Impact of rock-water interactions and recharge on water resources quality of the Agadir-Essaouira basin,southwestern Morocco     

Al Yacoubi Latifa  Bouchaou Lhoussaine  Jaillard Etienne  Masrour Moussa  Ait Brahim Yassine  El Mouden Ahmed  Schneider Jana  Reichert Barbara 《Arabian Journal of Geosciences》2017,10(7):169

The Agadir-Essaouira area in the occidental High Atlas Mountains of Morocco is characterized by a semi-arid climate. The scarcity and quality of water resources, exacerbated by long drought periods, constitute a major problem for a sustainable development of this region. Groundwater resources of carbonate units within Jurassic and Cretaceous aquifers are requested for drinking and irrigation purposes. In this study, we collected 84 samples from wells, boreholes, springs, and rivers. Hydrochemical and isotopic data were used to examine the mineralization and origin of water, which control groundwater quality. The chemical composition of water seems to be controlled by water-rock interactions, such as dissolution of carbonates (calcite and dolomite), weathering of gypsum, as well as ion exchange processes, which explain the observed variability. Stable isotopes results show that groundwater from the mainly marly Cretaceous aquifer are submitted to an evaporation effect, while samples from the chiefly calcareous Jurassic aquifer indicate a meteoric origin, due to a rapid infiltration of recharge runoff through the karstic outcrops. The low values of δ¹⁸O and δ²H suggest a local recharge from areas with elevations ranging from 400 to 1200 m for the Cretaceous aquifer and from 800 to 1500 m for the Jurassic units.  相似文献   

A Snapshot of the Sun Near Solar Minimum: The Whole Heliosphere Interval     

Barbara J. Thompson  Sarah E. Gibson  Peter C. Schroeder  David F. Webb  Charles N. Arge  Mario M. Bisi  Giuliana de Toma  Barbara A. Emery  Antoinette B. Galvin  Deborah A. Haber  Bernard V. Jackson  Elizabeth A. Jensen  Robert J. Leamon  Jiuhou Lei  Periasamy K. Manoharan  M. Leila Mays  Patrick S. McIntosh  Gordon J. D. Petrie  Simon P. Plunkett  Liying Qian  Peter Riley  Steven T. Suess  Munetoshi Tokumaru  Brian T. Welsch  Thomas N. Woods 《Solar physics》2011,274(1-2):29-56

We present an overview of the data and models collected for the Whole Heliosphere Interval, an international campaign to study the three-dimensional solar?Cheliospheric?Cplanetary connected system near solar minimum. The data and models correspond to solar Carrington Rotation 2068 (20 March??C?16 April 2008) extending from below the solar photosphere, through interplanetary space, and down to Earth??s mesosphere. Nearly 200 people participated in aspects of WHI studies, analyzing and interpreting data from nearly 100 instruments and models in order to elucidate the physics of fundamental heliophysical processes. The solar and inner heliospheric data showed structure consistent with the declining phase of the solar cycle. A closely spaced cluster of low-latitude active regions was responsible for an increased level of magnetic activity, while a highly warped current sheet dominated heliospheric structure. The geospace data revealed an unusually high level of activity, driven primarily by the periodic impingement of high-speed streams. The WHI studies traced the solar activity and structure into the heliosphere and geospace, and provided new insight into the nature of the interconnected heliophysical system near solar minimum.  相似文献   

Limnology of Bird Pond,Ross Island,Antarctica     

Barbara Spurr 《新西兰海洋与淡水研究杂志》2013,47(4):547-562

The physical, chemical and biological properties of Bird Pond, Cape Bird, Ross Island, Antarctica (77° 13’ 10” S, 166° 28’ 30” E), were investigated at weekly intervals for 2 months in the summer of 1970–71. The above properties were also investigated over a 24‐h period. Salinity and temperature tolerance of the rotifer Philodina gregaria were investigated in the laboratory at Cape Bird.

Bird Pond is characterised by a high conductivity and chloride ion concentration, and an alkaline pH. It has a water temperature as high as 15°c in mid summer, with the bottom water temperature often 3°c higher than the surface temperature. Diurnal measurements suggest a vertical movement of phytoplankton during a 24‐h period. P. gregaria survives ionic concentrations up to 250 000 g.m^‐3 Na⁺ + Cl^‐, and water temperatures up to 32°c.  相似文献   

Complexities in hindcasting models--when should we say enough is enough     

Maslia ML  Aral MM  Faye RE  Grayman WM  Suárez-Soto RJ  Sautner JB  Anderson BA  Bove FJ  Ruckart PZ  Moore SM 《Ground water》2012,50(1):10-6; discussion 16-8

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The conservation of small water reservoirs in the Krajeńskie Lakeland (North-West Poland)     

Barbara Waldon 《Limnologica》2012,42(4):320-327

This study comprised an inventory of vascular plants in 450 small water reservoirs (up to 1 ha in size). Most water bodies (76%) in the study area (Krajeńskie Lakeland, NW, Poland) were located in an agricultural landscape, typical of the region. A total of 576 species of vascular plants were recorded. Of these, about 76% were native species, 34 taxa were listed as legally protected in Poland and endangered in the region (Western Pomerania) or in Poland. 201 plant communities were identified, including 128 associations.Depending on the surrounding habitat, the following groups of ponds were identified: (1) mid-forest ponds; (2) mid-wetland ponds; ponds between arable fields, including (3) water basins with wide, well developed ecotone zones and (4) ponds with narrow or disturbed contact zones; and (5) ponds in urban areas. 30 ponds of each type were compared in detail. Differentiation and plant species richness of small water reservoirs was dependent on landscape type. The richest ponds were located within fields but isolated from their surroundings by a natural belt of rushes or trees, whilst mid-forest ponds were the poorest. Valorization was based on the presence of valuable flora (e.g. native, rare, and endangered species) and plant communities. This revealed that mid-forest and mid-wetland ponds were the most natural, while ponds in urban areas were the most strongly transformed.Ponds in the study area (n = 450) were also analysed for anthropogenic impacts. Anthropogenic stressors were observed in 51% of ponds. The most serious threats to the ponds of the Krajeńskie Lakeland were deterioration due to drainage and eutrophication. Over 35% of ponds were connected to a network of drainage ditches, with the highest percentage (57.1%) found in mid-forest ponds type.  相似文献   

Abundance, diversity and succession of aquatic Coleoptera and Heteroptera in a cluster of artificial ponds in the North German Lowlands     

Armin Bloechl  Barbara Philippi  Albert Melber 《Limnologica》2010,40(3):215-188

Our study describes and evaluates environmental influences on assemblages of aquatic Coleoptera and Heteroptera in artificial ponds situated near Lake Steinhude in Lower Saxony (Germany). We determined temporal dynamics and colonization patterns for 14 ponds of different age. In total, we recorded 4941 individuals that represented 87 species of aquatic beetles and bugs. Between 30 and 40 species were found in most of the ponds. Heteropteran species of the families Corixidae and Notonectidae acted as pioneer species in new ponds, while aquatic coleopterans predominated in older ponds. The results of Canonical Correspondence Analyses (CCA) showed that among the key factors affecting community structure were land use, vegetation cover, water chemistry and the age of the ponds. We found that the distribution of adjacent ponds on areas with different land use has a positive influence on the diversity and abundance of the aquatic insect fauna.  相似文献   

Mixed Land Use and Obesity: An Empirical Comparison of Alternative Land Use Measures and Geographic Scales     

Ikuho Yamada  Barbara B. Brown  Ken R. Smith  Cathleen D. Zick  Lori Kowaleski-Jones  Jessie X. Fan 《The Professional geographer》2013,65(2):157-177

Obesity is a growing epidemic in the United States. Walkable neighborhoods, characterized as having the three Ds of walkability (population Density, land use Diversity, and pedestrian-friendly Design), have been identified as a potentially promising factor to prevent obesity for residents. Past studies examining the relationship between obesity and walkability vary in geographic scales of neighborhood definitions and methods of measuring the three Ds. To better understand potential influences of these sometimes arbitrary choices, we test how four types of alternative measures of land use diversity measured at three geographic scales relate to body mass index for 4,960 Salt Lake County adults. Generalized estimation equation models demonstrate that optimal diversity measures differed by gender and geographic scale and that integrating walkability measures at different scales improved the overall performance of models.  相似文献   

A land-use-based modelling chain to assess the impacts of Natural Water Retention Measures on Europe’s Green Infrastructure     

Sarah Mubareka  Christine Estreguil  Claudia Baranzelli  Carla Rocha Gomes  Carlo Lavalle  Barbara Hofer 《International journal of geographical information science》2013,27(9):1740-1763

This article details the process of integrating models to answer a specific policy-driven question: ‘What could be the impact of proposed Natural Water Retention Measures (NWRMs) on Europe’s Green Infrastructure (GI)?’ It describes the new Land Use Modelling Platform (LUMP), now enabling a high spatial scale (100-m) and large coverage (pan-European), whereby several sector-specific models contribute to assessing the impact of regional-level policy on a given spatial topic of concern. The configuration (land claims and land allocations modules) and calibration (accessibility and biophysical suitability) of the LUMP are explained. Four NWRM scenarios (riparian areas, afforestation, grassland and baseline scenario) are configured to run the simulations. For the reference: year 2006, the spatial representation of GI is based on land-use features of a refined version of the CORINE Land Cover (CLC), and resumed as connected components made of nodes and links.

Mathematical morphological image processing and network graph theory model, available from the free software package GUIDOS (the Joint Research Center of the European Commission), enabled the measurement of the GI connectivity and identified most critical links. Results show that the competition for land claimed by different economic sectors, combined with policy-driven rule-sets for the implementation of different NWRMs, yields very different results for the 2030 land-use projections, and subsequently for the morphology of GI. Three indicators associated with the morphology of GI are computed in order to assess the model outputs for 2030. The indicators are computed to answer the following questions: (1) How is the quantity of GI affected by each of the NWRM, and what proportion of that GI is most valuable? (2) What is the location of the most critical nodes and connectors of GI, and what land-use conversions occur under these? (3) Are the average components getting larger or smaller?

Whereas the grassland measure results in the largest net increase of GI, the afforestation measure results in the overall largest number of hectares of key nodes and links within the network. Land conversions occur under the critical GI nodes and links, with a large increase in agricultural areas, especially for the riparian measure under critical nodes and the grassland measure under critical links. Also predominant is the swapping of land from pasture to forest under critical links with the afforestation measure. The riparian measure most increases the average size of GI components, and all three measures contribute to bridging two large components which were divided in the 2006 land-use map, thus increasing the size of the largest component by more than 50%.  相似文献   

Shifts in isotopic signatures of animals with complex life-cycles can complicate conclusions on cross-boundary trophic links     

Maria Alp  Barbara L. Peckarsky  Stefano M. Bernasconi  Christopher T. Robinson 《Aquatic Sciences - Research Across Boundaries》2013,75(4):595-606

Stable isotopes (¹³C and ¹⁵N) are widely applied in studies of trophic links. We used this method to investigate the contribution of aquatic and terrestrial prey to the diet of riparian predatory arthropods in two mountain headwater streams in Colorado, USA. Aquatic and terrestrial prey and riparian predators were collected during summer 2009. To evaluate the reliability of conclusions based on stable isotope ratios, we compared the isotopic signatures of aquatic larval and terrestrial adult stages of three abundant stream insect species and assessed variation in mixing model estimates for spider diet composition under varying assumptions for trophic fractionation. Adult isotopic signatures of some aquatic prey species were indistinguishable from those of prey species with exclusively terrestrial life histories (stoneflies: ¹³C and ¹⁵N, chironomids: ¹³C). Other prey had distinctly aquatic isotopic signatures as both larvae and adults (a mayfly and a caddisfly). There was no evidence that prey with aquatic isotopic signatures contributed to the diet of the spiders near one stream. For the other stream, mixing model analysis suggested that chironomids were included in the diets of lycosid, linyphiid and liocranid spiders. Reliable estimates of the contributions of prey sources were compromised by the sensitivity of mixing models to assumptions on trophic fractionation and the presence of “isotopically cryptic” prey. This study emphasizes the importance of supporting isotope-based studies on cross-boundary trophic links with data on isotopic shifts in prey with complex life cycles and assessment of fractionation rates specific to the study system.  相似文献   

Environmental changes in southeastern Amazonia during the last 25,000 yr revealed from a paleoecological record     

Barbara Hermanowski  Marcondes Lima da Costa  Hermann Behling 《Quaternary Research》2012,77(1):138-148

New pollen, micro-charcoal, sediment and mineral analyses of a radiocarbon-dated sediment core from the Serra Sul dos Carajás (southeast Amazonia) indicate changes between drier and wetter climatic conditions during the past 25,000 yr, reflected by fire events, expansion of savanna vegetation and no-analog Amazonian forest communities. A cool and dry last glacial maximum (LGM) and late glacial were followed by a wet phase in the early Holocene lasting for ca. 1200 yr, when tropical forest occurred under stable humid conditions. Subsequently, an increasingly warm, seasonal climate established. The onset of seasonality falls within the early Holocene warm period, with possibly longer dry seasons from 10,200 to 3400 cal yr BP, and an explicitly drier phase from 9000 to 3700 cal yr BP. Modern conditions with shorter dry seasons became established after 3400 cal yr BP. Taken together with paleoenvironmental evidence from elsewhere in the Amazon Basin, the observed changes in late Pleistocene and Holocene vegetation in the Serra Sul dos Carajás likely reflect large-scale shifts in precipitation patterns driven by the latitudinal displacement of the Inter-Tropical Convergence Zone and changes in sea-surface temperatures in the tropical Atlantic.  相似文献