Saline groundwater seepage zones and their impact on soil and water resources in the Spicers Creek catchment,central west,New South Wales,Australia

Saline seepage zone development and hence dryland salinity is a major environmental problem which many arid to semiarid landscapes in Australia are experiencing. Due to the geological complexity of the regional aquifer system and the heterogeneous nature of the local groundwater system, each groundwater seepage zone in the Spicers Creek catchment, central west, New South Wales, Australia possesses different mechanisms which control its development. Saline seepage zones have formed adjacent to a fault zone, and two experimental sites were established through these groundwater discharge zones to understand geochemical processes which have led to the development of soil sodicity, gully erosion and the flushing of salts into the surface water systems. Seepage zone groundwaters contain a distinctive geochemical signature with elevated concentrations of Na, Cl, HCO₃, Ca, Sr, B, As and Li. The mixing of deep saline groundwaters together with ion exchange processes lead to a distinctive seepage zone groundwater chemistry being developed. Altering the landscape features within this rural groundwater system has developed water toxicity for crops, soil sodicity leading to land degradation, and waterlogging problems.     

Occurrence of selected estrogens in mangrove sediments

This paper presents results related to the occurrence and distribution of estrogens along the Brazilian coast. Three mangrove areas were chosen to evaluate the presence of estrogens in surface sediments of mangrove forests. The presence of estrogens was observed in all studied sites. 17-α-Ethinylestradiol (EE2), a synthetic estrogen, was the most common and has been found in higher concentration (0.45-129.78 ng/g) compared to 17-β-estradiol (E1) and estrone (E2) (both being natural estrogens). The concentrations of E1 and E2 ranged from 0.02 to 49.27 ng/g and 0.03 to 39.77 ng/g, respectively. Theoretically, under anaerobic conditions EE2 can be reduced to E1 even in environments such as sediments of mangrove forests, which are essentially anaerobic. Even if the concentrations of estrogens seem to be insignificant in some samples, the effects remain uncertain.     

Holocene climate vs. catchment forcing on a shallow,eutrophic lake in eastern Poland

This paper presents a sedimentary record from Lake ?ukie located in the southeastern part of the Central European Plain, beyond the reach of the maximum extent of the last glaciation. The lake has thermokarstic origin and developed during the last glacial termination due to subsidence of the sub‐Quaternary carbonate basement triggered by permafrost thawing. A sediment core was investigated to reconstruct water trophic state and lake depth changes during the Holocene. We aimed at showing the relationship between ecological and geochemical changes in the lake and regional/supraregional climatic and hydrological trends throughout the Holocene. Results of subfossil Cladocera analysis were combined with data on the geochemistry and stable C and O isotopes in sedimentary carbonates. Isotopic and geochemical proxies helped to detect sources of sedimentary particles in the lake and thus to reconstruct changes in the intensity of atmospheric and catchment processes (e.g. precipitation and surface runoff). The Cladocera analysis results indicated endogenic processes in the lake such as trophic changes. Our data revealed that Lake ?ukie has always been a rather eutrophic water body and the periods of particularly high productivity were in the lower Preboreal and upper Subatlantic. Periods of increased water depth were recorded in the lower Preboreal, lower Boreal and upper Subboreal, whereas low water stands were obtained during the late Preboreal, late Boreal, late Atlantic and Atlantic/Subboreal transition as well as during the lower Subboreal. The sediment succession from Lake ?ukie provides the first full Holocene record of carbon and oxygen stable isotopes in lacustrine carbonates from the eastern part of the Central European Lowland. The record is characterized by uncommonly high δ¹³C and δ¹⁸O values of the carbonates resulting from a combination of within‐lake processes and dissolution of the carbonate bedrock of Cretaceous age. The impact of the old carbonates on isotope values was helpful in the reconstruction of the catchment forcing on the lake.     

Real-time precise point positioning augmented with high-resolution numerical weather prediction model

GPS Solutions - The tropospheric delay is one of the major error sources in precise point positioning (PPP), affecting the accuracy and precision of estimated coordinates and convergence time,...     

The Manso Glacier drainage system in the northern Patagonian Andes: an overview of its main hydrological characteristics

The Manso Glacier (~41°S, 72°W), in the northern Patagonian Andes of Argentina, is a regenerated glacier that, like many other glaciers in the region and elsewhere, has been showing a significant retreat. Glacial melt water feeds the Manso Superior River, which, before crossing the Andes to reach a Pacific outfall, flows through the Mascardi (a deep, oligotrophic and monomictic lake) and significantly smaller Hess and Steffen lakes. Harmonic analysis of Mascardi's lake level series suggests that the El Niño‐Southern Oscillation signal has been strong during the 1985–1995 decade but has grown weaker during the initial decade of the 21st century. Hydrological trend analyses applied in data recorded in the uppermost reaches show a monthly and annual decreasing trend in the Manso Superior River discharge series and Mascardi's lake level, which are connected with both, decreasing melt water discharge and (austral) wintertime atmospheric precipitation. Downstream, the decreasing signal initially looses statistical significance and then, when flowing through Steffen Lake, reverses the lake level trend that becomes significantly positive. This suggests that, on its way to the Pacific Ocean, the Manso River receives abundant Andean snow melt water and atmospheric precipitation, which are sufficient to obliterate the negative trend recorded in the uppermost reaches. The reason for this local phenomenon is that the Manso is an antecedent river (aka superposed stream), and hence, the valley crossing the Andes allows the incursion of Pacific humidity that modifies the hydrological regime several hundred kilometres inland. Copyright © 2012 John Wiley & Sons, Ltd.     

The ocean response to climate change guides both adaptation and mitigation efforts

The ocean's thermal inertia is a major contributor to irreversible ocean changes exceeding time scales that matter to human society. This fact is a challenge to societies as they prepare for the consequences of climate change, especially with respect to the ocean. Here the authors review the requirements for human actions from the ocean's perspective. In the near term (～2030), goals such as the United Nations Sustainable Development Goals (SDGs) will be critical. Over longer times (～2050–2060 and beyond), global carbon neutrality targets may be met as countries continue to work toward reducing emissions. Both adaptation and mitigation plans need to be fully implemented in the interim, and the Global Ocean Observation System should be sustained so that changes can be continuously monitored. In the longer-term (after ～2060), slow emerging changes such as deep ocean warming and sea level rise are committed to continue even in the scenario where net zero emissions are reached. Thus, climate actions have to extend to time scales of hundreds of years. At these time scales, preparation for “high impact, low probability” risks — such as an abrupt showdown of Atlantic Meridional Overturning Circulation, ecosystem change, or irreversible ice sheet loss — should be fully integrated into long-term planning.摘要在全球变化背景下, 海洋的很多变化在人类社会发展的时间尺度上 (百年至千年) 具有不可逆转性, 海洋巨大的热惯性是造成该不可逆性的主要原因. 这个特征为人类和生态系统应对海洋变化提出一系列挑战. 本文从海洋变化的角度总结了人类应对气候变化的要求, 提出需要进行多时间尺度的规划和统筹. 在近期 (到2030年) , 实现联合国可持续发展目标至关重要. 在中期 (2050–2060年前后) , 全球需要逐步减排并实现碳中和目标. 同时, 适应和减缓气候变化的行动和措施必须同步施行; 全球海洋观测系统需要得以维持并完善以持续监测海洋变化. 在远期 (在2060年之后) , 即使全球达到净零排放, 包括深海变暖和海平面上升在内的海洋变化都将持续, 因此应对全球变化的行动需持续数百年之久. 在该时间尺度, 应对“低概率, 高影响”气候风险 (即发生的可能性较低, 但一旦发生影响极大的事件带来的风险, 例如: 大西洋经圈反转环流突然减弱, 海洋生态系统跨过临界点, 无可挽回的冰盖质量损失等) 的准备应充分纳入长期规划.     

A simple approach to adjust tidal forcing in fjord models

To model currents in a fjord accurate tidal forcing is of extreme importance. Due to complex topography with narrow and shallow straits, the tides in the innermost parts of a fjord are both shifted in phase and altered in amplitude compared to the tides in the open water outside the fjord. Commonly, coastal tide information extracted from global or regional models is used on the boundary of the fjord model. Since tides vary over short distances in shallower waters close to the coast, the global and regional tidal forcings are usually too coarse to achieve sufficiently accurate tides in fjords. We present a straightforward method to remedy this problem by simply adjusting the tides to fit the observed tides at the entrance of the fjord. To evaluate the method, we present results from the Oslofjord, Norway. A model for the fjord is first run using raw tidal forcing on its open boundary. By comparing modelled and observed time series of water level at a tidal gauge station close to the open boundary of the model, a factor for the amplitude and a shift in phase are computed. The amplitude factor and the phase shift are then applied to produce adjusted tidal forcing at the open boundary. Next, we rerun the fjord model using the adjusted tidal forcing. The results from the two runs are then compared to independent observations inside the fjord in terms of amplitude and phases of the various tidal components, the total tidal water level, and the depth integrated tidal currents. The results show improvements in the modelled tides in both the outer, and more importantly, the inner parts of the fjord.     

Evaluation of the Global Mean Sea Level Budget between 1993 and 2014

Evaluating global mean sea level (GMSL) in terms of its components—mass and steric—is useful for both quantifying the accuracy of the measurements and understanding the processes that contribute to GMSL rise. In this paper, we review the GMSL budget over two periods—1993 to 2014 and 2005 to 2014—using multiple data sets of both total GMSL and the components (mass and steric). In addition to comparing linear trends, we also compare the level of agreement of the time series. For the longer period (1993–2014), we find closure in terms of the long-term trend but not for year-to-year variations, consistent with other studies. This is due to the lack of sufficient estimates of the amount of natural water mass cycling between the oceans and hydrosphere. For the more recent period (2005–2014), we find closure in both the long-term trend and for month-to-month variations. This is also consistent with previous studies.