Microbiological Implications of Periurban Agriculture and Water Reuse in Mexico City

BACKGROUND: Recycled treated or untreated wastewater represents an important health challenge in developing countries due to potential water related microbiological exposure. Our aim was to assess water quality and health implications in a Mexico City periurban agricultural area. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal study in the Xochimilco wetland area was conducted, and 42 sites were randomly selected from 211, including irrigation water canals and effluents of treatment plants. Sample collection took place during rainy and dry seasons (2000-2001). Microbiological parameters (total coliforms, fecal coliforms, streptococci/enterococci, and bacteria other than Vibrio grown on TCBS), Helicobacter pylori, and physicochemical parameters including trihalomethanes (THM) were determined. Fecal coliforms and fecal streptococci are appropriate indicators of human or animal fecal contamination. Fecal coliform counts surpass Mexican and World Health Organization irrigation water guidelines. Identified microorganisms associated with various pathologies in humans and domestic animals comprise Escherichia coli, Klebsiella spp., Salmonella spp., Enterobacter spp., Enterococcus spp., and Pseudomonas spp; H. pylori was also present in the water. An environmental characteristic of the canal system showed high Total Organic Carbon content and relatively low dissolved oxygen concentration; residual chlorine as a disinfection control is not efficient, but THMs do not represent a problem. During the rainy season, temperature and conductivity were higher; in contrast, pH, dissolved oxygen, ammonia, and residual chlorine were lower. This is related with the continuous load of feces from human and animal sources, and to the aquatic systems, which vary seasonally and exhibit evidence of lower water quality in effluents from treatment plants. CONCLUSIONS/SIGNIFICANCE: There is a need for improvement of wastewater treatment systems, as well as more efficient monitoring, regulation, and enforcement procedures for wastewater disposal into bodies of water

A Quantitative Approach to the Watershed Governance Prism: The Duero River Basin, Mexico

Advances have been made in water resource investigation due to the implementation of mathematical models, the development of theoretical frameworks, and the evaluation of sustainability indices. Together, they improve and make integrated water resource management more efficient. In this paper, in the study area of the Duero River Basin, located in Michoacan, Mexico, we schematize a series of numerical indices of the Watershed Governance Prism to determine the quantitative status of water governance in a watershed. The results, presented as axes, perspectives, and prisms in the Axis Index, Water Governance Index, and Watershed Governance Prism Index, provide the conclusion that it is possible to establish and evaluate the Watershed Governance Prism Index using our numerical implementation of the Watershed Governance Prism theoretical framework. Thus, it is possible to define a quantitative status and evoke how water governance is being designed and implemented in a watershed

Opinion: Urban Resilience Efforts Must Consider Social And Political Forces

Environmental disasters, ranging from catastrophic floods to extreme temperatures, have caused more than 30,000 deaths per year and more than US$ 250–300 billion a year in economic losses, globally, between 1995 and 2015. Improved infrastructure and planning for extreme events is essential in urban areas, where an increasingly greater fraction of the world’s inhabitants reside. In response, international governmental and private initiatives have placed the goal of resilience at the center stage of urban planning. [For example, The 100 Resilient Cities Initiative (www.100resilientcities.org/); the Global Covenant of Mayors (https://www.compactofmayors.org/globalcovenantofmayors/); and the recent UN Habitat III (https://habitat3.org/the-new-urban-agenda)]. In addition, scientific and policy communities alike now recognize the need for “safe-to-fail” infrastructural design, and the potential role of green and blue infrastructure in mediating hydrological and climatic risks in cities

Comparative study of enteric viruses, coliphages and indicator bacteria for evaluating water quality in a tropical high-altitude system

<p>Abstract</p> <p>Background</p> <p>Bacteria used as indicators for pathogenic microorganisms in water are not considered adequate as enteric virus indicators. Surface water from a tropical high-altitude system located in Mexico City that receives rainwater, treated and non-treated wastewater used for irrigation, and groundwater used for drinking, was studied.</p> <p>Methods</p> <p>The presence of enterovirus, rotavirus, astrovirus, coliphage, coliform bacteria, and enterococci was determined during annual cycles in 2001 and 2002. Enteric viruses in concentrated water samples were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Coliphages were detected using the double agar layer method. Bacteria analyses of the water samples were carried out by membrane filtration.</p> <p>Results</p> <p>The presence of viruses and bacteria in the water used for irrigation showed no relationship between current bacterial indicator detection and viral presence. Coliphages showed strong association with indicator bacteria and enterovirus, but weak association with other enteric viruses. Enterovirus and rotavirus showed significant seasonal differences in water used for irrigation, although this was not clear for astrovirus.</p> <p>Conclusion</p> <p>Coliphages proved to be adequate faecal pollution indicators for the irrigation water studied. Viral presence in this tropical high-altitude system showed a similar trend to data previously reported for temperate zones.</p

Improving Water Access and Health through Rainwater Harvesting: Perceptions of an Indigenous Community in Jalisco, Mexico

This article presents a mixed methods case study of an isolated indigenous community (the Wixaritari) in Jalisco state, Mexico, where the patterns of access to water have been changing due to Rainwater Harvesting Systems (RWHSs). The lack of water in this region is extremely precarious; women and children spend approximately one to three hours a day fetching water, and families live with less than 20 L per person/day. To better understand the relationship between water access and health derived from the use of RWHSs, we first analyzed epidemiological data (2014&ndash;2017) from cases of Acute Diarrheal Diseases (ADDs) and household water quality. Next, we surveyed households on water access after the introduction of RWHSs, including questions about perceptions of health problems associated with water. The results revealed that the introduction of RWHSs water access in this community has increased quantitatively and qualitatively and the incidence of ADDs has decreased significantly. However, the surveys and interviews indicate a disconnect between the incidence of ADDs and perceptions of health problems. We conclude that RWHSs can have tangible benefits, but they can be potentially undermined by perceptions of communities that have different understandings of the cause of disease

Adaptive pathways and coupled infrastructure: seven centuries of adaptation to water risk and the production of vulnerability in Mexico City

Infrastructure development is central to the processes that abate and produce vulnerabilities in cities. Urban actors, especially those with power and authority, perceive and interpret vulnerability and decide when and how to adapt. When city managers use infrastructure to reduce urban risk in the complex, interconnected city system, new fragilities are introduced because of inherent system feedbacks. We trace the interactions between system dynamics and decision-making processes over 700 years of Mexico City's adaptations to water risks, focusing on the decision cycles of public infrastructure providers (in this case, government authorities). We bring together two lenses in examining this history: robustness-vulnerability trade-offs to explain the evolution of systemic risk dynamics mediated by feedback control, and adaptation pathways to focus on the evolution of decision cycles that motivate significant infrastructure investments. Drawing from historical accounts, archeological evidence, and original research on water, engineering, and cultural history, we examine adaptation pathways of humans settlement, water supply, and flood risk. Mexico City's history reveals insights that expand the theory of coupled infrastructure and lessons salient to contemporary urban risk management: (1) adapting by spatially externalizing risks can backfire: as cities expand, such risks become endogenous; (2) over time, adaptation pathways initiated to address specific risks may begin to intersect, creating complex trade-offs in risk management; and (3) city authorities are agents of risk production: even in the face of new exogenous risks (climate change), acknowledging and managing risks produced endogenously may prove more adaptive. History demonstrates that the very best solutions today may present critical challenges for tomorrow, and that collectively people have far more agency in and influence over the complex systems we live in than is often acknowledged