Transport Of Other Pollutants Research Articles

Fluorescence spectroscopic characterization of dissolved organic matter in the wastewater treatment plant and hybrid constructed wetlands coupling system in winter: A case study in eastern China

Dissolved organic matter (DOM) in municipal wastewater can have a detrimental effect on aquatic ecosystems, as DOM can participate in the global carbon cycle and change the transport of other pollutants. The characteristics of DOM can also affect the utilization efficiency of dissolved organic carbon by microorganisms in water. In this study, variations in DOM quantity and quality in a full-scale wastewater treatment plant (WWTP) coupled with a hybrid constructed wetland (CW) system during cold periods were characterized by using excitation-emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC). The results showed that the DOM concentration significantly decreased after exiting the WWTP, while a slight increase was found in the CW. The coupled system could significantly eliminate influent DOM with a removal efficiency of 92.1%. The CW system could still remove DOM even in winter. Five fluorescent components, including three humic-like components, one protein-like component and one tyrosine-like component, were identified. Although the biological treatment process in the WWTP contributed a large number of protein-like substances, the optical indices showed that the bioavailability of wastewater was gradually reduced, indicating that DOM was selectively removed by the integrated system. Moreover, there were significant correlations between water quality parameters and DOM indices. This study could contribute to a better understanding of the elimination process of dissolved organic carbon in coupled systems of WWTPs and CWs and offer novel ideas for organic carbon resource recovery and water quality monitoring in watershed environments.

Competitive adsorption of lead and cadmium onto nanoplastics with different charges: Two-dimensional correlation spectroscopy study.

The competitive adsorption ability and mechanisms of lead (Pb2+) and cadmium (Cd2+) by nanoplastics (NPs) with positive charges (PS-NH2) and negative charges (PS-SO3H) were investigated by using batch adsorption experiments coupled with the two-dimensional correlation spectroscopy (2D-COS) method. The adsorption isotherm results showed that PS-SO3H exhibited a higher adsorption capacity for Pb2+ or Cd2+ compared to PS-NH2. The adsorption affinity of NPs for Pb2+ was higher than that of Cd2+. The competitive adsorption results showed that Pb2+ had a more pronounced negative effect on the adsorption of Cd2+. The adsorption capacities of NPs were affected by the surface charge and solution pH. Electrostatic force was the main factor influencing PS-SO3H to capture Pb2+ and Cd2+, while chelation was the main mechanism between PS-NH2 and metals. The functional groups of NPs played significant roles in the sorption of Pb2+ or Cd2+ according to the FTIR spectra and 2D-COS analysis. This study provided new insights into the impact of NPs on the transport of other pollutants.

Polystyrene microplastic particles in combination with pesticides and antiviral drugs: Toxicity and genotoxicity in Ceriodaphnia dubia

Freshwater ecosystems are recognized as non-negligible sources of plastic contamination for the marine environment that is the final acceptor of 53 thousand tons of plastic per year.In this context, microplastic particles are well known to directly pose a great threat to freshwater organisms, they also indirectly affect the aquatic ecosystem by adsorbing and acting as a vector for the transport of other pollutants (“Trojan horse effect”). Polystyrene is one of the most widely produced plastics on a global scale, and it is among the most abundant microplastic particles found in freshwaters. Nevertheless, to date few studies have focused on the eco-genotoxic effects on freshwater organisms caused by polystyrene microplastic particles (PS-MPs) in combination with other pollutants such as pharmaceuticals and pesticides.The aim of this study is to investigate chronic and sub-chronic effects of the microplastic polystyrene beads (PS-MP, 1.0 μm) both as individual xenobiotic and in combination (binary/ternary mixtures) with the acicloguanosine antiviral drug acyclovir (AC), and the neonicotinoid broad-spectrum insecticide imidacloprid (IMD) in one of the most sensitive non-target organisms of the freshwater food chain: the cladoceran crustacean Ceriodaphnia dubia. Considering that the individually selected xenobiotics have different modes of action and/or different biological sites, the Bliss independence was used as reference model for this research. Basically, when C. dubia neonates were exposed for 24 h to the mixtures during Comet assay, mostly an antagonistic genotoxic effect was observed. When neonates were exposed to the mixtures for 7 days, mostly an additive chronic toxic effect occurred at concentrations very close or even overlapping to the environmental ones ranging from units to tens of ng/L for PS-MPs, from tenths/hundredths to units of μg/L for AC and from units to hundreds of μg/L for IMD, revealing great environmental concern.

Post COVID-19 pandemic: Disposable face masks as a potential vector of antibiotics in freshwater and seawater

With the outbreak and widespread of the COVID-19 pandemic, large numbers of disposable face masks (DFMs) were abandoned in the environment. This study first investigated the sorption and desorption behaviors of four antibiotics (tetracycline (TC), ciprofloxacin (CIP), sulfamethoxazole (SMX), and triclosan (TCS)) on DFMs in the freshwater and seawater. It was found that the antibiotics in the freshwater exhibited relatively higher sorption and desorption capacities on the DFMs than those in the seawater. Here the antibiotics sorption processes were greatly related to their zwitterion species while the effect of salinity on the sorption processes was negligible. However, the desorption processes were jointly dominated by solution pH and salinity, with greater desorption capacities at lower pH values and salinity. Interestingly, we found that the distribution coefficient (Kd) of TCS (0.3947 L/g) and SMX (0.0399 L/g) on DFMs was higher than those on some microplastics in freshwater systems. The sorption affinity of the antibiotics onto the DFMs followed the order of TCS > SMX > CIP > TC, which was positively correlated with octanol-water partition coefficient (log Kow) of the antibiotics. Besides, the sorption processes of the antibiotics onto the DFMs were mainly predominated by film diffusion and partitioning mechanism. Overall, hydrophobic interaction regulated the antibiotics sorption processes. These findings would help to evaluate the environmental behavior of DFMs and to provide the analytical framework of their role in the transport of other pollutants.

Transport and transformation of microplastics and nanoplastics in the soil environment: A critical review

AbstractSoil pollution by microplastics (MPs, 0.1 μm ~ 5 mm) and nanoplastics (NPs, ≤0.1 μm) has drawn much attention in recent years due to its potential ecological and human health risks; however, there are very limited studies and a general lack of consensus regarding the transport and transformation of MPs/NPs in soil environment. This review critically discusses the environmental behaviour of soil MPs/NPs, including the homo‐aggregation or hetero‐aggregation with other particles, sorption of pollutants and the photoaging process. The physicochemical property change of aggregated and aged MPs and its effect on the transport of other pollutants in soil has also been reviewed. Critical factors that affect the fate of MPs/NPs, including the physicochemical properties of MPs/NPs, physicochemical properties of soil and environmental factors, are reviewed to understand the latest progress in the environmental behaviour of soil MPs. Finally, we identify important research gaps, which include standard uniformity of quantification method, transformation mechanism elucidation and long‐term field studies. The review provides an overview of current findings for transport and transformation of MPs/NPs in natural soil environment and gives comments for future work.

Microplastics and Nanoplastics in Aquatic Environments: Aggregation, Deposition, and Enhanced Contaminant Transport.

Plastic litter is widely acknowledged as a global environmental threat, and poor management and disposal lead to increasing levels in the environment. Of recent concern is the degradation of plastics from macro- to micro- and even to nanosized particles smaller than 100 nm in size. At the nanoscale, plastics are difficult to detect and can be transported in air, soil, and water compartments. While the impact of plastic debris on marine and fresh waters and organisms has been studied, the loads, transformations, transport, and fate of plastics in terrestrial and subsurface environments are largely overlooked. In this Critical Review, we first present estimated loads of plastics in different environmental compartments. We also provide a critical review of the current knowledge vis-à-vis nanoplastic (NP) and microplastic (MP) aggregation, deposition, and contaminant cotransport in the environment. Important factors that affect aggregation and deposition in natural subsurface environments are identified and critically analyzed. Factors affecting contaminant sorption onto plastic debris are discussed, and we show how polyethylene generally exhibits a greater sorption capacity than other plastic types. Finally, we highlight key knowledge gaps that need to be addressed to improve our ability to predict the risks associated with these ubiquitous contaminants in the environment by understanding their mobility, aggregation behavior and their potential to enhance the transport of other pollutants.