Honda saline lake is located in an endorheic basin in the south of Spain. The lake is very shallow, with frequent seasonal
drought and a high degree of unpredictability. It was sampled monthly during a relatively dry year (1994–1995, 5 months permanence).
To establish a relationship between environmental variables (temperature, depth, salinity and conductivity), variables related
to biological activity (organic matter, total solids suspension, and pH) and the planktonic community in the sampled months,
various uni-and miltivariate statistical methods were carried out.Dunaliella salina, D. viridis, and ciliates sp. 2 is the principal species group used to average out the dissimilarity between the samples. Muttivariate
analysis showed that salinity (as TDS), conductivity and pH made major and significant contributions to the explanation of
the variance in the sample data. 相似文献
Concentrations of Pb and Zn, plant uptake of these metals, the influence of the plants’ growth on the physicochemical properties and metal concentrations in the tailings of an abandoned 300-year-old mine tailing dam in Zacatecas, Mexico were investigated. Tailings were found to be heavily contaminated, with average levels of 2621 ± 53 and 3827 ± 83 mg/kg for Pb and Zn, respectively (maximum concentrations of 8466 ± 116 and 12,475 ± 324 mg/kg, respectively), exceeding international standards. Though physico-chemical conditions (pH, conductivity, redox potential, moisture, organic matter, nitrate, nitrite, ammonium nitrogen, total nitrogen, phosphorus and sulfates) do not favor the development of vegetation, some plants have adapted to these adverse conditions. Moreover, there was a significant reduction of Pb and Zn concentration in the rhizosphere (between 10–78% for Pb and 18–62% for Zn, depending on plant species). Sporobolus airoides showed average biomass concentrations of 173 ± 2 and 313 ± 6 mg/kg, for Pb and Zn, respectively; which implies a risk for mobility and possible incorporation into the food chain. Barcleyanthus salicifolius, Asclepsias linaria and Cortaderia selloana on the other hand, showed average biomass concentrations of 28 ± 3 and 121 ± 5 mg/kg of Pb and Zn, respectively, thus representing a lower biomagnification risk. The effect of these plants to reduce metal concentrations in the rhizosphere, improve physico-chemical conditions in metal polluted substrates, but with limited metal accumulation in biomass, suggests that they can be evaluated for use in stabilizing metal polluted tailings. 相似文献
Agriculture practices have been widely proposed as the major cause of amphibian population decline. However, the majority of these results have been based on laboratory experiments. The present study was conducted to test the repercussion of wetland sediment provenance on amphibian larval development. Bufo bufo larvae were used in two different treatments in an outdoor experiment, the first one using sediment from one wetland surrounded by intensive agricultural practices, and the second using sediment with no record of agrochemical uses. A negative effect was observed in the agricultural treatment, from subcellular to individual level. The results showed that the sediment from agricultural practices watershed generates a reduction in survival. Furthermore, individuals that developed under this treatment showed a lower total length and a delay in the time necessary to complete metamorphosis; these features are connected with recruitment success. In the same way, biochemical analysis showed high values of lipid peroxidation in metamorphs developing in sediments from an agricultural area. Finally, the results obtained highlight the importance of considering the sediments, not only the water, as origin treatment, allowing us to understand the consequences on amphibian populations that inhabit areas affected by intensive agriculture.
The springtime temporal variations of striped weakfish (Cynoscion guatucupa) population structure available to the commercial fishery and its relationship to environmental factors were evaluated in the Uruguayan coastal zone (35° −33.4°S), from 86 stations sampled in 1994, 98, 99 and 2003. We examined the inter-annual variability of age-class structure over four years under different oceanographic conditions: (1) 1998 (El Niño year) was characterized by elevated water temperature; (2) 1999 (La Niña year) was characterized by decreased water temperature; and (3) 1994 and 2003 were ‘typical years’ with intermediate values in those parameters. To determine whether or not major shifts in population structure occurred between years we used ANOSIM and SIMPER analysis to determine which age-class typified and discriminated between years. A canonical correspondence analysis (CCA) was used to define the temporal pattern of age-class structure of C. guatucupa and to estimate its associations with environmental factors (depth, temperature, salinity, vertical stratification, and zonal and meridional component of the wind). The C. guatucupa population structure showed significant difference between 1998 and 1999 and 1994–2003. During 1998 and 1999, the population structure was dominated by adults (between 4 and >7 age-class), while that in 1994 and 2003 was dominated by juveniles (between 0 and 3 age-class). CCA results indicated that zonal wind and salinity has a major influence on the temporal pattern of C. guatucupa population structure. Juvenile population structure was associated with low salinities and occurred when the wind field forced an inflow of freshwater into the marine coastal area from the Rio de la Plata estuary, while the adult structure, associated with high salinities, occurred when the area was dominated by a wind driven inflow of higher salinity shelf water. These results support the hypothesis that the short-term environmental synoptic condition has a greater influence on the distribution and population structure of C. guatucupa than long-term environmental variability. 相似文献
Currently, aquifers are considered to be ecosystems that interchange materials and energy with other systems located in their surroundings. The aquifer system of Doñana (southwest Spain) has been studied over recent decades from a hydrogeological point of view, although nothing is known about its biological or ecological aspects. In order to describe the general characteristics of its microbial communities, bacterial abundance, cell biomass, bacterial biomass and microbial activities of functional groups were investigated by sampling, over a 2-year period, 13 wells located in the vicinity of four very productive shallow lakes in the most superficial part of this coastal, sandy aquifer system. Multivariate analysis of variance (MANOVA) indicated differences in abundance and biomass variables among sampling locations, seasons and sampling locations × seasons. Principal component analysis showed that temperature and dissolved oxygen appeared to be the most important factors controlling the temporal variability of microbial communities. Hydrological connectivity between surface water and groundwater was important in the control of the spatiotemporal distribution of microbial communities. Due to this hydrological connection, the aquifer system and the wetlands constitute a unique entity, a unique ecosystem, called the “hydroecosystem”, where microbial communities could play a central ecological role. 相似文献
Pb–Zn deposits are widespread and common in various parts of the Taurus Belt. Most of the deposits are of pyrometasomatic and hydrothermal origin. The Keban Pb–Zn deposits are located along the intrusive contact between the Paleozoic – Lower Triassic Keban Metamorphic Formation and the syenite porphyry of the Upper Cretaceous Keban igneous rocks. Various studies have already been carried out; using fluid inclusion studies on fluorite, calcite and quartz on the pyrite–chalcopyrite bearing Keban ore deposits. This study focuses on the interpretation of stable isotope compositions in connexion with fluid inclusion data. Sulphur isotope values (δ34S) of pyrite are within the range of ?0.59 to +0.17‰V-CDT (n = 10). Thus, the source of sulphur is considered to be magmatic, as evidenced by associated igneous rocks and δ34S values around zero“0”. Oxygen isotope values δ18O of quartz vary between +10.5 and +19.9‰(SMOW). However, δ18O and δ13C values of calcite related to re-crystallized limestone (Keban Metamorphic Formation) reach up to +27.3‰(SMOW) and +1.6‰(PDB), respectively. The δ34S, δ13C and δ18O values demonstrate that skarn-type Pb–Zn deposits formed within syeno-monzonitic rocks and calc-schist contacts could have developed at low temperatures, by mixing metamorphic and meteoric waters in the final stages of magmatism. 相似文献
The production of a cartographic landslide inventory in the glaciated headwaters of the upper Gállego River, Axial Zone of the Spanish Pyrenees, revealed several paleolakes. These relict lake basins are related to the blockage of drainages by postglacial earthflows and slides, mainly developed on Paleozoic slates. The paleolakes are recorded either by non-dissected infilled basins or by hanging and incised lacustrine terraces that persisted for thousands of years. The development of lakes upstream of landslides, was favored, despite their erodibility, by high-displacement rates and the occurrence of paired landslides on both sides of the valley. Radiocarbon and single-grain optically stimulated luminescence (OSL) ages obtained on the lake sediments range between 41.5?±?3.9 ka and 15.1?±?0.3 ka. These chronologies indicate prolonged landslide activity long after the early deglaciation in the upper Gállego River Valley. The landslide-lake dating results support the interpretation that the regional maximum ice extent (MIE) in the Pyrenees occurred during the marine isotope stage 4 (MIS 4), long before the global Last Glacial Maximum (LGM). 相似文献