Abstract: A Study of Heavy Metal Partitioning in Bottom Sediments of Bayou Trepagnier, LA

Timothy D. Dore, Alan M. Bailey

To assess potential impact of metals on the biosphere in bottom sediments, forms were determined for selected metals in a southeastern Louisiana bayou. Sequential extractions provided data on the following phases: (1) an interstitial (pore) water phase, (2) an exchangeable phase, (3) an easily reducible phase, (4) an organic/carbonate phase, (5) a moderately reducible phase, and (6) a residual (structural) phase. Data from the top, middle, and bottom of one meter cores at ten sites allowed variation with depth and distance along the bayou to be studied.

Differences were found to exist between concentrations: from the different levels of extraction; for example, highest concentrations of lead, chromium, and zinc were released during extraction of the organic phase. Higher levels of iron and copper were sometimes released during extraction of other phases. There is also a rough variation of metal concentrations with core depth. On a whole sediment basis, organic-related concentrations were highest for lead in the bottom sections, and were higher for copper, chromium, and zinc in the middle and upper sections. In addition, rough concentration gradients occur along the length of the bayou from the upper reaches to the mouth. Towards the mouth of the bayou, there appears to be little difference between concentrations of these metals and c ncentrations at a control site outside the bayou.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas