The cadmium (Cd) contamination in the aquatic environment has attracted more and more attention due to its toxicity characteristics, e.g., accumulation in the environment, non-degradability, and the potential threat to the ecosystem. In this research, in order to illustrate the potential threat of heavy metal Cd to aquatic organisms, the online swimming behavior and the continuous acetylcholinesterase (AChE) activity in the gill of Zebrafish (Danio rerio) in 48 h exposure of cadmium chloride (CdCl₂) (4.26 mg/L (0.1 TU, toxic unit), 42.6 mg/L (1.0 TU), and 85.2 mg/L (2.0 TU)) are investigated. The behavior responses of D. rerio based on behavior strength (BS) have obvious dose-effect relationship, and lower BS values could be observed in the dark period at 13–21 h and 37–45 h in all treatments. The circadian rhythm could be observed even in all treatments (0.1, 1.0, and 2.0 TU), and the rhythm was disrupted with 1.0 TU at the end of the experiment whereas the lower (0.1 TU) and higher (2.0 TU) levels showed clear rhythms. These results suggested that the online BS values could illustrate the toxicity of CdCl₂ directly. The AChE activity in the gill is strongly inhibited by CdCl₂ based on the continuous sample results during 48 h exposure. The cross-correlation results using DCCA show a high correlation (r > 0.5) with extreme significance (p < 0.01), which suggest that the exposure in CdCl₂ can affect the AChE activity of D. rerio, and then damage the transduction signal due to neurotoxicity, which may induce decrease of swimming behavior, loss of coordination, and other kinds of behavior changes.

The incidence of Legionella and Acanthamoeba spp. was correlated to microbial indicator analysis and physico-chemical characteristics of rainwater harvested from catchment areas constructed from galvanized zinc, Chromadek®, and asbestos, respectively. Quantitative PCR (qPCR) analysis indicated that no significant difference (p > 0.05) in copy numbers of Legionella spp. and Acanthamoeba spp. was recorded in tank water samples collected from the respective roofing materials. However, significant positive Spearman (ρ) correlations were recorded between the occurrences of Legionella spp. gene copies vs. nitrites and nitrates (p = 0.05) in all tank water samples. Significant positive correlations were also established between Acanthamoeba spp. vs. barium (p = 0.03), magnesium (p = 0.02), sodium (p = 0.02), silicon (p = 0.05), arsenic (p = 0.03), and phosphate (p = 0.01), respectively. Additionally, while no significant correlations were observed between Legionella spp. vs. the indicator bacteria (p > 0.05), positive correlations were observed between Acanthamoeba spp. vs. total coliforms (p = 0.01) and Acanthamoeba spp. vs. Escherichia coli (p = 0.02), respectively. Results obtained in the current study thus indicate that the incidence of Acanthamoeba and Legionella spp. in harvested rainwater was not influenced by the roofing material utilized. Moreover, it is essential that the microbial quality of rainwater be assessed before this water source is implemented for potable and domestic uses as untreated harvested rainwater may lead to legionellosis and amoebae infections.

Mercury (Hg) speciation and bioavailability were studied in surface water, surface sediment and freshwater fish samples collected upstream and downstream of the Medupi (currently under construction) and Matimba power stations in the Waterberg area, Limpopo Province. The initial survey was conducted in May 2010 and continued periodically/seasonally until October 2014. This study was designed to provide an overall description of the levels of Hg in areas potentially impacted by emissions from the coal-fired power station and provide the necessary information to enhance the understanding of the factors regulating the fate and transport of Hg in the environment. Percent loss on ignition (LOI) and ancillary water quality measurements were also carried out. In this study, the total mercury (TotHg) concentrations ranged between 0.92 and 29.13 ng/L, and 0.13 and 8.00 ng/L for methylmercury (MeHg) in water. Total Hg concentrations ranged between 0.50 and 28.60 ng/g, while the MeHg concentration ranged between 0.08 and 2.22 ng/g in sediments. Mercury concentrations in fish ranged between 40 and 1200 ng/g for TotHg, and 13.42 and 600 ng/g for MeHg. Methylmercury concentrations in freshwater fish sampled exceeded the United States Environmental Protection Agency criteria (300 ng/g) in 10% of the total fish sampled and 5% exceeded the WHO guideline (500 ng/g).

Bisphenol A (BPA), a well-known endocrine-disrupting chemical, is receiving increasing concerns regarding its adverse effects on the endocrine system in wildlife and humans. This study was designed to investigate BPA pollution in environmental media in plastics industry areas and to explore the relationship between BPA pollution and the characteristic of different plastics industry. A total of 66 river water samples, 6 aquatic animal samples, and 64 surface soil samples were collected from three cities with different characteristics of plastics industry in southeast China. BPA concentrations in river water (240–5680 ng L⁻¹), aquatic animals (116.13–477.42 ng g⁻¹), and surface soil (38.70–2960.86 ng g⁻¹) were highest in Yuyao City where the plastics industry mainly involved in the production of plastic raw materials. BPA concentrations in Taizhou City were modest and comparable to those reported elsewhere though Taizhou is characterized by its massive production of plastic products. BPA concentrations in Wenzhou City were the lowest where relatively low activities are involved in the plastics industry. Our data indicate that the plastics industry involved the use of BPA as an intermediate in production of raw plastics such as polycarbonate plastics and epoxy resins was the dominant cause of BPA pollution in the surrounding environments. Graphical Abstract Production of raw plastic is the dominant cause of BPA pollution in the environment

Activated carbon-coated electrode was developed and applied in electrostatic precipitator to remove volatile organic compound gases simultaneously with dust particles from a contaminated air. The activated carbon coating mixture was made up of powdered activated carbon (AC), carbon black (CB), and polyvinyl acetate (PVA), and methanol was added as a solvent to control the thickness of the mixture for best coating performance. During the coating process, the Brunauer-Emmett-Teller (BET) surface decreased to 86% of the original AC while pore volume percentages of macro pore increased, compared to micro- and meso-sized pores. The adsorption isotherm of benzene, toluene, ethyl benzene, and xylene (BTEX) gases onto the original AC and AC coating mixture (AC thoroughly mixed with PVA and methanol for coating and powdered again after dry) were tested and compared to each other, and it was found that both isotherm were best fitted to Freundlich and Langmuir isotherm with the order of adsorption capacities; ethyl benzene > m-xylene > toluene > benzene. The difference between adsorption capacities was clearer with the absorbent AC but became little with the AC coating mixture. In removing BTEX at increasing linear velocities up to 6.7 cm/s, it appeared that the surface area of AC electrode was directly proportional to its removal rate of BTEX. The thermal desorption was applied to regenerate the AC electrode, and 200 °C was found to be most efficient for benzene desorption, but higher temperature would be required for entire BTEX gases desorption.

In this study, an iron oxide-coated zeolite (IOCZ) nanocomposite was synthesized and used for the removal of U(VI) and As(III) from aqueous solutions using a batch system. Parameters such as various contact times, pH, competing ions (Cd²⁺, Co²⁺, and Cr³⁺), temperature, and initial concentrations of uranium(VI) and arsenic(III) were investigated. The experimental results were fitted to the Langmuir, Freundlich, and Dubinin–Radushkevich isotherms to obtain the characteristic parameters of each model. Results suggested that adsorption of U(VI) and As(III) by IOCZ was best modeled with the Freundlich isotherm. The kinetic experimental data fitted the pseudo second-order model better than the pseudo first-order model for both elements. Using the thermodynamic equilibrium constants obtained at different temperatures, various thermodynamic parameters, such as ΔG ᵒ, ΔH ᵒ, and ΔS ᵒ, were calculated. These parameters indicated that the process is spontaneous and exothermic in nature. It was noted that an increase in temperature resulted in a decrease of 8.5 and 27.5% for U and As removal, respectively. An increase in initial concentrations of U(VI) and As(III) from 10 to 100 mg L⁻¹ at pH 3 resulted in increased adsorption capacities (q ₑ) for both elements. The increases were from 1.247 to 20.10 mg g⁻¹ for U(VI) and from 3.115 to 54.18 mg g⁻¹ for As(V). The presence of competing ions such as Cd²⁺, Co²⁺, and Cr³⁺ enhanced the removal of As by 9.2% whereas the adsorption capacity of uranium decreased by 13.8%. This research demonstrated that IOCZ is a potential adsorbent for the removal of U(VI) and As(III) from aqueous solutions.

A heterogeneous photo-Fenton process was applied to treat aqueous solutions of indigo blue and textile wastewater using an iron-modified clay (Mt-Fe) and a copper-modified carbon (AC-Cu) as catalysts, the UV radiation source was the sunlight collected by a compound parabolic concentrator (CPC-2D). The treatments were conducted at pH 7.0 and 6.8 for the aqueous solutions and the textile wastewater, respectively, and different hydrogen peroxide concentrations and catalyst quantities were evaluated. The concentration of UV-A radiation collected by the CPC-2D was 54.29 ± 0.71 W/m², with an applied energy of 97.36 kJ from the concentrator device. The indigo blue removal efficiencies for Mt-Fe and AC-Cu were 98% (3 h) and 99% (1.5 h), respectively, using 1.5 g of catalyst, 0.5 M of H₂O₂, and UV radiation. The color removal efficiency in the textile wastewater was 93% after 4 h of treatment using 1.5 g of AC-Cu, 0.5 M of H₂O₂, and UV radiation. The removal of dye and color was improved by using AC-Cu and UV radiation for both systems (the aqueous solutions and the textile wastewater), showing that Cu has an important catalytic activity. IR spectra showed a change after the oxidation of organic matter by heterogeneous photo-Fenton process, and the application of the UV radiation collected by CPC-2D played an important role in the heterogeneous photo-Fenton process.

The adsorption of copper (Cu(II)) from aqueous solutions by activated Luffa cylindrica biochar fibres has been investigated by means of batch equilibrium experiments and FTIR spectroscopy. The effect of various physicochemical parameters, such as pH, initial metal concentration, ionic strength, mass of the adsorbent, contact time and temperature, has been evaluated by means of batch type adsorption experiments. FTIR spectroscopy, as well as acid-base titrations, was used for the characterization of the material and the surface species formed. According to the experimental results even at pH 3, the relative sorption is above 85% and the adsorption capacity of the activated biochar fibres for Cu(II) is q ₘₐₓ = 248 g kg⁻¹. Moreover, the interaction between the surface carboxylic moieties and Cu(II) results in the formation of very stable inner-sphere complexes (∆G ᵒ = −11.2 kJ mol⁻¹ at pH 3 and −22.4 kJ mol⁻¹ at pH 5.5).

Climate change affects water resources worldwide, and Southern Europe is one of the areas where water scarcity is expected to increase in the future. Different water scarcity indicators discussed in this manuscript (e.g. total annual actual renewable water resources, water exploitation index and dependency ratio) showed that some parts of this region are already facing water stress and that climate change could have a great impact on their water supply sector. As agriculture is the biggest consumer of water in the world and also in this particular region, potential water scarcity will impose the need to find new water sources. Treated wastewater reuse would decrease the pressure on the environment and is especially suitable for reuse in agriculture since it already contains some nutrients required for plant growth. However, in order to use it safely, treated wastewater must reach a certain quality that should be regulated. In the south of Europe, 4 countries out of 15 have already adopted wastewater reuse regulations (Greece, Italy, Portugal and Spain). This review compares these regulations and discusses their differences.

In isolated areas without direct human impact where several species of seabirds nest, transformations affecting the soil come mainly from natural processes, such as chemical enrichment caused by seabirds. Penguins constitute an important bird biomass in the Southern Hemisphere, where they breed in colonies on different sites from 100 to thousands of individuals. The accumulation of trace elements and nutrients in soils within two perennial colonies of Humboldt penguins (Spheniscus humboldti) located in north western Chile and three colonies of Adélie penguins (Pygoscelis adeliae) in the Antarctic Peninsula area were investigated here. Surface soil samples were collected directly from nesting sites. Control samples were taken outside the colonies within sites adjacent to the nesting areas, but not affected by bird excrement. The contents of Cd, Co, Cr, Cu, Mo, Ni, Sr, V and Zn were determined by inductively coupled plasma optical emission spectrometry. Ammonium (NH₄) and nitrate (NO₃) ions were determined colorimetrically. Extractable potassium (K) was determined by flame emission spectrometry, and available phosphorus (Olsen-P) was determined by spectrophotometry. The highest concentrations of trace metals (Cd, Co, Cr, Cu, Mo, V and Zn) and macronutrients (available N, K and P), along with an increase in salinity and acidity levels, were found directly below the seabird colony, a situation occurring in northern Chile as well as in the Antarctic Peninsula area, highlighting the role that penguins have as bio-vectors on generating geochemical changes in different ecosystems. Some terrestrial plants and animals that live near those penguin colonies might be affected at a greater level than the organisms that live in sites similar but distant from colonies of birds. New data about the role of these species of seabirds as bio-vectors of chemical contaminants are added.