The dissemination of antibiotic resistance (AR) has attracted global attention because of the increasing antibiotic treatment failure it has caused. Through natural transformation, a live bacterium takes up extracellular DNA (exDNA), which facilitates AR dissemination. However, recovery of exDNA from water samples is challenging. In this study, we validated a consecutive ultrafiltration-based protocol to simultaneously recover intracellular DNA (inDNA), dissolved exDNA (Dis_exDNA, dissolved in the bulk water), and adsorbed exDNA (Ads_exDNA, adsorbed to the surfaces of suspended particles). Using hollow fiber ultrafiltration (HFUF), all DNA fractions were concentrated from environmental water samples, after which Dis_exDNA (supernatant) was separated from inDNA and Ads_exDNA (pellets) using centrifugation. Ads_exDNA was washed off from the pellets with proteinase K and sodium phosphate buffer. Dis_exDNA and Ads_exDNA were further concentrated using centrifugal ultrafiltration, from which silica binding was performed. inDNA was extracted from washed pellets with a commercial kit. For inDNA, HFUF showed recovery efficiencies of 96.5 ± 18.5% and 88.0 ± 2.0% for total cells and cultured Escherichia coli, respectively (n = 3). To represent all possible DNA fragments in water environment, exDNA with different lengths (10.0, 4.0, 1.0, and 0.5 kbp) were spiked to test the recovery efficiencies for Dis_exDNA. The whole process achieved 62.2%–62.9% recovery for 10 and 4 kbp exDNA, and 38.8%–44.5% recovery for 1.0 and 0.5 kbp exDNA. Proteinase K treatment enhanced the recovery of Ads_exDNA by 4.0–10.7 times. The protocol was applied to water samples from an urban river in Tokyo, Japan. The abundance of AR genes (ARGs) in inDNA, Dis_exDNA, and Ads_exDNA increased downstream of wastewater treatment plants. ARGs in Ads_exDNA and Dis_exDNA accounted for 1.8%–26.7% and 0.03%–20.9%, respectively, of the total DNA, implying that Ads_exDNA and Dis_exDNA are nonnegligible potential pools for the horizontal transfer of ARGs.

The present work reported a high-throughput strategy for the analysis of 21 perfluorinated compounds (PFCs) in drinking water, tap water, river water and plant effluent from southern China by supramolecular solvent (SUPARS) vortex-mixed microextraction combined with high performance liquid chromatography-Orbitrap high resolution mass spectrometry (HPLC-Orbitrap HRMS). The SUPRAS without heating assistance is less solvent-consumption, meeting the requirements for green environmental protection and sustainable development. Parameters in the microextraction such as volume of dodecanol and tetrahydrofuran (THF), vortexing extraction and centrifugation time, salt concentration were investigated. The optimal extraction conditions were 250 μL of undecanol, 1.0 mL of THF and 20.0% (w/v, 4 g) NaCl. Under the optimum conditions, method limit of detection and method limit of quantitation in the ranges of 0.01–0.08 μg/L and 0.03–0.25 μg/L, good recoveries (72.5–117.8%) and intra-day precision (1.1–11.2%, n = 6), high enrichment factors (48–78) were obtained. The developed method was successfully applied for analysis of PFCs in 13 drinking water, tap water, river water and plant effluent samples collected from southern China. Perfluorobutane sulfonic acid was detected in one river water with concentration of 0.48 μg/L and 1H,1H,2H,2H-Perfluorooctane sulfonic acid was detected in one river water and two plant effluent samples with concentrations in the range of 0.14–0.67 μg/L.

As observed among residents in electronic waste (e-waste) recycling areas, dioxins can disrupt the homeostasis of endocrine hormones and the balance of thyroid hormones. Few studies, however, have examined whether e-waste recycling activities influence steroid hormone equilibrium in the general adult male population. This study evaluated the association between steroid hormones and the physical burdens of dioxins in the general adult male population residing in an e-waste region. In September 2017, 74 adult males residing in an e-waste dismantling region were enrolled in the current study. Approximately 10 mL of blood was collected from each adult male, and the serum samples were separated through centrifugation. Then, the levels of dioxin and steroid hormones in the serum of the participants were measured. We treated dioxin levels as categorical variables in the general linear model according to quartiles (25, 50, and 75 percentile). Comparing the findings with a reference group (< 25th percentile), we noted significantly higher dehydroepiandrosterone (DHEA) level in men with low serum polychlorinated dibenzofuran-toxic equivalent (PCDFs-TEQ) level between 3.80 and 6.31 pg/g lipid (1933 vs. 1447 pg/ml) and low polychlorinated dibenzo-p-dioxins and dibenzofurans-TEQ (PCDD/PCDFs-TEQ) between 8.57 and 15.11 pg/g lipid (1996 vs. 1360 pg/ml). Moreover, a significantly higher androstenedione (A-dione) level was found in men whose serum PCDFs-TEQ ≥ 11.34 pg/g lipd (2404 vs. 1848). What’s more, there were significantly higher 3β-hydroxysteroid dehydrogenase (3β-HSD) concentrations in low- and high-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) groups (1.30–1.67 and ≥ 2.64 pg-TEQ/g lipid, respectively with 719 and 807 vs. 496, respectively). Our findings suggest that specific dioxin exposure may disturb normal DHEA, A-dione levels, and enzyme activity in the general adult male population in an e-waste region of China.

A method for the preconcentration of mercury using vortex-assisted temperature-controlled dispersive liquid-phase microextraction (VA-TC-DLPME) is proposed. A miniaturized gas-liquid separator (m-GLS) was developed and applied to the determination of mercury after VA-TC-DLPME. The detection was performed using cold vapor atomic absorption spectrometry (CV AAS). Ammonium pyrrolidine dithiocarbamate (APDC) reagent was used as a complexing agent for Hg(II). The VA-TC-DLPME method consists in dispersing the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF₆]) in the aqueous phase by vigorous vortexing, followed by heating and cooling in an ice bath. The mixture was submitted to centrifugation, and the sedimented rich phase was then dissolved in an acid solution to reduce viscosity. Mercury was quantified in the final solution using m-GLS and CV AAS. Under optimized conditions, the method presents a limit of detection of 4.5 × 10⁻² μg L⁻¹, and an enrichment factor of 54. The accuracy was evaluated by the determination of mercury in reference material-certified ERM-CE 278, mussel tissue. The method was applied to the determination of mercury in fish oil samples. The developed m-GLS can be tested for use after other LPME procedures.

In our research, thiolated reduced graphene oxide aerogels (TrGOAs) was successfully prepared by using graphene oxide (GO) as precursor and sodium hydrosulfide (NaSH) as reductant via a one-pot one-step hydrothermal route under normal pressure and a subsequent freeze-drying, used as a novel carbon-based adsorptive material for adsorbing Cu(II) ions from deionized water. These aerogels show excellent adsorption ability towards Cu(II) ions, which have a huge adsorption amount around 421.21 mg·g⁻¹. We studied the mechanism of the adsorption process of TrGOA-5, and the results found that the pseudo-second-order kinetic model and the Freundlich isotherm model were able to describe this process well. We also explored the interference of pH values in copper ion solutions during this adsorption process, suggesting that increasing pH is good for obtaining a higher adsorption capacity. In addition, solid-liquid separation can be readily realized by filtration and centrifugation after the end of the adsorption experiment. Overall, this research offers a relatively simple and cut-price strategy to obtain thiolated reduced graphene oxide aerogels, and these novel graphene-based adsorbents have a superior adsorption ability and recyclability in segregating copper ions from polluted water.

Treatments using ozone for filter backwash water (FBW) and calcium oxide for floated residue (FR) were evaluated adopting bench-scale testing for the inactivation of Giardia spp. cysts and Cryptosporidium parvum oocysts. The protocol chosen for protozoa detection involved following the concentration step by direct centrifugation (adding ICN 7X cleaning solution at 1.0%) and purification by immunomagnetic separation (IMS). The FR treatment with calcium oxide (dosage of 23 mg CaO 100 mL⁻¹ and 3-day contact time at 25 °C) proved to be efficient, as no parasites were detected after the treatment. The reduction of calcium oxide dosage (16 mg CaO 100 mL⁻¹ and 3-day contact time at 25 °C) was insufficient to inactivate the protozoa, since potentially viable organisms were identified using propidium iodide (PI). Concerning the disinfection conditions with ozone (5-min and 10-min contact time and dosage of 10 mg O₃ L⁻¹ and 7.5 mg O₃ L⁻¹, respectively), there was complete removal of the target organisms, as no protozoa were detected after the FBW treatment. From the results obtained, the tested treatments can be considered promising alternatives for water treatment plants (WTPs). However, the costs incurred from these treatments have to be considered.

This study investigated for the first time the effects of ZnO nanoparticle (NP) chronic exposure (28 days) on Tigriopus fulvus. Acute toxicity (48 h) of three Zn chemical forms was assessed as well including the following: (a) ZnO nanoparticles (NPs), (b) Zn²⁺ from ZnO NP suspension after centrifugation (supernatant) and (c) ZnSO₄ H₂O. Physical-chemical and electronic microscopies were used to characterize spiked exposure media. Results showed that the dissolution of ZnO NPs was significant, with a complete dissolution at lowest test concentrations, but nano- and micro-aggregates were always present. Acute test evidenced a significant higher toxicity of Zn²⁺ and ZnSO₄ compared to ZnO NPs. The chronic exposure to ZnO NPs caused negative effects on the reproductive traits, i.e. brood duration, brood size and brood number at much lower concentrations (≥ 100 μg/L). The appearance of ovigerous females was delayed at higher concentrations of ZnO NPs, while the time required for offspring release and the percentage of non-viable eggs per female were significantly increased. ZnO NP subchronic exposure evidenced its ability to reduce T. fulvus individual reproductive fitness, suggesting that ZnO NPs use and release must be carefully monitored. Graphical abstract Graphical Abstract.

A passive sampling method based on diffusive gradients in thin films (DGT) using ceria oxide (CeO₂) binding gel was developed for in situ measurement of dissolved reactive phosphorus (DRP). CeO₂-based DGT showed excellent uptake performance for DRP, and the uptake mass was consistent with the predication by DGT equation. pH (4.2~9.4) and ionic strength (0.01~500 mM) had no effects on the uptake of DRP. Filed deployment of CeO₂-DGT in reservoir water and seawater showed that the measureable concentrations of DRP were comparable to those obtained by grab sampling. CeO₂-DGT was deployed in sewage sludge, and results showed the ratios (RS) between the concentration (CDGT) by CeO₂-DGT and the concentration (CS) obtained by a traditional centrifugation method ranged from 0.23 to 0.58. This result indicated that sludge solid phase was a potential pool of DRP in sludge solution, and the DRP released from sludge solid phase could compensate partly the consumption of DRP at the interface of DGT device during the deployment. The ratios RS had positive correlation with the content of Fe (r = 0.847, p < 0.01) but were reversed with the level of Ca (r = − 0.879, p < 0.01) in sewage sludge. The proposed method provided a powerful tool for in situ measurement of DRP in natural waters and for release behavior of DRP in sludge.

Desorption of hydrophobic organic contaminants (HOCs) from sedimentary materials plays a vital role in dictating the fate and transport of HOCs in the environment. Desorption irreversibility is a commonly observed phenomenon in laboratory sorption/desorption studies of HOCs. A desorption-resistant fraction (DRF) typically exists during the desorption process. To correctly evaluate the DRF of HOCs can considerably contribute to the understanding of availability and bioavailability of HOCs. This can substantially benefit contaminant remediation and cleanup operations. Conventional batch method to measure the DRF replies on repetitive washing of the sediments, which is time-consuming and can be impractical. This study presents an experimental protocol to quantify the DRF of the sediment-sorbed organic contaminants in a rapid manner. This protocol utilizes cosolvent to expedite desorption kinetics and adopts an ultrafiltration/centrifugation combined method to achieve a complete separation of sediment and solution phases. This proposed experimental protocol can facilitate the quantification of the DRF of sorbed contaminants to understand and minimize the uncertainties associated with risk-based pollution remediation approach. This protocol has the potential to be widely used in environmental studies to characterize sorption and desorption properties of HOCs with soil and sedimentary materials.

The objectives of this study were to characterize the electric conductivity (EC), total dissolved salts (TDS), highly soluble salts (HSS), less soluble salts (LSS), cations (Na⁺, K⁺, Ca⁺⁺ and Mg⁺⁺) and anions (Cl⁻, NO⁻₃, SO⁻⁻₄, PO⁻⁻⁻₄) profiles in non-agricultural coastal land in Gaza Strip and to evaluate the effect of trees in salinity. Six locations were selected randomly in coastal zone in Gaza Strip and used for soil profile digging. Soil samples were collected from different layers between 0 and 150 cm depth, air dried and kept in plastic bags at lab temperature. Ten grams of soil were mixed with 25 mL distilled water and kept under shaking for 24 h, then EC, pH and TDS were determined. Then additional 25 ml distilled water was added to each bottle and kept for additional 24 h of shaking. EC and TDS were determined again. Then the soil filtrates were collected by centrifugation and used to determine cations and anions. Results showed that concentrations of TDS, HSS and LSS were higher at the top soil layer than at deeper soil layers. Concentrations of cations and anions have similar trends to TDS, HSS and LSS. Behavior of cations and anions in the soil profiles under trees were different from those in open field. Comparing between the data of soil profiles under trees (site 2 and 5) and those in the open field (sites 1, 3, 4 and 6) showed slight effects on availability of cations and anions. Strong correlations were found between cations and anions in soil profiles under trees, and week correlations were found in soil profile in open field. In conclusion the coastal soil profiles are characterized with elevated levels of TDS, HSS and LSS in the top soil layers. Accumulations of salts were more pronounced in top soil layers. These properties suggest high potential damage to the ecosystem.