Biogeochemical behavior of organic carbon in the Trinity River downstream of a large reservoir lake in Texas, USA.
Biogeochemical behavior of organic carbon in the Trinity River downstream of a large reservoir lake in Texas, USA.
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DOI：
10.1016/j.scitotenv.2004.02.017
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发表时间：
2004-08
期刊：
影响因子：
--
通讯作者：
Kent W. Warnken;P. Santschi
中科院分区：
文献类型：
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作者：
Kent W. Warnken;P. Santschi
2000-2001年期间，对位于美国德克萨斯州墨西哥湾上游的加尔维斯顿湾的主要淡水输入源Trinity河进行了溶解态和颗粒态有机碳浓度的测量和年负荷估算。这条河流经一个相对较大的水库湖利文斯顿以南的森林低地。溶解有机碳（DOC）和QTR之间的弱关系表示水文控制，但分离的数据，根据个别放电事件，是必要的，以提高解释。例如，本赛季的第一场雨导致DOC浓度只有适度的增加，并导致与排放量的反比关系，由于减少横向流动和增加雨水的渗透，与较低的流量更有效的DOC从土壤中沥滤。相反，长时间的高流量洪峰事件导致相反的趋势，即DOC随流量增加而线性增加。短时间高排放的热带风暴表明，减少Trinity河DOC浓度和最高的POC浓度测量，可能是由于相对较短的持续时间，最小的接触时间，这一事件。与DOC相反，颗粒有机碳的浓度，POC（mg C l−1）与悬浮颗粒物（SPM）浓度呈线性相关，并在低排放时占总悬浮负荷的10%至12%，但在高排放时下降至20%。这表明稀释较大的颗粒与减少有机碳含量，可能是硅酸盐矿物，更容易再悬浮在排放水平升高。根据日负荷与流量关系的斜率估算出加尔维斯顿湾的年总有机碳（TOC）负荷为11.2× 1010 g C，计算出的输出系数（g C m− 2 year −1）与前人的结果吻合较好。使用这种关系，TOC通量输入到加尔维斯顿湾在过去的四分之一个世纪，并在未来的准确评估是可能的，通过获得年度Trinity河排放率，这是很容易从美国地质勘探局。比较DOC河流输入的底栖来源在Trinity湾，直接测量在同一天，表明沉积物贡献约20%的DOC总输入到Trinity湾。然而，假设在低流量条件下（在德克萨斯州的这一地区可能长达14个月），底栖生物来源不变，则底栖生物通量将占Trinity湾总输入量的80%以上。在高水平的排放量，Trinity河排放量为1.0× 109 g C day-1，并主导了Trinity湾的DOC输入。
Dissolved and particulate organic carbon concentrations were measured and annual loads estimated for the Trinity River, the main freshwater input source to Galveston Bay, which lies on the upper Gulf coast of Texas, USA, during 2000–2001. This river drains the forested lowlands south of a relatively large reservoir lake, Lake Livingston. A weak relationship between dissolved organic carbon (DOC) and QTRindicated hydrologic control but separation of the data, based on individual discharge events, was necessary to improve interpretation. For instance, the first rain of the season resulted in only a modest increase in DOC concentrations and led to an inverse relationship with discharge, due to decreased lateral flow and increased infiltration of rainwater, with the lower flows being more efficient at DOC leaching from soils. In contrast, a long duration high discharge river crest event resulted in an opposite trend, i.e. a linear increase in DOC with increasing discharge rates. A short duration high discharge tropical storm showed reduced Trinity River DOC concentrations and the highest POC concentrations measured, likely resulting from the relatively short duration, and minimal contact time, of this event. In contrast to DOC, the concentrations of particulate organic carbon, POC (mg C l−1) were linearly correlated to suspended particulate matter (SPM) concentrations and accounted for between 10 and 12% of the total suspended load at low discharge but decreased to ∼2% at high discharge. This suggests dilution by larger particles with a reduced organic carbon content, possibly silicate minerals, more readily resuspended at elevated levels of discharge. The annual total organic carbon (TOC) load to Galveston Bay, estimated from the slope of the daily load vs. discharge relationship, was 11.2×1010g C and calculated export coefficients (g C m−2year−1) were in good agreement with previous results. Using this relationship, accurate assessments of TOC flux inputs to Galveston Bay over the past quarter-century and in the future are possible by obtaining annual Trinity River discharge rates, which are readily available from the USGS. Comparing DOC riverine inputs to benthic sources in Trinity Bay, measured directly on the same day, indicates that the sediments contribute approximately 20% of total inputs of DOC to Trinity Bay. However, assuming a constant benthic source during low-flow conditions, which can occur for periods of up to 14 months in this region of Texas, benthic fluxes would account for >80% of the total inputs into Trinity Bay. At high levels of discharge, the Trinity River discharges ∼1.0×109g C day−1and dominates DOC inputs to Trinity Bay.