Dominguez Mariani, 2004

7/30/2019 Dominguez Mariani, 2004

1/17

WASTEWATER REUSE IN VALSEQUILLO AGRICULTURAL AREA,

MEXICO: ENVIRONMENTAL IMPACT ON GROUNDWATER

E. DOMNGUEZ-MARIANI, A. CARRILLO-CHVEZ, A. ORTEGA andM. T. OROZCO-ESQUIVEL

Centro de Geociencias-UNAM, Campus Juriquilla, Juriquilla, Quertaro, 76230, Mxico

( authors for correspondence, e-mail: [email protected] and

[email protected])

(Received 27 June 2002; accepted 30 December 2003)

Abstract. Wastewater and groundwater has been used for irrigation in the Valsequillo District, eastcentral Mexico, for nearly 50 years. The environmental impact of wastewater on groundwater in theunconfined shallow aquifer is evaluated by means of hydrogeological, microbiological, hydrogeo-

chemical and isotopic evidences. The shallow aquifer consists of upper Tertiary volcano-sedimentaryrocks with a calcite-rich matrix. Groundwater from wells near the wastewater canal had similartotal coliforms concentrations as the wastewater (100 MPN 100 mL1). The hydraulic head innear-canal wells had a recovery of 10 m until 1983, indicating shallow recharge from wastewater.A bicarbonate vs. calcium plot shows a well-defined mixing process between wastewater and unaf-fected groundwater. Stable isotopic data (D and 18O) show characteristic signatures for wastewaterand non-impacted groundwater, and define a mixing line between those end-members and ground-water affected by wastewater infiltration. Tritium data indicate that non-impacted groundwater ispre-atomic hydrogen bomb (>50 yr), whereas the wastewater has a younger signature. Tritiumdata from wells inside the district clearly indicate a mixing process between waste and groundwater.These results demonstrate the interaction and hydrochemical processes between wastewater andshallow groundwater at the site.

Keywords: groundwater, irrigation, Mexico, mixing processes, reuse water, Tecamachalco, Valse-

quillo, wastewater

1. Introduction

The growing demand of water for agricultural irrigation has produced a markedincrease in the reuse of treated and/or untreated industrial wastewater worldwide.The effects of industrial and municipal wastewater on agricultural soils have beenwidely documented, mostly in relationship with heavy metal concentrations (Fazelliet al., 1991; Boon and Soltanpour, 1992; Rao et al., 1993) and toxicological studies.However, the environmental impact of irrigation wastewater has not been widelyinvestigated.

In this paper we present new hydrogeological and hydrogeochemical data, aswell as a general description of a conceptual model for the interaction betweenreused wastewater from the city of Puebla, central Mexico, with the shallow aquiferof Tecamachalco.

Water, Air, and Soil Pollution 155: 251267, 2004. 2004 Kluwer Academic Publishers. Printed in the Netherlands.


2/17

252 E. DOMINGUEZ-MARIANI ET AL.

The city of Puebla (1.3 million of inhabitants in 2000, 26% of the state popu-lation) is located in a valley on the volcanic highlands of east central Mexico. Theestimated industrial growth of 60% for the last 20 yr (INEGI, 2000) in this city ismainly related to its vicinity to Mexico City valley, where growing environmentalproblems have forced industrial decentralization.

In Mexico, industrial and municipal wastewater has been widely used for sev-eral years for agriculture. The best known case is the Mezquital basin, north ofMexico City, where 45 m3 s1 of wastewater from Mexico Citys metropolitanarea are used for agricultural irrigation (ERNR, AIC and ANI, 1995; Chilton et al.,1996). Similar practices take place at a smaller scale in the nearby cities of Puebla,Cuernavaca, Toluca and Pachuca. The environmental impact of the wastewaterreuse at these places has been recently recognized as a major problem that needs amultidisciplinary approach for its evaluation.

The purpose of the present work is to evaluate the hydrogeologic and hydrogeo-chemical interaction between wastewater used in the Valsequillo Irrigation District

and groundwater from the shallow aquifer. We also propose a general hydrogeo-logic-hydrogeochemical conceptual model of this interaction. This work is part ofa major research project, designed to analyze the interaction between wastewaterfrom the irrigation canal and groundwater from the shallow aquifer.

2. Site Description and Geologic-Environmental Background

The Valsequillo Irrigation District (2000 m a.s.l.) is located on the high plains ofcentral-east Mexico, 30 km southeast from the city of Puebla (Figure 1), in a broadvalley (260 km2) bordered by two large volcanoes: the Malinche volcano to the

northwest, and the Citlaltpetl volcano to the northeast.The stratigraphy of the area (Figure 2) is dominated by Cretaceous reefal lime-stones, interstratified limestones, shales, sandstones, and fine grained-limestoneunits (Units A and B in Figure 2). These units constitute a deep aquifer, withfew groundwater wells reaching it. This aquifer is confined by a massive, heavilypacked, well-consolidated conglomerate of Tertiary age (Unit C, thickness 200 m).

Lava flows and volcanic breccias (Unit D), and non-consolidated carbonate-richvolcanoclastic rocks from Late Tertiary and Quaternary (Unit E), constitute theupper 100200 m of the stratigraphic column. The most productive groundwaterwells are located in those uppermost volcano-sedimentary units that constitute theshallow aquifer. This aquifer has secondary permeability due to the developmentof dissolution canals, fractures, and matrix porosity.

The Valsequillo Irrigation District, located within the basin of the lower AtoyacRiver, started the irrigation operations in 1946. Until 1975, the water was sup-plied mainly by the Valsequillo reservoir, and subsequently was complementedby groundwater from drilled wells (Figure 3). The Valsequillo reservoir supplies163 m3 yr1, and additional 55 m3 yr1 are withdrawn from wells for the irriga-


3/17

WASTEWATER REUSE IN VALSEQUILLO AGRICULTURAL AREA, MEXICO 253

Figure 1. Generalized map of the Atoyac River in central Puebla State, Mexico (inset), the Valsequillodam and the Valsequillo Irrigation District. The study is centered on Unit 1 of the irrigation district,east of Tecamachalco (boxed area). The irrigation dam of Valsequillo was built south of the city ofPuebla, where the Alseseca River ends in the Atoyac River. Numbers 1 to 7 indicate surface water

sampling sites (data from PDRA, 1995).

tion of a total of 33 820 ha. The relative amount of water from the reservoir andfrom groundwater used in irrigation varies every year, depending on the amount ofwater accumulated in the reservoir. Since 1960, untreated industrial and municipalsewage water from the city of Puebla has been discharged in minor scale into theAtoyac River, and is finally conducted to the Valsequillo reservoir (Contla, 1976).By 1976, as the dam was at its lowest level, due in part to poor water-use andconservation planning, the induction of a drilling program was necessary (Contla,1976; SARH, 1973, 1974a, b, 1976, 1979 and 1982a). Since 1976, the size of thesurface irrigated has varied every year according to the storage water in the damand the groundwater extraction. By 1978, the piezometric level has ascended due tothe amount of surface water used for irrigation, which was an additional componentof shallow recharge. Variations on stable isotope compositions were also noticed(SARH, 1979, 1982b).


4/17


Figure2.Geologicmapofthestudyarea,includingvalues

ofhydraulichead(m),directionofgroundwaterflow,andlocalstratigraphiccolum

n(seetextfor

discussion).Loca

lizationofsamplingsitesofirrigationgro

undwaterandsurfacewaterisshowninthemap.HydraulicheaddatafromCNA(1995,1996).


5/17


Figure 3. (A) Evolution of piezometric levels in sites of piezometric observation (SPO) with time.Location of SPO is showed in Figure 1. (B) Evolution of groundwater withdrawal and number ofwells. Data from SARH (1974, 1989) and CNA (1996).


6/17


In the early 1980s, formal hydrogeology and hydrogeochemistry studies beganbeing conducted in this area. In 1994, the extension of the irrigation area reachedits maximum, in coinciding with the drilling of wells and the extraction volume.In 1984, it was estimated that 30% of the total volume of water in the Valsequillodam came from industrial and municipal sewage water (Orta-Ledezma, 1985).

The water is conducted from the dam to the irrigation district by a surface canal,which is cement-lined in only 42% of its 15 km length. Studies show that consid-erable loss of water through the unlined canal walls results in infiltration to thegroundwater system (CNA, 1996). However, no instrumentation has been availableat the site to measure the infiltration volume of wastewater from the canal.

3. Methods

From December 1995 to January 1996, 48 samples of water were collected in the

area: 44 from groundwater wells and 4 from canal water. Groundwater sampleswere taken from productive irrigation wells located inside and outside the dis-trict. Water samples were collected for chemical (major and trace elements), iso-topic (D, 18O and tritium), and microbiological analyses. Temperature, electricconductivity, pH, and alkalinity (acid-base titration to pH = 3.5) were directlymeasured in the field. Samples were filtered through 0.45-micron Millipore filters,collected in double acid washed, high-density polypropylene opaque bottles, andconserved at 4 C until they were analyzed. Major dissolved ions and microbiolo-gical analyses were done in the Laboratorio de Edafologa Ambiental, Instituto deGeologa, UNAM-Mxico. Isotopic analyses (oxygen and hydrogen stable isotopes)were done at the Laboratorio Universitario de Geoqumica Isotpica (LUGIS),

Instituto de Geologa-Instituto de Geofsica, UNAM-Mxico, with the technique ofEpstein and Mayeda (1953) for 18O and the technique of Coleman et al. (1982)for D. Tritium samples were analyzed at the Environmental Isotope Laboratory(EIL), University of Waterloo (Canada), following the method proposed by Taylor(1977).

4. Results and Discussion

4.1. EVOLUTION OF THE PIEZOMETRIC SURFACE

Six sites were selected for piezometric observations (SPO1-6, see Figure 2 forlocation) on the basis of well density, hydraulic head, and location with respect tothe wastewater canal.

Figure 3A shows a plot of time (years) vs. hydraulic head (m asl) for the sixsites of piezometric observations (SPO). Site SPO1 (Figures 2 and 3A) presents thehighest increase in hydraulic head with time, most likely because it is located near


7/17


the wastewater canal and have a major influence from irrigation and infiltration.Site SPO6, located on the southest end of the irrigation district, shows no variationin hydraulic head, probably due to lesser influence from infiltration of wastewater.Figure 3A indicates a variation of hydraulic head with time due to local rechargefrom infiltration, and a decline in hydraulic head due to increasing extraction donesince 1974. The major recovery occurred during the 19741983 period. After 1983,the increase in groundwater pumping has caused a general decline in hydraulichead. The data of Figure 3A can be summarize as follow:

(1) As groundwater extraction started (on early 1970s), the effect of infiltrationwas negligible.

(2) During the early 1970s, when mainly dam water and wastewater was usedfor irrigation, the infiltration reached its maximum, causing a rise in hydraulichead.

(3) After 1983, irrigation was mainly done with groundwater, causing the declin-

ing trend in hydraulic head in all the sites of piezometric observation.

From 1983 to 1988, the mean decline in hydraulic head was of 10 m, and between1988 and 1996 had achieved more than 15 m (Figure 3B shows the increasingnumber on groundwater wells, and the increase in groundwater withdrawal volumevs. time). An increase in the slope of both curves indicates the increase in ground-water withdrawal after 1985.

4.2. WATER QUALITY VARIATIONS

The contaminant load discharged from the Valsequillo reservoir into the canal is,

in terms of biologic oxygen demand (BOD5), 1125 mg L1

(Rodrguez-Velasco,1996). This value is considered a high concentration (averages values of BOD5are: 110 mg L1 = low; 220 mg L1 = medium; 400 mg L1 = high; Tchbano-glous, 1991). Therefore, due to this high values and the high concentration ofdissolved heavy metals and other ions (i.e., Cd, Pb, Cr, Co, As, Fe, Mn, and NO 3 )(PDRA, 1995), the canal wastewater is actually not suitable for agricultural use(Orta-Ledezma, 1985; NOM, 1997).

The Atoyac River, the main water supply of the Valsequillo dam, collects refusewater from the Puebla municipal discharge. Figure 4A,B and C show the concen-tration of total and fecal coliforms, specific conductance, and NO3-N and NH4-Nmeasured along the Atoyac River. The sampling points are located: before enteringto the city of Puebla (sites 1, 2 and 3), between the city and the dam (sites 4 and5), after the dam (site 6), and in the open unlined canal (site 7). Figure 4A showsa sudden decrease in coliforms bacteria immediately after the Valsequillo dam.The amount of total coliforms is relatively high in the Atoyac River (Figure 4A,sites 1, 2 and 3), and remains high at sites 4 and 5. The values in these sites varyfrom 1 108 to 1 1010 MPN 100 mL1. When water flows out of the dam and


8/17


Figure 4. Sections from High Atoyac River to Valsequillo dam in points showed in Figure 1 (see textfor discussion). (A) Total and fecal coliforms; (B) Specific conductance; (C) NO3-N and NH3-N.Data from PDRA (1995).


9/17


enters the canal, the coliforms decrease to approximately 1103 MPN 100 mL1;we consider that this is the total coliforms value of the canal water infiltratingin the groundwater system. The effect of decreasing values after the dam is alsoobserved in the behavior of the specific conductance (amount of total dissolvedsolids in water, Figure 4B), and NO3-N and NH4-N in solution (Figure 4C). Thisbehavior indicates that the Valsequillo dam is acting as a giant open-batch biore-actor, oxidizing the wastewater, and decreasing the amount of coliforms introducedby the municipal discharges. Dilution, precipitation, adsorption, and other similarprocesses, which take place in the Valsequillo dam, control the hydrogeochemistryof the system and improve the quality of the water.

Total coliforms and fecal bacteria were also analyzed in groundwater samples.Figure 5 shows a contour map of the concentration of total coliforms (in MPN100 mL1) in groundwater of the Valsequillo Irrigation District. The highest val-ues of total coliforms in groundwater (1000 MPN 100 mL1) are observed on thenorthwest portion of the irrigation district, and are similar to the average value in

the last section of the canal (after water has been in the Valsequillo dam). Thesehigh values of total coliforms coincide with the location of site SPO1, which alsoshows the strongest effect in vertical local recharge and rise of hydraulic head. Thecoincidence of strong rise in hydraulic head and high total coliforms concentrationindicate a high infiltration velocity that would favor the preservation of microorgan-isms in the aquifer. This observation contradicts the conclusion of Orta-Ledezma(1985), who considered that the aquifer would not be affected by irrigation waterbecause of its relative depth and the clayey and silty nature of the aquifer material.

4.3. CARBONATE AND CALCIUM BEHAVIOR

In the northern section of the study area (north of the canal), only groundwaterhas been used for irrigation and, apparently, no influence from canal wastewateris observed. Although, the possibility of some local infiltration in near-canal areasremains, because no specific studies have been performed in that areas. In thiswork, we assume that wastewater has no influence on the groundwater from thenorthern sector.

The unaffected groundwater in the northern section is classified as a bicarbon-ate type of water, with HCO3 concentrations ranging between 7 to 11 meq L

1

(Figure 6), and Ca2+ that varies from 9 to 16 meq L1. On the other hand, thecanal water (wastewater), is carbonate-poor water, with concentrations of HCO3and Ca2+ ranging between 44.2 meq L1, and 2.63 meq L1, respectively. Thesetwo types of water can be assumed as end-members of a water mixing system.Figure 6 shows that values of HCO3 and Ca

2+ in groundwater samples affectedby wastewater infiltration are located between the values of surface water (canalwastewater) and unaffected groundwater defining a mixing trend.


10/17


Figure

5.Contou

rmapofiso-concentrationlinesfortotalcoliforms(MPN

100mL1)ingroun

dwaterofValsequilloIrrigationDistrict(seetextfor

discussion).Data

fromCNA(1995).


11/17


Figure 6. Plot of Ca2+ vs. HCO3 (meq L1) for groundwater and surface water of Valsequillo Irrig-

ation District. The end-members (wastewater and unaffected groundwater) define a mixing process.Data from CNA (1995).

4.4. STABLE ISOTOPES

The results of isotope analyses in canal wastewater and groundwater are showed ina plot ofD () vs. 18O () (Figure 7A). Groundwater samples from the north-ern section, with no influence of wastewater (wells P3, P2Z and P47.3, see Figure 2for location) plot on the Global Meteoric Water Line (GMWL), and represent thefirst end-member in a binary water-mixing process. On the other hand, the isotopiccomposition of canal wastewater plot away from the GMWL, with higher 18Oand D, this composition is considered as the second end-member of the binarymixing process. The mixing line delineated between these end-members has theexpression D= 4.91318O 23.054; groundwater samples with influence fromwastewater plot along a mixing line, indicating that they are the result of mixingprocesses.

Figure 7B shows a plot of 3H (tritium) vs. 18O() only for samples plottingin the mixing line. Groundwater from the northern section, with no canal waterinfluence, has 3H values of


12/17


Figure 7. Isotopic analysis of ground and surface water from Valsequillo Irrigation District. (A) 18O() vs. D () for all points sampled; (B) Plot of18O () vs. 3H (UT) including samples thatplot along the mixing line of Figure 7A. Data from CNA (1995).

hand, groundwater with influence of canal water (mixing processes, wells P911,P4B, P28 and P111B) show an increase in values of3H.

Surface water collected in the Valsequillo dam, and eventually conducted

through irrigation canals to the district, is dominated by meteoric water from theAtoyac Basin with an important contribution of municipal wastewater from thecity of Puebla. Thus, the tritium values in the canal water would indicate relativelyyoung water due to recent precipitation and infiltration. This process is indicatedby the values showed in Figure 7B, where the groundwater affected by canal waterhas values ranging between 3 and 7 TU. If the tritium values of affected ground-water are the result of a mixing process, then the canal water should have tritiumvalues lower than 10 TU. Such values would correspond to water ages rangingbetween the mid 1970s and the mid 1980s. This age agrees with the beginningof the hydraulic head rise (mid-late 1970s), due to wastewater infiltration intogroundwater (Figure 3A). Therefore, tritium data clearly show the impact of canalwater on groundwater from the Valsequillo Irrigation District.


13/17


Figure 8. Schematic cross section of Valsequillo Irrigation District, showing the general hydrostrati-graphic units and the sources of wastewater and groundwater used for irrigation. Inset shows thelocation of the section in Valsequillo Irrigation District.

4.5. CONCEPTUAL MODEL FOR THE INTERACTION BETWEEN WASTEWASTEAND GROUNDWATER

Figure 8 shows a schematic representation of the interaction processes between thewastewater from the irrigation canal and the groundwater from the Valsequillo Ir-rigation District. This scheme indicates the different hydrostratigraphic units of thesub-surface. The uppermost unit (E) represents the main aquifer in the zone, whichis composed by a Pleistocene-Quaternary volcano-sedimentary unit of about 100200 m in thickness. The hydrogeochemical processes taking place in this unit aremixing of wastewater and groundwater, advection, molecular diffusion, dilution,etc. The next unit stratigraphically below is an aquitard in fractured lava flows andvolcanic breccias (unit D) of Miocene-Pleistocene age. This unit outcrops in thestudy area as isolated domes and is covered by unit (E). The extension of unit D inthe sub-surface is unknown, but it is probably connected at depth to other igneousbodies forming sub-surface structures of lower hydraulic conductivity. Such struc-


14/17


tures would be acting as an irregular and discontinuous barrier for groundwaterlateral flow. The next unit (lettered C) is an aquitard in a heavily packed, wellcemented, strongly consolidated conglomerate sequence of possible Oligocene-Miocene age. This unit confines the Shallow Aquifer. Most of the drilled wellspenetrated just a couple of meters into this unit before stopping. Finally, (lowerunit, AB) is a fractured aquifer composed by a sequence of reefal and inter-stratified limestones, shales and sandstones and a fine grained-limestones from theUpper Aptian to Maastrichian (Upper Cretaceous). Only in the southest extreme ofthe area few wells are drilled in this unit, which is considered as the Deep Aquifer,separated from the Shallow Aquifer (unit E) by an aquitard (unit C). As mentionedabove, we considered that most of the hydro-geochemical processes are takingplace on the water table of the shallow aquifer. In the non-saturated zone, the canalwastewater moves down and interacts with the calcareous matrix of the aquifer.When the wastewater reaches the water table, a mixing process begins, dilutingthe wastewater, which is evidenced by the bicarbonate and calcium concentrations,

and the 2D, 18O and tritium data. The occurrence of advection and diffusionprocesses is indicated by the distribution of total coliforms in groundwater.

The irregular distribution of the volcanic bodies in the sub-surface (volcanicaquitard) could explain the low tritium and total coliforms concentrations in wellslocated in this unit, because this unit acts as an irregular lateral barrier.

5. Conclusions

Studies of reuse of non-treated wastewater on agriculture have been mostly doneregarding the effect upon the environment, including soils, plants and human health.

However, studies about its influence in the chemistry of groundwater are scarce.Therefore, our approach is important for evaluation studies at sites where non-treated wastewater is used for irrigation and the collateral effects are still unknown.

The Valsequillo water reservoir has been receiving surface water from theAtoyac and Alseseca rivers, municipal-industrial refuse water from the urban zoneof the city of Puebla and from some rural areas from north of Puebla for more than50 yr. Despite the fact that the Valsequillo dam performs as a big bioreactor, thesurface water preserves a high load of contaminants through irrigation canals to theValsequillo District.

The studied area has two aquifers: (1) a Shallow aquifer in a Tertiary-Quaternarydeposit, where most of the productive wells are located; and (2) a Deep aquiferin Mesozoic limestones, used in a minor scale in the zone. The Shallow aquiferconsists of a volcano-sedimentary deposit with calcareous matrix. Because of itshigh solubility and additional fracturing, this aquifer has double porosity, whichimplies fast infiltration of wastewater toward the saturated zone.

Outside of the irrigation district, only groundwater is used. Therefore, this zoneis considered not affected by wastewater. The chemical composition of ground-


15/17


water permits the identification of hydrogeochemical and isotopic baseline data,which is the original composition in the aquifer before the irrigation with waste-water began.

Four types of interactions have been identified between groundwater and waste-water: (a) hydrogeological, (b) microbiological, (c) hydrochemical, and (d) iso-topic.

During the 70s, high volumes of surface water were used for irrigation onhigh hydraulic conductivity materials, favoring the recovery of water table levels.Therefore, the irrigation is an important component of the groundwater recharge.The response to this artificial recharge varied at different points of the irrigationaldistrict, e.g., hydraulic head measured between 1975 and 1980 shows an incrementof more than 10 m close to the irrigation canal (SPO1, SOP2, SOP3), and of lessthan 4 m in the southern part of the aquifer (SOP4).

The agricultural district is irrigated with 70% wastewater and 30% groundwaterfrom the Shallow Aquifer. In years of low disponibility of surface water, the district

uses a higher volume of groundwater. This has caused extensive use of ground-water, leading to a decrease of the piezometric levels. The rates of descent of thegroundwater levels depend on different responses of the aquifer to exploitation.These responses correlate with the characteristics of the geologic media and re-charge components (infiltration from the irrigation canal, from agricultural surfaceand lateral underground flow).

Total coliforms have been detected in groundwater in concentrations that makesit unfit for supply of potable water. This fact is directly associated with the mix-ing with wastewater. The short periods of survival of the microorganisms, likethe coliform group, indicate relatively fast infiltration through macropores and/orfractures.

Plots of calcium (Ca

2+

) and bicarbonate (HCO

3 ) concentrations show two well-defined end members. Surface water has lower concentrations for both ions, whilethe baseline (unpolluted groundwater) data has higher concentrations. Evidence ofinfiltration and mixing of wastewater with groundwater is clear in these plots.

Stable isotopic data (D and 18O) shows that non-impacted groundwater plotson the Global Meteoric Water Line (GMWL), while wastewater data plot awayfrom the GMWL line. Intermediate values are interpreted as an evidence of mix-ing between the two end members. Tritium values below 0.8 TU are associatedwith non-impacted groundwater with pre-atomic hydrogen bomb age, whereasthe canal water has a younger signature (higher TU values). Stable isotopes andtritium data defined two types of recharge water: (1) meteoric pre-atomic waterwith


16/17


Acknowledgements

This work was funded in part by Ph.D. scholarship 93725 from CONACyT-Mxicoand Grants 030607 and 103308 from PAEP-UNAM. The authors wish to thankthe Comisin Nacional del Agua-Mxico (CNA) for allowing the use of their data.Finally, the authors also wish to express special thanks to Pedro Morales y a EdithCienfuegos for isotopic analyses, and to the anonymous reviewers of the finalmanuscript.

References

Boon, D. Y. and Soltanpour, P. N.: 1992, Lead, cadmium and zinc contamination of aspen gardensoils and vegetation, J. Environ. Qual. 21, 8286.

Clark, I. D. and Fritz, P.: 1997, Environmental Isotopes in Hydrogeology, Lewis Publishers, BocaRaton, pp. 328.

Comisin Nacional del Agua (CNA): 1995, Estudio de la Migracin de Contaminantes haciael Acufero Regional Derivados del Riego con Aguas Residuales del Distrito de Riego deValsequillo, Puebla, Technical Report, Comisin Nacional del Agua, Mxico, D.F., pp. 56.

Comisin Nacional del Agua (CNA): 1996, Actualizacin Geohidrolgica del Acufero de Te-camachalo, Puebla, Mxico, Technical Report, Comisin Nacional del Agua, Mxico, D.F.,pp. 167.

Coleman, M. L., Sheperd, T. J., Durham, J. J., Rouse J. E. and Moore, G. R.: 1982, Reduction ofwater with zinc or hydrogen isotope analysis, Anal. Chem. 54, 993995.

Contla, C. R.: 1976, La importancia econmica de los Distritos de Riego en Mxico, el caso del Dis-trito de Riego de Valsequillo, Puebla, B.S. Thesis, Universidad Nacional Autnoma de Mxico,Fac. de Economa, Mxico, D.F., pp. 141.

Chilton, P. J., Morris, B. L. and Foster, S. S. D.: 1996, Impacto del reuso de las aguas resid-uales sobre el agua subterrnea en el Valle del Mezquital, Edo de Hidalgo, Mxico, in VIII

Curso Internacional Los Recursos Hdricos Subterrneos y la Disposicin de Aguas Resid-uales Urbanas. Interacciones Positivas y Negativas, 3643, Quertaro, Mxico, 6 March 1996,Organizacin Mundial de la Salud, el Programa de las Naciones Unidas para el Medio Am-biente, Organizacin Panamericana de la Salud, Centro Panamericano de Ingeniera Sanitaria,Overseas Development Administration, British Geological Survey (OMS-PNUMA-GEM/OPS-CEPIS/ODA-BGS), Quertaro, Mxico.

Environment and Resources National Research Council, Academia de la Investigacion Cientficaand Academia Nacional de Ingeniera (ERNR, AIC and ANI): 1995, El Suministro de Agua dela Ciudad de Mxico, National Academy Press, Washington, D.C., pp. 114.

Epstein, S. and Mayeda, T. K.: 1953, Variation 18O/16O ratio in natural sources, Geochim.Cosmochim. Ac. 4, 213224.

Fazeli, M. S., Sathyanarayan, S., Satish, P. N. and Muthana, L.: 1991, Effects of paper mill ef-fluents on the accumulation of heavy metals in coconut trees near Nanjangud, Mysore District,Karnatake, India, Environ. Geol. Water S. 17, 4750.

Instituto Nacional de Estadstica, Geografa e Informtica (INEGI): 2000, Indicadores de DesarrolloSustentable en Mxico, www.inegi.gob.mx/, May, 2002.

Norma Oficial Mexicana (NOM): 1997, Norma Oficial Mexicana NOM-001-ECOL-1996. QueEstablece los Lmites Mximos Permisibles de Contaminantes en las Descargas de Aguas Re-siduales en Aguas y Bienes Nacionales, Diario Oficial de la Federacin (DOF), Mxico, 6January 1997, pp. 6885.


17/17


Orta-Ledezma, M. T.: 1985, Criterios para el Aprovechamiento de Aguas Residuales en Riego Agr-cola en Mxico, M.Sc. Thesis, Fac. de Ingeniera, Divisin de Estudios de Posgrado, UniversidadNacional Autnoma de Mxico, Mxico, D.F., pp. 112.

Programa de Desarrollo Regional Angelpolis (PRDA): 1995, Estudio de Factibilidad del Proyecto

de Restauracin de la Presa Valsequillo, Puebla, Technical Report, Gobierno del Estado dePuebla, Programa de Desarrollo Regional Angelpolis, Puebla, Mxico, pp. varia.Rao, A. V., Jain, B. L. and Gupta, I. C.: 1993, Impact of textile industrial effluents on agricultural

land Case study, Indian J. Environ. Health 35, 132138.Rodrguez-Velasco, F. M.: 1996, Caracterizacin Fisico-Qumica de la PresaManuel vila Camacho

Valsequillo y Planteamiento de una Planta para Tratamiento del Agua, B.S. Thesis, Fac. deCiencias Qumicas, Benemrita Universidad Autnoma de Puebla (BUAP), Mxico.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1973, Estudio geohidrolgico de la re-gin de Palmar de Bravo y Esperanza, Technical Report, Secretara de Agricultura y RecursosHidrulicos, Mxico, D.F.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1974a, Estudio Geohidrolgico Prelim-inar de las Zonas de Tepeaca y del Distrito de Riego de Valsequillo en el Estado de Puebla, I andII, Technical Report, Secretara de Agricultura y Recursos Hidrulicos, Mxico, D.F.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1974b, Estudio Geohidrolgico de la

Regin de Palmar de Bravo y Esperanza, Edo. de Puebla. Segunda Etapa, Technical Report,Secretara de Agricultura y Recursos Hidrulicos, Mxico, D.F.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1976, Estudio Geohidrolgico Detalladode Zonas Secas, Valsequillo, Puebla, Technical Report, Secretara de Agricultura y RecursosHidrulicos, Mxico, D.F.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1979, Algunos Aspectos de la Geohidro-loga Isotpica de la Regin de Valsequillo, Puebla, Technical Report, Secretara de Agriculturay Recursos Hidrulicos, Mxico, D.F.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1982a, Actualizacin de los Vallesde Palmar de Bravo y Esperanza, Technical Report, Secretara de Agricultura y RecursosHidrulicos, Mxico, D.F.

Secretara de Agricultura y Recursos Hidrulicos (SARH): 1982b, La Hidrologa Isotpica delas Aguas Subterrneas de la Porcin Central de Mxico, Technical Report, Secretara de

Agricultura y Recursos Hidrulicos, Mxico, D.F., pp. 25.Taylor, C. B.: 1977, Tritium Enrichment of Environmental Waters by Electrolysis: Development ofCathodes Exhibiting High Isotopic Separation and Precise Measurement of Tritium EnrichmentFactors, Proceedings of the International Conference of Low-Radioactivity Measurements andApplications, Bratislava, Slovenski Pedagogicke Nakladatelstvo, pp. 131125.

Tchobanoglous, G. and Burton, F. L.: 1991, Metcalf & Eddy Wastewater Engineering: Treatment,Disposal and Reuse, 3rd ed., McGraw-Hill Inc., New York, pp. 1334.

Documents

Dominguez Mariani, 2004