Lake characteristics influence recovery of microplankton in arctic LTER lake following experimental fertilization

Lakes N-1 and N-2 at the Arctic Long Term Ecological Research site at Toolik Lake, Alaska, U.S.A. were fertilized with nitrogen and phosphorus for 5 and 6 years, respectively. The response and recovery of the microplankton community (protozoans, rotifers and crustacean nauplii) differed in the two lakes. Microplankton biomass in Lake N-1 increased five-fold while that in Lake-N-2 only doubled, despite larger nutrient additions to N-2. Microplankton community structure in Lake N-1 shifted toward dominance by few taxa, while the community in Lake N-2 maintained diversity. Finally, the recovery of Lake N-1 to near prefertilization microplankton biomass levels was rapid, while Lake N-2 showed at least a 1-year lag in recovery. These differences appear to be related to differences in the structure of lake sediments

A critical evaluation of cathode materials for lithium-ion electric vehicle batteries

There has been an intensive research and development focus on lithium-ion batteries, which have revolutionized the electric vehicle market due to the batteries’ high energy and power density, longer lifespan, and increased safety than compa-rable rechargeable battery technologies. The performance of lithium-ion batteries is achieved by packaging design, electrolyte, and electrodes material’s selection. This study focuses on cathode materials as they currently need to overcome criti-cal challenges. In fact, cathode materials affect energy density, rate capability and working voltage that led to the cathode currently costing twice as much as the anode. For this reason, this study reviews cathode materials for electric vehicle lithium-ion batteries under economic and environmental perspectives to optimize the batteries’ structures and properties. Findings reveal that presently there is no commercially installed battery that can satisfy both, economic and environmental concerns while offering an overall excellent performance.Postprint (published version

Sources and transport of nitrogen in arid urban watersheds

Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3–) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3– (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3– during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover—retention basins, pipes, and grass cover—dictated the sourcing of NO3– in runoff. Urban watersheds were strong sinks or sources of N to stormwater depending on runoff, which in turn was inversely related to retention basin density and positively related to imperviousness and precipitation. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the time scale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms