The green turtle (Chelonia mydas) is listed as a globally endangered species and is vulnerable to anthropogenic threats, including environmental pollution. This study investigated the antimicrobial resistance of Gram-negative bacteria isolated from wild green turtles admitted to a sea turtle rehabilitation center in Taiwan. For this investigation, cloacal and nasal swab samples were collected from 28 green turtles between 2018 and 2020, from which a total of 47 Gram-negative bacterial isolates were identified. Among these, Vibrio spp. were the most dominant isolate (31.91%), and 89.36% of the 47 isolates showed resistance to at least one of 18 antimicrobial agents tested. Isolates resistant to one (6.38%), two (8.51%), and multiple (74.47%) antimicrobials were observed. The antimicrobial agents to which isolates showed the greatest resistance were penicillin (74.47%), followed by spiramycin, amoxicillin, and cephalexin. The antimicrobial-resistance profiles identified in this study provide useful information for the clinical treatment of sea turtles in rehabilitation facilities. The results of our study also imply that wild green turtles may be exposed to polluting effluents containing antimicrobials when the turtles traverse migratory corridors or forage in feeding habitats. To benefit sea turtle conservation, future research should focus on (1) how to prevent pollution from antimicrobials in major green turtle activity areas and (2) identifying sources of antimicrobial-resistant bacterial strains in coastal waters of Taiwan.

Triclocarban (TCC) is used as a broad-spectrum antimicrobial agent, the intensive detection of TCC in aquatic environments and its potential risks to aquatic organisms are concerned worldwide. In this study, 8 Chinese resident aquatic organisms from 3 phyla and 8 families were used for the toxicity tests, and four methods were employed to derive the aquatic life criteria (ALC). A criterion maximum concentration (CMC) of 1.46 μg/L and a criterion continuous concentration (CCC) of 0.21 μg/L were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) derived by species sensitivity distribution (SSD) methods based on log-normal, log-logistic and Burr Type Ⅲ models were 2.64, 1.88 and 3.09 μg/L, respectively. The comparisons of ALCs derived with resident and non-resident species showed that the CMC and CCC of TCC derived with Chinese resident species could provide a sufficient protection for non-resident species. The higher toxicity of TCC on aquatic organisms was found compared with other antimicrobial agents (except for Clotrimazole) in aquatic environment. The strong positive linear correlation was observed between the TCC and TCS concentrations in aquatic environment with a correlation coefficient (R²) of 0.8104, it is of great significance in environmental monitoring and risk assessment for TCC and TCS. Finally, the ecological risk assessment showed that the TCC in Yellow River basin and Pearl River basin had higher risk with the mean potential affected fractions (PAFs) of 9.27% and 7.09%, and 22.10% and 15.00% waters may pose potential risk for 5% aquatic organisms, respectively. In general, the risk of TCC in Asian waters was higher than that in Europe and North America.

Increasing attention has been attracted in developing new technologies to remove chlorofene (CF) and dichlorofene (DCF), which were active agents in antimicrobials for general cleaning and disinfecting. This study investigated the significant influences of bicarbonate (HCO3−) on the degradation of CF and DCF in the Cu(II)-mediated Fenton-like system Cu2+/H2O2. Our results indicate that HCO3− may play a dual role to act 1) as a ligand to stabilize Cu(II), forming soluble [CuII(HCO3−)(S)]+ species to catalyze H2O2 producing hydroxyl radical (OH) and superoxide ion (O2−) and 2) as a OH scavenger. Furthermore, the reaction kinetics, mechanisms, and intermediates of CF and DCF were assessed. The apparent rate constants of CF and DCF were enhanced by a factor of 8.5 and 5.5, respectively, in the presence of HCO3− at the optimized concentration of 4 mM. Based on the intermediate identification and frontier electron densities (FEDs) calculations, the associated reaction pathways were tentatively proposed, including C–C scission, single or multiple hydroxylation, and coupling reaction. In addition, significant reduction in the aquatic toxicity of CF and DCF was observed after treatment with Cu2+/H2O2–HCO3- system, evaluated by Ecological Structure Activity Relationships (ECOSAR) program. These findings provide new insights into Cu(II)-mediated reactions to better understand the environmental fate of organic contaminants in carbonate-rich waters.

There is a growing interest in the occurrence and sources of pharmaceutical substances in the environment. This paper reports the first detailed transect of pharmaceutical occurrence along the River Thames, UK, from source to sea, undertaken during a period of high flow in 2016. In 37 samples a total of 41 pharmaceuticals and 2 lifestyle compounds (cocaine and sucralose) were detected. Total concentration of pharmaceuticals ranged from 0.0012 μg/l to 10.24 μg/l with a median of 2.6 μg/l. Sucralose concentrations varied from <0.01 to 5.9 μg/l with a median concentration of 1.93 μg/l and was detected in every sample except the groundwater-dominated sources of the Thames. Antimicrobials, including those on the surface water watch list (erythromycin, clarithromycin and azithromycin) were detected in every site downstream of the Thames source. Diclofenac, recently on the surface water watch list, was detected in 97% of Thames samples and above the proposed EQS of 0.1 μg/l in 12 samples. Distinct increases in concentration and number of pharmaceuticals were found downstream of the Oxford, Mogdon and Hogsmill wastewater treatment works (WWTW) but were more subdued downstream of the Crossness and Beckton WWTW due to the tidal nature of the Thames and combined sewer outflows. Sucralose was found to be an excellent tracer of wastewaters (treated and untreated) and can be used as a proxy for many pharmaceuticals. Paracetamol and ibuprofen were tracers of untreated wastewater inputs to the Thames due to their high biodegradation within WWTWs.

This study analyzes changes in the total (intrinsic and acquired) resistance of autochthonous bacteria in a river which is a receiver of treated wastewater. In the analyzed samples, tetracycline contamination levels were low and characteristic of surface water bodies. An increase in the populations of tetracycline-resistant and fluoroquinolone-resistant microorganisms was noted in downstream river water samples in comparison with upstream river water samples, but the above trend was not observed in bacteria resistant to macrolides and β-lactams. The counts of doxycycline-resistant bacteria (DOXR) were significantly correlated with doxycycline levels. The minimum inhibitory concentrations (MICs) for doxycycline in DOXR isolates were higher in downstream river water than in upstream river water samples. The discharge of treated wastewater had no effect on the multi-drug resistance of oxytetracycline-resistant and doxycycline-resistant isolates. The results of the experiment indicate that the presence of doxycycline-resistant bacteria is a robust indicator of anthropogenic stress in river water.

New analytical methods are needed to efficiently measure the growing list of priority pharmaceuticals in environmental samples. In this regard, a rapid, sensitive, and robust method was developed for quantitation of 168 pharmaceuticals and pharmaceutical metabolites using solid-phase extraction (SPE) and liquid chromatography with tandem mass spectrometry. The extraction protocol and instrumental efficiency were specifically addressed to increase analytical workload and throughput. The optimized protocols, which are five times more efficient than US EPA Method 1694, enabled analyte recoveries that ranged from 77% to 117% for 162 analytes with method quantitation limits (MQLs) as low as 0.1 ng L⁻¹. To verify the suitability of the improved analytical method for environmental samples, 24-h composite samples of raw wastewater and wastewater effluent, along with downstream surface water, were analyzed. Overall, 143/168 target compounds were identified in at least one of the samples, and 130/168 analytes were present at concentrations above their MQLs. The total mass concentration of the measured analytes decreased by 93% during wastewater treatment. The analyte concentrations in the wastewater effluent were comparable to those measured in surface water 1 km downstream of the wastewater discharge point. Ultimately, the comprehensive method will serve as an important tool to inform the occurrence, fate, transport, and toxicity of a large suite of priority pharmaceuticals and pharmaceutical metabolites in natural and engineered systems.

The increased use of disinfectants due to the spread of the novel coronavirus infection (e.g. COVID-19) has caused burden in the environment but knowledge on its ecotoxicological impact on the estuary environment is limited. Here we report in vivo and molecular endpoints that we used to assess the effects of chloroxylenol (PCMX) and benzalkonium chloride (BAC), which are ingredients in liquid handwash, dish soap products, and sanitizers used by consumers and healthcare workers on the estuarine rotifer Brachionus koreanus. PCMX and BAC significantly affected the life table parameters of B. koreanus. These chemicals modulated the activities of antioxidant enzymes such as superoxide dismutase and catalase and increased reactive oxygen species even at low concentrations. Also, PCMX and BAC caused alterations in the swimming speed and rotation rate of B. koreanus. Furthermore, an RNA-seq-based ingenuity pathway analysis showed that PCMX affected several signaling pathways, allowing us to predict that a low concentration of PCMX will have deleterious effects on B. koreanus. The neurotoxic and mitochondrial dysfunction event scenario induced by PCMX reflects the underlying molecular mechanisms by which PCMX produces outcomes deleterious to aquatic organisms.

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world’s rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals.