Plant-derived materials as environmentally friendly biosorbents to remove heavy metals from wastewater have been extensively studied. However, the chemical oxygen demand (COD) increase caused by the plant-derived biosorbent has not been considered previously. In this study, water hyacinth was used as biosorbent to remove Cd(II) from wastewater. About 66% of Cd(II) was removed by the biosorbent with a maximum biosorption capacity (qₘₐₓ) of 21.6 mg g⁻¹. However, the COD of the filtrate increased from 0 to 292 mg L⁻¹ during this process. Subsequently, endophytes, microalgae and the microalgae-endophyte symbiotic system (MESS) were assessed for the simultaneous Cd(II) and COD removal. Among these three systems, the MESS achieved the best performance. After 3 d of inoculation, the extent of total Cd(II) removal increased to 99.2% while COD decreased to 77 mg L⁻¹. This study provides a new insight into the application of a plant-derived biosorbent in combination with microalgae and endophytes for the effective treatment of heavy metal-bearing wastewater.

Due to the potential toxicity of polycyclic aromatic hydrocarbons (PAHs) to humans, the uptake and translocation of PAHs in food crops have gained much attention. However, it is still unclear whether phloem participates in the acropetal translocation of PAHs in plants. Herein, the evidence for acropetal translocation of phenanthrene (a model PAH) via phloem is firstly tested. Wheat (Triticum aestivum L.) new leaves contain significantly higher phenanthrene concentration than old leaves (P < 0.05), and the inhibitory effect on phenanthrene translocation is stronger in old leaves after abscisic acid and polyvinyl alcohol (two common transpiration inhibitors) application. Phenanthrene concentration in xylem sap is slightly higher than in phloem sap. Ring-girdling treatment can significantly reduce phenanthrene concentration in castor bean (Ricinus communis L.) leaves. Two-photon fluorescence microscope images indicate a xylem-to-phloem and acropetal phloem translocation of phenanthrene in castor bean stem. Therefore, phloem is involved in the acropetal translocation of phenanthrene in wheat seedlings, especially when the xylem is not mature enough in scattered vascular bundle plants. Our results provide a deeper understanding of PAH translocation in plants, which have significant implications for food safety and phytoremediation enhancement of PAH-contaminated soil and water.

Elasmobranchs are particularly prone to accumulating contaminants due to their life history patterns and relatively high trophic position. However, several compounds, especially contaminants of emerging concern, have still not been well studied in this group. Here, we aimed to determine the occurrence and concentrations of several inorganic and organic contaminants in different tissues of the Brazilian guitarfish Pseudobatos horkelii. This species is a critically endangered species, endemic from the Southwest Atlantic which uses southern Brazilian waters as a nursery habitat. Polycyclic aromatic hydrocarbons (PAHs), emerging pesticides, pharmaceutical and personal care products (PPCPs) and trace metals were determined in five biological tissues in order to assess the accumulation and organotropism of these compounds. Except for chlorothalonil and triclosan, all compounds were detected in, at least, one tissue, mostly in liver samples. All compounds differed among tissues, with liver presenting the higher concentrations of several contaminants, followed by muscle and gills. PAHs and PPCPs were the most detected analytes and presented the highest concentrations among tissues. Diclofenac levels were determined, for the first time in elasmobranchs, and were relatively high, when compared to other fishes. Finally, relatively high concentrations of PAHs, dichlofluanid and octocrylene in muscle might be suggestive of chronic exposure, presenting also human health implications. Regarding trace metals, contrary to most elasmobranch studies, Hg levels were low in all tissues, whereas Cd and Pb here higher in liver, and gills and blood samples, respectively. Our results indicate that P. horkelii is exposed to several organic and inorganic which might affect this species in a long-term scale. Concerning the determination of emerging contaminants, it is likely that other elasmobranchs are also exposed to these compounds and special attention should be given to this issue in order to predict future effects on this group.

Owing to environmental health concerns, a number of per- and polyfluoroalkyl substances (PFAS) have been phased-out, and increasingly replaced by various chemical analogs. Most prominent among these replacements are numerous perfluoroether carboxylic acids (PFECA). Toxicity, and environmental health concerns associated with these next-generation PFAS, however, remains largely unstudied. The zebrafish embryo was employed, in the present study, as a toxicological model system to investigate toxicity of a representative sample of PFECA, alongside perfluorooctanoic acid (PFOA) as one of the most widely used, and best studied, of the “legacy” PFAS. In addition, high-resolution magic angle spin (HRMAS) NMR was utilized for metabolic profiling of intact zebrafish embryos in order to characterize metabolic pathways associated with toxicity of PFAS. Acute embryotoxicity (i.e., lethality), along with impaired development, and variable effects on locomotory behavior, were observed for all PFAS in the zebrafish model. Median lethal concentration (LC₅₀) was significantly correlated with alkyl chain-length, and toxic concentrations were quantitatively similar to those reported previously for PFAS. Metabolic profiling of zebrafish embryos exposed to selected PFAS, specifically including PFOA and two representative PFECA (i.e., GenX and PFO3TDA), enabled elaboration of an integrated model of the metabolic pathways associated with toxicity of these representative PFAS. Alterations of metabolic profiles suggested targeting of hepatocytes (i.e., hepatotoxicity), as well as apparent modulation of neural metabolites, and moreover, were consistent with a previously proposed role of mitochondrial disruption and peroxisome proliferator-activated receptor (PPAR) activation as reflected by dysfunctions of carbohydrate, lipid and amino acid metabolism, and consistent with a previously proposed contribution of PFAS to metabolic syndrome. Taken together, it was generally concluded that toxicity of PFECA is quantitatively and qualitatively similar to PFOA, and these analogs, likewise, represent potential concerns as environmental toxicants.

Plutonium in the environment has drawn significant attentions due to its radiotoxicity in high concentration and source term linked with nuclear accidents and contaminations. The isotopic ratio of plutonium is source dependent and can be used as a fingerprint to discriminate the sources of radioactive contaminant. ²³⁹Pu, ²⁴⁰Pu and ¹³⁷Cs in surface soil and soil cores collected from Northern Xinjiang were determined in this work. The concentrations of ²³⁹,²⁴⁰Pu and ¹³⁷Cs are in the range of 0.06–1.20 Bq kg⁻¹, and <1.0–31.4 Bq kg⁻¹ (decay corrected to Sep. 2017), respectively, falling in the ranges of global fallout in this latitude zone. The ²⁴⁰Pu/²³⁹Pu atomic ratios of 0.118–0.209 and ²³⁹,²⁴⁰Pu/¹³⁷Cs activity ratios of 0.039–0.215 were measured. Among the investigated sites, distinctly lower ²⁴⁰Pu/²³⁹Pu atomic ratios of 0.118–0.133 and higher ²³⁹,²⁴⁰Pu/¹³⁷Cs activity ratios of 0.065–0.215 compared to the global fallout values were observed in the northwest part, indicating a significant contribution from other source besides the global fallout. This extra source is mainly attributed to the releases of atmospheric nuclear weapons testing at Semipalatinsk Nuclear Test Site, which was transported by the west and northwest wind through the river valley among mountains in this region. This contribution is estimated to account for 28–43% of the global fallout in the northwest part of Northern Xinjiang. The contribution from the Chinese atmospheric nuclear weapons testing to this region is negligible due to the lack of appropriate wind direction to transport the radioactive releases to this region.

Studies have showed that some of the most common male reproductive disorders present in adult life might have a fetal origin. Perfluorooctane sulfonic (PFOS) is one of the major environmental pollutants that may affect the development of male reproductive system if exposed during fetal or pubertal periods. However, whether PFOS exposure during fetal period affects testicular functions in the adult is still unclear. Herein, we investigated the effects of a brief gestational exposure to PFOS on the development of adult Leydig- and Sertoli-cells in the male offspring. Eighteen pregnant Sprague-Dawley rats were randomly divided into three groups and each received 0, 1 or 5 mg/kg/day PFOS from gestational day 5–20. The testicular functions of F1 males were evaluated on day 1, 35 and 90 after birth. PFOS treatment significantly decreased serum testosterone levels of animals by all three ages examined. The expression level of multiple mRNAs and proteins of Leydig (Scarb1, Cyp11a1, Cyp17a1 and Hsd17b3) and Sertoli (Dhh and Sox9) cells were also down-regulated by day 1 and 90. PFOS exposure might also inhibit Leydig cell proliferation since the number of PCNA-positive Leydig cells were significantly reduced by postnatal day 35. Accompanied by changes in Leydig cell proliferation and differentiation, PFOS also significantly reduced phosphorylation of glycogen synthase kinase-3β while increased phosphorylation of β-catenin. In conclusion, gestational PFOS exposure may have significant long-term effects on adult testicular functions of the F1 offspring. Changes in Wnt signaling may play a role in the process.

Polybrominated biphenyl ethers (PBDEs) are commonly added to electronic products for flame-retardation effects, and are attracting more and more attentions due to their potential toxicity, durability and bioaccumulation. This study conducts a sysmtematic review to understand the human exposure to PBDEs from e-waste recycling, especially exploring the exposure pathways and human burden of PBDEs as well as investigating the temporal trend of PBDEs exposure worldwide. The results show that the particular foods (contaminated fish, poultry, meat and breast milk) ingestion, indoor dust ingestion and indoor air inhalation may be key factors leading to human health risks of PBDEs exposure in e-waste recycling regions. Residents and some vulnerable groups (occupational workers and children) in e-waste recycling areas may face higher exposure levels and health risks. PBDE exposure is closely related to exposure level, exposure duration, e-waste recycling methods, and dietary customs. High levels of PBDEs are found in human tissues (breast milk, hair, blood (serum), placenta and other tissues) in e-waste areas, at far higher levels than in other areas. Existing data indicate that PBDE exposure levels do not present any apparent downward trend, and will possibly cause serious human diseases. More epidemiological studies are still needed to provide a solid basis for health risk assessment.

This study reports a characterization of indoor polycyclic aromatic hydrocarbons (PAHs) associated with dust (dust-PAHs) in household evaporative coolers and their associated health effects. Extensive analysis showed that the indoor dust-PAHs stemmed mostly from pyrogenic sources (vehicular emissions) with mean total concentrations limited between 131 and 429 ng g−1. The distribution pattern of PAHs based on number of rings exhibited the following order of decreasing relative abundance: 4 > 3 > 5 > 6 > 2 rings. Results indicate that the mutagenicity of dust-PAHs exceeded their carcinogenicity, but that the potential carcinogenic effects are still significant. The mean lifetime cancer risk for different age groups for three pathways based on Model 2 (dermal (1.39 × 10−1 to 1.91 × 10−2), ingestion (2.13 × 10−3 to 8.08 × 10−3) and inhalation (1.62 × 10−7 to 4.06 × 10−7)) was 7.4–146 times higher than values predicted by Model 1 (dermal (5.13 × 10−5 to 3.03 × 10−3), ingestion (9.34 × 10−5 to 1.31 × 10−3) and inhalation (7.13 × 10−20 to 1.68 × 10−20)). Hence, exposure to dust-PAHs in household evaporative coolers lead to high risk, especially for children (less than 11 years) (HQ = 2.71 × 10−20 to 54.8 and LTCRs = 7.13 × 10−20 to 1.39 × 10−1). Strategies should be considered to eliminate such pollutants to protect people, especially children, from the non-carcinogenic and carcinogenic effects by changing household evaporative coolers with other cooling systems.

Two typical polycyclic musks (PCMs), namely 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN), were determined in 63 surface water and 42 sediment samples collected from the North Canal River watershed, an urban catchment located in the megacity Beijing, China. Concentrations of HHCB and AHTN were 13.2 ng/L–395 ng/L and 2.98 ng/L–232 ng/L in surface water, while 4.10 ng/g–818 ng/g and 1.21 ng/g–731 ng/g in sediments. The results showed that PCM concentrations in the North Canal River watershed were at the high end when compared to that in other regions in China and worldwide. A watershed-wide annual mass budget showed that HHCB (∼150 kg/year) and AHTN (∼80 kg/year) mainly originated from urban wastewaters. Both PCMs were eliminated primarily by outflowing water (72 kg/year and 43 kg/year for HHCB and AHTN, respectively) and due to losses to the atmosphere (40 kg/year and 26 kg/year for HHCB and AHTN, respectively). An assessment of ecological risks posed by HHCB and AHTN to aquatic organisms in the North Canal River watershed was performed by using a tiered ecological risk assessment. The results showed that PCMs were unlikely to pose an ecological risk at the watershed scale (the probability of the incidence of adverse effect was <3.5% at the 99% protection level). However, according to the results from the risk quotient method, the tributaries draining wastewater effluents should be hotspots that warrant further research in future.