A Study of the Impact of the Fukushima Nuclear Leak on East China Coastal Regions

ABSTRACT

The nuclear leak in Fukushima, Japan, which occurred on 11 March 2011, had disastrous impacts in many regions of the northern hemisphere. In this study, a highly resolved, one-way nesting model incorporating tides is set up with the Regional Ocean Modeling System (ROMS) to simulate and predict the potential impact of the disaster on the East China Sea (ECS), with the large domain covering the entire North Pacific. Of the four main waterways, namely Taiwan Strait, the waterway east of Taiwan, Tokara Strait, and Tsushima Strait, the first two have net fluxes of radionuclides into the ECS, while the other two have net outward transport during the entire 14-year period of the simulation (2011–2025). Differing from previous studies, we have taken into account background radionuclides in this model; the results agree well with available observations. Based on the simulation, the radioactive material has arrived in the ECS. The amount will reach its peak in 2019 and late in 2021 will return to its original state before the accident. Temporally it has a clear seasonal variability, with peaks usually appearing during winter. Spatially it is not homogeneously distributed, and the concentration has local maxima along the coasts of Jiangsu and Zhejiang, which are the most populous regions of China; a conspicuous feature is the Subei Bank high in summer. This study is expected to help form policy for rapid response to such disasters.     

阳宗海砷污染背景下浮游植物的时空分布特征及其驱动因子解析

人类活动导致的重金属污染是湖泊水体面临的主要环境压力之一.云南高原湖泊阳宗海于2008年暴发了砷污染事件且水体砷浓度目前仍然超过生活饮用水卫生标准,严重影响了水安全和生态系统健康.本研究于2015年4月-2016年2月每两月对阳宗海南、中、北部湖区进行采样调查及分析,共鉴定出浮游植物7门44属68种,绿藻门种数最多.蓝藻门占绝对优势,其中伪鱼腥藻（Pseudoanabaena sp.）、浮丝藻（Planktothrix sp.）、束丝藻（Aphanizomenon sp.）为全年的优势种,这与已有调查显示的阳宗海砷污染后浮游植物群落中蓝藻占优的基本特征一致.方差分析结果表明浮游植物生物量在时间尺度上呈现显著的变化特征,最大值出现在8月（14.06 mg/L）,最小值出现在12月（1.23 mg/L）,而空间差异不显著.Pearson相关分析显示,浮游植物总生物量与水温、pH呈显著正相关.而与砷、透明度、锰、钠、钾和总磷浓度呈显著负相关,冗余分析结果表明,水温、砷、钙、锰、钾共同解释了阳宗海浮游植物群落结构变化的57.18%.方差分解的结果进一步表明,水温、钙离子和砷三者作用共同解释了浮游植物群落结构变化的32.05%,其中水温和钙离子分别独立解释了群落变化的12.45%和8.28%,水体砷浓度仅独立解释了2.33%,但与水温共同作用解释了9.46%.因此,我们推测水温的季节性波动导致了湖泊水体热力分层的明显变化,其中水体混合作用的增强可能会促进底泥释放过程并增加表层水体的砷浓度,进而影响了浮游植物群落的季节性变化.研究结果有利于评价重金属污染对湖泊的长期生态效应,并为砷污染湖泊的环境修复提供重要的科学依据.     

渤黄东海40年温盐流模拟与初步分析

使用ROMS(regional oceanic modeling system)模式模拟了40年的渤黄东海温盐流,数据包括三维的温度、盐度、流速、流向和海表高度,同时包含了逐小时的潮汐信息。将模拟结果与观测资料和卫星反演数据进行对比,检验了模式准确性。整体上,模式模拟的水位与近岸观测值基本一致,能够准确再现风产生的增水;模式较为准确的再现了渤黄东海的温度分布,在深水区模拟的温盐剖面与观测值基本一致;模式模拟渤黄东海区域的海表高度和海表流与卫星反演结果相比偏小,但分布趋势相近。模式结果可以为研究气候变化对水位的影响和黄海暖舌的扩散过程等现象提供数据支持。     

On evaluating the effect of assimilating glider-observed T/S profiles with different horizontal resolutions and assimilation frequencies

Ocean Dynamics - Underwater gliders can provide real-time and spatially flexible temperature/salinity (T/S) observations for improving the marine forecast by data assimilation. By conducting...     

An Effective Reservoir Parameter for Seismic Characterization of Organic Shale Reservoir

Sweet spots identification for unconventional shale reservoirs involves detection of organic-rich zones with abundant porosity. However, commonly used elastic attributes, such as P- and S-impedances, often show poor correlations with porosity and organic matter content separately and thus make the seismic characterization of sweet spots challenging. Based on an extensive analysis of worldwide laboratory database of core measurements, we find that P- and S-impedances exhibit much improved linear correlations with the sum of volume fraction of organic matter and porosity than the single parameter of organic matter volume fraction or porosity. Importantly, from the geological perspective, porosity in conjunction with organic matter content is also directly indicative of the total hydrocarbon content of shale resources plays. Consequently, we propose an effective reservoir parameter (ERP), the sum of volume fraction of organic matter and porosity, to bridge the gap between hydrocarbon accumulation and seismic measurements in organic shale reservoirs. ERP acts as the first-order factor in controlling the elastic properties as well as characterizing the hydrocarbon storage capacity of organic shale reservoirs. We also use rock physics modeling to demonstrate why there exists an improved linear correlation between elastic impedances and ERP. A case study in a shale gas reservoir illustrates that seismic-derived ERP can be effectively used to characterize the total gas content in place, which is also confirmed by the production well.     

基于局地多尺度能量涡度分析法(MS-EVA)的北半球夏季西太平洋MJO动能分析

采用局地多尺度能量涡度分析法(MS-EVA)和基于MS-EVA的局地正则传输与不稳定性理论对北半球夏季MJO的动能变化进行了诊断分析。结果表明:1)引起对流层上层和下层MJO动能变化的主要影响因素是有效位能转换和气压梯度力做功,其中有效位能转换在对流中心以北有明显的正的大值带,是MJO的主要动能源;气压梯度力做功则主要是将从有效位能转换而来的动能在空间重新分布。2)引起对流层中下层MJO动能变化的主要因素是动能跨尺度传输作用,其中大尺度向MJO尺度的跨尺度传输在对流中心附近表现为明显的正值,因此是该高度上MJO的动能源,并受5~15°N区域上空正压不稳定制约。3)MJO与天气尺度系统间的动能传输则主要表现为MJO的动能汇,其与MJO环流场分布以及MJO对天气尺度波动动量通量的平流输送有关。     

南海温盐流数值产品构建及评估

基于区域海洋模式ROMS构造了一套覆盖中国南海的40年（1980—2019年）温盐流数值产品OCEAN＿SCS。OCEAN＿SCS的变量包含了温度、盐度、流速、流向以及海表高度。OCEAN＿SCS的水平空间分辨率为0.1°×0.1°,垂向分层40层（0～5 000 m）,时间分辨率为1小时,包含潮汐信息。利用独立的观测资料对OCEAN＿SCS进行了初步评估,评估对象包括温度、盐度、海表高度、海流、潮位和增水。在不包含资料同化的前提下,OCEAN＿SCS的模拟精度达到了较高的水准。OCENA＿SCS的构建将为南海海洋环境的研究提供数据支撑,并服务于南海海洋环境保障。