(I))。结果表明:试验稻米未发现重金属风险,其中P_(Cd)<0.005,P_(Hg)为0.450~0.700,P Cr为0.009~0.014,P_(As)为0.080~0.166,P_(Pb)为0.110~0.325。土壤重金属潜在生态污染风险指数(R_(I))为203.5~269.9,主要污染风险来源于Hg和Cd,两种重金属相对富集系数分别为227.0%~349.2%,250.0%~363.3%。与种植前比较,T_(2)处理的R_(I)提高11.9,但是T_(1)、T_(3)、T_(4)处理的R_(I)则分别下降56.9、11.3、18.2,T_(2)处理的潜在生态污染风险主要为Cd。

In order to clarify the effect of biogas slurry replacing the chemical fertilizers on heavy metal in the production system of paddy field in the protection and development belt surrounding Wuyishan National Park four treatments including 100%chemical fertilizer(T_(1)),50%chemical fertilizer+50 biogas slurry(T_(2)),50%chemical fertilizer+100%biogas slurry(T_(3)),and 50%chemical fertilizer+200%biogas slurry(T_(4))were set up by using the paddy field of single-cropping rice in Shantou Village of Guangze County as the sample plot.The ecological risk index(P_(i))of rice was evaluated by using the single factor,and the potential ecological pollution risk index(R_(I))of heavy metals in soil was evaluated by using the Hakanson method.The results showed that:the risk of heavy metals was not found in the experimental rice,No risk of heavy metals was found in the experimental rice,among which P_(Cd) was less than 0.005,P Hg ranged from 0.450 to 0.700,P Cr ranged from 0.009 to 0.014,P As ranged from 0.080 to 0.166,and P Pb ranged from 0.110 to 0.325.The potential ecological pollution risk index(R_(I))of soil heavy metals ranged from 203.5 to 269.9,and the main pollution risks came from Hg and Cd.The relative enrichment coefficients of the two heavy metals were 227.0%-349.2%and 250.0%-363.3%,respectively.Compared with the indicators before planting,R_(I) of T2 treatment increased by 11.9,but R_(I) of T1,T3 and T4 treatment decreased by 56.9,11.3 and 18.2,respectively.The potential ecological pollution risk of T2 treatment was mainly Cd.