【摘要】 通过生物模拟法,将水稻幼苗分别暴露于含有10μmol/L无机三价砷As(Ⅲ)或五价砷As(V)的营养液中12,24,48h,探究硅砷摩尔比(Si/As为0∶1,100∶1和200∶1)对苗期水稻吸收、外排、转运和累积砷的影响。结果表明,水稻暴露于含As(Ⅲ)营养液中12h,与Si/As为0∶1相比,Si/As为200∶1的处理使水稻的As(Ⅲ)吸收速率降低30.7%(P<0.05),且随着暴露时间的延长,水稻对As(Ⅲ)的吸收速率逐渐降低,不同Si/As对其吸收速率的影响也减弱。处理48h,100∶1和200∶1的Si/As均降低水稻根部As(Ⅲ)向茎叶的转移系数,较Si/As为0∶1分别降低51.2%和56.9%,同时水稻地上部As(Ⅲ)含量比Si/As为0∶1的处理分别降低50.7%和67.2%;暴露在As(V)营养液中12h,Si/As为100∶1促进水稻对As(V)的吸收,增幅高达82.3%,但暴露24h,Si/As为200∶1则抑制水稻根系对As(V)的吸收,以及As(Ⅲ)的外排和As(Ⅲ)由水稻根系向茎叶的转运,降幅分别为28.0%,41.9%和39.9%。暴露48h时,Si/As为200∶1的水稻As(Ⅲ)转移系数较Si/As为100∶1的处理降低57.9%,并且处理24,48h时,Si/As为100∶1和200∶1水稻地上部As(Ⅲ)含量显著降低53.6%和75.0%,25.0%和52.8%。此外,水稻根系对As(V)的吸收与As(Ⅲ)的外排之间呈极显著正相关关系(r=0.921,P<0.01),该关系不受Si/As和暴露时间的影响。无论是As(Ⅲ)或As(V)处理,在12～48h的暴露时间内,Si/As为200∶1显著抑制砷的吸收、As(Ⅲ)的外排和As(Ⅲ)在水稻体内的转运。更多还原

【Abstract】 A hydroponic experiment was carried out to explore the effects of Si/As ratios(0∶1,100∶1 and200∶1)on the uptake,efflux,translocation and accumulation of arsenic in rice seedlings that were grown in nutrient solution containing 10μmol/L arsenite or arsenate for 12,24,48 h.The results showed that Si/As of 200∶1 reduced arsenite uptake rate compared to Si/As of 0∶1,accounting for 30.7%(P<0.05),when rice was exposed to nutrient solution with arsenite and silicon for 12 h.The uptake rates of arsenite of rice gradually decreased and the effect of different Si/As ratios reduced with the prolongation of exposure time.Furthermore,compared to Si/As of 0∶1,the ratios of Si/As at 100∶1 and 200∶1 inhibited the translocation of arsenite from roots to shoot and the concentrations of As(Ⅲ)were decreased by 51.2% and 56.9%,respectively,when rice seedlings exposed to nutrient solution with arsenite for 48 h,at the same time,the concentrations of As(Ⅲ)in rice shoots were significantly lower than Si/As of 0∶1,accounting for 50.7%and 67.2%,respectively.When rice seedlings were exposed to arsenate nutrient solution for 12 h,Si/As of100∶1 promoted the uptake rate of arsenate by rice,which was 82.3%higher than Si/As of 0∶1.However,the ratio of Si/As of 200∶1 inhibited the uptake rates of arsenate,arsenite efflux by rice roots and translocation of As(Ⅲ)after 24 hfor exposure to asenate,accounting for 28.0%,41.9%and 39.9%,respectively.The translocation of As(Ⅲ)from root to shoot with Si/As of 200∶1 was 57.9%lower than that of Si/As of 100∶1 after 48 hof exposure time.In addition,the concentrations of As(Ⅲ)in rice shoots in the treatment of Si/As ratio at100∶1 and 200∶1 for 24 hor 48 hwere significantly lower than the control,accounting for 53.6% and75.0%,25.0% and 52.8%.In addition,there was a significant positive correlation between the uptake of As(V)and the efflux of As(Ⅲ)in rice roots(r=0.921,P<0.01),which was not affected by Si/As and exposure time.In summary,when rice seedlings were exposed in nutrient solution with As(Ⅲ)or As(V)for12～48 h,the ratio of Si/As at 200∶1 significantly inhibited arsenic uptake,As(Ⅲ)efflux and translocation of As(Ⅲ)from root to shoot in rice.更多还原