青岛湾有机质污染带小型底栖生物群落的研究   总被引：7，自引：4，他引：7  

张志南  党宏月  于子山 《中国海洋大学学报(自然科学版)》1993,(1)

本文是1990年6月至10月,对青岛湾东侧有机质污染潮间带的小型底栖动物群落的研究结果。结果指出海洋线虫与多毛类小头虫的数量消长完全一致,它们保持着共栖或互利的共生关系。共鉴定出海洋线虫20种,其中6种占总丰度的90％。依据种类组成计算的Simpsion和Shannon-Wiener多样性指数,以及线虫与桡足类、小头虫与其他多毛类的数量比值指明,该有机质污染带正向着半污染带过渡。  相似文献   

Verification of a VOF-based two-phase flow model for wave breaking and wave–structure interactions     

Phung Dang Hieu  Katsutoshi Tanimoto   《Ocean Engineering》2006,33(11-12):1565-1588

The objective of the present study is to develop a volume of fluid (VOF)-based two-phase flow model and to discuss the applicability of the model to the simulation of wave–structure interactions. First, an overview of the development of VOF-type models for applications in the field of coastal engineering is presented. The numerical VOF-based two-phase flow model has been developed and applied to the simulations of wave interactions with a submerged breakwater as well as of wave breaking on a slope. Numerical results are then compared with laboratory experimental data in order to verify the applicability of the numerical model to the simulations of complex interactions of waves and permeable coastal structures, including the effects of wave breaking. It is concluded that the two-phase flow model with the aid of the advanced VOF technique can provide with acceptably accurate numerical results on the route to practical purposes.  相似文献   

高分辨率时序InSAR在矿区开采沉陷监测中的应用--以霄云矿区为例          下载免费PDF全文

甄洪帅  张红月  姬宗皓  殷幼松 《山东国土资源》2020,36(8):61-67

煤炭资源的高强度开采在促进社会经济发展的同时,也造成了一系列地质环境问题。采煤沉陷区的综合治理及生态修复亟需矿区现状调查数据作为基础支撑,而现状数据的快速更新在监测效率、经济代价及可延续性方面对当前测量方法及工作手段提出了更高的要求。该文以济宁市霄云矿区为例,采用时序InSAR技术对2016—2018年间的15期高分辨率RADARSAT-2XF模式影像开展解译处理,获取霄云矿区的时空形变特征,并结合不同时段开采工作面位置进行了监测结果分析。结果表明,高分辨率时序InSAR技术能够有效识别矿区开采引起的形变迹象,满足采煤沉陷区下沉信息精确获取的监测要求,为大范围开采沉陷信息的获取及影响程度的划定提供了可靠技术方法。  相似文献   

An efficient finite–discrete element method for quasi‐static nonlinear soil–structure interaction problems     

Hoang K. Dang  Mohamed A. Meguid 《国际地质力学数值与分析法杂志》2013,37(2):130-149

An efficient finite–discrete element method applicable for the analysis of quasi‐static nonlinear soil–structure interaction problems involving large deformations in three‐dimensional space was presented in this paper. The present method differs from previous approaches in that the use of very fine mesh and small time steps was not needed to stabilize the calculation. The domain involving the large displacement was modeled using discrete elements, whereas the rest of the domain was modeled using finite elements. Forces acting on the discrete and finite elements were related by introducing interface elements at the boundary of the two domains. To improve the stability of the developed method, we used explicit time integration with different damping schemes applied to each domain to relax the system and to reach stability condition. With appropriate damping schemes, a relatively coarse finite element mesh can be used, resulting in significant savings in the computation time. The proposed algorithm was validated using three different benchmark problems, and the numerical results were compared with existing analytical and numerical solutions. The algorithm performance in solving practical soil–structure interaction problems was also investigated by simulating a large‐scale soft ground tunneling problem involving soil loss near an existing lining. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Hydrological alterations from water infrastructure development in the Mekong floodplains          下载免费PDF全文

Thanh Duc Dang  Thomas A. Cochrane  Mauricio E. Arias  Pham Dang Tri Van  Tonny T. de Vries 《水文研究》2016,30(21):3824-3838

The Mekong floodplains, which encompasses the region from Kratie Township in Central Cambodia to the Vietnamese East Sea, is a region of globally renown agricultural productivity and biodiversity. The construction of 135 dams across the Mekong basin and the development of delta‐based flood prevention systems have caused public concern given possible threats on the stability of agricultural and ecological systems in the floodplains. Mekong dams store water upstream and regulate flow seasonality, while in situ flood prevention systems re‐distribute water retention capacity in the floodplains. The main aim of this paper is to evaluate possible impacts of the recent development of both hydropower dams and flood prevention systems on hydrological regimes in the Mekong floodplains. An analysis of measured daily and hourly water level data for key stations in the Mekong floodplains from Kratie to the river mouth in Vietnam was conducted. Hydropower dam information was obtained from the hydropower database managed by the Mekong River Commission, and the MODIS satellite imagery was used to detect changes in flooding extent related to the operation of flood prevention systems in the Vietnam Mekong Delta. Results indicate that the upper part of the floodplains, the Cambodian floodplains, may buffer upstream dam impacts to the Vietnam Mekong Delta. Flood prevention up to date has had the greatest effect on the natural hydrological regime of the Mekong floodplains, evidenced by a significant increase of water level rise and fall rates in the upper delta and causing water levels in the middle delta to increase. The development of flood prevention systems has also effected spatial distribution of flooding as indicated via a time series analysis of satellite imagery. While this development leads to increase localized agricultural productivity, our historical data analysis indicates that development of one region detrimentally affects other regions within the delta, which could increase the risk of future conflicts among regions, economic sectors and the ecological value of these important floodplains. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

边坡负压排水非稳定流研究     

雷怡  帅飞翔  孙红月  张泽坤  熊超 《吉林大学学报(地球科学版)》2022,52(1):162-170

自启动负压排水方法是一种新兴的间歇性波动排水方法,为对该方法的实现机理进行理论研究,建立了可供解析研究的负压排水模型。先引入狄拉克函数表述负压排水模型中点汇的数理特性,并对此模型推求出潜水剖面二维流运动方程及潜水面边界条件;再使用二维傅里叶正逆变换求解负压排水模型的定解问题,得到负压排水渗流场解析解。设置两种工况分别计算了自启动负压排水方法下数值模拟和理论解得到的边坡浸润线曲线,并进行了对比分析。结果表明：在不同排水孔位置工况的3组条件中,排水孔位置越深,理论解误差越大,其中排水孔位置为（24,10）时,靠近排水孔区域理论解与数值模拟结果误差最大;在排水孔位置固定、不同初始水头高度工况的3组条件中,左、右水头越高,理论解误差越大,其中左水头为28 m、右水头为8 m时,理论解与数值模拟结果误差最大。该自启动负压排水渗流场解析解在简化条件下的浸润线理论解与数值模拟结果吻合度较高。  相似文献   

Participants’ livelihoods compatible with conservation programs: evidence from China’s grain-for-green program in northern Shaanxi Province     

Dang  Xiaohu  Zhang  Miao  Xia  Zidun  Fan  Liangxin  Liu  Guobin  Zhao  Gaochang  Tao  Rui  Wei  Xuexiao 《GeoJournal》2021,86(4):1639-1655

GeoJournal - As the largest conservation program and payments for ecosystem services in China, the grain-for-green program (GGP) has substantially changed land use and cover, and reduced soil...  相似文献   

近53年石家庄地区气温稳定通过10℃的农业气候资源变化特征     

吴云龙  李丽平  王书冰  党红凯 《气象科技》2015,43(5):945-952

以17个气象站1960—2012年的观测资料,利用趋势分析, Mann Kendall检验,Morlet小波分析等方法,分析了石家庄地区气温稳定通过10 ℃的农业气候资源变化特征,结果表明：近53年气温稳定通过10 ℃的初日以14 d/10a的趋势提前,终日以1.1 d/10a的趋势后延,持续日数以2.5 d/10a的趋势增加,积温以64.5 ℃〖DK〗·d/10a的趋势增加,降水量无明显变化,日照时数以53.4 h/10a的趋势减少;各要素的时间序列除降水外均存在不同程度的突变,终日、持续日数、积温以及日照时数的突变较为显著,终日在2007年后后延显著,持续日数在1998年后显著增多,积温在2000年后显著增加,日照时数在1993年后显著减少;通过Morlet小波分析发现,各要素在近53年中存在周期性变化规律,初日和期间积温存在准2～4年的振荡周期,终日存在准2～3年的振荡周期,持续日数存在准2年的振荡周期。降水量存在准3年和准3～7年的振荡周期,日照时数存在准2～3年的振荡周期。石家庄地区气温稳定通过10 ℃的农业气候资源变化使作物的生长发育提前,生长周期变短,日照时数减少对作物生长有一定的不利影响。  相似文献   

Molecular characterizations of oxytetracycline resistant bacteria and their resistance genes from mariculture waters of China   总被引：1，自引：0，他引：1  

Dang H  Zhang X  Song L  Chang Y  Yang G 《Marine pollution bulletin》2006,52(11):1494-1503

Oxytetracycline-resistant bacteria were isolated from a mariculture farm in China, and accounted for 32.23% and 5.63% of the total culturable microbes of the sea cucumber and the sea urchin rearing waters respectively. Marine vibrios, especially strains related to Vibrio splendidus or V. tasmaniensis, were the most abundant resistant isolates. For oxytetracycline resistance, tet(A), tet(B) and tet(D) genes were detected in both sea cucumber and sea urchin rearing ponds. The dominant resistance type for V. tasmaniensis-like strains was the combination of both tet(A) and tet(B) genes, while the major resistance type for V. splendidus-like strains was a single tet(D) gene. Most of the sea cucumber tet-positive isolates harbored a chloramphenicol-resistance gene, either cat IV or cat II, while only a few sea urchin tet-positive isolates harbored a cat gene, actually cat IV. The coexistence of tet and cat genes in the strains isolated from the mariculture farm studied was helpful in explaining some of the multi-resistance mechanisms.  相似文献   

陕北侏罗纪煤田地下水保护对策与开采利用方案 研究          下载免费PDF全文

党学亚  张茂省  董英  顾小凡 《地学前缘》2010,17(6):200-207

矿山开采活动中地下水与生态环境保护是需要综合利用多学科思想与理论解决的难题,仅从采矿工程学角度难以解决根本问题。文中从生态水文地质学的角度,针对陕北采煤安全必须疏排水和陕北能源基地建设亟须水资源支撑的现状,提出了通过充分地利用煤田地下水满足强劲用水需求来保护水资源的对策,并从矿区水文地质结构、地下水循环条件出发,根据矿区植被生态风险区划、采煤影响地下水区划,提出了建立保护矿山水资源的采煤秩序、不同阶段地下水保护与开发利用区划以及矿山掘进过程中保护性开采地下水的水源地布局规划原则与建设方案。  相似文献