Environmental threats induced heavy ecological burdens on the coastal zone of the Bohai Sea, China

Anthropogenic activity shapes the assemble and co-occurrence pattern of microbial communities in fishing harbors around the Bohai Economic Circle

This study aimed to elucidate the effects of coastal environmental stress on the composition of sediment bacterial communities and their cooccurrence patterns in fishing harbors around the Bohai Economic Circle, China. Compared with the natural sea area, fishing harbors contained higher levels of organic pollution (organic pollution index = 0.12±0.026) and considerably reduced bacterial richness and evenness. The distributions of sediment microbial communities clustered along the pollutant concentration gradients across fishing harbors. Betaproteobacteria dominated (76%) organically polluted fishing harbors, which were mostly disturbed by anthropogenic activities. However, the harbors also revealed the absence of numerous pathogenic (Coxiella and Legionella) and photosynthetic (Synechococcus and Leptolyngbya) bacteria. Abundant genera, including Thiobacillus and Arenimonas, exhibited a positive correlation with total phosphorus and a negative correlation with total nitrogen in sediments. Meanwhile, Sulfurovum, Psychrobacter, and Woeseia showed the opposite trend. Pollutant accumulation and anthropogenic activities caused the decrease in the sediment microbial diversity and dispersal ability and promoted convergent evolution. Severely polluted harbors with simplified cooccurrence networks revealed the presence of destabilized microbial communities. In addition, the modularity of bacterial networks decreased with organic pollution. Our results provide important insights into the adjustment mechanism of microbial communities to community organization and functions under environmental pollution stress. Overall, this study enhanced our understanding of how microbial communities in coastal sediments adapted and survived amidst anthropogenic activities like oily effluent discharges from large ships, wash water, domestic sewage, garbage, and fisheries wastes. It also examined their resilience to future contamination.

Phosphorus depletion is exacerbated by increasing nitrogen loading in the Bohai sea

Phosphorus (P) is an essential nutrient for algal growth in nearshore ecosystems. In recent years, there has been a shift in nutrient dynamics in nearshore areas, leading to an exacerbation of P limitation, although the underlying mechanisms remain unclear. This study analyzed the P species and budget in the Bohai Sea (BS) from 2011 to 2020, aiming to explore the intrinsic mechanisms of P limitation in the BS. The results show that the main external source of P in the BS was river transport (89%), and the primary fate of P was burial (96%) into the sediment. Due to excessive nitrogen (N) input and biological processes in the BS, the P budget in the BS is unbalanced, resulting in an increase in the N/P ratio, particularly in nearshore areas. Nearshore areas typically have lower concentrations of dissolved inorganic P (DIP) in the water and higher concentrations of reactive P (Reac-P) in the sediments. This pattern is particularly evident in Bohai Bay and the northwest nearshore region, where harmful algal blooms occur frequently. To cope with enhanced P limitation, the biologically driven P regeneration and cycling processes within the BS are accelerated. From 2011 to 2020, the concentration of DIP in the BS during autumn increased, while the content of Reac-P in sediments slightly decreased. Historical data indicate that P depletion in the BS is intensifying and expanding, primarily due to N enrichment and algal production. N enrichment alters the structure and composition of primary production, potentially exacerbating P depletion in the BS. Excessive N may have significant impacts on the P pool, potentially influencing the stability of future coastal ecosystems.

Evaluating the effectiveness of coastal environmental management policies in China: The case of Bohai Sea

With marine pollution issues becoming serious and widespread, a series of coastal environmental managemental policies are being carried out worldwide, the effectiveness of which requires comprehensive evaluation. Taking the Bohai Sea (BS) of China as an example, which has been plagued by serious ecological and environmental issues for decades due to terrestrial pollution discharge, this study explored and quantified, for the first time to our best knowledge, the variability of water quality after initiating a dedicated 3-year pollution control action (Uphill Battle for Integrated Bohai Sea Management, UBIBM, 2018-2020) implemented by China's central government, with two water quality indexes of water color (Forel-Ule index, FUI) and transparency (Secchi disk depth, Z_SD, m) from satellite observations. During the UBIBM, a significant improvement in water quality was detected, characterized by a clearer and bluer BS, with Z_SD and FUI improved by 14.1% and 3.2%, respectively, compared with the baseline period (2011-2017). In addition, an abrupt drop in the long-term record (2011-2022) of the coverage area of highly turbid waters (Z_SD≤2 m or FUI≥8) was found in 2018, which coincided with the start of the UBIBM, indicating that the water quality improvement may be attributed to the pollution alleviation of the UBIBM. Independent data of land-based pollution statistics also supported this deduction. (3) Compared with the previous two pollution control actions in the first decade of 21st century, UBIBM was proved to be the most successful one in terms of the achieved highest transparency and lowest FUI during the past two decades. Reasons for the achievement and implications to future pollution control are discussed for a more sustainable and balanced improvement in the coastal environment. This research provides a valuable example that satellite remote sensing can play a vital role in the management of coastal ecosystems by providing effective evaluation of pollution control actions.

New insights into the bioremediation of petroleum contaminants: A systematic review

Petroleum product is an essential resource for energy, that has been exploited by wide range of industries and regular life. A carbonaceous contamination of marine and terrestrial environments caused by errant runoffs of consequential petroleum-derived contaminants. Additionally, petroleum hydrocarbons can have adverse effects on human health and global ecosystems and also have negative demographic consequences in petroleum industries. Key contaminants of petroleum products, primarily includes aliphatic hydrocarbons, benzene, toluene, ethylbenzene, and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), resins, and asphaltenes. On environmental interaction, these pollutants result in ecotoxicity as well as human toxicity. Oxidative stress, mitochondrial damage, DNA mutations, and protein dysfunction are a few key causative mechanisms behind the toxic impacts. Henceforth, it becomes very evident to have certain remedial strategies which could help on eliminating these xenobiotics from the environment. This brings the efficacious application of bioremediation to remove or degrade pollutants from the ecosystems. In the recent scenario, extensive research and experimentation have been implemented towards bio-benign remediation of these petroleum-based pollutants, aiming to reduce the load of these toxic molecules in the environment. This review gives a detailed overview of petroleum pollutants, and their toxicity. Methods used for degrading them in the environment using microbes, periphytes, phyto-microbial interactions, genetically modified organisms, and nano-microbial remediation. All of these methods could have a significant impact on environmental management.

Development and evaluation of a GPU-based coupled three-dimensional hydrodynamic and water quality model

In this study, a graphics processing unit (GPU)-based three-dimensional coupled hydrodynamic and water quality numerical model (GPUOM-WQ) was developed for the first time, which introduces pollution sources of atmospheric deposition, aquaculture wastewater, and oil platform emission to describe marine pollution comprehensively. A test case with analytical solutions and a real case with measured data were used to validate the accuracy of GPUOM-WQ. Simulation results indicate that the maximum error between the numerical and analytical solutions is 0.9 %, and the average relative error between simulated and measured values of 5 water quality variables at 38 stations in spring, summer, fall and winter is 14.63 %. In the real case simulation, GPUOM-WQ accelerates the computation 62.48 times, which is 3.23 times faster than in 64-core central processing unit (CPU) parallel mode. This study makes it possible to accurately simulate the marine water quality variation and spatiotemporal distribution in a high-resolution and efficient way.

Changes in Sources and Composition of Beach Waste in Coastal Cities around the Bohai Sea of China during the Tourist Peak and Off-Peak Seasons

Beach waste is an important pollutant in the Bohai Sea and coastal cities around the Bohai Sea and has raised many social and environmental concerns in China. The semi-closed characteristics of the Bohai Sea, the well-developed tourism, the special industrial structure and residents' living habits endow the beach waste around Bohai sea with a unique character that should be explored. This study investigated changes in the sources and composition of beach waste in coastal cities around the Bohai Sea of China during the tourist peak and off-peak seasons. Beach waste from twenty beaches in thirteen coastal cities around the Bohai Sea was sampled and analyzed in March and August 2021, respectively. The results showed that beach waste around the Bohai Sea was characterized by large quantities and small weights and was greatly affected by human coastal activities. The sources and composition of beach waste from different coasts and different seasons varied, whereas the overall trend was consistent. In terms of composition, beach waste in both the tourist peak season and off-peak season was mainly composed of plastics, fabrics and paper, which accounted for more than 70% of the total in weight. Meanwhile, the proportion of plastics in the total quantity of beach waste was greatest (maximum of up to 71%) and exhibited seasonal fluctuations, trending higher in the tourist peak season than in the off-peak season. In contrast, trends in the proportion of paper and fabrics in the total quantity and total weight of beach waste were relatively stable in different seasons. In terms of sources, beach waste mainly derived from human coastal activities, the proportion of which in the total quantity of beach waste in the tourist peak season reached 70.55% and was 11% higher than that in the tourist off-peak season. Shipping/fishing activities were the second largest source of beach waste, and their proportion in the total quantity of beach waste in the tourist peak season was 5% lower than that in the tourist off-peak season, as the tourist peak season around the Bohai Sea coincides exactly with the fishing moratorium. The quantity of smoking-related waste only accounted for 9.35% and 7.73% of beach waste in the tourist peak and off-peak seasons, respectively. The special semi-enclosed structure of the Bohai gulf, surrounded by land on three sides, aggravated the accumulation of beach waste on the coast. Source reduction and classified recovery, collaborative management of marine waste and beach waste, and joint prevention and control mechanisms of three provinces (Liaoning, Hebei and Shandong) and one municipality (Tianjin) were suggested for comprehensive management of beach waste in coastal cities around the Bohai Sea of China. This study provided valuable information for beach waste management in coastal cities around the Bohai Sea of China.

PSR-FCCLP model based total maximum allocated loads optimization of TN and TP in Bohai Bay

Eutrophication is a global problem for coastal ecosystems, one that Bohai Bay, China, has been severely afflicted due to rapid economic and social development in the past decades. It was urgent to manage the total maximum allocated loads (TMALs) of the total nitrogen (TN) and total phosphorus (TP) on land-based, which was closely related to coastal eutrophication. In this study, from the perspective of economy-resources-environment (ERE) system, we presented the fuzzy credibility constrained linear programming based on pressure-state-response (PSR-FCCLP) model, which calculated the TMALs of TN and TP at three credibility levels (λ = 0.55, 0.75, and 0.95) in Bohai Bay. The results showed that when the credibility level increased from 0.55 to 0.95, the TMALs of TN and TP would decrease from 13,573.38 t/a to 12,820.00 t/a and from 2665.58 t/a to 2514.90 t/a, respectively. This study will provide support for environmental management in coastal regions.

Ecological risk assessment of heavy metal pollutants and total petroleum hydrocarbons in sediments of the Bohai Sea, China

Heavy metals and organic pollutants like total petroleum hydrocarbons (TPHs) in coastal marine sediments are receiving extensive attention, as they may pose a serious threat to the aquatic environment and ecosystem health. To date, however, data on the long-term variations in the levels of sedimentary heavy metals and TPHs as well as their ecological risks are relatively limited. Here, we conducted 12 cruises spanning 3 years in the Bohai Sea and obtained ~1400 sediment samples to explore the long-term variations of heavy metals (i.e., Hg, As, Cu, Zn, Pb, Cd) and TPHs, and to assess their potential ecological risks. The results suggested that the ranges for the levels of Hg, As, Cu, Zn, Pb, Cd, and TPHs in sediments between 2019 and 2021 were <0.01-0.07, 0.23-10.72, 8.07-20.67, 25.52-46.55, 10.94-28.19, 0.14-0.56, and 9.14-18.41 mg kg^-1, respectively. Based on the single factor evaluation (F_i) for sediment quality, we found that most of the evaluation factors in the study area met the requirements of sediment quality standard (i.e., F_i < 1), except for the factor of metal Cd in some cases. The implication is that the sediment in the Bohai Sea was fairly clean in terms of heavy metals and TPHs. However, the concentration of metal Cd exceeded the sediment quality standard during May 2019 and 2020 (i.e., F_i > 1), indicating that Cd could be identified as a major pollutant in surface sediments. Also, based on the ecological risk assessment (E_i) of heavy metal pollutants, we found that the metal Cd had reached a level with potential ecological risk in some cases (80 ≤ E_i < 160). As such, we further suggested that the Cd contamination might have a potential risk on the Bohai Sea' ecosystem.

Uncertainty or trust? Political trust, perceived uncertainty and public acceptance of personal carbon trading policy

Achieving carbon neutrality has become a global consensus, and plenty of measures and policies have been proposed in various industries to obtain this ambitious goal. As an innovative and radical environmental policy tool, personal carbon trading (PCT) policy which aims to reduce carbon emissions from the private consumption sector has aroused the attention. For a new policy tool, public support and acceptance is critical to obtain policy legitimacy and policy implementation. To implement PCT policy smoothly, the current research aims to explore the antecedents of public acceptance. From the emotional reaction perspective, this research mainly evaluated how political trust, perceived uncertainty and associated emotions matter for public acceptance of PCT policy. Based on the survey data, this research revealed that political trust has a direct positive impact on public acceptance of PCT policy. Meanwhile, political trust also has an indirect impact on public acceptance of PCT policy via emotions. Specifically, political trust is positively associated with positive emotions and negatively associated with negative emotions. Positive emotions promote public to accept PCT policy, while negative emotions inhibit public to accept PCT policy. The negative emotions exert a more powerful impact on public acceptance than positive emotions. Additionally, we found that perceived uncertainty exerts a negative effect on public acceptance and negatively regulates the relationship between political trust and public acceptance. That is, perceived uncertainty has a significant substitution effect on political trust. According to the research findings, policy implications to improve public acceptance of PCT policy were explored.

Temporal and spatial variation, input fluxes and risk assessment of cyclic methylsiloxanes in Rivers-Bohai Sea System

In the present study, the total concentrations of three cyclic methylsiloxanes (ΣCMSs), including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), in surface water and sediment samples of five main rivers draining into the Bohai Sea were in the range of 1.62-1.39 × 10³ ng/L and 1.92-1.69 × 10³ ng/g dw, respectively. Riverine input had great influence on the coastal distribution of siloxanes in the Bohai Sea. The concentrations of ΣCMSs in coastal sediments farthest away (40-50 Km) from the estuaries were only 4-33% of those close to the estuaries. But surprisingly, compared with those in coastal sediments (1.03-1.44 × 10³ ng/g dw), the concentrations of CMSs (1.56-2.67 × 10³ ng/g dw) in some deep-sea sediments were higher, and certain positive correlation existed between sediment ΣCMSs in this area with the total petroleum hydrocarbons concentration (R² = 0.92, p < 0.05) suggested offshore oil exploitation as one important emission source of siloxanes. Overall, calculated based on their sediment concentrations, D4-D6 had negligible ecological risks to the benthic organisms in river-Bohai Sea system, i.e. HQs < 1. However, sediment-accumulation of siloxanes should be paid attention, especially for some deep-sea sediments nearby drilling platforms, where it will take only less than 1 year for D4 to reach its threshold.

Strategies of dispersive liquid-liquid microextraction for coastal zone environmental pollutant determination

Coastal zone means the interface of land and sea, and therefore, environmental pollutants steaming from land-based activities (like manufactories) and sea-based activities (like shipping) are all existing in coastal zone. These pollutants usually have characteristics of low residues, complicated matrices, easy accumulation and so on, causing difficulty to detect coastal pollutants quickly and sensitively. It is imperative to perform effective sample preparation prior to instrumental analysis. Dispersive liquid-liquid microextraction (DLLME) has attracted significant research interest for sample preparation, owing to its high enrichment ability, low reagent/sample consumption, and wide analyte/matrix applicability, as well as robustness, simplicity, rapidity and inexpensiveness. Herein, we comprehensively review the recent advancements of DLLME technology and its analytical parameters including enrichment principles, extraction modes, and practical application; the emphasis is on novel mode-construction and representative coastal-environmental pollutants extraction. Construction strategies are highlighted by classifying DLLME into five major modes, according to extractant's types, including normal ones, low density solvents, ionic liquids, deep eutectic solvents and others. The coupling of DLLME with other extraction techniques like solid-phase extraction is also briefly introduced. The strengths and weaknesses of each strategy and its rationality are also elaborated. In addition, some typical applications of the different DLLME modes for the determination of organic compounds and heavy metals in coastal water, sediment, soil, and biota are summarized. The increasingly concerned green aspects and instrumentation of DLLME are presented, and finally, the challenges and perspectives of the DLLME for environmental analysis are proposed.

Quantifying the Contributions of Environmental Factors to Wind Characteristics over 2000–2019 in China

Global climate change and human activities have resulted in immense changes in the Earth’s ecosystem, and the interaction between the land surface and the atmosphere is one of the most important processes. Wind is a reference for studying atmospheric dynamics and climate change, analyzing the wind speed change characteristics in historical periods, and studying the influence of wind on the Earth-atmosphere interaction; additionally, studying the wind, contributes to analyzing and alleviating a series of problems, such as the energy crisis, environmental pollution, and ecological deterioration facing human beings. In this study, data from 697 meteorological stations in China from 2000 to 2019 were used to study the distribution and trend of wind speed over the past two decades. The relationships between wind speed and climate factors were explored using statistical methods; furthermore, combined with terrain, climate change, and human activities, we quantified the contribution of environmental factors to wind speed. The results show that a downward trend was recorded before 2011, but overall, there was an increasing trend that was not significant; moreover, the wind speed changes showed obvious seasonality and were more complicated on the monthly scale. The wind speed trend mainly increased in the western region, decreased in the eastern region, was higher in the northeastern, northwestern, and coastal areas, and was lower in the central area. Temperature, bright sunshine duration, evaporation, and precipitation had a strong influence, in which wind speed showed a significant negative correlation with temperature and precipitation and vice versa for sunshine and evapotranspiration. The influence of environmental factors is diverse, and these results could help to develop environmental management strategies across ecologically fragile areas and improve the design of wind power plants to make better use of wind energy.

Enhancing the Oil-Fouling Resistance of Polymeric Membrane Ion-Selective Electrodes by Surface Modification of a Zwitterionic Polymer-Based Oleophobic Self-Cleaning Coating

Due to the frequent oil spill accidents and pollution of industrial oily wastewater, oil fouling has become a great challenge to polymeric membrane ion-selective electrodes (ISEs) for applications in oil-contaminated areas. Herein, a simple approach is proposed to enhance the oil-fouling resistance of polymeric membrane ISEs by surface modification of a zwitterionic polymer-based underwater oleophobic coating. As a proof-of-concept, a classical poly(vinyl chloride) membrane-based calcium ion-selective electrode (Ca²⁺-ISE) is chosen as a model sensor. The zwitterionic polymer-based coating can be readily modified on the sensor's surface by immersion of the electrode into a mixture solution of dopamine and a zwitterionic acrylate monomer (i.e., sulfobetaine methacrylate, SBMA). The formed poly(SBMA) (PSBMA) coating alters the oleophilic membrane surface to an oleophobic one, which endows the surface with excellent self-cleaning properties without loss of the sensor's analytical performance. Compared to the pristine Ca²⁺-ISE, the PSBMA-modified Ca²⁺-ISE exhibits an improved analytical stability when exposed to oil-containing wastewater. The proposed approach can be explored to enhance the oil-fouling resistance of other polymeric membrane-based electrochemical sensors for use in the oil-polluted environment.