Plastics have become strong environmental stressors of coastal marine ecosystems. Their introduction into the marine ecosystem is subjected to different mechanisms, including the inadequate disposal of solid waste and dumping of wastewater. In addition, their chemical composition makes them resistant to variables such as temperature and salinity of water. These polymers are degraded and fragmented mainly due to the action of the waves, which results in the formation of smaller particles called microplastics. Microplastics are characterized by being persistent in the environment due to their low biodegradation, and although they have a maximum size of 5 mm, there is a wide range of sizes suggested by different authors. According to their use, microplastics can be classified as primary when they are recognized at first sight, and as secondary, when they are gradually divided. Microplastics have become a potential risk to the health of marine species due to their small size, and the risk to human health due to their persistence through trophic chains is alarming. Given the potential impact these materials would have in the biota, and the need to assist the different regulatory agencies to develop political acts on the proper management and disposal of microplastics, the aim of this work was to identify different research carried out at international level on established methodologies for studies of identification and quantification of microplastics, bacterial communities, and contaminants adhered to microparticles. Given the above, some methodologies have been identified and used in various studies for the identification and quantification of these materials on beaches. It should be noted that in different countries, there has been an increase in research related to contamination by microplastics on beaches, in which bacterial communities attached to these plastic particles have been also identified. Likewise, not only the risks and threats have been determined for marine species but also for the health of people who frequent tourist places such as beaches.

In this study, a farmland contaminated by heavy metals (Cu, Zn, Ni, and Cr) was selected to evaluate the performance of poly-γ-glutamic acid (γ-PGA) on the removal of heavy metals in soil washing. The highest heavy metal concentrations at the contaminated site were Cu: 1180 mg/kg, Zn: 1450 mg/kg, Ni: 287 mg/kg, and Cr: 316 mg/kg. Batch experiments designed by Taguchi Method were conducted first to assess the effect of different washing conditions on the removal of heavy metals in laboratory. The results of batch experiments show that factors that affected the removal efficiency of heavy metals was of the order γ-PGA concentration > washing time > liquid/soil ratio > rotational speed. The optimal operating parameters for heavy metal removal were γ-PGA 3.5%, liquid/soil ratio 15/1, washing time 60 min, and rotational speed 100 rpm. Under the optimal conditions, up to 50.7% of the major target metal, Cu, was removed. Heavy metals in the soil were mainly Fe-Mn oxide bound and organically bound. On-site treatment using the optimal operating parameters caused 54.3% of Cu removal. When the soil was washed 3 times by γ-PGA, the removal efficiency of Cu was improved to 74.3%. After the treatment, the change in soil bacterial number was insignificant, indicating that γ-PGA is an environmentally friendly washing reagent.

FeMnMg-LDH with hydrotalcite-like structure was synthesized via a coprecipitation method and applied to copper ion removal from aqueous solution. FT-IR, SEM, PXRD, TEM, and XPS were applied to characterization analysis. Factors like temperature, pH, contact time, initial concentration, and coexisting cations were systematically studied. FeMnMg-LDH has an excellent performance on copper adsorption, with a maximum capacity of 204.07 mg/g at 25 °C, which is much higher than that of most other similar LDHs. The effects of coexisting cations on the removal efficiency of copper ions are various and following the order of Zn²⁺ > Pb²⁺ > Mg²⁺ > Ca²⁺, which may be due to the solubility of their hydroxides. The result of adsorption thermodynamics indicates that the adsorption process is endothermic and spontaneous. The adsorption kinetics are in accord with the pseudo-second-order kinetic model, and particles that appear in the SEM figures are both suggesting that chemical complex formed during the adsorption process. Meanwhile, the result of DKR model fitting indicates that the isomorphic substitution mechanism is involved in the adsorption process. Thus, the main adsorption mechanisms of FeMnMg-LDH in the removal of Cu²⁺ from aqueous solution in this study are isomorphic substitution and surface-induced precipitation. Graphical abstract

Basil (Ocimum basilicum L.) is a hyperaccumulative herbaceous plant that has the ability to grow in contaminated soils and is believed to harbor a wide variety of bacterial species resistant to recalcitrant toxic chemical compounds. The objective of this work was to evaluate the potential for removal of decaclorobiphenyl PCB-209 by bacteria associated with the O. basilicum plant. A total of 34 endophytes and 52 strains from the rhizosphere of this plant were isolated using selective culture media. The adaptive capacity of the bacteria in phenol and Arochlor 1242 was initially determined and then a set of bacteria was selected and their removal potential of decachlorobiphenyl PCB-209 was evaluated. The phylogenetic analysis of 16S rRNA gene grouped to the O. basilicum isolates within bacterial genera Acinetobacter, Bacillus, Lysinibacillus, Novosphingobium, Pseudomonas, Rhizobium, Sphingobium, Stenotrophomonas, and Terribacillus as well as bacterial strains Pseudomonas taiwanensis BS-1, Rhizobium nepotum BS-2, Terribacillus sacharophilus BS-3, Stenotrophomonas rhizophila BS-4, Bacillus arybhattai BS-5, and Lysinibacillus macroides BS-6 showed the ability to adapt and use phenol and Arochlor 1242 as source of C. The strains BS-4 isolated from the root of the plant showed a higher potential from the removal of the PCB-209 (390.75 mg L⁻¹) at an initial concentration of 500 mg L⁻¹ and also had the ability to synthesize biosurfactant (EI = 60%) compared to the other strains evaluated. The diversity of bacteria associated to O. basilicum had biological qualities that may contribute to their adaptation and proliferation in an environment contaminated by PCB and be used efficiently as bioremediation to relieve agricultural soils contaminated by persistent organic compounds.

Hydrochars produced from hydrothermal carbonisation of faecal simulant (FS) at 180 °C for 30 min and sewage sludge treated via CAMBI process at 165 °C for 30 min were used for adsorption of organic pollutants in effluent from an anaerobic digester (AD). The adsorption potential of the hydrochars investigated was compared with that of a commercial powdered activated carbon (PAC). It was found that the CAMBI and FS hydrochars were effective only after chemical activation. KOH activation increased chemical oxygen demand (COD) removal from 33.0 to 59.6% and 75.2% for FS and CAMBI, respectively. Extra activation with HCl improved the adsorption efficiency of FS, increasing COD removal to 79.3%, but not for the CAMBI hydrochar even though its surface area was increased. Acidic pH aided organics removal for both hydrochars. PAC adsorption capacity was the highest (> 90%), and this was not affected by pH. All the adsorbents could successfully remove the organics in a very short time as 30 min. The optimum dosage of the hydrochars to reach a high uptake of organics was 30.0 g/L. The adsorption reaction followed a pseudo-second-order kinetic model for all the hydrochars. The adsorption onto the hydrochars correlated well with Temkin isotherm model and followed a type II and IV isotherm type, except PAC which was described by the Langmuir isotherm with a high adsorption capacity of 400.0 mg/g. The study demonstrated that hydrochars of FS and CAMBI activated with KOH are efficient and sustainable adsorbents for the removal of organics from AD effluent.

The discharge of ship ballast water (containing large amounts of alien organisms) has caused severe ecological hazards to marine environments. In this study, three metal elements (Ag, Fe, and Gd) were doped to nano-TiO₂ material respectively (content: 0.4%, 0.7%, and 1.0%) to improve inactivation effect of Escherichia coli and Enterococci in ballast water. Experimental results indicate that compared with the sole ultraviolet (UV) and the UV and original nano-TiO₂, the UV and metal-doped nano-TiO₂ increased the bacterial inactivation rate to different extents. For each metal element, high external metal content (1.0%) corresponded to high inactivation effort. The doping of Ag resulted in optimal inactivation effort, and the addition of Fe and Gd caused unobvious effort. At the end of the inactivation process (20 s), the UV and 1% Ag-doped nano-TiO₂ reached the highest logarithmic sterilization rates (0.915 for Escherichia coli and 0.805 for Enterococcus). The doping of Ag, Fe, and Gd did not change the anatase phase TiO₂ crystal form, and 1% Ag-doped nano-TiO₂ had the smallest particle diameter and the evenest distribution of nanoparticles. Compared with the sole UV, the UV and Ag-doped nano-TiO₂ treatment resulted in higher malondialdehyde contents (0.0646 μmol/L for Escherichia coli and 0.0529 μmol/L for Enterococci) and lower superoxide dismutase activities (0.672 U/mL for Escherichia coli and 0.792 U/mL for Enterococci), which were in accordance with high inactivation rates in these cases.

Several epidemiological studies have investigated the adverse health effects of air pollution, but studies reporting its effects on allergic rhinitis (AR) are limited, especially in developing countries having the most severe pollution. Limited studies have been conducted in China, but their results were inconsistent. So, we conducted a time-series study to evaluate the acute effect of six air pollutants (fine particulate matter [PM₂.₅], particulate matter with diameter less than 10 μm [PM₁₀], sulfur dioxide [SO₂], nitrogen dioxide [NO₂], ozone [O₃], and carbon monoxide [CO]) on hospital outpatient visits for AR in Xinxiang, China from January 1, 2015, to December 31, 2018. An over-dispersed Poisson generalized additive model adjusting for weather conditions, long-term trends, and day of the week was used. In total, 14,965 AR outpatient records were collected during the study period. Results found that each 10 μg/m³ increase in PM₂.₅, PM₁₀, SO₂, NO₂, O₃, and CO corresponded to 0.70% (95% confidence interval 0.00–1.41%), 0.79% (0.35–1.23%), 3.43% (1.47–5.39%), 4.54% (3.01–6.08%), 0.97% (− 0.11–2.05%), and 0.07% (0.02–0.12%) increments in AR outpatients on the current day, respectively. In the stratification analyses, statistically stronger associations were observed with PM₂.₅, PM₁₀, SO₂, NO₂, and CO for AR outpatients < 15 years of age than in those 15–65 and ≥ 65 years of age, whereas the opposite result was found with O₃. Associations between PM₁₀, SO₂, NO₂, O₃, and AR outpatients were higher in the warm season than those in the cool season. This study suggests that exposure to PM₂.₅, PM₁₀, SO₂, NO₂, and CO was associated with increased AR risk and children younger than 15 years might be more vulnerable.

The Nevado de Toluca Natural Protected Area (Zona de Protección de Flora y Fauna Nevado de Toluca, ZPFFNT), Central Mexico, encompasses one of the four highest (> 4000 m a.s.l.) volcanoes in Mexico, Nevado de Toluca; an extended area of woodland surrounds this volcano. Although identified as a remote area based on its high altitude, the ZPFFNT is not far from the urban and industrial zones of Toluca (~20 km) and Mexico (~72 km) cities, which potentially threatens the environmental health of the ZPFFNT by emitting SO₂ and NOX. Acid precipitation falling on areas with low alkaline reserve leads to environmental acidification and land degradation. To provide reliable data on the air pollution reaching the ZPFFNT and the related potential risks, our study analyzed the bulk atmospheric deposition chemistry and its temporal dynamics throughout an annual cycle. There are two well-defined seasons: (a) cold/dry with SW–NE wind direction and (b) warm/rainy with NE–SW wind direction. The pH, electric conductivity (K₂₅), cations, Cl⁻, and HCO₃⁻ were statistically higher in the cold/dry period. Differently, NO₃⁻ and SO₄²⁻ showed steadier behavior. Bulk deposition pH remained acidic at all times but reached extreme low values from July to September during the warm/rainy season. In the cold/dry season, alkaline cations were important in partially neutralizing the acidic compounds from the urban and industrial zones of Toluca and Mexico cities. Previously assumed to be safe based on its remoteness, the ZPFFNT is threatened by acid precipitation, which demand the implementation of preventative and mitigating actions as part of a management plan to avoid environmental deterioration.

In the treatment of wastewater from vehicle washing, the coagulation/flocculation process using inorganic coagulant is mostly applied; it may or may not be combined with other processes. In literature, few studies use natural coagulants and assess the surfactants’ removal among the physical-chemical parameters, particularly using the adsorption process. In order to fill this knowledge gap, this work aimed to treat the car wash wastewater, applying a combined process of coagulation/flocculation/sedimentation (C/F/S) and adsorption. Process efficiency was evaluated according to the removal of color, turbidity, total solids, volatile solids, total dissolved solids, chemical oxygen demand and surfactants. For primary effluent treatment, C/F/S experiments were performed with Tanfloc SG to investigate the influence of the natural coagulant concentration in color and turbidity removal efficiency. The results showed that 220 mg L⁻¹ was the best coagulant concentration (turbidity = 97.5%; color = 92.5%) (p < 0.05). The supernatant of the C/F/S process was applied to the sequential adsorption process (kinetics and isotherm) with mineral activated carbon. The equilibrium time of the kinetic experiment was established after 2 h of contact, and the Langmuir isotherm model best described the surfactant adsorption behavior (R² = 0.93; qₘₐₓ = 5.65 mg g⁻¹). The combined process enhanced the treatment efficiency achieving an overall removal efficiency of 97.3% for color, 98.8% for turbidity, 92.6% for chemical oxygen demand, and 97.2% for surfactants. The combined process proved to be promising for the treatment of car wash wastewater, presenting a reduction surfactant concentration and on the other parameters evaluated, contributing to environmental sustainability.

Vigorously developing high-tech industry has been considered to be an effective way to coordinate economic growth with excessive carbon dioxide (CO₂) emissions. However, previous studies have not explored the heterogeneous impacts of high-tech industry on CO₂ emissions in regions with different levels of high-tech industry development, and not distinguished the direct and indirect impacts. Based on STIRPAT model, this study investigates the impacts of high-tech industry development on CO₂ emissions in China between 2005 and 2016. Adopting the K-medians cluster method, effects in regions with high, middle, and low levels of high-tech industry development are considered. Indirect effects of high-tech industry development on CO₂ emissions by affecting industry structure upgrades and economic growth are explored. Empirical results illustrate a positive U-shaped nonlinear link between the level of high-tech industry development and CO₂ emissions at the national level and regional (high, middle, and low) level. In terms of indirect impacts, high-tech industry development attenuates the reduction of CO₂ emissions due to industry structure upgrades, and promotes economic growth to increase CO₂ emissions slightly. The indirect impact intensity gradually decreases as the level of high-tech industry development decreases across three regions. Reasonable implications of our findings are proposed.