17α-ethinylestradiol (EE2), the female contraceptive pill, has been detected in mediterranean coasts where seahorse populations, Hippocampus guttulatus, live. Low environmental concentrations have the potential to disrupt growth but also endocrine metabolism, and this imbalance is all the more critical in early life stage. To investigate the impact of EE2 in reared seahorses, we exposed aged 2 months and sexually undifferentiated seahorses to an environmental concentration of 21 ng/L of EE2 for a period of 30 days. EE2 exposure led to a 19% reduction in weight, but also a mortality rate of 27%. This exposure predicted demasculinization of male individuals with a late onset of secondary sexual characteristics. EE2 exposure led to an increase of the free androgen index, but significant reductions of estradiol and testosterone in males were observed. This low estrogen concentration seemed to impact the positive feedback on luteinizing hormone (LH) with a decrease in LH production. Added to this, synthetic estrogen had a negative impact on the production and the release of follicle-stimulating hormone. Contrary to all expectations, females demonstrated a significant decrease in vitellogenin, following exposure to EE2 at 21 ng/L, while no changes were detected in males. This first study on the European long-snouted seahorses confirmed the deleterious impact of the female contraceptive pill with a real impact on growth, sexual differentiation, and maturation in young immature seahorses.

Individuals with higher contaminant burdens are expected to be in poorer physical health and be of lower individual body condition and energetic status, potentially resulting in reduced ornamentation or increased asymmetry in bilateral features. The degree and magnitude of this effect also would be expected to vary by sex, as female birds depurate contaminants into eggs. We tested for relationships among mercury in feathers, sex, and elaborate feather ornaments that relate to individual quality in crested auklets (Aethia cristatella), small planktivorous seabirds in the North Pacific Ocean. We found no relationships between mercury and the size of individuals’ forehead crest or degree of measurement asymmetry in auricular plumes, both of which are favoured by intersexual selection. Females had significantly greater mercury concentrations than males (females. 1.02 ± 0.39 μg/g; males, 0.75 ± 0.32 μg/g); but concentrations were below that known to have physiological effects, as expected for a secondary consumer. Sex differences in overwintering area for this long-distance migrant species (more females in the Kuroshio Current Large Marine Ecosystem than males) could be the reason for this seemingly counterintuitive result between sexes. Further research relating mercury burden to overwintering ecology and diet contents would build on our results and further elucidate interrelationships between sex, sexually selected feather ornaments and contaminant burden.

Plastics are widely considered to be a major threat particularly in the urban areas owing to extensive use of plastic products. The current study is the first investigation to highlight the microplastics (MPs) pollution from the freshwater (Ravi River) located in the predominant urban center, i.e., Lahore, Pakistan. The concentration profile was quantified from surface water (n = 19) and sediments (n = 19) collected from different drains and canals of predominant freshwater resources in Lahore, Pakistan. The highest content of MPs was observed in the sullage carrier with mean concentration of 16,150 ± 80 MPs/m³ and 40,536 ± 202 MPs/m² in the water and sediments respectively. The lowest level was detected in the link canals with mean concentration of 190 ± 141 MPs/m³ in the water and 683 ± 479 MPs/m² in the sediments. The proportion of large size MPs (300 μm–5 mm) was maximum in the upstream section of Ravi river, whereas fine size MPs (50–150 μm) were dominant in the downstream section. In terms of shapes, the fragments were predominant with a relative abundance of 56.1% and 83.1% followed by fibers with a relative abundance of 38.6% and 11.8% in the water and sediments respectively. The chemical composition analysis showed that most of the fibers, fragments, and beads were polyethylene while the sheets were composed of polypropylene. Nevertheless, the foams isolated from the samples were composed of polystyrene. Within 24 h, about 2.4 ± 2.4 billion microplastic pieces were estimated to be transported from a single water channel into the river. The highest discharge of MPs was estimated from the sullage carrier with about 7 billion pieces/day.

Removal of toxic Cr(VI) from contaminated water is significant for environmental protection. High efficient adsorbents with outstanding adsorption performance are highly demanded. Herein, we reported that window-like structured carbon hollow fibers (WL-CHF) derived from Enteromorpha prolifera could capture toxic Cr(VI) from aqueous solutions with high adsorption capacity, fast adsorption rate, and excellent recyclable performance. The excellent adsorption performance could be attributed to the unique structure that combines a variety of advantages: large specific surface area, fast diffusion processes, and easy access of adsorption sites for Cr(VI). In addition, the adsorption process was fitted well with pseudo-second-order model and Langmuir isotherm model. The potential mechanism on Cr(VI) removal includes reduction-cation exchange and electrostatic interaction with surface oxygen-containing functional groups. This study highlights new opportunities for designing adsorbents for Cr(VI) removal from Cr-polluted water.

Marine diesel engines produce a lot of exhaust gas (NO, SO₂). Based on the situation that wet scrubbing methods have been already applied to ship desulfurization and seawater is easily accessible around the ships, this paper proposed a novel AOP (advanced oxidation process) of NaClO₂ (sodium chlorite) with Cl⁻ (abundant Cl⁻ exist in seawater) to remove NO from the flue gases of marine engines. The buffer capacity of NaAC (sodium acetate), the effect of Cl⁻ concentration, and Cl⁻ promotion mechanism on NO removal were investigated. The result showed that the existence of NaAC in solution could inhibit the rapid decline of the solution pH. The addition of Cl⁻ achieved a remarkable promotion to NO removal at lower NaClO₂ concentration, which was due to the fast generation of ClO₂ from the promotion decomposition of NaClO₂ by Cl⁻ in acidic condition. Then, the thermodynamic and dynamic mechanism of the generation of ClO₂ was intensively analyzed. And the mechanism of NO removal was discussed finally.

Atmospheric deposition particles are fine-sized having a high adsorption capacity. Therefore, they can easily transfer the contamination to other areas. Plants can absorb certain pollutants using their leaves and then accumulate them in their biomass. In this study, the spatial and temporal variability of air pollution was assessed using pine needles as the bioindicators of atmospheric pollution. The magnetic susceptibility (MS) at low and high frequencies (χₗf, χₕf) and the concentration of selected heavy metals of pine needles (Pinus mugo) were estimated in order to address the possible relationships between needles’ MS and the heavy metal concentration in the city of Isfahan, central Iran. In addition, the relationship between the heavy metal concentration of pine needles and that of the atmospheric dust was examined using the published data. Tree pine needles were monthly sampled, from April to December 2015 (T1–T9), during 9 months, from 30 different sites in the Isfahan city. There were two treatments including washed + unwashed (WU) and washed + washed (WW). The heavy metal total concentrations including Zn, Fe, Cu, Co, Pb, and Ni were measured. The mean concentrations of Fe, Zn, Pb, Cu, Ni, and Co were 80.4, 3.9, 1.8, 1.4, 0.6, and 0.3 mg kg⁻¹, respectively. The results revealed that the concentration of heavy metals and MS in the pine needles followed the order Fe > Zn > Pb > Cu > Ni > Co. Also, the heavy metal concentration in the pine needles with different treatments had the following trend: WU > WW. It was shown that there was a significant correlation (p < 0.01) between the heavy metal concentrations and the leaf MS values of the pine needles and the concentration of heavy metals in atmospheric dust. Besides, similar trends were detected for the spatial variability of heavy metals and the pine needles’ MS. In general, it could be concluded that the biomagnetic approach could serve as a comparatively fast and low-cost method to detect highly polluted urban areas with selected heavy metals, particularly the areas which are under the influence of anthropogenic and other traffic-related sources.

Submerged macrophytes and phytoplankton assemblage play significant roles in the functioning of aquatic ecosystems. An experiment was carried out in Beijing in order to further evaluate the environmental factors that affect the growth of submerged macrophytes and phytoplankton assemblage. Submerged macrophytes (i.e., Vallisneria natans, Hydrilla verticillata, and Ceratophyllum demersum) constructed the growth system with some controllable influencing factors (i.e., the flow rate and water depth gradient). The flow rates were set separately as 4 L/h (1#), 6 L/h (2#), and 12 L/h (3#), while the water depth gradient was of 0.5–1.7 m in eutrophic water. Generally, all macrophytes could grow normally in the experiment, and the system could maintain and improve the effluent quality. The average removal rates of NH₃-N, COD, NO₃-N, TN, and TP were about 90%, 33%, 65%, 45%, and 40%, respectively. Seen from the results of the water depth gradient experiments, it is indicated that Vallisneria natans grows better in shallow water (0.5 m) and moderate shallow water (0.7 m) area, with an average relative growth rate (ARGA) of 57%. Hydrilla verticillata and Ceratophyllum demersum grow better in moderate deep water (1.2 m) and deep water (1.7 m) area (ARGA of 66% and 64%, respectively). Results of the flow rate experiments showed that the moderate flow rate (6 L/h) was the best for those three macrophytes’ growth. As the fitting results of the rapid light curves (RLCs) showed that the utilization of light and the tolerance to strong light were different for these macrophytes, if they are ranked in the order of the utilization and the tolerance from strong to weak, they are Hydrilla verticillata, Ceratophyllum demersum, and Vallisneria natans. Microbial analyses indicated that the overall system diversity of the experimental groups have been improved after cultivation of macrophytes. However, the accumulated Cyanobacteria caused by the low flow rate (1#) would lead to the suppression of microbial organics decomposition and nutrient metabolism in the macrophytes. To sum up, the results of this study provided theoretical guidance and technical support for the restoration of submerged macrophytes in eutrophic water.

This paper empirically examines the environmental Kuznets curve (EKC) hypothesis using a country’s water stress as an indicator of the pressure on renewable water resources. The sample consists of 9 European countries by covering the period 1995–2013. The paper adopts a panel threshold regression model which can predict the threshold level endogenously to analyze whether income per person has an impact on water stress. The empirical findings strongly demonstrate the existence of a threshold beyond which environmental pressures of GDP (real) per capita growth on renewable water resources tend to increase. The growth below the threshold levels has no statistically significant effect on water stress, while the growth rate above the threshold increases stress on water resources. The available empirical findings obtained, albeit limited, tend not to support the EKC hypothesis, which postulates an inverted-U-shaped relationship.

Release of harmful organic intermediates or byproducts during the manufacture of petrochemical compounds is a serious problem in petrochemical plants. In this work, polysulfone membranes blended with GO/TiO₂ nanocomposite were synthesized by phase inversion method and coated with a polyamide layer formed by interfacial polymerization to prepare a thin-film composite (TFC) sample. Analysis and characterization of the sample were carried out by XRD, FE-SEM, BET, FTIR/ATR, AFM, TGA, and zeta potential. Results indicated that incorporation of GO/TiO₂ into the membrane structure enhanced porosity, surface roughness, and macrovoid formation along the cross-section of the sublayer and permeability of the membrane. The TFC membranes were applied to remove mononitrotoluene (MNT) and dinitrotoluene (DNT) as the basic intermediates of toluene diisocyanate (TDI). The membranes demonstrated high efficiency (> 90%) for the removal of MNT and DNT according to the charge exclusion mechanism and Donnan effect. Application of the TFC membrane for treatment of wastewater in the TDI plant showed that the removal of pollutants is variable in the range of 45–65% and 53–69% for the membrane with the highest flux and highest rejection in different transmembrane pressure, respectively.

Irrespective of how plastics litter the coastline or enter the sea, they pose a major threat to birds and marine life alike. In this study, an artificial intelligence tool was used to create an image classifier based on a convolutional neural network architecture that utilises the bottleneck method. The trained bottleneck method classifier was able to categorise plastics encountered either at the shoreline or floating at the sea surface into eight distinct classes, namely, plastic bags, bottles, buckets, food wrappings, straws, derelict nets, fish, and other objects. Discerning objects with a success rate of 90%, the proposed deep learning approach constitutes a leap towards the smart identification of plastics at the coastline and the sea. Training and testing loss and accuracy results for a range of epochs and batch sizes have lent credibility to the proposed method. Results originating from a resolution sensitivity analysis demonstrated that the prediction technique retains its ability to correctly identify plastics even when image resolution was downsized by 75%. Intelligent tools, such as the one suggested here, can replace manual sorting of macroplastics from human operators revealing, for the first time, the true scale of the amount of plastic polluting our beaches and the seas.