The purpose of this study was to evaluate the concentrations of potentially toxic elements in the Suches river using standardized geochemical indices and to identify the main sources of contamination in the section from the Suches lagoon up to 33.8 km downstream of the effluent river, in the district of Cojata, Puno, Peru. The concentration of Al, Ba, Co, Fe, M, Ni, P, V and Zn in sediments of the Suches river was determined by means of mass spectrometry from October 2019 to February 2020. The values of Co, Fe, Mn, Ni, P and Zn exceeded the base values of contamination according to the general geological references while Al, Ba and V, did not surpass them. The contamination factor showed that the elements Co and Ni revealed a very high level of contamination, while the Zn, a considerable level. The area has an average pollution load index value of 2.24, indicating moderate general pollution. The elements Co, Ni, Al and Zn were within the moderate and extreme classification according to the pollution index. The Spearman's correlation analysis allowed determining the association between Al, Fe, Mn, P and V, which share a natural origin and the accumulation of these elements is due to the effects of weathering and soil erosion. The evaluation of the contamination indices and the correlation confirm that Cobalt, Nickel and Zinc are toxic elements associated with gold mining and agricultural activities.

This study utilized kinetic models to study the treatment efficiencies of a laboratory-scale up-flow biological aerated filters reactor (UBAF). The treatment efficiency of a model reactor was studied using different operating conditions of the hydraulic retention times, organic loading rates, and kinetic parameters. As a result of the calculations, the second-order and modified Stover/Kincannon models are appropriate. The substrate removal rate constant K2(S) was 1.7 per day for the reactor, with a correlation coefficient of 0.9979. Utilizing the modified Stover/Kincannon model, the coefficient of the determined concentration was 0.9987; 0.9265; and 0.9685 for Chemical oxygen demand (COD); ammonium nitrogen (NH4+-N); and Total Nitrogen (TN), respectively. The calculation of the saturation value constants and maximum utilization rate for Chemical oxygen demand (COD); ammonium nitrogen (NH4+-N); and Total Nitrogen (TN) was performed using the modified Stover-Kincannon model were 178.57 and 201.80 for COD; 1.876 and 4.6 for NH4 +-N; 3.823 and 6.644 for TN, respectively. It is possible to determine the kinetic parameter for removing COD, NH4+-N, and TN from wastewater by using the modified Stover-Kincannon model.

Activated carbon was prepared from corn cob agricultural waste with different impregnation ratios and pyrolysis times. The optimal adsorbent prepared using at 4:1 ZnCl2:corn cob char ratio at a temperature of 800 °C for 180 min provided the maximum Brunauer-Emmett-Teller (BET) surface area, total pore volume and average pore width, with values of 912.47 m2/g, 0.52 cm3/g and 22.61 Å, respectively. ZnCl2 was effective in creating well-developed pores on the surface of the activated carbon. The removal efficiency and adsorption capacity of the colour and the chemical oxygen demand (COD) of the biologically pre-treated leachate were examined utilizing the best corn cob activated carbon (CCAC) with varying CCAC dosages, contact times and initial pH values. The greatest colour and COD removal effectiveness were 88.6±0.2% and 83.7±0.4%, respectively, at the optimum CCAC dosage of 12 g for 40 min with an initial pH value of 10. In addition, maximum adsorption capacities were achieved for colour and COD of 10.3±0.02 mg/g and 12.6±0.05 mg/g, respectively, under the same conditions. The kinetics of colour and COD adsorption fitted very well with pseudo-second-order kinetic model. The CCAC performs well as an adsorbent for removing colour and COD in biologically pre-treated leachate.

In this study, the purpose was to investigate the histopathological, genotoxic effect, oxidative stress and cell death due to Metronidazole (MTZ), which is a 5-nitroimidazole compound used widely for the treatment of anaerobic organism infections in fish and humans on gill and liver tissues of Oncorhynchus mykiss.Trout fishes were exposed to 5, 10, and 20 mg/L of MTZ in the aquariums for 2, 4 and 8 days. Staining technics namely H&E, NOS immunohistochemistry, and TUNEL were performed to determine histopathological changes, oxidative damage and apoptosis. Additionally, smear preparations were also prepared from gill blood for genotoxic evaluations. The organ damage started in the 2nd day with 5 mg/L MTZ application and effects increased per duration and dose-dependent manner. It was observed that the gills had the primary and secondary lamellae lengths, with formation of clavate lamellae, fusion in secondary lamellae, separation of epithelium and aneurysm. Regional necrosis, vacuolization of hepatocytes, pycnotic nucleus, enlarged sinusoids were also determined in the liver. NOS immunoreactivity increased with the inducible immunoreactivity (iNOS) that was more prominent when compared to the endothelial immunoreactivity (eNOS). Apoptotic immunoreactivity was higher in the 10 mg 8th day experimental group at liver and gills, and was lower 20 mg 8th day experimental group. When the gills and liver compared with each other, in all doses, immunoreactivity was lower in gills, compared with liver. Genotoxic examinations showed that both number of micronucleated erythrocytes and nuclei abnormalities were higher in MTZ-treated groups.

During the past years, air quality has become an important global issue, due to its impact on people's lives and the environment, and has caused severe problems for humans. As a prevention to effectively control air pollution, forecasting models have been developed as a base for decision-makers and urban managers during the past decades. In general, these methods can be divided into three classes: statistical methods, machine learning methods and hybrid methods. This study's primary intent is to supply an overview of air pollution prediction techniques in urban areas and their advantages and disadvantages. A comparison has also been made between the methods in terms of error assessment and the use of geospatial information systems (GIS). In addition, several approaches were applied to actual data, and the findings were compared to those acquired from previous published literatures. The results showed that forecasting using machine learning and hybrid methods has provided better results. It has also been demonstrated that GIS can improve the results of the forecasting methods.

The current research study the comprehensive health and environmental hazard levels of Particulate matters originating from natural radionuclides sources collected from different Qassim region locations, Saudi Arabia. Activity concentration for 226Ra, 232Th, and 40K was assessed using a Sodium Iodide detector. Gamma-ray parameters as the Radium equivalent, Gamma level index, absorbed dose, annual effective dose, and lifetime risk were measured to predict the growth of radiological dangers. The average activity concentration for 226Ra, 232Th, and 40K is 35±0.06, 32.6±0.4, and 294.99±1.31 Bq/kg. Ra(eq) ranges from38.3 to 143.1 with an average of 104.37 Bq/kg, absorbed dose ranges from 18 to 66.49 with an average of 48.18 nGy/h, and annual effective dose ranges from 22.09 to 81.58 with an average of 59.11 μSv/y. The relative contribution was 26%, 33%, and 41% for 40K, 226Ra, and 232Th, respectively. The obtained results do not cause apprehensions from the radiation population compatible with permissible public limits. The obtained database helps the investigators follow the future pollution exchange due to Scientific progress in the use of radioactive materials.

The optimization of nickel ion (Ni2+) removal in aqueous solutions with various factors (initial Ni concentration, solution pH, adsorbent dosage, contact time), as affected by raw cow bone (RBO) and its biochar (bone char: BC; produced by pyrolysis processes at 500 °C and a residence time of 4 hours) as adsorbents was investigated by a three-level Box–Behnken model (BBM) under response surface methodology (RSM). A total of 29 experimental runs were set for each adsorbent, and the experimental data were fitted to the empirical model. To understand the Ni2+ adsorption processes better, the properties of RBO and BC were characterized using Fe-SEM, FT-IR, BET, XRD, and CHNS elemental analysis techniques. The BC characteristics showed that pyrolysis increased the specific surface area (by 100 times) and phosphate functional groups, but decreased the carbonate functional groups, and yielded a more irregular and rougher morphological surface compared to RBO. Based on BC's superior ion exchange mechanisms and physical electrostatic adsorption compared to RBO, the removal efficiency of Ni2+ by BC was higher in aqueous solutions. The numerical optimization of BBM revealed that the optimum removal by BC (82.56%) was obtained at an initial Ni2+ concentration of 30.79 mg L−1, pH of 6.99, adsorbent dose of 4.87 g L−1, and contact time of 57.82 min, with the desirability of "1". BC can be effectively used for Ni removal from Ni-contaminated aqueous solutions; still, the application of modification methods (e.g., physical and chemical activation) may be necessary to help remove more Ni2+ by BC.

A mathematical model is presented to simulate the photocatalytic degradation of terbuthylazine in a continuous stirred tank reactor. The flow field is described by the continuity equation and the momentum equation. An advection-diffusion-reaction equation is used to simulate the transport of terbuthylazine.  The chemical reactions take place on the inner wall surface coated with the catalyst, which is described by a third-kind boundary condition.  A transient differential equation is used to describe the variation of inlet concentration with time. All governing equations are solved using the commercial computational fluid software ANSYS Fluent. The simulation results agree with the experimental data at different temperatures and different flow rates. The radial distribution of terbuthylazine in the reactor is discussed in detail. The velocity depicts a parabolic curve with a maximum velocity of  0.0005 m s-1, 0.001 m s-1, 0.00022 m s-1 and 0.0032 m s-1 for 50 mL min-1, 100 mL min-1, 200 mL min-1, and 300 mL min-1, respectively. At the flow rate of 300 mL min-1, concentration of terbuthylazine decreases from 3.6 mg dm-3 to 0.8 mg dm-3 whereas concentration of cyanuric acid increases from 0.05 mg dm-3 to 0.28 mg dm-3. It shows that the radial effect of velocity and concentration should be taken into account. The mathematical model used in this study is suitable for simulating the photocatalytic degradation process of terbuthylazine in continuous stirred tank reactors.

This study was conducted in order to assess the level of heavy metals in the water, soil, and tissues of Pomacea canaliculata from Lake Dakong Napo, Esperanza, Philippines as well as identify the histopathological alterations in the gonads and muscles of the snail. Heavy metals were detected using Atomic Absorption Spectrometry and slides for histological studies were prepared using histological routine procedure. Results revealed that in sediments Cr (174.67±62 mg/L) and Ni (269.33±17.56 mg/L) were above from the recommended safe limits of the international standards, US EPA (≤25) and FAO (≤50) while concentrations of Pb (16.35± 0.58 mg/L), Cd (5±1.42 mg/L), and Cr (1±0 mg/L) in water were above from the recommended safe limits of the national standards, DAO (≤0.05; ≤0.01; ≤0.05). These heavy metals were below the permissible limits in the gonads and muscles of P. canaliculata however, alterations in the tissues of the snail are evident suggesting that these heavy metals and other environmental stressors are negatively affecting the organisms inhabiting the lake.

This article is devoted to the study of the impact of the development of the Lomonosov diamond deposit on the pollution of watercourses with trace metals. The high water cut of the exposed rock strata and the presence of groundwater require the constant pumping of wastewater into the filtration fields, and then to the nearby river. This work shows a significant contribution of discharge processes and drainage waters to the trace metal contents in the surface waters of the Zolotitsa river; an increase in the concentrations of Mg, Sr, Zn, Cu, Cd, As , and Se was noted. The seasonal variations of physicochemical parameters, the trace metal contents, as well as the total uranium and U isotope 234U, 238U, and 235U were analysed. Calculations of water quality indices (HMEI, HMPI, and HMTL) and public health risks (HI and CR) revealed a high level of pollution of certain sections of watercourses. Radiological studies of polluted rivers in the area showed a satisfactory situation. The results of this study can provide a basis for the subsequent monitoring of the impact of anthropogenic activities on nearby watercourses in the development of diamond deposits.