Sediment Magnetic Susceptibility and Instream Water
Quality
across
the Coulee Baton Microwatershed in Southwestern Louisiana
Timothy Duex, Sean Comisky, Durga Poudel, and Carl Richter
University of Louisiana at Lafayette, Lafayette, Louisiana 70504
Surface water
quality
impairment of rivers, lakes, and streams and its negative impact
on their designated uses have become one of the major environmental concerns in
recent decades. Although channel contribution to sediments and
water
quality
impairment
in a
water
body is widely acknowledged, information on this issue is scattered and
limited. This study was designed to study the variation in sediment character and instream
surface
water
quality
in a watershed that is primarily agricultural. We identified
seven sites for sediment collection,
water
quality
sampling, and channel characterization
in Coulee Baton microwatershed in southwestern Louisiana. Samples were collected on
a monthly basis for one year. The
water
quality
parameters pH, temperature, turbidity,
conductivity, and dissolved oxygen were measured in the field. Total Suspended Solids
(TSS), Total Combustible Solids (TCS), 5-day Biological Oxygen Demand (BOD5), and
Fecal Coliform (FC) Counts were determined in the lab. Sediment was collected from
three spots at each site (left bank, center of stream, and right bank) and analyzed using
Magnetic Susceptibility as a proxy for pollution. Doppler readings were taken to measure
discharge at the primary drainage outlets of the watershed. Heavy metals and pollutants
apparently are trapped deep in the clay and show a seasonal variation. The TSS
concentration at the main outlet of the watershed is indicates that suspended sediment is
one of the major pollutants in the watershed. Results of FC analyses shows that
water
bodies near residential areas have excessively high FC counts. It is recommended that
appropriate Best Management Practices be implemented for controlling sediment load
and Fecal Coliform pollution in the Coulee Baton microwatershed.
AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012