Assessments of Potential Spatial‐temporal Variations in Phosphorus Distribution and Fractionation in River Bed Sediments

Abstract

Sediment characteristics influence the distribution and bioavailability of phosphorus (P) in river sediments. In this study, we analyzed different P fractions in the sediments of the Bronx River, New York City, NY, using sequential extraction. The results showed that the average P pool rank order was HClÀP > NaOHÀP > NaHCO 3 ÀP > residueÀP, and their relative proportions were 3.7: 2.0: 1.4: 1 in sediments collected in 2006, while HClÀP > NaOHÀP > residueÀP > NaHCO 3 ÀP, with their relative proportions of 27.8:6.2:2.7:1 in the sediments obtained in 2007. The strong correlation between microbial P and organic P (OP), along with the changes in microbial P over time indicate that most of the OP in the river bed sediments is potentially bioavailable. The sediment transport, deposition, assimilation, the exchange of P between sediments and water columns, the land use changes, raw sewer discharge, gas spill, construction, fertilizer application, etc., as well as the hydro-climatic changes could result in the spatial and temporal variations in P bioavailability in the river bed sediments. The estimations of P pools and their bioavailability in river bed sediments could help determine the spatial and temporal variations in P transport and impacts of land use on water quality, in turn, help regulate P in the river's watershed.

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York

“…Original sorbed P-S 0 , P absorption energy K f and bonding strength (k) were highest among 15 sites [27]; S max was the lowest among the 15 sites, relative high EPC 0 values (more than average 0.36 mg·l -1 ), indicating there was high original sorbed P-S 0 in sediments that was correlated with P absorption energy-K f (0.883), constant relates to bonding strength-k (0.569), and sorption coefficient K d (0.796) meanwhile there was low sorption capacity in sediments [27]. Site 4 had the second most negative value of microbial P. Wang and Pant [25] mentioned that the negative values of microbial P were possibly caused by different microorganisms or bacteria which were resistant to cell lysis/inhibition, and they could not be paralyzed by chloroform. Those resistant microorganisms and bacteria continue to proliferate and uptake the SRP/BAP resulting in negative values.…”

“…Sediments were sequential extracted by NaHCO 3 , NaOH, and HCl, and TP was sum of NaHCO 3 -P, NaOH-P, HCl-P and residue-P. The sum of NaHCO 3 -P and NaOH-P was considered as BAP here [6,[23][24][25]. Sediments were hydrolyzed by commercial PDEase and NPase at 37˚C [12].…”

“…Phosphorus sorption characteristics were determined from batch incubation experiments under aerobic conditions [26][27]. Water samples were analyzed for EC, pH, for SRP using ascorbic color metric method [28]; ash TP was determined by persulfate digestion block method [29] for comparison with sum TP, and OP was calculated from the difference between sum TP and SRP [25]. P compounds in sediments were identified by 31 P-NMR.…”

“…Those resistant microorganisms and bacteria continue to proliferate and uptake the SRP/BAP resulting in negative values. The more negative the value, the more resistant microorganism/bacteria biological activities occurred and uptake more P [4,25]. The high negative microbial P at site 4 indicated there were more P microbial available, and enzyme could hydrolyzed those microbial P to SRP for plants use.…”

Enterococci levels in the Bronx River during dry and wet weather conditions

“…(HydroQual Inc., 2001) Several studies have been published on the presence of nutrient pollutants such as nitrogen and phosphorus in the Bronx River. (Wang & Pant, 2011;Hoellein et. al., 2011) Total and fecal coliform concentrations were also reported by the DEP in their Waterbody/Watershed Facility Plan published in 2010.…”