腐殖酸对沉积物中纳米银的释放及其毒性的影响研究

以有机质腐殖酸(Humic acid, HA)为例, 研究沉积物中不同HA含量(0、1%、5%和10%)对沉积物其中纳米银(Silver nanoparticles, AgNPs)浓度为100 μg/g dw]中AgNPs释放的影响, 以及银释放对斑马鱼(Danio Rerio)的毒性效应。结果显示, 暴露15d和30d后, 水柱中总银浓度为(0.01±0.01)—(2.53±0.52) μg/L, 且高HA含量(5%和10%)的沉积物组中释放到水柱中的银浓度高于低HA含量(0和1%)的沉积物组, 表明HA的存在促进了沉积物中AgNPs向水柱释放。释放的AgNPs能够积累在斑马鱼组织中, 且主要积累在肝脏和肠道中, 并可导致斑马鱼组织氧化应激效应。另外, 16S rRNA高通量测序结果显示, 受释放到水柱银影响, 斑马鱼肠道中微生物群落结构也会发生改变。研究初步探明了沉积物中AgNPs的释放规律及其环境风险, 可为全面评价AgNPs的环境行为及生态安全性提供重要依据。

THE RELEASE OF SEDIMENT-ASSOCIATED SILVER NANOPARTICLES BY HUMIC ACID AND ITS TOXICITY ON ZEBRAFISH

As an important sink for silver nanoparticles (AgNPs), sediments are also the source of contaminated AgNPs in the aquatic environment, however, there is a serious lack of understanding about the release of AgNPs in sediments and their environmental risks. Natural organic matter (NOM), as an important component of sediments, how to affect the release of AgNPs in sediments is still unclear. This study used humic acid (HA) as NOM to investigate the effect of different HA contents (0, 1%, 5% and 10%) on the release of AgNPs from sediments (AgNPs concentration is 100 μg/g Ag dw) and the toxic effects of released Ag on zebrafish. The results showed that the concentration of total Ag in the water column was (0.01±0.01)—(2.53±0.52) μg/L after 15 and 30 days of exposure, and the released Ag concentration from high HA content group (5% and 10%) was higher than that of low HA content group (0 and 1%), indicating that HA promoted AgNPs release from the sediment. The released AgNPs can accumulate in zebrafish tissues (mainly in the liver and intestine) to cause tissue oxidative stress. Ag also impact the microbial community structure in the zebrafish intestine based on 16S rRNA high-throughput sequencing results. The study proved the release rule of AgNPs in sediments and its environmental risk, which can provide an important basis for comprehensive evaluation of environmental behavior and ecological safety of AgNPs.