浙江省出入太湖河道水量水质及污染物通量变化(2007-2019年)     

何锡君  孙英军  王贝  姚岳来  陈革强  吴珍梅  王冬 《湖泊科学》2021,33(5):1425-1435

自2007年太湖无锡水危机事件后,太湖流域内各项水污染防治工作进入快车道,近年来浙江省持续开展水环境治理,针对不同污染源进行分类施策、精准治理,整体水环境质量得到了显著改善.本文根据2007-2019年浙江省环太湖水文巡测资料及主要出入太湖河道水质监测成果,全面分析了出入湖河道的水量、水质及污染物通量的时空变化趋势.结果表明,2007-2019年浙江省年均入湖水量为27.39亿m³,年均出湖水量为26.42亿m³,环湖河道进出水量在2007-2014年以出湖为主,2015-2019年以入湖为主,2015-2019年入湖水量增加受该时段地区降水量较丰的影响.2007-2019年浙江省环湖河道COD_Mn、NH₃-N和TP浓度呈明显下降趋势,TN浓度有所下降,除TN仍处于Ⅴ~劣Ⅴ类水外,其余指标已处于Ⅱ~Ⅲ类水标准,当前环湖河道的COD_Mn和NH₃-N指标已达到《太湖流域水环境综合治理总体方案（2013年修编）》提出的目标值,但TN和TP浓度仍存在较大差距.浙江省环湖河道年平均COD_Mn、NH₃-N、TP和TN入湖通量分别为1.12万、0.18万、0.03万和0.90万t,出湖通量分别为1.13万、0.10万、0.03万和0.62万t,环湖河道除COD_Mn以净出湖通量为主外,其余指标均以净入湖通量为主,存在一定入湖滞留,其中水量是影响入湖通量的关键因子.  相似文献   

山西地震带北段与张家口——渤海地震带不同深度CO_2和Rn气体通量的差异性     

赵红坤  王万丽  周晓成  石宏宇  孙玉涛  刘永梅 《地震地磁观测与研究》2020,41(2):113-122

2014年在山西地震带北段和张家口—渤海地震带布设35个测量剖面,测量土壤气CO_2、Rn浓度及深度20 cm、1 m的CO_2和Rn通量。测量结果表明:(1) CO_2、Rn浓度与深度20 cm、1 m的CO_2、Rn通量的平均值和最大值变化趋势大致相同,均呈自西向东的增大趋势;(2)深度20 cm、1 m的CO_2和Rn通量相关性均不明显,但1 m深的CO_2、Rn通量明显较高;(3) CO_2和Rn浓度、通量变化主要与区域复杂的地震活动性和断层活动性有关,主要受到地表化学成分和区域岩石地球化学影响。  相似文献   

罗源湾海岸盐沼悬沙粒度及沉降速率的观测和分析   总被引：1，自引：1，他引：0       下载免费PDF全文

王爱军  叶翔  陈坚 《海洋学报》2009,31(2):165-174

海岸盐沼对环境变化的响应非常敏感,是研究全球变化和人类活动对海岸带环境影响的典型区域之一。影响盐沼演化过程的一个非常重要的因素就是水体悬沙特性[1]。在沿岸水域环境中,有机和无机的细颗粒悬沙在物理和化学的作用下絮凝成大颗粒的絮凝体,其粒径和沉降速率通常是分散细颗粒悬沙的好几倍,因此絮凝过程基本上改变了细颗粒悬沙的水动力行为过程[2]。絮凝体因相对分散颗粒物有较高的沉降速率,水中的悬沙更容易沉降到滩面,控制着水体中的细颗粒物质的沉降通量[3]。  相似文献   

海洋沉积物中汞的释放通量及热力学研究     

单长青  吴俊文  刘汝海 《海洋通报》2009,28(4)

以胶州湾海泊河口和李村河口为对象,研究了其沉积物中的汞向海水的释放.结果表明,在静态条件下,沉积物汞向海水释放,平衡时海泊河口和李村河口沉积物汞的释放量分别为 0.070 5 ～ 0.117 μg/g 和 0.056 5 ～ 0.093 5 μg/g;汞的释放通量在前 2 h 最大,随后逐渐减小,通量与温度呈指数正相关.通过对汞释放的热力学分析,汞释放的反应热大于零,分别为 9.92 kJ·mol-1 和 9.98 kJ·mol-1,说明汞的释放是一个吸热过程;汞的释放是一个熵增过程;两个实验反应的标准自由能变分别为 2.34 ～ 3.22 kJ·mol-1和 1.19 ～ 2.20 kJ·mol-1,而且温度越高,ΔG0 越小,越利于反应向正方向进行.  相似文献   

Accelerated sediment delivery to continental margins during post-orogenic rebound of mountain ranges     

Thomas Bernard  Hugh D. Sinclair 《Basin Research》2023,35(2):642-661

Changes in sediment flux to continental margins are commonly interpreted in terms of tectonic growth of topography or climatic change. Here, we show that variations in sediment yield from orogenic systems, previously considered as resulting from climate change, drainage reorganisation or mantle processes can be explained by intrinsic mechanisms of mountain belt/foreland basin systems naturally evolving during post-orogenic decay. Numerical modelling indicates an increase of sediment flux leaving the orogenic system synchronous with the cessation of deposition in the foreland basin and the transition from late syn- to post-orogenesis. Experiments highlight the importance of lithospheric flexure that causes the post-orogenic isostatic rebound of the foreland basin. Erosion of the rebounding foreland basin combined with continued sediment flux from the thrust wedge drives an acceleration in sediment outflux towards continental margins. Sediment budget records in natural settings such as the Northern Pyrenees or Western European Alps also indicate accelerated post-orogenic sediment delivery to the Bay of Biscay and Rhône Delta respectively. These intrinsic processes that determine sediment yield to continental margins must be accounted for prior to consideration of additional external tectonic or climatic controls.  相似文献   

长江口北槽黏性细颗粒泥沙特性的试验研究   总被引：2，自引：0，他引：2  

杨扬  庞重光  金鹰  周晶晶 《海洋科学》2010,34(1):12-24

选用长江口北槽黏性细颗粒泥沙,在不同盐度的人工海水中通过静水沉降、动水沉降等各种试验手段了解其基本特性。在静水沉降管中观测了胶粒的电化学絮凝过程和重力碰并过程,于不同盐度条件下找出最佳絮凝盐度;并通过黏性细颗粒泥沙在流动海水中絮凝的试验研究,揭示其在动水中絮凝的机理和规律,及不同条件下的起动流速、不淤流速、沉降速度等特征值,从而分析其落淤情况。研究结果表明,长江口北槽细颗粒黏性泥沙的最佳絮凝盐度约为15,起动流速为15~20 cm/s,这与泥沙的淤积固结时间有关,而不淤流速约为60 cm/s。并由试验得到了挟沙力与流速之间的经验关系,以及用于估算不同流速条件下泥沙沉降速度及淤积量的经验公式。这些结果可用于长江口航道的疏浚、整治工作中,具有一定的理论指导意义。  相似文献   

Analysis of growing season carbon and water fluxes of a subalpine wetland in the Canadian Rocky Mountains: Implications of shade on ecosystem water use efficiency     

Dylan M. Hrach  Richard M. Petrone  Adam Green  Myroslava Khomik 《水文研究》2022,36(1):e14425

Mountain regions are an important regulator in the global water cycle through their disproportionate water contribution. Often referred to as the “Water Towers of the World”, mountains contribute 40%–60% of the world's annual surface flow. Shade is a common feature in mountains, where complex terrain cycles land surfaces in and out of shadows over daily and seasonal scales, which can impact water use. This study investigated the turbulent water and carbon dioxide (CO₂) fluxes during the snow-free period in a subalpine wetland in the Canadian Rocky Mountains, from 7 June to 10 September 2018. Shading had a significant and substantial effect on water and CO₂ fluxes at our site. When considering data from the entire study period, each hourly increase of shade per day reduced evapotranspiration (ET) and gross primary production (GPP) by 0.42 mm and 0.77 g C m^?2, equivalent to 17% and 15% per day, respectively. However, the variability in shading changed throughout the study, it was stable to start and increased towards the end. Only during the peak growing season, the site experienced days with both stable and increasing shade. During this time, we found that shade, caused by the local complex terrain, reduced ET and potentially increased GPP, likely due to enhanced diffuse radiation. The overall result was greater water use efficiency during periods of increased shading in the peak growing season. These findings suggest that shaded subalpine wetlands can store large volumes of water for late season runoff and are productive through short growing seasons.  相似文献   

西太平洋暖池区的海气通量及整体交换系数   总被引：3，自引：1，他引：2  

徐静琦  魏皓  顾海涛  武建平 《气象学报》1997,55(6):703-713

根据西太平洋海域弱风、高温、潮湿的大气状态特征,提出了在光滑面存在粘性副层气流中的廓线的层结订正方案。用此模式对西太平洋暖池区ＴＯＧＡＣＯＡＲＥＩＯＰ期间,在向阳红５号船（２°Ｓ,１５４°Ｅ）获取的海面风、温、湿梯度资料进行了处理。计算结果显示西太平洋暖池区贴水层气流中不稳定层结占５０％－８０％,其中很不稳定的占１０．３％;该海区海气通量和整体交换系数受层结影响远大于受风速的影响;海气通量和整体交换系数随不稳定程度增加而增大,在相同风速下量值可相差４倍以上;其变化范围为０．３×１０－３—３．２×１０－３。由此可见,层结的影响使它们的变化大于其它海区的结果。在ｕ１０＝０－１０ｍ／ｓ范围内,中性化整体交换系数平均为ＣＤＮ＝１．２×１０－３,ＣＨＮ＝１．１４×１０－３,ＣＥＮ＝１．１９×１０－３,与Ｌａｒｇｅ和Ｐｏｎｄ（１９８１,１９８２）不稳定条件的研究结果相差无几。  相似文献