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Recurrent green tide has been widely studied due to its severe damage to coastal ecosystem. Jinmeng Bay, a popular resort in northeastern China, has suffered from green tide events since 2015, after the constructions of artificial islands and submerged reefs. To investigate the potential impacts of artificial islands and reefs on the water quality in Jinmeng Bay, a MIKE 21 numerical model was established by coupling a hydrodynamic model with a transport model of Chemical Oxygen Demand (COD) and nitrate ion (NO3−). The changes in the water quality in Jinmeng Bay by the initial, first-stage and current construction conditions of artificial islands and submerged reefs were simulated. The model results indicated that: (1) The artificial islands and reefs in Jinmeng Bay hinder the tidal currents and weaken the tidal actions. (2) The weakened tidal actions at the estuary lead to the accretion of COD and NO3−. The neap tides generate a littoral zone with the high concentration of COD and NO3−, and the spring tides maintain the zone at the estuary. (3) NO3− is more sensitive than COD to the variation of hydrodynamic conditions. The NO3− concentration in the north of Conch artificial island is altered significantly, where the construction of the artificial structures decrease the concentration by ~30%, while the demolition of the connection road increases the concentration beyond its initial values by 16~21%. (4) Under the current construction conditions, the rising concentrations of COD (up to 2%) and NO3− (up to 40%) increase the frequency and scale of green tides in Jinmeng Bay considerably. Therefore, continuous monitoring of water quality is required for this region. [ABSTRACT FROM AUTHOR]

Qinhuangdao, a famous coastal resort city in northeastern China, has been affected by the rapid growth of harmful algae. The brown tide induced by Aureococcus anophagefferens (A. anophagefferens) first occurred along Qinhuangdao's coastline in 2009, and it then developed into a harmful alga for the Bohai Sea. Based on MIKE 21, we construct a 2D coupled hydrodynamic and transport model to study the variation and distribution of total nitrogen (TN), and establish the relationship between A. anophagefferens, dissolved organic nitrogen (DON), and TN to provide a fast forewarning system for brown tide in Qinhuangdao. This model considers the decay, diffusion, and settling of TN, and the model results are in good agreement with the measured tidal level, current, and TN, indicating that the model is capable of capturing the observed TN distribution during the brown tide period. The transfer function relating TN to A. anophagefferens leads to a reliable fast forewarning and monitoring system. Moreover, the transferred A. anophagefferens cell density can be used to forecast the regional risk level of brown tide with a specific color indicator. The implementation of national policy relating to marine ecosystems decreases the nearshore concentration of N, P, and other nutrients, and therefore decreases harmful algal blooms. The fast routine assessment of brown tide by the present warning system provides robust guidance for the government to take action. [ABSTRACT FROM AUTHOR]

Beach nourishment, a common practice to replenish an eroded beach face with filling sand, has become increasingly popular as an environmentally friendly soft engineering measure to tackle coastal erosion. In this study, three 200 m long offshore submerged sandbars were placed about 200 m from the shore in August 2017 for both coastal protection and beach nourishment at Shanhai Pass, Bohai Sea, northeastern China. A series of 21 beach profiles were collected from August 2017 to July 2018 to monitor the morphological changes of the nourished beach. Field observations of wave and tide levels were conducted for one year and tidal current for 25 h, respectively. To investigate the spatial-temporal responses of hydrodynamics, sediment transport, and morphology to the presence of three artificial submerged sandbars, a two-dimensional depth-averaged (2DH) multi-fraction sediment transport and morphological model were coupled with wave and current model and implemented over a spatially varying nested grid. The model results compare well with the field observations of hydrodynamics and morphological changes. The tidal range was around 1.0 m and the waves predominately came from the south-south-east (SSE) direction in the study area. The observed and predicted beach profiles indicate that the sandbars moved onshore and the morphology experienced drastic changes immediately after the introduction of sandbars and reached an equilibrium state in about one year. The morphological change was mainly driven by waves. Under the influences of the prevailing waves and the longshore drift toward the northeast, the coastline on the leeside of the sandbars advanced seaward by 35 m maximally while the rest adjacent coastline retreated severely by 44 m maximally within August 2017–July 2018. The model results demonstrate that the three sandbars have little effect on the tidal current but attenuate the incoming wave significantly. As a result, the medium-coarse sand of sandbars is transported onshore and the background silt is mainly transported offshore and partly in the longshore direction toward the northeast. The 2- and 5-year model simulation results further indicate that shoreline salient may form behind the sandbars and protrude offshore enough to reach the sandbars, similar to the tombolo behind the breakwater. [ABSTRACT FROM AUTHOR]

To develop the blue economy, one of the most critical factors is ocean space. Marine-related industries, such as offshore wind power, marine fishery, shipping and offshore oil, compete in near-shore and offshore space. The marine spatial planning is crucial for the development of these industries. The first Chinese pilot and commercial offshore wind projects were put into operation in 2007 and 2010 respectively. In the past decade, China's offshore wind power industry has experienced very high growth rates. According to the statistics of World Wind Energy Council, the installed capacity of China's offshore wind power reached 2790MW in 2017, accounting for 14.83% of the global capacity and ranking third after United Kingdom (36.33%) and Germany (28.46%). It is estimated that the development of China's offshore wind power industry will accelerate, and play a more important role in the transition to a low-carbon, sustainable energy system. The main objective of this paper is to study the spatial distribution and its evolution of China's offshore wind industry. It is organized as follow. Firstly, based on the latest data, the development of China's offshore wind power industry, including the existing, under construction projects, spatial distribution and the latest plan, has been reviewed. Secondly, it discusses the evolution of the spatial planning, the industry distribution, competition among marine industries and the coordination of government's departments. Thirdly, the underlying causes of the rapid and extensive expansion of offshore wind industry are studied. Finally, some policy recommendations are provided for the healthy and sustainable development of China's offshore wind power industry from the perspective of spatial planning. [ABSTRACT FROM AUTHOR]

Utilizing the thermal stratification of reservoirs to obtain cold water for cooling green data centers (GDCs) is a new mode of energy conservation and emission reduction. However, global warming is expected to alter this phenomenon in deep reservoirs and thus may affect the digitalization process. While the frequency and intensity of extreme climate (EC) events are increasing under a changing climate, the impacts of these highly destructive events on thermal stratification and the related cascading effects on GDC cold-water supplies are still unclear. A two-lateral-dimensional thermohydrodynamic model was established to determine the characteristics of reservoir thermal stratification changes and its potential water environment impacts based on the heat extreme experienced by the Jinshuitan Reservoir, a large, pumped storage power station (PSPS) with a GDC in southeastern China. Fourteen different PSPS inlet/outlet schemes under 2 climate scenarios were designed, and two new indexes, namely, the risk index of cold-water shortage and the index of thermal stratification, were proposed to explore the impact of extreme climates on GDC water extraction. The results showed that compared to the present climate conditions, the reservoir experienced stronger thermal stratification with a 20.6 % average increase in thermal stability, a longer thermal stratification duration with a transitional trend from seasonal to permanent stratification, and a thinner cold-water layer with a 15-m average decrease. Changes in the thermal stratification of reservoirs under EC conditions will benefit some species, such as diatoms (except for early July and the period from mid-August to early October), green algae and cyanobacteria and the migration of warm-water fish, but adversely impact dissolved oxygen, diatoms and cold-water fish. Furthermore, the risk of cold-water shortages under EC conditions was consistently greater than that under average climate (AC) conditions (traditional assessment) when the elevation of pumped storage intake/outlet was less than 145 m. According to the traditional assessment method, the intake/outlet elevation of pumped storage reservoirs resulted in a 60.27 % increase in the risk of cold-water shortages during climate extremes. Furthermore, the demand for green cold-water withdrawal and optimal pumped storage power generation benefits were met when the PSPS intake/outlet elevation was 145 m. Beyond solving this specific case, this study elucidates the importance of linking the thermal stratification and data center of cold-water withdrawal to ECs. These findings provide new insights for increasing climate change resilience. [Display omitted] [ABSTRACT FROM AUTHOR]

The impacts of large-scale coastal structures on tidal dynamics have been studied extensively over the past decades, but the relevant mechanisms are not fully understood. In this study, a two-dimensional Delft3D barotropic tidal model is applied to investigate the tidal dynamic changes induced by the large-scale sequential constructions of Huanghua-Binzhou Harbor in the northeastern China during year 2003–2016. It was found that the predominant M 2 tide is increased on the stoss side and decreased on the lee side of the harbor by 2–6 cm due to the harbor constructions. This feature is due to 1) the increased and decreased potential tidal energy on the stoss and lee side, respectively, by the harbor structures; 2) the structure-induced changes in momentum flux is balanced by pressure gradient, and thus leads to a larger tidal range on the stoss side and a smaller tidal range on the lee side. The sensitivity studies on nonlinear M 4 tide demonstrate that it is generated locally by M 2 self-self interaction, which is not only related to M 2 tidal energy but also nonlinearity. Consequently, M 4 tide increases towards the shore on the tidal flat with natural slope due to enhanced nonlinearity by decreasing water depth, but is proportional to M 2 tide on the tidal flat with a constant water depth, where local nonlinearity is nearly the same in space. In addition, the energy transfer from M 2 to M 4 is affected by the structure-induced changes in nonlinearity, resulting in different responses of M 2 and M 4 tide to the coastal structure. • Numerically investigate the tidal dynamics changes induced by the large-scale sequential constructions. • Predominant M 2 tide increased on the stoss side and decreased on the lee side of the harbor jetties. • Structure-induced changes in current acceleration is balanced by the changes in pressure gradient. • M 4 tide is generated locally by M 2 self-self interaction, which is relative to M 2 tidal energy and local nonlinearity. • Three prominent separated bands of tidal energy density appear in the third harbor construction phase. [ABSTRACT FROM AUTHOR]

Silty coast, as a transitional state between muddy coast and sandy coast, possesses a considerable percentage of the overall coast in China. Huanghua-Binzhou coast in the southwest Bohai Bay in the northeastern China is a typical silty coast which is vulnerable to cold fronts when its seabed is prone to suffer suddenly drastic erosion and deposition due to the sediment there with relatively low incipient velocity and high settling velocity. In this study, a multi-sediment fraction model was established and two-way coupled with the wave-tide-surge model to investigate the responses of the sediment transport and morphodynamics of Huanghua-Binzhou coast to a cold front event during 10–13th Oct. 2003. The model results demonstrate that three sediment fractions, i.e. mud, silt and sand, showed different responses to the storm due to their different spatial percentages and distinct physical properties. The silt fraction, as the primary fraction, played a leading role in the suspension and transport of the total sediment, and showed a pattern of "deposition-erosion-deposition" in the cross-shore direction like the total morphological change. The fine sediment was transported westward and offshore during the storm, which indicated the sediment coarsening in the study area. The depth-induced wave modulation considerably enhanced the resuspension ability of the nearshore waves for sediment and thus played a critical role in intensifying the erosion. The Huanghua waterway siltation mainly resulted from the resuspension of the offshore sediment by the strong wind waves and its westward transport by the wind-induced currents during the storm. The construction of two long jetties in 2006 can significantly reduce the deposition in the waterway by 75%, and the additional large-scale construction in 2016 can further lessen the waterway siltation by intercepting the westward sediment transport and reduce the suspended sediment concentration by 30% by the land reclamation in the study area. • Silt played a leading role in sediment transport and morphological evolution during the cold front event. • Depth-induced wave modulation considerably enhanced nearshore sediment resuspension. • Offshore sediment resuspension and westward transport by strong wind-induced waves and currents caused waterway siltation. • The extended jetties in 2006 reduce deposition in the waterway by 75% under the action of the cold front event in 2003. [ABSTRACT FROM AUTHOR]

• Temporal MPs in Anthropocene strata does not increase linearly with time. • MP stratigraphy mirrors a history of plastic production and use. • MPs reflect policy interventions with industrialization and waste management. • Provenances, properties, and sedimentation environment influenced MP stratigraphy. • MPs provide a unique marker for the beginning of the Anthropocene Epoch. Microplastics (MPs) are considered one of the significant stratigraphic markers of the onset of the Anthropocene Epoch; however, the interconnections between historic plastic production, waste management as well as social-economic and timing of MP accumulation are not well understood. Here, stratigraphic data of MPs from a sediment core from Xiamen Bay, China, was used to reconstruct the history of plastic pollution. Generalized Additive Modeling indicates a complex temporal evolution of MP accumulation. The oldest MPs deposited in 1952 was 30,332 ± 31,457 items/kg•dw, coincide with the infancy of the plastic industry and onset of the Anthropocene. The Cultural Revolution (1966 – 1976) curtailed these initial increases. Subsequent rapid growth in MPs during the late 1970s was peaked at 189,241 ± 29,495 items/kg•dw in 1988 and was followed by a drastic decline in the late 1980s to a low value in 1996 (16,626 ± 26,371 items/kg•dw), coinciding with proliferation of MP sources, coupled with evolution of plastic production, consumption, and regulation. Increasing MPs over the past decades implies that previous mitigation measures have been compromised by the escalated influx of MPs from increasing plastics production, legacy MPs remaining in circulation and insufficient waste management for a growing population. The present methodology and results represent a conceptual advance in understanding how changes in policy and economics over time correlate to changes in MP records in Anthropocene strata, which may help make decisions on plastic pollution mitigation strategies worldwide. [Display omitted] [ABSTRACT FROM AUTHOR]

The southwestern part of Bohai Bay in northeastern China is a shallow-water coast with a long fetch for water to pile up to produce large storm surge under strong wind action during the extreme weather condition. In addition, the coastline along the bay has experienced significant environmental impacts from large scale harbor constructions in the past two decades. Consequently, there is a pressing need to better understand the effects of two local large scale sequential harbor constructions on storm surge and coastal vulnerability in the bay area. The extreme cold front weather on 10-13th October 2003 caused a 1.31 billion Yuan damage. A two-way coupled tide-surge-wave Delft3D model is used to investigate the impact of the harbor constructions from 2003 to 2016 on the interaction of tide, storm surge and wave during a storm like that. The wind field by the newly-released global reanalysis wind product ERA5 of European Centre for Medium-Range Weather Forecasts (ECMWF) has been improved by assimilation with field observations at a higher resolution than previous version and is used to drive the tide, surge and wave modelling framework. The model results indicate that the storm surge in the study area is dominated by the wind-induced surge before and after the constructions whereas the maximum contribution from wave-induced surge (wave setup) is increased from 5%-15% to 8%–20% by the harbor constructions between 2003 and 2016. It is found that semi-diurnal modulation of storm surge is generated by nonlinear tide-surge interaction, which is mainly attributed to local tidal acceleration in the offshore zone and bottom stress in the nearshore zone respectively. The harbor constructions affect the coastal storm surge mainly through nonlinear tide-surge-wave interaction. In addition, the quarter-diurnal variation of storm surge induced by the harbor constructions is due to the influences of the harbor constructions on the local quarter-diurnal tidal constituents and their modulation of wave momentum transfer to coastal circulation. • Newly-released ERA5 wind is modified by observation using linear regression. • Semidiurnal surge is evident in mildly-sloping SW Bohai Bay in a cold front event. • Tide-surge interaction in offshore (nearshore) is due to acceleration (bottom friction). • Wave-induced surge contributes 5%–15% (8%–20%) to storm surge in layout 2003 (2016). • Surge change due to harbor relates with nonlinear tide-surge and wave interactions. [ABSTRACT FROM AUTHOR]