Environmental Chemistry Letters最新文献

The negative effects of the accelerating climate change due partly to fossil fuel consumption is calling for the rapid development of sustainable energies such as biohydrogen, which is produced using microorganisms. Here we review biohydrogen production from biomass, with focus on biomass pretreatment, fermentative production, factors affecting production, bioreactors, kinetics and modeling, and improved production with nanoparticles. Pretreatments include chemical, physical and biological methods. Hydrogen production is done by photo-fermentation or dark fermentation. Influencing factors comprise pH, temperature, hydraulic retention time, and the presence of fermentation inhibitors. Continuous stirred tank-, anaerobic fluidized bed-, anaerobic sequencing batch-, up-flow anaerobic sludge blanket- and dynamic membrane reactors are used. Additives include cobalt, nickel and iron nanoparticles. Compared to thermochemical, photochemical and electrochemical processes, biohydrogen production needs more time but is easy to operate, cost-effective and environmentally friendly.

Microplastics have been recently detected in many environmental media and living organisms, yet their transfer and toxicity to humans are poorly known. Here, we review microplastic transfer in the food chain with focus on microplastic pollution sources, methods to analyze microplastics in food, health impact of food-related microplastic exposure, and remediation of microplastic pollution. Microplastic pollution sources include seafood, food additives, packaging materials, and agricultural and industrial products. Remediation techniques comprise the use of microbial enzymes and biofilms. Microplastic detection methods in food rely on separation and quantification by optical detection, scanning electron micrography, and Fourier-transform infrared spectroscopy. Human health impact following microplastic ingestion include cancers, organ and respiration damage, and reproductive impairments. Overall, microplastic toxicity is mainly due to their ability to enter the metabolism, adsorption into the circulatory system for translocation, and difficulty, if not impossibility, of excretion.

Despite the major influence of soils on climate change, carbon sequestration, pollution remediation, and food security, soil remains a largely unexplored media with an extreme complexity of microbes, minerals, and dead organic matter, most of them being actually poorly known. In particular, soil biofilms have recently attracted attention because they strongly influence biogeochemical reactions and processes. Here we review biofilms with focus on their behavior, proliferation, distribution, characterization methods, and applications. Characterization methods include optical, electron, scanning probe, and X-ray microscopy; metagenomics, metatranscriptomics, metaproteomics, metabolomics; and tracking approaches. Applications comprise pollution remediation by metal immobilization or organics degradation; and methane oxidation, carbon dioxide reduction, and carbon sequestration. Advanced methods such as DNA-stable isotope probing and meta-omics have uncovered the multiple functions of soil biofilms and their underlying molecular mechanisms. Investigations have improved our understanding of inter- and intra-kingdom interactions, and of gene transfer. Extracellular materials such as polysaccharides enhance the transport of substances and electrons flow among microorganisms.

Infrastructure deterioration is a threat to developed countries, emphasizing the need for effective management techniques. In particular, the leakage of aged domestic sewer pipeline is a major health issue, yet there is a lack of markers to identify domestic leakage. We studied the pollution in urban waters resulting from domestic sewage leakage into storm drainages. We monitored caffeine, fragrance substances and polycyclic aromatic hydrocarbons (PAHs) in the storm discharge points in five urban districts having separate sewer systems aged from 10 to over 40 years. Results show that caffeine and fragrance concentrations tended to increase with sewer system age. For instance, caffeine concentrations in the areas of sewer systems over 40 years old were at least two orders of magnitude higher than in 10-year-old sewer systems, and were as high as 1–10% of domestic sewage, strongly suggesting the leakage of domestic sewer pipelines. PAHs exhibited consistent patterns across the districts. Overall, we observe that sewer leaking processes can be distinguished by analyzing the levels of organic pollutants.

The rapid growth of textile industry and fast-fashion has led to the production of about 92 million ton of textile waste per year. Nearly 85% of textile waste is disposed of by landfill and incineration, causing serious environmental pollution and huge resource waste, calling for alternative textile production. Here we review the green production of textiles with focus on additive manufacturing, 3- and 4-dimension printing, recycling textile waste, and synthetic and natural fibers. Additive manufacturing technologies, particularly 4-dimension printing, is flexible, green, and allows on-demand manufacturing, which is one solution to the textile waste problem. 4-Dimension printing contributes to the development of intelligent materials, and can create structures that deform in response to external stimuli. Textile waste contains high-quality, low-cost materials that can be re-used and recycled. Applications include smart textiles, flexible electronics, soft robotics, human–computer interaction, and wearable devices.

Microplastics are emerging contaminants that undergo progressive aging under environmental conditions such as sunlight irradiation, mechanical forces, temperature variations, and the presence of biological organisms. Since aging modifies microplastic properties, such as their own toxicity and the toxicity of trapped pollutants, advanced methods to analyze microplastics are required. Here we review methods to analyze microplastic aging with focus on the aging process, qualitative identification, quantitative characterization, and chemometrics. Qualitative identification is done by mechanical techniques, thermal techniques, e.g., thermal degradation and gas chromatography–mass spectrometry, and spectral techniques, e.g., infrared, Raman, fluorescent, and laser techniques. Quantitative characterization is done by microscopy and mass spectrometry. Microplastic aging results in a series of surface physical changes, biofilm formation, chemical oxidation, thermal alternation, and mechanical deterioration. Changes in mechanical and thermal properties allow to differentiate aged microplastics. Infrared and Raman spectroscopy are rapid and sensitive for chemical identification of microplastics in complex environmental samples. Combining two techniques is preferable for accurate detection and categorization.

Bioplastics appear as an alternative to fossil fuel-derived plastics because bioplastics are carbon neutral and often biodegradable, thus potentially solving the issues of plastic pollution and climate change. In particular, polylactic acid is a substitute for traditional petrochemical-based polymers. Here, we review polylactic acid production with focus on surface modification and integration of bioactive compounds. Surface can be modified by chemical treatment, photografting, surface entrapment, plasma treatment, and coating. Bioactive compounds can be incorporated by encapsulation, impregnation, melt blending, solvent casting, electrospinning, and in situ polymerization. Biomedical and packaging applications are discussed.

Microplastics are micrometre-sized emerging pollutants produced by plastic fragmentation. They have been recently detected in most ecosystems, even in remote areas. Here, we review microplastics with emphasis on sources, occurrence, transport, detection methods, policies, toxicity, and management methods. In the transport section, we discuss sorption kinetics, layered microplastics, and influencing factors such as biofilm formation. Microplastic management can be done by adsorption, filtration, oxidation, and biodegradation. Microplastic interaction is influenced by temperature, pH, salinity, and dissolved organic matter.

Microplastics are emerging contaminants that have been detected recently in most environmental and biological systems, yet their health risk for humans has not been clearly summarized. Here we review human health risk associated with exposure to microplastics with focus on methods of exposure assessment, hazard identification, dose–response assessment, exposure assessment, and risk characterization. Hazards include direct hazards, hazards from contaminants released by microplastics, and hazards from microplastic interactions with surrounding contaminants. Microplastics trigger oxidative stress, disrupt metabolism, interfere with gut microflora and gastrointestinal functions, disrupt hepatic, cardiopulmonary and immune systems, and degrade reproductive health. Some additives leached from microplastics such as phthalates are endocrine disruptors and thus impact reproductive health. The interaction of microplastics with other pollutants in the environment induces varied hazards following synergistic or antagonistic effects.

Pollution by polycyclic aromatic hydrocarbons, lead, mercury, arsenic, cadmium, and chromium is impairing marine ecosystems. Here, we review the effect of these contaminants on coral reefs and mangrove ecosystems, with focus on reef fishes, algae, corals, and oil spills. We also discuss the effects of natural hydrocarbons. Some polycyclic aromatic hydrocarbons display carcinogenic and mutagenic properties. Heavy metals are highly toxic to most marine living organisms, causing reproductive failure, deoxyribonucleic acid damage, and neurological problems. Heavy metals accumulate through the food chain, ending up in humans who eat seafood. Mangroves and coral reefs can be severely impacted with diminished water quality, reduced biodiversity, compromised fish habitats, decreased fish catches, and damaged seagrass beds, ultimately affecting other coastal habitats.