叶面喷施铈硅复合溶胶抑制生菜砷积累效应研究

采用水热合成法,利用正硅酸乙酯和硝酸铈分别制备了二氧化硅和二氧化铈溶胶。通过土培盆栽试验,在广东省汕头市莲花山钨矿区砷污染土壤上种植意大利生菜,研究了叶面喷施不同浓度二氧化硅、二氧化铈以及不同掺杂比的铈硅复合溶胶对生菜地上部生物量、叶绿素含量、砷含量以及生菜地上部砷积累量的影响。结果表明：叶面喷施不同浓度铈、硅溶胶及不同掺杂比的铈硅复合溶胶均可以缓解生菜砷毒害,表现为生菜的地上部鲜重升高了9%～58.8%,砷含量降低了23%～48%。叶面喷施低浓度的二氧化铈掺杂5mmol·L-1二氧化硅复合溶胶可以增加生菜叶片叶绿素含量,进一步提高二氧化硅缓解生菜砷毒害效果。其中以叶面喷施5mmol·L-12%铈掺杂二氧化硅复合溶胶生菜地上部鲜重最高为对照的1.6倍;砷含量最低为对照的51.4%。叶面喷施铈、硅复合溶胶不仅可以降低生菜可食用部位砷浓度,而且可以减少生菜地上部吸收积累砷总量,从而降低了砷通过食物链对人体健康的危害。与传统土壤施用硅肥相比,叶面施用硅溶胶具有经济高效的优点,为土壤砷污染控制提供了一种新的选择。

Foliar application of ceria-silica sol reduced arsenic accumulation in lettuce

The effects of foliar application of ceria,silica or ceria-silica sols on the arsenic（As）accumulation in lettuce grown on As contaminated soil were investigated.The ceria,silica and ceriasilica sols were home-prepared using tetraethyl orthosilicate and ce-rium nitrate by hydrothermal method.The As-polluted soil was collected from Lianhuashan tungsten mine areas.Pot experiments for lettuce culture were conducted to investigate the effects of foliar application of ceria,silica or ceria-silica sols on As accumulation in lettuce.Results showed that foliar application of ceria,silica or ceria-silica sols could alleviate As toxicity.With the different sols foliar application,the fresh weight of lettuce shoots increased about 9%～58.8%while the As concentration in lettuce shoots decreased about 23%～48%,compared with that of control（foliar application of water）.Comparing with silica sol,ceria-silica sol could increase the chlorophyll contents and promote the effects of silica sol on As toxicity alleviation.The optimal molar ratio of ceria and silica was 2%.When 2.0%ceria-silica sol was applied,the fresh weights of lettuce shoots increased up to about 1.6 times while with the As concentration in shoots of lettuce decreased down to about 51.4%of that of the control.Foliar application of ceria-silica sol could not only decrease the As concentration but also reduce As accumulation in lettuce shoots.Comparing with traditional silica soil application,foliar application of silica sol should be more effective and costless.It should be concluded that foliar application silica sol should be an effective method for As risk control for vegetables in As contaminated soil.