Arsenic (As) contamination is a global problem. Straw incorporation is widely performed in As contaminated paddy fields. To understand how straw and straw biochar incorporation affect As transformation and translocation in the soil-microbe-rice system, a pot experiment was carried out with different dosages of rice straw and straw biochar application. Results showed that both straw biochar and straw application significantly increased As mobility. Straw biochar mobilized As mainly through increasing soil pH and DOM content. Straw incorporation mainly through enhancing As release from iron (Fe) minerals and arsenate (As(V)) reduction to arsenite (As(III)). Straw biochar didn't significantly affect As methylation, while straw incorporation significantly enhanced As methylation, elevated dimethylarsenate (DMA) concentration in soil porewater and increased As volatilization. Straw biochar didn't significantly change total As accumulation in rice grains, but decreased As(III) accumulation by silicon (Si) inhibition. Straw incorporation significantly increased DMA, but decreased As(III) concentration in rice grains. After biochar application, dissolved As was significantly positively correlated with the abundance of Bacillus, indicating that Bacillus might be involved in As release, and As(III) concentration in polished grains was negatively correlated with Si concentration. The significant positive correlation between dissolved As with Fe and the abundance of iron-reducing bacteria suggested the coupling of As and Fe reduction mediated by iron-reducing bacteria. The significant positive correlation between DMA in rice grains and the abundance of methanogenic bacteria indicated that methanogenic bacteria could be involved in As methylation after straw application. The results of this study would advance the understanding how rice straw incorporation affects As fate in soil-microbe-rice system, and provide some guidance to straw incorporation in As contaminated paddy soil. This study also revealed a wealth of microorganisms in the soil environment that dominate As mobility and transformation after straw incorporation.

Chemical composition and pollutant sorption of biochar-derived organic matter fractions (BDOMs) are critical for understanding the long-term environmental significance of biochar. Phenanthrene (PHE) sorption by the humic acid-like (HAL) fractions isolated from plant straw- (PLABs) and animal manure-based (ANIBs) biochars, and the residue materials (RES) after HAL extraction was investigated. The HAL fraction comprised approximately 50% of organic carbon (OC) of the original biochars. Results of XPS and 13C NMR demonstrated that the biochar-derived HAL fractions mainly consisted of aromatic clusters substituted by carboxylic groups. The CO2 cumulative surface area of BDOMs excluding PLAB-derived RES fractions was obviously lower than that of corresponding biochars. The sorption nonlinearity of PHE by the fresh biochars was significantly stronger than that of the BDOM fractions, implying that the BDOM fractions were more chemically homogeneous. The BDOMs generally exhibited comparable or higher OC-normalized distribution coefficients (Koc) of PHE than the original biochars. The PHE logKoc values of the fresh biochars correlated negatively with the micropore volumes due to steric hindrance effect. In contrast, a positive relationship between the sorption coefficients (Kd) of BDOMs and the micropore volumes was observed in this study, suggesting that pore filling could dominate PHE sorption by the BDOMs. The positive correlation between the PHE logKoc values of the HAL fractions and the aromatic C contents indicates that PHE sorption by the HAL fractions was regulated by aromatic domains. The findings of this study improve our knowledge of the evolution of biochar properties after application and its potential environmental impacts.

Numerous studies have documented the negative effects of ozone (O₃) on tree species in growing season, however, little is done in non-growing season. Three evergreen tree species, Phoebe bournei (Hemsl.) Yang (P. bournei), Machilus pauhoi Kanehira (M. pauhoi) and Taxus chinensis (Pilger) Rehd (T. chinensis), were exposed to non-filtered air, 100 nmol mol⁻¹ O₃ air (E1) and 150 nmol mol⁻¹ O₃ air (E2) in open-top chambers in subtropical China. In the entire period of experiment, O₃ fumigation decreased net photosynthesis rate (Pn) through stomatal limitation during the transition period from growing to non-growing season (TGN), and through non-stomatal limitation during the period of non-growing season (NGS) in all species tested. Meanwhile, O₃ fumigation reduced and delayed the resilience of Pn in all species tested during the transition period from non-growing to growing season (TNG). O₃ fumigation significantly decreased chlorophyll contents during NGS, whereas no obvious injury symptoms were observed till the end of experiment. O₃ fumigation induced increases in levels of malondialdehyde, superoxide dismutase, total phenolics and reduced ascorbic acid, and changes in four plant endogenous hormones as well in all species tested during NGS. During NGS, E1 and E2 reduced Pn by an average of 80.11% in P. bournei, 94.56% in M. pauhoi and 12.57% in T. chinensis, indicating that the O₃ sensitivity was in an order of M. pauhoi > P. bournei > T. chinensis. Overall, O₃ fumigation inhibited carbon fixation in all species tested during NGS. Furthermore, O₃-induced physiological activities also consumed the dry matter. All these suggested that elevated O₃, which is likely to come true during NGS in the future, will adversely affect the accumulation of dry matter and the resilience of Pn during TNG in evergreen tree species, and further inhibit their growth and development in the upcoming growing season.

Among Southeast Asian countries, Thailand has gradually accustomed to extremely prompt urbanization, motorization, and industrialization. Chonburi and Rayong provinces are two provinces involved in “eastern seaboard” industrial zones, which is an emerging economic region that plays a key role in Thailand's economy. The 2013 Rayong oil spill did not only cause damages to the coastal and maritime environment, but also undermine trust in the overall safety system and negatively affect the investor confidence. In this study, 69 coastal soils collected around Koh Samed Island were chemically extracted and analyzed for 15 PAHs by using a Shimadzu GCMS-QP2010 Ultra system comprising a high-speed performance system with ASSP function. In this study, numerous diagnostic binary ratios were applied to identify potential sources of PAHs. Advanced statistical techniques such as hierarchical cluster analysis coupled with principal component analysis were also conducted for further investigations of source identifications.

Exposure to traffic-related PM₂.₅ mass and its components can affect human health. Meanwhile, indoor concentrations are better exposure predictors as compared to outdoor concentrations because individuals spend the majority of their time indoors. We estimated the impact of traffic emissions on indoor PM₂.₅ mass and its species as a function of road proximity in Massachusetts. A linear regression model was built using 662 indoor samples and 580 ambient samples. Analysis shows that indoor exposures to traffic-related particles increased dramatically with road proximity. We defined relative concentration decrease, R(α), as the ratio of the indoor concentration at perpendicular distance α in meters from the closest major road to the indoor concentration at 1800 m from the major road. R(13) values for PM₂.₅ mass and Black Carbon (BC) were 1.3 (95%CI: 1.4, 1.6) and 2.1 (95%CI: 1.3, 2.8) for A12 roads, and 1.3 (95%CI: 1.2, 1.4) and 1.2 (95%CI: 1.1, 1.3) for A3 roads. R(α) values were also estimated for Fe, Mn, Mo, Sr and Ti for A12 roads, and Ca, Cu, Fe, Mn, Mo, Ni, Si, Sr, V and Zn for A3 roads. R(α) values for species associated mainly with brakes, tires or road dust (e.g., Mn, Mo and Sr) were higher than others. For A12 roads, R(13) values for Mn and Mo were 10.9 (95%CI: 0.9, 20.9) and 6.5 (95%CI: 1.4, 11.5), and ranged from 1.3 to 2.1 for other species; for A3 roads, R(13) values for Mn, Mo and Sr were 1.9 (95%CI: 1.1, 2.9), 1.8 (95%CI: 1.1, 2.4), and 8.5 (95%CI: 5.9, 10.9), and ranged from 1.2 to 1.6 for others. Our results indicate a significant impact of local traffic emissions on indoor air, which depends on road proximity. Thus road proximity which has been used in many epidemiological studies is a reasonable exposure metric.

Heavy metals deposited on urban road surfaces can be washed-off by stormwater runoff, undermining stormwater reuse safety due to their high toxicity to ecological and human health. Heavy metals on urban road surfaces come from diverse sources and tracking these sources is essential to effectively manage stormwater and hence its reuse safety. This research study developed an innovative approach to tracking sources of heavy metals using data collected in Shenzhen, China. This approach developed was based on a “flag element ratio” theory, where each source generally corresponds to a specific ratio of targeted pollutants to the flag element. It is noted that Cr, Cu, Pb, Ni, and Zn on urban roads were 19.05 mg/kg to 152.01 mg/kg, 25.66 mg/kg to 310.75 mg/kg, 15.61 mg/kg to 220.35 mg/kg, 10.65 mg/kg to 100.28 mg/kg, and 138.14 mg/kg to 1047.05 mg/kg, respectively. Gasoline emission was the main source for Cr, Ni and Pb, while braking wear and tyre wear were the major sources of Cu and Zn, respectively. Furthermore, the rankings of sources of each heavy metal in terms of their contributions were obtained by using this approach. Vehicle exhaust was found as the main contributor for all the heavy metals on urban road surfaces. This highlighted that vehicle exhaust should be seriously considered in terms of controlling heavy metal pollution on urban road surfaces and hence resulting urban road stormwater runoff.

Fungi are well associated with the degradation of hydrocarbons by the production of different enzymes, among which catalases (CBH), laccases (LCC) and peroxidases (LiP and MnP) are of immense importance. In this study, crude oil tolerance and enzyme secretions were demonstrated by rhizospheric fungal strains. Four most abundant strains were isolated from the rhizosphere of grasses growing in aged oil spill sites and identified through morphological characterization and molecular PCR-amplification of 5.8–28S ribosomal rRNA using ITS1 and ITS4 primers. These strains were subjected to crude oil tolerance test at 0–20% concentrations. Presence and transcriptase responses of putative genes lig (1–6), mnp, cbh (1.1, 1.1 and 11), and lcc encoding lignin peroxidase, manganese peroxidase, catalase, and laccase enzymes respectively were also studied in these strains using RT-PCR. In addition, activities of secreted enzymes by each strain were studied in aliquots. The strains were identified as Aspergillus niger asemoA (KY473958), Talaromyces purpurogenus asemoF (KY488463), Trichoderma harzianum asemoJ (KY488466), and Aspergillus flavus asemoM (KY488467) through sequencing and comparing the sequences’ data at NCBI BLAST search software. All the isolated strains showed tolerance to crude oil at 20% concentration, but the growth rate reduced with increasing in oil concentrations. All the isolated strains possess the tested genes and lig 1–6 gene was overexpressed in A. niger and T. harzianum while lcc and mnp genes were moderately expressed in all the four strains. Almost 145 U.mL⁻¹ of lignin and manganese peroxidase, 87 U.mL⁻¹ of catalase, and 180 U.mL⁻¹ of laccase enzymes were produced by these strains and it was also observed that these strain mostly produced studied enzymes in response to increasing crude oil concentrations. Considering the robust nature and diverse production of these catalytic enzymes by these strains, they can be exploited for various bioremediation technologies as well as other biotechnological applications.

Zinc oxide nanoparticles (ZnO NPs) have a wide range of applications in cosmetics, electrical, and optical industries. The wide range of applications of ZnO NPs, especially in personal care products, suggest they can reach major environmental matrices causing unforeseen effects. Recent literature has shown conflicting findings regarding the beneficial or detrimental effects of ZnO NPs towards terrestrial biota. In this review we carried out a comprehensive survey about beneficial, as well as detrimental aspects, of the ZnO NPs exposure toward various terrestrial plants. A careful scrutiny of the literature indicates that at low concentrations (about 50 mg/kg), ZnO NPs have beneficial effects on plants. Conversely, at concentrations above 500 mg/kg they may have detrimental effects, unless there is a deficiency of Zn in the growing medium. This review also remarks the critical role of the biotic and abiotic factors that may elevate or ameliorate the impact of ZnO NPs in terrestrial plants.

Agriculture-based climate change mitigation may occur through enhancing the carbon sink or through reducing greenhouse gases (GHGs) emissions from agricultural residue treatment, as open burning of agricultural residues produces millions of tons of GHGs and air pollutants annually worldwide. Charring slashed biomass, termed as slash-and-char, has been considered as a promising alternative to open burning in dealing with agricultural residues such as rice straw. Previous studies, however, focused on relatively sophisticated slash-and-char systems, which could not be practiced easily by smallholder farmers in developing countries. Here we introduce a simple slash-and-char system to mitigate the environmental problems associated with open burning of rice straw. This system could convert 30.7% of the initial carbon in rice straw into biochar, much higher than that retained in the ash generated by open burning (3.95%). It could also cut GHGs, particulate matters and polycyclic aromatic hydrocarbons (PAHs) emissions by 26.9%, 99.0% and 99.4%, respectively. If open burning of rice straw was replaced by the slash-and-char, the annual emissions of GHGs, particulate matters and PAHs in China would decrease by at least 15.4 Tg, 1.51 Tg and 1.27 Gg, correspondingly. This decrease is nearly twice the size of China's estimated forest C sink (8.81 Tg).

Glyphosate (GLY) is one of the most used herbicide worldwide. Considering that information concerning the impact of GLY on bivalves is scarce, in this study we evaluated for the first time the effects of environmentally realistic concentrations of GLY (10, 100 and 1000 μg/L) to the mussel Mytilus galloprovincialis. Mussels were exposed for 7, 14 and 21 days and several biomarkers were measured in haemocytes/haemolymph (total haemocyte counts, haemocyte diameter and volume, haemolymph pH, haemolymph lactate dehydrogenase activity, haemocyte lysate lysozyme and acid phosphatase activities), as well as in gills and digestive gland (antioxidant enzyme and acetylcholinesterase activities). The concentrations of GLY and its main metabolite aminomethylphosphonic acid in the experimental tanks were also measured. The MANOVA analysis demonstrated that the experimental variables considered (exposure concentration, exposure duration, and their interaction) affected significantly biomarker responses. In addition, the two-way ANOVA analysis indicated that GLY was able to affect most of the cellular parameters measured, whereas antioxidant enzyme activities resulted to be influenced moderately. Interestingly, exposure to GLY reduced significantly acetylcholinesterase activity in gills. Although preliminary, the results of this study demonstrated that GLY can affect both cellular and biochemical parameters in mussels, highlighting a potential risk for aquatic invertebrates.