Partitioning of metals between the aqueous phase and suspended insoluble material in fog droplets
Partitioning of metals between the aqueous phase and suspended insoluble material in fog droplets
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DOI：
10.1002/adic.200590033
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发表时间：
2005-05-01
期刊：
影响因子：
--
通讯作者：
Mangani, F
中科院分区：
文献类型：
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作者：
Mancinelli, V;Decesari, S;Mangani, F
本文讨论了分配的金属（K，Na，Ca，Mg，Al，Cu，Fe，Pb和Zn）之间的水相和悬浮的不溶性物质在雾样品中收集在Po谷在两个广泛的领域运动。金属平均占悬浮不溶性物质质量的11%，而主要成分是碳（有机碳，OC = 35%，黑碳，BC = 8%）。未计算的悬浮物质量非常高，平均为46%，并且可归因于非金属物质，例如O和N以及Si。不溶性悬浮物中的主要金属元素是Fe和Al（2 - 5%），而其它金属元素（Na、Mg、Cu、Pb和Zn）的贡献小于1%。Ca和K的空白值较高，在空白检测限阈值以上无法检出。水相中的主要成分为NO3-（34%）、WSOC（23%）、SO42-（18%）和NH4+（19%），而痕量金属和剩余的阳离子和阴离子占溶质质量的不到1%。雾滴中溶解态微量金属主要为Zn、Al和Fe，金属阳离子主要为Na和Ca。Fe和Al是优先分布在雾滴悬浮不溶物中的两种金属（分配比分别为37%和33%）。所有其他金属大部分溶解在水相中（Mg、Pb、Zn、Cu和Na的平均分配比为69%、70%、77%、81%和87%）。这些发现与文献资料中的金属形态的云和雨样品。分配比对pH值的依赖性进行了研究的不同的金属，只有铝显示出一个明确的分配比随pH值的增加而减少。相反，其他金属显示没有依赖性或复杂的和高度可变的行为。铁的分配比（平均37%），远高于气溶胶颗粒中的水可提取铁（通常为1 - 2%）：这一事实可以用不同地点的气溶胶来源和成分的差异以及水相中的化学过程来解释，例如涉及有机配体的络合和氧化还原反应（草酸盐，或其他有机酸作为腐殖类有机物），其可以促进Fe溶解度。
This paper discusses the partitioning of metals (K, Na, Ca, Mg, Al, Cu, Fe, Pb and Zn) between the aqueous phase and the suspended insoluble material in fog samples collected in the Po Valley during two extensive fields campaigns. Metals represent on average 11% of the mass of suspended insoluble matter, while the main component is carbon (both organic carbon, OC = 35%, and black carbon, BC = 8%). The unaccounted suspended matter mass is very high, on average 46%, and is attributable to non metallic species, such as O and N and of Si. The principal metals in the insoluble suspended fraction are Fe and Al (2-5%), while the contributions of other metals (Na, Mg, Cu, Pb and Zn) are lower than 1%. Ca and K exhibited high blank values and could not be detected above blank detection limit threshold. The main components in the aqueous phase are NO3- (34%), WSOC (23%), SO42-(18%) and NH4+ (19%), while trace metals and remaining cations and anions accounted for less than 1% of solute mass. The main dissolved trace metals in fog droplets are Zn, Al and Fe, while the main metallic cations are Na and Ca. Fe and Al are the only metals preferentially distributed in the suspended insoluble matter of fog droplets (partitioning ratio respectively 37% and 33%). All other metals are mostly dissolved in the aqueous phase (mean partitioning ratios of Mg, Pb, Zn, Cu and Na are 69%, 70%, 77%, 81% and 87%). These findings are in agreement with literature data on metal speciation in cloud and rain samples. The dependence of partitioning ratios on pH is investigated for the different metals, with only Al showing a clear partitioning ratio decrease with increasing pH. Conversely, the other metals show no dependence or a complex and highly variable behaviour. The partitioning ratio of iron (mean 37%) observed in the Po Valley fog samples is much higher than the water extractable iron in aerosol particles (typically 1-2%): this fact can be explained by differences in the aerosol sources and composition among sites and by chemical processes in the aqueous phase, such as complexation and redox reactions involving organic ligands (oxalate, or other organic acids as humic-like organic matter) which may promote Fe solubility.