Estimating Nitrogen Load Resulting from Biofuel Mandates.

The Energy Policy Act of 2005 and the Energy Independence and Security Act (EISA) of 2007 were enacted to reduce the U.S. dependency on foreign oil by increasing the use of biofuels. The increased demand for biofuels from corn and soybeans could result in an increase of nitrogen flux if not managed properly. The objectives of this study are to estimate nitrogen flux from energy crop production and to identify the catchment areas with high nitrogen flux. The results show that biofuel production can result in an increase of nitrogen flux to the northern Gulf of Mexico from 270 to 1742 thousand metric tons. Using all cellulosic (hay) ethanol or biodiesel to meet the 2022 mandate is expected to reduce nitrogen flux; however, it requires approximately 25% more land when compared to other scenarios. Producing ethanol from switchgrass rather than hay results in three-times more nitrogen flux, but requires 43% less land. Using corn ethanol for 2022 mandates is expected to have double the nitrogen flux when compared to the EISA-specified 2022 scenario; however, it will require less land area. Shifting the U.S. energy supply from foreign oil to the Midwest cannot occur without economic and environmental impacts, which could potentially lead to more eutrophication and hypoxia.

Bioconcentration and depuration of (14)C-labeled 17α-ethinyl estradiol and 4-nonylphenol in individual organs of the marine bivalve Mytilus edulis L. .

Endocrine-disrupting compounds (EDCs), including 17α-ethinyl estradiol (EE2) and 4-nonylphenol (4-NP), enter coastal environments primarily in effluents of wastewater treatment facilities and have become ubiquitous in marine surface waters, sediments, and biota. Although EE2 and 4-NP have been detected in marine shellfish, the kinetics of bioconcentration and their tissue distribution have not been thoroughly investigated. The authors performed bioconcentration and depuration experiments in the blue mussel, Mytilus edulis, with 3.37 nM EE2 (0.999 µg/L) and 454 nM 4-NP (100.138 µg/L). Mussels and seawater were sampled throughout a 38-d exposure and a 35-d depuration period, and 6 tissues were individually assayed. Uptake of EE2 and 4-NP was curvilinear throughout exposure and followed a similar uptake pattern: digestive gland > gill ≥ remaining viscera > gonad > adductor > plasma. Depuration varied, however, with half-lives ranging from 2.7 d (plasma) to 92 d (gill) for EE2 and 15 d (plasma) to 57 d (gill) for 4-NP. An innovative modeling approach, with 3 coupled mathematical models, was developed to differentiate the unique roles of the gill and plasma in distributing the EDCs to internal tissues. Plasma appears pivotal in regulating EDC uptake and depuration within the whole mussel.