scholarly journals Formation of NDMA by Chloramination of Nitrogenous Pharmaceuticals

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
J. Le Roux ◽  
H. Gallard ◽  
J.P. Croué
Keyword(s):  
Structural Characteristics ◽  
Haloacetic Acids ◽  
Formation Mechanisms ◽  
Tertiary Amines ◽  
Human Carcinogen ◽  
Conversion Rates ◽  
Water Chlorination ◽  
By Products ◽  
New Formation

Many disinfection by-products (DBPs) are formed during water chlorination, including trihalomethanes (THMs) and haloacetic acids (HAAs). Disinfection with chloramines is often used to reduce the production of regulated DBPs. However, chloramination can lead to the formation of N–nitrosamines, including N–nitrosodimethylamine (NDMA), a probable human carcinogen. The formation mechanisms of NDMA are not fully understood. Proposed mechanisms used dimethylamine (DMA) as a model precursor, but results show that certain widely used tertiary dimethylamines (e.g. the pharmaceutical ranitidine) show much higher conversion rates to NDMA than DMA. These amounts of NDMA cannot be explained by current proposed mechanisms. New formation mechanisms have to be proposed to explain the importance of structural characteristics of tertiary amines for NDMA formation.

Formation of By-products in Pure and Aqueous Acrylic Acid - Kinetic Measurements and Formation Mechanisms

2017 ◽  
Vol 40 (4) ◽  
pp. 755-759
Author(s):  
Christian A. Pfeifer ◽  
Cordula Scholz ◽  
Kevin Vogel ◽  
Alfons Drochner ◽  
Herbert Vogel
Keyword(s):  
Acrylic Acid ◽  
Formation Mechanisms ◽  
Kinetic Measurements ◽  
By Products

scholarly journals Formation of DBPs in the drinking eater of Athens, Greece: a Ten-Year study

2013 ◽  
Vol 7 (1) ◽  
pp. 106-118
Keyword(s):  
European Union ◽  
Drinking Water ◽  
Water Treatment ◽  
Chloral Hydrate ◽  
Haloacetic Acids ◽  
The European Union ◽  
Water Treatment Plants ◽  
Naturally Occurring ◽  
By Products ◽  
The Eu

The formation of Disinfection By-Products (DBPs) in drinking water results from the reaction of chlorine or other disinfectants added to the water with naturally occurring organic materials, and has raised concerns during the last decades because these compounds are harmful for human health. During the present work, the formation of different categories of DBPs was investigated in four water treatment plants (WTP) using chlorine as disinfectant, and in selected points of the distribution network of Athens, Greece, which is supplied from these four WTP, during a period of ten years. The concentrations of DBPs were generally low and the annual mean concentrations always well below the regulatory limit of the European Union (EU) for the total trihalomethanes (TTHMs). The haloacetic acids (HAAs) have not been regulated in the EU, but during this investigation they often occurred in significant levels, sometimes exceeding the levels of TTHMs, which highlights the importance of their monitoring in drinking water. Apart from THMs and HAAs, several other DBPs species were detected at much lower concentrations in the chlorinated waters: chloral hydrate, haloketones and, in a limited number of cases, haloacetonitriles.

scholarly journals Sporadic Ca and Ca<sup>+</sup> layers at mid-latitudes: Simultaneous observations and implications for their formation

2001 ◽  
Vol 19 (1) ◽  
pp. 47-58 ◽  
Author(s):  
M. Gerding ◽  
M. Alpers ◽  
J. Höffner ◽  
U. von Zahn
Keyword(s):  
Seasonal Variation ◽  
Lower Thermosphere ◽  
Simultaneous Occurrence ◽  
Formation Mechanisms ◽  
Ion Chemistry ◽  
Significant Seasonal Variation ◽  
Ca Ions ◽  
Ion Chemistry And Composition ◽  
Metal Layers ◽  
New Formation

Abstract. We report on the observations of 188 sporadic layers of either Ca atoms and/or Ca ions that we have observed during 112 nights of lidar soundings of Ca, and 58 nights of Ca+ soundings, at Kühlungsborn, Germany (54° N, 12° E). The Ca+ soundings have been performed simultaneously and in a common volume with the Ca soundings by two separate lidars. Correlations between sporadic neutral and ionized metal layers are demonstrated through four case studies. A systematic study of the variations of occurrence of sporadic Ca and Ca+ layers reveals that neutral and ionized Ca layers are not as closely correlated as expected earlier: (a) The altitude distribution shows the simultaneous occurrence of both sporadic Ca and Ca+ layers to be most likely only in the narrow altitude range between 90 and 95 km. Above that region, in the lower thermosphere, the sporadic ion layers are much more frequent than atom layers. Below 90 km only very few sporadic layers have been observed; (b) The seasonal variation of sporadic Ca layers exhibits a minimum of occurrence in summer, while sporadic Ca+ layers do not show a significant seasonal variation (only the dense Ca+ layers appear to have a maximum in summer). At mid-latitudes sporadic Ca layers are more frequent than sporadic layers of other atmospheric metals like Na or K. For the explanation of our observations new formation mechanisms are discussed.Key words. Ionosphere (ion chemistry and composition; ionosphere-atmosphere interactions; mid-latitude ionosphere)

scholarly journals Exposure to Drinking Water Chlorination by-Products and Fetal Growth and Prematurity: A Nationwide Register-Based Prospective Study

2020 ◽  
Vol 128 (5) ◽  
pp. 057006
Author(s):  
Melle Säve-Söderbergh ◽  
Jonas Toljander ◽  
Carolina Donat-Vargas ◽  
Marika Berglund ◽  
Agneta Åkesson
Keyword(s):  
Drinking Water ◽  
Prospective Study ◽  
Fetal Growth ◽  
Water Chlorination ◽  
By Products

Variations of DBPs precursors according to location within the distribution system

2009 ◽  
Vol 9 (4) ◽  
pp. 413-421
Author(s):  
C. Beaulieu ◽  
M. J. Rodriguez ◽  
J.-B. Sérodes
Keyword(s):  
Organic Matter ◽  
Water Treatment ◽  
Distribution System ◽  
Water Distribution ◽  
Water Distribution System ◽  
Spatial Behavior ◽  
Haloacetic Acids ◽  
Formation Potential ◽  
The Impact ◽  
By Products

Little information is available on the evolution of remaining organic matter (ROM) in a water distribution system (WDS) and its impact on the generation of disinfection by-products (DBPs). This research involves the characterization, through sample fractionation processes and experimental chlorination tests, of the reactivity of DBP precursors occurring within a WDS. The study is based on samples collected in various locations of a WDS during a complete year. For each sample, six fractions were generated to determine their potential for formation of trihalomethanes (THMs) and haloacetic acids (HAAs). Fractionation processes on ROM demonstrated that the spatial behavior of precursors for THMs differs from that for precursors of HAAs. In addition, experimental chlorination tests showed that the reactivity of the investigated fractions, in terms of DBP formation potential (DBPfp), was different from each other according to location in the WDS. DBPfp for the studied fractions changed drastically during water treatment. However, changes of DBPfp for fractions were relatively low between the beginning and the extremity of the distribution system. Since the results of this research confirm that the ability to produce DBPs is related to the nature of the fractions, they could be useful to evaluate the impact of re-chlorination on DBP formation in a WDS.

Water Chlorination By-Products and Congenital Anomalies in England and Wales

Epidemiology ◽  
2007 ◽  
Vol 18 (Suppl) ◽  
pp. S86
Author(s):  
M Nieuwenhuijsen ◽  
Abramsky Lenore ◽  
B Patr ◽  
M Toledano ◽  
N Best ◽  
...  
Keyword(s):  
Congenital Anomalies ◽  
England And Wales ◽  
Water Chlorination ◽  
By Products
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