HIV Services Uptake Among People Living with HIV in Jiangsu Province, China: A Cross-Sectional Study.

Healthcare disparities are common among people living with HIV (PLWH) in China and likely impact access to HIV services. This study aimed to assess the current status of access to HIV services among PLWH and explore the correlates of service uptake using baseline data from a prospective cohort study among PLWH in Jiangsu Province. Guided by Andersen's behavioral model, univariable and multivariable logistic regressions were conducted to identify factors associated with access to HIV services. Out of 8989 eligible PLWH included in this study, 46.4% perceived difficulty in seeing a healthcare professional for HIV treatment services in 2021-2022. PLWH aged 18-34 years (adjusted odds ratio [AOR] = 1.69, 95% CI 1.32-2.15), 35-39 years (AOR = 1.33, 95% CI 1.08-1.65), identified as a bisexual/other (AOR = 1.14, 95% CI 1.01-1.29), had a college and above education (AOR = 1.32, 95% CI 1.07-1.63), and perceived moderate (AOR = 1.70, 95% CI 1.51-1.91) and severe (AOR = 2.20, 95% CI 1.94-2.49) levels of HIV stigma were more likely to perceive difficulty in seeing healthcare professionals for HIV treatment in 2021-2022. Living in northern Jiangsu was also associated with increased odds of perceiving difficulty in seeing healthcare professionals for HIV treatment (AOR = 1.12, 95% CI 1.00-1.26). These findings underscore the need for innovative solutions to eliminate the practical barriers to HIV services utilization among PLWH who are bisexual, well-educated, and effective HIV-related stigma reduction interventions.

Social Network Strategies to Distribute HIV Self-testing Kits: A Global Systematic Review and Network Meta-analysis.

Introduction: Social network strategies, in which social networks are utilized to influence individuals or communities, are increasingly being used to deliver human immunodeficiency virus (HIV) interventions to key populations. We summarized and critically assessed existing research on the effectiveness of social network strategies in promoting HIV self-testing (HIVST). Methods: Using search terms related to social network interventions and HIVST, we searched five databases for trials published between January 1st, 2010, and June 30th, 2023. Outcomes included uptake of HIV testing, HIV seroconversion, and linkage to antiretroviral therapy (ART) or HIV Care. We used network meta-analysis to assess the uptake of HIV testing through social network strategies compared with control methods. A pairwise meta-analysis of studies with a comparison arm that reported outcomes was performed to assess relative risks (RR) and their corresponding 95% confidence intervals (CI). Results and discussion: Among the 3,745 manuscripts identified, 33 studies fulfilled the inclusion criteria, including one quasi-experimental study, 17 RCTs and 15 observational studies. Networks HIVST testing was organized by peers (distributed to known peers, 15 studies), partners (distributed to their sexual partners, 10 studies), and peer educators (distributed to unknown peers, 8 studies). The results showed that all of the three social network distribution strategies enhanced the uptake of HIV testing compared to standard facility-based testing. Among social networks, peer distribution had the highest uptake of HIV testing (79% probability, SUCRA 0.92), followed by partner distribution (72% probability, SUCRA 0.71), and peer educator distribution (66% probability, SUCRA 0.29). Pairwise meta-analysis showed that peer distribution (RR 2.29, 95% CI 1.54-3.39, 5 studies) and partner distribution (RR 1.45, 95% CI 1.05-2.02, 7 studies) also increased the probability of detecting HIV reactivity during testing within the key population when compared to the control. Linkage to ART or HIV Care remained comparable to facility-based testing across the three HIVST distribution strategies. Conclusions: Network-based HIVST distribution is considered effective in augmenting HIV testing rates and reaching marginalized populations compared to facility-based testing. These strategies can be integrated with the existing HIV care services, to fill the testing gap among key populations globally.PROSPERO Number: CRD42022361782.

Disparities in healthcare access and utilization among people living with HIV in China: A scoping review and meta-analysis.

BACKGROUND: This review aims to assess the status of healthcare disparities among people living with HIV (PLWH) in China and summarize the factors that drive them. METHODS: We searched PubMed, Web of Science, Cochrane Library, Scopus, China National Knowledge Infrastructure (CNKI) and China Wanfang for studies published in English or Chinese. Studies focusing on any disparities in healthcare services among PLWH in China and published between January 2000 and July 2022 were included. RESULTS: In all, 51 articles met the inclusion criteria, with 37 studies reporting HIV-focused care, and 14 reporting non-HIV-focused care. PLWH aged ≥45 years (vs. <45 years), female (vs. male), ethnic minority (vs. Han), and cases attributed to sexual transmission (vs. injecting drug use) were more likely to receive ART. Females living with HIV have higher ART adherence than males. Notably, 20% [95% confidence interval (CI): 9-43%, I2 = 96%] of PLWH reported any illness in the previous 2 weeks without medical consultation, and 30% (95% CI: 12-74%, I2 = 90%) refused hospitalization when needed in the previous year. Barriers to HIV-focused care included inadequate HIV/ART knowledge and treatment side effects at the individual level; and social discrimination and physician-patient relationships at the community/social level. Structural barriers included medical costs and transportation issues. The most frequently reported barriers to non-HIV-focused care were financial constraints and the perceived need for medical services at individual-level factors; and discrimination from physicians, and medical distrust at the community/social level. CONCLUSION: This review suggests disparities in access and utilization of healthcare among PLWH. Financial issues and social discrimination were prominent reasons. Creating a supportive social environment and expanding insurance policies could be considered to promote healthcare equity.

Disparities in healthcare access and utilization among people living with HIV in China: a scoping review and meta-analysis.

Background Healthcare disparities hinder the goal of ending the HIV pandemic by 2030. This review aimed to understand the status of healthcare disparities among people living with HIV (PLWH) in China and summarize driving factors. Methods We searched six databases: PubMed, Web of Science, Cochrane Library, Scopus, China National Knowledge Infrastructure (CNKI), and China Wanfang. English or Chinese articles published between January 2000 and July 2022 were included if they focused on any disparities in access to and utilization of healthcare among PLWH in China. Grey literature, reviews, conferences, and commentaries were excluded. A random effects model was used to calculate the pooled estimates of data on healthcare access/utilization and identified the driving factors of healthcare disparities based on a socio-ecological framework. Results A total of 8728 articles were identified in the initial search. Fifty-one articles met the inclusion criteria. Of these studies, 37 studies reported HIV-focused care, and 14 focused on non-HIV-focused care. PLWH aged ≥ 45 years, female, ethnic minority, and infected with HIV through sexual transmission had a higher rate of receiving antiretroviral therapy (ART). Females living with HIV have higher adherence to ART than males. Notably, 20% (95% CI, 9-43%, I 2 = 96%) of PLWH with illness in two weeks did not seek treatment, and 30% (95% CI, 12-74%, I 2 = 90%) refused hospitalization when needed. Barriers to HIV-focused care included the lack of knowledge of HIV/ART and treatment side effects at the individual level, and social discrimination and physician-patient relationships at the community/social level. Structural barriers included out-of-pocket medical costs, and distance and transportation issues. The most frequently reported barriers to non-HIV-focused care were financial constraints and the perceived need for medical services at individual-level factors; and discrimination from healthcare providers, distrust of healthcare services at the community/social level. Conclusion This review suggests disparities in ART access, adherence, and utilization of non-HIV-focused care among PLWH. Financial issues and social discrimination were prominent reasons for healthcare disparities in PLWH care. Creating a supportive social environment and expanding insurance policies, like covering more medical services and increasing reimbursement rates could be considered to promote healthcare equity.

Controlling internal nitrogen and phosphorus loading using Ca-poor soil capping in shallow eutrophic lakes: Long-term effects and mechanisms.

Clean soil is a potential capping material for controlling internal nutrient loading and helping the recovery of macrophytes in eutrophic lakes, but the long-term effects and underlying mechanisms of clean soil capping under in-situ conditions remain poorly understood. In this study, a three-year field capping enclosure experiment combining intact sediment core incubation, in-situ porewater sampling, isotherm adsorption experiments and analysis of sediment nitrogen (N) and phosphorus (P) fractions was conducted to assess the long-term performance of clean soil capping on internal loading in Lake Taihu. Our results indicate that clean soil has excellent P adsorption and retention capacity as an ecologically safe capping material and can effectively mitigate NH4+-N and SRP (soluble reactive P) fluxes at the sediment-water interface (SWI) and porewater SRP concentration for one year after capping. The mean NH4+-N and SRP fluxes of capping sediment were 34.86 mg m-2 h-1 and -1.58 mg m-2 h-1, compared 82.99 mg m-2 h-1 and 6.29 mg m-2 h-1 for control sediment. Clean soil controls internal NH4+-N release through cation (mainly Al3+) exchange mechanisms, while for SRP, clean soil can not only react with SRP due to its high Al and Fe content, but also stimulate the migration of active Ca2+ to the capping layer, thus precipitating as Ca-bound P (Ca-P). Clean soil capping also contributed to the restoration of macrophytes during the growing season. However, the effect of controlling internal nutrient loading only lasted for one year under in-situ conditions, after which the sediment properties returned to pre-capping conditions. Our results highlight that clean Ca-poor soil is a promising capping material and further research is needed to extend the longevity of this geoengineering technology.

Cross-sectional study of factors affecting the receipt of mental health education in older migrants in China.

BACKGROUND: Population migration in China has increasingly included middle-aged and older populations. Relatedly, the lack of mental health education among China's older migrants is still an important but neglected problem. This study aimed to understand the current situation of mental health education received by the older migrant population in China and to explore related influencing factors. METHODS: This cross-sectional study included 5729 older migrants who participated in the 2017 China Migrants Dynamic Survey. The independent variables included four components: demographic and socioeconomic characteristics, migration factors, public health service utilization, and social integration factors. Data were analyzed using the chi-square test for single factors and a binary logistic regression model for multiple factors. RESULTS: A total of 1749 older migrants received mental health education, for a receipt rate of 30.53%. Regression analysis showed that older migrant individuals who had an average monthly household income > 3000 CNY, self-rated their health as healthy, had chronic diseases, had heard of National Basic Public Health Services, had established health records, received ≥2 types of health education were willing to integrate into the local population, and were highly involved in the community were more likely to receive mental health education. Older migrants who were ≥ 70 years old, had an elementary school education or below, had difficulties in the local community, had migrated ≥11 years prior, moved for their offspring, and moved across provinces were less likely to receive mental health education. CONCLUSIONS: The older migrant population does not receive sufficient mental health education. Mental health interventions should be tailored to the characteristics of older migrants to increase their mental health literacy and meet their psychological needs.

The status of emotional labour and its influence on job burnout among village doctors during the COVID-19 pandemic in China: a cross-sectional study.

BACKGROUND: Village doctors in China are not only the gatekeepers of rural residents' health but also the net bottom of the medical security system. However, emotional labour is increasingly threatening the stability of the rural primary medical system. In addition, the ongoing coronavirus disease 2019 (COVID-19) pandemic has further exposed the vulnerability of human resources in China's rural health system. This study aims to evaluate the current situation of emotional labour among village doctors and explore the impact of emotional labour on job burnout during the COVID-19 pandemic in China. METHODS: A cross-sectional survey was conducted in December 2021 in Shandong Province. We used structured questionnaires to collect data, including sociodemographic characteristics, emotional labour, and job burnout. Data were analysed by t test, analysis of variance (ANOVA), Pearson correlation analysis, and hierarchical multiple linear regression. RESULTS: A total of 1,093 village doctors from Shandong Province participated in the study. More than half of the participants were male (62.40%) and were between 41 and 50 years old (53.43%). The total mean score of emotional labour was 3.17 ± 0.67, of which the surface acting (SA) score was 2.28 ± 0.90, and the deep acting (DA) score was 3.91 ± 0.93. There were significant differences in SA according to gender and work content (P < 0.05) and in DA according to gender, age, education level, and work content (P < 0.05). Pearson correlation analysis showed that SA was positively correlated with job burnout (P < 0.001), and DA was negatively correlated with job burnout (P < 0.001). Hierarchical multiple linear regression analysis revealed that 29% of the variance in job burnout is attributable to SA (ß = 0.530, P < 0.001) and DA (ß = -0.154, P < 0.001). CONCLUSION: Village doctors in Shandong Province performed moderate levels of emotional labour during the COVID-19 pandemic. SA had a significant positive effect on job burnout, while DA had a significant negative effect on job burnout among village doctors. Administrators should enhance training on emotional labour for village doctors to play a positive role in alleviating their job burnout.

Association of individual resilience with organizational resilience, perceived social support, and job performance among healthcare professionals in township health centers of China during the COVID-19 pandemic.

Background: Primary healthcare professionals were overworked and psychologically overwhelmed during the COVID-19 pandemic. Resilience is an important shield for individuals to cope with psychological stress and improve performance in crises. This study aims to explore the association of individual resilience with organizational resilience, perceived social support and job performance among healthcare professionals in township health centers of China during the COVID-19 pandemic. Methods: Data from 1,266 questionnaires were collected through a cross-sectional survey conducted in December 2021 in Shandong Province, China. Descriptive analysis of individual resilience, organizational resilience, perceived social support, and job performance was conducted. Pearson correlation analysis was used to examine the correlations among these variables, and structural equation modeling was performed to verify the relationships between these variables. Results: The score of individual resilience was 101.67 ± 14.29, ranging from 24 to 120. Organizational resilience (ß = 0.409, p < 0.01) and perceived social support (ß = 0.410, p < 0.01) had significant direct effects on individual resilience. Individual resilience (ß = 0.709, p < 0.01) had a significant direct effect on job performance. Organizational resilience (ß = 0.290, p < 0.01) and perceived social support (ß = 0.291, p < 0.01) had significant indirect effects on job performance. Conclusion: During the COVID-19 pandemic, the individual resilience of healthcare professionals in township health centers was at a moderate level. Organizational resilience and perceived social support positively affected individual resilience, and individual resilience positively affected job performance. Furthermore, individual resilience mediated the effect of organizational resilience and perceived social support on job performance. It is recommended that multiple stakeholders work together to improve the individual resilience of primary healthcare professionals.

Effect of dredging and capping with clean soil on the mitigation of algae-induced black blooms in Lake Taihu, China: A simulation study.

Sediment is an important source of matter that causes blackening and odor formation in a water body. The restoration of polluted sediment can suppress algae-induced black blooms to a certain degree. In this study, we compared the control effects of sediment dredging and capping with clean soil on algae-induced black blooms in Lake Taihu using indoor simulation experiments. In addition, we explored the driving effect of temperature on algae-induced black blooms using the method of gradual warming (18, 23, and 28 °C) during the experiment. No blackening of the water body was observed in the simulation stages I (18 °C) and II (23 °C), and the blackening and odor formation occurred within 3 d when the temperature increased to 28 °C in stage III, implying that high temperature was an important driving factor for algae-induced black blooms. Dredging and capping inhibited the blackening and odor formation to some extent, and the colorimetric values in the water columns were lower in the treatment groups than in the control group. At the end of the experiment, the colorimetric values of dredging and capping treatments were 56.5% and 96.7% of the colorimetric value of the control group, respectively. The control effect of dredging on the blackening elements, i.e., Fe2+ and S2- and the main odor forming compounds, i.e., dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) was observed in stage II (11-20 d) and stage III (21-27 d), respectively, and the inhibition ability of dredging to suppress algal-induced black blooms was superior than that of capping with clean soil.

Understanding the Heavy Metal Pollution Pattern in Sediments of a Typical Small- and Medium-Sized Reservoir in China.

Heavy metal pollution in sediments is a common environmental issue in small- and medium-sized reservoirs not only in China but also worldwide; however, few interpretations of the pollution pattern exist. Based on the analyses of accumulation characteristics, ecological risks, and source apportionments of eight heavy metals (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn) in sediments, we derived a paradigm to describe the pollution pattern of heavy metals in sediments of a typical small- and medium-sized Tongjiqiao Reservoir. The results showed high levels of Cd, Hg, and As pollutants in the surface and upper sediment layers of the pre-dam area. Additionally, As, Cd, Hg, and Pb pollutants peaked in the middle layers of the inflow area, indicating a high ecological risk in these areas. The positive matrix factorization results implied that industrial, agricultural, and transportation activities were the main sources of heavy metals. The heavy metal pollution pattern exhibited three distinct stages: low contamination, rapid pollution, and pollution control. This pattern explains the heavy metal pollution process in the sediments and will provide scientific guidance for realizing the green and sustainable operation and development of the reservoir.

COVID-19 Information Dissemination Using the WeChat Communication Index: Retrospective Analysis Study.

BACKGROUND: The COVID-19 outbreak has tremendously impacted the world. The number of confirmed cases has continued to increase, causing damage to society and the economy worldwide. The public pays close attention to information on the pandemic and learns about the disease through various media outlets. The dissemination of comprehensive and accurate COVID-19 information that the public needs helps to educate people so they can take preventive measures. OBJECTIVE: This study aimed to examine the dissemination of COVID-19 information by analyzing the information released by the official WeChat account of the People's Daily during the pandemic. The most-read COVID-19 information in China was summarized, and the factors that influence information dissemination were studied to understand the characteristics that affect its dissemination. Moreover, this was conducted in order to identify how to effectively disseminate COVID-19 information and to provide suggestions on how to manage public opinion and information governance during a pandemic. METHODS: This was a retrospective study based on a WeChat official account. We collected all COVID-19-related information, starting with the first report about COVID-19 from the People's Daily and ending with the last piece of information about lifting the first-level emergency response in 34 Chinese provinces. A descriptive analysis was then conducted on this information, as well as on Qingbo Big Data's dissemination index. Multiple linear regression was utilized to study the factors that affected information dissemination based on various characteristics and the dissemination index. RESULTS: From January 19 to May 2, 2020, the People's Daily released 1984 pieces of information; 1621 were related to COVID-19, which mainly included headline news items, items with emotional content, and issues related to the pandemic's development. By analyzing the dissemination index, seven information dissemination peaks were discerned. Among the three dimensions of COVID-19 information-media salience, content, and format-eight factors affected the spread of COVID-19 information. CONCLUSIONS: Different types of pandemic-related information have varying dissemination power. To effectively disseminate information and prevent the spread of COVID-19, we should identify the factors that affect this dissemination. We should then disseminate the types of information the public is most concerned about, use information to educate people to improve their health literacy, and improve public opinion and information governance.

Nitrogen budget at sediment-water interface altered by sediment dredging and settling particles: Benefits and drawbacks in managing eutrophication.

Internal nitrogen (N) loading of lakes is commonly controlled by sediment dredging, although its comprehensive effect on internal N loading remains unclear. Herein, we examined the long-term effects of sediment dredging on internal N loading from a new perspective on the N budget at the sediment-water interface (SWI) through a simulation of field dredging performed by incubating intact sediment cores from a shallow eutrophic lake (Lake Taihu). We further evaluated the role of settling particles (SP) in the recovery of N cycle processes after dredging and its potential impact on the N budget. Our results demonstrated that dredging could help reduce organic matter and total N in sediments; improve the redox environment of the SWI; slow down N mineralization, N fixation, denitrification, and anaerobic ammonia oxidation (anammox); and alter the N budget at the SWI and the contribution of various N cycle processes. However, the input of SP enriched in fresh organic matter and N could accelerate the recovery of N cycle processes at the SWI, reducing the variation in the N budget and the contribution of each N cycle process caused by dredging. Dredging significantly reduced the N flux at the SWI, which was evident from the reduction of inorganic N release flux and N removal through denitrification and anammox. Therefore, sediment dredging has its advantages and disadvantages in managing internal N loading in lakes. To maintain a long-term control on the release of internal N through sediment dredging, measures should be taken based on the in-lake and watershed to inhibit the inflow and settlement of particulate matter.

Does external phosphorus loading diminish the effect of sediment dredging on internal phosphorus loading? An in-situ simulation study.

Sediment dredging is an effective method to reduce internal phosphorus (P) loading of eutrophic lakes. However, external P loading may diminish the longevity of the effect of sediment dredging on P internal loading, and the mechanism of the same is unclear. Here, we used one-year in-situ simulation experiments to study the migration and transformation processes of P under the effect of external loading (suspended particle matter, SPM) input and internal loading control by dredging. The results showed that dredging can effectively reduce the internal loading and mobility of P, increase the P adsorption and retention capacity of the sediment, and improve the oxidation environment at the sediment-water interface (SWI), thus, inhibiting the release of internal P. The input of SPM, however, can significantly inhibit the above processes and increase the risk of P resupply and release. Temperature, dissolved oxygen, and the P resupply capacity (R) are the key factors affecting the P flux across the SWI. Therefore, it is necessary to control the input of SPM to effectively inhibit eutrophication after dredging. More measures to control the input of SPM, such as establishing buffer zones, ecological wetlands, and forebays, should be explored and applied.

Dredging method effects on sediment resuspension and nutrient release across the sediment-water interface in Lake Taihu, China.

Environmental sediment dredging is one of the most common methods for the remediation of contaminated sediments in lakes; however, debate continues as to whether the effectiveness of dredging methods contributes to this phenomenon. To determine sediment resuspension and nutrient release following dredging with a variety of dredging methods, four dredging treatments at wind speeds of 0-5.2 m/s were simulated in this study, namely suction dredging (SD), grab dredging (GD), ideal dredging with no residual sediments (ID), and non-dredging (ND). Field sediments from suction and grab dredging areas (including post-dredged and non-dredged sediments) of Lake Taihu were used to assess the release abilities of soluble reactive phosphorus (SRP) and ammonia nitrogen (NH4+-N) from the sediment-water interface. The effects of residual sediments on nutrient concentrations in water were also evaluated. The results reveal that inhibition of resuspension of particulate matter and nutrients released through sediment dredging decreases with increasing levels of residual sediment. Total suspended particulate matter content in the mean water columns of ID, SD, and GD under wind-induced disturbance (1.7-5.2 m/s) decreased by 67.5%, 56.8%, and 44.3%, respectively; total nitrogen and total phosphorus in ID (SD) treatments were 19.8% (12.9%) and 24.5% (11.2%) lower than that in ND treatment. However, there were ~ 1.6 and 1.5 times higher SRP and NH4+-N in the GD treatment compared with the ND treatment at the end of the resuspension experiment (0 m/s). A significant increase in the SRP and NH4+-N release rates at the sediment-water interface was also observed in field sediments from a grab dredging area, indicating that GD may pose a short-term risk of nutrient release to the water body. Hence, dredging methods with less residual sediments both during and after dredging improves the dredging quality.

Exchanges of nitrogen and phosphorus across the sediment-water interface influenced by the external suspended particulate matter and the residual matter after dredging.

Dredging is frequently implemented for the reduction of internal nitrogen (N) and phosphorus (P) loadings and the control of eutrophication. Residuals during dredging activities and external pollution loadings after dredging both commonly contribute to influence the effectiveness of dredging and have been widely discussed. In the current study, the exchanges of N and P across the sediment-water interface (SWI) to these two factors were compared in a six-month field incubation experiment. The results showed that the continuous deposition of external suspended particulate matter (SPM) led ammonium nitrogen (NH4+N) and soluble reactive phosphorus (SRP) fluxes across the newly formed SWI to increase by factors of 4.16 and 12.71, respectively, while residual material caused the same fluxes to increase by factors of 2.06 and 5.06. Both the deposition of external SPM and the residual matter led to higher increase of the fluxes of P across the SWI than those of the fluxes of N across the SWI after dredging. The SPM easily adsorbed P in the water due to extensive adsorption of water soluble organic matter (consisting primarily of easily-decomposed humic-like substances), iron, and aluminum. However, the decomposition of organic matter in the SPM after the deposition on the dredged sediment accelerated the dissolution of redox-sensitive P and organic P across the SWI after dredging. Both the increase in the fluxes of N and P across the SWI would further increase the concentrations of N and P in the overlying water and thereby aggravate the eutrophication status in lakes. More frequent dredging operations might be necessary to reduce the fluxes of N and P from the sediment due to the continuous influence of the external SPM and the residual matter.

In situ simulation of thin-layer dredging effects on sediment metal release across the sediment-water interface.

Dredging is widely applied to remediate contaminated sediments in aquatic ecosystems. However, the efficiency of thin-layer dredging for metal pollution control remains uncertain and even controversial. This study conducted an in-situ simulation experiment in Lake Taihu to investigate dredging effects on sediment metal release based on metal fractions, diffusion flux and kinetics parameters of metal resupply, using diffusive gradient in thin films (DGT), multi-microelectrode, and European Community Bureau of Reference (BCR) sequential extraction scheme. Results indicated that the exchange fluxes of metals did not necessarily correspond to total sediment metal concentrations or the contents of different sequentially-extracted metal fractions; there were appreciable decreases in Ni, Cd, Cu and Zn in terms of total sediment metal concentrations and metal fractions, whereas the bioavailability and release fluxes of labile Ni, Cu and Zn (but not Cd) were all notably promoted (by 136, 128 and 149%, respectively) in dredged area compared to those in un-dredged sediments. Further analysis on the kinetics of metal resupply by DGT technique and DGT-induced fluxes in sediments model (DIFS) showed higher concentrations of labile metals, with a larger resupply ability from sediments after dredging. Therefore, thin-layer dredging had the possibility to increase metal release from sediments to the water column. This was attributed to the remobilization of metal sulfides in anoxic deep sediments, as oxidation increased after dredging due to the introduction of oxygenated water, causing subsequent dissolution of sulfide-bound metals. In conclusion, dredging may not mitigate metal contamination, although it can reduce the total pollution load. Our findings indicated dual effects of dredging and provided new insights into the remobilization mechanism of metal release induced by dredging.

Nitrogen and Phosphorus Exchanges Across the Sediment-Water Interface in a Bay of Lake Chaohu.

A year-long field investigation was carried out in the most heavily polluted bay of Lake Chaohu to assess the temporal exchanges of ammonium nitrogen () and soluble reactive phosphorus (SRP) across the sediment-water interface (SWI) and to provide remediation advises. Results showed that the monthly average fluxes of and SRP were 31.38 and 6.98 mg m-2 d-1, respectively, both of which were higher than those in many other hyper-eutrophic lakes around the world. The exchanges of and SRP were both closed related to the oxygen penetration. Low oxygen penetration depth and generally negative oxygen uptake rates provoked the dissolution of redox sensitive phosphorus and labile in the sediment and increased the fluxes. In addition, the generally higher fluxes during late spring to autumn should be noted during the reduction of internal loadings, when applicable techniques should be implemented accordingly to achieve better reduction effects.

An investigation of the effects of capping on internal phosphorus release from sediments under rooted macrophytes (Phragmites australis) revegetation.

In eutrophic lake restorations, in situ capping is an often considered method to control sediment internal phosphorus (P) pollution for mitigating eutrophication status. Subsequent aquatic macrophyte revegetation can directly derive P from the sediment for growth. However, the effects of capping with clean soils on internal P release from sediments under rooted aquatic macrophyte revegetation are still unclear. In the present study, the influences of sediment P remobilization by P. australis revegetation on P inactivation by capping were investigated based on an entire growth simulation study. Our findings showed during the growth of P. australis, tests conducted on total phosphorous (TP), calcium-bound P (Ca-P), loosely bound P (loose-P), organic P (Org-P), and iron-adsorbed P (Fe-P) found significant changes (p < 0.001). Specifically, the mean contents of TP and Ca-P decreased by 291.1 and 224.2 mg kg-1, respectively, while those of Fe-P increased from 26.4 to 124.8 mg kg-1. In addition, sediment mobile-P contents increased coincidentally with the growth of P. australis during the whole course of experiment. Further analysis indicated calculated diffusion fluxes of soluble reactive phosphorus (SRP) generally increased with incubation time, although capping effectively induced the reduction of SRP concentration in pore water and its release to waters. Therefore, sediment P remobilization by P. australis revegetation was able to enhance P lability in lake sediments, with intermediate activation ability compared to other correlated water bodies. This phenomenon was most likely attributed to solubilization of sediment P by organic acids secreted from P. australis rhizosphere. Overall, sediment P remobilization by rooted macrophytes is unfavorable for capping to control internal P release to water column during eutrophic lake restorations.

Fraction distribution and leaching behavior of heavy metals in dredged sediment disposal sites around Meiliang Bay, Lake Taihu (China).

The objectives of this study were to characterize the heavy metal contamination status of surface soils sampled at two dredged sediment land disposal sites (the Baimao and Kongwan landfills) in Meiliang Bay, Lake Taihu, China, as well as to investigate the effect on their leaching behaviors due to acid rain. Among all the metals, only the nickel content in the Baimao landfill was higher than the Chinese reference value, and all metal contents were below the limit values for agricultural soils. The fraction distribution of metals by sequential extraction was similar at both sites. Cadmium had a relatively high proportion of exchangeable-carbonate fractions, while the other metals were mainly classified as residue fractions. The metals released from soils by simulated rainwater comprised less than 1% of the total soil metal content, and the effect of acid rain on heavy metal release from dredged sediments in land disposal sites was found to be negligible at both sites. All results indicate no environmental concern for the land disposal of dredged sediments and support the feasibility of beneficially reusing dredged sediment soils as a supplement to agricultural soils.

Nitrogen exchange across the sediment-water interface after dredging: The influence of contaminated riverine suspended particulate matter.

Dredging has been widely implemented in shallow lakes to reduce internal nitrogen (N) loading. The suspended particulate matter (SPM) coming from polluted rivers usually contains high levels of N and ultimately deposits on the dredged sediment surfaces near the river mouth. To study the influence of the riverine SPM on N exchange across the sediment-water interface (SWI) after dredging, a 360-day experiment was carried out comparing un-dredged and dredged sediments from Lake Chaohu, China. Dredged treatments showed a significant increase (p < 0.01) in total N concentrations in the sediments, while the deposition of SPM had little influence on labile NH4+-N concentrations. In addition, NH4+-N concentrations in pore-water and NH4+-N fluxes were significantly lower in dredged than in un-dredged sediments, despite the deposition of SPM. The oxygen production rates and the oxygen penetration depth in the dredged sediments were both higher than those in the un-dredged sediments. The increase of Nitrospira in dredged sediments was consistent with their decreased NH4+-N concentrations and fluxes across the SWI. Therefore, the oxidizing condition, increased oxygen production/consumption rates and Nitrospira relative abundance across the SWI were believed to be correlated with the low N exchange rates in dredged sediments. Dredging for reducing internal N loading in a river mouth area is therefore feasible, although the influence of the riverine SPM should be taken into account when aiming to achieve a long-term internal N loading reduction.