Plants have the ability to adapt themselves under stressed conditions through reprogramming their growth and development. Understanding the mechanisms regulating overall growth of stressed plant is an important issue for plant and environmental biology research. Although the role of NO in modulating arsenic (As) toxicity is known, nitric oxide (NO) induced alteration in auxin and nutrient related transporters during As stress in rice is poorly understood. Experimental results showed that As exposure decreased gene expression level of polar auxin transporter (PIN proteins), and nutrient transporter related genes (AMT, NRT, NiR, PHT, KTP). The improved tolerance induced by As + NO combination is attributed to reduced As accumulation in rice seedlings, improved root architectural changes, overall growth of plant, chlorophyll, protein content, and accumulation of mineral nutrients by reducing the ROS generation. Further, enhanced transcript levels of PIN proteins and mineral nutrition related genes were also observed under As + NO treatment. Additional biochemical data revealed enhanced oxidative stress by increasing the level of antioxidant enzymes, and stress-related parameters. Overall, the study provides an integrated view of plant response during As + NO interaction to change the plant metabolism through different cellular processes.

Rapid urbanization and economic growth has led to significant increase in municipal solid waste generation in India during the last few decades and its management has become a major issue because of poor waste management practices. Solid waste generated is deposited into open dumping sites with hardly any segregation and processing. Carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) are the major greenhouse gases that are released from the landfill sites due to the biodegradation of organic matter. In this present study, CH₄ and CO₂ emissions from a landfill in north-east India are estimated using a flux chamber during September, 2015 to August, 2016. The average emission rates of CH₄ and CO₂ are 68 and 92 mg/min/m², respectively. The emissions are highest in the summer whilst being lowest in winter. The diurnal variation of emissions indicated that the emissions follow a trend similar to temperature in all the seasons. Correlation coefficients of CH₄ and temperature in summer, monsoon and winter are 0.99, 0.87 and 0.97, respectively. The measured CH₄ in this study is in the range of other studies around the world. Modified Triangular Method (MTM), IPCC model and the USEPA Landfill gas emissions model (LandGEM) were used to predict the CH₄ emissions during the study year. The consequent simulation results indicate that the MTM, LandGEM-Clean Air Act, LandGEM-Inventory and IPCC models predict 1.9, 3.3, 1.6 and 1.4 times of the measured CH₄ emission flux in this study. Assuming that this higher prediction of CH₄ levels observed in this study holds well for other landfills in this region, a new CH₄ emission inventory (Units: Tonnes/year), with a resolution of 0.1⁰ × 0.1⁰ has been developed. This study stresses the importance of biodegradable composition of waste and meteorology, and also points out the drawbacks of the widely used landfill emission models.

Hexabromocyclododecane (HBCD), a ubiquitous suspected contaminant, is one of the world's most prominent brominated flame retardants (BFRs). In the present study, earthworms (Eisenia fetida) were exposed to HBCD. The expression of selected antioxidant enzyme genes was measured, and the metabolic responses were assessed using nuclear magnetic resonance (NMR) to identify the molecular mechanism of the antioxidant stress reaction and the metabolic reactions of earthworms to HBCD. A significant up-regulation (p < 0.05) of superoxide dismutase (SOD) gene expression was detected, with the highest gene expression level of SOD appearing at a dose of 400 mg kg⁻¹ dw (2.06-fold, p < 0.01). However, the glutathione transferase (GST) gene expression levels did not differ significantly (p > 0.05). Principal component analysis (PCA) of the metabolic responses showed that all groups could be clearly differentiated, and the highest concentration dose group was the most distant from the control group. Except for fumarate, the measured metabolites, which included adenosine triphosphate (ATP), valine, lysine, glycine, betaine and lactate, revealed significant (p < 0.05) increases after 14 days of exposure to HBCD. HBCD likely induces high levels of anaerobic respiration, which would result in high levels of ATP and lead to the disintegration of proteins into amino acids, including valine and lysine, to produce energy. The observed changes in osmotic pressure were indicative of damage to the membrane structure. Furthermore, this study showed that NMR-based metabolomics was a more sensitive tool than measuring the gene expression levels for elucidating the mode of toxicity of HBCD in earthworm exposure studies.

The (un)intentional release of titanium dioxide nanoparticles (TiO₂ NPs) poses potential risks to the environment and human health. Phosphorus (P) and humic acid (HA) usually coexist in the natural environments. This study aims at investigating the transport and retention behaviors of TiO₂ NPs in the single and binary systems of P and HA in water-saturated porous media. The experimental results showed that HA alone favored the transport of TiO₂ NPs in sand columns to a greater extent than that of P alone at pH 6.0. Interestingly, the co-presence of P and HA acting in a synergistic fashion enhanced the transport of TiO₂ NPs in sand-packed columns more significantly compared to that in the single-presence of P or HA. Particularly, P plays a dominant role in the synergistic effect. This is largely due to the competitive effect between P and HA for the same adsorption sites on the sand surfaces favorable for TiO₂ NPs retention. A two-site kinetic attachment model that considers Langmuirian blocking of particles at one site provided a good approximation of TiO₂ NPs transport. Modeled first-order attachment coefficient (k₂) and the maximum solid-phase retention capacity on site 2 (Sₘₐₓ₂) for P or HA alone were larger than those in the co-presence of P and HA, suggesting a less retention degree of TiO₂ NPs in the binary system of P and HA. Our findings indicate that the mobility of TiO₂ NPs is expected to be appreciable in soil and water environments, where P and HA are rich and always co-present at low pH conditions.

Intermittent, fluctuating and pulsed contaminant discharges may result in organisms receiving highly variable toxicant exposures. This study investigated the toxicity of continuous and pulsed exposures of a complex, neutralised drainage water (NDW) and dissolved copper-spiked dilute NDW to the green alga, Pseudokirchneriella subcapitata. The effects of single pulses of between 1 and 48 h duration and continuous exposures (72 h) on algal growth rate inhibition were compared on a time-averaged concentration (TAC) basis. Algal growth rates generally recovered to control levels within 24–48 h of the pulse removal. Continuous exposures to NDW resulted in similar or marginally higher toxicity to the algae when compared to pulsed exposures of equivalent TAC (% NDW). The toxicity of the NDW was attributed mostly to the metals, with the major cations potentially causing effects that are both additive (direct toxicity) and antagonistic (lower bioavailability of trace metals). For dissolved copper in dilute NDW, the pulsed exposures caused slightly higher toxicity than continuous exposures of equivalent dissolved copper TAC, with much of the difference explained by differences in labile copper concentrations between treatments. The results indicate that water quality guideline values for toxicants derived from continuous chronic exposures may be relaxed for pulsed exposures by a factor related to the TAC with the intent to provide an adequately protective but not overly-conservative outcome. The study highlights the influence that natural water quality parameters such as water hardness and DOC can have metal speciation and toxicity, and indicates that these parameters are particularly important for site-specific water quality guideline value derivation where, on a TAC basis, pulsed exposures may be more toxic than continuous exposures typically used in guideline value derivation.

Ground-level ozone (O3) concentrations have been elevating in the last century. While there has been a notable progress in understanding O3 effects on vegetation, O3 effects on ecological stoichiometry remain unclear, especially early in the oxidative stress. Ethyelenediurea (EDU) is a chemical compound widely applied in research projects as protectant of plants against O3 injury, however its mode of action remains unclear. To investigate O3 and EDU effects early in the stress, we sprayed willow (Salix sachalinensis) plants with 0, 200 or 400 mg EDU L−1, and exposed them to either low ambient O3 (AOZ) or elevated O3 (EOZ) levels during the daytime, for about one month, in a free air O3 controlled exposure (FACE); EDU treatment was repeated every nine days. We collected samples for analyses from basal, top, and shed leaves, before leaves develop visible O3 symptoms. We found that O3 altered the ecological stoichiometry, including impacts in nutrient resorption efficiency, early in the stress. The relation between P content and Fe content seemed to have a critical role in maintaining homeostasis in an effort to prevent O3-induced damage. Photosynthetic pigments and P content appeared to play an important role in EDU mode of action. This study provides novel insights on the stress biology which are of ecological and toxicological importance.

Marine litter is commonly observed everywhere in the ocean. In this study, we analyzed 17 km of video footage, collected by a Remotely Operated Vehicle (ROV) at depths ranging between 20 and 220 m, during 19 transects performed on the rocky banks of the Straits of Sicily. Recently, the Contracting Parties of the Convention on Biological Diversity (CBD) recognized this site as an Ecologically or Biologically Significant Area (EBSA). The research aim was to quantify the abundance of marine litter and its impact on benthic fauna. Litter density ranged from 0 items/100 m2 to 14.02 items/100 m2 with a mean (±standard error) of 2.13 (±0.84) items/100 m2. The observed average density was higher (5.2 items/100 m2) at depths >100 m than at shallower depths (<100 m, 0.71 items/100 m2). Lost or abandoned fishing lines contributed to 98.07% of the overall litter density, then representing the dominant source of marine debris. Litter interactions with fauna were frequently observed, with 30% of litter causing “entanglement/coverage” and 15% causing damage to sessile fauna. A total of 16 species showed interaction (entanglement/coverage or damage) with litter items and 12 of these are species of conservation concern according to international directives and agreements (CITES, Berne Convention, Habitat Directive, SPA/BD Protocol, IUCN Red List); we also observed 7 priority habitats of the SPA/BD Protocol. This research will support the implementation of monitoring “Harm” as recommended by the UN Environment/MAP Regional Plan on Marine Litter Management in the Mediterranean, and the Marine Strategy Framework Directive (MSFD). The institution of a SPAMI in the investigated area could represent a good management action for the protection of this hotspot of biodiversity and to achieve a Good Environmental Status (GES) for the marine environment by 2020, under the MSFD.

Atrazine (ATR), a selective herbicide, is consistently used worldwide and has been confirmed to be harmful to the health of aquatic organisms. The release of neutrophil extracellular traps (NETs) is one of the newly discovered antimicrobial mechanisms. Although several immune functions have been analyzed under ATR exposure, the effect of ATR on NETs remains mainly unexplored. In the present study, we treated carp neutrophils using 5 μg/ml ATR and 5 μg/ml ATR combined with 100 nM rapamycin to elucidate the underlying mechanisms and to clarify the effect of ATR on phorbol myristate acetate (PMA)-induced NETs. The results of the morphological observation and quantitative analysis of extracellular DNA and myeloperoxidase (MPO) showed that NETs formation were significantly inhibited by ATR exposure. Moreover, we found that in the NETs process, ATR downregulated the expression of the anti-apoptosis gene B-cell lymphoma-2 (Bcl-2), increased the expression of the pro-apoptosis factors Bcl-2-Associated X (BAX), cysteinyl aspartate specific proteinases (Caspase3, 9), and anti-autophagy factor mammalian target of rapamycin (mTOR), decreased the expression of autophagy-related protein light chain 3B (LC3B) and glucose transport proteins (GLUT1, 4), disturbed the activities of phosphofructokinase (PFK), pyruvate kinase (PKM), and hexokinase (HK) and limited reactive oxygen species (ROS) levels, indicating that the reduced NETs release was a consequence of increased apoptosis and diminished ROS burst, autophagy and down-regulated glycolysis under ATR treatment. Meanwhile, rapamycin restored the inhibited autophagy and glycolysis and thus resisted the ATR-suppressed NETs. The present study perfects the mechanism theory of ATR immunotoxicity to fish and has a certain value for human health risk assessment.

Following the recent progress in magnetic nanotechnology, concern over the optimal benefits and potential risks of iron oxide nanoparticles (Fe NPs), has increased. Hence, to minimize the negative impacts of inorganic Fe NPs, we report the phyco-synthesis and characterization of superparamagnetic Fe3O4 NPs via reduction of ferric/ferrous chloride solution (2:1 M ratio; 88 °C) with green macroalga, Ulva flexuosa (wulfen) J.Agardh aqueous extract. The biogenic process is clean, eco-friendly, rapid, and facile to handle. These green fabricated magnetite NPs are characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), particle size analysers (PSA), zeta potential (ZP) measurement, and vibrating sample magnetometry (VSM) techniques. The results confirmed that the cubo-spherical, polydisperse of biosynthesized Fe3O4 NPs with an average diameter of 12.3 nm was formed. The antagonistic effects of algal extract, chemo-route and U. flexuosa-derived Fe3O4 MgNPs on selective human pathogenic microbes (i.e. n = 11) resulted in strong antibacterial and moderate antifungal activity. The comparative toxic and reproductive effects of the chemo- and bio-routes of Fe3O4-MgNPs against rotifer B. rotundiformis exhibited low acute toxicity with a lower inducing effect of biogenic nano-magnetite on reduction rotifer reproductive rate than its chemogenic counterpart. In view of the nanoecotoxicity, though the current study covered a wide range of exposure concentrations (10-500 mg/L) of organic and inorganic nano sizes of Fe3O4 in brackish water rotifer, a biotoxicity assay at higher dosage or a comprehensive risk assessment in different aqua-organisms is recommended.

Poor indoor air quality can have adverse effects on human health, especially in susceptible populations; however, few studies have measured multiple pollutants in facilities for susceptible populations at a national scale in South Korea. Therefore, we measured the concentrations of indoor pollutants (fine particulate matter (PM₁₀), CO₂, airborne bacteria (AB), total volatile organic compounds (TVOCs), and formaldehyde) to determine their possible relation to other indoor environmental factors and characteristics of facilities with susceptible populations, such as hospitals, geriatric hospitals, elderly care facilities, and postnatal care centers throughout South Korea. Indoor pollutants were sampled at 82 indoor facilities, including 62 facilities for susceptible populations. Spearman's correlation, Kruskal–Wallis, and Mann–Whitney analyses were used to examine the relationship among and differences between pollutants at indoor facilities and indoor/outdoor differences in PM₁₀ concentration. There were significant correlations between indoor temperature and AB concentration (r = 0.37, p < 0.01), TVOCs, and formaldehyde (r = 0.264, p < 0.01). Indoor PM₁₀ concentrations were higher than outdoor concentrations at all facilities for susceptible populations (p < 0.01). CO₂ might be a good indicator for predicting indoor pollutants when categorized into two levels (≤750 ppm and >750 ppm). The hazard quotient of formaldehyde was higher than the acceptable level of 1 for children under the age of eight in postnatal care centers, indicative of unsafe levels. Therefore, more depth study for exposure characteristics of formaldehyde and indoor air quality (IAQ) in postnatal care facilities as a national scale is needed for finding the children exposure levels.