RESUMEN
Complex metal oxide nanomaterials, like lithiated cobalt oxide (LCO) nanosheets, are among the most widespread classes of nanomaterials on the market. Their ubiquitous application in battery storage technology drives their production to rates of environmental significance without sufficient infrastructure for proper disposal/recycling, thus posing a risk to ecosystem health and sustainability. The present study assesses the general toxicological impacts of LCO when exposed to Raphidocelis subcapitata; physiological endpoints relating to growth and energy production are considered. Algal growth inhibition was significantly increased at concentrations as low as 0.1 µg ml-1 , while exhibiting a median effect concentration of 0.057 µg ml-1 . The average biovolume of cells was significantly enlarged at 0.01 µg ml-1 , thus indicating increased instances of cell cycle arrest in LCO-treated cells. In addition, LCO-treated cells produced significantly less carbon biomass while significantly overproducing neutral lipid content starting at 0.1 µg ml-1 , thus indicating interference with CO2 assimilation chemistry and/or carbon partitioning. However, the relative abundance of chlorophyll was significantly increased, likely to maximize light harvesting and compensate for photosynthetic interference. Cells that were treated with dissolved Li+ /Co2+ ions did not significantly impact any of the endpoints tested, suggesting that LCO phytotoxicity is mainly induced through nano-specific mechanisms rather than ion-specific ones. These results indicate that this type of nanomaterial can significantly impact the way this alga proliferates, as well as the way it produces and stores its energy, even at lower, sublethal, concentrations. Furthermore, impairments to crucial cellular pathways, like carbon assimilation, could potentially cause implications at the ecosystem level. Thus, in future work, it will be important to characterize the molecular mechanisms of LCO at the nano-bio interface. Environ Toxicol Chem 2023;42:1451-1462. © 2023 SETAC.
Asunto(s)
Nanoestructuras , Contaminantes Químicos del Agua , Ecosistema , Cobalto/toxicidad , Óxidos/toxicidad , Nanoestructuras/toxicidad , Contaminantes Químicos del Agua/toxicidadRESUMEN
A simple algebraic equation is presented here to estimate the magnitude of groundwater velocity based on data from a single-well injection-drift test thereby eliminating the time-consuming and costly extraction phase. A volume of tracer-amended water was injected by forced-gradient into a single well followed by monitoring of the conservative solute tracers under natural-gradient conditions as their upgradient portions drifted back through the well. The breakthrough curve data from the single well during the drift phase was analyzed to determine the mean travel times of the tracers. The estimated mean upgradient travel distance back through the single well and the mean travel times of the tracers were used in a simple algebraic equation to estimate groundwater velocity. The groundwater velocity based on the single-well injection-drift test was estimated to be approximately 0.64 ft per day. Two transects of observation wells were used to monitor the natural-gradient tracer transport downgradient of the injection well. The one-dimensional, or dual-well, transport of the tracer from the injection well to the nearest downgradient observation well indicated that the groundwater velocity was 0.55 ft per day. The two-dimensional, or multi-well, transport of the center of mass of the tracers indicated that the groundwater velocity was 0.60 ft per day; the dual- and multi-well results were in excellent agreement with those from the single-well and validated the simple algebraic equation. The new single-well method presented here is relatively simple, rapid, and does not require an extraction phase.