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Domestic Wastewater as a Source of Contaminants in Freshwater Aquifers
in the Mayan Riviera Tourism Region of Mexico
Chris Metcalfe1, Gerardo Gold Bouchot2, Tracy Metcalfe1, Hongxia Li1, Patricia Beddows3 and Hanneke Van Lavieren4
1) Marine Sciences Laboratory, CINVESTAV, Merída, Yucatan State, Mexico2) Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL, USA3) Worsfold Water Quality Centre, Trent University, Peterborough, ON, Canada4) UN University – International Network for Water Environment and Health, Hamilton, ON, Canada
In this pilot study, we evaluated whether contamination is currently
Table 1: Target analytes sampled by SPMDs and POCIS, sources of
occurring in the Mayan Riviera region by monitoring selected
Passive Sampler Deployment Locations
contamination, methods of analysis and lead analytical laboratory.
December 2008 to January, 2009
fresh water discharge zones using passive sampler technologies.
The fresh water resources within the highly permeable karst
We have previously used semi-permeable membrane devices
geology of the Yucatan Peninsula of Mexico are vulnerable to
(SPMDs) to monitor aquatic environments for water insoluble (i.e.
contamination from agricultural, industrial and urban
hydrophobic) contaminants, such as PCBs, organochlorine
pesticides (OCs) and polycyclic aromatic hydrocarbons (PAHs),
Caribbean coast of the Yucatan Peninsula is one of the
as well as surfactants and pesticides applied to golf courses
fastest growing tourism areas in Mexico. There is evidence
(Bennett and Metcalfe, 2000; Metcalfe et al., 2000; O’Toole et al.,
5 cave systems
that tourism and recreational development in this region is
41+ km of caves
2006; Metcalfe et al., 2008). More recently, a passive sampler was
Car wash cenote
being poorly managed, and there is inadequate infrastructure
developed for more water-soluble (i.e. hydrophilic) contaminants.
13 cave systems
for the treatment of domestic sewage and control of urban
This Polar Organic Chemical Integrative Sampler (POCIS) shows
1) Ak Tulum cave
348+ km of caves
2) Herradura cave
runoff. Therefore, tourism may be a significant threat to the
promise as a monitoring tool for polar contaminants, such as
The 3 largest subterranean rivers in the world, and the
largest cave in Mexico
quality of fresh water resources in the region, and may also
pharmaceuticals, current use pesticides and endocrine disrupting
impact the marine environment as a result of discharges of
compounds (Petty et al., 2004; Burki et al., 2006; MacLeod et al.,
contaminated fresh water into the coastal zone. In this pilot
Figure 2: Locations for the deployment of passive samplers in
study, we monitored fresh water aquifers for evidence of
cave systems near Tulum and Puerto Aventuras in the Mayan
contamination by deploying passive samplers in cave systems located at two sites along the Caribbean coast of the Yucatan
Sample preparation and analysis
Peninsula (i.e. Tulum, Puerto Aventuras). The passive
Flow of Fresh Water and Salt Water
Results and Discussion
and Potential Pathways for
samplers sequestered contaminants from the water over a
The SPMD and POCIS passive samplers were retrieved in early
Several compounds of domestic wastewater origin, including caffeine,
one month deployment period from early December, 2008 to
January, 2009 and were immediately transported to the
cotinine, non-prescription and prescription drugs, and cocaine were
early January, 2009. Analysis of extracts indicated that the
CINVESTAV research institute in Merida, Mexico for extraction.
detected in extracts from passive samplers deployed in cave systems
passive samplers accumulated detectable amounts of
The SPMDs were dialyzed into hexane as described previously
near Tulum and Puerto Aventuras (Figure 4).These data indicate that
stimulants (e.g. caffeine), prescription and non-prescription
by Metcalfe et al. (2000) and the POCIS adsorbent was extracted
domestic sewage is contaminating the fresh water aquifers in the
drugs and illicit drugs (e.g. cocaine), which could only have
into methanol as described by Petty et al., (2004). The extracts
region. The contaminants may then be discharged into the coastal
originated from domestic sewage. Contamination of the
from the SPMDs and POCIS were then transported to Trent
marine zone. Modes of contamination by sewage could be through
aquifer by sewage may be occurring as a result of the practice
University in Canada, where they were processed for analysis of
injection of wastewater into the salt water layer, leaky septic or
of injecting domestic wastewater into the salt water zone,
various classes of contaminants that indicate sources of
sewage distribution systems or through the widespread use of treated
leakage from sewage lines and septic systems, or by the use
contamination (Table 1). Co-extractives were removed from the
sewage for irrigation of the turf on golf courses. This contamination
of wastewater for irrigating the turf on golf courses. Results
Flow of fresh water
SPMD extracts by gel permeation chromatography (GPC). After
Flow of salt water
problem points to the need for more effective sewage management
are pending for the analysis of other classes of compounds
GPC, some extracts were fractionated by silica gel
systems and the installation of liners to protect fresh water aquifers.
that may indicate other sources of contamination.
chromatography and analyzed for PCBs and OCs by gas
Data are pending for the other classes of compounds that may
chromatography with an electron capture detector (GC-ECD) and
Figure 1: Flow of fresh water and salt water in the karst geology
indicate other sources of contamination.
for PAHs by gas chromatography and mass spectrometry (GC-
near the coastal region of the Yucatan peninsula in Mexico. The
MS). Other extracts were analyzed for synthetic musk fragrances
green arrows show potential pathways for contamination as a result of injection of wastewater into the salt water layer.
by GC-MS or for phenolic estrogens by liquid chromatography
Drugs and Stimulants
with tandem mass spectrometry (LC-MS/MS). POCIS extracts
Acetaminophen = Analgesic (i.e.Tylenol)
The geology of the Yucatan peninsula in Mexico consists of
were analyzed by LC-MS/MS for stimulants (caffeine, cotinine),
Naproxen = Anti-inflammatory
Ibuprofen = Analgesic (i.e.Advil)
prescription and non-prescription drugs, and illicit drugs (i.e.
Caffeine = Stimulant
Caribbean coast of the Yucatan peninsula, flooded caves
Cotinine = Metabolite of nicotine
provide a hydrological conduit that links the inland recharge
CBZ = Anti-epileptic (carbamazepine)
Total cocaine = Cocaine plus major metabolite,
areas to springs that discharge into the coastal zone.
Passive sampler deployment
Sinkholes called “cenotes” may also provide conduits for
An area of the Mayan Riviera on the Caribbean coast, south of
direct recharge into these cave systems. The regional
Playa del Carmen was selected for the deployment of passive
municipality of Solidaridad along the “Mayan Riviera” region
samplers. The geology of this region is characterized by
of Caribbean coast is a rapidly growing tourism and
numerous subterranean cave systems and cenotes; several of
recreational area. Planned expansion of tourist numbers and
which have been mapped and studied for their hydrogeology. As
Figure 4: Mean concentrations (ng/POCIS; n=3) of pharmaceuticals,
intensive land development south of Cancun means that
illustrated in Figure 2, passive samplers were deployed in 5 cave
stimulants and illicit drugs originating from domestic sewage detected in
the population will increase markedly over the next 20 years.
systems located near two areas: i) the small tourism center of
Domestic sewage effluents are currently pumped from
Tulum and ii) the gated recreational community of Puerto
municipalities and hotels into the saline zone below the
Aventuras. Passive samplers were deployed for a period of
Bennett, E.R. and C.D. Metcalfe. 2000. Environ. Toxicol. Chem. 19:784-792
Burki, R., E.L.M. Vermeirssen, O. Korner, C. Joris, P. Burkhardt and H. Segner. 2006. Environ. Toxicol. Chem. 25:2077-2086.
freshwater aquifer (Figure 1). As has been shown in the
approximately one month from early December 2008 to early
MacLeod, S.L., E.L. McClure and C.S. Wong. 2007. Environ. Toxicol. Chem. 26:2517-2529.
Florida Keys, this waste disposal practice has the potential to
Metcalfe, T.L., C.D. Metcalfe and E.R. Bennett. 2000. J. Great Lakes Res. 26:55-64.
January 2009. Three SPMDs and three POCIS samplers were
Metcalfe, T.L., P.J. Dillon, C.D. Metcalfe. 2008. Environ. Toxicol. Chem. 27:811-818.
contaminate the overlying freshwater aquifer and the coastal
housed in each stainless steel shroud (Figure 3). With the help of
O'Toole S., C.D. Metcalfe, I. Crane and M. Gross.
2006. Environmental Pollution 140: 99-110.
zone. In addition, there is potential for contamination of the
Petty, J.D., J.N. Huckins, D.A. Alvarez, W.G. Brumbaugh, W.L. Cranor, R.W. Gale, A.C. Rastall et al. 2004. Chemosphere 54:695-705.
certified cave divers, the samplers were deployed in the caves by
Figure 3: Stainless steel shrouds containing three SPMDs
aquifer from spills, irrigation, urban runoff or pesticide
and three POCIS passive samplers that were deployed in
Acknowledgements: Funding for this research was provided through a research grant from UNU-
tethering them to limestone features in the caves, or they were
cave systems in the Mayan Riviera region.
INWEH as part of a project funded by the Global Environmental Fund of the World Bank. Many thanks
to the certified cave divers, Dennis Weeks, Robert Schmittner and Jeff Clark, who helped to deploy the samplers.
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