Under intensive human activity, sewage discharge causes eutrophication-driven cyanobacteria blooms as well as nanomaterial pollution. In biological control of harmful cyanobacteria, top-down effect of protozoan has great potentials for removing cyanobacterial populations, degrading cyanotoxins, and improving phytoplankton community. ZnO nanoparticles as a kind of emerging contaminants have attracted increasing attention because of wide application and their high bio-toxicity effects on reducing the ingestion of aquatic animals including Paramecium, thereby possibly disturbing top-down control of cyanobacteria. Therefore, this study investigated the effects of ZnO nanoparticles at environmental-relevant concentrations on the protozoan Paramecium removing toxic Microcystis. Results showed Paramecium effectively eliminated all the Microcystis, despite exposure to ZnO nanoparticles. However, their ingestion rate was significantly reduced at more than 0.1 mg L⁻¹ ZnO nanoparticles, thereby delaying Microcystis removal. Nevertheless, at 0.1 mg L⁻¹ ZnO nanoparticles, the time to Microcystis extinction decreased compared to the group without ZnO nanoparticles, because Microcystis populations were reduced under this circumstance, while ingestion rate of Paramecium was unaffected. Furthermore, ZnO nanoparticles obviously accumulated in food vacuoles of Paramecium, and the size of nanoparticles aggregates and zinc concentrations in Paramecium were increased with ZnO nanoparticles concentrations. At the end of experiment, these food vacuoles were not dissipated. Overall, these findings suggest that ZnO nanoparticles impair protozoan top-down effects through reducing Microcystis and ingestion rate as well as disturbing functions of their digestive organelles, and highlight the need to consider the interfering effects of environmental pollutants on cyanobacterial removal efficiency by protozoans in natural waters.

Mangroves play a vital role in protecting the coastal community from the climate change effect and in the restoration of the coastal ecosystem. This research has been designed to determine the spatial and seasonal changes of potentially toxic elements’ (PTEs) concentration in sediments and their potential source contribution among the different human-driven processes in Sundarbans, Bangladesh. Different pollution evaluation indices, random forest (RF) model, conditional inference tree (CIT), self-organizing map (SOM), geographical information system (GIS), and principal component analysis (PCA) were used for the interpretation of sources and risk assessment of PTEs. The mean concentration of PTEs both in winter and monsoon seasons has fallen below the threshold effect level but exceeded the rare effect level of marine sediments quality standards. Results showed that the PTEs were significantly enriched (EF > 1.00 < 70.00) in sediments, whereas the Cd enrichment (7.00% samples) was very alarming (EF = 60–70). Except for Zn and Cd, other PTEs were enriched in 30–60% samples. The highest geoaccumulation and contamination factors for Cd were observed in 46–72% of samples. The ecological risk (ER) factors showed similar results where Cd showed strong to very strong factors (ER = 110–2218) in 80% of samples. The CIT explained the natural/geogenic and anthropogenic sources of pollution, where the higher CIT values for Cd indicated industrial, aquaculture, and coal-based thermal powerplant. The RF model provided that shrimp firms, power plants, industry, and seaport were recognized as the influential sources for Zn, Pb, Cr, Cd, and As in sediments. Though Pb and As were found as the most significant pollutants, Cd was identified as a severe threat to ecology and public health. Based on CIT, RF, SOM and PCA the order of PTEs in mangroves sediment were:industrial/urban > aquaculture/shrimpfirm > powerplant > seaportoperation > tourism > geogenic/natural. The present study will help the policymakers for effective and sustainable management of the mangrove ecosystem.

Numerous applications exist for graphene-based materials, such as graphene oxide (GO) nanosheets. Increased concentrations of GO nanosheets in the environment have the potential to have a large negative effect on the aquatic environment, with consequences for benthic organisms, such as polychaetes. The polychaete Hediste diversicolor mobilises the sediments, hence altering the availability of contaminants and the nutrients biogeochemical cycle. As such, this study proposes to assess the effects of different GO nanosheet concentrations on the behaviour, feeding activity, mucus production, regenerative capacity, antioxidant status, biochemical damage and metabolism of H. diversicolor. This study evidenced that H. diversicolor exposed to GO nanosheets had a significantly lower ability to regenerate their bodies, took longer to feed and burrow into the sediment and produced more mucus. Membrane oxidative damage (lipid peroxidation) increased in exposed specimens. The increased metabolic rate (ETS) evidenced a higher energy expenditure in exposed organisms (high use of ready energy sources – soluble sugars) to fight the toxicity induced by GO nanosheets, such as SOD activity. The increase in SOD activity was enough to reduce reactive oxygen species (ROS) induced by GO on cytosol at the lowest concentrations, avoiding the damage on proteins (lower PC levels), but not on membranes (LPO increase). This study revealed that the presence of GO nanosheets, even at the lower levels tested, impaired behavioural, physiological, and biochemical traits in polychaetes, suggesting that the increase of this engineered nanomaterial in the environment can disturb these benthic organisms, affecting the H. diversicolor population. Moreover, given the important role of this group of organisms in coastal and estuarine food webs, the biogeochemical cycle of nutrients, and sediment oxygenation, there is a real possibility for repercussions into the estuarine community.

Bensulfuron-methyl (BSM) residues in soil threaten the rotation of BSM-sensitive crops. Microbial biofilms formed on crop roots could improve the ability of microbes to survive and protect crop roots. However, the research on biofilms with the purpose of mitigating or even eliminating BSM damage to sensitive crops is very limited. In this study, one BSM-degrading bacterium, Hansschlegelia zhihuaiae S113, colonized maize roots by forming a biofilm. Root exudates were associated with increased BSM degradation efficiency with strain S113 in rhizosphere soil relative to bulk soil, so the interactions among BSM degradation, root exudates, and biofilms may provide a new approach for the BSM-contaminated soil bioremediation. Root exudates and their constituent organic acids, including fumaric acid, tartaric acid, and l-malic acid, enhanced biofilm formation with 13.0–22.2% increases, owing to the regulation of genes encoding proteins responsible for cell motility/chemotaxis (fla/che cluster) and materials metabolism, thus promoting S113 population increases. Additionally, root exudates were also able to induce exopolysaccharide production to promote mature biofilm formation. Complete BSM degradation and healthy maize growth were found in BSM-contaminated rhizosphere soil treated with wild strain S113, compared to that treated with loss-of-function mutants ΔcheA-S113 (89.3%, without biofilm formation ability) and ΔsulE-S113 (22.1%, without degradation ability) or sterile water (10.7%, control). Furthermore, the biofilm mediated by organic acids, such as l-malic acid, exhibited a more favorable effect on BSM degradation and maize growth. These results showed that root exudates and their components (such as organic acids) can induce the biosynthesis of the biofilm to promote BSM degradation, emphasizing the contribution of root biofilm in reducing BSM damage to maize.

Lead is a metal that exists naturally in the Earth's crust and is a ubiquitous environmental contaminant. The alleviation of lead toxicity is important to keep human health under lead exposure. Biosynthesized selenium nanoparticle (SeNPs) and selenium-enriched Lactobacillus rhamnosus SHA113 (Se-LRS) were developed in this study, and their potentials in alleviating lead-induced injury to the liver and intestinal tract were evaluated in mice by oral administration for 4 weeks. As results, oral intake of lead acetate (150 mg/kg body weight per day) caused more than 50 times and 100 times lead accumulation in blood and the liver, respectively. Liver function was seriously damaged by the lead exposure, which is indicated as the significantly increased lipid accumulation in the liver, enhanced markers of liver function injury in serum, and occurrence of oxidative stress in liver tissues. Serious injury in intestinal tract was also found under lead exposure, as shown by the decrease of intestinal microbiota diversity and occurrence of oxidative stress. Except the lead content in blood and the liver were lowered by 52% and 58%, respectively, oral administration of Se-LRS protected all the other lead-induced injury markers to the normal level. By the comparison with the effects of normal L. rhamnosus SHA113 and the SeNPs isolated from Se-LRS, high protective effects of Se-LRS can be explained as the extremely high efficiency to promote lead excretion via feces by forming insoluble mixture. These findings illustrate the developed selenium-enriched L. rhamnosus can efficiently protect the liver and intestinal tract from injury by lead.

The increased frequency and intensity of short-term extreme warming phenomena have been associated to harsh biological and ecosystem outcomes (i.e., mass mortalities in marine organisms). Marine heatwaves (MHWs), occurring when seasonal temperature threshold is exceeded for at least 5 consecutive days, may reduce the tolerance of coastal species toward additional pressures, but interactions between such multiple stressors are virtually unexplored. The present study aimed to characterize in Mytilus galloprovincialis the influence of a simulated MHW scenario on the toxicological effects of the pharmaceutical carbamazepine (CBZ), ubiquitously detected in the marine environment and chosen as model compound for this relevant class of emerging contaminants. The bioaccumulation of CBZ and responsiveness of various biological parameters, including immune system, antioxidant status, lipid metabolism and cellular integrity, were analyzed in exposed mussels both during and after the end of the heatwave. MHW appeared to strongly modulate accumulation of CBZ, paralleled by weakened immunocompetence and onset of oxidative disturbance that finally evolved to cellular damages and lipid metabolism disorders. Elaboration of the overall results through a quantitative Weight of Evidence model, revealed the highest hazard in organisms exposed to both the stressors 10 days after the end of the heatwave, suggesting that MHWs could leave a footprint on the capability of mussels to counteract CBZ toxicity, thus affecting their vulnerability and predisposition to adverse effects toward multiple stressors.

This study modified a passive sampling technique similar to the US EPA Method 325 A/B method but extended to include more toxic volatile organic compounds (VOCs) under varied climate conditions to enhance field applicability. A mixing chamber was built to determine uptake rates (Us) for the target compounds. It was found that the Us of 27 air toxics previously reported in the literature agreed reasonably well with our findings within 18%, thus proving the chamber's integrity. To broaden the compound coverage, both Carbopack X and Carboxen 569 were studied for a suite of toxic VOCs to meet stringent quality control (QC) criteria of correlation coefficients (R-square), method detection limits (MDL), back diffusion (BD), storage stability, as well as a wide range of climate conditions in temperature and humidity. After excluding the species that failed to pass any of the QC criteria, Carbopack X was found to fit 50 air toxics, whereas Carboxen 569 held 37. After excluding the overlapped species, 61 toxic VOCs can be determined with robust Us for a broad range of climate conditions when the two sorbents are used in pairs. A one-week field measurement was conducted to compare with the online thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) with hourly data resolution. The field passive sampling showed comparable results to the means of the online hourly measurements, despite the high variability of selected target compounds, such as toluene from 0.3 ppbv as the 5th percentile to the maximum of about 80 ppbv. Passive sampling clearly demonstrated the ability to smooth out concentration variability and thus the time-averaging strength of toxic VOCs, revealing its ideal role as an exposure monitor over time. The passive sampling method can be more desired than active sampling or online methods when the aim is simply the knowledge of prolonged time-averaged concentrations.

Benzene exposure can cause pancytopenia and immunosuppression, leading to serious diseases such as aplastic anemia (AA) or acute myeloid leukemia (AML), but the underlying mechanism has not been fully elucidated. Hypoxia-inducible factor 1 (HIF-1) is an important transcription factor that regulates many downstream target genes. In this study, we reported a novel mechanism by which high expression of HIF-1α alleviated benzene toxicity. Mice with high expression of HIF-1α (HIF-1α⁺) were obtained by the Tet-on system and doxycycline induction, and they and wild-type (WT) mice were exposed to 150 mg/kg benzene for 0, 1, 3, 7, 10, 14, and 28 days. Dynamic changes in hematopoietic and immune-related indicators and the role of HIF-1α were explored. The level of white blood cells in mice reached the highest level on the third day, and immunity was activated and then suppressed within 10 days. Significant pancytopenia and immunosuppression occurred at 14 days and were more pronounced at 28 days. The levels of HIF-1α, EPO, VEGF, RORγt, and IL-17 in WT mice gradually decreased with increasing benzene exposure days, while the levels of Foxp3 and IL-10 increased. These changes were alleviated in HIF-1α⁺ mice. High expression of HIF-1α increased the levels of EPO and VEGF, which helped to maintain the stability of the hematopoietic microenvironment. Simultaneously, it attenuated benzene-induced immunosuppression by alleviating the Th17/Treg imbalance. HIF-1α is expected to be a new target for benzene-induced diseases such as AA and AML.

The health risk induced by metal(loid)s in crops are becoming increasingly serious. In this study, eight major vegetables and rhizosphere soils were collected in a peri-urban area with intense electronic information manufacturing activities. The source, distribution and bioaccumulation of six typical metal(loid)s in different vegetable species were analyzed, and exposure risk through vegetable ingestion was estimated. Results showed that vegetables and agricultural soils in the study area suffered from serious metal(loid)s pollution, especially for Cd and Pb. The bioaccumulation capacity differed greatly among individual metal(loid)s and vegetable categories. In general, the highest transfer factors (TF) for Cd, Pb, and As were found in leafy vegetables, while leguminous vegetables had the highest TF of Cu and Zn and root vegetables had the highest TF for Cr. Significant correlations were found between concentrations in vegetables and rhizosphere soils for most metal(loid)s, the exceptions being Pb and Zn. The enrichment of Pb, Cd, Cr and As was mainly attributed to electronic information manufacturing activities, while the enrichment of Zn, Cu and Cd was associated with the application of commercial fertilizers and pesticides. The health risk associated with vegetable intake decreased in the order of leafy > fruit > leguminous > root vegetables. Leafy vegetables were identified as the category with the highest risk, with the mean risk value of 1.26. Cd was the major risk element for leafy vegetables. The non-carcinogenic risks estimated for leguminous and root vegetables were under the acceptable level. In conclusion, special attention should be paid to the health risks of toxic metal(loid)s in leafy vegetables in peri-urban areas with intense electronic information manufacturing activities. In order to minimize health risk, it is necessary to identify low-risk crops based on a comprehensive consideration of the metal(loid)s’ pollution characteristics, transfer factors and local people's consumption behaviors.

The health risks to populations induced by lead (Pb) and high-fat diets (HFD) have become a global public health problem. Pb and HFD often co-exist and are co-occurring risk factors for cognitive impairment. This study investigates effect of combined Pb and HFD on cognitive function, and explores the underlying mechanisms in terms of regulatory components of synaptic plasticity and insulin signaling pathway. We showed that the co-exposure of Pb and HFD further increased blood Pb levels, caused body weight loss and dyslipidemia. The results from Morris water maze (MWM) test and Nissl staining disclosed that Pb and HFD each contributed to cognitive deficits and neuronal damage and combined exposure enhanced this toxic injury. Pb and HFD decreased the levels of synapsin-1, GAP-43 and PSD-95 protein related to synaptic properties and SIRT1, NMDARs, phosphorylated CREB and BDNF related to synaptic plasticity regulatory, and these decreases was greater when combined exposure. Additionally, we revealed that Pb and HFD promoted IRS-1 phosphorylation and subsequently reduced downstream PI3K-Akt kinases phosphorylation in hippocampus and cortex of rats, and this process was aggravated when co-exposure. Collectively, our data suggested that combined exposure of Pb and HFD enhanced cognitive deficits, pointing to additive effects in rats than the individual stress effects related to multiple signaling pathways with CREB-BDNF signaling as the hub. This study emphasizes the need to evaluate the effects of mixed exposures on brain function in realistic environment and to better inform prevention of neurological disorders via modulating central pathway, such as CREB/BDNF signaling.