Chemical interaction of atmospheric mineral dust-derived nanoparticles with natural seawater--EPS and sunlight-mediated changes.
Chemical interaction of atmospheric mineral dust-derived nanoparticles with natural seawater--EPS and sunlight-mediated changes.
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DOI：
10.1016/j.scitotenv.2013.08.059
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发表时间：
2014-01
期刊：
影响因子：
--
通讯作者：
E. Kádár;M. Cunliffe;Andrew Fisher;B. Stolpe;J. Lead;Zongbo Shi
中科院分区：
文献类型：
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作者：
E. Kádár;M. Cunliffe;Andrew Fisher;B. Stolpe;J. Lead;Zongbo Shi
实验室研究了在环境相关条件下，通过模拟矿物粉尘与海水的云处理形成的纳米颗粒（NPs）的相互作用。评估了阳光和外聚物（EPS）的存在对以下方面的影响：（1）纳米颗粒聚集体的胶体稳定性（即尺寸分布、ζ电位、多分散性）;（2）微观形态和（3）颗粒中的Fe溶解。我们已经证明：（i）合成纳米水铁矿与由矿物粉尘形成的纳米颗粒具有不同的聚集行为，因为在海水中分散时，平均流体动力学直径保持不变（~ 1500 nm），而所有粉尘衍生的NP的聚集体尺寸增加约三倍;（二）在模拟矿物粉尘的云处理过程中形成的相对稳定和单分散的NP聚集体在接触中变得更加多分散和不稳定海水;（iii）EPS与水铁矿和粉尘衍生的NP两者形成稳定的聚集体，其流体动力学直径在海水中超过24小时保持不变;（iv）来自NP的溶解的Fe浓度，在此测量为< 3 kDa的过滤级分，在EPS存在下在海水中始终高出> 30%，并且在没有光的情况下效果甚至更显著;（v）来自矿物粉尘的纳米颗粒的微观形态与MQ水中的合成水铁矿的微观形态非常相似，但在含有EPS的海水中，它们形成不太致密的聚集体，尺寸变化很大，可能是由于EPS介导的空间和静电相互作用。的EPS增溶效果的Fe和其他金属的胶体稳定性的额外增强的真实的系统上的较大规模的影响进行了讨论。
Laboratory studies were conducted to investigate the interactions of nanoparticles (NPs) formed via simulated cloud processing of mineral dust with seawater under environmentally relevant conditions. The effect of sunlight and the presence of exopolymeric substances (EPS) were assessed on the: (1) colloidal stability of the nanoparticle aggregates (i.e. size distribution, zeta potential, polydispersity); (2) micromorphology and (3) Fe dissolution from particles. We have demonstrated that: (i) synthetic nano-ferrihydrite has distinct aggregation behaviour from NPs formed from mineral dusts in that the average hydrodynamic diameter remained unaltered upon dispersion in seawater (~ 1500 nm), whilst all dust derived NPs increased about three fold in aggregate size; (ii) relatively stable and monodisperse aggregates of NPs formed during simulated cloud processing of mineral dust become more polydisperse and unstable in contact with seawater; (iii) EPS forms stable aggregates with both the ferrihydrite and the dust derived NPs whose hydrodynamic diameter remains unchanged in seawater over 24 h; (iv) dissolved Fe concentration from NPs, measured here as < 3 kDa filter-fraction, is consistently > 30% higher in seawater in the presence of EPS and the effect is even more pronounced in the absence of light; (v) micromorphology of nanoparticles from mineral dusts closely resemble that of synthetic ferrihydrite in MQ water, but in seawater with EPS they form less compact aggregates, highly variable in size, possibly due to EPS-mediated steric and electrostatic interactions. The larger scale implications on real systems of the EPS solubilising effect on Fe and other metals with the additional enhancement of colloidal stability of the resulting aggregates are discussed.