Release of antibiotics into the environment, which often occurs downstream of wastewater treatment plants, poses a human health threat due to the potential development of bacterial antibiotic resistance. In this study, laboratory experiments were conducted to evaluate the performance of ball milled biochar on the removal of two sulfonamide antibiotics, sulfamethoxazole (SMX) and sulfapyridine (SPY) from water and wastewater. Aqueous batch sorption experiment using both pristine and ball milled biochar derived from bagasse (BG), bamboo (BB) and hickory chips (HC), made at three pyrolysis temperatures (300, 450, 600 °C), showed that ball milling greatly enhanced the SMX and SPY adsorption. The 450 °C ball milled HC biochar and BB biochar exhibited the best removal efficiency for SMX (83.3%) and SPY (89.6%), respectively. A range of functional groups were produced by ball milling, leading to the conclusion that the adsorption of sulfonamides on the biochars was controlled by multiple mechanisms including hydrophobic interaction, π–π interaction, hydrogen bonding, and electrostatic interaction. Due to the importance of electrostatic interaction, SMX and SPY adsorption was pH dependent. In laboratory water solutions, the Langmuir maximum adsorption capacities of SMX and SPY reached 100.3 mg/g and 57.9 mg/g, respectively. When tested in real wastewater solution, the 450 °C ball milled biochar still performed well, especially in the removal of SPY. The maximum adsorption capacities of SMX and SPY in wastewater were 25.7 mg/g and 58.6 mg/g, respectively. Thus, ball milled biochar has great potential for SMX and SPY removal from aqueous solutions including wastewater.

Although nanoscale surface roughness has been theoretically demonstrated to be a crucial factor in the interaction of colloids and surfaces, little experimental research has investigated the influence of roughness on colloid or silver nanoparticle (AgNP) retention and release in porous media. This study experimentally examined AgNP retention and release using two sands with very different surface roughness properties over a range of solution pH and/or ionic strength (IS). AgNP transport was greatly enhanced on the relatively smooth sand in comparison to the rougher sand, at higher pH, and lower IS and fitted model parameters showed systematic changes with these physicochemical factors. Complete release of the retained AgNPs was observed from the relatively smooth sand when the solution IS was decreased from 40 mM NaCl to deionized (DI) water and then the solution pH was increased from 6.5 to 10. Conversely, less than 40% of the retained AgNPs was released in similar processes from the rougher sand. These observations were explained by differences in the surface roughness of the two sands which altered the energy barrier height and the depth of the primary minimum with solution chemistry. Limited numbers of AgNPs apparently interacted in reversible, shallow primary minima on the smoother sand, which is consistent with the predicted influence of a small roughness fraction (e.g., pillar) on interaction energies. Conversely, larger numbers of AgNPs interacted in deeper primary minima on the rougher sand, which is consistent with the predicted influence at concave locations. These findings highlight the importance of surface roughness and indicate that variations in sand surface roughness can greatly change the sensitivity of nanoparticle transport to physicochemical factors such as IS and pH due to the alteration of interaction energy and thus can strongly influence nanoparticle mobility in the environment.

Developmental exposures to estrogenic chemicals possibly cause structural and functional abnormalities of reproductive organs in vertebrates. Bisphenol AF (BPAF), a bisphenol A (BPA) analogue, has been shown to have higher estrogenic activity than BPA, but little is known about the effects of BPAF on gonadal development, particularly gonadal differentiation. We aimed to determine whether low concentrations of BPAF could disrupt gonadal differentiation and subsequent development using Xenopus laevis, a model species for studying feminizing effects of estrogenic chemicals. X. laevis tadpoles were exposed to BPAF (1, 10, 100 nM) or 17β-estradiol (E2, positive control) from stages 45/46 to 53 and 66 in a semi-static exposure system, with a prolonged treatment with the highest concentration to the eighth week post-metamorphosis (WPM8). Gonadal morphology and histology as well as sexually dimorphic gene expression were examined to evaluate the effects of BPAF. All concentrations of BPAF caused changes in testicular morphology at different developmental stages compared with controls. Specifically, at stage 53, BPAF like E2 resulted in decreases in both the size and the number of gonadal metameres (gonomeres) in testes, looking like ovaries. Some of BPAF-treated testes remained segmented and even became discontinuous and fragmented at subsequent stages. Histological abnormalities were also observed in BPAF-treated testes, such as ovarian cavity at stages 53 and 66 and poorly developed seminiferous tubules on WPM8. At the molecular level, BPAF inhibited expression of male highly expressed genes in testes at stage 53. Correspondingly, BPAF, like E2, inhibited cell proliferation in testes at stage 50. All results show that low concentrations of BPAF inhibited testicular differentiation and subsequent development in X. laevis, along with feminizing effects to some degree. Our finding implies a risk of BPAF to the male reproductive system of vertebrates including humans.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are cancerogenic organic pollutants that priority controlled by Stockholm Convention with globally 183 signatories now. Secondary nonferrous smelting plants are confirmed to be important sources in China due to its large industrial activities and high emissions of PCDD/Fs. It is important to prioritize source to achieve source emission reduction by conducting field monitoring on typical case plants. Here, the emission profiles and levels of PCDD/Fs were investigated in 25 stack gas samples collected from three secondary copper production (SeCu), two secondary zinc production (SeZn) and two secondary lead production (SePb). Both average mass concentration and toxic equivalency quantity (TEQ) concentrations of PCDD/Fs all generally decreased in the order: SeCu > SeZn > SePb. It is noteworthy that the mean TEQ concentration in stack gas from SeCu with oxygen-enrich melting furnace technology, at 2.7 ng I-TEQ/Nm³, was much higher than the concentrations of other smelting processes. The average emission factors and annual release amounts of PCDD/Fs from SeCu, SePb and SeZn investigated were 28.4, 1.5, 10.4 μg I-TEQ/t and 1.03, 0.023, 0.17 g I-TEQ/year, respectively. The ratios of 2,3,7,8-TCDF to 1,2,3,7,8-PeCDF and OCDD to 1,2,3,7,8,9-HxCDD varied to large extent for three metal smelting, which could be used as diagnostic ratios of tracing specific PCDD/Fs sources. Addition of copper-containing sludge into the raw materials might lead to higher PCDD/Fs emissions. It is important to emphasize and reduce the PCDD/Fs emissions from oxygen-enrich melting furnace from secondary copper productions.

Microplastics are ubiquitous in marine environments. Sediments and marine organisms are recognized as the carriers and final destinations of microplastics. However, research on the concentration and abundance of microplastics in deep-sea sediments and organisms is limited. In this study, samples of sediments and organisms were collected from deep-sea locations of the western Pacific Ocean, with the depth ranging from 4601 m to 5732 m. Microplastics were extracted from the samples and analyzed by micro-Fourier-transform infrared spectroscopy. The average abundance of microplastics in the sediments was 240 items per kg dry weight of sediment. The microplastics were predominantly fibrous in shape (52.5%), blue in color (45.0%), and less than 1 mm in size (90.0%). The most commonly detected polymers were poly(propylene-ethylene) copolymer (40.0%) and polyethylene terephthalate (27.5%). The concentrations of polychlorinated biphenyls (PCBs), which are representatives of persistent organic pollutants, in the pore water of sediment samples were also investigated. A significant correlation between the distribution of microplastics and the PCB concentrations in sediments was found (P = 0.016). Microplastics were also detected in deep-sea organisms (i.e., Crinoidea, Pheronematidae, Ophiuroidea, and Gammaridea) in the sampling region, with an abundance of 0–3 items per individual biological sample. This assessment of microplastics in deep-sea sediments and benthic organisms of the western Pacific Ocean confirms that microplastic pollution exists in the deep-sea ecosystems of this region.

Propylparaben is widely used as a preservative in pharmaceuticals and personal care products and is ultimately excreted by the human body. Thus, propylparaben reaches sewage and enters the soil environment by sludge fertilization and wastewater irrigation. However, there are few existing studies on the toxicity and risks of such chemicals in terrestrial environments. In this study, a multispecies bioassay for propylparaben was performed and protective concentrations (PCs) were derived based on toxicity values by probabilistic ecological risk assessment. Acute and chronic bioassays were conducted on 11 species in eight taxonomic groups (Magnoliopsida, Liliopsida, Clitellata, Entognatha, Entomobryomorpha, Chromadorea, Chlorophyceae, Trebouxiophyceae). Based on the toxicity values calculated, the PC₉₅ values for acute and chronic SSDs were 13 and 6 mg/kg dry soil, respectively. Toxicity varied among taxa, with soil algae emerging as the most sensitive to propylparaben. This may be attributable to differences in exposure pathways among species. The exposure pathway of propylparaben can be altered by adsorption to soil particles. As parabens are presently under-regulated globally in terms of their environmental effects, our findings can serve as the basis to propose standard values for environmental protection.

Polycyclic aromatic hydrocarbons (PAHs) are hazardous organic compounds with mutagenic, genotoxic and carcinogenic properties. Although PAHs in soil can cause toxicity to microorganisms, the microbial community is able to degrade these compounds. For this reason, it is important to study acute and short-term effects of PAH contamination on soil microbial community, also to shed light on its possible exploitation in soil restoration.The effects of acute PAH contamination on the structure and metabolic activity of microbial communities in three forest (beech, holm oak, black pine) soils were studied. The soils were spiked with phenanthrene, pyrene or benzo[a]pyrene and incubated in experimental mesocosms, under controlled conditions. Enzymatic activities (laccase, total peroxidase and hydrolase), as well as microbial biomass and community structure (through phospholipid fatty acid and ergosterol analyses), were evaluated in the three soil systems 4 days after contamination and compared to no-spiked soils. In soil under holm oak, there was a stimulation of Gram+ bacteria after contamination with all the 3 PAHs, whereas in soil under pine, pyrene and phenanthrene additions mainly stimulated fungi and actinomycetes.

The co-precipitation method was used to synthesize nano-magnetic adsorbent MnFe₂O₄ (nMFO), characterized through XRD, SEM, EDS, and BET techniques. The synthesized nMFO was used for hexavalent and trivalent chromium ions elimination from the aqueous phase. The optimum pH for the adsorption of Cr (VI) and Cr (III) was determined as 2 and 5, respectively. The chromium ions adsorption behavior was well interpreted through the pseudo-second order kinetics model. Furthermore, isotherm studies were conducted, and the obtained results indicated that Langmuir isotherm model could well justify the chromium ions adsorption process. Quick removal (less than 10 min) of both chromium ions and high removal efficiency were occurred using nMFO. The utmost adsorption capacity of trivalent and hexavalent chromium ions were determined as 39.6 and 34.84 mg g⁻¹, respectively. Thermodynamic studies on chromium adsorption revealed positive value for ΔH and negative value for ΔG, representing that chromium ions adsorption was an endothermic and spontaneous process. The multilinearity in the graphs of chromium ions adsorption was observed using intra-particle diffusion model. In this regard, the external mass transfer of chromium ions on synthesized nanoparticles was the important and controlling step in the adsorption process.

Whether toxicity of silver nanoparticles (AgNPs) to organisms originates from the nanoparticles themselves or from the dissolved Ag-ions is still debated, with the majority of studies claiming that extracellular release of Ag-ions is the main cause of toxicity. The objective of this study was to determine the contributions of both particles and dissolved ions to toxic responses, and to better understand the underlying mechanisms of toxicity. In addition, the pathways of AgNPs exposure to plants might play an important role and therefore are explicitly studied as well. We systematically assessed the phytotoxicity, internalization, biodistribution, and antioxidant responses in lettuce (Lactuca sativa) following root or foliar exposure to AgNPs and ionic Ag at various concentrations. For each endpoint the relative contribution of the particle-specific versus the ionic form was quantified. The results reveal particle-specific toxicity and uptake of AgNPs in lettuce as the relative contribution of particulate Ag accounted for more than 65% to the overall toxicity and the Ag accumulation in whole plant tissues. In addition, particle toxicity is shown to originate from the accumulation of Ag in plants by blocking nutrient transport, while ion toxicity is likely due to the induction of excess ROS production. Root exposure induced higher toxicity than foliar exposure at comparable exposure levels. Ag was found to be taken up and subsequently translocated from the exposed parts of plants to other portions regardless of the exposure pathway. These findings suggest particle related toxicity, and demonstrate that the accumulation and translocation of silver nanoparticles need to be considered in assessment of environmental risks and of food safety following consumption of plants exposed to AgNPs by humans.

This study presents the results of an integrated model developed to evaluate the environmental and health impacts of Electric Vehicle (EV) deployment in a large metropolitan area. The model combines a high-resolution chemical transport model with an emission inventory established with detailed transportation and power plant information, as well as a framework to characterize and monetize the health impacts. Our study is set in the Greater Toronto and Hamilton Area (GTHA) in Canada with bounding scenarios for 25% and 100% EV penetration rates. Our results indicate that even with the worst-case assumptions for EV electricity supply (100% natural gas), vehicle electrification can deliver substantial health benefits in the GTHA, equivalent to reductions of about 50 and 260 premature deaths per year for 25% and 100% EV penetration, compared to the base case scenario. If EVs are charged with renewable energy sources only, then electrifying all passenger vehicles can prevent 330 premature deaths per year, which is equivalent to $3.8 Billion (2016$CAD) in social benefits. When the benefit of EV deployment is normalized per vehicle, it is higher than most incentives provided by the government, indicating that EV incentives can generate high social benefits.