کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4532403 1626168 2012 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dissolved and colloidal trace elements in the Mississippi River delta outflow after Hurricanes Katrina and Rita
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
پیش نمایش صفحه اول مقاله
Dissolved and colloidal trace elements in the Mississippi River delta outflow after Hurricanes Katrina and Rita
چکیده انگلیسی

The Mississippi River delta outflow region is periodically disturbed by tropical weather systems including major hurricanes, which can terminate seasonal bottom water hypoxia and cause the resuspension of shelf bottom sediments which could result in the injection of trace elements into the water column. In the summer of 2005, Hurricanes Katrina and Rita passed over the Louisiana Shelf within a month of each other. Three weeks after Rita, we collected water samples in the Mississippi River delta outflow, examining the distributions of trace elements to study the effect of Hurricanes Katrina and Rita. We observed limited stratification on the shelf and bottom waters that were no longer hypoxic. This resulted, for instance, in bottom water dissolved Mn being lower than is typically observed during hypoxia, but with concentrations still compatible with Mn–O2 trends previously reported. Interestingly, for no element were we able to identify an obvious effect of sediment resuspension on its distribution. In general, elemental distributions were compatible with previous observations in the Mississippi outflow system. Co and Re, which have not been reported for this system previously, showed behavior consistent with other systems: input for Co likely from desorption and conservative mixing for Re. For Cs, an element for which there is little information regarding its estuarine behavior, conservative mixing was also observed. Our filtration method, which allowed us to distinguish the dissolved (<0.02 μm) from colloidal (0.02–0.45 μm) phase, revealed significant colloidal fractions for Fe and Zn, only. For Fe, the colloidal phase was the dominant fraction and was rapidly removed at low salinity. Dissolved Fe, in contrast, persisted out to mid-salinities, being removed in a similar fashion to nitrate. This ability to distinguish the smaller Fe (likely dominantly organically complexed) from larger colloidal suspensates may be useful in better interpreting the bioavailablity of the Fe in estuarine systems.

\Figure optionsDownload as PowerPoint slideHighlights
► The 2005 hurricanes resuspended shelf sediments and terminated shelf hypoxia.
► Dissolved trace element distributions were compatible with a well-mixed, oxic water column.
► No effects on dissolved trace elements attributable to sediment resuspension were observed.
► Rapid, low S colloidal Fe removal contrasts with slower removal of dissolved Fe.
► Co and Re reported for a 1st time in this system are compatible with other estuaries.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Continental Shelf Research - Volume 42, 1 July 2012, Pages 1–9
نویسندگان
, , ,