Arsenic Speciation and Seasonal Changes in Nutrient Availability and Micro-plankton Abundance in Southampton Water, U.K.
Arsenic Speciation and Seasonal Changes in Nutrient Availability and Micro-plankton Abundance in Southampton Water, U.K.
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DOI：
10.1006/ecss.1995.0030
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发表时间：
1995-04
影响因子：
2.8
通讯作者：
A. Howard;S. Comber;D. Kifle;E. Antai;D. Purdie
中科院分区：
文献类型：
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作者：
A. Howard;S. Comber;D. Kifle;E. Antai;D. Purdie
摘要通过对英国南安普顿水体的季节性调查，研究了溶解态砷形态、生物活性与氮磷植物营养素有效性之间的关系。南安普顿水（英语：Southampton Water）（英格兰南部汉普郡）是索伦特河向西北延伸的一段长约10公里、宽约2公里的水域，接受来自Test河和Itchen河的水。它是一个部分混合的河口，东侧是宽阔的潮间带泥滩，有卵石和沙子，西侧是盐沼。选择了两个地点：NW内特利浮标位于受保护的高盐度河口环境中，而Calshot浮标位于南安普顿水域外，处于盐度变化较小的更暴露位置。砷（III）生产在这两个网站的第一个证据发生在4月下旬，在一个主要的中肋骨条藻硅藻水华的衰变。砷（III）的水平上升，作为Aesthetonema取代了一个数字较小，但更多的叶绿素丰富的另一种硅藻，Rattlesolenia delicatula绽放。因此，管螺可能是砷（III）的来源。甲基化砷在水温较低时和硅藻水华初期不存在，而在一周后硅藻水华后期的生长阶段不存在。delicatula，他们变得可检测。甲基化砷水平逐渐增加，通过春季到一个广泛的最大覆盖仲夏，当中缢虫红色，斯氏锥状和相关的微鞭毛虫也达到顶峰。没有随后的单一生物可以链接到释放甲基化砷到南安普顿水;有机砷已被观察到的鞭毛虫，硅藻和纤毛虫的存在。在S. trochoidea和M.但来自内特利的天然细菌的实验室培养实验未能产生任何砷物种浓度的显著变化。磷酸盐耗竭似乎不是砷酸盐同化的先决条件。从夏季高峰甲基化砷的水平，然后逐渐减少到检测不到的水平，在冬季的几个月。一甲基砷，目前的浓度约为50%的二甲基砷，持续时间较长，整个夏天。因此，可以使用氢化物程序测量的砷物质可能代表生物砷化合物分解的中间体，例如砷糖，其被释放，或者作为排泄/分泌产物被主动释放，或者作为衰变过程的一部分被被动释放。目前尚未确定的前体的可氧化还原的砷物种（“隐藏”砷）可以解释的不良联系之间的反渗透活动和可测量的砷物种在水柱中的水平。
Abstract The links between dissolved arsenic speciation, biological activity and the availabilities of the nitrogen and phosphorus plant nutrients have been investigated in a seasonal survey of Southampton Water (U.K.). Southampton Water (Hampshire, southern England) is an approximately 10 km long, and 2 km wide north-westerly extension of the Solent, receiving water from the rivers Test and Itchen. It is a partially mixed estuary bordered by broad intertidal mudflats with shingle and sand on the eastern side, and a salt marsh to the west. Two sites were chosen: NW Netley Buoy is in a sheltered high-salinity estuarine environment whilst Calshot Buoy lies just outside Southampton Water and in a more exposed location of less-variable salinity. The first evidence of arsenic(III) production at both sites occurred in the second half of April, during the decay of a major Skeletonema costatum diatom bloom. Arsenic(III) levels rose as Skeletonema was replaced by a numerically smaller but more chlorophyll-rich bloom of another diatom, Rhizosolenia delicatula. Rhizosolenia is therefore implicated as a possible source of arsenic(III). Methylated arsenic was absent whilst the water temperature was low and during the initial Skeletonema bloom, but a week later, during the growth phase of the succeeding bloom of the diatom R. delicatula , they became detectable. Methylated arsenic levels gradually increased through the spring to a broad maximum covering the mid-summer, when Mesodinium rubrum , Scrippsiella trochoidea and associated microflagellates also peaked. No subsequent single organism could be linked to the release of methylated arsenic into Southampton Water; organoarsenicals having been observed in the presence of flagellates, diatoms and ciliates. A large bacterial maximum was observed following blooms of S. trochoidea and M. rubrum but laboratory culture experiments of natural bacteria from Netley failed to produce significant changes in the concentration of any arsenic species. Phosphate depletion did not appear to be a prerequisite for arsenate assimilation. From the summer peak methylated arsenic levels then gradually diminished to undetectable levels in the winter months. Monomethylarsenic, present at concentrations approximately 50% those of dimethylarsenic, persisted longer through the summer. The arsenic species which can be measured using the hydride procedure may therefore represent intermediates in the decomposition of the bioarsenicals, such as arsenosugars, which are released, either actively as excretion/secretion products or passively as part of the decay process. Currently unidentified precursors of hydride-reducible arsenic species (‘ hidden ’ arsenic) may explain the poor link between planktonic activity and the levels of measurable arsenic species in the water column.