Impact of Water Temperature and Dissolved Oxygen on Copper Cycling in an Urban Estuary

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• 作者：Aaron J. Beck ; Sergio A. Sañ ; udo-Wilhelmy
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：September 1, 2007
• 年：2007
• 卷：41
• 期：17
• 页码：6103 - 6108
• 全文大小：164K
• 年卷期：v.41,no.17(September 1, 2007)
• ISSN：1520-5851

文摘

An increasing body of evidence suggests that much ofthe trace metal contamination observed in coastal watersis no longer derived from point-source inputs, but insteadoriginates from diffuse, non-point sources. Previous researchhas shown that water temperature and dissolved oxygenregulate non-point source processes such as sedimentdiagenesis; however, limited information is available regardingthe effect of these variables on toxic trace metal cyclingand speciation in natural waters. Here, we present data onthe seasonal variation of dissolved Cu cycling in theLong Island Sound, an urban estuary adjacent to NewYork City. An operationally defined chemical speciationtechnique based on kinetic lability and organic complexationhas been applied to examine the most ecologicallyrelevant metal fraction. In contrast to the decrease fromspring to summer observed in the total dissolved Cu pool(average ± SD: 15.1 ± 4.4 nM in spring and 11.8 ± 3.5nM in summer), our results revealed that in the highly impactedwestern LIS, levels of labile Cu reached higher levels insummer (range 3.6-7.7 nM) than in spring (range 1.5-3.9 nM). Labile Cu in surface waters of the western Soundappeared to have a wastewater source during springhigh flow conditions, coinciding with elevated levels ofsewage-derived Ag. Labile Cu elsewhere in the LIS duringspring apparently resulted from fluvial input and mixing.During summer, labile Cu increased in bottom waters (at onesite, bottom water labile Cu increased from 1.5 nM inspring to 7.7 nM in summer), and covariance with tracersof diagenetic remobilization (e.g., Mn) revealed asedimentary source. Although total dissolved Cu showedno consistent trends with water quality parameters, labile Cuin bottom waters showed an inverse correlation withdissolved oxygen and a positive, exponential correlationwith water temperature. These results suggest that futureincreases in coastal water temperatures may cause thebenthic source of labile Cu to become proportionally moresignificant.