Effects of pretreatment on the sequential phosphorus fractionation of anaerobic sediment

Abstract

Phosphorus (P) fractionation is critical to understand P cycling in sediment and across the sediment-water interface. To examine the effect of pretreatment on the P fractionation of anaerobic sediment, anaerobic sediment samples were treated by oven-drying, airdrying, and freeze-drying, and a fresh sediment sample was used as a control treatment. A five-step sequential extraction procedure was applied, and six P fractions were examined. The results indicated that P NaCl (P extracted by NaCl), P BD (P extracted by Na 2 S 2 O 4 and NaHCO 3 ), P NaOH (P extracted by NaOH), and organic P were significantly influenced by pretreatment, whereas P HCl (P extracted by HCl) and residual P were not significantly affected by pretreatment. Compared to fresh sediment, drying treatments decreased P NaCl , P NaOH , and organic P but increased P BD . Among the three drying methods, oven-drying resulted in the greatest change in P fractionation; the effects of air-drying and freeze-drying were similar to each other. The total extracted P were similar among the four pretreatment methods. For the measurement of accurate P fractions, fresh sediment is the best option.

An innovative approach for sequential extraction of phosphorus in sediments: Ferrous iron P as an independent P fraction

“…Conversely, mean CDB-P content significantly increased from 187.1 to 280.7 mg/kg DW. For other P fractions, O-P remained constant, Ca-P significantly decreased, and loosely-bound P significantly increased (P<0.05, n ¼ 9), which is consistent with previous results (Lukkari et al, 2007a,b;Kraal et al, 2009;Zhang et al, 2013Zhang et al, , 2014. Kraal et al (2009) concluded that P fractionation in anoxic, carbonate-poor sediments is strongly affected by pyrite oxidation that occurs when these sediments are exposed to oxygen; pyrite oxidation produces sulfuric acid and iron oxyhydroxides.…”

Forms of Nutrients in Rivers Flowing into Lake Chaohu: A Comparison between Urban and Rural Rivers

“…These traits made NaCl-P more likely to be found at greater levels in the urban rivers than in the rural rivers, in terms of both the content and percentage of P (Figure 6), although no significant differences were identified between the two groups. HCl-P mainly corresponds to P bound to carbonates and apatite-P [33]. HCl-P is typically determined by the geology and geochemistry of the studied basin and generally mirrors the characteristics of the basin.…”

“…The elevated levels of TP in surface sediment of the urban rivers were attributed to rise in BD-P and NaOH-P ( Figure 6). Both of these fractions correspond to metal-bound P. Specifically, BD-P, also called Fe-P, is a redox-sensitive form of P bound to reducible Fe and Mn oxides, and NaOH-P correspond to P bound to Al oxides and non-reducible Fe oxides [25,33]. Fe-P is positively correlated with TP and SRP in water [34], and higher levels of Fe-P have been detected in more heavily polluted sediments [35].…”