Current Pollution Reports最新文献

Purpose of Review

Constructed wetlands (CWs) are engineered systems that have been proven as an alternative option to traditional wastewater treatment technologies because of their ability to provide cost-effective and energy-efficient solutions. This technology depends on natural microbial/biological, physical, and chemical processes to treat wastewater. Processes removing impurities in constructed wetlands are based on the combination of interactive systems such as selected plant species, the nature of substrate used for constructed wetlands, biofilm growth, microbial diversity, and several biogeochemically affected reaction cycles in wetland systems. Microorganisms play a vital role in these processes such as the degradation of pollutants and the transformation of nutrients. Microorganisms remove the pollutants from CWs by catalyzing chemical reactions, biodegrading, biosorbing, and supporting plant growth. An in-depth analysis of the function of microorganisms in CWs is important to understand. This review deals with the recent developments in constructed wetland systems from a microbiological perspective to treat impurities present in wastewater. It focuses on the studies of microbial diversity in CWs and the role of enzymes produced by microbes, the influence of the substrates of CWs on microbial diversity, the influence of the hydraulic design of CWs on the growth of microorganisms, the role of specific microbes in the removal of pollutants and the different software, analytical equipment, tools, and techniques used to measure/quantify the parameters of interest or to design and operate a wetland.

Recent Findings

The combination of different types of substrates in constructed wetlands can form different types of zones such as anaerobic and aerobic zones which can allow to form a diversity of microorganisms. In addition, plant diversity plays a vital role in microbial growth by providing O₂ and increasing plant biomass production which influences the soil microbial community. Moreover, the influent carbon source influences the biomass as for example when the COD/N ratio is increased by 80%, the phospholipid fatty acids (PLFA) concentration of microbial biofilm in glucose constructed wetlands is increased by 50%. At the same time, the biomass of aerobic and anaerobic bacteria and fungi increased significantly. In addition, different microorganisms are responsible in removing different types of heavy metals and micropollutants.

Summary

This article provides useful information on the understanding of the diversity of microbes, influencing factors on the growth of microorganisms, and the efficiency of pollutant removal process in CWs. Overall, this review provides new ideas and directions for the improvement of constructed wetlands from a microbiological perspective.

In this review article, a comprehensive meta-analysis based on available literature information has been undertaken to make a relative comparison of total arsenic in rice grain. This involves analyzing the findings of various peer-reviewed studies that examined arsenic-contaminated Asian regions. Also, this article highlights the regional-level human health risks caused by the consumption of arsenic-contaminated rice in the three regions of Asia. Deriving such information at the continental level is of major importance in view of the need for proper monitoring and alleviating serious and continually emerging human health issues in arsenic-contaminated areas. One aim of this paper is to highlight the potential of a viable modeling approach for appraising the danger posed by arsenic in soil-plant-human system. There is an urgent need to fix the safe limit of bioavailable arsenic in soil because total arsenic in soil is not a good index of the arsenic hazard. Our hypothesis is finding out whether the modeling approach can be used in establishing a safe limit of bioavailable arsenic in soils with reference to human health. To achieve the above-mentioned objectives, we have selected reported rice grain arsenic content data from Asian countries following the PRISMA guidelines. Carcinogenic and non-carcinogenic risk was calculated following the US EPA’s guidelines. It emerged that adults in Asian countries are prone to a high risk of cancer due to their consumption of arsenic-contaminated rice. South Asia (SA), South East Asia (SEA), and East Asia (EA) exceeded the US EPA-prescribed safe limit for cancer risk with ~ 100 times higher probability of cancer due to rice consumption. The hazard quotient for the ingestion of arsenic containing rice was 4.526 ± 5.118 for SA, 2.599 ± 0.801 for SEA, and 2.954 ± 2.088 for EA. These figures are all above the permissible limit of HQ of 1. The solubility free ion activity model can predict arsenic transfer from soil to rice grain based on easily measurable soil properties and be used to fix the safe limit of bioavailable arsenic in paddy soils. The methods and findings of this review are expected to be useful for regional-level policymaking and mobilizing resources to alleviate public health issues caused by arsenic.

Purpose of Review

Chronic inorganic arsenic (iAs) exposure affects over 220 million people throughout the world. Given that iAs is ubiquitous in the environment, it is important to understand the human health consequences of chronic iAs exposure. The purpose of this review is to highlight and evaluate research findings within the past 5 years that address the molecular mechanisms responsible for cancers caused by chronic iAs exposure. We also propose new research directions for the iAs research field based on the newest uncovered mechanisms for how this age-old poison promotes cancer.

Recent Findings

Within the past 5 years, studies provide evidence that chronic iAs exposure promotes kidney, prostate, liver, and breast cancer in humans. New molecular mechanisms that promote cancer development by iAs exposure in skin, lung, bladder, kidney, prostate, liver, and breast include histone modifications, DNA and RNA methylation, non-coding RNA expression, disruption of alternative splicing, and inhibition of the DNA damage response.

Summary

Recent studies highlight disruption of epigenetic and epitranscriptomic modifications and/or the DNA damage response by chronic iAs exposure across many models of iAs-induced carcinogenesis, including cancers that are not classically defined as being caused by chronic iAs exposure. Understanding the molecular mechanisms underlying initiation and metastasis of iAs-induced cancers is essential for improving detection and targeted treatment of iAs-induced cancers.

Graphical Abstract

Purpose of Review

Microplastics in the environment enter the human body through diet, drinking water, and air inhalation. The widespread detection of microplastics in several human tissues was conducted. However, limited knowledge exists on the number of microplastics that can be ingested by humans and the potential adverse effects on various organs. To address these issues, we reviewed the types and abundance of microplastics through different pathways and summarized the average annual intake in humans.

Recent Findings

An adult can ingest about (4.88–5.77) × 10⁵ microplastics/year through the dietary route [including salt (5.00–7.00) × 10³, fish (0.50–1.20)×10⁴, fruits (4.48–4.62) × 10⁵, and vegetables (2.96–9.55)×10⁴]. The amount of microplastics ingested via drinking water route was approximately (0.22–1.2)×10⁶ microplastics/year. Inhalation of microplastics via atmospheric environment was nearly (0.21–2.51) × 10⁶ microplastics/year [including indoor (0.16–2.30) × 10⁶ and outdoor (0.46–2.10)×10⁵].

Summary

In conclusion, we found that the human body ingests microplastics most through inhalation, followed by drinking water and diet. We also summarized the types and abundance of microplastics that were enriched in different organs after microplastics entered the human body. Microplastics entering the body would cross the barrier into the target effector organs and cause adverse health effects, mainly including induction of intracellular oxidative stress, genotoxicity, reproductive toxicity, and inflammatory responses. In conclusion, exposure to microplastics can cause many adverse effects on the health of the organism. Thus, an increased awareness of the crisis, urgent discussion, and practical actions are needed to mitigate microplastics contaminants in the environment.

Graphical Abstract

Purpose of Review

The issue of improper wastewater treatment disposal from various sources is a global issue that needs immediate tackling. The increase in global population, sustainable agricultural practice, and heightened energy production demand has increased the need for clean water supply to multiple fold. It is therefore a continuous challenge to develop technique that could treat the wastewater as efficient but at a lower production cost with sustainable supply of raw materials.

Recent Findings

Apart from the extensively studied forest and forest industry residues, date palm (Phoenix dactylifera L.) offers an exciting future as a sustainable raw material to produce biochar and/or activated carbon that can be employed as a green adsorbent in wastewater treatment application. Various carbonization and activation techniques have been reported for date palm waste biomass as well as its potential applications. Nevertheless, there are very few literatures available on the benchmarking of each date palm biomass type for its characteristics, production methods, and pollutant removal capabilities.

Summary

This review highlights some of the carbonization and activation methods available to manufacture biochar and activated carbon from date palm followed by some examples of its applications. Even though date palm biomass can be found in huge volume in date palm-growing area such as the Arab region, few reports are available on its utilization in actual industrial processes, pollutant removal from water system, for example. This review offers new insight into the conversion techniques of date palm biomass, its characterization, and evaluation of its pollutant removal capacity, among others. This work is envisaged to shed insight into a comprehensive outlook on the promising applications of date palm biomass to produce potent green adsorbents as well as its potential applications in other economic sectors.

Purpose of Review

Pollution from wastewater is a perpetual environmental issue worldwide that negatively impacts the ecosystem and human beings. The use of natural-based compounds such as cyclodextrin (CD) to remove pollutants from water and wastewater systems has been reported by various researchers. Nevertheless, its direct use in wastewater treatment is hampered by its water-soluble properties. Beta-cyclodextrin (β-CD) is a cyclic oligosaccharide compound that can effectively trap pollutants from wastewater by the formation of truncated inclusion complex with various molecules. Hence, it is the motivation of this article to review the effectiveness and the recent strategies of crosslinked-β-CD toward remediation of various pollutants from wastewater.

Recent Findings

The crosslinked-β-CD was found as an improvement for native β-CD in the purpose of wastewater pollutant remediation. Strategies in chemical crosslinking include the choice of suitable crosslinkers, the type of support materials, and surface modifications. It was observed that different strategies resulted in various degrees of performance of the composite β-CD adsorbents. The efficiency of adsorption process was influenced by the operational parameters such as pH, contact time, and initial pollutant concentration, whereby it was characterized by the recyclability, adsorption capacity, and mechanical strength. The emergence of nanotechnology has led to a great improvement to the existing composite-β-CD adsorbent by providing a large surface area, where it can be easily functionalized and modified toward the targeted molecules.

Summary

Crosslinking is a versatile method for developing a composite-β-CD adsorbent for pollutant uptake as it employs a simple technique and performs a simple separation process with moderate operational conditions.

Graphical Abstract

The 3D structure of β-cyclodextrin resembles a truncated cone, having characteristics of hydrophilic surface and hydrophobic cavity and capable to trap molecules inside its cavity. The graphical abstract shows the flows of this review paper. The crosslinking strategies, the operational parameters, and the adsorption performance of the composite CD-adsorbents were reviewed and discussed

Purpose of Review

The unique properties of per- and polyfluoroalkyl substances (PFASs) have seen their widespread adoption, subsequent accumulation in the environment and concern regarding potential environmental effects. Globally, airfields and paved firefighting training surfaces are hotspots for accumulation of PFAS due to extensive use of aqueous film-forming foams (AFFF). Evidence from contaminated concrete and asphalt airfield and training pavements suggests they may serve as an enduring PFAS source. This review investigates sealants as remediation technologies to minimise PFAS mobilisation from pavements drawing on current knowledge of remediation options for soils, sediments, surface and groundwaters.

Recent Findings

The review did not identify any published sealant information specific to PFAS. Our analysis showed that surface and penetrative sealants may offer an immediate solution via encapsulation of PFAS residues in concrete and asphalt. The most promising surface sealants likely to minimise water ingress and PFAS leaching are selected polymers and (modified) bitumen, owing to the relatively low cost, good adhesion, trafficability and chemical, heat and UV resistance. Potential also exists to enhance PFAS immobilisation using additives to absorb or otherwise chemically bind PFAS. Prospective penetrative sealants include silicates or siloxanes that bind to internal mineral surfaces and/or fill pores to restrict PFAS mobility. It is likely that combinations of surface and penetrative sealants will be required to meet functional, operational and management requirements with respect to new or existing contamination in concrete or asphalt pavements.

Summary

At present, few if any sealants have been evaluated for their ability to bind or mitigate PFAS mobility. This review serves as a starting point for further studies to evaluate their short or long-term effectiveness in immobilisation of PFAS residues in in situ or ex situ concrete and asphalt. Several knowledge gaps along with suggestions for future research have been made.

Exposure to heavy metals in indoor dust may affect human health and has gained increasing attention in recent years. However, the occurrence, sources, and health risks of heavy metals in indoor dust in China are still poorly understood, thus leading to certain knowledge gaps. This review systematically discussed the pollution characteristics and the associated health risks of heavy metals in indoor dust in China. Results show that the heavy metals in indoor dust in China are more serious than that in other countries with concentration distribution patterns of Zn > Mn > Pb > Cu > As > Cr > Ni > V > Co ≈ Cd > Hg. Mining and smelting activities, electronic waste recovery, and industrial production can increase heavy metal concentrations in indoor dust in sampling cities. Due to the variation of sources, significant spatial differences are observed among different regions and between rural and urban homes. Results from source apportionment show that mining activity and traffic are the dominant sources of indoor heavy metals. In comparison with adults, children have higher non-carcinogenic and carcinogenic risks due to more frequent ingestion of indoor heavy metals. Residents in South China are suffering from high carcinogenic risks due to high As occurrence levels. Children in South, East, and Southwest China are suffering from non-carcinogenic risks due to Pb exposure. To our theme, more studies, especially in rural homes, involved with more kinds of microenvironments are welcomed in the future. Meanwhile, in the premise of setting a standard guideline for a consistent target heavy metal, activity patterns should be considered when estimating the health risk. Results from this study are expected to provide crucial information for policymakers and researchers to alleviate indoor heavy metal pollution.

Graphical Abstract

Purpose of Review

There is a growing interest in understanding the health effects of exposure to per- and polyfluoroalkyl substances (PFAS) through the study of the human metabolome. In this systematic review, we aimed to identify consistent findings between PFAS and metabolomic signatures. We conducted a search matching specific keywords that was independently reviewed by two authors on two databases (EMBASE and PubMed) from their inception through July 19, 2022 following PRISMA guidelines.

Recent Findings

We identified a total of 28 eligible observational studies that evaluated the associations between 31 different PFAS exposures and metabolomics in humans. The most common exposure evaluated was legacy long-chain PFAS. Population sample sizes ranged from 40 to 1,105 participants at different stages across the lifespan. A total of 19 studies used a non-targeted metabolomics approach, 7 used targeted approaches, and 2 included both. The majority of studies were cross-sectional (n = 25), including four with prospective analyses of PFAS measured prior to metabolomics.

Summary

Most frequently reported associations across studies were observed between PFAS and amino acids, fatty acids, glycerophospholipids, glycerolipids, phosphosphingolipids, bile acids, ceramides, purines, and acylcarnitines. Corresponding metabolic pathways were also altered, including lipid, amino acid, carbohydrate, nucleotide, energy metabolism, glycan biosynthesis and metabolism, and metabolism of cofactors and vitamins. We found consistent evidence across studies indicating PFAS-induced alterations in lipid and amino acid metabolites, which may be involved in energy and cell membrane disruption.

Purpose of Review

Triclosan (TCS), a widely used broad-spectrum antimicrobial agent, enters to wastewater treatment plants (WWTPs) and the environment ultimately after its usage. Notably, the use of TCS has surged during the outbreak of COVID-19, leading to the environment under increasing TCS pollution pressure. Even environmentally relevant concentrations of TCS can promote the development of antimicrobial resistance (AMR), which is a major public health concern. The purpose of this study is to provide a basis for the management and risk assessment of TCS by providing a holistic review of the impact of TCS on AMR in the environment.

Recent Findings

Bacterial resistance to TCS mainly takes place through modification or replacement of the FabI enzyme, which is the main target of TCS in bacteria. Currently, multiple FabI mutants and isoenzymes have been identified in the environment giving bacterial resistance to TCS. In addition, mechanisms by which TCS promotes bacterial development of resistance to other antimicrobials have been studied in laboratory experiments and environmental settings, such as anaerobic digester. TCS will promote the development of AMR in the environment with the possibility of adverse risks to public health.

Summary

This review systematically summarizes the mechanisms of bacterial resistance to antimicrobials driven by TCS and highlights the effects of TCS in promoting the horizontal transfer and enrichment of antibiotic resistance genes (ARGs). Suggestions for overcoming the limitations of laboratory-scale studies and further improving the risk assessment of TCS in the environment are proposed.