土壤中红霉素结合残留在菜心中生物有效性研究

Bioavailability of the Bound Residues of ^14C-erythromycin in Soil

为探究土壤环境中红霉素污染的生物风险,本试验采用14C示踪技术,选取广东菜心为代表,研究红霉素结合残留的释放、转化及生物有效性,并探讨添加外源有机肥(如鸡粪、活性淤泥)对该过程的影响。结果表明,土壤中红霉素结合残留随着时间推移逐渐释放,在培养45 d时下降至引入量的59.83%,其中15.00%转化为可提态残留;植物根系的吸收和扰动能促进红霉素结合残留的释放和转化(P<0.05);土壤中的红霉素结合残留能够被广东菜心根部吸收并转运至可食部分,转运系数为0.34,表明红霉素结合残留在菜心体内不易向上运输;放射性自显影图片显示,被植物吸收的14C-红霉素及其放射性衍生物主要集中在叶片和根部;外源添加有机肥(鸡粪和活性淤泥)处理,一方面可抑制结合残留的释放,增加富啡酸中红霉素结合残留的含量(P<0.05),导致土壤中红霉素污染更持久,另一方面可促进植物对土壤中红霉素残留的吸收;腐殖质分级结果显示,红霉素结合残留主要集中在富啡酸中(87.92%~97.21%),并随着时间推移不断释放。本研究结果为科学评价红霉素的生态安全提供了理论支持。

In order to explore the biological risks of erythromycin in soil, Chinese Flowering Cabbage was used for studying the release, transformation and bioavailability of erythromycin bound residues(BR) in soil by 14C tracing. The effects of two organic fertilizers, such as chicken manure and biosolid on the process were also discussed. Results showed that after incubation for 45 days, the bound residues were decreased to 59.83% of initial amount, among which about 15.00% were converted to extractable residues. The absorption and disturbance of plant roots can promote the transformation of bound residues(P<0.05). The bound residues of 14C-erythromycin in soil were bioavailable and could be absorbed by the Flowering Chinese Cabbage, and then transported to its edible parts with a transport coefficient of 0.34. Autoradiography results showed that 14C-erythromycin bound residues absorbed by the plant were mainly distributed in leaves and roots. The amendment of organic fertilizers such as chicken manure and biosolid could slow down the release of the bound residues and increase the content of binding residues in fulvic acid(P<0.05), resulting in longer persistent of erythromycin contamination in the soil, it can promote the uptake of 14C-erythromycin into cabbage at the same time. Fractionation of humic acids showed that bound residues of 14C-erythromycin were mainly distributed in soil fulvic acid(87.92%-97.21%), and was released continuously with time. The addition of organic fertilizers increased the contents of binding residues in fulvic acid. It is of great significance for evaluating the ecological safety of erythromycin in soil.