Carbon pools and fluxes in the China Seas and adjacent oceans

The China Seas include the South China Sea, East China Sea, Yellow Sea, and Bohai Sea. Located off the Northwestern Pacific margin, covering 4700000 km~2 from tropical to northern temperate zones, and including a variety of continental margins/basins and depths, the China Seas provide typical cases for carbon budget studies. The South China Sea being a deep basin and part of the Western Pacific Warm Pool is characterized by oceanic features; the East China Sea with a wide continental shelf, enormous terrestrial discharges and open margins to the West Pacific, is featured by strong cross-shelf materials transport; the Yellow Sea is featured by the confluence of cold and warm waters; and the Bohai Sea is a shallow semiclosed gulf with strong impacts of human activities. Three large rivers, the Yangtze River, Yellow River, and Pearl River, flow into the East China Sea, the Bohai Sea, and the South China Sea, respectively. The Kuroshio Current at the outer margin of the Chinese continental shelf is one of the two major western boundary currents of the world oceans and its strength and position directly affect the regional climate of China. These characteristics make the China Seas a typical case of marginal seas to study carbon storage and fluxes. This paper systematically analyzes the literature data on the carbon pools and fluxes of the Bohai Sea,Yellow Sea, East China Sea, and South China Sea, including different interfaces(land-sea, sea-air, sediment-water, and marginal sea-open ocean) and different ecosystems(mangroves, wetland, seagrass beds, macroalgae mariculture, coral reefs, euphotic zones, and water column). Among the four seas, the Bohai Sea and South China Sea are acting as CO_2 sources, releasing about0.22 and 13.86–33.60 Tg C yr~(-1) into the atmosphere, respectively, whereas the Yellow Sea and East China Sea are acting as carbon sinks, absorbing about 1.15 and 6.92–23.30 Tg C yr~(-1) of atmospheric CO_2, respectively. Overall, if only the CO_2 exchange at the sea-air interface is considered, the Chinese marginal seas appear to be a source of atmospheric CO_2, with a net release of 6.01–9.33 Tg C yr~(-1), mainly from the inputs of rivers and adjacent oceans. The riverine dissolved inorganic carbon (DIC) input into the Bohai Sea and Yellow Sea, East China Sea, and South China Sea are 5.04, 14.60, and 40.14 Tg C yr~(-1),respectively. The DIC input from adjacent oceans is as high as 144.81 Tg C yr~(-1), significantly exceeding the carbon released from the seas to the atmosphere. In terms of output, the depositional fluxes of organic carbon in the Bohai Sea, Yellow Sea, East China Sea, and South China Sea are 2.00, 3.60, 7.40, and 5.92 Tg C yr~(-1), respectively. The fluxes of organic carbon from the East China Sea and South China Sea to the adjacent oceans are 15.25–36.70 and 43.93 Tg C yr~(-1), respectively. The annual carbon storage of mangroves, wetlands, and seagrass in Chinese coastal waters is 0.36–1.75 Tg C yr~(-1), with a dissolved organic carbon(DOC) output from seagrass beds of up to 0.59 Tg C yr~(-1). Removable organic carbon flux by Chinese macroalgae mariculture account for 0.68 Tg C yr~(-1) and the associated POC depositional and DOC releasing fluxes are 0.14 and 0.82 Tg C yr~(-1), respectively. Thus, in total, the annual output of organic carbon, which is mainly DOC, in the China Seas is 81.72–104.56 Tg C yr~(-1). The DOC efflux from the East China Sea to the adjacent oceans is 15.00–35.00 Tg C yr~(-1). The DOC efflux from the South China Sea is 31.39 Tg C yr~(-1). Although the marginal China Seas seem to be a source of atmospheric CO_2 based on the CO_2 flux at the sea-air interface, the combined effects of the riverine input in the area, oceanic input, depositional export,and microbial carbon pump(DOC conversion and output) indicate that the China Seas represent an important carbon storage area.     

Geochemical modeling,fate distribution,and risk exposure of potentially toxic metals in the surface sediment of the Shyok suture zone,northern Pakistan

The objective of the current study was to assess the contamination of potentially toxic metals (PTMs) in weathered surface sediment, along stream tributaries, and surrounding area of the river Chitral, Shyok suture zone district Chitral, Pakistan. To understand the geochemical features of 113 sediment, samples were collected from the Mirkhani and Drosh area. Then, different statistical tools including the geo-accumulation index (Igeo), cluster analysis (CA), principal component analysis (PCA), and ecological risk assessment (ERA) were used to unravel the origin, intensity, and exposure level of PTMs to control risk and restore the ecosystem within the study area. The results for the PTMs namely nickle (Ni), chromium (Cr), copper (Cu), cadmium (Cd), lead (Pb), zinc (Zn), and cobalt (Co) in Mirkhani and Drosh were in the following ranges: 10–150, 15–210, 15–250, 0.08–1.00, 10–70, 76–240 and 14–51; and 13–240, 17–210, 15–150, 0.08–0.60, 7–140, 47–150 and 13–36 mg/kg, respectively. In consequence, the potential ecological risk caused by Pb, Ni, Cu, Co, Cr, and Zn is reflected by the percentages of samples with an ecological risk index (ERI) greater than one which were 100%, 91%, 100%, 100%, 92%, and 100%, respectively. However, the overall mean decreasing order of ecological risk of PTMs in the district Chitral was Pb > Ni > Cu > Co > Cr > Zn > Cd. Moreover, the PCA yielded 78% variability which indicated that mineral prospects play an important role in the contamination of sediment. Furthermore, the mineral phases of Pb and Zn suggested supersaturation, while that for Cd revealed unsaturation. The results of Igeo, ERI, and CA indicated contamination of PTMs in the study area. The ERI value of Pb, Ni, Cu, Co, Cr, and Zn was higher than 1 suggesting an ecological risk in the study area. Moreover, the current study showed the dominance of geogenic contamination with major contributions from ultramafic rock and known mineral prospects. Therefore, contaminated sediment of the Shyok suture zone is extremely detrimental to the aquatic ecosystem of the study area.     

哈萨克斯坦地震地下流体监测、预测的现状及其震兆异常特征的分析

40多年来,哈萨克斯坦地震地下流体观测台网历经初期建网、系统清理、政策调整和优化提高4个阶段,目前已形成与中国北京地区流体监测网相当的规模。分析了哈萨克斯坦流体监测台网的地位、台站分布、观测项目、仪器配置及地震分析预测情况。最后,分析了哈萨克斯坦地震地下流体观测资料的特点,并就哈萨克斯坦流体交换资料的震兆异常特征进行了初步总结。     

2000—2017年新疆城镇体系网络结构及规模特征探析

基于城市空间网络结构和规模特征两个方面,运用修正引力模型、社会网络分析、标准差椭圆分析、中心职能模型、泰尔指数模型等,综合刻画2000—2017年新疆城镇体系区域经济的空间发展规律及变化差异。结果表明：（1）从城市空间网络结构来看,新疆城镇体系城市网络的范围持续扩张,等级分层较为突出,空间上表现为以乌昌石城镇群为核心逐级递减的单核圈层结构。联系网络的密度有所下降,但变化较小,各子城镇群的区域联系有待加强。新疆城镇体系的内部凝聚力远大于外向辐射力,整体上形成资源不断涌向核心区域的现象,正处于发展严重不协调阶段。（2）从城市规模特征来看,新疆城镇体系的区域格局主导方向为“东北-西南”,空间结构长期稳定,核心区域集中在天山中部,总体呈现“一级超强,分散组团”的发展格局,乌昌石城镇群与其他区域差距悬殊且极化现象愈加突出,各子区域间表现出明显的等级差异。同时,各地区的差距不断增大,发展也相对割裂,没有形成良好的互动,城镇职能配置不断转移,呈现显著的“虹吸”效应。总体来看,研究区的“中心-外围”特征显著,区域经济格局虽然存在一定弊端,但等级严序的分层结构,次级城镇群间差异较小等特征为优化经济格局框架创造了可能。     

1971—2000年我国东部地区雷暴、冰雹、雷暴大风发生频率的变化

提要：应用1971—2000年华北、华中、华东各省1084个站的地面天气现象观测资料,统计分析了江南（31°N以南）、江淮和黄淮（31°～37°N）及黄河以北（37°N以北）雷暴、冰雹和雷暴大风的年代际变化特征。分析结果表明：雷暴、冰雹、雷暴大风发生频率呈减少趋势。其中江南地区雷暴年代际递减更明显,黄河以北地区冰雹年代际递减最明显,而雷暴大风在三个区域的年代际递减均明显。雷暴大风常与冰雹伴随发生,高原和山地多于平原,高值区位于华北北部和内蒙古中部。对流性天气的减少与水汽和动力条件的减弱有关系。包含热力、动力和水汽条件的综合指数SWEAT无论在空间分布上,还是在30年的演变趋势上,均与对流性天气的分布和演变趋势表现出相似的特征。     

中国地区云对地气系统太阳短波吸收辐射强迫的气候研究

本文利用地球辐射平衡试验（ＥＲＢＥ）和国际卫星云气候计划（ＩＳＣＣＰ）提供的总云量、行星反射率资料,计算并分析了我国年、月平均云对地气系统太阳短波吸收辐射的强迫及其敏感性系数,揭示了它们之间的关系,最后绘制了地气系统短波辐射云强迫的全国分布图。结果表明：我国地气系统短波辐射云强迫及其敏感性系数都与总云量有较好的非线性相关,呈幂指数形式,且季节变化明显。短波辐射云强迫的地理分布与总量配合较好。     

高轨空间碎片的观测模拟

对高轨空间碎片进行了观测模拟。在观测模拟中，分别选取南京和云南两个观测站；采用2种跟踪方式：跟踪恒星和跟踪卫星；对于同一地理经度上的同步卫星进行了观测；提供了发现新目标的方法；并给出了新目标的初轨。这为我国空间碎片的数据库的建立作了有益的尝试，对于卫星和航天器的飞行安全具有特别重要的意义。     

中国地表感热的气候计算及其分布

讨论了我国地表感热的气候计算问题,提出以鲍文比法为基础的感热气候计算式,并据此计算出全国215站月、年平均感热通量密度,进而分析了其在全国的时空分布特点。     

介休市近53年来的温度变化特征及分析

根据介休市气象局1954年-2006年的气温资料,分析了介休市近53年来的温度变化。结果表明：近53年来介休市气温呈上升趋势,上升速度显著高于全国水平,上世纪90年代中期以来这种趋势尤为明显;以20世纪90年代中期为界,近53年来介休市气候分冷、暖两个阶段,前为冷期,后为暖期。     

基于偏正态概率分布的粒度分布次总体分离及其沉积环境指示意义

沉积物颗粒是某种沉积环境和水动力条件下多个沉积过程的最终产物。粒度分布是原始沉积信息的载体,是来自不同沉积过程的多个次总体的叠加,频率曲线可能表现为双峰或者多峰特征。传统的沉积学粒度分析方法并未深入研究次总体;常见的概率分布模型在分离次总体后无法全面计算统计参数。本文以214份鄱阳湖现代沉积物的粒度分布数据为例,利用偏正态概率分布模型共分离提取977个次总体,计算各个次总体的统计参数,并对比分析了不同沉积环境中次总体参数的异同。结果表明：① 次总体均值、方差、偏度、峰度、所占百分比和最大频率等参数规律明显;② 从曲流河河道到河流末端、在河流末端顺流方向上和河道左右两侧远离河道方向上,粒度分布中主要次总体粒度均值逐渐减小,河道间洼地和湖区沉积物粒度分布的各个次总体占比接近;③ 江心洲的河道砂和河漫滩细粒粒度分布分别由3种和5种不同类型次总体组成。该方法可为沉积环境的定量判断和沉积过程的定量研究提供参考。