Chemical Species of Phosphorus and Zinc in Water‐Dispersible Colloids from Swine Manure Compost

Abstract

The release of phosphorus (P) and zinc (Zn) from swine manure compost and from soils applied with swine manure compost can be accelerated by colloidal particles. This study investigated the concentrations and chemical species of P and Zn in waterdispersible colloids (WDCs) collected from swine manure compost by using X-ray absorption fine structure (XAFS) spectroscopy. A filtration and ultracentrifugation process was used to separate and collect WDCs (20-1000 nm) from the bulk swine manure compost (<2 mm). The swine manure compost contained 2.7 g kg -1 WDC, in which P (140 g kg) was highly concentrated and Zn concentrations were greater than in the bulk compost (1.45 g kg -1). Phosphorus K-edge X-ray absorption near-edge structure (XANES) spectroscopy determined the presence of struvite (NH 4 MgPO 4 ·6H 2 O) as a major P species (74%), followed by tricalcium phosphate as a secondary component (26%). In the WDC fraction, struvite was not found, but tricalcium phosphate (56%) occurred as a primary component. Zinc K-edge XAFS spectroscopy determined hopeite [Zn 3 (PO 4 ) 2 ·4H 2 O, 59%] and to a lesser extent smithsonite (ZnCO 3 , 24%) and Zn adsorbed on ferrihydrite (17%). In the WDC fraction, hopeite (44%) and organically bound Zn (35%) were predominant. Our results demonstrate the notable difference in the concentration and chemical species of P and Zn between the WDC and bulk fractions of swine manure compost. Chemical Species of Phosphorus and Zinc in Water-Dispersible Colloids from Swine Manure CompostKosuke Yamamoto and Yohey Hashimoto* A ccumulation of phosphorus (P) and zinc (Zn) is a concern in agricultural soils where intensive and long-term applications of swine manure are practiced (Martinez and Peu, 2000;Penha et al., 2015). The effluence of P and Zn from swine manure and from soil applied with swine manure can be accelerated by colloidal particles (1-1000 nm in accordance to the International Union of Pure and Applied Chemistry definition) (Slomkowski et al., 2011). Hens and Merckx (2001) reported that P associated with colloidal particles accounts for approximately 75% of effluent P from agricultural soils. Karathanasis (1999) reported that Zn mobility in soils increased 5-to 50-fold in the presence of colloidal particles. Regarding the effects of colloidal particles on bioavailability of elements, Montalvo et al. (2015) demonstrated that colloidal particles increased P bioavailability in a study on P uptake flux by wheat, which accelerated five times in the presence of colloidal P than with dissolved P only. Despite the importance of colloidal fractions in transport and bioavailability, studies have mainly focused on P in particulate and dissolved fractions (operationally defined as a <0.45-mm fraction) and thereby have neglected colloidal fractions in environmental samples.Water-dispersible colloids (WDCs) are representative of readily mobile colloids because of the high dispersibility and mobility in the soil solution (de Jonge et al., 2004). Phosphorus concentrations in WDC fractions (5....

Speciation of Phosphorus Zinc and Copper in Soil and Water-Dispersible Colloid Affected by a Long-Term Application of Swine Manure Compost

“…For instance, SM3 soil (2.4 g kg –1 ) contained two times greater WDC than SM1 soil (1.2 g kg –1 ) (Table S3). A similar amount of WDC was reported in paddy soils (0.8–2.2 g kg –1 , Liang et al), an upland soil (3.8 g kg –1 , Liu et al), and SM compost (2.7 g kg –1 ). The elements consisting of WDC were mainly Si, Al, and Fe for CF soil, and the contribution of C to the constituents of WDC increased notably in the soils treated with continual SM application (Table S3).…”

“…8,9 A notable accumulation of P and Zn was found in the WDC fraction of soil and SM compost compared with those bulk samples. 4,10 With the use of synchrotron-based XAFS spectroscopy, these studies revealed the contrasting differences in chemical species of P and Zn between bulk soil and WDC phases, suggesting the relevance of the WDC fraction for elucidating the mobility and potential bioavailability of elements in soils. Despite the importance of WDC in the transport and bioavailability of elements, previous studies have mainly focused on the bulk soil, particulate, and dissolved fractions (operationally defined as a <0.45 mm fraction) while neglecting colloidal fractions in the soil.…”

“…2 The mobility and potential bioavailability of elements in soils depend on their oxidation states and chemical species. According to previous studies using synchrotoron-based X-ray absorption fine structure (XAFS) spectroscopy, chemical species of elements have been determined in SM and pig slurry mainly as struvite 4 for P, hopeite, 4 Zn phosphate, 5 and ZnS 6 for Zn and Cu associated with organic matter 5 for Cu. It is largely unknown how the chemical species of elements, in particular, Zn and Cu in SM, will have been altered in the soil for a decade or even longer time span.…”

Zinc Speciation in Organic Waste Drives Its Fate in Amended Soils

“…The second Zn species was another form of Zn phosphate: organic Zn phosphate (15% in SS) or crystalline Zn phosphate (8% in PM). Hopeite (crystalline Zn phosphate) has already been documented in previous studies as a major Zn phase in OWs. ,,,, …”

“…Hopeite (crystalline Zn phosphate) has already been documented in previous studies as a major Zn phase in OWs. 15,16,18,22,43 In the present study, the amorphous Zn phosphate reference closely matched the Zn speciation of PM and SS. These findings are in accordance with those of a recent survey of Zn speciation in a large series of OW sampled in full-scale plants 13 where it was reported for the first time that the main Zn species in compost or stockpiled OW was amorphous Zn phosphate (40−100%).…”