Contamination of aquatic habitats with pharmaceuticals is a major environmental concern. Recent studies have detected pharmaceutical pollutants in a wide array of ecosystems and organisms, with many of these contaminants being highly resistant to biodegradation and capable of eliciting sub-lethal effects in non-target species. One such pollutant is fluoxetine, a widely prescribed antidepressant, which is frequently detected in surface waters globally and can alter physiology and behaviour in aquatic organisms. Despite this, relatively little is known about the potential for fluoxetine to disrupt mechanisms of sexual selection. Here, we investigate the impacts of 30-day exposure to two environmentally realistic levels of fluoxetine (low and high) on mechanisms of pre- and post-copulatory sexual selection in the eastern mosquitofish (Gambusia holbrooki). We tested 1) male mating behaviour in the absence or presence of a competitor male, and 2) sperm quality and quantity. We found that high-fluoxetine exposure increased male copulatory behaviour in the absence of a competitor, while no effect was detected under male-male competition. Further, fluoxetine exposure at both concentrations increased total sperm count relative to males from the control group, while no significant change in sperm quality was observed. Lastly, low-fluoxetine males showed a significant reduction in condition index (mass relative to length). Our study is the first to show altered mechanisms of both pre- and post-copulatory sexual selection in an aquatic species resulting from environmentally realistic fluoxetine exposure, highlighting the capacity of pharmaceutical pollution to interfere with sensitive reproductive processes in wildlife.

Crumpled graphene oxide nanosheets have drawn large attentions due to its compressibility and self-avoiding stacking as flat graphene sheets trend to aggregate and restack. Up to now, most of the synthesis approaches were relied on external substrates, such as elastic substrates or ultrasonic atomizer, and the crumpled structures were obtained in a solid state directly. Here we report a facile method to produce crumpled dispersive nanosheets in solution through general base-washing treatment by taking advantage of the amphipathy of GO nanosheets. With the dissociation of oxygen-functional groups on nanosheets in alkaline environment, highly water-soluble oxidative debris (OD) would fall off from the nanosheets due to the increase of electrostatic repulsions, and resulted in the crumple of the flat sheets, while the covalent oxygen-functional groups on the nanosheets were reserved. As a result, the nanosheets remained dispersible in solution, and could be used directly for surface modifications. Pt nanoparticles could be directly deposited onto both sides of the sheets through common nucleation and growth from precursor ions process. Compared with flat graphene-based hybrid, the catalytic performance of crumpled-graphene-Pt (CG-Pt) is more excellent and attractive, and corresponding apparent kinetic rate constant (kₐₚₚ) of CG-Pt toward 4-nitrophenol reduction is enhanced by 2.7–4.6-fold. This study provides a new and facile way to fabricate crumpled nanosheets and demonstrates to be easy modified for various purpose.

Ionizing γ-irradiation and solvent-assisted spiking are frequently applied to eliminate microbial activity and to induce hydrophobic organic compounds (HOCs) into soil, respectively, when studying the accumulation of chemicals in terrestrial organisms. However, the side-effects that may arise from these treatments on soil-HOC interaction and, subsequently, the kinetics and extents of bioaccumulation are not thoroughly understood. To this end, the accumulation of 1,1-dichloro-2,2-bis(p-chlorophenyl)etylene (p,p’-DDE) by Eisenia andrei was studied in sterilized or unsterilized and freshly spiked (FS) or historically contaminated (HC) soils in parallel with an analysis of aliphatic and hydrophilic soil organic matter (SOM) moieties using mid-infrared diffuse reflectance spectroscopy (DRIFT-S). Irradiation did not impart significant changes on spectral SOM descriptors. In contrast, earthworm inhabitation increased the relative presence of aliphatic moieties to a greater extent than hydrophilic ones, reaching or exceeding pre-treatment levels. Overall, effects on SOM chemistry can be ranked as earthworms > spiking > irradiation. Corresponding changes at the bioaccumulation level were observed for the FS soil (i.e., a 27% reduction in bioaccumulation upon sterilization) but not for the HC soil. This implies that in contrast to the interactions between aged p,p’-DDE and sterilized HC soil, the interactions established between freshly added p,p’-DDE and sterilized FS soil were altered by γ-irradiation-induced secondary effects alone or in combination with earthworm inhabitation. Thus, although the soil treatment processes studied here should not drastically impact compound bioaccumulation, they should be considered in mechanistic studies where the qualitative and quantitative aspects of compound-soil (organic matter)-earthworm interactions are at the centre of attention.

To investigate the chronic toxicity of graphene oxide (GO) and its functionalized products (GO-carboxyl, GO-imidazole and GO-polyethylene glycol), a two-generation study was conducted using the aquatic model species Daphnia magna. Each generation of daphnids were exposed for 21 days to 1.0 mg L−1 graphene material, with body length, neonate number, time of first brood and the intrinsic rate of natural increase (r) assessed as endpoints. Chronic exposure to GO, GO-carboxyl, and GO-imidazole had no adverse effect on body length or offspring number in the daphnid F0 generation, however, this exposure paradigm led to significant growth or reproduction inhibition in the following generation. Meanwhile, GO was found to show the strongest inhibitory effect, sequentially followed by GO-carboxyl and GO-imidazole. With exposure to GO-polyethylene glycol, no significant effects on growth or reproduction were observed for both F0 and F1 generation daphnids. These results reveal that carboxyl, imidazole and polyethylene glycol functional attachments alleviate the bio-toxicity of GO, especially polyethylene glycol. The increased C/O atomic ratio present in GO-carboxyl, GO-imidazole and GO-polyethylene glycol due to functionalization may mainly explain the reduced toxicity.

Microplastics are an emerging contaminants of concern in aquatic environments. The aggregation behaviors of microplastics governing their fate and ecological risks in aquatic environments is in need of evaluation. In this study, the aggregation behavior of polystyrene microspheres (micro-PS) in aquatic environments was systematically investigated over a range of monovalent and divalent electrolytes with and without natural organic matter (i.e., Suwannee River humic acid (HA)), at pH 6.0, respectively. The zeta potentials and hydrodynamic diameters of micro-PS were measured and the subsequent aggregation kinetics and attachment efficiencies (α) were calculated. The aggregation kinetics of micro-PS exhibited reaction- and diffusion-limited regimes in the presence of monovalent or divalent electrolytes with distinct critical coagulation concentration (CCC) values, followed the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The CCC values of micro-PS were14.9, 13.7, 14.8, 2.95 and 3.20 mM for NaCl, NaNO3, KNO3, CaCl2 and BaCl2, respectively. As expected, divalent electrolytes (i.e., CaCl2 and BaCl2) had stronger influence on the aggregation behaviors of micro-PS as compared to monovalent electrolytes (i.e., NaCl, NaNO3 and KNO3). HA enhanced micro-PS stability and shifted the CCC values to higher electrolyte concentrations for all types of electrolytes. The CCC values of micro-PS were lower than reported carbonaceous nanoparticles CCC values. The CCC[Ca2+]/CCC [Na+] ratios in the absence and presence of HA at pH 6.0 were proportional to Z−2.34 and Z−2.30, respectively. These ratios were in accordance with the theoretical Schulze–Hardy rule, which considers that the CCC is proportional to z−6–z−2. These results indicate that the stability of micro-PS in the natural aquatic environment and the possibility of significant aqueous transport of micro-PS.

This study tested the hypothesis that different diets could modulate mercury (Hg) trophic transfer by concurrently altering the transfer of energy (in terms of growth) and transfer of Hg (in terms of biodynamic process). Firstly, we conducted a 40-d laboratory bioaccumulation experiment, in which tilapia (Oreochromis niloticus) was exposed to inorganic mercury (Hg[II]) and methylmercury (MeHg) via feeding on three distinct diets (macrophyte, freshwater shrimp, and commercial pellets) at a fixed ingestion rate of 0.065 g g⁻¹ d⁻¹. During the dietary exposure period, tilapia exhibited Hg species- and diet-dependent Hg trophic transfer patterns and diet-specific growth rates. We then employed a biokinetic model to assess how diet-specific biodynamics and/or diet-specific growth rates modulated the overall Hg bioaccumulation and trophic transfer. The diet-specific assimilation efficiencies (AEs) were monitored using radioisotope technique, and the determined AEs of Hg(II) (8.6%–29.7%) varied by 3.5 times among diets whereas the MeHg AEs (94.4%–97.1%) were not affected. The biokinetic modeling further revealed that Hg(II) trophic transfer in tilapia was controlled by the diet-specific AEs, while MeHg trophic transfer was governed by the diet-specific growth rates. Specifically, a diet-derived high growth rate reduced the MeHg trophic transfer in pellets-fed tilapia, and the overall accumulated MeHg level in fish was under the control of both somatic growth dilution and dietary MeHg influx. Moreover, we observed that the Hg levels (mainly as MeHg) in fast-growing farmed tilapia were significantly lower than wild-living tilapia after 100 d exposure in the field, attributed to somatic growth dilution (SGD). Both the laboratory and field study therefore demonstrated the importance of diet-derived SGD in modulating mercury trophic transfer in aquatic food webs.

The linkage between ambient air pollution exposure and occurrence of diabetes mellitus is not well defined. This study examined the association between exposure to fine particles (PM₂.₅) and the prevalence of diabetes among Chinese elderly people. We surveyed 11,504 adults aged ≥50 years in China, estimated the annual concentrations of ambient PM₂.₅ using a satellite-based model of aerosol optical depth information. We employed a generalized mixed effects model to examine the association between PM₂.₅ and the prevalence of diabetes and explored potential effect modifiers. We estimated diabetes burden attributable to ambient PM₂.₅ if the observed association is indeed causal. The diabetes prevalence among the participants was 6.5% (n = 745). Our analysis found a statistically significant association between PM₂.₅ and diabetes. The adjusted odds ratio was 1.27 (95% confidence interval (CI), 1.12, 1.43) for each 10 μg/m³ increment in ambient PM₂.₅. Stratified analyses found a lower association among the participants with higher consumption of fruit. We estimated that 22.02% (95% CI: 8.59%, 43.29%) of the diabetes cases could be ascribable to ambient PM₂.₅. Our finding suggests that PM₂.₅ exposures could increase the risk of diabetes, and if causal, could be responsible for substantial burden of diabetes among the Chinese elderly; and higher intakes of fruit might reduce the harmful effects of PM₂.₅, however, due to the limitation of the cross-sectional study design, more studies are warranted to confirm this observation.

Climate change and human activities induce an increased frequency and intensity of cyanobacterial blooms which could release toxins to aquatic ecosystems. Zooplankton communities belong to the first affected organisms, but in tropical freshwater ecosystems, this issue has yet been poorly investigated. We tested two questions (i) if the tropical Daphnia lumholtzi is capable to develop tolerance to an ecologically relevant concentration of purified microcystin-LR and microcystins from cyanobacterial extract transferable to F1 and F2 generations? And (ii) would F1 and F2 generations recover if reared in toxin-free medium? To answer these questions, we conducted two full factorial mutigenerational experiments, in which D. lumholtzi was exposed to MC-LR and cyanobacterial extract at the concentration of 1 μg L⁻¹ microcystin continuously for three generations. After each generation, each treatment was spit into two: one reared in the control (toxin free) while the other continued in the respective exposure. Fitness-related traits including survival, maturity age, body length, and fecundity of each D. lumholtzi generation were quantified. Though there were only some weak negative effects of the toxins on the first generation (F0), we found strong direct, accumulated and carried-over impacts of the toxins on life history traits of D. lumholtzi on the F1 and F2, including reductions of survival, and reproduction. The maturity age and body length showed some inconsistent patterns between generations and need further investigations. The survival, maturity age (for extract), and body length (for MC-LR) were only recovered when offspring from toxin exposed mothers were raised in clean medium for two generations. Chronic exposure to long lasting blooms, even at low density, evidently reduces survival of D. lumholtzi in tropical lakes and reservoirs with ecological consequences.

Marine organisms are naturally exposed to different environmental pollutants including organic pollutants and nanoparticles. The interactive effects between nanoparticles and other chemicals on aquatic organisms have raised concerns regarding the potential of nanomaterials as the vector for other chemicals. In the present study, the effect of nano zinc oxide (nZnO) on the bioavailability of triphenyltin chloride (TPTCl) was studied, and their combined acute and reproductive toxicity to the marine copepod Tigriopus japonicus were evaluated. At experimental concentration ranges of nZnO in this study, the percentage of dissolution of Zn²⁺ was relative stable (from 62% to 66%), and nZnO did not affect the bioavailability of TPTCl to the copepods. The acute toxicity of binary mixtures of nZnO/TPT was equivalent to that of the mixture of Zn²⁺/TPT. In agreement with the decrease in TPTCl's LC₅₀ values at the presence of nZnO, their interacting effect was synergistic based on response addition response surface model, and the interacting parameter was modelled to be −1.43. In addition to acute toxicity test, reproductive toxicity tests revealed that exposure to nZnO and TPTCl didn't affect the successful mating rate and the number of nauplii in the 1st brood, but they extended the time for the eggs to hatch from 2.53 days to 3.94 and 3.64 days, respectively. The exposure to nZnO/TPTCl mixture delayed the time to hatch to 5.78 days.

This study presents the results of field experiments that were designed to investigate the photophysiological characteristics of microphytobenthos (MPB) and to estimate primary production (PP) in Daebu mudflat, which is located at the west coast of Korea. A typical seasonal (or monthly) fluctuation of intertidal MPB PP was found in association with biotic (benthic Chl-a) and/or abiotic parameters (irradiance and temperature) over a period of three years. From a series of field-laboratory experiments using the oxygen micro-profiling method (totaling 28 surveys), three consistent phenomena were observed: 1) winter to early spring algal blooms, 2) seasonal changes in Q10, and 3) temperature dependent MPB photosynthesis-irradiance (P-I). In particular, both the chlorophyll-specific maximum photosynthetic capacity (Pbmax) and the saturated light intensity (Ik), derived from 126 P-I curves (1870 data sets of oxygen micro-profiling in the sediment), were significantly correlated with sediment temperature (p < 0.01). To develop an empirical MPB PP model, the relationships between P-I parameters and environmental variables were parameterized following established exponential forms (e.g., Q10). It was possible to estimate the MPB PP in Daebu mudflat area by using easily accessible explanatory factor, suitable to be used for future explorations of parameters such as sediment temperature, irradiance, chlorophyll concentration, and tidal height. The estimated annual MPB PP based on the empirical PP model were found to be greater than that in the Wadden Sea and average annual PP in the temperate zones of the world. Authors believe that the present approach of the MPB PP estimation could be combined with remote-sensing techniques (e.g., satellites) to support coastal ecosystem management.