Response of growth, antioxidant enzymes and root exudates production towards As stress in Pteris vittata and in Astragalus sinicus colonized by arbuscular mycorrhizal fungi Abstract The modern agricultural practices have led to improve the contaminated soils with a variety of heavy metals that have become a major environmental concern. The use of arbuscular mycorrihizal fungi (AMF) is considered a potential tool for the sustainable agriculture especially in contaminated sites. Moreover, recently, the use of AMF has become a fascinating and multidisciplinary subject for the scientists dealing with plant protection. The present study was carried out to evaluate the interaction among arsenic (As) species, AMF, and two plant species: Pteris vittata and Astragalus sinicus, differing in their metal tolerance. Results about A. sinicus revealed that the biomass was affected as As (III and V) accumulated in the roots of A. sinicus, and in rachis and pinnae of P. vittata. The inoculation of AMF markedly increased the biomass yield of the both plants when exposed to As species. The exposure to the As species resulted variation and non-significant results about antioxidant enzymes and non-enzymes when grown in As stress with and without AMF. The inoculation of AMF under As species improved the organic acids concentrations in both plant species. Overall, the concentration of oxalate acid was more than formic and malic acids; however, AMF inoculation improved more organic acids in A. sinicus. P. vittata exhibited more activities of antioxidant enzymes and non-enzymes under As stress with and without AMF than A. sinicus, and hence had a more efficient defense mechanism.

Quantitatively ranking the influencing factors of ammonia volatilization from paddy soils by grey relational entropy Abstract Ammonia (NH3) volatilization from paddy soils is a main source of atmospheric NH3 and the magnitude is affected by many factors. Because of the complex field condition, it is difficult to identify the relative importance of individual factor on NH3 volatilization process in different locations and at different times. In this study, the grey relational entropy method was used to evaluate the relative impact of four main factors (i.e., nitrogen fertilizer application rate, NH4-N concentration, pH, and temperature of the floodwater) on NH3 volatilization loss from three different field experiments. The results demonstrated that floodwater NH4-N concentration was the most important factor governing NH3 volatilization process. Floodwater pH was the second most important factor, followed by temperature of the floodwater and nitrogen fertilizer application rate. We further validated the grey relational entropy method with NH3 volatilization loss data from other published study and confirmed the order of importance for the four factors. We hope the findings of this study will be helpful for guiding design to reduce paddy soil NH3 emission.

Selected food processing techniques as a factor for pesticide residue removal in apple fruit Abstract In this study, various food processing techniques, including high-temperature processes (pasteurization/sterilization and boiling), low-temperature processes (freezing), mechanical processing (peeling and juicing), and water-based processes (washing with tap water and ultrasonic washing) were used to identify the most effective way to remove contamination of 5 fungicides (cyprodinil, difenoconazole, fluopyram, tebuconazole, and fludioxonil). The most effective processes were juicing and freezing in the range between 63 and 100% and from 52 to almost 100%, respectively. Ultrasonic washing and boiling also significantly removed pesticide residues ranging from 79 to 84% and from 72 to 78%, respectively. The same trend was observed by peeling process where maximum reduction of 80% was achieved almost for all fungicides. Washing with tap water decreased the concentration levels in the range of 35–38%. This study demonstrated that the least effective and unpredictable method of decontamination of pesticides was sterilization and pasteurization, due to the large variation in pesticide levels during the process.

Selenium and mercury in dolphinfish ( Coryphaena hippurus ) from the Gulf of California: inter-annual variations and selenium health benefit value Abstract With the aim of determining the benefit from consumption of dolphinfish Coryphaena hippurus from La Paz and Cabo San Lucas in the southern area of the Gulf of California, mercury (Hg) and selenium (Se) were measured in liver and muscle of specimens (n = 362) collected between 2006 and 2013. Mean levels of Hg in muscle (0.61 μg g−1) and liver (0.42 μg g−1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas; in the case of Se, mean concentrations in liver (1.54 μg g−1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas. Hg levels in muscle were positively and significantly (p < 0.05) correlated with fork length and weight of fish; in liver, Hg and Se were significantly (p < 0.05) correlated with fork length and weight of specimens. Levels of Hg and Se in muscle and liver among years varied significantly (p < 0.05); although there was not a defined pattern of temporal fluctuations for both elements, the lowest Hg levels occurred in 2009 when surface water temperatures were the highest for the sampled years. With respect to the Se health benefit value (HBVSe), results were positive and above the unit in all cases; it implies that consumption of dolphinfish in the southern Gulf of California is beneficial.

Responses of soil nutrients and microbial communities to intercropping medicinal plants in moso bamboo plantations in subtropical China Abstract Bamboo forests are one of the most important forest resources in subtropical China. A pure, single-layer bamboo forest is considered an optimal habitat for intercropping medicinal herbs. Soil microorganisms have an important role in various ecological processes and respond quickly to environmental changes. However, changes in soil nutrients and microbial communities associated with agroforestry cultivation methods remain poorly documented. In the present study, a pure moso bamboo (Phyllostachys edulis) forest (Con) and three adjacent moso bamboo–based agroforestry (BAF) systems (moso bamboo–Paris polyphylla (BP), moso bamboo–Tetrastigma hemsleyanum (BT) and moso bamboo–Bletilla striata (BB)) were selected; and their soil chemical properties and bacterial communities were studied and compared to evaluate the effects of agroforestry on soil bacterial communities and the relationship between soil properties and bacterial communities in BAF systems. Results showed that compared with soils under the Con, soils under the BAF systems had more (p < 0.05) soil organic carbon (SOC) and available nitrogen (AN) but lower (p < 0.05) pH and available potassium (AK). In addition, compared with the Con system, the BB and BT systems had significantly greater (p < 0.05) available phosphorus (AP). Compared with that in the Con system, the Shannon index in the BAF systems was significantly greater (p < 0.05), but the Chao1 index not different. On the basis of relative abundance values, compared with the Con soils, the BAF soils had a significantly greater abundance of (p < 0.05) Bacteroidetes and Planctomyces but a significantly lower abundance of (p < 0.05) Verrucomicrobia, Gemmatimonadetes and Candidatus Xiphinematobacter. Moreover, compared with the Con system, the BB and BT systems had a greater (p < 0.05) abundance of Actinobacteria, Rhodoplanes, Candidatus Solibacter and Candidatus Koribacter. Redundancy analysis (RDA) revealed that soil pH, SOC and AP were significantly correlated with bacterial community composition. Results of this study suggest that intercropping medicinal herbs can result in soil acidification and potassium (K) depletion; thus, countermeasures such as applications of K fertilizer and alkaline soil amendments are necessary for BAF systems.

Distribution, residue level, sources, and phase partition of antibiotics in surface sediments from the inland river: a case study of the Xiangjiang River, south-central China Abstract In view of the increasing attention on antibiotic contamination and their scarce data in the inland river (especially for the sediment), the occurrence of 28 antibiotics in sediments from the Xiangjiang River was comprehensively analyzed, and 22 antibiotics were detected with a total concentration ranging from 4.07 to 2090 ng g−1. The residue was almost at a moderate or higher level in the aquatic environment around the world. Fluoroquinolones and tetracyclines were the dominant detected antibiotics, and the maximum total concentration could reach to 2085 ng g−1, though that in surface water was just 33.4 ng L−1. Oxytetracycline and chlortetracycline could be detected with high concentration in areas with lower population density. Usage profile of each antibiotic may be responsible for the spatial variation. Principal component analysis-multiple linear regression model indicated that direct discharge of domestic wastewater and livestock or aquaculture sewage could contribute 94.2% of the pollution. Redundancy analysis was used to screen out the environment variables, which were closely related to the pseudo-partitioning coefficients (Kd) of antibiotics in sediment and surface water for the first time, and showed that the Kd was correlated with sediment pH negatively and organic carbon, total phosphorus, and conductivity of the sediments positively. High sedimentary organic carbon was considered to promote the higher Kd in this river. This study would deepen the understanding of the occurrence of antibiotics in sediments from the inland rivers and provide scientific support for controlling the antibiotic contamination.

Effect of organic matter derived from algae and macrophyte on anaerobic ammonium oxidation coupled to ferric iron reduction in the sediment of a shallow freshwater lake Abstract As a recently discovered process of nitrogen cycling, anaerobic ammonium oxidation coupled to ferric iron reduction (Feammox) has attracted more attentions. This study investigated the spatial variation of Feammox in the sediment of different zones of a shallow freshwater lake and the effect of organic matter derived from algae and macrophyte on Feammox process. The potential Feammox rates showed significant differences among sediments from algae-dominated area (ADA), transitional area in the center of the lake (TDA), and macrophyte-dominated area (MDA), and in a descending order, ADA, MDA, and TDA. The potential Feammox rate ranged from 0.14 to 0.34 mg N kg−1day−1 in the freshwater lake sediment. The potential Feammox rates of the sediment with algae or macrophyte amendment were 12.29% and 15.31% higher than the control test without algae and macrophyte amendment. The addition of algae or macrophyte to the sediment from TDA could improve the amount of HCl-extractable total Fe, Fe(III) reduction rate, and the abundance of FeRB. These results demonstrated that organic matter is one of the key regulators of Feammox process.

The relationship between cement production, mortality rate, air quality, and economic growth for China, India, Brazil, Turkey, and the USA: MScBVAR and MScBGC analysis Abstract The related literature reveal that the papers on environmental pollution do not sufficiently analyse the cement production which is an important determinant of air pollution and health problems by using econometric methods. To fill this gap, this paper aims to examine the relationship between cement production, air pollution, mortality rate, and economic growth by employing MS Bayesian Vector Autoregressive (MScBVAR) and Markov Switching Bayesian Granger causality (MScBGC) approaches from 1960 to 2017 for China, Brazil, India, Turkey and the USA. MSIA(2)-BVAR(1) model for China, MSIAH(2)-BVAR(3) models for India, MSIAH(3)-BVAR(2) for Brazil, and MSIAH(3)-BVAR(1) for Turkey, and MSIAH(2)-BVAR(2) for the USA were selected. The MScBGC results revealed that the cement production is granger cause of mortality rate, air pollution, and economic growth in all regimes for China, India, Brazil, Turkey, and the USA.

Environmental impacts of chemical and microbial grouting Abstract Climate change is considered the major environmental challenge for the world. Cement and lime production is a highly energy-consuming, heavily polluting process, and the CO2 emissions are very substantial. Alkaline environment, high temperature, and long processing time lead the researchers to work on alternative soil improvements. Microbially induced calcite precipitation (MICP) has been introduced as a technique for modification of geotechnical properties of sand. The main purpose of the present study was to focus on the efficiency and environmental impact of conventional and microbial grouting. Samples were treated with three chemical stabilizers, namely Portland cement, lime, and cement and lime. The stabilizers were injected with flow gravity and constant head which are almost the same as microbial grouting. Then, the results of conventional grouting were compared with the results of biocement samples which were gathered from previous studies to discuss the efficiency and environmental impacts. The results for treated samples were discussed and compared based on 1 m3 of soil and a final target of 700 kPa. It was found that in order to obtain the same compressive strength, the cost and calcium carbonate consumption of the cement injection method were 2.5 times more than those of the microbial method. Biocementation has some advantages over existing technologies, such as less calcium usage in the same unconfined compressive strength (UCS).

Application of emulsion and Pickering emulsion liquid membrane technique for wastewater treatment: an overview Abstract According a wide range of relevant literature, the emulsion liquid membrane technique (ELM) is considered an efficient method to separate and recover organic and inorganic contaminants that could otherwise be released into the environment. One important limitation of ELM process concerns the stabilization and de-stabilization of emulsion globules. To address this, over the last few years, a new ELM trend known as the Pickering emulsion liquid membrane (PELM) has been developed. PELM involves nanoparticle concepts to achieve a more stable emulsion for wastewater treatment. In this article, ELM and PELM techniques, preparation methods, characteristics, stabilization methods (i.e., mechanical and ultrasound emulsification), and de-stabilization (i.e., swelling, leakage and coalescence) of the emulsion are reviewed and described. In addition, various parameters that could impact ELM stability, extraction, and recovery, such as emulsification speed and time, surfactant, carrier, internal agent, diluent, stirring speed, internal to membrane ratio, type of organic membrane, and treatment ratio, are also presented and discussed.