Chemicals in river

Monitoring studies in the actual fields are not required because Japan has no provisional registration system. Most companies, however, have been voluntarily monitoring their chemicals in river water after distribution. 

Prediction or measurement of u is of paramount importance for assessing transport of chemicals in rivers. The following discussion will be restricted to the special case of stationary uniform flow. This means that at a fixed location the discharge Q is constant, the cross section A does not change in size or shape, and the surface slope remains constant. With these assumptions, an equilibrium between the gravitational... 

Viet, P.H., Hoai, P.M., Ha, N.P., Lieu, T.T., Dung, H.M., Tuyen, L.H., 2002. Distribution and behavior of endocrine disrupting chemicals in River and estuary environment from Vietnam. In Proceedings of the UNU International Symposium on Tracing Pollutants from Agrochemical Use Focus on EDC Pollution. Hanoi, Vietnam, April 15-16, 2002. 

GREAT-ER. 2005. A GIS assisted model for environmental risk assessment and management of chemicals in river basins, http //www.great-er.org/pages/home.cfm (accessed December 15, 2005). 

Dietrich, A.M., D.S. Millington, and Y.-H. Seo. 1988. Specific identification of synthetic organic chemicals in river water using liquid-liquid extraction and resin adsorption coupled with electron impact, chemical ionization and accurate mass measurement gas chromatography-mass spectrometry analysis. J. Chromatogr. 436 229-241. 

Mackay D., Paterson S.and Joy M. 1983b. A quantitative water, air, sediment interaction (QWASI) fugacity model for describing the fate of chemicals in rivers. Chemosphere 12 1193-1208. 

Their contribution to the total dissolved load in rivers can be estimated by considering the mean composition of river water and the relative importance of various rocks to weathering. Estimates (18) indicate that evaporites and carbonates contribute approximately 17% and 38%, respectively, of the total dissolved load in the wodd s rivers. The remaining 45% is the result of the weathering of siUcates, underlining the significant role of these minerals in the overall chemical denudation of the earth s surface. 

The paper describes the different chemical sensors and mathematical methods applied and presents the review of electronic tongue application for quantitative analysis (heavy metals and other impurities in river water, uranium in former mines, metal impurities in exhaust gases, ets) and for classification and taste determination of some beverages (coffee, bear, juice, wines), vegetable oil, milk, etc. [1]. 

Table 17-1 Composition and average concentrations of chemicals in seawater and Rhine River water (Duisburg)...

C. Aguilar, I. Feirer, R Bonnll, R. M. Marce and D. Barcelo, Monitoring of pesticides in river water based on samples previously stored in polymeric cartridges followed by on-line solid-phase extraction-liquid cliromatography-diode array detection and confirmation by atmospheric pressure chemical ionization mass spectrometry . Anal. Chim. Acta 386 237-248 (1999). 

D. Puig, L. Silgoner, M. Grasserbauer and D. Barcelo, Part-per-trillion level determination of priority methyl-, nirto-, and clilor ophenols in river water samples by automated online liquid/solid exrtaction followed by liquid chr omatography/mass spectr ometry using atmospheric pressure chemical ionization and ion spray interfaces . Anal. Chem. 69 2756-2761 (1997). 

The most stable minerals are often physically eroded before they have a chance to chemically decompose. Minerals that decompose contribute to the dissolved load in rivers, and their solid chemical-weathering products contribute to the secondary minerals in the solid load. The secondary minerals and the more stable primary minerals are the most important constituents of clastic sedimentary rocks. Consequently, the secondary minerals of one cycle of erosion are... 

There are two principal ways to selectively partition different elements between the dissolved and solid loads in rivers by selective chemical weathering of particular primary... 

Fig. 9-8 Histogram of dissolved solids of samples from the Orinoco and Amazon River basins and corresponding denudation rates for morpho-tectonic regions in the humid tropics of South America (Stal-lard, 1985). The approximate denudation scale is calculated as the product of dissolved solids concentrations, mean armual runoff (1 m/yr), and a correction factor to account for large ratios of suspended load in rivers that drain mountain belts and for the greater than average annual precipitation in the lowlands close to the equator. The correction factor was treated as a linear function of dissolved solids and ranged from 2 for the most dilute rivers (dissolved solids less than lOmg/L) to 4 for the most concentrated rivers (dissolved solids more than 1000 mg/L). Bedrock density is assumed to be 2.65 g/cm. (Reproduced with permission from R. F. Stallard (1988). Weathering and erosion in the humid tropics. In A. Lerman and M. Meybeck, Physical and Chemical Weathering in Geochemical Cycles," pp. 225-246, Kluwer Academic Publishers, Dordrecht, The Netherlands.)...

Polymeric precolumns of styrene-divinylbenzene were used by Aguilar et al. to monitor pesticides in river water. Water samples (50 mL) were trace enriched on-line followed by analysis using LC combined with diode-array detection. LC atmospheric pressure chemical ionization (APCI) MS was used for confirmatory purposes. It was found that after the pesticides had been extracted from the water sample, they could be stored on the precartridges for up to 3 months without any detectable degradation. This work illustrates an advantage of SPE for water samples. Many pesticides which may not be stable when stored in water, even at low temperature, may be extracted and/or enriched on SPE media and stored under freezer conditions with no detectable degradation. This provides an excellent way to store samples for later analysis. 

The role of radionuclides as tracer of the chemical transport in river is also reinforced by the fact that each of the U-Th-Ra elements has several isotopes of very different half-lives belonging to the U-Th radioactive series. Thus, these series permit comparison of the behavior of isotopes of the same element which are supposed to have the same chemical properties, but very different lifetimes. These comparisons should be very helpful in constraining time scales of transport in rivers. This was illustrated by Porcelli et al. (2001) who compared ( " Th/ U) and ( °Th/ U) ratios in Kalix river waters and estimated a transit time for Th of 15 10 days in this watershed. The development of such studies in the future should lead to an important progress in understanding and quantifying of transport parameters in surface waters. This information could be crucial for a correct use of U-series radioactive disequilibria measured in river waters to establish weathering budgets at the scale of a watershed. 

Understanding the behavior of radionuclides in estuaries, as the dynamic interface between the continental hydrochemical systems and the ocean basins, requires consideration of broader chemical cycling in the hydrosphere. In this volume, the behavior of U- and Th-series isotopes in rivers is discussed by Chabaux et al. (2003), that in groundwaters by Porcelli and Swarzenski (2003), and that in oceans by Cochran and Masque (2003). General background information is provided by Bourdon et al. (2003). 

River inputs. The riverine endmember is most often highly variable. Fluctuations of the chemical signature of river water discharging into an estuary are clearly critical to determine the effects of estuarine mixing. The characteristics of U- and Th-series nuclides in rivers are reviewed most recently by Chabaux et al. (2003). Important factors include the major element composition, the characteristics and concentrations of particular constituents that can complex or adsorb U- and Th-series nuclides, such as organic ligands, particles or colloids. River flow rates clearly will also have an effect on the rates and patterns of mixing in the estuary (Ponter et al. 1990 Shiller and Boyle 1991). 

Sheldon LS, Hites RA. 1979. Sources and movement of organic chemicals in the Delaware River. Environmental Science and Technology 13 574-579. 

The Qwasi model estimate the fate of a chemical in a water system (lake, river, etc.) consisting of water, bottom and suspended sediments, and air. The model is... 

The waste pathway and river modelling module is used for the prediction of chemical emission, of chemical removal/transformation during conveyance and treatment, and of chemical fate in rivers [62]. Chemical fate in wastewater treatment plants (WWTP) and in rivers is described deterministically, with several levels of complexity being available to reflect the available information concerning both the chemical and the environment. 

QWASI, the Quantitative Water, Air Sediment Interaction model by Mackay et al. [14] is a fugacity III model (Version 3.10, 2007) and it describes the fate of chemicals in aquatic systems, depending on direct discharge, inflow in rivers, and atmospheric deposition. Hence, this model addresses the local scale, as does the 2-FUN Tool. 

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