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Microplastic pollution has been widely studied in the marine environment, but is much less explored in terrestrial waters, notably in China. Therefore, we studied the degree of microplastic pollution in surface waters of Lake Ulansuhai, a major freshwater lake in the Yellow River basin of northern China. Results show microplastic concentrations ranging from 1760 ± 710 to 10,120 ± 4090 n/m3. The microplastic spatial distribution is heterogeneous, with higher levels near the drainage canal entrance of Lake Ulansuhai, and a downward trend from north to south in the lake. The main type of microplastics is colored particles, including fibers as the most abundant. More than 80% of microplastics were smaller than 2 mm. FTIR analysis results show that the main plastics were polyethylene, polystyrene and polybutylene terephthalate. There were also some metallic elements adsorbed on the surface of microplastics, such as Fe, Ca and Zn, detected by energy-dispersive spectrometry. The presence of metallic elements may worsen water pollution.

To identify applicability of an infiltration basin-type artificial recharge system on an alluvial aquifer in a high-density greenhouse complex area, South Korea, a field-scale study was performed. In this area, enormous amounts of groundwater were extracted to form water-curtain on the space between interior- and exterior-plastic film of the double-layer plastic greenhouse during winter seasons. The water-curtain kept the indoor air temperature of greenhouse warm during winter night, therefore, this area has repeatedly experienced a shortage of groundwater winter seasons due to excessive pumping. This study experimentally tried to alleviate this groundwater shortage problem in winter by applying the infiltration basin-type artificial recharge method. Drainage water flowing drainage canal was used as artificially recharged water, which was transported into the small-scale test-cell (length × width × depth = 7 × 7 × 3 m 3 ) and introduced into relatively high-permeable alluvial aquifer with gravitational pressure. Two kinds of artificial recharge experiments with recharge rates of 80,000 and 100,000 L day −1 were conducted in the test-cell during eight and fifteen experimental days, respectively. Results of the experiments exhibited a significant increase of groundwater levels in the shallow aquifer. Average groundwater level increment was in proportion to the recharge rate. Daily periodic change of groundwater levels exhibited that the recharged water was used for forming water-curtain on greenhouses during night times. Meanwhile, cold temperature of the recharged water significantly dropped the alluvial groundwater temperature, which was not suitable to irrigate crops directly. Innovative methods for solving this cooled groundwater problem are required.

The Indonesian government committed to restoring over 2 million ha of degraded peatland by the end of 2020, mainly to reduce peat fires and greenhouse gas emissions. Although it is unlikely the government will meet this target, restoration projects are still underway. One restoration strategy involves blocking peatland drainage canals, but the consequences of this for smallholder farmers whose livelihoods are dependent on agriculture are unclear. This paper investigates perceived impacts of canal blocks on smallholder farmers and identifies factors that affect their willingness to accept canal blocks on their land. We use data from 181 household questionnaires collected in 2018 across three villages in Jambi province, Sumatra. We found that the majority of respondents would accept canal blocks on their farms, perceiving that the blocks would have no impact on yields or farm access, and would decrease fire risk. Respondents who would not accept blocks on their farms were more likely to use canals to access their farms and perceive that canal blocks would decrease yields. The majority of farmers unwilling to accept canal blocks did not change their mind when provided with an option of a block that would allow boat travel. Our results improve understanding of why some smallholders may be unwilling to engage with peatland restoration. Further research is needed to understand the impact of canal blocks on smallholders’ yields. Engaging with stakeholders from the outset to understand farmers’ concerns, and perceptions is key if the government is to succeed in meeting its peatland restoration target and to ensure that the costs and benefits of restoration are evenly shared between local stakeholders and other actors.

Macrophytes are one of the biological elements for assessing the ecological status. Macrophyte communities were studied in six artificial (drainage canal and ditches) or modified watercourses (regulated rivers). In order to assess the ecological status of the watercourses, studies were carried out with the use of the Macrophyte Index for Rivers (MIR) proposed in the Water Framework Directive. Macrophyte communities were mainly represented by helophytes (12 species in total), and the highest percentage area cover (50–75% of the site) was observed for pleustophytes ( Lemna spp. ). Macrophytes communities were affected by the gradients of hydromorphological (canal modification, flow type, and shading) and parameters water quality (nutrients and water transparency). The relationships were highly species-specific. In accordance with the MIR values, the ecosystems were classified as having poor (drainage canal), moderate (regulated rivers), or good (drainage ditches) ecological status.

The examination of wastewater and effluents flowing into receiving water bodies is crucial for identifying pollutant sources and implementing scenarios to reduce them. In this study, QUAL2kw was used to identify, assess, and predict the pollutant load of a drainage canal located 6 km away from Anzali Wetland. Initially, the model was calibrated and validated with data collected in 2017. The NRMSE of the values was mostly less than 20%, except for flow accounting for 37% during calibration. The model did well in simulating EC and ammonium levels, but there is room for improvement in predicting nitrate and inorganic P concentrations. Field visits and sampling were done during the rice growth period in April–June 2021. The model was simulated for a three-time series in 2021; the simulation showed that May was the most critical, as the levels of nitrates, ammonium, and phosphates were at their highest. This study focused on the employment of QUAL2kw to drainage canals, emphasizing its suitability for regions with limited data availability. Scenarios were employed to explore ways to enhance water resource quality, showcasing how targeted interventions can effectively mitigate nutrient loads. Scenarios were considered to reduce nutrient loads. Reducing the amount of fertilizer led to a 9–27% while applying water stress resulted in a 0.1–1% reduction in the discharge outflow from the drain and less than 1% reduction in the amount of ammonium and nitrate. It is concluded that reduction in fertilization is more efficient in reducing concentrations and pollutant loads at the exit point of the canal to water resources compared to applying water stress since urea fertilizer contains a high percentage of nitrogen, and declining water application can enhance the soil’s nutrient retention ability but only to a small degree.

Tropical peatlands in Southeast Asia have experienced widespread subsidence due to forest clearance and drainage for agriculture, oil palm and pulp wood production, causing concerns about their function as a long-term carbon store. Peatland drainage leads to subsidence (lowering of peatland surface), an indicator of degraded peatlands, while stability/uplift indicates peatland accumulation and ecosystem health. We used the Advanced Pixel System using the Intermittent SBAS (ASPIS-DInSAR) technique with biophysical and geographical data to investigate the impact of peatland drainage and agriculture on spatial patterns of subsidence in Selangor, Malaysia. Results showed pronounced subsidence in areas subjected to drainage for agricultural and oil palm plantations, while stable areas were associated with intact forests. The most powerful predictors of subsidence rates were the distance from the drainage canal or peat boundary; however, other drivers such as soil properties and water table levels were also important. The maximum subsidence rate detected was lower than that documented by ground-based methods. Therefore, whilst the APSIS-DInSAR technique may underestimate absolute subsidence rates, it gives valuable information on the direction of motion and spatial variability of subsidence. The study confirms widespread and severe peatland degradation in Selangor, highlighting the value of DInSAR for identifying priority zones for restoration and emphasising the need for conservation and restoration efforts to preserve Selangor peatlands and prevent further environmental impacts.

The present study was designed to investigate the cytotoxic effects and bioaccumulation of heavy metals iron (Fe), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb), manganese (Mn), nickel (Ni), and chromium (Cr) in different parts (muscle, gills, and liver) of Tilapia zillii occurring in polluted drainage canal and fish farm, which is located in Abiece region in front of village number 10, Alexandria governorate, Egypt. Results of water analysis revealed the concentration of Cd, Pb, Mn, Ni, and Cr exceeded the limits defined by the American Public Health Association (APHA) in the polluted drainage canal. In addition, the concentration of Ni elevated to the standard limits of APHA and Cu was not detected in the fish farm. Different types of chromosomal aberrations were recorded (e.g., stickiness, fragmented chromosomes, centromeric gaps, chromatid break, chromatid deletion, and tetraploid). Micronucleus frequency was found to be 5.58 in the polluted drainage canal group and 0.32 in the fish farm group. Other nuclear abnormalities such as blebbed nucleus, segmented nucleus, enucleated erythrocyte, kidney-shaped nucleus, heart-shaped nucleus, polymorphic irregular nuclei, binucleated cell, nuclear fragmented erythrocyte, long nucleus, putative fragmented notched nucleus, lobed nuclei, fused erythrocytes, necrotic erythrocyte, and vacuolated nucleus were recorded. The total of erythrocytes nuclear morphological abnormalities was 70.33% in the polluted drainage canal and 1.78% in the fish farm.

As an emerging organic pollutant, microplastics in the ocean have been the subject of much study. However, there is a lack of research on freshwater environments, notably in sediment, China. Microplastics contamination in sediment of Lake Ulansuhai has been investigated in the study, and its concentration range was from 24 ± 7 to 14 ± 3 n/kg. Further, it exhibited a difference in spatial distribution with high content in the north zone of the lake far from the entrance of the drainage canal and it has a decreasing tendency with the flow from north to south in lake. Colored plastic particles acted as the dominated pollution type, and more than 79.69% of microplastics were smaller than 2 mm in size, existed as the form of fibers. FTIR results mirrored that the main types of microplastics were polyethylene, polyethylene terephthalate, polypropylene, and polyvinyl chloride. Results obtained from SEM/EDS showed that there were cracks, holes, and irregular curls on the surface of it, and these microplastics may provide attachment sites for other pollutants. The appearance of metallic elements such as Al, Ni, and Fe showed that microplastics and other pollutants in Lake Ulansuhai have a combined effect, which may aggravate the degree of pollution in the lake.

Aim Exotic species are a major threat to biodiversity and have modified native communities worldwide. Invasion processes have been extensively studied, but studies on species richness and beta diversity patterns of exotic and native species are rare. We investigate such patterns among exotic and native fish communities in upland and lowland rivers to explore their relationship with environmental drivers. Location Northern Italy. Methods Exotic and native fish beta diversity patterns were investigated separately in lowland and upland sites using Local Contribution to Beta Diversity (LCBD) and Species Contribution to Beta Diversity (SCBD) analyses. To examine the main environmental variables affecting the LCBD, a Boosted Regression Trees (BRT) method was used. Community dispersion among and within stream orders was investigated with the PERMDISP test. Results In lowland sites, exotic species richness was higher than native species richness, especially in large rivers and drainage canals. An opposite trend was found in upland sites, where native species richness was higher than exotic species richness, especially in large rivers. No clear LCBD patterns were found along stream orders in the lowland, whereas higher stream orders in the upland showed the highest LCBD. Its patterns in upland and lowland sites were related to a number of factors, such as total suspended solids and total phosphorus. Community dispersion among stream orders did not show a relationship with environmental heterogeneity. SCBD values were positively correlated with species occupancy in the study area, and native species showed higher SCBD values than exotic species only in the uplands. Main conclusions Large rivers in the uplands are important in maintaining native fish diversity and should be protected against invasive fish. In contrast, most lowland rivers have suffered from biological homogenization. Some rare native species can show low contribution to beta diversity, but still need conservation actions due to their risk of local extinction.

1. Human activities have been a significant driver of environmental changes with tremendous consequences for carbon (C) dynamics. Peatlands are critical ecosystems because they store ~30% of the global soil organic pool and are particularly vulnerable to anthropogenic changes. The Zoige peatland on the eastern Tibet Plateau, as the largest alpine peatland in the world, accounts for 1% of global peat soil organic C storage. However, this peatland has experienced dramatic climate change including increased temperature and reduced precipitation in the past decades, which likely is responsible for a decline of the water-table and facilitated earthworm invasion, two major factors reducing soil organic carbon (SOC) storage of peatlands. 2. Because earthworms often are more active in low- than in high-moisture peatlands, we hypothesized that the simultaneous occurrence of water-table decline and earthworm invasion would synergistically accelerate the release of SOC from peatland soil. We conducted a field experiment with a paired split-plot design, i.e. presence vs. absence of the invasive earthworms (Pheretima aspergillum) nested in drained vs. undrained plots, respectively, for 3 years within the homogenous Zoige peatland. 3. Water-table decline significantly decreased soil water content and bulk density, resulting in a marked reduction of SOC storage. Moreover, consistent with our hypothesis, earthworm presence dramatically reduced SOC in the drained but not in the undrained peatland through the formation of deep burrows and decreasing bulk density of the lower soil layer over 3 years. The variation in SOC likely was due to changes in above-ground plant biomass, root growth and earthworm behaviour induced by the experimental treatments. 4. Synthesis and applications. We suggest that incentive measures should be taken to prevent further water-table decline and earthworm invasion for maintaining the soil carbon pool in Zoige peatland. Artificial filling of drainage canals should be implemented to increase the water-table level, facilitating the recovery of drained peatlands. Moreover, the dispersal of earthworms and their cocoons attached to the roots of crop plants and tree saplings from low-lying areas to the Zoige region should be prevented.