This study used the integrated biomarker response (IBR) index approach to assess the ecological risks of heavy metals in different regions of Dianchi Lake, combined with active monitoring and passive monitoring. The contents of five heavy metals (Cu, As, Cd, Hg, and Pb) and six biomarkers (acetylcholinesterase, sodium-potassium ATPase, metallothionein, superoxide dismutase, glutathione peroxidase, and malondialdehyde) in the muscles of crucians (Carassius auratus) were measured to calculate the IBR value. The results indicate that the contents of heavy metal in the fish under active monitoring and passive monitoring were rather low and did not exceed the National Food Safety Standards of China. The IBR value of day 14 of active monitoring correlated with the heavy metal Cd content in the fish, suggesting a potential risk of Cd pollution in the aquatic environment of Dianchi Lake. The IBR values obtained for different regions of the lake on day 14 can be arranged in the following order: West S3 (9.24) > East S1 (3.97) > South S2 (2.39) > North S4 (0.36). These results suggest a potential risk of heavy metal contamination in the western part of Dianchi Lake.

The reuse of olive mill wastewater (OMW) by spreading on agricultural land is subject to a long-time debate since they supply to agricultural land both substances of undoubted positive influence on fertility and compounds that may adversely alter its chemical, physical and microbiological characteristics and/or cause negative effects on crops. In this study different amounts of OMW from 3-phases centrifugal decanter were spread in February on soil cultivated with grapevine in a research-farm located in central Italy for 11 consecutive years, with the aim to verify the long term effect on grape production, physico-chemical and microbiological characteristics of soil. In particular, the effect of the OMW spread in the largest amount (50 L m⁻²) was an increase of the weight of the grape-brunches and total grapes production and, in addition, an improvement of the soil characteristics due to the increase of the content of the organic reducing substances with humic-like properties. Moreover, it was also ascertained that in the short-medium period (2–8 months) the respiratory activity of the micro-organisms of the soil parcels, treated with different amount of OMW, was higher than that of the soil control parcels. The results obtained demonstrated that the controlled spreading of OMW helps to increase both the grapes crop and the fertility of the soil, recycling the organic matter and mineral nutrients, in this way allowing to reduce, or avoid, the use of chemical fertilisers.

This study calculates the green investment level of each province in China and objectively estimates the provincial environmental regulation level from the perspective of the government to examine the effectiveness and impact of the government’s environmental protection policy on the environmental regulation level. The carbon emission trading pilot policy is determined through a quasi-natural experiment difference in difference model to examine the impact and assess the effectiveness of green environmental protection policies on the environmental regulation level empirically. Results show that (i) the green investment level of the carbon emission trading pilot provinces is significantly lower than that of other nonpilot provinces after 2013, and (ii) the introduction of environmental protection policies has reduced the government’s green investment level by approximately 8%. These findings confirm that environmental regulation policies play a significant role in promoting the environmental regulation level. Further mechanism analysis shows that environmental regulation policies influence this level through carbon dioxide emissions. This study provides a reference for environmental regulation policy making.

Ecosystems play critically important roles in supporting human society, while human activities seriously disturb their initial balance. Lots of researches on ecosystem services are conducted due to the increasing concern on ecological security worldwide. In order to provide valuable insights for understanding the primary performance of ecosystem services–related studies, a qualitative and quantitative analysis by using a bibliometric tool is performed in this study. Journal impact factor, CiteScore, and h-index are used for identifying influential journals, while h-index is used for recognizing productive countries/territories and institutions. Social network analysis of countries/territories and institutions is visualized, respectively, so that relationships among them can be uncovered. Citation analysis of publications and co-occurrence analysis of high-frequency keywords are also performed to explore hotspots and popular methods in this field. This study uncovers a holistic picture on the primary performance of ecosystem services–related literatures published from 1997 to 2016, including journals, countries/territories, and institutions. Results find that forest, agriculture, and wetland ecosystems attract lots of attention. Finally, major methods used for ecosystem services evaluation are identified and discussed. Research outcomes will provide valuable insights to stakeholders interested in ecosystem services.

Microplastics have become a major environmental concern globally due to their potential impact on ecosystem function. They are known to be ubiquitously present, persistent and bio-accumulative, yet there is a lack of abundance quantifications in freshwater shorelines. Furthermore, there is little understanding of combined effects of seasonality and human population density on the extent of microplastic pollution. In this study, we assessed microplastics in sediment along a subtropical reservoir shoreline across three seasons and seven sites to understand microplastic pollution dynamics along a human population gradient. Multivariable analysis was used to assess relationships among substrate embeddedness, sediment organic matter, human population density and microplastic particle densities and characteristics. Microplastic densities were relatively high during the hot–dry season (mean range 120–6417 particles kg⁻¹ dwt) whilst the hot–wet season had the lowest densities (mean range 5–94 particles kg⁻¹ dwt). Microplastic abundances were positively correlated with population density, demonstrating the direct effects of human activity on microplastic contamination. These results highlight the need to further explore microplastic distribution patterns in freshwater ecosystems in the Southern Hemisphere. Furthermore, our findings suggest particular risk for fauna during low rainfall periods through microplastic concentration effects.

In recent years, the problem of rising salinity levels in the Shatt al-Arab river in southern Iraq has been repeated, which has directly affected the living and health situation and the agricultural activity of these areas. Six sampling stations were selected along Shatt al-Arab to estimate the concentration of total dissolved solids (TDS) in the river; these stations included the following: Qurna, Labani, City Centre, Kateban, Corniche, and Sihan. In addition, three Landsat-8 satellite images which were taken at the same time as collected samples also used for detecting the salinity in the river. After processing of atmospheric correction and inserted remote sensing indices, the reflectance of water extracted from satellite images was used to express the spectral characteristics of different TDS concentrations. Correlation and regression were used to obtain accurate models for detecting the salinity depending on the spectral reflectance of Landsat 8 operational land image OLI. The results presented Pearson correlation (r) value of 0.70, 0.97, and 0.71, and correlation coefficient (R²) of 0.56, 0.94, and 0.85 between field data with spectral data of salinity index 2 (SI-2) derived from the green and blue bands of Landsat obtained in 2015, 2017, and 2018 respectively. In conclusion, remote sensing and GIS technologies coupled with spectral modeling are useful tools for providing a solution of future water resources planning and management, and also offer great undertaking as a means to improve knowledge of water quality and support water decision making.

Sulfadiazine (SDZ) was effectively removed by the heterogeneous catalytic sulfate radical (SO₄•⁻) oxidation using a novel composite material of mesoporous carbon (MC) loaded nano zero-valent iron (nZVI). Possessing larger specific area (433.3 m² g⁻¹) and high mesopores volume (2.537 cm³ g⁻¹), the composite material (nZVI/MC) was used as the activator to activate persulfate for the degradation of SDZ. The results of degradation experiments indicated that the removal efficiency of SDZ in nZVI/MC+ persulfate (PS) process reached the highest, due to good dispersing property of MC for nZVI. The removal of SDZ was further enhanced by the increase of nZVI loading as well as the nZVI/MC composite content. Quenching experiments showed that SO₄•⁻ acted a crucial role in the degradation process of SDZ. Both the FT-IR and XPS analyses showed that the FeO contents decreased after degradation reaction, which indicated the occurrence of active oxidation reaction between SO₄•⁻ and Fe²⁺ from the breakage of the Fe–O bond. The LC-MS analysis indicated that the cleavages of C–N bond in the heterocyclic ring and N–S bond were the major degradation pathway of SDZ, attributing to the attack of SO₄•⁻ and •OH. These results demonstrated that the novel nZVI/MC composite with excellent stability could be used for the effective degradation of SDZ through activating PS to produce SO₄•⁻. Graphical Abstract

Cross-linking of polymer hydrogels can be achieved by exposing the polymer to gamma radiation that induces production of polymer chain radicals resulting in cross-linking of chains. The present study was focused on fabrication of hydrogel by gamma irradiation for immobilization of bacterial cells. Hydrogels were prepared using 30 and 40% acrylamide at gamma irradiation dose of 5 kGy. Five bacterial strains BR-6, BR-14, BR-18, BR-21, and BR-26 screened for resistance to strontium were immobilized in hydrogels and evaluated for the bioremoval of strontium. Strontium content for different strains was 4.21–4.68 μg/ml after 3 days in the presence of free cells grown in 5 μg/ml strontium, while for immobilized cells, the strontium content was 3.35–3.81 μg/ml (30% acrylamide gel) and 3.46–3.99 μg/ml (40% acrylamide gel). After 10 days of incubation, the strontium content was reduced to 0.94–1.26 μg/ml (30% acrylamide gel) and 0.82–1.07 μg/ml (40% acrylamide gel), and for free cells, strontium content was 1.34–1.41 μg/ml. 72–75% bioremoval of strontium by free cells of different strains BR-6, BR-14, BR-18, BR-21, and BR-26 was observed after 10 days of incubation. 77–83% reduction in strontium content was observed in the presence of cells immobilized in 30% acrylamide, whereas higher reduction of 80–85% was observed for cells immobilized in 40% acrylamide after 10 days. At higher concentration of 10-μg/ml strontium, 62 to 71% reduction was observed with immobilized bacterial cells. Obtained results indicated that immobilized bacterial cells in hydrogels prepared by gamma irradiation were found to have significantly higher efficiency as compared to free cells for bioremoval of strontium ions.

Small-scale agriculture (SA) is regarded as unsustainability because of its low benefit. To protect traditional agricultural landscapes like terraces through SA will be difficult. However, in China, terraces are still maintained well by smallholders now. This study takes the family as a basic unit and SA in Hani terraced region as an object to explore its sustainability from the perspective of labor productivity (LP) through the questionnaire method. The findings are that peasant households work on both farm and non-farm jobs. They get a low income (3854.5 yuan RMB) from hybrid-rice-cropping and a high income (44,665.8 yuan RMB) from non-farm jobs but spend a small part of labors (34.23 person•days) in growing hybrid-rice and expended lots of labor (522 person•days) for non-farm jobs. In conclusion, LP of hybrid-rice-cropping is 1.32 times that of non-farm jobs for a household. The result shows SA in Hani terraced region has a higher return of labor investment than non-farm jobs. It is different from the common impression of the low benefit of SA and also explains why SA still continues to exist in the mountainous area in China now. However, SA in Hani terraced region also faces challenges with salary level rise of non-farm jobs and part-time farmers’ requirement for living quality improvement. In the future, promoting industrial integration development in this region to add local employment for improving farmers’ income is a feasible approach to protect terraced landscapes.

Mining industry generates large volumes of waste known as mine tailings, which contain heavy metals (HMs) that generate a risk to environmental health. Thus, remediation of HM pollution requires attention. In this study, HM bioaccumulation, genotoxic damage, and morphological and physiological changes in the tree species Prosopis laevigata were evaluated in order to assess its potential for remediation of mine tailings. P. laevigata plants were established in two treatments (reference substrate and tailing substrate) under greenhouse conditions. Every 2 months, six individuals were selected per treatment for 1 year. From each individual, macromorphological (height, stem diameter, and number of leaves), micromorphological (stomatal coverage and stomatal index), and physiological parameters (chlorophyll content) were evaluated, as well as the concentration of Pb, Cu, Cd, Cr, Fe, and Zn in root and foliar tissue. Genetic damage was assessed by the comet assay in foliar tissue. These parameters were evaluated in adult individuals established in mine tailings. Roots bioaccumulated significantly more HM compared to foliar tissue. However, the bioaccumulation pattern in both tissues was Fe > Pb > Zn > Cu. The plants in tailing substrate reduced significantly the morphological and physiological characters throughout the experiment. Only the bioaccumulation of Pb affected significantly the levels of genetic damage and the number of leaves, while Zn reduced plant height. The percentage of plants that have translocation factor values greater than 1 are Cu (92.9) > Fe (85.7) > Pb (75.0) > Zn (64.3). P. laevigata has potential to phytoremediate environments contaminated with metals, due to its dominance and establishment in abandoned mine tailings, and its ability to bioaccumulate HM unaffecting plant development, as well as their high levels of HM translocation.