Safe Drinking Water-A Local Example of a Global Challenge
Notice bibliographique
Résumé
INTRODUCTION Over the past 20 years water demands have steadily increased and the controversies and conflicts over drinking water are now a foremost concern of the public. The rapid shift by urban consumers towards the consumption of bottled water rather than drinking tap water suggests that the public has lost confidence in the safety of their water supplies. The Walkerton, Ontario incident, where 7 people died and over 2300 were hospitalized because E-coli found its way into the community drinking water supply system, made the public aware that even in Canada it is possible to contaminate drinking water sources when management is inadequate and when protective measures fail to be enforced. The incident in Walkerton occurred in May 2000 and was caused by a combination of physical, environmental and human factors. First, the water well was shallow ( Managing drinking water is a complex process and there is often no consensus on what measures best protect water supplies. Everybody seems to have an opinion on this issue but there is generally a lack of knowledge and understanding of requirements to provide safe drinking water. It can be stated that there is no absolutely safe way of protecting drinking water for everybody at all times. Water is a cyclic resource, moving through the hydrologic cycle. Water in the form of precipitation is naturally acidic and is more or less in equilibrium with carbon dioxide (carbonic acid). Natural precipitation reacts with vegetation and soil as it enters and flows through the canopy and soil matrix. If not lost through evapotranspiration, water moves laterally and vertically and in humid areas becomes groundwater or moves directly into streams and lakes. During this journey water dissolves minerals (nutrients) as it interacts with soils, vegetation, and the atmosphere and is also impacted by all land use activities. If conditions are appropriate, water may be charged with excess minerals or contaminants from human activities. Water with dissolved minerals is an ideal substance for biological and microbial growth. Thus one of the most challenging problems is microbial contamination and growth that can occur at the source or anywhere within the hydrological cycle or water delivery system. In the past we relied on chlorine as the most effective treatment method for bacterial contamination. This treatment has been questioned as being insufficient to deal with many viruses and protozoan (such as giaridia and cryptosporidium), and at the same time some people claim that chlorine itself poses a health hazard. As a result of this concern, a multi-barrier approach is being advocated. This is a system approach that attempts to identify all sources of contamination in a watershed context. Sources are identified and corrective measures can then be taken that range from source control and creation of absorptive buffer zones, to water treatment, including ozonation, ultraviolet treatment and filtration through sand and membrane filters. …
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,002 |
| Études des sciences et des technologies | 0,005 | 0,005 |
| Communication savante | 0,004 | 0,004 |
| Science ouverte | 0,001 | 0,008 |
| Intégrité de la recherche | 0,003 | 0,003 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,018 | 0,002 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».