Suspended soil as a source of potentially bioavailable phosphorus in surface runoff waters from clay soils

• Published in: Water research (Oxford) 2000-06, Vol.34 (9), p.2477-2482
• Main Authors: Uusitalo, Risto, Yli-Halla, Markku, Turtola, Eila
• Format: Article
• Language: English
• Subjects: anion exchange resin; Applied sciences; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; erosion control; eutrophication; Exact sciences and technology; Finland; Freshwater; Hydrogeology; Hydrology. Hydrogeology; Natural water pollution; phosphorus fractions; Pollution; Pollution, environment geology; Rainwaters, run off water and others; runoff; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(99)00419-4

The contribution of suspended soil as a source of potentially bioavailable P in runoff water was investigated by anion exchange resin (AER) extraction. The samples were also analysed for total P (TP) and dissolved reactive P (DRP). Particulate P (PP) was calculated by subtracting DRP from TP, and reversibly adsorbed particulate P (PPi) by subtracting DRP from AER-P. The material consisted of 154 surface runoff samples, collected from four arable clay soils in southern Finland. Total P and PPi correlated closely with TSS, but DRP did not. When the TSS concentration increased, the increasing proportion of AER-P consisted of PPi. In runoff low in TSS (0.2–0.5 g l −1), PPi constituted 12–23% of AER-P; the dominant fraction (77–88%) of AER-P being DRP. When the TSS concentration increased, PPi became an important contributor to potentially bioavailable P, accounting for 35–69% of AER-P when TSS was 1.0–2.5 g l −1. The average amount of PPi in suspended soil material ranged from 39 to 165 mg kg −1 at different sites, depending on soil P status. If PPi is not taken into account, P bioavailability in turbid runoff may be severely underestimated.