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Seasonal dissolved organic carbon dynamics in estuarine and near-shore waters

机译：河口和近岸水域的季节性溶解有机碳动态

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摘要

Dynamics of dissolved organic carbon (DOC) in near-shore and estuarine environments were examined in Massachusetts Bay and the Pawcatuck River estuary. Both field and laboratory studies were employed to identify important seasonal sources and sinks of DOC in these two ecosystems. Experimental and interlaboratory comparison studies were also conducted to assess the accuracy of the wet chemical oxidation (WCO) technique developed for DOC analyses.;As part of a large environmental monitoring program, DOC and other biological and chemical parameters were measured on 18 cruises conducted from 1992-1994 in Massachusetts and Cape Cod Bays. Regression analyses of DOC and ancillary parameters suggested that major DOC sources changed seasonally in the Bays. In spring months (February-April), surface DOC was negatively correlated with distance$sp{-1}$ from Boston Harbor (r$sp2$ = 0.26, p $<$ 0.0001) and positively correlated with phaeophytins (r$sp2$ = 0.23, p $<$ 0.0001). Together, these two parameters explained 42% of DOC variation and suggested that important spring DOC sources included wastewater-derived inputs entering via Boston Harbor, and in situ production associated with phytoplankton processes. Summer and fall months (June-October) showed a DOC pool associated with undersaturated dissolved oxygen and positively correlated with both ammonium and phosphate (r$sp2$ = 0.61 and 0.46, respectively; p $<$ 0.0001). These strong correlations suggest that microzooplankton grazing activity became an important DOC source during the summer/fall period.;In contrast to Massachusetts Bay, phytoplankton appeared to be the primary DOC source during the summer, dominating DOC dynamics in the Pawcatuck River estuary. Both field transects and incubation studies indicated large autochthonous DOC inputs (6.7-34.7 $mu$mol C liter$sp{-1}$ d$sp{-1}$) which were spatially associated with phytoplankton biomass and positively correlated with DCMU enhanced fluorescence (F$rmsb{DCMU}),$ a proxy for phytoplankton biomass (r$sp2$ = 0.555, p $<$ 0.001). While allochthonous DOC inputs were large, laboratory mixing experiments and field transects suggested that most of the riverine DOC mixed conservatively with only a small fraction ($sim$2-10%) potentially flocculating upon estuarine mixing. However, even the low percentage of flocculation could potentially provide 56 g C m$sp{-2}$ y$sp{-1}$ to the estuarine sediments. Riverine DOC may also indirectly influence DOC dynamics in this system through its control on light attenuation, and hence phytoplankton production in the Pawcatuck system.
机译：在马萨诸塞湾和波卡特卡克河河口研究了近岸和河口环境中溶解有机碳（DOC）的动力学。现场和实验室研究都被用来确定这两个生态系统中重要的季节性DOC来源和汇。还进行了实验和实验室间的比较研究，以评估为DOC分析开发的湿化学氧化（WCO）技术的准确性。作为大型环境监测计划的一部分，在从1986年进行的18次航行中测量了DOC和其他生化参数1992-1994年在马萨诸塞州和科德角湾。 DOC和辅助参数的回归分析表明，海湾地区主要DOC来源季节性变化。在春季（2月至4月），表面DOC与距波士顿港的距离$ sp {-1} $呈负相关（r $ sp2 $ = 0.26，p $ <$ 0.0001），而与Pheophytins呈正相关（r $ sp2 $ = 0.23，p $ <$ 0.0001）。这两个参数共同解释了DOC的42％变化，并表明重要的春季DOC来源包括通过波士顿港进入的废水来源输入以及与浮游植物过程相关的原位生产。夏季和秋季月份（6月至10月）显示DOC池与不饱和溶解氧相关，并且与铵和磷酸盐都呈正相关（r $ sp2 $ = 0.61和0.46； p $ <$ 0.0001）。这些强烈的相关性表明，微浮游动物的放牧活动在夏季/秋季成为重要的DOC来源。与马萨诸塞湾相反，浮游植物似乎是夏季的主要DOC来源，在Pawcatuck河口的DOC动态中起主导作用。田间样面和孵化研究均表明，大量的自生DOC输入（6.7-34.7 $ mu $ mol C升$ sp {-1} $ d $ sp {-1} $）与浮游植物生物量在空间上相关，与DCMU呈正相关荧光（F $ rmsb {DCMU}），是浮游植物生物量的代理（r $ sp2 $ = 0.555，p $ <$ 0.001）。尽管异源DOC的输入量很大，但实验室混合实验和现场样条表明，大多数河道DOC保守地混合在一起，只有一小部分（sim $ 2-10％）在河口混合时可能絮凝。但是，即使絮凝率很低，也可能为河口沉积物提供56 g C m $ sp {-2} $ y $ sp {-1} $。河流DOC还可以通过控制光衰减来间接影响该系统中的DOC动态，从而控制Pawcatuck系统中浮游植物的产量。

著录项

  • 作者

    McKenna, James H.;

  • 作者单位

    University of Rhode Island.;

  • 授予单位 University of Rhode Island.;
  • 学科 Biological oceanography.;Biogeochemistry.
  • 学位 Ph.D.
  • 年度 1996
  • 页码 196 p.
  • 总页数 196
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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