The Biogeochemistry of Hydrogen Sulfide and Carbonyl Sulfidein the Surface Ocean: Production and Consumption Mechanismsand Rates

在含氧海水中，硫化氢以不络合的溶解态存在（“游离硫化物”）。H2S+HS+S2)，作为溶解的金属硫化物配合物（“络合硫化物”），以及作为颗粒金属硫化物。海洋表面硫化物的生物地球化学循环包括海洋-空气交换、与微量金属的反应、通过羰基硫化物（OCS）水解和浮游植物的排放产生，以及通过氧化和颗粒沉降去除。在这种方式下，对OCS和硫化氢的循环的理解与全球硫循环和微量金属的循环有关。研究人员已经开发出了测定微摩尔浓度下OCS和硫化氢形态（未络合/络合；颗粒/溶解）的分析方法，测量了海水中OCS的水解速率，并确定了浮游植物是海洋表面溶解和颗粒硫化氢的重要来源。本研究将量化硫化氢循环的剩余部分，具体目标是：(1)确定与Cd、Ni和Zn的硫化物配合物的形成常数，并在热力学络合模型中使用这些常数来帮助阐明溶解硫化物的化学形态；(2)测定未络合硫化物被碘酸盐氧化的速率；(3)测量浮游植物产生颗粒硫化物的通量；(4)量化浮游植物产生总溶解硫化物和颗粒硫化物的速率；(5)评价有机物颗粒再生过程中是否会产生OCS， OCS是未络合硫化物的前体，是一种重要的辐射气体。

Hydrogen sulfide in oxic seawater can be found as uncomplexed dissolved species ("free sulfide. H2S+HS+S2), as dissolved metal sulfide complexes ("complexed sulfide"), and as particulate metal sulfides. The biogeochemical cycle of sulfide species in the surface ocean includes sea-air exchange, reactions with trace metals, production via carbonyl sulfide (OCS) hydrolysis and emissions from phytoplankton, and removal via oxidation and particle sinking. In this fashion, an understanding of the cycling of OCS and hydrogen sulfide species is relevant to the global sulfur cycle and to the cycling of trace metals. Analytical methods have been developed to determine OCS and hydrogen sulfide speciation (uncomplexed/complexed; particulate/dissolved) at picomolar concentrations, the rate of OCS hydrolysis in seawater has been measured, and phytoplankton has been identified as important sources of dissolved and particulate sulfide in the surface ocean. This research will quantify the remaining portions of the hydrogen sulfide cycle, with the specific objectives being (1) to determine the formation constants of sulfide complexes with Cd, Ni, and Zn, and use these in thermodynamic complexation models to help elucidate the chemical speciation of dissolved sulfide; (2) to determine the rate of oxidation of uncomplexed sulfide by iodate; (3) to measure the flux of particulate sulfide production by phytoplankton; (4) to quantify the rates of total dissolved and particulate sulfide production by phytoplankton; (5) to evaluate whether OCS, a precursor of uncomplexed sulfide and a radiatively important gas, can be produced during the regeneration of particulate organic matter.