A hybrid system integrated by anaerobic filter–baffled subsurface horizontal constructed wetland (AFwet) was studied for treating polluted channel water, varying the hydraulic retention time (HRT) from 8 to 2 days. A conventional wetland (CW) and baffled conventional wetland (bCW) were used as control systems. The higher COD and ammonium nitrogen removal efficiencies were achieved at HRT of 8 days, of which the AFwet system was the best. At HRT of 2 days, COD removals for CW, bCW, and AFwet system were 54.22%, 72.96%, and 80.68%, respectively, whereas the ammonium removals were 34.16%, 50.07%, and 95.97%, correspondingly. The experimental results showed that the anaerobic filter intensified the ammonium removal, achieving removal efficiencies above 90%. The smallest footprint of 2.2 m²/PE (population equivalent) was obtained at hydraulic loading rate (HLR) of 0.14 m²/m³ day and organic loading rate (OLR) of 36.2 g COD/m² day. Nowadays, footprint and pollutant removal are significant indicators for the choice of constructed wetland.

The strength and shape of the dose–response relationship between different types of noise and myocardial infarction (MI) remain unclear. Therefore, we aimed to summarize the evidence of the association between various types of noise and MI incidence and mortality through a dose–response meta-analysis. We performed a systematic search of the PubMed, Embase, and Web of Science databases up to December 19, 2021. The generalized least-squares method and restricted cubic splines were used to assess the potential linear and nonlinear dose–response relationships between noise exposure and the risk of MI events. Twenty observational studies with 34 reports met the eligibility criteria. In the linear models, the pooled relative risk and corresponding 95% confidence interval (CI) for MI incidence was 1.04 (95% CI: 1.02 − 1.05), and the MI mortality was 1.02 (95% CI: 1.02 − 1.03) for each 10 dB(A) increase in noise exposure. In addition, we observed an approximately J-shaped dose–response relationship between noise and MI mortality (Pₙₒₙₗᵢₙₑₐᵣᵢₜy = 0.0037), whereas the threshold for the statistical impact of noise on MI mortality may be 42 dB(A). Our findings support the notion that various types of noise exposure have a positive dose–response relationship with the risk of MI incidence and mortality.

The present study verified the potential of volcanic rock powder residues originating from the extraction of semi-precious rocks in the state of Rio Grande do Sul, Brazil, as precursors or adsorbents for dyes and metallic ion removal from water. In this way, it is possible to add value and give an adequate destination to this waste. Volcanic rock powder residues from Ametista do Sul (AME) and Nova Prata (NP) were the starting materials. These were used naturally or submitted to the alkaline activation process at 60 °C and alkaline fusion at 550 °C. The analysis of the starting samples by X-ray fluorescence (XRF) revealed that they are mainly composed of aluminum, calcium, iron, and silicon oxides, which corroborates the presence of numerous crystalline phases observed in the X-ray diffraction spectra (XRD). Moreover, by XRD analysis of the synthesized samples, alkaline fusion proved to be more efficient in the dissolution of crystalline phases and consequently in the formation of the amorphous phase (more reactive). Furthermore, the adsorption tests with acid green and acid red dyes and Ag⁺, Co²⁺, and Cu²⁺ ions indicated the viability of using residual volcanic rock powder as raw material for the production of adsorbents functionalized with sodium hydroxide, being that the samples synthesized by alkaline fusion showed better results of removal and adsorption capacity for all the contaminants used in the study.

As China’s economy continues to grow, more and more attention is being paid to environmental pollution issues, including haze pollution, which is the most prominent of the air problems. In order to alleviate the haze pollution problem while ensuring the normal operation of the economy, the government has adopted an environmental regulation policy along with the introduction of foreign direct investment. This study uses a fixed effects model and two-stage least squares to examine the correlation of foreign direct investment and environmental regulation to the haze pollution level by using the Chinese provincial panel data from 2008 to 2019. We found a positive interaction between the foreign direct investment and environmental regulation, where a high-quality investment promotes the haze reduction, and the environmental regulation can enhance this effect. The results approve the possibilities that China can bring the merit investment and reduce its air pollution simultaneously, but how to balance the interaction between environmental regulation and the investment needs to draw attention.

Stormwater ponds can provide flood protection and efficiently treat stormwater using sedimentation. As the ponds also host aquatic biota and attract wildlife, there is a growing concern that the sediment bound pollutants negatively affect aquatic organisms and the surrounding ecosystem. In this study, we used three methods to assess the accumulation and the potential ecological risk of 13 different heavy metals and metalloids (e.g. trace elements) including both elements that are frequently monitored and some which are rarely monitored in sediment from 5 stormwater ponds located within catchments with predominately industrial activities. Ecological risk for organisms in the older ponds was observed for both commonly (e.g. Cd, Cu, Zn) and seldom (e.g. Ag, Sb) monitored trace elements. The 3 methods ranked the degree of contamination similarly. We show that methods usually used for sediment quality assessment in aquatic ecosystems can also be used for screening the potential risk of other trace elements in stormwater ponds and may consequently be useful in stormwater monitoring and management. Our study also highlights the importance of establishing background conditions when conducting ecological risk assessment of sediment in stormwater ponds.

Herein, we conducted a study of the Zhangsanxi karst groundwater system in Zhangjiajie, Hunan Province, China, and used the results to develop a method for identifying the aquifer medium and its structural characteristics. To begin, rainfall, underground river flow dynamics, and groundwater level dynamics in the Zhangsanxi karst groundwater system were subjected to high-resolution monitoring to elucidate the groundwater system’s rainfall-hydrological response characteristics under varying rainfall amounts and intensities. Next, an exponential attenuation curve was employed to analyze how the law of attenuation applies to underground river discharge and groundwater level during a typical rainfall event. Finally, we determined the degree of karst development at different depths, so the data can serve as a reference for local decision makers regarding karst water disaster prevention and water resource utilization. The results show that the flow response lag time in the karst groundwater system depicts good correlation with the rainfall amount but is also affected by the rainfall intensity. Thus, under conditions of identical rainfall, increasing rainfall intensity corresponds to a progressively shorter underground river flow lag time. The area’s rainfall can be divided into four types, based on its concentration and intensity characteristics. The underground river flow generally has no evident response to type I rainfall, while the flow response lag time to types II III and IV rainfall is approximately 110, 60, and 40 h, respectively. Furthermore, the Zhangsanxi karst system’s water-bearing medium is dominated by karst fissures and pores, which account for about 2/3 of its open space. Large karst conduits and caves account for the remaining 1/3. The degree of karst development in this system depicts evident depth variation but, overall, tends to increase as a function of burial depth.Responsible editor: Xianliang Yi.

The presented study sheds light on the applicability of inductively coupled plasma optical emission spectrometry (ICP-OES) for the multielement analysis of naturally obtained water. The technique mainly focused on the determination of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) which are considered to be toxic metals and have deteriorating health impacts. The water samples were collected from Lake Iripixi (1°46′00″S and 55°51′30″W) located in the municipality of Oriximiná, PA, Brazil. The validation characteristics of the method including the limit of detection (LOD) and limit of quantification (LOQ) were also studied which were obtained in a satisfactory range for all heavy metals. The physicochemical characteristics of the soil like dissolved oxygen (DO), pH, conductivity, and total dissolved solids (TDS) were also determined. The most suitable emission wavelengths were selected for the analysis of each toxic metal. The LOD and LOQ results showed that the method is suitable, simple, sensitive, and practical for the analysis of toxic metals.

This study aimed to evaluate the effects of untreated pig manure from diets incorporating growth-promoting supplements (antibiotics and Zn oxide) on the survival and reproduction of Eisenia andrei earthworms. The tested manures were obtained from four different groups of pigs fed with four different diets: CS, a diet based on corn and soymeal; TR, a diet based on corn, soymeal, and ground wheat (15%); CSa, a diet based on corn and soymeal + 100 ppm of doxycycline + 50 ppm of colistin + 2500 ppm of Zn oxide; and TRa, a diet based on corn, soymeal, and ground wheat (15%) + 100 ppm of doxycycline + 50 ppm of colistin + 2500 ppm of Zn oxide. The study used two soils representative of the Southern region of Brazil (Oxisol and Entisol). In general, there were no significant differences between the different manures tested in each soil. However, there were differences in the toxicity manure on E. andrei between the soils, and the magnitude of this effect was dependent on the applied dose. In Oxisol, LC₅₀ values were higher than 80 m³ ha⁻¹, and EC₅₀ varied from 9 to 27 m³ ha⁻¹. In Entisol, the LC₅₀ values were below the lowest dose tested (< 25 m³ ha⁻¹), and EC₅₀ remained around 5 m³ ha⁻¹. It may be possible that the effects observed were attributed to an excess of nitrogen, copper, and zinc, promoted by the addition of the untreated manure and how these factors interacted with soil type.

An effort is being conducted to enhance some characteristics of self-compacted concrete (SCC) and clean the environment through the addition of waste plastic fibers resulting from the cuts of waste medical radiology. A number of tests were carried out to examine the impact of waste medical radiology (WMR) fiber additions with various aspect ratios and various percentages on SCC characteristics. Thus, various SCC mixes were designed at a constant water-to-binder ratio of 0.33 and 550 kg/m³ of binder content. The four groups of WMR fiber content were specified with different aspect ratios of (0, 40, 50, and 60) with various ratios of (1%, 1.25, and 1.5%) by volume of concrete. The workability characteristics of SCC mixes were determined by fresh density, segregation resistance, L-box height ratio, T50 slump with V-funnel flow time, and slump flow diameter. Also, the measurement of thermal conductivity, compressive, flexural, and splitting tensile strengths were performed at 28 days for SCC mixtures. The findings revealed that WMR fibers have a negative impact on the fresh characteristics of SCC except for segregation resistance, which improved. However, the results of splitting tensile and compressive strengths were enhanced at 1% WMR fiber content with various aspect ratios then decreased. However, all results of flexural strength were reduced in comparison with the control mixture excluding samples containing 1% WMR fibers with an aspect ratio of 50 which showed a higher result. The outcomes of thermal conductivity were reduced with the usage of various WMR fiber percentages and various aspect ratios in comparison with the control mixture, and the best result was obtained at 1.25% WMR fiber with an aspect ratio of 50.

Understanding of the sources and processes involved in the heavy metal accumulation in river sediments is important for measuring the risks associated with human exposure. Hence, an integrated modeling approach was designed to study the linkage between landscape-related natural and anthropogenic features and high arsenic levels at the outlet of six catchments on the Ghareh-Ajagh River, central Iran. Sediment arsenic levels were measured in 8 months from October 2018 to November 2019 when the river sediment and water conditions were stable and ranged from 16.3 to 78.5 mg/kg. Monthly catchment-level agricultural areas were extracted from Landsat 8-OLI images. Predictive variables included NDVI values; area and spatial patterns of agriculture measured using four landscape metrics of NP, PD, MPS, and ENN; length and slope of the streams extended from main agricultural areas to the catchment outlet; and four hydrologic soil groups. The best-fitted multiple regression model (r² = 0.763, p≤ 0.05) with the Akaike information criteria of 105.07 was developed using stream length, soil group C, and area and PD of agricultural areas. Results showed that sediment arsenic levels increase with increasing quantity and density of agricultural activities that were close to the river outlet and increasing proportion of silty loam or loamy soils but are relatively less dependent on agricultural structural patterns. These insights are helpful to inform policy decisions regarding the processes involved in river contamination in central Iran.