Intermittent rainstorms cause pulses of nitrogen, phosphorus, and copper in leachate from compost in bioretention systems.

Bioretention systems rely on vegetation and mixtures of soil, sand, and compost to filter stormwater runoff. However, bioretention systems can also leach metals and nutrients, and compost may be a major contributor to this leaching. To safely implement bioretention systems, it is crucial to determine the composition of compost leachate. We characterized and quantified the leachate composition of compost following intermittent, simulated storm events. Columns of municipal compost were irrigated to simulate 6-month, 24-hour rain storms in the Seattle-Tacoma region. Outflow was analyzed for pH, electrical conductivity (EC), particulate concentration, surface tension, dissolved organic carbon (DOC), nitrogen, phosphorus, and copper. Results indicate a decrease of chemical concentrations over the course of individual storms and following repeated storms, but each new storm released another peak of constituents. The decrease in phosphorus, copper, and DOC concentrations with repeated storms was slower than for nitrate and EC. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) showed that the DOC consisted mainly of aliphatic and aromatic components typical of fulvic and humic acids. Less than 3% of the original copper content from the compost leached out even after nine storm events. Nonetheless, copper concentrations in the leachate exceeded regulatory discharge standards. Our results show that compost can serve as a sustained source of leaching of nutrients and metals.

Effect of biochar on leaching of organic carbon, nitrogen, and phosphorus from compost in bioretention systems.

Compost is used in bioretention systems to improve soil quality, water infiltration, and retention of contaminants. However, compost contains dissolved organic matter, nitrate, and phosphorus, all of which can leach out and potentially contaminate ground and surface waters. To reduce the leaching of nutrients and dissolved organic matter from compost, biochar may be mixed into the bioretention systems. Our objective was to test whether biochar and co-composted biochar mixed into mature compost can reduce the leaching of organic carbon, nitrogen, and phosphorus. There was no significant difference between the effects of biochar and co-composted biochar amendments on nutrient leaching. Further, biochar amendments did not significantly reduce the leaching of dissolved organic carbon, nitrate, and phosphorus as compared to the compost only treatment. The compost-sand mix was the most effective in reducing nitrate and phosphorus leaching among the media.

1,1-Diphenyl,2-picrylhydrazyl free radical scavenging, bactericidal, fungicidal and leishmanicidal properties of Teucrium stocksianum.

In the present study, we evaluated the pharmacological and toxicological effects of Teucrium stocksianum. The crude extract of T. stocksianum (Ts.Cr) and its subsequent organic fractions: n-hexane (Ts.Hex), chloroform (Ts.CHCl3) and ethyl acetate (Ts.EtAc) exhibited 1,1-diphenyl,2-picrylhydrazyl free radical scavenging activity with different potencies. Ts.EtAc was found to be most potent. Ts.Cr, Ts.Hex, Ts.CHCl3 and Ts.EtAc showed significant bactericidal activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, Shigella flexneri and Bacillus subtilis at their extent. Ts.Cr, Ts.Hex, Ts.CHCl3 and Ts.EtAc displayed fungicidal action against Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus and Fusarium solani at various minimum inhibitory concentrations. Ts.Cr and Ts.EtAc exhibited marked inhibition of Leishmania tropica growth, observed after 48 and 96 hrs of treatment. These data indicate that the T. stocksianum methanolic extract and its resultant fractions possess antioxidant, antibacterial, antifungal and antileishmanial activities. Thus, the present research unearths the scientific base for T. stocksianum medicinal application as antioxidant and antimicrobial agents.