Water test case, river

The results of the river water and seawater test cases computed by the aqueous models listed in Table I are summarized in Tables IV-X. Tables IV and V compare selected major and minor species computed for the river water test case, and Tables VI and VII make a similar comparison for the seawater test case. Table VIII compares activity coefficients computed for the major species in seawater and Table IX and X tabulate saturation indices for selected minerals in the river water and seawater test... 

Table IV -Log Molality, of Selected Major Species in River Water Test Case GO...

Saturation Index for Selected Minerals in River Water Test Case... 

Ba, Sr, and B. Consistency between programs was evaluated by comparing the log of the molal concentrations of free ions and complexes for two test solutions a hypothetical seawater analysis and a hypothetical river water analysis. Comparison of the free major ion concentrations in the river water test case shows excellent agreement for the major species. In the seawater test case there is less agreement and for both test cases the minor species commonly show orders of magnitude differences in concentrations. These differences primarily reflect differences in the thermodynamic data base of each chemical model although other factors such as activity coefficient calculations, redox assumptions, temperature corrections, alkalinity corrections and the number of complexes used all have an affect on the output. 

One approach to determine the reliability of geochemical codes is to take well-defined input data and compare the output from several different codes. For comparison of speciation results, Nordstrom et al. (1979) compiled a seawater test case and a river-water test case, i.e., seawater and river-water analyses that were used as input to 14 different codes. TTie results were compared and contrasted, demonstrating that the thermodynamic databases, the number of ion pairs and complexes, the form of the activity coefficients, the assumptions made for redox species, and the assumptions made for equilibrium solubilities of mineral phases were prominent factors in the results. Additional arsenic, selenium, and uranium redox test cases were designed for testing of... 

Collectively, the programs mentioned above represent the "state of the art" in the calculation of the equilibrium distribution of species in aqueous systems. As a means of examining the consistency of these programs, two test cases (a dilute river water and an average seawater analysis) were compiled and mailed to more than fifty researchers who have been active in the field of chemical modeling. These test cases may overlook many of the features of specific programs, but they provide a common basis by which most of the programs can be... 

Navarro E, Guasch H, Sabater S (2002) Use of microbenthic algal communities in ecotoxico-logical tests for the assessment of water quality the Ter river case study. J Appl Phycol 14 41... 

Organic concentrates of water samples from the Rhine River and Meuse River were tested for toxicity by using a 48-h mortality test on fish (Poecilla reticulata) at 3-month intervals for 1 year (11). The river samples were concentrated by adsorption on XAD followed by elution with acetone. Rhine water samples were more toxic than Meuse water samples in most cases (7,12, 13) (see Figure 6). 

Heavy metals and hypochlorite can both inhibit AChE [33] and so similar tests for pesticides were repeated in solutions containing either 20mgl 1 Hg2"1" or 0.1mgl 1 NaC104. In both cases, large inhibition effects were noted for both the enzyme electrodes, not just the mutant, so indicating the presence of a non-specific interferent. When river water was introduced to the system, no inhibition effects were observed, however, when omethoate spiked river water samples were used, then inhibition effects could be measured for the mutant with similar levels of sensitivity to when pure water was used as the matrix. 

Biodegradation studies may use either pure or mixed cultures of microorganisms. Pure cultures can be obtained either from culture collections or by enrichment from natural samples (sewage, soil, river water, etc.). In the latter case, cultures usually are isolated by serial transfer in media containing the test chemical as the sole carbon source. 

Surface water estimated t/2 = 9.9-32 d in surface waters at various locations in case of a first order reduction process t/2 = 3-30 d in rivers, t,/2 = 30-300 d in lakes and ground waters (Zoeteman et al. 1980) t,/2 = 25 d in spring at 8-16°C, 14 d in summer at 20-22°C and 12 d in winter at 3-7°C when volatilization dominates, and t/2 = 12.1 d and 12.0 d for experiments with and without HgCl2 as poison respectively in September 9-15 in marine mesocosm (Wakeham et al. 1983) t,/2 = 4320-8640 h, based on aerobic river die-away test data (Mudder 1981 quoted, Howard et al. 1991) and saltwater sample grab data (Jensen Rosenberg 1975 quoted, Howard et al. 1991) calculated t/2 = 10 d and 32 d concentration reduction between sampling points on the Rhine River and a lake in the Rhine basin, respectively (Zoeteman et al. 1980 quoted, Howard 1990) t,/2(aerobic) = 180 d, t/2(anaerobic) = 98 d in natural waters (Capel Larson 1995). 

Let us use an example to illustrate how the ANOVA calculations are performed on some test data. A chemist wishes to evaluate four different extraction procedures that can be used to determine an organic compound in river water (the quantitative determination is obtained using ultraviolet [UV] absorbance spectroscopy). To achieve this goal, the analyst will prepare a test solution of the organic compound in river water and will perform each of the four different extraction procedures in replicate. In this case, there are three replicates for each extraction procedure. The quantitative data is shown below. 

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