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Diazinon is an organophosphorus pesticide widely used in agriculture and household pest control, and its use also poses several environmental and health hazards. In this study, we investigated the spatial and temporal distribution of diazinon in Baiyangdian, evaluated its potential ecological risk and toxicity to aquatic organisms based on RQ (Risk quotient) and TU (Toxic unit) analysis, and assessed the potential effects of diazinon accumulation on probiotics and pathogens based on statistical analysis of high-throughput sequencing data. The results showed that diazinon in Baiyangdian posed a low to moderate chronic risk to sediment-dwelling organisms and a low toxicity effect on aquatic invertebrates, which was mainly concentrated in October and human-intensive areas. Meanwhile, increases in sediment electrical conductivity (EC), amorphous iron oxides content and phenol oxidase activity favored diazinon accumulation in sediments, whereas the opposite was the case for sediment organic carbon, β-1,4-glucosidase, phosphatase, catalase and pH, suggesting that environmental indicators play a key role in the behavior and distribution of diazinon. In addition, diazinon in heavily contaminated areas seem to inhibit the rare probiotics (Bifidobacterium adolescentis and Serratia sp.), while promoted dominant pathogens (e.g., Burkholderia cenocepacia), which can lead to increased disease risk to humans and ecosystems, disruption of ecological balance and potential health problems. However, probiotic Streptomyces xiamenensis resist to diazinon would be a potential degrader for diazinon remove. In conclusion, this study unveiled the effects of diazinon pollution on wetland ecosystems, emphasizing ecological impacts and potential health concerns. In addition, the discovery of diazinon resistant probiotics provided new insights into wetland ecological restoration., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Toxic metals (TMs) in reservoir sediments pose significant risks to ecosystem security and human safety, yet their presence in the cascade reservoirs of the Lancang River remains understudied. This research examined TMs in core sediments from the Manwan (MW) and Dachaoshan (DCS) cascade reservoirs, aiming to elucidate contamination characteristics, controlling factors, and source-specific ecological risks. The study revealed that the concentrations of As, Cd, Cr, Cu, Hg, Ni, and Zn in the MW Reservoir (37.3, 0.54, 95.1, 44.0, 0.09, 44.8, and 135.7 mg/kg) were notably higher compared to the DCS Reservoir (14.6, 0.30, 82.6, 31.0, 0.08, 36.6, and 108.7 mg/kg). While both reservoirs demonstrated elevated contamination levels of Cd and Hg, the MW Reservoir also exhibited high levels of As, whereas the DCS Reservoir showed relatively high levels of Pb. Mining activities in upstream metal deposits significantly correlated Cd, Hg, and Zn in the MW Reservoir with sulfur. In both reservoir sediments, Cr and Ni displayed a greater affinity for iron oxides, while As, Cd, Cu, Hg, and Zn showed more affinity with manganese oxides. Ecological risk index (RI) values in half of the sediments from the MW Reservoir ranged from 300 to 600, denoting a significant ecological risk. Conversely, in the DCS Reservoir, 93.3 % of the sediments exhibited RI values between 150 and 300, signifying a moderate ecological risk. Source-oriented ecological risks highlighted the need for particular attention to Cd from anthropogenic sources in the MW Reservoir. These findings underscore the importance of implementing measures for TM contamination prevention and control, contributing to strategic planning for sustainable water resource management in the Lancang-Mekong River., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Abstract Understanding the integrated effect of external factors (e.g., human activities) and internal factors (e.g., hydrodynamics, sediment properties) on metal(loid) distributions is necessary for relevant decision-makers to develop river basin management strategies. In attempts to understand the possible causes of the distribution of nine target metal(loid)s in riverbed sediments across Xijiang River basin in China, we grouped and portrayed the multiple metal(loid) distributions by calculating metal(loid)'s normalised-and-weighted average concentrations, and then canonical correlation analysis combined with a series of statistical operations, collectively called optimized CCA analysis, was applied to quantify the strength of relationship between multiple metal(loid) distribution and integrated effect of internal-external factors. Results showed that the target metal(loid)s can be divided into three groups according to their distribution patterns: Group A (including Zn, As, Cd, Sb and Pb), Group B (including Cr, Ni and Cu) and Group C (including Tl). Among them, metal(loid)s in Group A was significantly enriched in comparison with the reference values of Chinese sediments, and the wide-ranging accumulation of Cd and Sb in the whole study area needs paying great attention to. For those metals in natural states (e.g., metals in Group B), the affinity of sediment (e.g., Fe and Mn oxides) is responsible for their distributions. By contrast, when metal(loid)s (e.g., metal(loid)s in Group A and Group C) had obvious anthropogenic sources, the interferences of anthropogenic inputs (e.g., non-ferrous metal enterprises' waste-discharging activities) and the specific sedimentary characteristics (e.g. karst topography and low-energy hydrodynamic depositional conditions) in study area can weaken the correlation between the binding affinity of sediment and the contents of metal(loid)s. The optimized CCA analysis can be an alternative and advantageous statistical operation for determining the main types of causes of multiple metal(loid) distribution in the case of observations with relatively low case-per-variable ratios. Graphical abstract Unlabelled Image Highlights • Metal(loid) distributions in sediments are controlled by external-internal factors. • A procedure was developed based on optimized canonical correlation analysis. • This procedure was applied to study sediment metal(loid)s in Xijiang River basin. • Relationship between metal distributions and related factors could be quantified. • The contributions of related factors can reflect the extent of human interference. [ABSTRACT FROM AUTHOR]

Metal enrichment in lake sediments originating from multiple sources can threaten both the aquatic ecosystem and human health. Therefore, assessment of the eco-environmental risks and potential sources of metals in the sediments is essential for effective lake management. Here, we analyzed the sediment metal contents of Kaptai Lake, the largest lake in Bangladesh for the first time with this study. The results indicated that only Cr and Ni contents among the metals studied exceeded the probable effect concentrations (PEC) at 25.42 % and 55.93 % of the sampling stations, respectively. All metals at most sampling stations showed low contamination and low ecological risk based on the individual indices (geoaccumulation index, contamination factor, ecological risk factor, enrichment factor and modified hazard quotient). There was no significant risk from the combined metals in the sediments of the lake according to the synergistic indices (toxic risk index, Nemerow risk index, ecological risk index, Nemerow pollution index and pollution load index). Organic matter and silt were significant sediment parameters that favored the accumulation of Cr, Fe, Cu, Pb and Mn. In the absolute principle component scores-multiple linear regression model (APCS-MLR), five potential sources of metals were identified in the sediments: Zn, Mn, Co and Cd mainly from natural sources and to a lesser extent from agricultural and aquacultural activities, Ni, Cr and Fe from parent materials, Pb and Cu mainly from natural sources and to a lesser extent from vehicle emissions, Hg and U from lithogenic sources, and As from natural sources. This study will improve our knowledge of the sedimentary metal contents of Kaptai Lake and provide helpful information for developing effective lake management and pollution control strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

We investigated the long-term effects (6 years) of sediment improvement and submerged plant restoration of a subtropical shallow urban lake, Hangzhou West Lake China. To reveal the lake ecosystems variations, we analyzed the sediment properties, submerged macrophyte characteristics, sediment microorganisms, and benthic macroinvertebrate communities from 2015 to 2020. The ecological restoration project decreased sediment TP and OM, increased submerged macrophyte biomass and sediment microbial diversity, and improved the benthic macroinvertebrate communities in the restored area. The sediment TP decreased from 2.94 mg/g in 2015 to 1.33 mg/g in 2020. The sediment OM of the restored area decreased from 27.44 % in 2015 to 8.08 % in 2020. Principal component analysis (PCA) confirmed that the restoration improved the sediment conditions, making it suitable for the growth of submerged macrophytes, and then sped up the restoration and reconstruction of the lake ecosystem. These results have significant implications on the ecological management of shallow lakes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Abstract: Sonneratia caseolaris, a superior mangrove species characterized by rapid growth and proliferation, has been introduced to Futian Mangrove National Nature Reserve, Shenzhen, China for mangrove restoration since 1993. However, the effect of Sonneratia plantation on the macrobenthic infaunal community, a vital component of energy flow and nutrient recycling in mangrove ecosystems, remains obscure. The present study aimed to answer this question by determining the macrobenthic infaunal community, habitat characteristics and physico-chemical properties of sediment in the vegetated sites, dominated by different mangrove species (Kandelia obovata, Avicennia marina and S. caseolaris), and un-vegetated mudflat at four sampling times from August 2008 to September 2009. Results showed that the presence of Sonneratia can enhance the biodiversity of macrobenthic infauna in terms of Shannon–Weaver index (H′), compared to the mudflat, since August 2008 onwards. Multivariate analyses (CLUSTER and SIMPER) showed that the macrobenthic infaunal community in the Sonneratia site was different from all the other sites due to higher abundance of deposit and filter feeders, including Limnodriloides sp., Capitella capitata, Potamilla acuminata, Tharyx sp. and Ampharete arctica. The presence of Sonneratia, however, could not significantly alter the sediment properties. Spearman correlation analysis revealed that H′ was negatively correlated with cadmium concentration whereas distance-based linear model (DistLM) suggested that cadmium was a significant predictor variable correlating with the macrobenthic infaunal community. The higher cadmium concentration in August 2008 explained why H′ was lower and different macrobenthic infaunal communities were observed compared to the other sampling times. However, cadmium was the only significant predictor variable explaining 14.9% total variation, suggesting that the macrobenthic infaunal community was generally not affected by the sediment properties. Therefore, we concluded that Sonneratia plantation in the open mudflat can enhance the biodiversity of macrobenthic infauna in view of higher habitat complexity (e.g. presence of pneumatophores, below-ground vegetation and litter) on condition that the cadmium concentration was below the harmful level. [Copyright &y& Elsevier]

Abstract: Tidal creeks are an important structure of salt marshes in estuarine ecosystems, providing valuable ecosystem services to wildlife in the estuary. To determine the effects of environmental heterogeneities within tidal creeks on the features of crab burrows, we divided a typical creek section into four parts (i.e., microhabitats): bottom, slope, edge and flat, investigated the distribution of crab burrows and sediment properties on creek sections in the Yangtze River estuary, and compared the burrow distribution in tidal creeks with that in non-creek areas. Our results showed that from the creek bottom to flat soil water content declined (F 3,60 =93.8, p <0.001), and the variations of other sediment physical and chemical properties associated with the change of soil water content were significant among the microhabitats on the creek sections (p <0.001 for pH, conductivity, and grain size). No crab burrows were found at the creek bottom. The burrows on the slope were smaller in size (p <0.001 for burrow opening diameter) while the density was higher than that at the edge and on the flat (F 2,45 =31.2, p <0.001). Moreover, although the correlations between burrow distribution and sediment properties varied among the microhabitats on the creek sections, crabs generally selected relatively solid sediments to build their burrows. On the slope, there was a significantly negative relationship between burrow density and soil water content (r 2 =0.53, p <0.001). At the edge, the correlation between total burrow opening area and soil water content was significantly negative (r 2 =0.44, p <0.002). The density of small crab burrows (<10mm) was greater, but that of large burrows (>10mm) was lower in tidal creeks than in non-creek habitats. Therefore, sediment properties showed a gradual transition from hydrophytic to terrestrial environments on the creek section, which caused significant differences of burrow distribution among the microhabitats. The creeks of tidal salt marshes could affect ecological processes and functioning through affecting crab burrows. [Copyright &y& Elsevier]

A 14.6 m long profile from the northern part of the Hulun lake, the furthest north of the large lakes of China, has provided a sedimentary and diatom record since the late Glacial. The chronological sequence was established based on 10 radiocarbon dates. Sedimentological study and diatom analysis are synthesized for the reconstruction of the history of lake-level changes. The results show that the Hulun basin was not occupied by a lake during the Last Glaciation. A rapid transition to a deep lake occurred since 12 850 yr B.P., and this high level phase lasted to 11 200 yr B.P., although there existed several subordinate lake level fluctuations. An abrupt lake level drop and dry climatic conditions occurred during 11 200–10 600 yr B.P. The lake became deeper again from 10 600 yr B.P. to 10 300 yr B.P. Hulun lake at the early Holocene was characterized by the low lake-level, and the lake level rose again in 7200–5800 yr B.P., though the lake-levels changed quite variably. A dry condition occurred and lake level declined again during 5800–3000 yr B.P. The presence of the palaeosol on the top of this profile indicates the persistence of low lake levels after 3000 yr B.P. The comparison with the other lake-level records from northern China has suggested that the Hulun Lake shows a different lake level history from the lakes in monsoon areas. [ABSTRACT FROM AUTHOR]

The evaluation of trace elements (TEs) in sediments of dam lakes is crucial for maintaining ecosystem health. Therefore, it is very important to determine their concentrations, pollution status, sources, controlling factors and ecological risks in these ecosystems. Here, for the first time, we analyzed 14 TEs (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg and Pb) and sediment properties (organic matter (OM) and pH) in sediments from four dam lakes (Erfelek, Derbent, Suat Uğurlu and Saraydüzü) in the Black Sea Region of Turkey, which are used for different purposes and located on the different rivers or streams with different pollution levels. The results indicated that Al, V, Mn, Fe, Cu, Zn, As, Pb and Sb concentrations were lower in the Erfelek Dam Lake which has been used for drinking water supply, indicating that it is more protected than other dam lakes. However, Al, V, Mn, Fe, Co, Cu and Sb concentrations were higher in the Suat Uğurlu Dam Lake on the Yeşilırmak River which is moderately polluted. According to sediment contamination indices, there was low contamination in the sediments of all dam lakes. Similarly, the assessment of ecological risk posed by TEs indicated low eclogical risk in the dam lakes. Sediment OM and pH were found to be important control factors affecting the distribution of TEs in the dam lakes sediments. Correlation and factor analyses suggested that all TEs in the sediments of dam lakes mainly originated from geogenic sources., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Giant sand waves (heights >10 m) are widely developed on the Taiwan Banks, the distribution pattern, morphotypes and morphometric relationships of which have not yet been fully clarified. Based on multi-beam bathymetric swath data covering 780 line km of survey track, giant sand waves with heights up to 22.5 m and wavelengths up to 2115 m have been recorded. The relationship between height (H) and wavelength (L) of the complete data set follows the regression trend of H mean = 0.0625 L 0.8152 (r = 0.94), which is in good general agreement with a previously determined average global trend of H mean = 0.0677 L 0.8098. This global trend did not include any data from the China seas. The giant sand waves have been grouped into four morphotypes, namely double-crested, symmetric, symmetric-asymmetric and asymmetric forms. The individual bedform morphotypes and their spatial distribution were investigated in relation to water depth, textural characteristics of the sediment, and the hydrodynamic conditions recorded by several 25-hour repeated ship-based current observations. The relationship between mean water depth (D) and mean sand wave height (H) and mean wavelength (L) on the Taiwan Banks are H mean = 0.29 D (r = 0.35) and L mean = 36 D (r = 0.42), respectively. With increasing water depth, the shape of the sand wave becomes gentler. It is found that the coarser sediment (median grain size of 0.51–0.54 mm) and stronger flow in the present study may contribute to the larger H / D and L / D ratios at the given water depths than other sand wave fields. And flows of varying from equal to unequal northerly and southerly components correspond with sand waves from symmetrical to asymmetrical forms. A decrease in velocity and a veering in direction of flows have been observed over the giant sand waves, indicating the interaction between large bedforms and the near-bed water layer in the study area. • Four types of giant sand waves are distributed separately on the Taiwan Banks. • A mean H–L relation for giant sand waves is derived: H = 0.0625 L0.8125 (r = 0.94). • Stronger flow and coarser sediment contribute to the larger H/D and L/D ratios. • Influence of local environmental factors on sand wave variability are discussed. [ABSTRACT FROM AUTHOR]

The emerging pollutants antibiotic resistance genes (ARGs) are prevalent in aquatic environments such as estuary. Coastal mangrove ecosystems always serve as natural wetlands for receiving sewage which always carry ARGs. Currently, the research considering ARG distribution in mangrove ecosystems gains more interest. In this work, we investigated the diversity of ARGs in an urban estuary containing mangrove and nonmangrove areas of the South China Sea. A total of 163 ARGs that classified into 22 resistance types and six resistance mechanisms were found. ARG abundance of the samples in the estuary is between 0.144 and 0.203. This is within the general range of Chinese estuaries. The difference analysis showed that abundances of total ARGs, six most abundant ARGs (mtrA, rpoB, rpoC, rpsL, ef-Tu, and parY), the most abundant resistance types (elfamycin, multidrug, and peptide), and the most abundant resistance mechanism (target alteration) were significantly lower in mangrove sediment than that in nonmangrove sediment (p < 0.05). Network and partial redundancy analysis showed that sediment properties and mobile genetic elements were the most influential factors impacting ARG distribution rather than microbial community. The two factors collectively explain 51.22% of the differences of ARG distribution. Our study indicated that mangrove sediments have the capacity to remove ARGs. This work provides a research paradigm for analysis of ARG prevalence and proliferation in the subtropical marine coastal mangrove ecosystem., (© 2019 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

Concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn), grain sizes, and concentrations of organic carbon (Corg) were measured in 323 river sediment samples from the Pearl River Delta (PRD). Results showed that the heavy metal concentrations in the sediments ranged from 1.6-93 mg/kg for As, 0.04-9.3 mg/kg for Cd, 2-315 mg/kg for Cr, 1.1-352 mg/kg for Cu, 0.01-0.67 mg/kg for Hg, 11-221 mg/kg for Pb, and 11-1234 mg/kg for Zn. The highest values of As, Cr, Cu, Hg, Pb, and Zn appeared in the Beijiang River, whereas Cd was high in the Xijiang River. The overall sediment quality in the area with respect to metal concentrations generally met the primary standard criteria of China (Marine Sediment Quality), except for Cd and Cu. The spatial distributions of the heavy metals were influenced by both grain sizes and Corg concentrations. The Igeo geo-accumulation index indicated that there was no significant Cr, Cu, Hg, or Zn pollution, slight to moderate pollution by As and Pb, and moderate Cd pollution in the study area. Spatial distributions of an eco-toxicological index based on probable effect levels indicated that there was a 21% probability that the combination of the seven metals was exerting a toxic stress in the PRD river sediments., (Copyright © 2018 Elsevier Ltd. All rights reserved.)