西双版纳地区近45年来气候变化特征

根据云南省西双版纳州景洪市气象站1961年1月至2005年1月的气温及降水资料,分析了西双版纳近45年来的气候变化特征,得出近45年来两双版纳年降水量呈下降趋势(-20.72 mm/10a),夏季降水量减少较明显(-24.28 mm/lOa),春季降水量却呈上升趋势(11.18mm/10a);年平均气温呈上升趋势(0.262℃/10a),四季气温也呈上升趋势,尤其是冬季变暖最明显(0.483℃/10a);年极端低温的上升趋势(0.545℃/10a)远远大于年极端高温的下降趋势(-0.088℃/10a).以20世纪70年代末为界将近45年西双版纳气候分为冷、暖两个阶段,前为冷期,后为暖期.     

喀什及其周围地区农村房屋建筑易损性矩阵的建立

在搜集喀什及其周围地区农村房屋震害资料的基础上,建立了农村分类房屋的地震易损性矩阵,将其与国内相研究结果进行了对比,认为结果的差异主要与研究区农村房屋质量和场地土条件有关,今后工作中应对城镇房屋建筑的易损性矩阵进行及时总结和研究。     

KZWY91—1000型钻孔瓦斯压力测定仪的应用

通过对山西省云台山5次瓦斯测压试验,系统介绍了钻孔瓦斯压力测定仪的结构、工作原理和测试程序。并从测压泥浆质量管理、提高封孔效果和把握卸压环节总结出一整套测试经验。分析了测试原理、各主要部件性能、成功率高低、经济效益等。      

不同出露时间下洞庭湖洲滩土壤及生态系统呼吸特征

于2015年1月洞庭湖枯水期,针对不同出露时间下的洲滩,调查其土壤理化性质,并利用LI-8100便携式二氧化碳气体分析仪监测其生态系统呼吸.结果表明：在洞庭湖枯水期,洲滩出露后,洲滩土壤有机质、硝态氮、铵态氮和全氮含量随出露时间增长而先升高后降低.土壤溶解性有机碳含量是影响洞庭湖枯水期洲滩生态系统呼吸强度的最重要影响因子.溶解性有机碳含量随出露时间增长而提高,洲滩生态系统呼吸强度随之提高,并在洲滩出露约60天后达到最高值.出露洲滩生态系统呼吸通量均值为0.72±0.55 μmol/（m²·s）,超过杨树林地、芦苇地和农田地,成为洞庭湖区冬季CO₂排放最活跃的区域.     

基于VIIRS数据的中国东部气溶胶光学厚度反演算法改进

VIIRS(Visible Infrared Imaging Radiometer Suite)作为MODIS(The MODerate resolution Imaging Spectroradiometer)的后继传感器,可在全球范围内实现对气溶胶的连续时空监测.卫星反演的气溶胶光学厚度(Aerosol Optical Depth,AOD)是研究地球能量收支平衡、气候效应和空气质量的重要大气参数.但在中国重污染天气情况下,现有的VIIRS陆地气溶胶产品存在一定不足.因此,本研究改进云识别方法,优化像元筛选,约束气溶胶类型选择,实现重污染情况下AOD的反演.基于地基AERONET(AErosol RObotic NETwork)的验证结果表明,相比NOAA(National Oceanic and Atmospheric Administration)产品,改进后的反演结果克服了反演值偏低的问题,且表现出更好的相关性,RMSE从0.236下降到0.219.为验证在重污染条件下改进算法的适用性和准确性,本文对比了两种污染条件下的反演结果(0.61).统计结果表明,在较重污染天气条件下(AODAERONET>1),相比NOAA的AOD产品,本文结果的反演率从32.3%提升为68.8%,回归分析的斜率提高为0.80,相关系数达到0.76,均方根误差为0.307,在增加反演量的同时保证了反演的精度.     

徐州地震台2016年11月—2017年YRY-4分量钻孔应变仪异常核实

2016年11月-2017年,徐州地震台YRY-4分量钻孔应变曲线出现"漏斗"状向下凹陷的压性变化,从场地环境、观测环境、观测系统进行现场核实,并对异常期间的观测数据进行对比分析,排除外界干扰及仪器自身问题,认为此次数据畸变可能反映了地下应力的真实变化,应为地下地质构造发生变化所致。     

The effects of the thermal state of overriding continental plate on subduction dynamics: Two-dimensional thermal-mechanical modeling

The dynamic process of ocean-continent subduction depends on not only the properties of the subducting oceanic plate, but also the characteristics and state of the overriding continental plate. Numerical models conducted to date have mostly focused on the oceanic lithosphere in this regard; research on the properties of overriding continental lithosphere remains relatively limited, especially the influence of its thermal state on subduction dynamics. Here we explored the performance of continental lithosphere with different thermal states during the subduction process using two-dimensional thermal-mechanical modeling and systematically investigated the effects of the thermal state of overriding continental plate, the age of subducting oceanic plate, and relative convergence rate on subduction dynamics. Modeling results show that:(1) When the geothermal gradient of continental crust is low(between 10 and 15 ℃ km~(-1)), the oceanic plate first subducts at a low angle. As subduction continues, the slab dip gradually increases and the slab begins to retreat rapidly driven by its negative buoyancy, opening an ocean basin ranging from 600 to 1100 km in width. This leads to the decoupling between the overriding continental plate and oceanic plate. As the trench retreat continues, the horizontal deviatoric stress inside the overriding continental crust alternates between being positive and negative in a local area. Thinning of the overriding lithosphere mainly occurs at the region adjacent to the subduction zone, where the surface experiences significant subsidence.(2) When the geothermal gradient of continental crust is higher(greater than 15 ℃ km~(-1)), oceanic plate retreat causes the overriding continental plate to be strongly stretched. In this case, the trench retreat distance decreases and the width of the ocean basin also reduces by between 100 and 1000 km. The horizontal deviatoric stress inside the whole overriding continental crust first manifests as compression and then changes into extension, which causes the surface to first uplift and then slowly subside.(3) Increasing the age of oceanic lithosphere accelerates trench retreat and promotes overriding plate thinning.(4) An advancing overriding continental plate slows down trench retreat. In cases where the geothermal gradient of continental crust is greater than 17.5 ℃ km~(-1), the hot continental crust experiences gravitational collapse and is overthrusted onto oceanic lithosphere, resulting in slow trench retreat. We analyzed the subduction process of the western Paleo-Pacific Plate in the Early Cretaceous based on our modeling results and discussed its possible control on the tectonic evolution of the rift basins in east Asia. We suggest that the development of a wide rift basin system on the Amurian Superterrane in the Early Cretaceous was likely related to slow trench retreat and the collapse of the hot crust, and the formation of a series of passive rift basins in the North China Craton was likely caused by the relatively cold thermal state of the lithosphere and the rapid retreat of the Paleo-Pacific Plate.     

Embodied carbon emissions in China-US trade

China-US trade holds great significance for the world's political and economic landscape. Since 2018, the US government has imposed additional tariffs on Chinese exports on the grounds of the US trade deficit with China. However, the transfer of pollutants embodied in trade and the differences in environmental costs between China and the US have not been widely recognized. In this study, we quantify the embodied carbon emissions(the "virtual" emissions associated with trade and consumption) in China-US trade by constructing a carbon dioxide emissions inventory and a multiregional input-output model.The study shows that the US benefits from a trade surplus of environmental costs by importing energy-intensive and pollutionintensive products from China, which increases China's environmental pollution and abatement costs. In 2017, 288 Mt CO_2 emissions were associated with products produced in China but finally consumed in the US, and only 46 Mt CO_2 were associated with the US products that were consumed in China. From this perspective, China-US trade results in a net transfer of 242 Mt CO_2 per year from the US to China, accounting for approximately 5% of the total CO_2 emissions in the US. More importantly, for Chinese products exported to the US, the carbon emissions embodied in one unit of economic value amount to 0.92 kg/$(RMB:USD=6.8:1), but for US products exported to China, the carbon emissions embodied in one unit of economic value amount to 0.53 kg/$, which means China will incur environmental costs that are 74% higher than those of the US while enjoying the same economic benefits. This environmental trade deficit has burdened China with higher environmental costs than economic benefits.To address this environmental trade deficit, China should actively promote further industrial upgrading and energy structure adjustment and increase investment in innovation and RD, thereby increasing the value added per unit of export products and reducing the environmental cost of producing export products.     

甲醛溶液对发头裸腹溞及其体表聚缩虫影响的试验

不同浓度的甲醛溶液对枝角类发头裸腹溲Ｍｏｄｉｎａｉｒｒａｓａ的致毒效应以及对其体表附着的聚缩虫Ｚｏｏｔｈａｍｉｕｍｓｐ．的杀灭效果的试验结果表明,１２ｈ、２４ｈ两俱和用时段中,甲醛浓度与发头裸腹溲相对存活率之间以及甲醛浓度与发头裸腹溲体表聚缩虫营养体脱落率之间存在一定的函数关系。