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991.
Lorna Louise Thurston Erik Schiefer Nicholas P. McKay Darrell S. Kaufman 《水文研究》2020,34(19):3910-3927
Seasonal suspended sediment transfer in glaciated catchments is responsive to meteorological, geomorphological, and glacio-fluvial conditions, and thus is a useful indicator of environmental system dynamics. Knowledge of multifaceted fluvial sediment-transfer processes is limited in the Alaskan Arctic – a region sensitive to contemporary environmental change. For two glaciated sub-catchments at Lake Peters, northeast Brooks Range, Alaska, we conducted a two-year endeavour to monitor the hydrology and meteorology, and used the data to derive multiple-regression models of suspended sediment load. Statistical selection of the best models shows that incorporating meteorological or temporal explanatory variables improves performances of turbidity- and discharge-based sediment models. The resulting modelled specific suspended sediment yields to Lake Peters are: 33 (20–60) t km−2 yr−1 in 2015, and 79 (50–140) t km−2 yr−1 in 2016 (95% confidence band estimates). In contrast to previous studies in Arctic Alaska, fluvial suspended sediment transfer to Lake Peters was primarily influenced by rainfall, and secondarily influenced by temperature-driven melt processes associated with clockwise diurnal hysteresis. Despite different sub-catchment glacier coverage, specific yields were the same order of magnitude from the two primary inflows to Lake Peters, which are Carnivore Creek (128 km2; 10% glacier coverage) and Chamberlin Creek (8 km2; 23% glacier coverage). Seasonal to longer-term sediment exhaustion and/or contrasting glacier dynamics may explain the lower than expected relative specific sediment yield from the more heavily glacierized Chamberlin Creek catchment. Absolute suspended sediment yield (t yr−1) from Carnivore Creek to Lake Peters was 27 times greater than from Chamberlin Creek, which we attribute to catchment size and sediment supply differences. Our results provide a foundational understanding of the current sediment transfer regime and are useful for predicting changes in fluvial sediment transport in glaciated Alaskan Arctic catchments. 相似文献
992.
作为海洋中最丰富的有机含硫化合物之一,二甲基巯基丙酸内盐(DMSP)不仅在浮游植物细胞内具有重要的生理生化及生态功能,同时也是海洋微生物的重要营养物,其分解产物二甲基硫(DMS)还是海洋中最重要的还原态挥发性生源有机硫化物,因此DMSP的代谢在全球硫循环中扮演着重要角色。细菌可通过脱甲基与裂解这两条途径降解海水中的DMSP,从而决定硫元素是以含硫蛋白形式进入微生物食物网还是以DMS形式进入大气。截至目前,在高纬度北极海域开展的有关细菌降解DMSP的相关研究报道很少。本文采用荧光定量PCR技术,首次对北极王湾夏季(2015及2016年)海水中涉及细菌降解DMSP的两条主要代谢途径中的脱甲基酶基因dmdA及裂解酶基因dddP的丰度及分布进行了检测。结果显示, 2015—2016年海水中DMSP降解酶基因(dmdA、dddP)与细菌16S rRNA基因的丰度比值的平均值分别为0.25%±0.31%、0.32%±0.58%。2015年水样中,除K5站位的dddP基因之外,表层水中dmdA及dddP的丰度相对值从湾口至湾内均呈递增趋势。但2016年的结果却显示出很大差异:湾口附近dmdA基因丰度相对值总体高于湾内;表层水中的dddP基因丰度相对值变化趋势不明显,而深层水中dddP基因丰度相对值从湾口到湾内总体呈递减趋势。本次研究的结果初步表明,含有DMSP降解基因的浮游细菌在王湾夏季水体中丰度很低,而且参与不同代谢途径的DMSP降解菌在海水中的时空分布存在很大变化。对于王湾水域中细菌参与DMSP分解代谢及其在当地硫元素循环中的生态地位的进一步认识,尚待后续研究工作的深入开展。 相似文献
993.
With the emergence of the concept of cultural routes, researchers have increasingly turned their attention to the sustainable development of tourism along cultural routes. The needs for community participation and the ongoing provision of benefits of stakeholders are characteristics of cultural routes. Therefore, the importance of cooperative relations and systematic development among stakeholders in tourism activities along cultural routes has become a subject of interest. This paper selects local government, tourism enterprises and local community residents, all of which play a key role in the Ancient Tea Horse Road cultural route in the south of Yunnan, as the main stakeholders. We use game theory to construct a model to trace interactions between local government and tourism enterprises, between tourism enterprises and community residents, and between local government and community residents. The paper then analyzes the different interests of the three parties and key factors that influence them in the game process. This provided a certain scientific basis for the win-win decisions regarding tourism development made by the three parties. Our results show that the final decision choices of the three parties depend on the initial payoff matrix of the game, and the influence of key parameters. When making decisions about tourism, the government should respect the wishes of local residents, strengthen protections of local traditions, manage the unreasonable behavior of tourism enterprises as they develop tourism, and develop appropriate penalties for violations of regulations. When tourism enterprises carry out tourism development, they should let community residents take the initiative and fully participate in tourism activities, and be sure that income from tourism is fed back to local residents, to ensure that tourism is mutually beneficial. The study shows that conflicts among the three parties originated mainly from differences in interests, but that the three parties also shared common interests. With a goal of coordinating interests, we can establish relevant mechanisms, follow the principle of interest realization, attach importance to supervision and management, strengthen community participation and decision-making, and realize win-win results for the three parties. 相似文献
994.
Evaluating the hydrological and hydrochemical responses of a High Arctic catchment during an exceptionally warm summer 下载免费PDF全文
Daniel Lamhonwah Melissa J. Lafrenière Scott F. Lamoureux Brent B. Wolfe 《水文研究》2017,31(12):2296-2313
The Arctic has experienced substantial warming during the past century with models projecting continued warming accompanied by increases in summer precipitation for most regions. A key impact of increasing air surface temperatures is the deepening of the active layer, which is expected to alter hydrological processes and pathways. The aim of this study was to determine how one of the warmest and wettest summers in the past decade at a High Arctic watershed impacted water infiltration and storage in deeply thawed soil and solute concentrations in stream runoff during the thaw period. In June and July 2012 at the Cape Bounty Watershed Observatory, we combined active layer measurements with major ion concentrations and stable isotopes in surface waters to characterize the movement of different runoff sources: snowmelt, rainfall, and soil water. Results indicate that deep ground thaw enhanced the storage of infiltrated water following rainfall. Soil water from infiltrated rainfall flowed through the thawed transient layer and upper permafrost, which likely solubilized ions previously stored at depth. Subsequent rainfall events acted as a hydrological flushing mechanism, mobilizing solutes from the subsurface to the surface. This solute flushing substantially increased ion concentrations in stream runoff throughout mid to late July. Results further suggest the importance of rainfall and soil water as sources of runoff in a High Arctic catchment during mid to late summer as infiltrated snowmelt is drained from soil following baseflow. Although there was some evaporation of surface water, our study indicates that flushing from solute stores in the transient layer was the primary driver of increased ion concentrations in stream runoff and not evaporative concentration of surface water. With warmer and wetter summers projected for the Arctic, ion concentrations in runoff (especially in the late thaw season), will likely increase due to the deep storage and subsurface flow of infiltrated water and subsequent flushing of previously frozen solutes to the surface. 相似文献
995.
The Hindcast of Winter and Spring Arctic and Antarctic Oscillation with the Coupled Climate Models 下载免费PDF全文
This study evaluates the ability of the global coupled climate models in hindcasting the Arctic Oscillation (AO) and Antarctic
Oscillation (AAO). The results show that the models can well simulate the spatial distribution of AO with better results in
winter than in spring. In the troposphere in spring, the simulation of AO on the whole is still relatively good with a comparatively
high correlation with the NCEP/NCAR reanalysis. The models can also well reproduce the spatial distribution of AAO throughout
the year at all levels of the troposphere, and the spatial simulation is better at 850 hPa than at the surface. Although the
simulation is better in winter than in other seasons, the seasonal variation is not so significant and the differences among
different models are relatively small. In addition, the capability of the models for “predicting” the AO and the AAO index
time series is limited, because only a few models can capture their observed interannual variability at the 95% significance
level. 相似文献
996.
南北涛动与南极涛动及北极涛动的相互作用 总被引:1,自引:0,他引:1
利用NCEP/NCAR再分析资料,分析了南北涛动(Interhemispheric Oscillation,IHO)与北极涛动(Arctic Oscillation,AO)和南极涛动(Antarctic Oscillation,AAO)的联系。分析表明:1)北极涛动(AO)、南极涛动(AAO)与全年各自半球中高纬度地表气压变化密切联系。其中,AO冬季强度最强,且在春季、冬季的影响范围大。而AAO对南半球中高纬的地表气压变动影响更为明显,其在夏季影响范围最大。2)南极涛动(AAO)与南北涛动(IHO)有很好的同期相关性,南极涛动可部分解释南北涛动的形成。IHO与AO存在不显著的负相关,南北半球中高纬大气运动具有相对独立性。3)南北涛动(IHO)与全球较大范围内的地面气压变化有关,而去除AAO信号后,夏季在南极地区原显著相关区显著减少,夏季AAO与IHO存在密切联系。4)南北涛动(IHO)主要与春季、秋季和冬季亚洲、欧洲北部地面气温关系密切。秋季最强,春季次之,冬季最弱。夏季IHO与全球地面气温没有较好的联系。亚欧大陆北部的热力作用可能部分地解释了南北涛动的形成。 相似文献
997.
998.
999.
Analysis of Atmospheric Boundary Layer Height Characteristics over the Arctic Ocean Using the Aircraft and GPS Soundings 下载免费PDF全文
Utilizing aircraft sounding data collected from the Surface Heat Budget of the Arctic Ocean (SHEBA, 1998) campaign, the authors evaluated commonly-used profile methods for Arctic ABL height estimation by validating against the’true’ABL height from aircraft sounding profiles, where ABL height is defined as the top of the layer with significant turbulence. Furthermore, the best performing method was used to estimate ABL height from the one-year GPS soundings obtained during SHEBA (October 1997-October 1998). It was found that the temperature gradient method produces a reliable estimate of ABL height. Additionally, the authors determined optimal threshold values of temperature gradient for stable boundary layer (SBL) and convective boundary layer (CBL) to be 6.5 K/100 m and 1.0 K/100 m, respectively. The maximum ABL height during the year was 1150 m occurred in May. Median values of Arctic ABL height in May, June, July, and August were 400 m, 430 m, 180 m, and 320 m, respectively. Arctic ABL heights are clearly higher in the spring than in the summer. 相似文献
1000.
This paper compares the ignitability of Troll B crude oil weathered under simulated Arctic conditions (0%, 50% and 90% ice cover). The experiments were performed in different scales at SINTEF’s laboratories in Trondheim, field research station on Svalbard and in broken ice (70-90% ice cover) in the Barents Sea. Samples from the weathering experiments were tested for ignitability using the same laboratory burning cell. The measured ignitability from the experiments in these different scales showed a good agreement for samples with similar weathering. The ice conditions clearly affected the weathering process, and 70% ice or more reduces the weathering and allows a longer time window for in situ burning. The results from the Barents Sea revealed that weathering and ignitability can vary within an oil slick. This field use of the burning cell demonstrated that it can be used as an operational tool to monitor the ignitability of oil spills. 相似文献