Interactive effects of nanoplastics, multi-contaminants, and environmental conditions on prairie aquatic ecosystems: A factorial composite toxicity analysis within a Canadian context.

Limited data exist on the interactions between nanoplastics (NPs) and co-contaminants under diverse environmental conditions. Herein, a factorial composite toxicity analysis approach (FCTA) was developed to analyze the time-dependent composite effects of NPs (0 ∼ 60 mg/L), copper (Cu, 0.2 ∼ 6 mg/L) and phenanthrene (PHE, 0.001 ∼ 1 mg/L) on microalgae under diverse pH (6.7 ∼ 9.1), dissolved organic matter (DOM, 1.5 ∼ 25.1 mg/L), salinity (1 ∼ 417 mg/L) and temperature (23 ∼ 33 °C) within the Canadian prairie context. The toxic mechanism was revealed by multiple toxic endpoints. The combined toxicity of NPs, Cu and PHE within prairie aquatic ecosystems was assessed by the developed FCTA-multivariate regression model. Contrary to individual effects, NPs exhibited a promotional effect on microalgae growth under complex environmental conditions. Although Cu and PHE were more hazardous, NPs mitigated their single toxicity. Environmental conditions and exposure times significantly influenced the main effects and interactions of NPs, Cu and PHE. The synergistic effect of NPs*Cu and NPs*PHE on microalgae growth became antagonistic with increased pH or DOM. Microalgae in the Souris River, Saskatchewan, were projected to suffer the most toxic effects. Our findings have significant implications for the risk management of NPs.

Toxicity and mechanism of nanoplastics to phytoplankton in high-latitude aquatic ecosystems of Canadian prairie: Effects of multiple environmental factors.

The potential ecological risks of nanoplastics (NPs) may be inaccurately assessed in some studies as they fail to consider the impact of environmental factors and their interactive effects. Here, the effects of six representative environmental factors (N, P, salinity, DOM (dissolved organic matter), pH and hardness) on NPs' toxicity and mechanism to microalgae are investigated based on the surface water quality data in Saskatchewan watershed, Canada. Our 10 sets of 26-1 factorial analysis reveal the significant factors and their interactive complexity towards 10 toxic endpoints from cellular and molecular levels. This is the first time to study the toxicity of NPs to microalgae under interacting environmental factors in high-latitude aquatic ecosystems of Canadian prairie. We find that microalgae become more resistant to NPs in N-rich or higher pH environments. Surprisingly, with the increase of N concentration or pH, the inhibitory effect of NPs on microalgae growth even became a promotion effect with the decreased inhibition rate from 10.5 % to -7.1 % or from 4.3 % to -0.9 %, respectively. Synchrotron-based Fourier transform infrared spectromicroscopy analysis reveals that NPs can induce alterations in the content and structure of lipids and proteins. DOM, N*P, pH, N*pH and pH*hardness have a statistically significant effect on NPs' toxicity to biomolecular. The toxicity levels of NPs across Saskatchewan watersheds are evaluated and we find that NPs could have the greatest inhibition on microalgae growth in Souris River. Our findings indicate that multiple environmental factors should be considered during the ecological risk assessment of emerging pollutants.

Rethinking the effects of micro/nanoplastics from the global environmental change and systematic perspective: An aquatic environmental system-based comprehensive assessment approach of micro/nanoplastic impacts.

The study on micro/nanoplastic pollution should embrace complexity. Here, we aim to develop an aquatic environmental system-based comprehensive assessment approach of micro/nanoplastic impacts (ACAM) to evaluate the effects of micro/nanoplastics on aquatic ecosystems from the global environmental change (GEC) and systematic perspective. A case study for freshwater systems in Saskatchewan, Canada was conducted to evaluate the comprehensive effects of multiple GEC factors (polystyrene-nanoplastics (PS-NPs), N, P, salinity, dissolved organic matter (DOM), pH, hardness) on Asterococcus superbus based on ten ecologically relevant endpoints. It is found that at the cellular level, PS-NPs and N had an antagonistic interaction on microalgal growth in the Saskatchewan freshwater ecosystem; at the molecular level, the PS-NP-induced changes in lipid composition in microalgae were regulated by P, DOM, and pH. The significance ranking of factor effects suggested that instead of PS-NPs pollution, the fluctuations in pH level, DOM and N concentrations should be paid attention to first in Saskatchewan. Under the combined impact of PS-NPs and other GEC factors, microalgae at station 14 (Qu'Appelle River near highway 56) might have the minimum growth rate with [-0.048, 0.094] d-1 in Saskatchewan. These findings demonstrate the efficacy of the developed ACAM in a more comprehensive and context-specific assessment of MNP risks, providing new insight for the management of MNP pollution.

Multi-regional industrial wastewater metabolism analysis for the Yangtze River Economic Belt, China.

Enormous wastewater discharges have significantly impeded the sustainable development. As several economic belt has been formed in China, systematic analysis of multi-regional wastewater metabolic system is required for advancing wastewater mitigation effectively and efficiently. In this study, a distributive environmental input-output model (DEIO) is developed for the Yangtze River Economic Belt (YREB) to provide bases for supporting sustainable development from inter-regional and inter-sectoral perspectives. The discharges and flows of wastewater and related pollutants (i.e., chemical oxygen demand (COD) and ammonia nitrogen (AN)) among sectors and regions are analyzed to providing solid bases for wastewater management within the YREB. The results show that the industrial wastewater mitigation in YREB is desired urgently. The industrial wastewater discharges in Jiangsu and Zhejiang provinces are numerous, while Hunan and Yunnan provinces are more inclined to suffer from serious COD and AN pollution. In addition, the manufacture of food, tobacco, chemical materials, and pharmaceutical are the typical sectors with a large amount of direct wastewater discharge, and the tertiary industry is ranked at the first in indirect wastewater discharge. According to the analysis, the implementation of the "Supply-side Structure Reform" and the "Replace Subsidies with Rewards" policy can benefit the wastewater mitigation in the YREB.

Toxic effect and mechanism of ultrafine carbon black on mouse primary splenocytes and two digestive enzymes.

This paper investigated the toxic effect and mechanism of ultrafine carbon black (UFCB) on splenocytes and enzymes in the digestive system. It was found that the toxicity of UFCB to splenocytes was dose-dependent. UFCB with a low concentration (<15 µg/mL) had no significant effect on splenocytes while UFCB with high concentration (>15 µg/mL) induced significant oxidative damage with increased content of reactive oxygen species (ROS) (134%) and malonaldehyde (MDA) (222.3%) along with the decreased activity of superoxide dismutase (SOD) (55.63%) and catalase (CAT) (87.73%). Analysis combined cellular and molecular levels indicated that UFCB induced splenocyte toxicity through oxidative stress. The interactions of UFCB with two important digestive enzymes, α-amylase and lipase, were also studied respectively. Results showed that the interaction of UFCB and the two enzymes altered the particle size and fluorescence intensity in both experimental systems. The formation of protein corona also resulted in the contraction of the polypeptide skeleton in both enzymes, which further inhibited their activity. Our work provided basic data on the toxicity of UFCB in the spleen and digestive system and fills the gap in the study of UFPs toxicity. CAPSULE: UFCB induced splenocyte toxicity and enzyme dysfunction through oxidative stress and protein corona formation respectively.

Cytotoxicity of perfluorodecanoic acid on mouse primary nephrocytes through oxidative stress: Combined analysis at cellular and molecular levels.

Long-chain perfluoroalkyl acids (PFAAs) such as perfluorodecanoic acid (PFDA) are toxic, persistent organic pollutants. This study investigated the harmful effect of PFDA on mouse primary nephrocytes and its mechanism at cellular and molecular levels. Cellular results showed that PFDA exhibited nephrotoxicity with decreased cell viability and increased apoptosis. The increase of intracellular reactive oxygen species (ROS) content and the decrease of intracellular superoxide dismutase (SOD) activity were significant (p < 0.01) when PFDA concentration exceeded 10 µM. Additionally, the molecular results indicated that PFDA bind with Val-A98 in the surface of Cu/Zn-SOD by a 3.11 Šhydrogen bond driven by Van der Waals' force and hydrogen bonding force, which triggered the structural changes and decreased activity of Cu/Zn-SOD. Altogether, the intracellular oxidative stress is the main driver of nephrocyte apoptosis; and the interaction of PFDA and Cu/Zn-SOD exacerbated the oxidative stress in nephrocytes, which is also a nonnegligible reason of cytotoxicity induced by PDFA. This study represented a meaningful method to explore the toxic effect and mechanism of xenobiotics at cellular and molecular levels. The findings have implications for revealing the clearance of long-chain PFAAs in vivo.

Membrane biofouling retardation by zwitterionic peptide and its impact on the bacterial adhesion.

Nanofiltration polyamide membranes naturally tend towards biofouling, due to their surface physicochemistries. Nisin, a type of short cationic amphiphilic peptide with antimicrobial properties, has been recognized as a safe antimicrobial for food biopreservation and biomedical applications. This study investigates the impact of nisin on the initial bacterial attachment to membranes, its anti-biofouling properties, and characterizes a non-monotonic correlation between nisin concentration and biofilm inhibition. Nisin was found to inhibit B. subtilis (G+) and P. aeruginosa (G-) attachment to both the nanofiltration membrane and the PES membrane. To determine the mechanism of action, we investigated the polysaccharides, protein, and eDNA as target components. We found that the quantities of polysaccharides and eDNA were significantly changed, resulting in bacterial death and anti-adhesion to membrane. However, there were no discernable impacts on protein. We postulated that nisin could prevent irreversible biofouling by decreasing adhesion, killing bacteria, and reducing biofilm formation. We examined membrane flux behavior through bench-scale cross-flow experiments at a set concentration of nisin (100 µg mL-1), with membrane behavior being confirmed using CLSM images. Results showed that nisin could enhance anti-biofouling properties through both anti-adhesive and anti-bacterial effects, and therefore could be a novel strategy against biofouling of membranes.