Effect of Hurricane Katrina on the Water Quality of the Pearl River (Mississippi)

Unusual events can account for a disproportionate share of elemental transport in fluvial systems. On August 29, 2005, Hurricane Katrina followed a path up the Pearl River valley in Mississippi, leaving a path of considerable destruction of vegetation for a significant distance from the coast. This might enhance fluxes of various dissolved and particulate constituents affected by decaying vegetation (e.g., nutrients, DOC, organically-complexed metals). Fortuitously, we had recently completed a two-year time series of dissolved nutrients, metals, plant pigments, DOC, as well as suspended load and particulate organic matter in the Lower Pearl River in 2001-2003, thereby providing a baseline for comparison. Subsequent to Hurricane Katrina we have been collecting and preserving bi-weekly samples for metals, nutrients, suspended load, particular organic matter, and UV absorbance. This post-storm time series began roughly two months after the storm; however, because of generally dry conditions it seems unlikely that we missed a significant pulse of dissolved material. Although sample collections are continuing, preliminary results indicate no significant change in dissolved concentrations of the Lower Pearl River in the past year. Probably, dry conditions during much of the past year have resulted in only slow decay of woody storm debris and hence the limited effect on water quality.