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981.
The Salí River hydrogeological basin is one of the most productive artesian basins in Argentina. It is located in the southeastern
part of the province of Tucumán, northwestern Argentina, and its groundwater resources are developed for water supply and
irrigation. The chemical composition of the water is strongly influenced by the interaction with the basinal sediments and
by hydrologic characteristics such as the flow pattern and time of residence.
Three hydrochemical zones are defined in the study area and the processes that control the chemical composition of the water
are manifestly different in each zone. The dissolution of halite, sodium sulphate, and gypsum explains part of the contained
Na+, K+, Cl–, SO4
2–, and Ca2+, but other processes, such as cation exchange, calcite precipitation, weathering of aluminosilicates, and gas exchange with
the atmosphere, also contribute to the water composition.
The assessment of contamination indicators, such as pH, dissolved organic matter, dissolved oxygen, phosphate, and nitrate,
indicates that the groundwater is suitable for human consumption. However, biological contamination has been detected in samples
from some wells, especially those near the Salí River.
Electronic Publication 相似文献
982.
Mushtak Talib Jabbar Faculty of Earth Resources China University of Geosciences Wuhan 《中国地质大学学报(英文版)》2001,12(2)
INTRODUCTIONLargeareasofaridandsemiaridregionsoftheworldareaf fectedbywinderosion .Approximately 2 8.4%ofthisareaareaffectedbysevereandveryseverewinderosion (Katesetal.,1977) .InIraq ,thearidandsemiaridregionsrepresentnearly 75%ofthetotalland .5 0 %ofthislandissubjec… 相似文献
983.
Sun Jinzhong College of Engineering Technology China University of Geosciences Beijing Tan Hanhua Guizhou Institute of Communication Design Guiyang Qi Shengwen Institute of Geology Chinese Academy of Sciences Beijing 《中国地质大学学报(英文版)》2001,12(2)
INTRODUCTIONBecauseofitssimpleoperationandlowcostaswellaseffec tivenessformanyprojects ,heavytampinghasbeenusedwidelyintheworld (Qianetal.,1986 ) .However,thestrongvibrationinsoilmasscausedbyheavytampingmaybeharmfultobuildings,instrumentsandevenhumanbodiesar… 相似文献
984.
Liu Qingsheng Department of Geophysics China University of Geosciences Wuhan The State Key Laboratory of Oil/Gas Reservoir Geology Exploitation of China Institute of Chengdu Technology Chengdu Wu Qifan Li Haixia Department o 《中国地质大学学报(英文版)》2001,12(2)
INTRODUCTIONThepresenceofmagneticanomaliesoveroilandgasfieldshasbeenknownforseveraldecades,butitisonlyinrecentyearsthatthephenomenonhasbeencriticallyinvestigated .Themag neticcharacteristicsofsoilandsedimentarecloselyrelatedtosomegeochemicalprocesses,s… 相似文献
985.
Agricultural practices, hydrology, and water quality of the 267-km2 Big Spring groundwater drainage basin in Clayton County, Iowa, have been monitored since 1981. Land use is agricultural; nitrate-nitrogen
(-N) and herbicides are the resulting contaminants in groundwater and surface water. Ordovician Galena Group carbonate rocks
comprise the main aquifer in the basin. Recharge to this karstic aquifer is by infiltration, augmented by sinkhole-captured
runoff. Groundwater is discharged at Big Spring, where quantity and quality of the discharge are monitored.
Monitoring has shown a threefold increase in groundwater nitrate-N concentrations from the 1960s to the early 1980s. The nitrate-N
discharged from the basin typically is equivalent to over one-third of the nitrogen fertilizer applied, with larger losses
during wetter years. Atrazine is present in groundwater all year; however, contaminant concentrations in the groundwater respond
directly to recharge events, and unique chemical signatures of infiltration versus runoff recharge are detectable in the discharge
from Big Spring.
Education and demonstration efforts have reduced nitrogen fertilizer application rates by one-third since 1981. Relating declines
in nitrate and pesticide concentrations to inputs of nitrogen fertilizer and pesticides at Big Spring is problematic. Annual
recharge has varied five-fold during monitoring, overshadowing any water-quality improvements resulting from incrementally
decreased inputs.
Electronic Publication 相似文献
986.
Impacts of afforestation on groundwater resources and quality 总被引:4,自引:0,他引:4
Plans to double the proportion of land under forest cover in Ireland by the year 2035 have been initiated. The plan, primarily
financially driven, ignores potential environmental impacts of forestry, particularly impacts on groundwater resources and
quality. Since groundwater supplies almost 25% of Ireland's total potable water, these impacts are important. Field investigations
indicate that afforestation leads to a reduction in runoff by as much as 20%, mainly due to interception of rainfall by forest
canopies. Clearfelling has the opposite impact. Implications are that uncoordinated forestry practices can potentially exacerbate
flooding. Groundwater recharge is affected by forestry, largely due to greater uptake of soil water by trees and to increased
water-holding capacity of forest soils, arising from higher organic contents. Recharge rates under forests can be reduced
to one tenth that under grass or heathland. Groundwater quality may be affected by enhanced acidification and nitrification
under forests, due partly to scavenging of atmospheric pollutants by forest canopies, and partly to greater deposition of
highly acid leaf litter. The slower recharge rates of groundwater under forests lead to significant delays in manifestation
of deterioration in groundwater quality.
Electronic Publication 相似文献
987.
Martin Gast Wolfgang Schaaf Joerg Scherzer Rudolf Wilden Bernd U. Schneider Reinhard F. Hüttl 《Journal of Geochemical Exploration》2001,73(2):196
To analyze the development of pine ecosystems on lignite and pyrite containing mine soils, four pine stands with ages of 3–35 years were investigated in a chronosequence approach. Bulk precipitation, throughfall and soil solution in depths of 20, 40, 70 and 100 cm were studied over a three-year period to determine element fluxes in these forest ecosystems on extreme acidic and saline soils.Element budgets are controlled by the processes induced by pyrite oxidation such as intensive weathering of primary minerals, precipitation and leaching of secondary phases.Despite low water fluxes, element outputs can reach extraordinary high values due to very high concentrations in the soil solution. Although element outputs decrease drastically with stand age, respectively, site age, they exceed those of comparable pine stands on non-mine sites. Nitrogen release from the lignite fraction represents a special characteristic of the examined substrates. Nitrogen losses beneath the rooted zone can be 34 kg N ha−1 yr−1 in 100 cm depth. Element input and output in the examined ecosystems are far from balance. Closed cycling of nutrients seems to be recognizable in the case of potassium. 相似文献
988.
Brenda S. Pierce Artur Martirosyan Gourgen Malkhasian Samvel Harutunian Grigory Harutunian 《International Journal of Coal Geology》2001,45(4):307
The Antaramut–Kurtan–Dzoragukh (AKD) coal deposit is a previously unrecognized coal field in north-central Armenia. Coal has been known to exist in the general vicinity since the turn of the century, but coal was thought to be restricted to a small (1 km2) area only near the village of Antaramut. However, through detailed field work and exploratory drilling, this coal deposit has been expanded to at least 20 km2, and thus renamed the Antaramut–Kurtan–Dzoragukh coal field, for the three villages that the coal field encompasses. The entire coal-bearing horizon, a series of tuffaceous sandstones, siltstones, and claystones, is approximately 50 m thick. The AKD coal field contains two coal beds, each greater than 1 m thick, and numerous small rider beds, with a total resource of approximately 31,000,000 metric tonnes. The coals are late Eocene in age, high volatile bituminous in rank, relatively high in ash yield (approximately 40%, as-determined basis) and moderate in sulfur content (approximately 3%, as-determined basis). The two coal beds (No. 1 and No. 2), on a moist, mineral-matter-free basis, have high calorific values of 32.6 MJ/kg (7796 cal/g) and 36.0 MJ/kg (8599 cal/g), respectively. Coal is one of the few indigenous fossil fuel resources occurring in Armenia and thus, the AKD coal field could potentially provide fuel for heating and possibly energy generation in the Armenian energy budget. 相似文献
989.
990.
本文主要介绍利用佛山市航空遥感综合调查资料分析城市环境的空间结构,建立了空间结构分类系统,探讨了城市形态的变化,综合评价城市空间环境质量,并提出一些改善环境质量的建议. 相似文献