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1.
The effluent contamination of groundwater at two industrial sites at Visakhapatnam, India, was studied using factor analysis.
Thirty groundwater samples near a zinc smelter plant and 19 from the polymers plant were analyzed for specific conductance,
chloride, bicarbonate, sulfate, calcium, magnesium, sodium, and potassium. The data were subjected to R-mode factor analysis
and the factor scores transferred to areal maps. While magnesium and sulfate are the dominant contaminants at the zinc site,
sodium, chloride, and bicarbonate from the effluent are affecting groundwater in the polymers area. Contour maps for each
factor suggest the areal extension of the contaminants.
Received: 1 March 1995 · Accepted: 18 September 1995 相似文献
2.
贵阳永温中学岩溶塌陷发育临界条件研究 总被引:1,自引:1,他引:0
通过现场调查,永温中学校区内及周围存在7处塌陷点,1处塌陷隐患点,严重地威胁着该校师生生命财产安全。研究区基岩可溶性成分多,覆盖粘土层较薄,且地下水溶蚀性强,属于岩溶塌陷的高危险区。为了预防岩溶塌陷灾害,文章总结分析了研究区岩溶塌陷发育的裂隙-渗流-崩解模式,并通过室内模拟试验验证。模拟试验结果表明,土体含水量是崩解作用形成塌陷的关键参数。进一步开展8组不同含水量原状样的崩解试验,结果表明,研究区岩溶塌陷发育的土体含临界水量为26.8%,发育条件为0~26.8%。 相似文献
3.
《Applied Geochemistry》1997,12(3):321-325
Hammarsdale, an industrial centre about 40 km inland from the coastal city of Durban, South Africa experiences effluent treatment problems typical of highly industrialised centres. The majority of the factories in the area manufacture textiles, with the remainder comprising chemical manufacturers and a large chicken processing plant. Effluent produced by these industries constitutes approximately 97% of the flow to the local wastewater treatment works. This is operated by Umgeni Water, a regional water supply authority which has an interest in pollution control as part of its integrated catchment management strategy. The activated sludge treatment process employed at the works produces a sludge which, following dewatering, is transported to a nearby land disposal site which has been engineered to ensure environmentally acceptable use is made of the site. The heavy metal concentrations of the sludges produced by the Hammarsdale Wastewater Works have long been a matter of concern, in particular the elevated concentrations of Hg. Investigations of the land disposal site showed that the Hg is bound in the upper topsoil (0–10 cm), and only very low concentrations are found in the subsoil. As the soils at the disposal site possess low cation exchange capacities, the difference between Hg concentrations in the top and subsoils may be attributed to binding of the Hg by organic matter introduced by sludge addition. Current research on the disposal area is focused on the movement of Hg, N and other elements through the soil profile into plants, surface and groundwater resources, with the ultimate aim of identifying suitable crops for cultivation at the site following its use as a sludge disposal facility. 相似文献
4.
D. M. Kargbo 《Environmental Geology》1994,23(2):105-113
About 70 percent of hazardous waste sites listed in the National Priority List (NPL) have some groundwater contamination that may require remediation. Such remediation is inadequate if the unsaturated soils above will continue to act as a source of groundwater contamination. Consequently, for most of these sites, it becomes necessary to determine what the cleanup levels for contaminants in soils should be so that subsequent contribution of contaminants from these soils to groundwater would not exceed groundwater protection levels. Representation of the dynamics of interactions between contaminants and soils is very complex, requiring among others, a thorough understanding of the chemical processes that influence the behavior of the contaminant once it enters the subsurface. Because of such complexities, environmental professionals frequently utilize methods with very simple assumptions that tend to err on the conservative side. While the public may feel protected, the needless spending of dollars could be avoided if attempts are made to incorporate, where possible, such complexities in the modeling efforts so that the system is represented as accurately as possible. 相似文献
5.
Geochemical Atlas of Slovakia and examples of its applications to environmental problems 总被引:2,自引:0,他引:2
S. Rapant D. Bodiš K. Vrana V. Cvečková J. Kordík K. Krčmová I. Slaninka 《Environmental Geology》2009,57(1):99-110
Results of comprehensive geochemical mapping and thematic studies of the Slovak territory (rocks, soils, stream sediments,
groundwaters, biomass, and radioactivity) in the first half of the 1990s led to several new research programmes in Slovakia,
within the frame of which new methodologies for geochemical data evaluation and map visualization were elaborated. This study
describes the application and elaboration of data from the Geochemical Atlas of the Slovak Republic at national and regional
levels. Based on the index of environmental risk (IER = ΣPEC/PNEC), the level of contamination for the geological component of the environment in Slovakia was evaluated. Approximately
10.5% of Slovakia’s territory was characterized as being environmentally disturbed to highly disturbed. In the areas where
environmental loadings have accumulated, 14 regions where environmental risks existed due to high element concentrations were
defined. The model calculations of health risk estimates based on the databases of the Geochemical Atlas for groundwater and
soils indicate that the possible risk occurrence of carcinogenic diseases from groundwater arsenic contents is high in more
than 10% of Slovakia, whereas the chronic risk is negligible. To determinate the background and threshold levels a combined
statistical–geochemical approach was developed and applied as an example for groundwater at the national level as well as
for single groundwater bodies. The results of statistical method application for the whole groundwater body (GBW) were compared
with the background values for anthropogenically non-influenced areas in GBW. Final background value took into account time
variations and spatial distribution of the element in GBW. Furthermore, based on the database from the Geochemical Atlas for
groundwater, groundwater bodies potentially at qualitative risk were delineated for the whole of Slovakia. From a total of
101 groundwater bodies 17 were characterized as being at risk and 22 as being at possible risk. 相似文献
6.
Geochemical and hydrologic controls on the mobilization of arsenic derived from herbicide application 总被引:1,自引:0,他引:1
Arthur G. Fitzmaurice A. Azra Bilgin Peggy A. ODay Virginia Illera David R. Burris H. James Reisinger Janet G. Hering 《Applied Geochemistry》2009,24(11):2152-2162
The fate and transport of As was examined at an industrial site where soil- and groundwater contamination are derived from the application of As2O3 as a herbicide. Application of arsenical herbicides was discontinued in the 1970s and soils in the source area were partially excavated in 2003. Arsenic contamination (up to 280 mg/kg) remains in the source area soils and a plume of As-contaminated groundwater persists in the surficial aquifer downgradient of the source area with maximum observed As concentrations of 1200 μg/L near the source area. The spatial extent of As contamination as defined by the 10 μg/L contour appears to have remained relatively stable over the period 1996–2006; the boundary of the 1000 μg/L contour has retreated over the same time period indicating a decrease in total As mass in the surficial groundwater.In column experiments conducted with source area soil, the As concentrations in the column effluent were comparable to those observed in groundwater near the source area. A substantial fraction of the As could be leached from the source area soil with ammonium sulfate and ammonium phosphate. Exhaustive extraction with background groundwater removed most of the total As. These results indicate that As in the source area soils is geochemically labile. Source area soils are low in extractable Fe, Mn and Al, and characterization by X-ray absorption spectroscopy and electron microscopy indicated that As is present primarily as arsenate sorbed to (alumino)silicate minerals. Batch sorption experiments showed much less sorption on surficial aquifer sediments than on sediments from the Jackson Bluff Formation (JBF), a presumed confining layer. This limited capacity of the surficial aquifer sediments for As sorption is consistent with the similar As contents observed for these sediments within and upgradient of the As plume. The apparent stability of the As plume cannot be explained by sequestration of As within the surficial aquifer. Sorption to JBF sediments may contribute to As sequestration, but As enrichment in JBF sediments within the plume (i.e., as compared with JBF sediments upgradient) was not observed. These results indicate that neither the persistence of As in the source area soils or the apparent stability of the plume of As-contaminated groundwater at this site can be explained by geochemical controls on As mobility. The absence of demonstrable geochemical bases for such observations suggests that possible hydrologic controls should be further investigated at this site. 相似文献
7.
Mahmoud S. Alyamani 《GeoJournal》1999,48(4):291-297
In Wadi Tharad the groundwater has been subjected to hydrochemical study to identify the process (s) that led to the formation
of relatively highly saline water in shallow alluvial aquifer. The chemical analyses results show that the groundwater salinity
was highly variable and randomly distributed along the wadi course. This variation could be attributed to intensive evaporation
on effluent prone surface irrigation water that led to precipitation of evaporates (e.g., calcite, dolomite, gypsum and probably
halite). The intensive irrigation practice through mineral dissolution recharged the groundwater with a marked increase in
the salinity. The local hydrogeological condition is also involved in determining the risk of the groundwater salinity as
a consequence of irrigation practice.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
8.
The Ganga Plain is one of the most densely populated regions and one of the largest groundwater repositories of the Earth.
For several decades, the drainage basin of the Ganga Plain has been used for the disposal of domestic and industrial wastes
which has adversely affected the quality of water, sediments and agricultural soils of the plain. The concentrations of Al,
Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Zn and organic carbon were determined in river sediments and soils of the Ganga Plain
in the Kanpur-Unnao industrial region in 1994 and 1995 (pre-monsoon period of April–May). High contents (maximum values) of
C-org (12.0 wt. %), Cr (3.40 wt. %), Sn (1.92 wt. %), Zn (4000 mg/kg), Pb (646 mg/kg), Cu (408 mg/kg), Ni (502 mg/kg) and
Cd (9.8 mg/kg) in sediments (<20 μm fraction); and C-org (5.9 wt. %), Cr (2.16 wt. %), Sn (1.21 wt %), Zn (975 mg/kg) and
Ni (482 mg/kg) in soils (<20 μm) in the pre-monsoon period of 1994 were found. From 1994 to 1995 the contents of Fe and Sn
in sediments increase whereas those of C-org, Cd, Cu, Ni and Zn decrease. Considering the analytical errors, Al, Co, Cr, Mn
and Pb do not show any change in their concentrations. In soils, the contents of Cd, Fe and Sn increase whereas those of Ni
decrease from 1994 to 1995. Aluminium, Co, Cr, Cu, Mn, Pb and Zn do not show any change in their concentrations from 1994
to 1995. About 90% of the contents of Cd, Cr and Sn; 50–75% of C-org, Cu and Zn; and 25% of Co, Ni and Pb in sediments are
derived from the anthropogenic input in relation to the natural background values, whereas in soils this is the case for about
90% of Cr and Sn; about 75% of Cd; and about 25% of C-org, Cu, Ni and Zn. The sediments of the study area show enrichment
factors of 23.6 for Cr, 14.7 for Cd, 12.2 for Sn, 3.6 for C-org, 3.2 for Zn, 2.6 for Cu and 1.6 for Ni. The soils are enriched
with factors of 10.7 for Cr, 9.0 for Sn, 3.6 for Cd, 1.8 for Ni and 1.5 for Cu and Zn, respectively.
Received: 3 March 1998 · Accepted: 15 June 1998 相似文献
9.
Analysis of remedial alternatives of the Nanji Landfill,Korea 总被引:1,自引:0,他引:1
Jeonsang Hahn 《Environmental Geology》1996,28(1):12-21
This paper presents an analysis of various remedial alternatives for a representative waste disposal site causing serious
adverse affects to the surrounding soil and surface and groundwater systems and discusses the application of this approach
in a case study. The numerical flow model along with the transport model in three dimensions were utilized to simulate current
flow conditions at the site and its vicinity for calibration and to provide the analysis results for various remedial alternatives,
such as top capping, vertical barrier, extraction, and hydrodynamic control. While the development of remedial alternatives
and the selection of the most effective remedial measures are highly site-specific, the approach and methodology presented
in this paper have general applicability. The conditions outlined in this study are used by environmental engineers and planners
who incorporated economic and engineering decisions and public acceptance for various remedial measures considered; they also
provide insight into the difficulties and special considerations associated with modeling and analyzing remedial alternatives.
Received: 19 September 1995 · Accepted: 6 November 1995 相似文献
10.
地下水污染场地风险管理与修复技术筛选 总被引:4,自引:0,他引:4
赵勇胜 《吉林大学学报(地球科学版)》2012,42(5):1426-1433
国际上对于地下水污染场地的控制与修复研究已经取得了许多成果,已有成功的修复实例。我国虽然起步晚,但非常重视地下水污染的防治,开展了全国范围的地下水污染调查,并进行了地下水污染的防治规划。地下水污染的控制与修复已经逐渐进入示范性研究阶段。面对地下水污染场地风险管理的不同方法,以及众多的污染修复技术,如何制定风险管理策略,如何在各种各样的修复技术中筛选合适的技术或技术组合,对于地下水污染场地的防治具有非常重要的意义。笔者分析了发达国家地下水污染风险管理策略,结合在地下水污染场地研究方面的经验,对一些主要的地下水污染修复技术进行了分析论述,提出了考虑污染物特征、场地水文地质条件的地下水污染修复技术的筛选过程和方法。 相似文献
11.
南京城市土壤某些元素的富集特征及其对浅层地下水的影响 总被引:20,自引:2,他引:20
本研究以南京市的公园、校园绿地、道路绿地和郊区菜地等不同功能区的土壤为对象,对土壤的磷素和重金属以及一些土壤剖面点位的地下水组成进行了分析.研究发现城市土壤构成了区别于自然背景的某些元素(如磷和重金属)的地球化学垒,形成了明显的元素富集区域,其中磷素含量是背景土壤的数倍甚至十数倍,Pb含量也远高出背景土壤,60%以上样品达到中等污染程度以上.从磷素在剖面中的积累模式可以看出,城市土壤中磷含量最高的层次出现在表层以下的不同深度,说明土壤经历了不同的扰动过程,这意味着在城市发展过程中,土壤的性质遭受强烈的人为活动影响,元素在土壤中的分布形态可以指示不同的利用历史.质量改变后的土壤对地下水等环境产生影响,使地下水的组成发生改变,其中磷素含量直接受到土壤的影响,效区菜地地下水中硝态氮含量极高,而本研究尚未发现地下水中的重金属含量与土壤有显著相关. 相似文献
12.
S. J. Appleyard 《Environmental Geology》1996,28(2):106-110
Drilling of 15 boreholes at a disused liquid waste disposal site near Perth, Western Australia, has indicated that a contamination
plume extends about 1000 m in a southerly direction from the site in the direction of groundwater flow. The plume is up to
600 m wide and 5–40 m thick. Chemical and microbiological analyses have indicated that contaminated groundwater contains high
concentrations of ammonia, iron, and bacteria at levels that commonly exceed national drinking water guidelines. It is likely
that a proposed water supply production well in the path of the contamination plume will have to be abandoned, and additional
wells may have to be abandoned if the plume continues to extend in the direction of groundwater flow. There is currently insufficient
information to indicate whether the plume is continuing to expand, but studies on similar plumes in the Perth metropolitan
area have indicated that contaminated groundwater can move at rates up to 100 m yr–1. Several other liquid waste disposal sites are now located in residential areas of Perth where wells are used for garden
irrigation. Further work is required to ensure that there is no potential impact of groundwater contamination on public health
in these areas.
Received: 31 July 1995 · Accepted: 18 September 1995 相似文献
13.
Groundwater availability in the shallow aquifers of the southern voltaian system: a simulation and chemical analysis 总被引:1,自引:0,他引:1
A steady state groundwater flow simulation model was developed using available well data and general hydrogeological and geological
information, for the Afram Plains area, Ghana. The hydrochemistry of groundwater from wells in the area was then evaluated
to determine its suitability for irrigation and domestic uses. The assessment of the irrigation quality of groundwater from
this area was based on salinity (EC) and sodium adsorption ratios (SAR), residual sodium carbonate (RSC), and permeability
indices (PI). The simulation model reveals that groundwater in the Afram Plains area generally flows from the midsections
in the neighborhood of Tease and surrounding areas, where significant recharge takes place, to the outer regions and discharges
into the Volta Lake in the southern and eastern sections of the area. Flow magnitude and piezometric maps suggest that there
is probably of less potential for groundwater extraction for sustainable irrigation in the central regions of the area, when
compared to the other discharge areas. This study reveals that more than 70% of the samples analyzed fall within the C2–S1
category, referring to the medium level salinity and low sodium. Medium salinity waters may be used for irrigation on coarse
textured soils with good permeability. About 15% of the data fall within the C3–S2 category, referring to water of high salinity
and medium sodicity. High salinity, medium sodicity irrigation water cannot be used on fine-grained soils where drainage is
restricted. This is because restricted flow is likely to result in the accumulation of salts in the root zones of crops, leading
to salinity and soil clogging crisis. About 3% falls within the C3–S3 (high salinity, high sodicity) category. This category
requires special soil management including improved drainage, heavy leaching and the use of chemical amendments on the water.
Only one point plots within the extreme salinity–sodicity range. Concentrations of fluoride, arsenic and other natural elements
in the area generally fall well within the world health standards for domestic water. 相似文献
14.
Mohsen Jalali 《Environmental Geology》2009,57(5):1011-1020
In areas of intensive crop production, continual phosphorous (P) applications as P fertilizer and farmyard manure have been
made at levels exceeding crop requirement. As a result, surface soil accumulations of P have occurred to such an extent that
loss of P in surface runoff and a high risk for P transfer into groundwater in concentrations exceeding the groundwater quality
standard has become a priority management concern. Phosphorous content of groundwater was determined in order to examine dissolved
P concentration and species in the groundwater and mineral solubilitiy in a semi-arid region of southern Malayer, western
Iran. The speciation for P in groundwater was calculated using geochemical speciation model PHREEQC. The concentration of
total P in the groundwater (0.01–2.56 mg P l−1) and estimated concentrations of HPO4
2− (49.5–89%), H2PO4
− (1.5–17.3%), CaHPO4
+ (5.7–36.1%), and CaPO4
− (1.4–12.2%) varied considerably amongst the groundwater. Results suggest that the concentration of P in the groundwater could
be primarily controlled by the solubility of octacalcium phosphate and β-tricalcium phosphate. Large amounts of P fertilizer,
inadequate management of P fertilization, and low irrigation efficiency, coupled with sandy soils in some parts of the study
area could be mainly responsible for the greater P in the groundwater. In general, the greater the dissolved P concentration
in the groundwater, the closer the solution was to equilibrium with respect to the more soluble Ca-phosphate minerals. The
groundwater P content could be potentially used to identify areas where management approaches, such as P applied and crop
type planted, could be adjusted to different types of soils, geology and topography. 相似文献
15.
E. M. Frempong 《Environmental Geology》1999,37(3):255-260
An engineering geological investigation has been undertaken of a proposed landfill site in coastal southwestern Ghana which
is characterized by torrential rains, high relative humidity, shallow groundwater conditions and almost surrounded by a ridge.
The study shows that the site has some desirable characteristics such as availability of suitable soils for the construction
of the capping and bottom liners of the landfill, a large tract of land for landfilling operation and its location close to
a major highway. However, the groundwater table was shallow and there was a high potential for leachate intrusion into and
consequent contamination of nearby groundwater abstraction wells and surface potable water sources thereby constituting serious
threat to life. Construction costs could be prohibitive as extensive dewatering and backfilling of vast portions of the project
site would be required to enable the provision of a separation between the shallow water table and the bottom of the landfill.
Received: 20 January 1998 · Accepted: 26 May 1998 相似文献
16.
Deterioration of groundwater quality in the vicinity of an active open-tipping site in West Malaysia 总被引:3,自引:0,他引:3
Bahaa-eldin E. A. Rahim I. Yusoff A. R. Samsudin W. Z. W. Yaacob A. G. M. Rafek 《Hydrogeology Journal》2010,18(4):997-1006
There is an urgent need for characterization of leachate arising from waste disposal to ensure a corresponding effective leachate management policy. Field and laboratory studies have been carried out to investigate the impact of municipal landfill leachate on the underlying groundwater at a site in West Malaysia. The solid waste was disposed of directly onto an unprotected natural soil formation. This situation was made worse by the shallow water table. The hydrochemical composition of groundwater in the vicinity of the site (background) is a dilute mixed cation, bicarbonate water. The high ionic balance error of ~13.5% reveals that the groundwater body underneath the site was a highly contaminated leachate rather than contaminated groundwater. Elevated concentration of chloride (355.48 mg/L), nitrate (10.40 mg/L as NO3), nitrite (14.59 mg/L), ammoniacal-N (11.61 mg/L), sodium (227.56 mg/L), iron (0.97 mg/L), and lead (0.32 mg/L) measured downgradient indicate that the contamination plume has migrated further away from the site. In most cases, the concentration of these contamination indicators, together with the ranges of sodium percentage (66.3–89.9%) and sodium adsorption ratio (10.1–19.7%), were found to be considerably higher than the limit values of safe water for both domestic and irrigation purposes, respectively. 相似文献
17.
K. Urushibara-Yoshino 《Environmental Geology》1996,28(3):154-160
The properties of soils on previously dated sand dunes from Robe to Naracoorte in South Australia were examined. In these
areas younger sand dunes are composed of fresh sand, but older sand dunes are composed of calcarenited sand. The soils on
the sand dunes developed successionally by the age of sand dunes. The soil properties of these sand dunes differ depending
on the ages of the sand dunes. The properties of sand particles in soils are as follows:
(1) On the sand dunes of 4300 years B.P., A/C profile developed (Rendzina). On the sand dunes older than 125 000 years B.P.
and on the plateau of Tertiary limestone, soil profiles of A1/AB/B/C on the sand dunes of 83 000 years B.P. and A1/A3/B1/B2/C (Terra rossa) are well developed.
(2) Within the sand of A/C horizons of the sand dunes with the age of 4300 year B.P., the calcite grain content is about 64%,
and the quartz content is about 35%. Within the B horizons of soils on the dunes from 83 000 years B.P. to 347 000 years B.P.,
the calcite grain content is only 1–2%; however, the quartz grain content is about 92%. In the B2 horizons of soils on the dune of 690 000 years B.P. and on the Tertiary plateau, there are some calcite grains but the quartz
grain content is about 96%.
(3) The average size of quartz grains in the soils on the sand dunes from 4300 B.P. to 347 000 years B.P. is generally smaller,
but the average size of quartz on the sand dunes of 690 000 year B.P. becomes larger and the grains are well rounded. On the
Tertiary limestone plateau, the average quartz size becomes again smaller, and the grains are more rounded.
(4) Fet in B2 horizon of the soil profiles increases clearly corresponding to the age. Iron activity expressed by Feo/Fed also shows a close relation to the chronological sequence. The B horizon of the soil profiles shows a drastic decrease of
Feo/Fed according to the age. Iron crystalinity, (Fed-Feo)/Fet, has a tendency for a positive relation with increasing age.
Received: 1 June 1995 · Accepted: 4 December 1995 相似文献
18.
D. Drew 《Environmental Geology》1996,27(2):97-98
Lisdoonvarna is a small town with a resident population of ca. 700, which is seasonally increased several-fold by tourists. It is located in the northwest of County Clare, western Ireland about 10 km from the Atlantic seaboard and adjacent to the karstic Burren plateau. Lisdoonvarna has two claims to fame: it is the only currently operative spa in Ireland, and it is the center for a long-established match-making festival held each September (postharvest) at which bachelor farmers are found partners by skilled match-makers. These two features of Lisdoonvarna are not wholly unconnected even though the September festival now attracts many young people from outside of the area who may not patronize the spa waters. 相似文献
19.
Hypothesis testing of buoyant plume migration using a highly parameterized variable-density groundwater model at a site in Florida, USA 总被引:1,自引:1,他引:0
Alyssa M. Dausman John Doherty Christian D. Langevin Joann Dixon 《Hydrogeology Journal》2010,18(1):147-160
A highly parameterized variable-density groundwater flow and solute transport model was developed to test multiple hypotheses for upward movement of treated wastewater (effluent) injected into a saline coastal aquifer in southeastern Florida, USA. The model was designed to assess risk to a drinking-water aquifer above the zone of injection, where monitoring wells have detected effluent. The model-based analysis accommodated geological and data complexity, including the observed presence of effluent in upper monitoring wells, but not in lower monitoring wells, thereby giving the appearance of the effluent having bypassed geological layers. The modeling approach included the application of multiple methodologies to reduce model run times during parameter estimation while providing detailed calibrated model(s) that can be used to assess the potential capacity for different mechanisms of effluent migration. The methods included use of a semi-analytical equation to quickly calculate initial concentrations, parallelization of model runs over multiple processors when calibrating, and utilization of the concepts of singular value decomposition and Tikhonov regularization to accommodate a high level of parameterization complexity. The results reveal that vertical effluent migration could occur as diffuse flow through heterogeneous confining units; however, flow through a channelized pathway caused by well construction appears to be more likely. 相似文献
20.
Ireland has large water resources. Only 5.3% of developable waters are as yet developed, to supply some 650 I/day/per capita to the population of some 3.37 million people. State of development varies in each of the seven water resources regions. Precipitation is fairly evenly distributed over the year, but the percentage infiltrating to form groundwater varies quite sharply. Some 61% of infiltration occurs in the four winter months November to February, when agricultural activities are low. Only 10% infiltrates in the four summer months, May to August, when agricultural activities are high. In all, annual groundwater amounts to some 24.8 km3, of which 50% is considered to be recoverable. Capital groundwater reserves must be large, but are unquantified. Under these conditions, the impact of agriculture on groundwater quantities is negligible. Of the annual extraction of some 170 × 106m3 of groundwater, some 66 × 106m3/year are used in different agricultural activities. Drainage operations, however, have effects on Irish groundwater. Such lands may overlie impermeable strata or pans, or may receive concealed or visible groundwater discharge. Their drainage will affect the groundwater in various ways. There has been a considerable impact of agriculture on groundwater quality. The effects on the atmosphere and on precipitation are not identifiable. Effects of diffuse infiltration are treated with respect to: (a) application of ground limestone (lime); (b) application of K.N.P. inorganic fertilizer; (c) spreading of organic slurries; (d) development of organic nitrogen in soils, mainly after ploughing of grasslands; and (e) residues from herbicides, fungicides, and pesticides. The infiltration of these substances spread on the land is closely related to the interaction between times of ground-water recharge and times of fertilizer application. Effects of concentrated infiltration are treated under seven sub-heads: (a) infiltration of polluted surface waters; (b) localized farm infiltration; (c) concentrated waste disposal from feedlots; (d) concentrated waste disposal from silage; (e) concentrated waste disposal from agro-industries; (f) disposal through sinkholes and quarries; and (g) disposal by deep well injection. These operations are deliberate, and not related to times of groundwater recharge. They are often into the limestone aquifers, and so doubly dangerous. 相似文献