Differential Reactivity of Copper- and Gold-Based Nanomaterials Controls Their Seasonal Biogeochemical Cycling and Fate in a Freshwater Wetland Mesocosm.

Reliable predictions of the environmental fate and risk of engineered nanomaterials (ENMs) require a better understanding of ENM reactivity in complex, biologically active systems for chronic low-concentration exposure scenarios. Here, simulated freshwater wetland mesocosms were dosed with ENMs to assess how their reactivity and seasonal changes in environmental parameters influence ENM fate in aquatic systems. Copper-based ENMs (Kocide), known to dissolve in water, and gold nanoparticles (AuNPs), stable against dissolution in the absence of specific ligands, were added weekly to mesocosm waters for 9 months. Metal accumulation and speciation changes in the different environmental compartments were assessed over time. Copper from Kocide rapidly dissolved likely associating with organic matter in the water column, transported to terrestrial soils and deeper sediment where it became associated with organic or sulfide phases. In contrast, Au accumulated on/in the macrophytes where it oxidized and transferred over time to surficial sediment. A dynamic seasonal accumulation and metal redox cycling were found between the macrophyte and the surficial sediment for AuNPs. These results demonstrate the need for experimental quantification of how the biological and chemical complexity of the environment, combined with their seasonal variations, drive the fate of metastable ENMs.

Size-Based Differential Transport, Uptake, and Mass Distribution of Ceria (CeO2) Nanoparticles in Wetland Mesocosms.

Trace metals associated with nanoparticles are known to possess reactivities that are different from their larger-size counterparts. However, the relative importance of small relative to large particles for the overall distribution and biouptake of these metals is not as well studied in complex environmental systems. Here, we have examined differences in the long term fate and transport of ceria (CeO2) nanoparticles of two different sizes (3.8 vs 185 nm), dosed weekly to freshwater wetland mesocosms over 9 months. While the majority of CeO2 particles were detected in soils and sediments at the end of nine months, there were significant differences observed in fate, distribution, and transport mechanisms between the two materials. Small nanoparticles were removed from the water column primarily through heteroaggregation with suspended solids and plants, while large nanoparticles were removed primarily by sedimentation. A greater fraction of small particles remained in the upper floc layers of sediment relative to the large particles (31% vs 7%). Cerium from the small particles were also significantly more bioavailable to aquatic plants (2% vs 0.5%), snails (44 vs 2.6 ng), and insects (8 vs 0.07 µg). Small CeO2 particles were also significantly reduced from Ce(IV) to Ce(III), while aquatic sediments were a sink for untransformed large nanoparticles. These results demonstrate that trace metals originating from nanoscale materials have much greater potential than their larger counterparts to distribute throughout multiple compartments of a complex aquatic ecosystem and contribute to the overall bioavailable pool of the metal for biouptake and trophic transfer.

Examination of the difficulties in emotion regulation scale and its relation to disordered eating in a young female sample.

OBJECTIVE: Difficulties with emotion regulation is considered an important maintaining factor of disordered eating. One of the most commonly used measures of this construct is the Difficulties in Emotion Regulation Scale (DERS). The aim of this study was to explore the factor structure of this measure in young females and to examine its reliability and validity with respect to disordered eating. METHOD: Females aged 17-25 years (M age = 19.6 years, N = 486) were examined in the analyses. Confirmatory factor analyses were conducted followed by regression analyses examining the DERS subscales as predictors of eating disorder severity and disordered eating behaviors. RESULTS: The original 6-factor 36-item model did not fit well and analyses indicated a 6-factor 30-item solution was a more suitable fit for our population. Validity and reliability of the 30-item solution were found to be acceptable. Regression analyses also indicated the 36- and 30-item models were able to adequately predict eating disorder severity and disordered eating behaviors with the "Awareness" and "Goals" subscales being predictors of the former, and the "Impulsivity" subscale being a significant predictor of the latter. DISCUSSION: The overall findings suggest that an abbreviated version of the DERS might be more appropriate than the original version with young females and that this measure exhibits stronger relationships with eating disorder severity and disordered eating behaviors than the longer version. Further examinations of the psychometric properties of the DERS with clinical populations are indicated.