ABSTRACT
Fire is an essential Earth system process that alters ecosystem and atmospheric composition. Here we assessed long-term fire trends using multiple satellite data sets. We found that global burned area declined by 24.3 ± 8.8% over the past 18 years. The estimated decrease in burned area remained robust after adjusting for precipitation variability and was largest in savannas. Agricultural expansion and intensification were primary drivers of declining fire activity. Fewer and smaller fires reduced aerosol concentrations, modified vegetation structure, and increased the magnitude of the terrestrial carbon sink. Fire models were unable to reproduce the pattern and magnitude of observed declines, suggesting that they may overestimate fire emissions in future projections. Using economic and demographic variables, we developed a conceptual model for predicting fire in human-dominated landscapes.
Subject(s)
Climate , Ecosystem , Fires , Satellite Imagery , Agriculture , Carbon Sequestration , Conservation of Natural Resources , Human Activities , Models, TheoreticalABSTRACT
The official AOAC method for extracting penicillin from feeds allows some chlortetracycline to be co-extracted if the latter is also present in the sample. This can cause a high bias in results obtained by using the turbidimetric assay in which the test organism is sensitive to both antibiotics. In this report, we show that magnesium ions can be used to circumvent the interference of chlortetracycline in the turbidimetric assay for penicillin.
Subject(s)
Animal Feed/analysis , Chlortetracycline/analysis , Magnesium Sulfate , Penicillins/analysis , Drug Contamination , Nephelometry and TurbidimetryABSTRACT
Vitamin B12 was determined in dry feeds by atomic absorption spectrophotometry (AAS). Samples containing B12 were extracted with an assay solution, 5 g EDTA was added to the filtrate, the pH was adjusted to 7 with NH4OH, and 5 g charcoal was added. The charcoal was removed by filtering through ashless paper which was then placed in a beaker and ashed at 600 degrees C. After dissolving the cobalt oxide from the ash in 5N HNO3, cobalt content was determined by using AAS. To determine mg B12/lb feed, ppm cobalt in the feed is multiplied by 10.43. The sensitivity of the proposed procedure is 1 mg vitamin B12/lb. The procedure is rapid and precise, and results compare favorably with AOAC method 43.109.
