Characterization of sedimentary phosphorus in Lake Erie and on-site quantification of internal phosphorus loading.

Lake Erie harmful algal blooms and hypoxia are two major environmental problems, and have severe impacts on human health, aquatic ecosystems, and the economy. However, little is known about internal loading of phosphorus (P) from sediments, which pose a challenge for assessing the efficacy of current conservation measures on the improvement of lake water quality. A modified Hedley's extraction procedure was employed to analyze representative sediment samples collected from the Lake Erie basin for assessing sedimentary P stock, potential availability for release into lake water, and internal P loading. Inorganic and organic P in the sediments were characterized by sequential extractions in H2O, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl, respectively. In the 0 - 10 cm sediment, total P stock was 172, 191, and 170 metric tons km-2 in the western, central, and eastern basins, respectively. Sedimentary P seems unlikely to contribute to internal P loading in the western basin, while in the eastern basin it can potentially contribute to an internal loading of 359 metric tons P yr-1. In the central basin, 41% of organic P, 15% of non-HCl extractable inorganic P, and 9.7% of residual P in the 0 - 10 cm sediment is potentially available for release into lake water; in the 10 - 20 cm sediment, organic P extracted by NaHCO3 and NaOH is also partially available. The central basin potentially contributes to internal P loading at a total amount of 10,599 metric tons yr-1. Internal P loading may not contribute to HABs in the western basin, but it can cause and maintain hypoxia in the central basin and delay the recovery of lake water quality for a lengthy time period in response to external P reduction measures.

Modeling the Impacts of Manure on Phosphorus Loss in Surface Runoff and Subsurface Drainage.

Simulation of phosphorus (P) transfer from manured agricultural lands to water bodies via surface runoff and subsurface drainage is potentially of great help in evaluating the risks and effects of eutrophication under a range of best management practice scenarios. However, it remains a challenge since few models are capable of providing a reasonably accurate prediction of P losses under manure treatment. The Environmental Policy Integrated Climate (EPIC) model was applied to simulate the impacts on dissolved reactive P (DRP) losses through surface runoff and subsurface drainage from a solid cattle manure-amended corn ( L.)-soybean [ (L.) Merr.] rotation on a clay loam soil (Vertisol) located in the Lake Erie region. Simulations of DRP loss in surface runoff and tile drainage were satisfactory; however, EPIC did not consider DRP loss directly from manure, weakening its accuracy in the prediction of DRP loss in surface runoff. Having previously drawn on EPIC-predicted surface runoff to initiate SurPhos (Surface Phosphorus and Runoff Model) predictions of DRP losses strictly in surface runoff, no comparison had been made of differences in manure application impacts on EPIC- or SurPhos-predicted DRP losses-accordingly, this was assessed. The SurPhos improved the estimation of DRP loss in surface runoff (Nash-Sutcliffe coefficient, 0.53), especially when large rain events occurred immediately after or within 6 wk of manure application. Generally, EPIC can capture the impacts of manure application on DRP loss in surface runoff and subsurface drainage; however, coupling of the EPIC and SurPhos models increased the accuracy of simulation of runoff DRP losses.

Solid Cattle Manure Less Prone to Phosphorus Loss in Tile Drainage Water.

Forms (e.g., liquid and solid) of manure influence the risk of P loss after land application. The objective of this study was to investigate the effects of P-based application of various forms of cattle manure (liquid, LCM; or solid, SCM) or inorganic P as triple superphosphate (IP) on soil P losses in tile drainage water. A 4-yr field experiment was conducted in a clay loam soil with a corn ( L.)-soybean [ (L.) Merr.] rotation in the Lake Erie basin. Over the 4 yr, the dissolved reactive P (DRP) flow-weighted mean concentration (FWMC) in tile drainage water was greater under SCM fertilization than under either IP or LCM fertilization. Despite its lower value on an annual basis, DRP FWMC rose dramatically immediately after LCM application. However, the differences in DRP FWMC did not result in detectable differences in DRP loads. Regarding particulate P and total P losses during the 4 yr, they were 68 and 47%, respectively, lower in the soils amended with SCM than in those with IP, whereas both values were similar between IP and LCM treatments. Overall, the P contained in solid cattle manure was less prone to P loss after land application. Accordingly, the present results can provide a basis for manure storage and application of best management practices designed to reduce P losses and improve crop growth.

[Effect of Equisetum hyemale on experimental hyperlipemia in rats and its toxic test].

The results of an experimental study in rats fed with Equisetum hyemale and hyperlipid food have proved that inhibiting effects on the elevation of triglyceride and cholesterol can be obviously observed in both high and low doses of Equisetum. The study also shows that Equisetum hyemale can antagonize the hyperlipemia in rats. The acute toxic test has proved its low toxicity.