Source,migration,distribution,toxicological effects and remediation technologies of arsenic in groundwater in China

Groundwater with high arsenic(As) content seriously threatens human life and health. Drinking high-As groundwater for a long time will lead to various pathological changes such as skin cancer, liver cancer,and kidney cancer. High-As groundwater has become one of the most serious environmental geological problems in China and even internationally. This paper aims to systematically summarize the sources,migration, distribution, toxicological effects, and treatment techniques of As in natural groundwater in China based on a large number of literature surveys. High-As groundwater in China is mainly distributed in the inland basins in arid and semi-arid environments and the alluvial and lacustrine aquifers in river deltas in humid environments, which are in neutral to weakly alkaline and strongly reducing environments.The content of As in groundwater varies widely, and As(Ⅲ) is the main form. The main mechanism of the formation of high-As groundwater in China is the reduced dissolution of Fe and Mn oxides under the action of organic matter and primary microorganisms, alkaline environment, intense evaporation and concentration, long-term water-rock interaction, and slow groundwater velocity, which promote the continuous migration and enrichment of As in groundwater. There are obvious differences in the toxicity of different forms of As. The toxic of As(Ⅲ) is far more than As(V), which is considered to be more toxic than methyl arsenate(MMA) and dimethyl arsenate(DMA). Inorganic As entering the body is metabolized through a combination of methylation(detoxification) and reduction(activation) and catalyzed by a series of methyltransferases and reductases. At present, remediation methods for high-As groundwater mainly include ion exchange technology, membrane filtration technology, biological treatment technology, nanocomposite adsorption technology, electrochemical technology, and so on. All the above remediation methods still have certain limitations, and it is urgent to develop treatment materials and technical means with stronger As removal performance and sustainability. With the joint efforts of scientists and governments of various countries in the future, this worldwide problem of drinking-water As poisoning will be solved as soon as possible. This paper systematically summarizes and discusses the hot research results of natural high-As groundwater, which could provide a reference for the related research of high-As groundwater in China and even the world.

Toxicological Effects of Secondary Air Pollutants

Secondary air pollutants,originating from gaseous pollutants and primary particulate matter emitted by natural sources and human activities,undergo complex atmospheric chemical reactions and multiphase processes.Secondary gaseous pollutants represented by ozone and secondary particulate matter,including sulfates,nitrates,ammonium salts,and secondary organic aerosols,are formed in the atmosphere,affecting air quality and human health.This paper summarizes the formation pathways and mechanisms of important atmospheric secondary pollutants.Meanwhile,different secondary pollutants’toxicological effects and corresponding health risks are evaluated.Studies have shown that secondary pollutants are generally more toxic than primary ones.However,due to their diverse source and complex generation mechanism,the study of the toxicological effects of secondary pollutants is still in its early stages.Therefore,this paper first introduces the formation mechanism of secondary gaseous pollutants and focuses mainly on ozone’s toxicological effects.In terms of particulate matter,secondary inorganic and organic particulate matters are summarized separately,then the contribution and toxicological effects of secondary components formed from primary carbonaceous aerosols are discussed.Finally,secondary pollutants generated in the indoor environment are briefly introduced.Overall,a comprehensive review of secondary air pollutants may shed light on the future toxicological and health effects research of secondary air pollutants.

Toxicological effects of rare earth yttrium on wheat seedlings(Triticum aestivum)

This study examined the biochemical responses of wheat（Triticum aestivum） to the stress of rare earth yttrium（Y） and showed that 25–100 mg/kg Y treatments evidently increased the biomass（root mass,shoot mass and leaf mass）,accompanied by a significant（p0.05） increase in the chlorophyll（CHL） content in wheat leaves.Increased malondialdehyde（MDA） levels were detected in wheat shoots（stem and leaf） and roots too,indicating the presence of poisoning active oxygen species（AOS）.The MDA content in wheat roots increased with the augmentation of Y concentration.These results indicated that there was a dose-dependent effect of Y on the changes of MDA content in wheat roots.Although the activities of superoxide dismutases（SOD）,peroxidases（POD） and catalases（CAT） in wheat shoots and roots irregularly fluctuated with the increase in Y concentration,25–100 mg/kg Y significantly（p0.01） increased the activities of SOD and POD.In general,the dose-dependent effects of Y on the activity of antioxidant enzymes were insignificant.Our data also indicated that the increase in SOD and POD activities could be used as a good biomarker for the stress induced by low concentrations of Y.

Potential Toxicological and Cardiopulmonary Effects of PM2,5 Exposure and Related Mortality:Findings of Recent Studies Published during 2003-2013

Air pollution has environmental issue owing become a serious to its diverse harmful effects on the physical and biological environment. According to the Environmental Protection Agency （EPA） and the World Health Organization （WHO）, air pollution affects millions of people worldwide. Hundreds of thousands of deaths each year and a range of diseases, particularly among vulnerable groups （i.e., children, the elderly, and people with special medical conditions）, are attributed to air pollution. These effects are not always caused by single pollutant in the air; rather, they are considered consequences of the multi-pollutants to which people are simultaneously exposed.

Research progress and quality markers prediction analysis of Dysosma versipellis

Dysosma versipellis is the rhizome of Bajiaolian in Berberaceae.It is a unique medicinal plant in China and it was the first to be recorded in Shennong’s Classic of Materia Medica(unknown author,25–220 C.E.).It has complex chemical components as well as complex,pharmacological and toxicological effects are extensive.Based on the recent research progress,the chemical constituents,pharmacological activities and toxicological effects of Dysosma versipellis were summarized.Combined with the core concept of quality markers of traditional Chinese medicine,the prediction and analysis were carried out from the aspects of phytogenetics and the source pathway of specific chemical constituents,traditional medicinal properties,traditional efficacy,chemical composition measurability,blood components,and pharmacokinetics,in order to provide reference for further study of Dysosma versipellis.

Phytotoxicity of cadmium on protein, proline and antioxidant enzyme activities in growing Arachis hypogaea L. seedlings

Phytotoxicity of cadmium on growing Arachis hypogaea L. seedlings was studied. Seeds were exposed to 25, 50, and 100 μmol/L CdCl2 concentrations, for a period of 10, 15, 20 and 25 d. The extent of damage to chlorophyll, protein, proline, nitrate and nitrite reductase, antioxidant enzyme activity in leaves and roots were evaluated after 10 d of cadmium stress. The higher concentration of cadmium （100 μmol/L） resulted （leaves and roots） total chlorophyll 91.01%, protein 79.51%, 83.61%, nitrate reductase 79.39%, 80.72% and nitrite reductase 77.07%, 75.88% activity decreased with increase in cadmium concentrations and exposure periods. Cadmium caused significant changes in the activity of antioxidative enzymes. Contrastingly Cd treated plant tissues showed an increase in proline 159.87%, 239.6%, gluthion reductase （GR） 337.72%, 306.14%, superoxide disumutase （SOD） 688.56%, 381.72%, ascorbate peroxidase （APX） 226.47%, 252.14%, peroxidase （POD） 72.19%, 60.29% and catalase （CAT） 228.96%, 214.74% as compared to control. Cadmium stress caused a significant increase in the rate of SOD activity in leaves and roots of plant species. Results show the crop A. hypogaea is highly sensitive even at very low cadmium concentrations.

Birds and plastic pollution:recent advances

Plastic waste and debris have caused substantial environmental pollution globally in the past decades,and they have been accumulated in hundreds of terrestrial and aquatic avian species.Birds are susceptible and vulnerable to external environments;therefore,they could be used to estimate the negative effects of environmental pollution.In this review,we summarize the effects of macroplastics,microplastics,and plastic-derived additives and plastic-absorbed chemicals on birds.First,macroplastics and microplastics accumulate in different tissues of various aquatic and terrestrial birds,suggesting that birds could suffer from the macroplastics and microplastics-associated contaminants in the aquatic and terrestrial environments.Second,the detrimental effects of macroplastics and microplastics,and their derived additives and absorbed chemicals on the individual survival,growth and development,reproductive output,and physiology,are summarized in different birds,as well as the known toxicological mechanisms of plastics in laboratory model mammals.Finally,we identify that human commensal birds,long-life-span birds,and model bird species could be utilized to different research objectives to evaluate plastic pollution burden and toxicological effects of chronic plastic exposure.

Evaluation of the biological toxicity of fluorine in Antarctic krill

Antarctic krill is a potentially nutritious food source for humans, but lfuorine （F） toxicity is a matter of concern. To evaluate the toxicity of F in Antarctic krill, 30 Wistar rats were divided into three groups with different dietary regimens：a control group, a krill treatment group （150 mg＆#183;kg-1 F）, and a sodium lfuoride （NaF） treatment group （150 mg＆#183;kg-1 F）. After three months, F concentrations in feces, plasma, and bone were determined, and the degree of dental and skeletal lfuorosis was assessed. The F concentrations in plasma and bone from the krill treatment group were 0.167 0＆#177;0.020 4 mg.L-1 and 2 709.8＆#177;301.9 mg＆#183;kg-1, respectively, compared with 0.043 8＆#177;0.005 5 mg＆#183;L-1 and 442.4＆#177;60.7 mg＆#183;kg-1, respectively, in samples from the control group. Concentrations of F in plasma and bone in the krill treatment group were higher than in the control group, but lower than in the NaF treatment group. The degree of dental lfuorosis in the krill treatment group was moderate, compared with severe in the NaF treatment group and normal in the control group. The degree of skeletal lfuorosis did not change signiifcantly in any group. These results showed that the toxicity of F in Antarctic krill was lower than for an equivalent concentration of F in NaF, but it was toxic for rats consuming krill in large quantities. To conclude, we discuss possible reasons for the reduced toxicity of F in Antarctic krill. The present study provides a direct toxicological reference for the consideration of Antarctic krill for human consumption.