Effects of shoreline sensitivity on oil spill trajectory modeling of the Lower Mississippi River

Background, aim, and scope  

The Lower Mississippi River is a major transportation route for commercial goods and petroleum products produced and refined locally. Oil spills caused by vessel accidents and equipment failure at refineries are a serious threat to the drinking water supply of Southern Louisiana, as well as to the many natural, economic, and social resources supported by the river. Providing accurate trajectory modeling to contingency planners is critical to protecting the local environment. The majority of trajectory model results, assuming a uniform shoreline, show 60–70% of spilled oil can be retained. This study examines the impact of detailed shoreline mapping that captures spatial and temporal changes in shoreline type on oil spill trajectory modeling.     

Heavy metal immobilization by chemical amendments in a polluted soil and influence on white lupin growth

The effects of chemical amendments (zeolite, compost and calcium hydroxide) on the solubility of Pb, Cd and Zn in a contaminated soil were determined. The polluted soil was from the Southwest Sardinia, Italy. It showed very high total concentrations of Pb (19663 mgkg(-1) d.m.), Cd (196 mgkg(-1) d.m.) and Zn (14667 mgkg(-1) d.m.). The growth and uptake of heavy metals by white lupin (Lupinus albus L., cv. Multitalia) in amended soils were also studied in a pot experiment under greenhouse conditions. Results showed that the amendments increased the residual fraction of heavy metals in the soils, and decreased the heavy metals uptake by white lupin compared with the unamended control. Among the three amendments, compost and Ca(OH)2 were the most efficient at reducing Pb and Zn uptake, while zeolite was the most efficient at reducing Cd uptake by the plants. White lupin growth was better in amended soils than in unamended control. The above ground biomass increased with a factor 1.8 (soil amended with zeolite), 3.6 (soil amended with compost) and 3.1 (soil amended with Ca(OH)2) with respect to unamended soil. The roots biomass increased with a factor 1.4 (soil amended with zeolite), 5.6 (soil amended with compost) and 4.8 (soil amended with Ca(OH)2). Results obtained suggest that the soil chemical treatment improved the performance of crops by reducing bioavailability of metals in the soils. However it would be therefore interesting to find a suitable mixture of these amendments to contemporarily immobilize the three main pollutants in the polluted soils.     

Floating aquatic macrophytes for the treatment of aquaculture effluents

Environmental Science and Pollution Research - Aquaculture is an activity with economic and social importance since it generates food, employment, and income. However, like other human activities,...     

Carbon substrate usage by zooplankton-associated bacteria,phytoplankton-associated bacteria,and free-living bacteria under aerobic and anaerobic conditions

Mesozooplankton provide oxic and anoxic microhabitats for associated bacteria, whose carbon substrate usage activities complement those of the ambient bacteria. The metabolic profiles of bacterial communities associated with the calanoid copepod Acartia tonsa under aerobic and anaerobic conditions were examined in comparison with phytoplankton-associated bacteria. Carbon substrate usage by phytoplankton-associated bacteria was significantly different than that of copepod-associated bacteria in both aerobic and anaerobic conditions. Substrate utilization by copepod-associated bacteria was more dependent upon oxygen condition than whether the bacteria were located on the copepod exoskeleton or within the gut. Results suggest that gut bacteria were responsible for a large portion of anaerobic substrate usage by copepod-associated bacteria. The metabolic profiles of bacteria associated with six common zooplankton groups and free-living bacteria collected in July 2012 from the York River estuary, Virginia, (37°14′50.36″N, 76°29′58.03W) were also compared, and there were significant differences in their substrate utilization patterns between aerobic and anaerobic incubations, and among the different zooplankton groups. Through trophic interactions, phytoplankton-associated or free-living bacteria may be introduced to the anoxic zooplankton gut and its associated bacterial community. Inclusion of these anaerobic microenvironments and their microbial inhabitants increased the total number of substrates used by 57 % over what was used by aerobic phytoplankton-associated bacteria alone, and by 50 % over what was used by aerobic free-living bacteria in the York River. Therefore, the presence of zooplankton-associated microhabitats and their bacteria expanded the functionality of aquatic microbial communities and led to a more comprehensive substrate usage.     

Effect of cell physicochemical characteristics and motility on bacterial transport in groundwater

The influence of physicochemical characteristics and motility on bacterial transport in groundwater were examined in flow-through columns. Four strains of bacteria isolated from a crystalline rock groundwater system were investigated, with carboxylate-modified and amidine-modified latex microspheres and bromide as reference tracers. The bacterial isolates included a gram-positive rod (ML1), a gram-negative motile rod (ML2), a nonmotile mutant of ML2 (ML2m), and a gram-positive coccoid (ML3). Experiments were repeated at two flow velocities, in a glass column packed with glass beads, and in another packed with iron-oxyhydroxide coated glass beads. Bacteria breakthrough curves were interpreted using a transport equation that incorporates a sorption model from microscopic observation of bacterial deposition in flow-cell experiments. The model predicts that bacterial desorption rate will decrease exponentially with the amount of time the cell is attached to the solid surface. Desorption kinetics appeared to influence transport at the lower flow rate, but were not discernable at the higher flow rate. Iron-oxyhydroxide coatings had a lower-than-expected effect on bacterial breakthrough and no effect on the microsphere recovery in the column experiments. Cell wall type and shape also had minor effects on breakthrough. Motility tended to increase the adsorption rate, and decrease the desorption rate. The transport model predicts that at field scale, desorption rate kinetics may be important to the prediction of bacteria transport rates.