富营养化对湖泊消费者群落碳源和氮源的影响——以白洋淀为例

富营养化对湖泊生态系统能流和物流的影响具有不确定性,多数研究仅关注富营养化对浅水湖泊食物网结构和功能的影响,而富营养化对消费者群落碳源和氮源的影响及其时空分异特征较少关注.鉴于此,本研究选取华北平原最大的浅水富营养化湖泊——白洋淀为研究区,依据生境理化参数将白洋淀划分为3类生境(生境1(Ⅰ和Ⅱ区)主要遭受上游府河废水排放影响;生境2(Ⅴ、Ⅶ和Ⅷ区)主要遭受水产养殖和生活污水的影响;生境3(Ⅲ、Ⅳ和Ⅵ区)遭受人为干扰较小).在2018年4月和8月分别收集了浮游生物、底栖生物和鱼类样品,运用碳、氮稳定同位素技术定量估算3类生境中底栖和浮游生物对消费者群落碳源和氮源贡献百分比的时空分异特征;同时收集水体和沉积物样品进行常规理化参数分析,明晰富营养化对白洋淀消费者群落碳源和氮源贡献百分比的影响.结果表明:1)就水体和沉积物理化参数季节变化而言,除pH相对稳定外,化学需氧量(COD)、沉积物氨氮(NH3-Ns)、总氮(TN)和沉积物总磷(TPs) 4月高于8月,而其他理化参数则8月高于4月;就空间分布而言,温度(T)、水深(WD)、溶解氧(DO)和沉积物总碳(TCs)值在生境3中最高,而其他理化...     

Numerical simulation of strong ground motion for the <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript>8.0 Wenchuan earthquake of 12 May 2008

The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morphological factors affecting the seismic hazard, we simulated the strong ground motion caused by the earthquake, incorporating three-dimensional (3D) earth structure, finite-fault rupture, and realistic surface topography. The simulated ground motions reveal that the fault rupture and basin structure control the overall pattern of the peak ground shaking. Large peak ground velocity (PGV) is distributed in two narrow areas: one with the largest PGV values is above the hanging wall of the fault and attributed to the locations of fault asperities and rupture directivity; the other is along the northwestern margin of the Sichuan Basin and caused by both the directivity of fault rupture and the amplification in the thick sediment basin. Rough topography above the rupture fault causes wave scattering, resulting in significantly larger peak ground motion on the apex of topographic relief than in the valley. Topography and scattering also reduce the wave energy in the forward direction of fault rupture but increase the PGV in other parts of the basin. These results suggest the need for a localized hazard assessment in places of rough topography that takes the topographic effects into account. Finally, had the earthquake started at the northeast end of the fault zone and ruptured to the southwest, Chengdu would have suffered a much stronger shaking than it experienced on 12 May, 2008. Supported by the U.S. National Science Foundation (Grant Nos. EAR 0738779 and OCE 0727919), the National Basic Research Program of China (Grant No. 2004CB418404), and partially by the National Nature Science Foundation of China (Grant No. 40521002)     

GRAPES区域模式水汽平流方案的比较与改进

与欧拉显式时间差分方法相比,GRAPES区域模式采用半隐半拉格朗日时间差分方案可增加时间步长且不影响稳定性,而且模式积分可有较高的计算效率和准确性。半拉格朗日法需要用到内插算法来预测下一时刻的值,对于水汽场的内插值来说,常常会造成预报值的过饱和或者是负值,需要进行特殊处理。比较GRAPES模式的准单调半拉格朗日方案(QMSL)和高精度正定保形方案(PRM),分析模式的降水预报、形势预报,同时初步总结了两方案的优缺点。在参考LCSL(Linear Constraint Semi-Lagarangain)方案的基础上,改进QMSL方案,通过连续试验运行,表明新方案基本稳定可靠,对于降水预报、形势预报有一定的改进,在台风预报试验中也有良好的表现。     

蒙自喀斯特断陷盆地边坡与盆缘的露石差异性

喀斯特露石常常占据一定比例的地表面积,且具有许多已知或未知的水文—生态功能,对于喀斯特地区的植被恢复和环境改善发挥着重要的作用。本实验运用样线法和拍照法识别喀斯特断陷盆地不同位置(盆缘和盆地边坡)露石的数量特征和外部形态特征,同时比较了两种方法测量样地岩石裸露率的精准度。结果发现:盆地边坡与盆缘的露石数量和外部特征存在显著差异,盆缘露石分布密度(0.54个·m-2)>盆地边坡(0.39个·m-2);但盆地边坡露石的长宽比大于盆缘,单体占地面积为盆缘露石的两倍,接近40%的盆地边坡露石与山体等高线平行。样线法和拍照法测量样地岩石裸露率的结果存有差异,但并不显著,且这种差异呈现出随着岩石裸露率的增加而逐渐增加的趋势,拍照测量结果具有较小的变异系数。这些结果说明了研究区露石具有较强的空间异质性,对解释地表水土运移规律和植物分布提供重要参考。拍照法能准确地测量岩石裸露率,并提供露石外部形态特征的精准数据,可以作为喀斯特样地露石调查的新方法加以推广。     

Progress in the Research on Benefit-sharing and Ecological Compensation Mechanisms for Transboundary Rivers

Transboundary rivers have important geopolitical and geo-economic connotations, but riparian states of transboundary rivers are often driven by their own rapid population growth and economic development to be-come involved in regional conflicts about the development and use of water resources. Therefore, finding a balance between the need for fair and reasonable development of water resources and the effective protection of environment from an ecological perspective has become a major problem faced by the international community. This paper begins with consideration of international water laws related to transboundary rivers and then reviews advances in the research on benefit-sharing, ecological compensation mechanisms, and adaptive management systems. We believe that existing international water laws form a complete legal system and that more attention needs to be paid to transboundary cooperation and sustainable water resource use. With respect to how transboundary water conflicts are resolved, there is a trend to move away from single water resource allocation (a zero-sum game) to benefit-sharing in order to achieve a win-win situation for riparian states, but there are still some difficulties in transboundary ecological compensation. In China, the central government has paid attention to horizontal ecological compensation between upstream and downstream, offering guidance to promote establishment of inter-province ecological compensation. Based on existing practice, horizontal ecological compensations are still in their infancy, small in scale, supported by a weak legal system, lacking market mechanisms to encourage their use and relying on fiscal transfers as the method of payment. In the future, China will need to intensify its research on legal system development, international cooperation, and benefit-sharing as these impact transboundary water resources. Because government can be seen as a management department with multiple identities (enabler, regulator and buyer), to improve adaptive transboundary ecological compensation mechanisms, government must develop as soon as possible data sharing platforms, standards of water consumption behaviors and intergovernmental policies (or ordinances).     

Application of the Response Surface Method for Optimization of Headspace Liquid Phase Microextraction of Trihalomethanes in Drinking Water

An optimized analysis method based on headspace liquid phase microextraction (HS‐LPME) and gas chromatography coupled with mass spectrometry was proposed for the determination of trihalomethanes (THMs) in drinking water. The response surface method (RSM) was used to optimize the extraction of THMs for analysis by HS‐LPME. The temperature, extraction time and NaCl concentration were found to be important extraction parameters. The coefficient of determination (R²) for the model was 94.97%. A high probability value (P < 0.0001) for the regression indicated that the model had a high level of significance. The optimum conditions were seen to be: temperature 42.0°C, NaCl concentration 0.30 g/mL, and extraction time 28 min. The response variable was the summation of the THMs chromatography peak areas and the reproducibility of this was investigated in five replicate experiments under the optimized conditions. The relative standard deviations (RSD%) of the THMs ranged from 8.0–11.6%. The limits of detection (LODs), based on a signal‐to‐noise ratio (S/N) of three ranged from 0.42–0.78 μg/L, and were lower than the maximum limits for THMs in drinking water established by the WHO.     

表面粗糙对渤海海冰热红外辐射方向特征的影响研究

热红外遥感技术使大范围、快速地监测渤海海冰表面温度成为可能。然而,目前绝大多数遥感器都是小视场角的,只对海冰在某个方向上的辐射能量进行了测量。由于自然界的海冰大多数都是高低起伏的、不平坦的,如果近似地认为遥感像元尺度内各部分温度是相同的,有时会带来较大误差。在盛冰期的渤海辽东湾东岸固定冰区,分别用3D激光扫描仪、热红外成像仪和自计温度计测量了渤海海冰的表面形状、辐射亮温和真实温度。结果表明,由于海冰表面粗糙,会形成三维非同温像元。同时,也会导致传感器在粗糙海冰的各个部分的局部观测天顶角与整体观测天顶角有所不同,造成粗糙海冰与平整海冰的方向辐射特征有较大差异,平整海冰更接近理想平面,粗糙海冰更接近朗伯面。     

长江入海口浅层沉积物中典型有机氯农药分布特征

对长江入海口包括江苏启东,上海崇明岛、长兴岛、横沙岛等地区的浅层沉积物中典型有机氯农药(OCPs)的分布情况进行了研究。采用气相色谱-电子捕获检测器进行检测,方法检出限为0.10 ng/g,回收率为62.4%～116.7%,精密度(RSD)为2.7%～8.3%。调查分析结果显示,长江入海口沿岸均存在轻度和中度的OCPs污染,主要检出物总滴滴涕(DDTs)浓度范围为1.22～626.43 ng/g。深度(0～80 cm)采样检测结果表明,研究区表层及深度样品中DDTs均有不同程度检出,浅层沉积物中DDTs在0～20 cm区域占检出总量的58.1%;其次是20～40 cm区域,DDTs占总量的30.8%;40～60 cm区域DDTs占总量的8.2%;60～80 cm区域DDTs占总量的2.9%,即浅层沉积物中DDTs主要集中在0～40 cm区域,部分点位40～80 cm能够检出少量DDTs。本研究提供的数据为该地区OCPs垂直分布提供参考。     

伊通盆地鹿乡断陷双阳组储层孔隙结构特征及其控制因素

通过对钻井岩芯及铸体薄片、扫描电镜观察,结合压汞分析测试,研究了伊通盆地鹿乡断陷双阳组储层的孔隙结构特征。结果表明:储层成因类型主要为扇三角洲砂体,部分为水下扇砂体;储层砂体孔隙类型以次生溶蚀孔隙为主,部分为原生粒间孔隙,具体可见粒内溶孔、原生粒间孔和粒间溶蚀扩大孔等;孔隙喉道较小,分选不好,连通性差,总体为低孔低渗型储层,其中,双阳组二段储层略好于双三段,双一段最差。双阳组储层孔隙结构特征主要受砂体成因类型和成岩作用的控制,此外,岩石粒度和构造作用也对孔隙结构有一定的控制作用。     

跨季节蓄热型地源热泵热传递规律研究

基于有限元分析法,建立了准三维非稳态传热模型。在试验验证的基础上,分析了跨季节蓄热型地源热泵蓄热过程中土壤温度、单位井深换热量、热作用半径随热泵运行时间的变化规律,讨论了土壤结构、入口水温、入口质量流量、热泵运行模式等对土壤传热规律的影响,并研究了土壤热平衡问题。结果表明:同一半径不同深度处,土壤温度增长幅度随土壤热扩散率的增加而增大;土壤热作用半径随热泵运行时间及入口水温的升高而增加,并逐渐趋于稳定;间歇运行模式下,地埋管附近土壤温度及换热量均呈波动式变化,且当径向距离大于0.3 m时,与连续模式一致;在满足换热量的情况下,流体质量流量不宜过大;系统运行一个周期（360 d）后土壤温度基本可以恢复,且流体入口温度不宜低于40 ℃。