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This study focuses on the investigation of the variation mechanism of in situ generated calcium carbonate (CaCO3) during the simultaneous removal process of simulated sintering flue gas. The experiment was performed to investigate the synthetic removal behavior of SO2, NO2, and CO2under the simulated flue gas condition. Samples were obtained at different removal stages to characterize and analyze their compositions. The influence of in situ generated CaCO3and the effect of CO2on the process of desulfurization and denitrification are discussed. During the removal process, the pore structure of the sorbent is reshaping with fewer mesopores because of the products growing from pores. In situ generated CaCO3has desulfurization and denitrification effects. NO2also promotes the production of CaSO4, while the increasing and stable growth trend of nitrification products indicates that CO2and SO2have little effect on the formation of nitrification products, mainly relying on the absorption of NO2by the sorbent itself to generate calcium nitrate. At the end of the removal process, with the consumption of in situ generated CaCO3, more unreacted Ca(OH)2was exposed, allowing desulfurization and denitrification processes to continue until all the products cover the surface of the sorbent.

Coastal areas are important sites of environmental and socioeconomic activities and are significantly influenced by climate change. Here we analyzed the current and future responses of spatiotemporal characteristics of land‐sea thermal contrast (LSTC) along China's coastal zone to global warming. Using the European Centre for Medium‐Range Weather Forecasts Re‐Analysis (ERA)‐Interim and 18 Coupled Model Intercomparison Project 5 models, we find that the rate of global warming significantly influenced the LSTC in summer. The LSTC first decreased and then increased during the warming and hiatus periods, respectively. In winter, the LSTC decreased in the Bohai Sea coastal zone, Yellow Sea‐East China Sea coastal zone, and South China Sea coastal zone at rates of 0.46 (p< 0.01), 0.18 (p< 0.01), and 0.19 °C/decade, respectively. Spatially, the LSTC decreased in summer and winter with the decrease in latitude and increased in summer and winter with the decrease in longitude. These changes were caused by urbanization, land use changes, and topography. The spatial distribution was more strongly controlled by land than by sea. Meanwhile, the land/sea warming ratio was concentrated within the range of 0–1 and 1–2, and land/sea temperature variation trends commonly followed the same direction. Overall, land/sea surface temperature variations had similar amplitudes. Under three Representative Concentration Pathways (RCPs), the warming rate difference between land and sea in summer is small, but the land warms faster than the sea in winter, resulting in the LSTC decreasing fast in winter. Under RCP4.5 and RCP8.5, the linear trends in LSTC in Bohai Sea coastal zone, Yellow Sea‐East China Sea coastal zone, and South China Sea coastal zone ranged from 0.05 to 0.08 (p< 0.01) and 0.13 to 0.15 °C/decade (p< 0.01), respectively. Temporally, the warming hiatus significantly influenced the LSTC, as it first decreased and then increased during the warming and hiatus periods, respectivelySpatially, the distribution of LSTC was more strongly controlled by land than by sea in the coastal zoneIn future winter, the LSTC variation trends decreased significantly in China's coastal zone under RCP4.5 and RCP8.5

Based on the synergetic development of new industrialization, rapid urbanization and agricultural modernization (IUAM), and from the viewpoint of interactive relationships between water resources and regional population, eco-environment, economy and society, the concepts of water resources intensity (WRI), water environment intensity (WEI), water resources relative efficiency (WRRE) and water environment relative efficiency (WERE) are defined with reference to energy intensity, resources efficiency and environment efficiency theory. On the basis of benchmarking theory, the quantitative characterization and evaluation method of “Three Red Lines” (the upper limit of water resources allocation, the baseline of utilization efficiency of water resources and the upper limit of sewage discharge) is proposed. According to these concepts and models, an empirical analysis of the Three Red Lines of water resources on the Chinese mainland between 2003 and 2012 was carried out. The results showed that total water consumption in eastern, central and western parts of China possesses “club convergence” characteristics, which means these areas have similar internal conditions appeared convergence in the development. Inter-provincial differences in water consumption continue to decrease, but the north–south differentiation characteristics in the eastern and central regions were still relatively obvious, while provincial differences in the eastern part were at a minimum and the central region had the largest. Water Resources Efficiency (WRE) of all four sectors in the Southwest rivers and Huaihe River basins were generally high. Industrial WRRE in the Songhua River, Yangtze River and Pearl River basins, agricultural WRRE in the Songhua River, Yellow River and northwestern river basins and domestic WRRE in the Liaohe River, Yangtze River and Pearl River basins were all low. Eco-environmental WRRE in the southeastern rivers and Yangtze River basins were low but showed an upward trend. Other river basins, except for the Northwestern rivers basin, had high eco-environmental WRRE with a downward trend. Western China, especially the northwestern part, had a low relative intensity of the water environment (WERI) and high integrated water environment management (IWEM) performance, but the relative intensities of the water resources (WRRI) were fairly high, and the comprehensive performance of integrated water resources management (IWRM) in these regions was low. In southern China, especially the southeastern part, the IWEM was fairly high, but the overall IWRM was lower.

The East Siberian Continental Margin is a major constituent of the western Arctic Ocean, ideal for studying the evolutionary history of the Siberian Ice Sheet (SIS) based on its unique geographical location and medium‐depth bathymetry. For this study, the sedimentary core CHINARE‐ARC07‐E25 (E25) was analyzed, revealing nearly continuous stable oxygen isotope and mineralogy records that preserved scenarios of the SIS development. Lithostratigraphic evidence suggests that the stratigraphic range of E25 extends to marine isotope stage (MIS) 7. Stable oxygen isotope analysis reveals multiple strong, light‐oxygen isotopic excursions since the penultimate glacial, accompanied by multiple patterns of ice rafted debris content and mineralogy. Based on these isotopic events, the potential factors causing the excursions and the provenance of drainage were evaluated. It was found that the excursion events recorded in pink‐white carbonate detritus layers could be related to the retreat of the Laurentide Ice Sheet. The most typical events, occurring during the deglaciation periods of MIS6/5e and MIS4/3 to early MIS3, were characterized by involving a mixture of two or more sources, and could be used to trace the activity of the SIS, which has been ignored in previous studies. Findings of this study are expected to advance the understanding of SIS contribution to the western Arctic Ocean basin development, which is important for interpreting global climate change behavior of similar ice sheets in the Arctic region. Several large ice sheets in the Arctic Ocean formed during the Late Pleistocene, which had a profound impact on the global climate. Recently published geophysical evidence shows that huge glaciers have repeatedly developed on the East Siberian Continental Margin, and they were proposed to have comprised the Siberian Ice Sheet (SIS). However, the contribution of the SIS has been ignored in previous studies of the western Arctic Ocean. In this study, a sediment core was collected from the medium‐depth bathymetry Mendeleev Ridge to ensure a sample that was not directly affected by glaciation erosion. Repeated freshwater events, identified based on significant light‐oxygen isotopic excursion and coarse fraction content peaks, were evaluated and analyzed for mineralogical composition to reflect their provenances. The results show that the freshwater events recorded in the Mendeleev Ridge sediments show strong and mixed‐provenance inputs, while an increase in plagioclase, illite, and chlorite during deglaciation may indicate the contribution of the SIS. This not only suggests that the SIS was a potential source of freshwater of the Arctic Ocean, but also provides evidence of its earlier expansion (MIS6), in addition to new perspectives for evaluating the ice sheet activities and corresponding paleoenvironmental changes. Stable oxygen isotope and mineralogy were studied in sediment cores from the Mendeleev Ridge, Arctic Ocean, covering ∼220 kaIsotopic and mineralogical records could trace sources of glacial input during the late Quaternary, mainly from Eurasia and North AmericaThe Siberian ice sheet is determined to be a significant and independent potential freshwater provenance of the western Arctic Ocean Stable oxygen isotope and mineralogy were studied in sediment cores from the Mendeleev Ridge, Arctic Ocean, covering ∼220 ka Isotopic and mineralogical records could trace sources of glacial input during the late Quaternary, mainly from Eurasia and North America The Siberian ice sheet is determined to be a significant and independent potential freshwater provenance of the western Arctic Ocean

In this study, we collected gas, particulate, and surface water‐dissolved phase samples from 16 sites in the South China Sea from March 21 to April 12, 2018. Thereafter, all the samples were analyzed for the air‐water exchange and source apportionment of polycyclic aromatic hydrocarbons (PAHs). Thus, it was observed that the overall PAH concentrations in the water and gas phases were 8.0 ± 5.5 ng/L and 41.3 ± 24.7 ng/m3, respectively. Back trajectory simulation showed that the air masses in the South China Sea primarily originated from mainland China during the heating period, and air‐water exchange analysis showed net deposition from air to water, with fluxes ranging from −5.53 to −89.72 ng/m2/d. Further, the logarithmic gas‐particle partitioning coefficient (logKp) of the PAHs regressed linearly with the logarithmic subcooled liquid vapor pressure (log P0 L), with an average slope of −0.3 ± 0.13. We found a net deposition trend from air to water, which is different from the trends in other marginal seas of ChinaNortheastern China was the main source of polycyclic aromatic hydrocarbons (PAHs) in the air masses in this season, and PAHs were carried mainly by gas phase We found a net deposition trend from air to water, which is different from the trends in other marginal seas of China Northeastern China was the main source of polycyclic aromatic hydrocarbons (PAHs) in the air masses in this season, and PAHs were carried mainly by gas phase

River‐dominated marginal seas are important carbon sinks on Earth. However, their carbon sequestration capacities are changing due to increased anthropogenic perturbations. Herein, we employ substantial datasets to study the characteristics of organic carbon (OC) from the East China Sea (ECS) in 2006 and 2018 and reveal the impacts of reservoir construction on the OC deposition in this region. We show that the distribution of sedimentary OC in the ECS is primarily controlled by riverine input and seabed erosion processes. Hydrodynamic processes influence the OC deposition due to both the scouring of fine‐grained sediments and selective degradation of OC associated with the sediment mobilization. The deposition flux of OC in the ECS decreased by 48% after reservoir construction. These findings demonstrate that reservoir construction seriously affected the OC deposition in the ECS and may be applicable to river‐dominated continental shelves worldwide. Reservoir construction changed the transport process and deposition pattern of organic carbon in the East China SeaThe deposition flux of organic carbon in the East China Sea decreased by 48% due to reservoir constructionDeposition flux reduction threatens river‐dominated margins worldwide and should be taken seriously

Under the combined impacts of natural changes and human activities, the past, current, and future marine heatwaves (MHWs) in China's marginal seas and adjacent offshore waters (CMSOW) need a comprehensive understanding. This study provides a systematic analysis of the spatiotemporal variations using daily sea surface temperature data and simulates the future trend using 12 climate models. During 1982–2018, the mean annual total days, duration, frequency, and mean intensity of the MHWs in the CMSOW increased by 20–30 days/decade, 5–9 days/decade, 1–2 decade−1, and 0.1–0.3°C/decade, respectively (p<0.01). The maximum sea surface temperature anomalies in the Bohai Sea was over 6–8°C, and the MHW's frequency, duration, and mean intensity were higher than twice the global average, which could have impacted fishery resources and occurrence of harmful algal blooms. The variations of the MHWs in the CMSOW result from the robust ocean surface warming, which is caused by increased solar radiation due to reduced cloud cover, reduced ocean heat loss from weaker wind speed, weakening but warmer Kuroshio, and strong El Niño. In the future, the areas with longer total days and duration will increase; the spatial pattern of frequency has a negative relationship with that of duration while that of mean intensity is mostly unchanged. Year 2040 is a key node for the future changes of MHW under different Representative Concentration Pathways. The trend of total days increases from fast to slow, and frequency shows an opposite trend; the duration and mean intensity rise faster after 2040. The Bohai Sea, Japan Sea, Beibu Bay, and east of Taiwan Island have the highest mean annual total daysSevere MHWs in the Bohai Sea could have impacted fishery resources and occurrence of harmful algal bloomsIn the future, 2040 is a key node for the future changes of MHW under different RCPs

Distribution patterns of PAHs changed drastically due to human‐induced catchment changesDepositional center of PAHs in the ECS transferred southwardRiver‐dominated margins will face this threat worldwide Human‐induced changes in river catchments, such as damming, can affect estuarine depositional settings and further affect the transport of sediments and associated pollutants. Polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the East China Sea (ECS) at two time nodes (2006 and 2018) were compared to understand the response of PAHs to human‐induced catchment changes. PAH concentrations in the ECS ranged from 8–414 ng g−1(dry weight), with a mean value of 112 ± 77 ng g−1, relatively low than that in 2006 (38–308 ng g−1, with a mean of 122 ± 60 ng g−1). Sharp decreases in sediment loads have triggered erosion in subaqueous delta and changed the distribution of sediment components, which may eventually influence the distribution pattern of PAHs. The obvious spatial differentiation of PAHs between 2006 and 2018 suggested that the depositional center of PAHs shifted from the estuary to the inner shelf area. PAH deposition patterns in the ECS were primarily influenced by riverine input before 2006 but are now dominated by winnowing processes related to long‐distance transport due to sharply decreased sediment loads. Dam construction in the river catchment intercepted large amounts of sediments and PAHs, shifting the Changjiang‐derived PAH depositional center from the ocean to reservoirs. Overall, depositional patterns of PAHs in the ECS were largely altered by human‐induced catchment changes, which may cause significant impacts on the region's biogeochemical cycles and ecosystem health. Coastal oceans are usually considered important sinks of terrestrial materials, especially river‐dominated coastal margins. However, river‐derived terrestrial materials have decreased drastically in the last several decades worldwide, due to intensified human activities that have changed the local sedimentary environment. In this study, changes in the surface sediment grain size within the East China Sea from 2006 to 2018 indicated that the sedimentary environment in this region was clearly altered. Similarly, the distributions and compositions of PAHs in surface sediments changed from 2006 and 2018. Based on combined analysis of grain size and PAHs, we found that PAH dynamics in this region were primarily influenced by riverine inputs before dam construction in the Changjiang (Yangtze) River basin but are now dominated by winnowing processes related to long‐distance transport due to sharply decreased sediment loads. Therefore, intensified human‐induced catchment changes have significant influenced the fate of PAHs in the East China Sea.