Heavy metals are elements that can have toxic effects even at low concentrations. Heavy metal pollution is one of the most concerning issues at the global level because of the health risks it causes and its negative effects on the ecosystem. Many studies have been carried out in the past years to reduce heavy metal emissions, pollution, and their effects on health. In this context, a scientometric study was conducted to show how this topic has developed academically and to identify effective studies in the field of heavy metal removals for water. When the Web of Science (WoS) database is searched, a total of 22,911 articles were collected based on the heavy metal removals for water subjects, and then, articles were sorted and the top 100 most cited articles were determined. By determining the top 100 most cited articles on this subject, bibliometric analysis has been carried out by covering co-occurrence, co-citation analysis, cluster analysis, and much more. When these top 100 most cited articles were examined, it was seen that review articles were in the majority (59%), and there were more studies in environmental sciences, engineering environmental, engineering chemical, biotechnology applied microbiology categories. It has been observed that most of these most cited articles were published between 2007 and 2012, and the citations given to these 100 articles increased almost linearly since 2007. In addition, it has been determined that China ranks first in this regard with 23 articles and 21,137 citations. The working network between countries, institutes/universities has been revealed. It was determined that the words adsorption, heavy metals, and waste were used the most among the keywords. This study is expected to lay the groundwork for future discussions on the subject. Our analysis provides information on technology and informs decision-makers and researchers about the value of new and existing technologies and future opportunities.

Although West African nations are flourishing economically of late, they still have environmental issues due to the high rate of emissions in the bloc. Despite the worsening environmental condition, there have been limited studies on the causal agents of this situation in the region. Therefore, drawing strength from the United Nations’ Sustainable Development Goals (SDGs) and their targeted impacts of 2030, this study explored the nexus between financial development and environmental sustainability in West Africa (WA) for the period 1990 to 2016. The cross-sectional autoregressive distributed lag (CS-ARDL) estimator alongside the cross-sectionally augmented distributed lag (CS-DL) and the cross-sectional augmented error correction (CAEC) estimators were engaged to examine the elastic effects of the explanatory variables on the explained variable and from the results, financial development was harmful to environmental sustainability in WA through high carbon emissions. Also, control variables foreign direct investments, energy consumption, industrialization, and population growth were detrimental to the sustainability of the environment. On the causal connections amid the series, a unidirectional causality from financial development and population growth to carbon emissions was uncovered. Also, feedback causalities between foreign direct investments and carbon emissions, between energy consumption and the effluents of carbon, and between industrialization and environmental pollution were unraveled. Based on the findings, the study recommended among others that the countries should integrate environmental welfare objectives into their financial development policies. Also, the nations should ensure that their citizens have access to energy that is affordable, reliable, sustainable, and modern (SDG 7). Finally, improvement in energy efficiency, sustainable infrastructure, and good use of resources (SDG 12) should be promoted by the nations. The above recommendations if seriously taken into consideration will help the region to combat climate change and its impacts, which is the focus of SDG 13. The main flaw of this exploration was the lack of data for some specific time periods. Therefore, in future when such data become available, similar investigations could be carried out to confirm the robustness of the study’s results.

Cyanobacterial blooms accompanied by taste and odor (T&O) compounds affect the recreational function and safe use of drinking water. Geosmin and 2-methylisoborneol (2-MIB) are the most common T&O compounds. In this study, we investigated the effect of temperature on geosmin and 2-MIB production in Dolichospermum smithii and Pseudanabaena foetida var. intermedia. More specifically, transcription of one geosmin synthase gene (geoA) and two 2-MIB synthase genes (mtf and mtc) was explored. Of the three temperatures (15, 25, and 35 °C) tested, the maximum Chl-a content was determined at 25 °C in both D. smithii and P. foetida var. intermedia. The maximum total geosmin concentration (19.82 μg/L) produced by D. smithii was detected at 25 °C. The total 2-MIB concentration (82.5 μg/L) produced by P. foetida var. intermedia was the highest at 35 °C. Besides, the lowest Chl-a content and minimum geosmin/2-MIB concentration were observed at 15 °C. There was a good positive correlation between geosmin/2-MIB concentration and Chl-a content. The expression levels of the geoA, mtf, and mtc genes at 15 °C were significantly higher than those at 25 and 35 °C. The transcription of the mtf and mtc genes in P. foetida var. intermedia was higher at 35 °C than at 25 °C. The results highlight unfavorable temperature can increase the potential of geosmin/2-MIB synthesis from the gene expression level in cyanobacteria. This study could provide basic knowledge of geosmin/2-MIB production by cyanobacteria for better understanding and management of T&O problems in drinking water.

Sodium chloride (NaCl) is commonly used as a curing/preservative agent for raw hides and skins in tanneries and is removed through a soaking process with total dissolved solids (TDS) and other organic pollutants in effluent, causing significant pollution load to the environment. Hence, the present study evaluated to apply dried neem leaf powder (DNL) as an additive to reduce the usage of salt in skin processing and preservation. To make certain of DNL antimicrobial properties, solvent extracts were performed against proteolytic bacteria isolated from raw skins. Initial characterization of DNL revealed the presence of bioactive compounds nimbolide and dehydro salannol and acetone extract with 16.9-mm, 10-mm and 8-mm zone of inhibition against Salmonella sp., E. coli sp. and Bacillus sp. identified using phenotypic conventional biochemical screening method. Further, skin curing experiments were carried out using four different treatments of DNL (10% 15%, 20% and 25% w/w) along with 15% w/w of conventional salt to obtain an optimum concentration for pilot-scale studies. Thus, the application of optimal DNL (15%) and salt (15%) resulted in no physical changes such as smell and hair slip and was taken for further studies for hydroxyproline activity, pollution load and organoleptic properties along compared with control 40% salt. DNL-aided salt less preservation of freshly flayed goat skins at ambient condition showed no hair slip or putrefaction during the preservation period with significant reduction of TDS (86%) and chloride (71%) in soak liquors compared to conventional salt preservation and enhanced organic load requiring additional treatment. However, the application of the organoleptic, physical and hydrothermal properties of resulting leathers produced from the DNL applied skins was on par with results of leather obtained from conventional salt. Thus, our results demonstrate DNL-aided salt less preservation method is able to reduce the amount of salt for preservation of goat skins significantly, leading to reduced salinity issues during leather processing.

Black shales are easily exposed due to human activities such as mining, road construction, and shale gas development, which results in several environmental issues including heavy metal (HM) pollution, soil erosion, and the destruction of vegetation. Mosses are widely used to monitor metal pollution in the atmosphere, but few studies on the distribution and dispersion of HMs in the rock–soil–moss system are available. Here, mosses (Pohlia flexuosa Harv. in Hook), growing soils, and corresponding parent rocks were collected from black shale areas. After appropriate pretreatment, samples were analyzed for multiple elemental concentrations by ICP-AES and ICP-MS. The results show that black shale parent rocks have elevated HM concentration and act as a source of multiple metals. The overlying soil significantly inherits and accumulates heavy metals released from black shale. Significant positive correlations between HMs in P. flexuosa and the growing soils indicate that HMs are mainly originating from geological source rather than atmospheric deposition. Differential accumulation of HMs is observed between rhizoids and stems in our study. Moreover, P. flexuosa is able to cope with high concentrations of toxic metals without any visible negative effect on its growth and development. Finally, the bioconcentration factor (BCF) for all the HMs in P. flexuosa is less than 1, indicating that it has a tolerance and exclusion mechanism for these metals, especially for the non-essential elements As and Pb. Therefore, the luxuriant and spontaneous growth of P. flexuosa could be used as a phytostabilization pioneer plant in the black shale outcrop where vascular plants are rare.

The motivation of this fundamental research is to reveal the response of ecosystem services to land use change and to support the sustainable development of ecology, economy, and society. Considering the fragile eco-environment, intensive man-land relationship and the world-famous production base of Moutai liquor in China, we select Chishui River Basin (CRB) as the research region. In this study, the InVEST model is used to evaluate the impact of land use change on the spatial pattern of four ecosystem services including water yield, soil retention, carbon storage, and nitrogen export. Meanwhile, the spatial differentiation characteristics, service level, and trade-off using Pearson correlation analysis of each ecosystem service from 2000 to 2020 are explored. The results show the following: (1) The forest increased, while the grassland and cultivated decreased. Especially, the developed has increased greatly from [Formula: see text] to [Formula: see text]. (2) Each ecosystem service has spatio-temporal heterogeneity. The water yield and nitrogen export decreased, while soil retention and carbon storage showed an upward trend. (3) There are great differences in the level of ecosystem services among different land use types. The soil retention and carbon storage of forest are the highest, and the water yield of developed is the highest. (4) There are trade-offs and synergies among ecosystem services, such as the trade-off between water yield and soil retention is increasing, the synergetic relationship between water yield and nitrogen export is decreased. This is important evidence that the forest plays a major role in providing ecosystem services, and the improvement of watershed ecological services generally benefits from the implementation of ecological governance projects in recent years. However, it is worth noting that the frequent changes in land use and the intensification of urbanization have also brought potential risks to the local ecology. Therefore, all our preliminary results throw light on the nature of the impact of land use change on ecology and the trade-off relationship of ecosystem services, which is conducive to scientific protection of watershed ecological environment and the formulation of reasonable land use planning policies.

The microorganisms and allelochemicals in Pontederia cordata planting water may have a synergistic inhibitory effect on algae. To study this synergy, an algae-inhibiting organism was isolated and identified, and its growth and feeding characteristics were studied. The organism was identified as Poterioochromonas malhamensis yzs924 based on both its morphology and molecular barcoding employing 18S rDNA gene sequences.The growth and feeding of P. malhamensis were affected by environmental factors and the state of its prey. (1) P. malhamensis is a mixotrophic flagellate. Its heterotrophic growth was the fastest in a wheat grain medium, and its growth rate in this study reached 2.5 day⁻¹. (2) Within a short period of time (2 days), P. malhamensis growth was slower under continuous dark conditions than under alternating light and dark conditions, but it fed on Microcystis aeruginosa more rapidly under dark conditions. (3) High pH was disadvantageous to the growth and grazing of P. malhamensis. When the pH was kept stable at 9, P. malhamensis could not grow continuously. (4) When the initial density of M. aeruginosa was 5 × 10⁷ cells/mL or is in a period of decline, P. malhamensis could not remove all M. aeruginosa. The combined use of P. malhamensis and allelochemicals may represent a method of M. aeruginosa control, but this approach requires further research.

Synthesis and characterization of dual functioning material is an effective approach for the promotion of organic pollutant degradation through adsorption as well as photocatalysis. Herein, graphene oxide was modified by the addition of barium nitrate and iron to construct a smooth sheet-like structure (BaFe₂O₄/rGO) for the removal of chlorhexidine digluconate (CHD). Compared with GO (75.69%—UV light; 88.17%—visible light), BaFe₂O₄/rGO showed significant adsorption-photocatalysis effect under visible light (93.95%) than that under UV light (78.17%). The introduction of barium nitrate and iron into graphene oxide leads to a smooth porous structure with increased surface area (93.66 m² g⁻¹), which resulted in a large number of adsorption active sites and great photocatalytic activity with efficient charge separation. Although catalysts did not mineralize CHD completely, but the parent compound mineralized to some extent, which was confirmed by the TOC measurement and UV₂₅₄ absorbance variation. In addition, toxicity of degraded products was analysed by bacterial susceptibility test on Bacillus cereus DPAML065, suggesting that nontoxic by-products of CHD were formed, which leads to their safe disposal. Based on the identified transformed products, the possible degradation pathway was proposed. Batch studies demonstrated that BaFe₂O₄/rGO is highly photoactive based on reaction rate constant (R² = 0.984), where the kinetics data were well-fitted using the pseudo-first order. Moreover, efficiency of catalysts was examined under solar light to achieve the sustainability.

Cyanobacterial blooms affect biotic interactions in aquatic ecosystems, including those involving heterotrophic bacteria. Ultra-small microbial communities are found in both surface water and groundwater and include diverse heterotrophic bacteria. Although the taxonomic composition of these communities has been described in some environments, the involvement of these small cells in the fate of environmentally relevant molecules has not been investigated. Here, we aimed to test if small-sized microbial fractions from a polluted urban lagoon were able to degrade the cyanotoxin microcystin (MC). We obtained cells after filtration through 0.45 as well as 0.22 μm membranes and characterized the morphology and taxonomic composition of bacteria before and after incubation with and without microcystin-LR (MC-LR). Communities from different size fractions (< 0.22 and < 0.45 μm) were able to remove the dissolved MC-LR. The originally small-sized cells grew during incubation, as shown by transmission electron microscopy, and changed in both cell size and morphology. The analysis of 16S rDNA sequences revealed that communities originated from < 0.22 and < 0.45 μm fractions diverged in taxonomic composition although they shared certain bacterial taxa. The presence of MC-LR shifted the structure of < 0.45 μm communities in comparison to those maintained without toxin. Actinobacteria was initially dominant and after incubation with MC-LR Proteobacteria predominated. There was a clear enhancement of taxa already known to degrade MC-LR such as Methylophilaceae. Small-sized bacteria constitute a diverse and underestimated fraction of microbial communities, which participate in the dynamics of MC-LR in natural environments.

This paper constructs the calculation method of total factor efficiency and low-carbon technology progress indicators based on the undesirable SBM model and Malmquist-Luenberger productivity index model, and this empirically analyzes the relationship between green credit, environmental regulation, and total factor efficiency or low-carbon technology progress by using the panel data of 30 regions in China from 2009 to 2018. The study results show that the carbon emission efficiency evaluation results of each region vary greatly; the largest gap reaches 400%. China’s overall carbon emission efficiency has 35–40% room for improvement, and it is increasing year by year at the rate of 0.96% mainly depends on the improvement of technological progress. The improvement of China’s carbon emission efficiency should focus on the central and western areas. The relationship between the green credit level and the total factor efficiency and low-carbon technical progress is significant “U-shaped” curve, while the relationship between the environmental regulation intensity and the total factor efficiency and low-carbon technical progress is significant “inverted U-shaped” curve. The proportion of tertiary industry, ownership structure and average scale of industrial enterprises have significant positive, negative and negative effects on regional total factor efficiency and low-carbon technical progress.