Occupational exposure to hexavalent chromium (Cr(VI)) can cause cytotoxicity and carcinogenicity. In this study, we established a liver injury model in rats via intraperitoneal injection of potassium dichromate (0, 2, 4, and 6 mg/kg body weight) for 35 d to investigate the mechanism of Cr(VI)-induced liver injury. We found that Cr(VI) induced hepatic histopathological lesions, oxidative stress, and apoptosis and reduced the expression of mitochondrial-related regulatory factors such as adenosine 5′-monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) in a dose-dependent manner. Furthermore, Cr(VI) promoted mitochondrial division and inhibited fusion, leading to increased expression of caspase-3 and production of mitochondrial reactive oxygen species. Our study demonstrates that long-term exposure to Cr(VI) induces mitochondrial dynamics disorder by inhibiting AMPK/PGC-1α signaling pathway in rat liver.

Due to the abusive usage of antibiotics in animal husbandry, a large amount of residual antibiotics has been released into the environment, therein posing great threat against both environment security and public health. Therefore, it is of great significance to investigate the toxicity of antibiotics on the widely-applied bioindicator-earthworm. In this work, the physiological parameters and the intestinal bacteria community of Metaphire guillelmi were monitored simultaneously to evaluate their sensitivity to the tetracycline (TC) exposure. As expected, the antioxidant enzyme activity and coelomocyte apoptosis acted fairly well as biomarkers for the TC toxicity. In contrast, the intestinal bacteria of Metaphire guillelmi responded varyingly to different TC doses. When TC concentration increased from 0 to 35.7 μg cm⁻², the percentage of the Proteobacteria phylum declined significantly from 85.5% to 34.4%, while the proportions of the Firmicutes, Planctomycetes and Atinomycete phyla clearly increased (p < 0.05). Meanwhile, the levels of TC resistance genes tetA, tetC, and tetW increased with the increasing TC concentration, in contrast to the declined abundance in denitrifying genes nirS and nosZ (p < 0.05). By analyzing the correlation between the antioxidant enzyme activity and the dominant intestinal bacteria in the worm gut, it is interesting to found that the four dominant bacteria genera Mesorhizobium, Aliihoeflea, Romboutsia, and Nitrospira are the promising bioindicator of TC stress due to their sensitive response. This work shed novel light on evaluating the ecotoxicological risks posed by residual TC in environment by using a combination of physiological parameters and intestinal bacterial activity in earthworms.

Di-(2-ethylhexyl) phthalate (DEHP), a plasticizer that is mainly used in the production of polyvinyl alcohol-containing chloride products, has attracted attention due to potential threats to human health and the environment. Nevertheless, knowledge of DEHP-induced nephrotoxicity is still limited. To explore the mechanism of DEHP-induced nephrotoxicity, quail were treated with 0, 250, 500 and 1000 mg/kg DEHP by oral gavage for 45 days. Based on the results of histopathological analysis, DEHP exposure induced a disorganized renal structure, a partially dilated glomerulus and an atrophied Bowman’s space. Renal tubular epithelial cells were unclear, and swelling of columnar epithelial cells was observed, suggesting that DEHP exposure caused renal disease and renal injury. Notably, DEHP interfered with the homeostasis of cytochrome P450 systems (CYP450s) by increasing the activities or contents of CYP450s (total CYP450, Cyt b5, ERND, APND, AH and NCR). The expression levels of certain CYP450 isoforms (CYP1A, CYP1B, CYP2C, CYP2D, CYP2J and CYP3A) were significantly downregulated in the kidney in DEHP-treated quail. Furthermore, DEHP induced the expression of nuclear receptors (AHR, CAR and PXR) in a dose-dependent manner. The results of this study suggested that DEHP-induced nephrotoxicity in quail was associated with the induction of nuclear xenobiotic receptor (NXR) responses and interference with CYP450 homeostasis. In conclusion, all data indicated that DEHP induced nephrotoxicity by triggering NXRs and modulating the cytochrome P450 system. The results of this study provide a new basis for understanding the nephrotoxicity of DEHP.

Antibiotic resistance genes (ARGs) and mobile gene elements (MGEs), the emerging genetic contaminants, are regarded as severe risks to public health for impairing the inactivation efficacy of antibiotics. Secondary effluents from wastewater treatment plants are the hotspots for spreading these menaces. Herein, sulfidated nanoscale zero-valent iron (S-nZVI) was occupied to remove ARGs and MGEs in secondary effluents and weaken the regrowth capacity of their bacterial carriers. The effects of S/Fe molar ratios (S/Fe), initial pH and dosages on 16S rRNA and ARGs removal were also investigated. Characterization, mass balance and scavenging experiments were conducted to explore the mechanisms of the gene removal. Quantitative PCR (qPCR) and high throughput fluorescence qPCR showed more than 3 log unit of 16S rRNA and seven out of 10 ARGs existed in secondary effluent could be removed after S-nZVI treatment. The mechanisms might be that DNA accepted the electron provided by the Fe⁰ core of S-nZVI after being adsorbed onto S-nZVI surface, causing the decrease of 16S rRNA, ARGs and lost their regrowth capacity, especially for typical MGE (intI1) and further inhibiting the vertical gene transfer (VGT) and intI1-induced horizontal gene transfer (HGT). Fe⁰ core was oxidized to iron oxides and hydroxides at the same time. High throughput sequencing, network analysis and variation partitioning analysis revealed the complex correlations between bacteria and ARGs in secondary effluent, S/Fe could directly influence ARGs variations, and bacterial genera made the greatest contribution to ARGs variations, followed by MGEs and operational parameters. As a result, S-nZVI could be an available reductive approach to deal with bacteria and ARGs.

The accumulation of cadmium (Cd) in rice grains is closely associated with the content of mineral nutrients and amino acid metabolism, but the causal link among them is unclear. Profiles of amino acids (AAs) and quantities of essential nutrients in grains from early and late rice cultivars grown at four sites with different Cd levels were analyzed in the present study. Hazard quotients (HQs) for consumers by intake of rice from late cultivars were much higher than that from early cultivars at sites with soil Cd content of 0.25, 0.61 and 0.84 mg kg⁻¹. Cadmium accumulation in grains resulted in a sharp reduction of total essential AAs and non-essential AAs in both early and late rice cultivars. High-Cd-accumulating (HCA) cultivars had significantly higher level of glutamate (Glu) than low-Cd-accumulating (LCA) cultivars when rice Cd content was less than 0.20 mg kg⁻¹. However, Glu level in grains dramatically declined with the accumulation of Cd, which subsequently leaded to the reduction of other AAs. Cadmium content was well predicted by five amino acids (i.e., Glu, Alanine, Phenylalanine, Glycine and Threonine) or four essential elements (Ca, Fe, Mn and Zn) when rice Cd was less than 0.80 mg kg⁻¹. Amino acids played more important roles than nutrients in Cd accumulation. When Cd content was in the range of 0.40–1.16 mg kg⁻¹, the Mn content in rice increased significantly with the increase of Cd content, while the Glu content dropped down synchronously. Remarkably, the ratio between Mn and Glu displayed the highest direct path coefficient on Cd accumulation than any single cation or amino acid. These results indicate that high capacity in synthesizing Glu and concentrating Mn is the determinant factor for Cd accumulation in rice grains, and abundant Glu in aleurone layer may alleviate Cd toxicity by forming Glu-Cd complex.

Plastic marine debris hyper-concentrates hydrophobic contaminants such as polycyclic aromatic hydrocarbons (PAHs) and can transfer these sorbed contaminants to biota following ingestion. PAHs are known to induce cardiotoxicity and visual toxicity at sublethal doses. Juvenile White seabass (Atractoscion nobilis) fish were fed environmentally relevant concentrations of either virgin polystyrene or benzo(a)pyrene (BaP)-sorbed polystyrene for 5 days and were monitored for changes in phototactic response, swimming behavior, and hepatic cytochrome p450 1A (CYP1A) enzyme activity. No significant differences in the monitored endpoints were recorded in fish that ingested either polystyrene or BaP-sorbed polystyrene relative to control fish following the short-term exposure. However, fish exposed to 252 μg/L BaP alone as a positive control had significantly elevated CYP1A enzyme activity (p = 0.046) and impaired phototactic response (p = 0.020), though no altered swimming behavior was observed (p = 0.843) relative to control fish. These results demonstrate that pelagic fish ingesting environmentally relevant concentrations of BaP-sorbed polystyrene for a short, 5-day duration do not demonstrate measurable changes in vision, swimming activity, nor CYP1A activity. High variability within enzyme activity and behavioral responses suggest that lack of significant effects may be due to low sample size.

Pine needles are employed as alternative biomonitoring agents in atmospheric studies. In this study, pine (Pinus Pinea) components (needles and branches) and air samples were collected simultaneously to monitor polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) from Gemlik, Turkey between January and December 2016. The relationship between ambient air and pine needles were examined to enlighten the usability of pine components as passive samplers for persistent organic pollutants (POPs) in the Marmara region. Average ∑14PAH concentrations for the ambient air, pine needles, and pine branches were 23.1 ± 18.3 ng/m3, 626 ± 306 ng/g DW and 548 ± 261 ng/g DW respectively. PCB concentrations were 118 ± 74 pg/m3, 7.5 ± 2.1 ng/g DW and 6.8 ± 2.9 ng/g DW and ∑10 OCP concentrations were 122 ± 89 ng/m3,1.3 ± 1.5 ng/g DW and 10.0 ± 3.8 ng/g DW in the same order. Levels of PAHs and PCBs were higher in needles than branches. PAH, PCB and OCP concentrations in pine components tended to decrease with increasing temperatures in spring. PAH compounds with medium and light molecular weighted ones were found to be dominant. On the other hand, the predominant PCB components were the medium-weighted congeners while γ-HCH, Heptachlor endo. Epox. Iso A, endrin aldehyde, and methoxychlor were the dominant OCP species.

Anthropogenic activities have significantly changed the stoichiometry and concentrations of nutrients in coastal waters. Silicon (Si) has become a potential limiting nutrient due to disproportionate nitrogen, phosphorus, and silicate inputs into these areas. The disrupted nutrient ratios can cause changes to metal sensitivity and accumulation in marine diatoms, an important group of eukaryotic phytoplankton that requires silicon for growth. In this study, we examined the effects of Si availability on the metal sensitivity in the diatom P. tricornutum. We found that Si starvation dramatically compromised its cadmium, copper, and lead tolerances. Interestingly, multiple lines of evidence indicated that Si-enriched cells had higher metal adsorption and influx rates than Si-starved cells. Yet Si-enriched cells also had a greater ability to respond to and counteract metal toxicity via elevated expression of membrane and vacuolar metal transporters and greater antioxidant activities which scavenge reactive oxygen species created by metal stress.

Numerous studies have sought to address the extraction of metals from printed circuit boards by employing bioleaching process. However, separation and recovery of the bioleached metals have always been a bottleneck. Herein, we demonstrate effective recovery of bioleached Au and Cu via selective separation using ion exchange resins. pH-edge experiments revealed high affinity of Amberjet™ 4200 resin towards Au (adsorption capacity > 98%) over the entire pH range from pH 2–10, whereas Amberlite IRC-86 resin recorded very high Cu adsorption at around pH 5. Therefore, a two-step sequential process was designed for the effective separation and recovery of Au and Cu. In the 1st step, Au was completely recovered by using the Amberjet™ 4200 at the natural pH of 7.5. Subsequently, the Au-free solution was adjusted to pH 5 and Cu was recovered by using Amberlite IRC-86 (2nd step). Consequently, 98.7% Au and 78.9% Cu were successfully recovered. Therefore, this study provides a technical guideline for the selective recovery of Au and Cu from bioleached wastewater, which promotes effective waste minimization and efficient resource recovery.

The residual characteristics and the adsorption-desorption behaviors of azoxystrobin (AZO) as well as the soil ecological effects in the individual repeated treatments of AZO and its combination with chlorothalonil (CTL), chlortetracycline (CTC) and ciprofloxacin (CIP) were systematically studied in organic manure (OM)-amended soil under laboratory conditions. The presence of CTL, CTC, and CIP, both individually and combined, decreased the sorption affinity of AZO with the Freundlich adsorption and desorption coefficient decreasing by 0.3–24.2%, and CTC and CIP exhibited greater adverse effects than CTL. AZO dissipated slowly and the residues significantly accumulated during ten repeated treatments. The dissipation of AZO was inhibited to different degrees in the combined treatments. Biolog analysis revealed that the soil microbial functional diversity in the OM-soil + AZO and OM-soil + AZO + CTL treatments was higher than that in the OM-soil treatment during the former three repeated treatments, but which was inhibited during the latter seven repeated treatments. The soil microbial functional diversity in the OM-soil + AZO + CTC, OM-soil + AZO + CIP and OM-soil + AZO + CTL + CTC + CIP treatments was inhibited during the ten repeated treatments compared with OM-soil treatment. Metagenomic results showed that all repeated treatments significantly increased the relative abundance of Actinobacteria, but significantly decreased that of Proteobacteria and Firmicutes during the ten repeated treatments. Furthermore, the relative abundance of soil dominant bacterial genera Rhodococcus, Mycobacterium and Arthrobacter in all the repeated treatments significantly increased by 1.5–1283.9% compared with the OM-soil treatment. It is concluded that coexistence of CTL, CTC and CIP, both individually and combined, with AZO can inhibit the dissipation of AZO, reduce the adsorption affinity of AZO on soil, and alter the soil microbial community structure and functional diversity.