Surface waters are exposed during their journey to various types of pollutants plus the contribution they receive from different effluents. The objective of this investigation was to evaluate the concentration of Pb, Cd, and Cu in surface waters of the Cotaxtla-Jamapa basin in Veracruz, Mexico. Analyzes were carried out in triplicate in six sampling sites, during three seasons, in morning, and night hours. At the sampling sites, Bocana and Arroyo Moreno, concentrations higher than the maximum permissible international limits of Pb and Cd were reported. The Pb, by time of sampling, presented significant statistical differences (p < 0.05) in three seasons of the year, in contrast to Cd and Cu. The above results indicated a risk in the use of water from the Cotaxtla-Jamapa basin, despite the fact that the concentrations obtained according to the national limits for NOM-001-SEMARNAT were not exceeded. It is necessary to update the national legislation to ensure the reduction of risk from exposure to heavy metals and to ensure conservation in terms of environmental quality.

During storm events, contaminants and sediments from roadways, curbside, parking lots, and lawns in urban environments are mobilized and transported by the stormwater runoff. These contaminants are finally discharged in waterbodies, such as rivers and lakes, with adverse effects on public health and ecosystems. Several studies have reported high levels of heavy metals and nutrients in urban stormwater runoff. Best management practices such as sedimentation and bioretention are not practical in urban environments due to the lack of adequate space; however, filtration systems, such as an in-ground permeable filter system, are being developed because they are practical and feasible. Four different filter materials (calcite, zeolite, sand, and iron filings) were effective in removing individual contaminants (Cd, Cu, Ni, Cr, Zn, nitrate, and phosphate) in tests at 24 h. The present investigation assessed the removal kinetics of contaminants from a simulated stormwater consisting of multiple heavy metals and nutrients by the four filter materials. Batch experiments were conducted to evaluate the removal kinetics of co-existing heavy metals and nutrients from the simulated stormwater. The rate of contaminant removal and overall removal efficiency was found to be dependent on the filter material and contaminant nature, as well as the induced pH changes caused by the filter media. The zero-order kinetic model best described the removal rate of Cu and Ni by sand. The first-order kinetic model was only applicable for nitrate removal by iron filings, and the second-order kinetic model described the removal rates of other contaminants and filter media combinations.

The present work describes the synthesis of α-MnO₂ nanorods using a natural extract of Brassica oleracea (cabbage) and the formulation of its nanohybrids with polycarbazole, i.e., α-MnO₂/PCz. Synergistic interaction between PCz and MnO₂ is revealed from infrared spectroscopy (IR) studies while the composition is determined by X-ray photoelectron spectroscopy (XPS). The formation of α-MnO₂ nanorods is confirmed via high-resolution transmission electron microscopy (HRTEM). The indirect bandgap of α-MnO₂ is reported as 2.5 eV while for the nanohybrids it is found to be ranging between 2.3 and 2.5 eV. Results show that 91% and 89% of degradation is achieved within 30 min and 90 min under the microwave and UV irradiation respectively. Hydroxyl radicals (•OH) and superoxide (•O₂⁻) radicals are responsible for photocatalytic degradation of the drug Bactrim DS which is confirmed by radical scavenging experiments. The nanohybrids show promising catalytic activity under UV as well as microwave irradiation.

The dynamics in climatic variability is prominently affecting the agriculture system, particularly the small and marginal land holding farmers in arid and semi-arid regions which are highly vulnerable. The present study in Kolar district assessed the variability scale and dynamics of rainfall over the decades, it revealed the current day’s agrarian crisis, resulting in impacts on farmers and adaptations by farmers to changing situations. The study also reveals that over the decades there has been a considerable variation in rainfall pattern in the study area but there was no significant average rainfall variation till the last decade, after which there was a significant seasonal variation that directly affects the sowing pattern and associated agricultural practices. The exploitation of groundwater for water-intensive commercial crops has increased rapidly from the past decade that resulted in the critically depleted groundwater table. To meet the livelihood demands some farmers were observed to have shifted to non-agricultural occupations. It is a serious threat at this point of time as the agriculture output has to be fed to the larger portion of the society and decreased output from agriculture eventually leads to inflation. So, it is very crucial to adapt all possible measures to retain farmers in agriculture practice. Hence, understanding and scientific assessment of the risks associated with the changing climate and its variables is the need of the hour, particularly in arid and semi-arid regions which are going to be highly vulnerable. Studies like this will help in policy-making and management planning to cope up with the dynamic climatic factors.

In the past 40 years after China adopted the reform and open-up policy, China’s expediting industries spatial agglomeration has resulted in severe damage to the environment. In China, the one whether the pollution haven hypothesis (PHH) is true or not is the hot issue under the research of academic circles. By establishing the mechanism model of industries spatial agglomeration and environmental pollution in this paper, we discovered upon our empirical study that China’s industrial spatial agglomeration process had apparent threshold characteristics for environmental pollution, those direct investment and scientific innovation of foreign merchants apparently improved environmental pollution, so PHH is not true in China and such conclusion provides empirical support for China’s industrial agglomeration and environmental policymaking. At the end of the paper, the policy proposals for improving environmental pollution in future are made, which have important significance for China’s high-quality economic development.

The eutrophication of water would cause the quality of the water to deteriorate and the algae to grow in large quantities. The recovery of phosphorus from sewage can not only purify the water quality, but also achieve the recycling of phosphorus. Its environmental and economic benefits are considerable. In this study, bamboo was used as raw material and modified with MgCl2 solution to prepare Mg-loaded biochar from bamboo (Mg@B). The adsorption experiments of phosphorus in solution by Mg@B were carried out. The adsorption kinetics of phosphorus by Mg@B was depicted by pseudo-first order kinetic and pseudo-second order kinetic models. The results showed that the surface of Mg@B is covered with the compound of Mg(OH)2. The adsorption process fits well with the pseudo-second order kinetics equation. The predominant process is chemisorption, which involves a sharing of electrons between the adsorbate and the surface of the adsorbent. The factor limiting the rate of reaction is primarily the number of surface-active sites of the adsorbent. The mechanism of Mg@B adsorbing phosphate ions in solution has physical adsorption, electrostatic adsorption and chemical precipitation.

Metal contamination of sediment of Ganges River (Northwestern Bangladesh) and its possible health risk to the local people were evaluated at four different sites during three seasons (summer, monsoon, winter) in the year 2016. Followed by wet digestion, the samples were analysed by Flame Atomic Absorption Spectrophotometer. Mean concentration of Cr, Pb, Ni, Cd, Mn, As, Cu and Zn were 9.31, 6.43, 0.19, 1.90, 61.66, 0.65, 9.33 and 16.14 mg/kg, respectively. According to metal indices (contamination factor, contamination degree and pollution load index), the sediment was low to moderately contaminated with the studied metals, while human health risk assessment indicated unacceptable risk (hazard index (HI) values > 1) for non-carcinogenic adverse health effect. Therefore, the sediment of the river was not contaminated enough to prevail high risk on ecological health of river and to pose health risk on local people, but regular practice of discharging contaminants can somehow worsen the river quality in the coming years.

Weight loss method was used to assess the inhibition of mild steel corrosion in 1M HCl solution with aqueous extract of Ziziphus jujuba leaves at 303 to 333K temperatures. It was found that Ziziphus jujuba leaves extract retarded the dissolution of mild steel in 1M HCl solution. The inhibition efficiency increases with a rise in the concentration of extract and decreases with increase in temperature. Maximum 88.54% inhibition efficiency was observed at 303 K and 8% (v/v) composition of the extract. Adsorption of extract at mild steel surface follows Langmuir adsorption isotherm. Values of Gibbs free energy, variation in inhibition energy with temperature and with activation energy values trend proposed the physisorption. Negative values of Gibbs energy propose the spontaneous process of inhibition process in the extract at studied temperatures.

The South-to-North Water Diversion Project in China is an important measure to promote the ecological civilization construction in the receiving areas. Since the operation of the east and middle routes, the comprehensive benefits are more and more remarkable. It is very significant to quantitatively evaluate the comprehensive benefits of the South-to-North Water Diversion Project. The idea of quantitative evaluation by the improved degree of the carrying capacity of regional water environment after water diversion is put forward in this paper. On the basis, combining with variable fuzzy set and cloud theory, a new comprehensive assessment model is established. According to the evaluation index system of water environmental carrying capacity and the index values of research area, the linear difference function value is generated randomly by triangular forward cloud generator, and then the variable fuzzy comprehensive evaluation is carried out. Taking Haihe River Basin and Beijing City as typical research areas respectively, the comprehensive benefits of water supply from the diversion project in 2030 are analysed. The comprehensive evaluation method with variable cloud model considers both “good” and “bad” aspects and considers both randomness and fuzziness. Results show that the model is feasible and efficient. It is worth popularizing and applying.

To ensure that injection water quality reaches the standard, oil field sewage stations adopt a continuous sludge dredging process to reduce the content of suspended solids and sand. A large amount of highwater- content oily sludge is produced, which results in increased costs of transportation and subsequent harmless treatment. Therefore, a sludge reduction treatment is necessary. A set of centrifugal reduction processes for oily sludge was designed in this study, with the horizontal screw centrifuge as the key piece of equipment. In the laboratory, CPAM flocculant was screened. In the field test, the effects of four factors rotational speed, differential speed, the feeding quantity of sludge, and flocculant dosage on the reduction effect were determined. The results show that when the rotational speed is higher, the differential speed is lower, and the feeding quantity of sludge remains lower, and the flocculant dosage remains higher, after treatment, the water content of the sludge is lower and the solid content of the sludge is higher. The optimal parameters of the centrifugal reduction process were determined using an orthogonal experimental design as follows: rotational speed 2,607 rpm, differential speed 8 rpm, the feeding quantity of sludge 7 m3/h, and flocculant dosage 100 g/m3. After treatment, the average water content of the sludge decreased from 92.75% to 56.57%, and the average solid content of the sludge increased from 2.30% to 36.72%. The split ratio of the water-outlet and sludge-outlet was in the range of 8.71:1 to 12.57:1, and the corresponding sludge reduction ratio was 89.70% to 92.63%, confirming successful sludge reduction.