Zhou Qixing

Countermeasures of Reclaimed Municipal Wastewater for Safety of Agricultural Use in China

Abstract China is facing a severe water resource crisis, and the shortage of water for agricultural consumption is a prominent problem. Irrigation with reclaimed municipal wastewater that can reach the agricultural recycling standards is an important way to deal with water shortage in agricultural production. Owing to the complex sources of municipal wastewater, there are multifarious pollutants in municipal wastewater. Improper use of wastewater can cause potential risks to ago- environment, agricultural products safety, and human health. This article deals with the current situation and the development prospects of reclaimed wastewater for agricultural use in China and abroad; the potential risks to human health and environmental pollution from the reclaimed municipal wastewater for agricultural reuse are also discussed. And some countermeasures and advices of reclaimed municipal wastewater for safety of agricultural reuse are provided.

Review on attenuation of nanotoxicity andthe mechanisms

Nanoparticles (NPs) with excellent properties have been rapidly developed and applied in various fields such as phototherapy, early cancer diagnosis, drug carriers, electronic components, cosmetics, food additives, water treatment, and soil remediation. Humans could be directly exposed to these NPs via these applications. These NPs or NP-containing products could also be released into the environment, leading to potential environmental risks. Therefore, the environmental and health risks of nanomaterials urgently need to be assessed, especially for the development of control methodologies. Methods for control or regulation of nanomaterial risks are still in the developmental stages, and some knowledge gaps and ambiguities still exist. To address these knowledge gaps and to guarantee the sustainable development of nanote- chnology, this review discusses the attenuation of nanotoxicity and mechanisms thereof. Physicochemical properties of NPs, such as size, purity, and surface properties (surface charge, hydrophilicity, and surface modification) influence their interactions with biological systems. Environmental conditions during the interaction of NPs with cells, such as exposure dose and time and reaction media, also affect nanotoxicity. Optimization of these physicochemical properties and environmental conditions is expected to aid the design of ideal NPs and control adverse effects of NPs. Nanotoxicity has been reported to be reduced by adjusting size, purity, surface properties (surface charge, hydrophilicity, and surface modification), exposure dose and time, and reaction media of NPs. Herein, the corresponding progress and challenges are also discussed individually. Moreover, this review elaborates on toxic mechanisms and attenuation of nanotoxicity involving five aspects: chemophysiological damage of cellular and subcellular structures, oxidative stress, genes, proteins, and metabolism. Understanding mechanisms underlying the interaction of NPs with biological systems would be conducive to the prediction of nanotoxicity and the design of experiments to attenuate this nanotoxicity. Currently, further studies need be conducted to explore NP uptake, absorption, distribution, interaction, and elimination in biological systems or cells. Globally, the methods of nanotoxicity attenuation remain immature, and well-corroborated methods are unavailable. Finally, perspectives on future research in nanotoxicity attenuation are proposed. An understanding of nanotoxicology and the development of related control methods affect multiple disciplines, including medicine, chemistry, physics, biology, and environmental science. Therefore, multidisciplinary experts need to urgently work together to ensure the sustainable development of nanotechnology.

The research progress in migration, distribution, biological effects and analytical methods of microplastics

Microplastics (MPs) are synthetic organic polymers. The particle sizes of MPs range from approximately 0.01 to 5 nm. The photodegradation of MPs is more difficult than that of bulk plastics. Therefore, MPs are regarded as potential persistent organic pollutants. Researches of MPs have become a hot spot, and lots of MPs studies were reported recently. Although there are a lot of studies on the migration, distribution, biological effects and analytical methods of MPs in natural environments, systematic and comprehensive review articles are emergent, especially for the recent literatures. The present work summarized the researches involving the migration, distribution, biological effects and analytical methods of MPs in recent years. MPs are generally divided into two types, primary MPs and secondary MPs. Primary MPs are intentionally designed and produced for certain purposes, while secondary MPs generate from the fragmentations of bulk plastics and the breakage of clothes fibers. Currently, researches of MPs distribution focus on in marine environments, and found that MPs distributed throughout the ocean, even in the north and south poles, driven by the flow of sea water. However, researches of on MPs distribution in fresh water and terrene are limited. Researches also showed that MPs could migrate among terrestrial, freshwater and marine environments, where freshwater environments affected the migration and interaction of MPs between terrene and marine environments. Studies of biological effects of MPs focus on two parts, ingestion effects and combined effects with organic contaminants. Ingestion of MPs damages living beings and then MPs transfer through food chains. The responses of living beings to MPs are mainly related to sublethal effects at environmental-relevant concentrations. The inhibition of individual growth and reproduction, disturbance of proteins and genes, and reduction of nutrition uptake were reported for specific physiological effects of MPs. Some researches proposed that MPs could be accumulated in living organisms. Therefore, humans, as a part of the food chains, will inevitably be affected by MPs. The organic contaminants combine with the MPs released from the plasticizers in the production of MPs and then are adsorbed in the natural environments. MPs have been found in seafood. As a result, MPs become one medium of human exposure to organic pollutants. The analysis and identification of MPs are critical to other researches, such as environmental behaviors and toxicity. In general, the analytical methods of plastic include physical and chemical characterizations. Physical characterizations involve visual, microscopy and spectroscopy methods. Chemical characterization methods, such as differential scanning calorimetry (DSC), gas chromatography mass spectrometry (GC-MS), scanning electron microscope and energy disperse spectroscopy (SEM-EDS), and thermal desorption gas chromatography mass spectrometry (TDS-GC-MS) are frequently used in chemical characterizations. Although lots of analytical methods were proposed by researchers, there are still some shortcomings and limitations, for example, the influence from environmental or biological matrices. It is necessary to develop effective and accurate methods for the analysis of MPs. Through many researches of MPs were reported recently, the information of source, migration, distribution, biological effects and analytical methods of MPs is not enough to scientifically evaluate their environmental and health risks. Consequently, the present review also proposes some perspectives for MPs researches. It is worth to study the distribution of MPs in terrestrial and freshwater environments, the biological effects at individual level, the prevention and control of MPs pollution and the environmental behavior of nanoplastics. Integrating the data of MPs source, distribution, behavior and toxicity is necessary to the scientific evaluations of MPs risks. This review provides insights in the control techniques and theoretical researches of MPs.