The relationship between zooplankton,conductivity and lake-water ionic composition in 111 lakes from the Interior Plateau of British Columbia,Canada

Zooplankton collected from vertical net tows were related to the environmental variables from 98 lakes from the Interior Plateau of British Columbia. Canonical correspondence analysis showed that both salinity and ionic composition (pH and Mg) of the lake-water made major and significant contributions to the first two ordination axes (=0.42 and 0.11 respectively,P<0.05). BothArtemia franciscana andMoina hutchinsoni had their highest relative abundance in meso-hypersaline waters. However,Artemia franciscana preferred waters that were higher in Mg and Ca, whileMoina hutchinsoni was found in waters that were lower in Mg and Ca. Similarly, at intermediate salinities,Daphnia pulex and the calanoid copepods preferred waters slightly lower in Mg and Ca, whereasCeriodaphnia laticaudata andSimocephalus spp. were relatively more common in waters higher in Mg and Ca. Because the freshest lakes studied varied much less in ionic composition, the zooplankton in these lakes did not show a preference to ionic composition. As expected, multi-generic groups, such as the calanoid copepods, cyclopoid copepods and nauplii, had wider tolerances to conductivity than groups identified to lower taxonomic levels. Significant weighted-averaging regression and calibration models of conductivity were developed based on zooplankton species composition from the study lakes (r ²=0.56,P<0.05). Samples composed largely of multi-generic taxa yielded the worst estimates of salinity in the reconstruction model. This study suggests that zooplankton community composition may be developed into a useful proxy for paleosalinity reconstruction.     

Lake Issyk-kul,Kirgizia

The main limnological features of Lake Issyk-kul are described. The lake is a large (6,236 km²), deep (z_m, 668 m), closed lake in eastern Kirgizia. It lies at ∼1,607 m above sea level, but water-levels have been dropping since the last century. It is slightly saline (salinity, ∼6g L⁻¹), with Na⁺, Mg²⁺, Cl⁻ and SO ₄ ²⁻ the dominant ions. Nutrient levels are low and the lake is considered ultra-oligotrophic. Characeae dominate the macrophytes. About 300 and 117 taxa of, respectively, phytoplankton and zooplankton have been identified, withArctodiaptomus salinus the most numerous in the zooplankton. Chironomids dominate the benthos. Several endemic taxa of fish occur, of whichLeuciscus bergi was dominant until the 1970s. The fish fauna has been supplemented by many introduced species. Three mysids were introduced in 1965–8 and are now a significant part of the ecosystem. The present annual fish catch permitted is 320 t. The most important value of the lake is as a recreational resource. To promote and sustain this value requires careful, ongoing management. The most significant threats to the lake are local pollution, visitor pressure, and declining water-levels.     

腾格里地区盐湖的盐类沉积特征

腾格里沙漠122个盐湖分为石盐、石盐-芒硝、石盐-白钠镁矾及芒硝(石膏)4种类型。盐湖含盐系厚度一般4～9m,总体呈现下部为含盐碎屑沉积,上部以盐类沉积为主,构成储卤层,卤水赋存其中,由湖岸至湖心储卤层厚度增长。含卤层理渐小,卤水含KCl渐高。盐湖中矿物主要为碳酸盐矿物,以芒硝、石膏为主的硫酸盐矿物、石盐以及粘土矿物。盐湖卤水以晶间卤水为主。许多卤水含K+大于2g/L。K+含量最高的红盐池,平均含量达19.14g/L。对钾矿而言,在盐湖分布相对集中地区,有一定的综合开发利用前景。     

胶东半岛海产养殖地下咸水分布特征及开发利用现状

胶东半岛位于山东省胶莱河以东,区内海岸线全长约1 700km,沿海滩涂面积约500km2。由于该区特殊的自然地理和地质环境条件,赋存有适宜海产养殖的地下咸水。该文依据大量的基础资料,阐述了胶东半岛区内海产养殖地下咸水的分布特征、富水地段资源量及开发利用现状,并针对开发利用中引发的地质环境问题提出了相应的保护建议,对于指导该区海产养殖地下咸水资源科学合理开发利用具有重要的意义。     

Hydrogeological investigation of Chappice Lake, southeastern Alberta: Groundwater inputs to a saline basin

Sediment cores from Chappice Lake, a hypersaline, groundwater-fed lake in southeastern Alberta, have been used in previous studies to reconstruct Holocene climate using lake levels as a source for proxy climate data. This assumes that the lake is fed by a shallow groundwater system sensitive to changes in climate. In this study we use the dynamics and chemistry of groundwater entering the lake to test this hypothesis.Groundwater inputs calculated from historical records using a simple water budget were highest during periods when the precipitation deficit was high. Over specific time intervals, the expected relationship between lake volumes and climate were not always found. Feedback loops between lake levels and groundwater input, and time lags within the system are the mechanisms proposed to explain these discrepancies.Field measurements suggest discharge of a local surficial groundwater system. Slug tests reveal a high conductivity system (K = 10-5 m/s) surrounding the lake. Hydraulic heads measured in standpipe, multilevel and minipiezometers installed around Chappice Lake show that the lake is situated in a closed hydraulic head contour. Hydraulic heads and water table elevations show strong annual fluctuations corresponding to seasonal changes in recharge. Horizontal hydraulic gradients measured in areas of groundwater springs indicate a strong horizontal component of flow towards the lake. Vertical hydraulic gradients are low and indicate the upward flow of water consistent with the discharge of a shallow, surfical groundwater system.Groundwater sampled from deposits surrounding Chappice Lake and springs feeding the lake have compositions similar to both shallow surficial aquifers and bedrock aquifers suggesting that the lake may be receiving inputs from both sources. However, evaporation simulations using PHRQPITZ, show that the evaporation of water typical of bedrock aquifers result in a mineral assemblage and brine composition different from that found at Chappice Lake. This suggests that discharge of a regional groundwater system can be eliminated as a dominant source over the lake's history. Evaporation simulations suggest that evaporation of groundwater from shallow surficial deposits can best explain the present mineral assemblage and brine chemistry and were likely the dominant source of water to the lake.Bedrock and shallow surficial groundwater sources have different chemistries and isotopic compositions. In hydrogeological settings such as Chappice Lake where more than one source may contribute to the lake, the relative importance of the different sources may change with changes in climate. If the source water composition to the lake changes, identifying changes in climate or hydrology based on changes in the composition of the lake preserved in sediment core will be made more difficult. This may complicate paleoclimate and paleohydrological reconstructions that rely on mineralogical and isotopic data.     

中国板块构造与盐类矿产

中国大陆的华北、塔里木、准噶尔－兴安、华南及甘青藏等五大板块发展过程中于地块边缘活动带、陆间裂谷、陆内裂谷等场所生成的含盐盆地，沉积了各时期（Ｏ、Ｃ、Ｔ、Ｊ－Ｅ和Ｑ）盐类矿床。通过分析对比认为，甘青藏板块兰坪－思茅拗陷带（Ｊ２－Ｅ１、Ｑ），塔里木板块（Ｃ、Ｋ－Ｅ、Ｑ），华北板块（Ｏ２），华南板块（Ｔ１－２）为成钾有利地带，中国东部众多的Ｋ－Ｅ红层盆地中成钾条件较差     

陕北奥陶纪盐盆马五6时期东、西部盐坳沉积环境对比研究

陕北奥陶纪盐盆位于鄂尔多斯盆地伊陕斜坡东部。研究表明:马五6亚期,盐盆存在"两坳一隆"的构造格局,即东、西部盐坳和中部隆起,东、西部盐坳在钾矿化情况、溴氯系数反映的水体咸化趋势方面初步显示了陕北盐盆东、西部沉积环境的差异。本文通过东、西部盐坳典型钻井马五6层位沉积学分析,揭示了马五6时期东、西部盐坳在水体深度变化、浓缩趋势、含钾量、淡化层段厚度、陆源物质输入方面均存在差异。其中,西部盐坳受海水影响大,水体变浅且持续淡化,泥质分布反映陆源物质贡献少,对钾盐的沉积与保存均十分不利。而东部盐坳受海水影响小,与西部盐坳水体联通性差,在马五6时期环境更为封闭,具体表现为淡化夹层分布数量少、厚度薄的特征;水体持续变深并浓缩咸化;泥质夹层较多,反映了相较于西部,陆源物质对其影响更大,上述特点为钾盐沉积提供了有利的地球化学条件及可容空间。东、西部盐坳沉积环境对比表明东部盐坳对成钾更为有利。     

A note on the chemical composition of lake water in the Laguna Amarga,a saline lake in Patagonia,Chile

The chemical composition of lake water in Laguna Amarga, a small, shallow, saline lake near the Torres del Paine National Park (at 51°S), Chilean Patagonia, was studied in January, 1993. The water was strongly alkaline (pH 9.4) conductivity was 71.4 mS cm^–1, and salinity was 77 g L^–1. The major ions were sodium and sulphate.     

福建闽江口外海岸植物生态

记录了福建闽江口266种海岸高等植物,其中草本占70.2%、灌木占21.4%、藤本和乔木占8.4%.喜盐种在河口的内侧、中区和外侧占总数的百分比分别为5.7%,6.8%和11.8%.二叶红薯、南方碱蓬和番杏是盐碱土的指示种.在内侧近淡水区有繁茂的咸水草、芦苇和芦竹     

Colorado’s Millennial Generation: Youth Perceptions and Experiences of Nature

Abstract

This study uses survey and focus group methods to explore attitudes toward and experiences of nature among millennial-aged students in northern Colorado. First, results confirm that young people possess a strong interest in the outdoors yet time, transportation, and new technologies hamper their ability to visit public lands and outdoor spaces. Second, respondents experience nature in ways more mediated by new technologies such as cell phones and nature DVDs. Third, citizen science and active learning show promise as techniques for returning young people to the outdoors. The challenge lies in teaching young people to reimagine the outdoors not as elsewhere or out there but as a backyard geographic space.