Environmental Water Pollution Research Articles

Design and synthesis of black phosphorus quantum dot sensitized inverse opal TiO2 photonic crystal with outstanding photocatalytic activities

Quantum dot sensitized photocatalyst is designed and applied in purification of dye wastewater, using black phosphorus nanoparticles (BPQDs) as the quantum dot and inverse opal (IO) TiO2 photonic crystal as the main photocatalyst. Due to electron density change within the composite, electrons can transfer from BPQDs to IO TiO2 directionally. Bandgap energies and relative energy band positions of BPQDs and IO TiO2 further provide efficient electronic transmission channels at the heterojunction interface. Therefore, interfacial resistance for charge transfer is reduced, the production of active oxidative species is promoted, and the photo induced charge transfer proceeds through a typical type-II route. Finally, excellent photocatalytic properties of BPQDs-IO TiO2 are achieved with the highest apparent kinetic constant (kapp) of 0.046 min−1, which is more than 3 times for bare IO TiO2 (0.014 min−1) and nearly 2 times for commercial P25 TiO2 (0.027 min−1). Furthermore, long-term stability and non-toxicity make the quantum dot sensitized photocatalyst have great applications in purifying environmental water pollution.

Analysis on the Impact of River Basin Ecological Compensation Policy on Water Environment Pollution

The implementation of the river basin ecological compensation policy (ECP) is an important way to improve the ecological environment and achieve the goal of “beautiful China” (“Beautiful China” is a concept put forward by the 18th National Congress of the Communist Party of China.). The impact analysis of the watershed ecological compensation policy provides an important basis for improving the mechanism. The research regards the Dawen River Basin ecological compensation policy in Shandong Province as a natural experiment and uses the 2005–2017 prefecture-level city panel data. Based on the two-way panel fixed effect model, Propensity Score Matching and Differences-in-Differences (PSM-DID) are applied to analyze the mechanism of the Dawen River Basin ECP pilot project and its impact on the intensity of water pollution, in order to provide experience for the development of ecological compensation work in the Yellow River Basin in the future. The empirical results show that the implementation of the river basin ECP has significantly reduced the intensity of water pollution by 22.47% with a short time lag, and the pollution reduction effect of the policy is increasing year by year. The river basin ECP has an obvious optimizing effect on industrial structure, with an inconspicuous effect on economic growth and technological progress. Finally, relevant policy recommendations are put forward from the aspects of the promotion, implementation and effect of the river basin ECP.

An ultra sensitive and rapid SERS detection method based on vortex aggregation enhancement effect for anti-infective drug residues detection in water

The environmental pollution and human health risks caused by anti-infective residual drugs in the environment have attracted much attention. More convenient and effective detection methods to achieve the rapid and high sensitivity detection for such pollutants are required. In this work, a novel surface-enhanced Raman scattering (SERS) strategy based on vortex aggregation of AgNPs was proposed for the detection of anti-infective drugs in environmental water. The method enhanced the Raman signal of the targets by 2–7.4 times. The mechanism of aggregation enhancement effect under the low-frequency oscillation procedure which significantly enhanced the SERS signal of targets molecular on the aggregated AgNPs was revealed by UV–vis and ICP-MS methods. Three drugs of cefazolin sodium, pefloxacin, and chloroquine phosphate were determined. The detect limits were 3.97 × 10−9 mol/L, 2.42 × 10−10 mol/L, and 7.34 × 10−9 mol/L for cefazolin sodium, pefloxacin, and chloroquine phosphate, respectively. The quantitative relationships were obtained in a wide linear range of 4–5 orders as well as good accuracy and stability with the recoveries of 84.0%–97.1% and the relative standard deviations (RSDs) less than 4.6% for spiked in actual water samples. This method also had excellent repeatability and stability, which have potential application for rapid detection of trace pollutants in water environment.

Solid-liquid interface adsorption of antibiotic resistance plasmids induced by nanoplastics aggravates gene pollution in aquatic ecosystems

Antibiotic resistance genes (ARGs) and nanoplastics (NPs) have been identified as emerging pollutants in water environment; the interactions between antibiotic resistance plasmids (ARPs) and NPs will influence ARG transport in sediments. Herein, the adsorption experiments of a typical ARP onto polystyrene nanoplastics (PS-NPs) in river and lake sediments were conducted to elucidate the adsorption mechanisms and the effects of environmental factors. Results indicated that the adsorption amounts of PS-NPs increased with the dosages while decreased with the particle size of sediments. Multi-layer adsorption of PS-NPs was found to exist mainly in sand and silt sediments, whereas the filling adsorption dominated in the clay. Moreover, the adsorbed PS-NPs enhanced the physisorption of ARPs in sediments through stimulating the intraparticle diffusion of ARPs induced by electrostatic force. Besides, the adsorption amounts of ARPs onto the PS-NPs decreased with the increasing pH and dissolve organic matter due to the enhanced electrostatic repulsion and competitive adsorption. The ion strength played catalytic roles by increasing the electrostatic attraction and adsorption sites of ARPs on PS-NPs. The adsorbed ARPs in sediments were closely related with the ARGs in extra/intracellular DNA of biofilms, influencing the distribution and proliferation of ARGs largely. The findings indicate that ARG-associated pollution might be enhanced by the solid-liquid interface adsorption induced by NPs, which was controlled by pH, ion strength and dissolve organic matter. This study provides supplementary insights into the roles of NPs as carriers of ARP in sediments, and advances our understanding on the risks of NP-ARG co-occurring contamination in aquatic ecosystems.

Durable, strong, and flexible superhydrophobic N-TiO2 silicone composite aerogels with unique air–liquid–solid triphase photocatalytic properties

TiO2 nanoparticles are promising photocatalysts for the remediation of water pollution. However, the difficulty in recycling and low light absorption of powder TiO2 hinder their application in photocatalysis. Although some studies have attempted to address these problems by immobilizing TiO2, the application of traditional immobilized TiO2 in water environment is limited because of their unstable immobilization, poor mechanical strength, low light utilization, high electron-hole recombination,and unsatisfactory photocatalytic performance. In this study, flexible superhydrophobic Nitrogen-doped TiO2 (N-TiO2) silicone composite aerogels were achieved by copolymerization of γ-methacryloxypropyl trimethoxy silane (KH570)-grafted N-TiO2 with methyltrimethoxysilane and dimethoxydimethylsilane. These flexible composite aerogels possess improved mechanical strength and stable immobilization of N-TiO2. Moreover, an air–liquid–solid triphase photocatalytic interface was formed by the superhydrophobic surface of composite aerogel, solution and the air layer existed between them. This triphase photocatalytic interface enabled oxygen at the reaction interface to be directly and rapidly supplied from the air layer, thus photogenerated electrons from the photocatalyst surface can be effectively removed and the recombination of electron holes can be reduced. Besides, the flexible photocatalyst was molded into water grass shape and placed in a water channel to verify its photodegradation efficiency and durability under hydrodynamic conditions. Experimental results confirmed that the proposed flexible photocatalyst with a triphase catalytic interface has application prospects for the degradation of pollutants in water environment.

Evolution and Ecological Implications of Land Development and Conservation Patterns on the Qinghai-Tibet Plateau

The Qinghai-Tibet Plateau serves as an important ecological security shelter in China and across Asia. During the past two decades, the patterns of land development and conservation on the Qinghai-Tibet Plateau have undergone significant changes under the impacts of global climate change and human expansion. This paper analyzes the evolution of land development and conservation patterns and potential ecological implications on the Tibetan Plateau from 2000 to 2020 based on urbanization, agricultural and pastoral patterns with multi-source data, such as long-term time series land use data, ecological indices, environmental pollution, and population and economics. It was found that: (1) Coinciding with the agglomeration of population and economy, the urban development pattern on the Qinghai-Tibet Plateau has spatial-temporal differentiation. Urban development in the 2010s was more significant than that in the 2000s, with the intensity increased by 63.31%, and the development pattern varies spatially, which can be seen from the finding that central Tibet (the Yarlung Tsangpo, Lhasa river, and Nyangchu basins) and Huangshui River Basin in Qinghai Province were developed in a planar pattern, while other node cities and border towns in a dotted pattern. (2) The agricultural production pattern is relatively stable, the grain yields have increased by 34.68% in the past 20 years, but the total amount of arable land is shrinking, and the degree of fragmentation has increased. The pattern of pastoralism has changed greatly, showing a migration trend from west to east spatially, and there is a serious problem of pasture overload, with an increase of 18.4% in livestock products. Regardless of the pattern of urbanization or agricultural and livestock development, the intensity of human activities on the Qinghai-Tibet Plateau has shown an intensified trend in the past. (3) It shows that Lhasa City area and the middle and lower reaches of Huangshui show a trend of diffusion of atmospheric and water environmental pollution. The western part of the Ali region and the northern foothills of the Himalayas and other regions, under the combined impact of climate change and human activities, have undergone significant ecological degradation. Accordingly, this paper proposes policy recommendations for optimizing production and living space, advancing the establishment of national park clusters and nature reserve systems, and the integrated recovery of mountain, water, forest, lake, grass, sand, and ice with ecological value achievement.

Effect of Microbes in Enhancing the Composting Process: A Review

The increase in global population and the resulting economic activity have led to major environmental problems such soil, air, and water pollution. This rise in population growth has resulted in increased use of chemical fertilizers to boost agricultural production resulting in loss of microbiological and physicochemical equilibrium of soil. These factors have led to an increased need for eco-friendly agricultural products that help to enhance the soil's physical, chemical, and microbiological characteristics and, in turn, provide nutrients for plants. Composting has emerged as the preferred method for treatment of organic wastes in order to produce a final, sterilized product that can be used as an organic amendment. Different organic substances are converted into more stable molecules during the aerobic, microorganism-mediated, solid-state fermentation process known as composting. One effective strategy for accelerating the biotransformation of organic materials during the composting process is microbial inoculation. The inclusion of microorganisms could improve the composting process by speeding up the decomposition of organic matter, mineralization, and the activities of microbial enzymes, as well as the quality of the finished products. This review will give a brief idea about the composting process, quality of compost and the most recent strategies for enhancing the composting process mainly with the help of microbes.

Concentrations, bioaccumulation, and health risk assessments of heavy metals in fishes from Nigeria's freshwater: a general overview.

Heavy metals (HMs) have attracted global attention due to their toxicity, persistence, and accumulation in aquatic fish in the polluted water environment. The consumption of these fishes exposed humans to a higher risk of non-carcinogenic and carcinogenic risks. In this study, we provided a critical overview of the potential sources and concentration of HMs in Nigeria's freshwater. Furthermore, we reported their pollution level in widely eaten fish species in the country. Our findings show that effluent from anthropogenic and industrial activities is one of the major sources HMs in the country. The mean concentration of Zn (9.02 mg/L), As (7.25 mg/L), Cu (4.35 mg/L), Fe (1.77 mg/L), and Pb (1.46 mg/L) in Nigeria's freshwaters were found to be high than Nigerian Standard for Drinking Water Quality permissible limit. This study demonstrated considerable health risks associated HMs via dietary consumption of different fishes from polluted waters. Therefore, we recommended an urgent need for effective management HMs in water bodies in order to protect the lives of people living in the country.

Identification and Structure-Activity Relationship of Recovered Phenolics with Antioxidant and Antihyperglycemic Potential from Sugarcane Molasses Vinasse.

Sugarcane molasses vinasse is the residue of the fermentation of molasses and the water and soil environmental pollutants from distilleries. However, its recycling value has been neglected. The chemical analysis of the molasses vinasse led to the isolation of a new benzoyl chloride called 2,3,4-trihydroxy-5-methoxy benzoyl chloride, as well as thirteen known compounds, including six benzoic acids. The structure of the new benzoyl chloride was elucidated on the basis of extensive spectroscopic analysis. The antioxidant activity of all isolated compounds was measured using the ORAC assay. Moreover, we compared the cellular antioxidant activity (CAA) and inhibitory activity against α-amylase and α-glucosidase for structure–activity analysis. The results showed that only vanillic acid had CAA (8.64 μmol QE/100 μmol in the no PBS wash protocol and 6.18 μmol QE/100 μmol in the PBS wash protocol), although other benzoic acid derivatives had high ORAC values ranging between 1879.9 and 32,648.1 μmol TE/g. Additional methoxy groups at the ortho-positions of the p-hydroxy group of benzoic acids enhanced the inhibition of α-glucosidase but reduced the ORAC activity unless at the para-position. This work indicated that phenolics, especially phenolic acids in the sugarcane molasses vinasse, possessed potential antioxidant and antihyperglycemic activity, which improved the utilization rate of resources and reduced the discharge of pollutants.

Effect of live and inactivated Chlamydomonas reinhardtii on the removal of tetracycline in aquatic environments

With the development of medical drugs, the widely used tetracycline has brought many adverse effects on the ecosystem and human health. Tetracycline pollution of water environment is becoming more and more serious, and has become an emerging environmental problem. As single celled organisms, microalgae are not only model organisms for risk assessment of aquatic ecosystems, but also can efficiently purify sewage. Microalgae-mediated pollutant remediation has attracted more and more attention from researchers. In this paper, Chlamydomonas reinhardtii (C. reinhardtii) was used to remove tetracycline in aqueous solution, and the removal efficiency and mechanism of microalgae on tetracycline were studied. The results showed that the removal rates of tetracycline by active and inactivated microalgae at a density of 5 × 106 cells·mL−1 were 81.9% and 89.8%, respectively. C. reinhardtii removed tetracycline through biosorption and nonmetabolic processes. Microalgal cell supernatant and hydroxyl radicals could significantly promote the removal of tetracycline. The positively charged tetracycline was electrostatically adsorbed on the microalgae surface and extracellular polymeric substances. Microalgae biomass can promote the production of ROS and enhance the ability of microalgae to remove tetracycline.

Phytoremediation Process of Water Spinach (Ipomoea aquatica) in Absorbing Heavy Metal Concentration in Wastewater

Heavy metals have become one of the environmental pollutants in water. To overcome this problem, the phytoremediation process was used as the method to cleanse polluted media. The objectives of the study are to determine the heavy metal accumulation by water spinach (Ipomea aquatica) in different types of heavy metal and to determine the level of heavy metal reduction in contaminated water. Ipomea aquatica was placed in containers that had solutions of different heavy metal concentrations. The selected heavy metals are cadmium (Cd), zinc (Zn), and copper (Cu), with a concentration of 5 ppm, 10 ppm, and 15 ppm, respectively. This study lasted about 20 days. Every four days, plant and water samples are collected. The plant samples were dried, digested, and analyzed by using ICP-OES. The two-way ANOVA statistical test was used to measure the differences in the amounts of the heavy metals accumulated in the plant and water. The accumulation of elements in plants shows a gradual increase in the uptake of cadmium, Cu, and Zn. Ipomea aquatica is suitable to take up cadmium, where the highest level of cadmium found was 13.99 mg/kg. On day 8, the level of heavy metals in the water gradually decreases for Cu and Zn. The presence of heavy metals in the water had decreased by 82.20 % on the last day of treatment. Ipomea aquatica accumulated more heavy metals while the number of heavy metals in the water decreased over a period of days. For all heavy metal types, significant differences in heavy metal concentration were obtained at p<0.05, showing that Ipomea aquatica can be used in the phytoremediation approach to remove heavy metals from wastewater.

An unexpected synergistic toxicity caused by competitive bioconcentration of perfluoroalkyl acid mixtures to Daphnia magna: Further promoted by elevated temperature

The mixed pollution of the global water environment by perfluoroalkyl acids (PFAAs) and their ecological risks have aroused widespread concern. However, the relationship between the combined toxicity of PFAA mixtures and their accumulation in aquatic organisms is not well understood in the context of global warming. Here, we study the bioconcentration and combined toxicity of three PFAA mixtures (PFOA, PFDA, PFDoA) to Daphnia magna (D. magna) under different exposure concentrations and temperatures. The results show that although competitive bioconcentration exists, the combined toxicity of the PFAA mixtures to D. magna is synergistic. These contradictory phenomena occur because although the longer-chain PFDoA inhibits the bioconcentration of the shorter-chain PFOA and PFDA, the bioconcentration of PFDoA itself is promoted, and PFDoA is more toxic to D. magna than PFOA and PFDA. The toxic equivalent concentration for the PFAA mixture is 1.38–1.67 times higher than that obtained from simple addition for the three PFAAs when exposed separately. Moreover, elevated temperature promotes not only the bioconcentration of each PFAA and the competition of bioconcentration between shorter-chain and longer-chain PAFF, but also the synergistic toxicity of PFAA mixtures to D. magna. This study suggests that the effect of the interactions among different PFAAs on their bioconcentration and toxicity under different water environmental conditions, such as temperature, should be considered for ecological risk assessment of PFAA mixtures.

Hydrogeochemical Characteristics of a Multi-Layer Groundwater System in a Coal Mine Area: A Case Study

The Yanzhou coalfield is an important coal production base in north China, wherein a huge amount of mine drainage has occurred; however, there has been relatively little research on the multi-layer groundwater system. In this study, the Dongtan Coal Mine was considered as the research object and a total of 95 samples were collected. Furthermore, hydrogeochemical and statistical methods were employed to better understand the hydrogeochemical characteristics of the groundwater system in the Yanzhou coalfield. The results show that the groundwater in the area is alkaline. The Ordovician limestone aquifer is quite different from the other aquifers, and the karst herein shows regional distribution characteristics. During the hydrogeochemical evolution of the groundwater, more carbonate and sulfate dissoluted, more cation exchanged, and a lesser extent of silicate weathering and halite dissolution occurred. A conceptual hydrogeological model was created. It shows that the changes in the drainage conditions further resulted in the water chemistry being complex, and induced the hydrogeochemical evolution. The changes in the groundwater dynamic field and the hydrochemical field should be studied to better understand the evolution of the hydrogeochemical properties and accordingly make preparations for preventing mine water disasters and environmental pollution.

Recent advances in electrochemical sensor developments for detecting emerging pollutant in water environment.

In the latest times, considerable studies have been performed closer to detecting emerging pollutant such as paracetamol in wastewater. Electrochemical sensor developments have recently started to determine in fewer concentrations effectively. The detection of paracetamol using standard protocols corresponding to electroanalytical techniques has a greater impact noticed in directing the detecting process toward biosensors. Non-enzymatic sensors are the peak of all electro analysis approaches. Functionalized materials, such as metal oxide nanoparticles, conducting polymers, and carbon-based materials for electrode surface functionalization have been used to create a fortification for distributing passive enzyme-free biosensors. Synergic effects are possible by enhancing loading capacity and mass transfer of reactants for attaining high analytical sensitivity using a variety of nanomaterials with large surface areas. The main focus of this study is to address the prevailing issues in the identification of paracetamol with the tasks in the non-enzymatic sensors field, followed by the useful methods of electro analysis studies.

Evaluate cities' urban water resources system resilience along a river and identify its critical driving factors.

The emergence of a series of problems, such as serious water environment pollution and flood disasters, leads to an increase in an urban water resources system's vulnerability and pressure. In order to alleviate an urban water resources crisis, calculating the water resources system resilience (WRSR) and identifying its impact factors are essential. This paper constructed a resilience evaluation framework of the "Economy-Social Development-Infrastructure-Water Resources-Ecological Environment" water resources system from three stages, i.e. resistance, restoration and adaptability. Then, taking 21 cities along the Yangtze River Economic Belt's lower reaches (YREB's lower reaches) as an example, we scientifically measured the WRSR by using the Projection Pursuit Evaluation Model of Real Coding based on the Accelerating Genetic Algorithm (RAGA-PP) and analyzed its driving factors with Geographic Detectors (GD). (1) From 2010 to 2018, the overall level of the WRSR along the YREB's lower reaches was low, and it was characterized by attenuation from central cities to marginal cities; Suzhou had the highest average WRSR (0.656), while Chizhou had the lowest (0.207). (2) From stage characteristics, compared with 2010, resistance and restoration of most cities along the YREB's lower reaches showed an upward trend in 2018; however, the adaptability level of some cities was still low. From the perspective of sub-system resilience, resilience levels of different sub-systems in each urban water resources system (UWRS) were different. (3) For impact factors, average factor interpretations of per capita GDP, average wages of employees and affected areas of floods, geological disasters and typhoons were largest. Based on this, this paper provides relevant suggestions for improving the WRSR along the YREB's lower reaches to improve ability of UWRS to resist external risks.

Land use and cover change (LUCC) impacts on Earth’s eco-environments: Research progress and prospects

Land use and cover change (LUCC) is one of the key variables dominating land–atmosphere interactions and strongly affects the Earth’s eco-environments by altering surface properties. Numerous studies have been carried out to assess the impact of LUCC. However, the Earth is a large, open and complex system characterized by complex interactions between its eco-environments and drivers. This study aimed to summarize previous studies of the impact of LUCC on the Earth’s eco-environments and discuss the progress and limitations in suggesting future directions. Previous studies have confirmed that LUCC has a wide range of impacts on the Earth’s eco-environments, which are represented by the alternation of climate (temperature, precipitation, wind, and humidity), hydrology (soil moisture, runoff, and evapotranspiration), ecology and environmental (air, water, and soil) pollution. Physically, the impacts were mainly attributed to the disturbance of the surface radiation budget and matter conservation caused by LUCC. Although great achievements have been made, several challenges remain because of the unavoidable uncertainties in data sources and methodologies and the complexity of eco-environmental evolution. Therefore, data assimilation, physical-based investigations, contribution isolation, and full-process analysis are required to overcome these challenges in future research. The results of this study helped to capture the impact of LUCC and its physical mechanisms, which provide useful clues for future research and support the relative land use management for sustainable development.

Effects of dissolved black carbon bound with goethite on physicochemical properties and adsorption capacity for imidacloprid: Adsorption versus coprecipitation

Dissolved black carbon (DBC) is an important component of natural dissolved organic matter and can bind to iron minerals to form DBC-mineral complexes by adsorption and coprecipitation. However, reports regarding the difference in physicochemical properties between adsorbed and coprecipitated DBC-mineral complexes and their sorption capacity for polar organic pollutants are limited. Herein, goethite (Gt) and the adsorbed and coprecipitated complexes of DBC with Gt (SGt-DBC and CGt-DBC) were prepared, and their physicochemical properties and adsorption capacity for polar imidacloprid (IMI) were determined. The results showed that DBC could efficiently bind to Gt by coprecipitation or adsorption, leading to the aggregation of Gt particles, decreasing SSA, and increasing microporous volume, O-containing functional groups and negative charges. A greater effect was observed in CGt-DBC samples than SGt-DBC samples. CGt-DBC samples could more efficiently adsorb IMI than SGt-DBC samples, and CGt-DBC samples obtained the greatest Qmax with 68.4 mg/kg. The sorption mechanisms mainly involved hydrophobic partitioning, H-bonding, cation-π and p/π-π electron donor-acceptor interactions and electrostatic interactions. Additionally, the greater solution pH and Na+ concentration facilitated IMI adsorption on Gt and Gt-DBC samples; however, the Ca2+ solution obtained the opposite result. This effect on IMI adsorption was more pronounced for CGt-DBC samples. Therefore, the findings of this study provide a deep understanding of the interactions between Gt and DBC by adsorption and coprecipitation and their effect on the sorption of organic pollutants in natural soil and water environments.

A Review of Persulfate Activation by Magnetic Catalysts to Degrade Organic Contaminants: Mechanisms and Applications

All kinds of refractory organic pollutants in environmental water pose a serious threat to human health and ecosystems. In recent decades, sulfate radical-based advanced oxidation processes (SR-AOPs) have attracted extensive attention in the removal of these organic pollutants due to their high redox potential and unique selectivity. This review first introduces persulfate activation by magnetic catalysts to degrade organic contaminants. We present the advances and classifications in the generation of sulfate radicals using magnetic catalysts. Subsequently, the degradation mechanisms in magnetic catalysts activated persulfate system are summarized and discussed. After an integrated presentation of magnetic catalysts in SR-AOPs, we discuss the application of persulfate activation by magnetic catalysts in the treatment of wastewater, landfill leachate, biological waste sludge, and soil containing organic pollutants. Finally, the current challenges and perspectives of magnetic catalysts that activated persulfate systems are summarized and put forward.

The atmospheric microplastics deposition contributes to microplastic pollution in urban waters

Identifying and understanding the potential sources delivering microplastics into the urban water environment is imperative for microplastic pollution control. However, how atmospheric deposition contributes to microplastic pollution in the urban water environment is unclear. Therefore, this study investigated the contribution of atmospheric deposition to microplastic pollution in urban waters based on the analysis of the atmospheric deposition characteristics in the urban area. The results showed that microplastic deposition fluxes during wet weather and dry weather varied from 1.1 × 103±0.06×103 to 3.5 × 103±0.3 × 103 particles/m2/day and 0.91×103±0.09×103 to 1.6 × 103±0.1 × 103 particles/m2/day, respectively. The microplastics deposition flux showed moderate to strong correlations to atmospheric particulate matter concentrations, especially the PM2.5 concentration (R2 = 0.76–0.93), suggesting the regularly monitored PM2.5 concentration might be served as an indicator for microplastics deposition flux estimation. The deposited microplastics were mainly transparent fragments with an average size of 51–67 μm. Polyethylene and polypropylene were the most abundant plastic polymer, followed by polyethylene terephthalate and polyamide. The comparison of microplastics collected during different weather conditions suggested that rain events could increase microplastics deposition fluxes when air quality conditions are similar. Particularly, rains promoted the deposition of fibrous microplastics as well as smaller microplastics. The estimated daily microplastics deposition in the whole city region suggested more microplastics were deposited in summer and winter. The total quantity of microplastics deposited in the urban environment could reach 1.7–12 times of those discharged from treated wastewater. Among them, 10% would directly deposit to urban waters in the studied city region, while the others may also enter the urban waters through runoff. The results of this study highlighted that the atmospheric microplastics deposition is an important source for microplastics, especially smaller ones, to enter the urban waters, which could not be ignored during microplastics pollution control.

Future Perspective for Utilization of Municipal Solid Waste (MSW) in India: A Review

Presently urban areas are reported for supporting 56% of the total world population, accountable for generating significant amount of municipal solid waste (MSW). Seventy percent of which ends into landfills, 19% is recycled and 11% is employed for energy generation. Generation of municipal solid waste in India is increasing day by day. The average per capita generation of waste was about 500 g/day in 2007 and it will increase to 925 g/day by 2047. Municipal solid waste (MSW) is one of the key components of India’s prominent mission ‘Swachh Bharat Abhiyan’. Rising urbanization, faster economic growth and lifestyle changes all contribute to higher waste generation in India. Unscientific treatment, improper collection and low use of technology based solutions for handling MSW lead to hazards like environmental degradation, water pollution, air pollution and soil pollution. The most important step to be used for management of this waste would be minimising its generation but this is not really possible. Then to manage waste sustainably, the waste to wealth route remains a viable solution although in India it is not common practice. Maximum recycling, composting with organic municipal solid waste and waste to energy generation should be utilised for MSW management. This approach of sustainable waste management can solve the problem of land required for waste disposal and resulting pollution problems of air, ground, surface water, soil etc.