No abstract

Phosphorus (P) eutrophication is a major pollution problem globally, with unprecedented amount of P emanating from agricultural sources. But little is known about the optimization of soil-biochar P sorption capacity. The study objective was to determine how biochar feedstocks and pyrolysis conditions influences carbon (C) thermal stability, C composition and pH and in turn influence the phosphorus sorption optimization. Biochar was produced from switchgrass, kudzu and Chinese tallow at 200, 300, 400, 500, 550, 650,750 °C. Carbon thermal stability was determined by multi-element scanning thermal analysis (MESTA), C composition was determined using solid state C NMR. Phosphorus sorption was determined using a mixture of 10% biochar and 90% sandy soil after incubation. Results indicate increased P sorption (P< 0.0001) and decreased P availability (P < 0.0001) with increasing biochar pyrolysis temperature. However, optimum P sorption was feedstock specific with switchgrass indicating P desorption between 200 and 550 °C. Phosphorus sorption was in the order of kudzu > switchgrass > Chinese tallow. Total C, C thermal stability, aromatic C and alkalinity increased with elevated pyrolysis temperature. Biochar alkalinity favored P sorption. There was a positive relationship between high thermal stable C and P sorption for Kudzu (r = 0.62; P = 0.0346) and Chinese tallow (r = 0.73; P = 0.0138). In conclusion, biochar has potential for P eutrophication mitigation, however, optimum biochar pyrolysis temperature for P sorption is feedstock specific and in some cases might be out of 300-500 °C temperature range commonly used for agronomic application. High thermal stable C dominated by aromatic C and alkaline pH seem to favor P sorption.

The reaction of Fe(III) and ascorbic acid (AA) in food products and digestive tracts affects the efficiency and uptake of these two nutrients. We investigated the kinetics of Fe(III) reduction by AA at pH 5 and 6 in a model system at 25 degrees C. The results indicate that the reduction of Fe(III) by AA is of zero order with respect to AA. The reaction order with respect to Fe(III) cannot be represented by a simple kinetic model at pH 5 or 6. The major stage of the reduction (about 80%, stoichiometrically), however, could be represented by a general equation of -d[Fe(III)]/dt = k[Fe(III)],(1. 811) where k is a rate constant and [Fe(III)] is the total ferric concentration. The rate constant decreased 1 order of magnitude as pH increased from 5 to 6. Aging of Fe(III) solution slows its reduction rate at pH 6 but not at pH 5.

Federal and state laws require that raw and cooked meats be accurately represented as to the species of meat they contain. A total of 806 raw and 96 cooked meat samples collected from Florida retail markets were examined for regulatory control of these products. An agar-gel immunodiffusion method was used for the identification of beef, pork and horse species in uncured raw meats. Enzyme-linked immunosorbent assays were used to identify poultry and sheep in raw meats and all species in cured raw meats and cooked meats. A positive violative sample was reported only if the target extraneous species present exceeded a 1% level. Results indicated that the overall rate of substituted species in both cooked and raw meat samples was 16.6%. Percentage of violation in cooked products was higher than that in raw meats (22.9% versus 15.9%). The undeclared species found in ground beef and veal products included sheep, pork and poultry, in descending order of frequency. The major substituting species found in ground pork, ground turkey and ground lamb, however, was beef. Horse meat was not detected in any sample tested. Intact pieces of raw meat tested were all correctly labeled. The source of substitution/contamination also was investigated and discussed. Current retail practices in meat markets show a significant problem with mixing of undeclared species in ground and comminuted meat products.