不同镉污染消减措施对水稻-土壤镉累积的影响

Accumulation of Cadmium in Paddy Rice and Soil Affected by Different Reduction Measures

研究稻草还田/离田、清洁水灌溉与沉降截源等途径对水稻-土壤系统镉(Cd)累积的影响,对指导南方稻田土壤Cd污染治理、农业生产及粮食安全具有重要意义。采用田间微区试验,针对稻田Cd污染的主要输入和输出途径,设置稻草离田(T1)、清洁水灌溉+稻草离田(T2)、沉降截源+稻草离田(T3)3个Cd污染消减措施处理,并以稻草还田(CK)为对照,探究不同生育期的土壤和水稻各部位中Cd的分布与累积。结果表明,早稻和晚稻CK处理稻谷生物量分别为4 770kg·hm-2和3 912 kg·hm^(-2),与CK处理相比,3种消减措施处理早稻和晚稻稻谷生物量均有所下降,T1处理分别下降了1.6%和2.8%,T2处理降低了17.8%和6.5%,T3处理降低了10.5%与37.6%;不同生育期水稻籽粒、茎叶和根中Cd含量相对CK处理均有不同程度降低;T1～T3处理糙米Cd累积量较CK处理下降了19.7%～55.2%,茎叶中Cd累积量较CK处理下降了11.8%～37.1%,根系中Cd累积量较于CK处理下降了3.4%～52.0%,处理间均达到显著水平(P<0.05);成熟期不同处理间土壤pH值在4.44～5.21之间,不同消减措施处理土壤有效态Cd含量较CK处理早稻分别降低6.4%、5.4%和6.6%,晚稻分别下降6.4%、12.3%与8.3%,均无显著性差异(P<0.05)。由此说明3种Cd污染消减措施通过控制水稻-土壤系统Cd源输入和稻草Cd返还途径,使得水稻植株各部位Cd累积量、稻田土壤有效态Cd含量均呈现降低趋势,有利于南方稻田Cd污染防控和水稻安全生产。

Studying the effects of measures on the accumulation of cadmium(Cd)in rice-soil system including the straw returning/removing to the field,clean-up water irrigation and atmospheric deposition is of great significance to guide soil Cd pollution control,agricultural production and food security in southern paddy fields.In order to study the main inputs and outputs of Cd contamination in paddy field,a field experiment was performed to evaluate the effect of four measures on the accumulation of Cd in the soil-rice system,including the straw returning(CK),the straw removing(T1),clean water irrigation control with straw removing(T2)and atmospheric deposition control with straw removing(T3),and explore the distribution and accumulation characteristics of Cd in organs of rice and in soil at the different growth stages under the measures.The results showed that the brown rice biomass of CK treatment in early and late rice was 4 770 kg·hm^-2 and 3 912 kg·hm^-2,respectively.Compared with CK treatment,the other three measures reduced the biomass of brown rice,the T1 treatment was decreased by 1.6%and 2.8%,T2 treatment was decreased by 17.8%and 6.5%,T3 treatment was decreased by 10.5%and 37.6%in early and late rice,respectively.The Cd concentrations in roots,stem leaves and brown rice were reduced with different degree.However,the accumulations of Cd in brown rice were reduced by 19.7%-55.2%in T1-T3 treatment.Cd accumulations in stem leaves and roots system were decreased by 11.8%-37.1%and 3.4%-52.0%compared with CK treatment(P<0.05).All treatments were slightly different in pH,ranging from 4.44 to 5.21 at maturity.The available Cd concentration in soil was decreased by 6.4%,5.4%and 6.6%in the early rice seasons,as well decreased by 6.4%,12.3%and 8.3%in late rice seasons,which had no significant difference(P<0.05).The results showed that three Cd reduction measures could take the Cd inputs-outputs and Cd pathways of straw leave returning in control,resulting in a decreasing trend of Cd accumulation in various parts of rice and available Cd concentration in paddy soils.These three reduction measures are conducive to the prevention of Cd pollution in southern paddy fields and the safe production of rice.