Arsenic (As) is one of the most toxic and cancer-causing metals which is generally entered the food chain via intake of As contaminated water or food and harmed the life of living things especially human beings. Therefore, the reduction of As content in the food could be of great importance for healthy life. To reduce As contamination in the soil and food, the evaluation of plant-based As uptake and transportation mechanisms is critically needed. Different soil factors such as physical and chemical properties of soil, soil pH, As speciation, microbial abundance, soil phosphates, mineral nutrients, iron plaques and roots exudates effectively regulate the uptake and accumulation of As in different parts of plants. The detoxification mechanisms of As in plants depend upon aquaporins, membrane channels and different transporters that actively control the influx and efflux of As inside and outside of plant cells, respectively. The xylem loading is responsible for long-distance translocation of As and phloem loading involves in the partitioning of As into the grains. However, As detoxification mechanism based on the clear understandings of how As uptake, accumulations and translocation occur inside the plants and which factors participate to regulate these processes. Thus, in this review we emphasized the different soil factors and plant cell transporters that are critically responsible for As uptake, accumulation, translocation to different organs of plants to clearly understand the toxicity reasons in plants. This study could be helpful for further research to develop such strategies that may restrict As entry into plant cells and lead to high crop yield and safe food production.

Microplastics (MPs) pollution frequently co-occur with Microcystis-dominated blooms in freshwaters, but MPs effects on toxigenic Microcystis growth and effect mechanisms remained poorly understood. This study used 0.5 μm-size polyethylene (PE) and polyvinyl chloride (PVC) to explore dose- and time-dependent effects of single and combined MPs (i.e., PE + PVC) on toxigenic Microcystis growth and cellular responses during 16 day-test. Results showed that Microcystis growth and cellular responses depended on exposure time, MPs dose and type. MPs elicited hormesis effect in early stage at low dose (5 mg/L), while increasingly inhibited growth with rising PVC or PE + PVC dose but declining PE dose (5, 10, 50 mg/L) in mid-late stage, with stress intensity of PE + PVC > PVC > PE. Further analyses revealed unobvious cell damage under MPs stress, largely because antioxidases were increasingly activated as MPs stress enhanced. Unicellular MCs release ability during mid stage almost coincided with total/bound amount and each fraction of ex-poly and ex-pro trends under MPs stress. Significant positive relationship existed between MCs release ability and ex-poly/ex-pro fractions and total amount of Microcystis cells along mid-late stage under MPs stress, validating that ex-poly/ex-pro production was regulated as a result of MCs release. Besides, unicellular MCs production ability was generally positively correlated with soluble, tightly-bound and total ex-poly and ex-pro at late stage. These suggested that cellular antioxidants, MCs production/release ability and ex-poly/ex-pro production of Microcystis could be coupled to exert integrated defense against MPs stress to protect surviving cells in Microcystis population. These findings are crucial for acquiring the fate of Microcystis-dominated blooms co-occurring with MPs pollution, and reasonably assessing and managing involved eco-risks.

Organochlorine pesticides (OCPs) are well known synthetic pesticides widely used in agricultural practices and public health program. Higher toxicity, slow degradation, and bioaccumulation are the significant challenges of OCPs. Due to its uses in agricultural and public health, contamination of drinking water and water table also increases day by day. Contaminated drinking water has become a significant issue and alarming signal for public health globally. The purpose of this study was to assess the recent trend of organochlorine pesticides (OCPs) level in drinking water and blood samples of the North Indian population and also to find out its association with glucose intolerance, lipid metabolism, and insulin resistance, which are known risk factors of type 2 diabetes mellitus (T2DM). A case-control study was conducted on 130 Non-Glucose intolerance (NGT), 130 pre-diabetes and 130 recently diagnosed T2DM subjects of the age group of 30–70 years. Patients consuming drinking water from the same source for at least ten years were included in this study for blood and water samples collection. Significantly higher levels of α-HCH, β-HCH, γ-HCH, p,p’-DDE, and o,p’-DDT were found in groundwater samples. However, in tap water samples, the level of α-HCH was found to be slightly higher than the permissible limit of 0.001. Among all recruited subjects consuming contaminated groundwater, 42% had T2DM, 38% pre-diabetes, and the remaining 20% were found normal. We also observed that OCP contamination in groundwater is higher than tap and filter water. The levels of β-HCH, p,p’-DDE, and o,p’-DDT were higher in the pre-diabetes and T2DM group than the NGT group. With an increase of OCPs level in groundwater, the blood OCPs level tends to increase T2DM risk. It depicts that the elevated OCPs level in consumed groundwater may contribute to increased risk for the development of T2DM after a certain period of exposure.

Effluent discharges can potentially result in high concentrations of metals entering aquatic environments for short durations, ranging from a few hours to days. The environmental risks of such exposures are challenging to accurately assess. Risk assessment tools for effluent discharges include comparison of toxicant concentrations with guideline values and the use of direct toxicity assessments, both of which were designed to assess continuous, rather than pulse, contaminant exposures. In this study, a chronic pulse-exposure toxicity test was developed using the tropical euryhaline calanoid copepod Acartia sinjiensis. This copepod has a rapid life cycle and is highly sensitive to metal contaminants, with 50% effect concentrations (chronic EC50) for larval development of 1.7, 8.6 and 0.7 μg L⁻¹ for copper, nickel and zinc, respectively. The toxicities of copper and nickel were assessed as a continuous exposure (78 h) and as pulses (3, 6 and 18 h) initiated at varying life stages, from egg to copepodite, and measured larval development over 78 h. Generally, 24-h old nauplii were more sensitive or of similar sensitivity to copper and nickel pulses than 48-h old nauplii. The 78-h test duration enabled observations of chronic effects following pulse exposures, which frequently occurred in the absence of acute effects. The EC50 values for pulse exposures were higher than those of continuous exposure by up to approximately 16-fold and 15-fold for copper and nickel, respectively. When metal-pulse exposure concentrations were expressed using the time-weighted averaged concentration (TAC), resultant concentration response curves were similar to those in continuous exposures to the same metal, suggesting that thresholds based on continuous exposures were also protective for pulse exposures to these metals. This research improves our understanding of the toxicity of pulse contaminant exposures and assists with developing improved approaches to for the risk assessment and regulation of short-term contaminant discharges.

The relationship between heavy metal(loid)s exposure and oxidative stress damage is a matter of research interest. Our study aimed to investigate the distribution patterns of the nine heavy metal(loid)s in blood of pregnant women, including four toxic heavy metal(loid)s [arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg)] and five typical heavy metal(loid)s [manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), and selenium (Se)] in blood. Blood samples of 348 women were collected and their concentrations in the serum (sr) and blood cells (bc) were measured, as well as serum heme oxygenase-1 (HO-1) (an oxidative stress marker). Total blood (tb) concentrations of these metal(loid)s and serum-to-blood cell concentration ratios (sr/bc) were further calculated. We found Cu mainly accumulated in the serum compared to the blood cells with Cuˢʳ/ᵇᶜ = 2.30, whereas Co, Se, and As evenly distributed between these two fractions. Other metal(loid)s mainly concentrated in the blood cells. Coˢʳ, Cuˢʳ, Cuᵇᶜ, Mnᵇᶜ, Znᵇᶜ, Cdᵇᶜ, Coᵗᵇ, Cuᵗᵇ, Mnᵗᵇ, Znᵗᵇ, Cdᵗᵇ, and Cuˢʳ/ᵇᶜ were negatively associated with serum HO-1, whereas Asˢʳ, Asᵇᶜ, Asᵗᵇ, Znˢʳ/ᵇᶜ, Cdˢʳ/ᵇᶜ, and Hgˢʳ/ᵇᶜ were positively, indicating of their potential toxicity. We concluded that the distribution patterns of blood heavy metal(loid)s, in particular for Cd, Hg and Zn, which either increased in serum or decreased in blood cells, might be associated with elevated serum oxidative stress, should be considered in environmental health assessments.

or sugar-derived compounds were used as environmentally friendly additives for the depolymerization of Kraft lignin waste and organosolv lignin prepared from Miscanthus giganteus. The yields of the aromatic monomers obtained from Kraft lignin increased from 5.1 to 49.2% with the addition of mannitol, while those obtained from organosolv lignin increased from 44.4 to 83.0% with the addition of sucrose. This improved lignin depolymerization was also confirmed by gel permeation chromatography and nuclear magnetic resonance spectroscopy. The above results clearly indicate the beneficial effects of carbohydrate derivatives on the lignin depolymersization process, more specifically, suggesting that the presence of carbohydrates improve the lignin depolymerization of lignocellulose, as observed for the raw lignocellulose feed.

Polyethylene film is one of the most common types of recalcitrant plastic waste materials. Information regarding the fate of plastic films in soil is scarce compared to the fate of plastic films in aquatic environments. The aim of this study was to evaluate the effects of soil fauna and of impregnation of polyethylene films with oil on the colonization of low-density polyethylene films by prokaryotic communities. The field experiment was performed in a monsoon tropical forest (Vietnam). Polyethylene films were incubated in thermally pre-defaunated soil isolated from the surrounding soil by a stainless steel mesh. Three mesh sizes were used, allowing access to different size groups of soil fauna. The diversity, taxonomic structure and co-occurrence patterns in prokaryotic communities were studied using high-throughput sequencing of 16S rRNA gene libraries. The prokaryotic communities that formed on polyethylene films were slightly different from those inhabiting the surrounding soil. Contrary to our expectations, no difference in the diversity of prokaryotes was observed between microcosms with different mesh sizes. Oil impregnation also had only a minor influence on the prokaryotic community structure. Polyethylene films incubated in microcosms with soil appeared to be colonized by various consortia of prokaryotes as a barren and inert surface.

The acidogenic fermentation of dairy wastewater (DW) was evaluated for carboxylic acids (CA) production, investigating the influence of substrate/microorganism (S/X) ratio and applying different mathematical models to the bioproduct formation data. The experiments were performed in batch reactors for 28 days, and four S/X ratios were tested (0.8, 1.2, 1.6, and 1.9 gCOD gVSS⁻¹). The S/X ratio increase did not influence the percentage of DW conversion into carboxylic acids (42–44%), but the productivity was positively affected (100–200% in general). Acetic acid was the CA formed in the highest concentration for all experiments, followed by propionic and butyric acids. Exponential models were better suited to describe this kinetics process. Therefore, according to the estimated kinetic parameters, the S/X ratio 1.6 was more suitable for CA production from acidogenic fermentation of dairy wastewater, in which the concentrations of longer CA, such as propionate and butyrate, were formed in higher quantities. In addition, it was determined a correlation between the S/X ratio and kinetic parameters like degradation/production rate constant (K) and maximum productivity rate (μₘ).

The scale of variation in species sensitivity to toxicants has been theoretically linked to mode of action. Specifically, it has been proposed there will be greater variations for chemicals with a putative specific biological target than for toxicants with a non-specific narcotic mechanism. Here we test the hypothesis that mode of action is related to variation in sensitivity in a specifically designed experiment for species from a single ecologically important terrestrial taxa, namely earthworms. Earthworm toxicity tests were conducted with five species for four chemicals, providing a series of increasingly complex modes of action: a putative narcotic polycyclic aromatic hydrocarbon (fluoranthene), and three insecticides (chlorpyrifos, cypermethrin, imidacloprid) with known neuronal receptor targets. Across all the chemicals, the standard epigeic test species Eisenia fetida and Lumbricus rubellus, were generally among the two least sensitive, while the endogenic Aporrectodea caliginosa and Megascolecidae Amynthas gracilis were generally more sensitive (never being among the two least sensitive species). This indicates a potential for bias in the earthworm ecotoxicology literature, which is dominated by studies in epigeic Lumbricidae, but contains few endogeic or Megascolecidae data. Results confirmed the lowest range of variation in sensitivities for effects on reproduction was for fluoranthene (2.5 fold). All insecticides showed greater variation for species sensitivity (cypermethrin: 7.5 fold, chlorpyrifos: 10.3 fold, imidacloprid: 31.5 fold) consistent with the specific mechanisms of the pesticides. Difference in toxicodynamics, based on mode of action specificity and receptor complexity was reflected in the magnitude of sensitivity variation. However, measurements of tissue concentrations also indicated the potential importance of toxicokinetics in explaining species sensitivity variations for chlorpyrifos and cypermethrin.

Pathogenic survivals were dramatically affected by Fe³⁺ and Mn²⁺ under freeze-thaw (FT), and the dissolutions of manganese and iron oxides (MIOs) were also accelerated under FT. But the mutual influences of pathogenic bacterial survival and MIOs under FT have not been profoundly explored yet. In this work, aqueous systems containing Escherichia coli as well as synthetic ferrihydrite (Fh) and manganese dioxide (MnO₂) were experimented under simulated FT cycles to study the mutual influences of metal oxides and bacteria survival while oxide dissolutions and appearances, bacterial morphology and activities (survival number, cell surface hydrophobicity (CSH) and superoxide dismutase (SOD)) were obtained. The results showed that broken E. coli cells by ice growth were observed, but both oxides promoted E. coli survival under FT stress and prolonged bacterial survival time by 1.2–2.9 times, which were mainly attributed to the release of Fe³⁺ and Mn²⁺ caused by FT. The dissolutions of Fh and MnO₂ under FT, which took place at a low level in absence of E. coli cells, were markedly enhanced with bacterial interferences by 2–8 times and higher dissolved manganese concentrations were detected than iron. This was probably because that concentrated organic matters which were released from broken cells, rejected into unfrozen liquid layer and acted as electron donors and ligands to oxide dissolution. Compared with Fh system, more significant promotion of E. coli survival under FT in MnO₂ systems were found because of more SOD generations associated with high dissolved manganese concentrations and the stronger cellular protection by MnO₂ aggregations. The results suggested that FT significantly influenced the interactions between metal oxides and bacterial in water, resulting to changes in pathogen activity and metal element cycling.