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ARS Home » Southeast Area » Fayetteville, Arkansas » Poultry Production and Product Safety Research » Research » Publications at this Location » Publication #157089
Title: PHOSPHATE EQUILIBRIUM BETWEEN STREAM SEDIMENTS AND WATER: POTENTIAL EFFECTS OF CHEMICAL AMENDMENTS.

Author
item Haggard, Brian
item EKKA, SUJIT - BAEG - UNIV OF ARKANSAS
item MATLOCK, MARTY - BAEG - UNIV OF ARKANSAS
item CHAUBEY, INDRAJEET - BAEG - UNIV OF ARKANSAS

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2004
Publication Date: 7/1/2004
Citation: Haggard, B.E., Ekka, S.A., Matlock, M.D., Chaubey, I. 2004. Phosphate equilibrium between stream sediments and water: Potential effects of chemical amendments. Transactions of the ASAE. 47(4):1113-1118.

Interpretive Summary: In the Ozark Plateaus, the focus of watershed mangers is often on diffuse sources of phosphorus (P). However, it has become apparent that this shift in focus may be premature and neglect P from the end of pipes, e.g. wastewater treatment plants (WWTPs). Several studies have reported exponential declines in P concentrations downstream of WWTPs and suggested net P uptake lengths are several kilometers at these enriched systems. The sediments at these systems may represent a considerable transient storage pool of P; lengthening the time required to see marked improvements in water-quality. We sampled sediments and the water column at three streams in the Illinois River Basin that receive effluent from municipal WWTPs; these WWTPs represented 45% of annual P load (208,000 kg) from 1997 through 2001. Sediment extractions included equilibrium P concentration (EPC), exchangeable P (ExP) and P sorption index (PSI). Water column P concentrations suggested several kilometers were required to retain about 63% of WWTP inputs. Phosphorus buffering capacity (PSI) was significantly decreased downstream of WWTPs whereas EPC and ExP significantly increased. Alum and calcium carbonate treatment of benthic sediments significantly increased P buffering capacity and reduced ExP and EPC in WWTP impacted streams, but the effect was somewhat relative to WWTP P additions.

Technical Abstract: Sediments often play an important role in the temporary storage and release of phosphorus (P) in streams, especially streams receiving municipal wastewater treatment plant (WWTP) effluent. The objective of this study was to evaluate net retention of WWTP nutrient inputs and sediment-aqueous phase P equilibrium in four Ozark streams, and to determine the effect of chemical amendments [alum (Al2(SO4)3) and calcium carbonate (CaCO3)] on stream sediment-P interactions. Effluent from the WWTPs significantly affected stream nutrient concentrations and physicochemical properties; of particular interest to this study, the increase in P concentrations varied greatly between streams. After dilution corrections, stream water P concentrations showed no significant reduction with increasing distance from the WWTPs at all streams. Phosphorus inputs from WWTP significantly increased sediment equilibrium P concentrations (EPC0) and readily exchangeable sediment-bound P, while decreasing the P buffering capacity of stream sediments. Sediment EPC0 were as great as 7 mg L-1 downstream from one WWTP suggesting sediments are a transient storage pool of P and may release P back into the stream system when P inputs from the WWTP are reduced. However, chemical amendments significantly reduced the sediment EPC0 and readily exchangeable P, while increasing the ability of sediment to buffer increasing P loads.