Catchment contribution

Hg flux and watershed area, the relative importance of direct deposition and catchment contributions can be assessed. Such interpretations assume that lake sediments are stratigraphically and quantitatively reliable archives of Hg inputs to aquatic systems. 

Catchment Contributions. The slope of the regression lines in Figure 9 is the rate at which Hg is transported from the terrestrial catchment to the lake sediments (in units of micrograms of Hg per square meter of catchment per year). If one assumes that all of the Hg in the catchment is derived from the atmosphere, then the slope divided by the atmospheric deposition rate (the intercept) is the proportion of terrestrial Hg deposition that is transported to the lake. The slope will equal the rate of atmospheric deposition if the entire flux to the catchment is transported to the lake. On the other hand, the slope will equal zero—as observed for Pb by Dillon and Evans (18)—if direct deposition to the lake surface is the only significant source. 

Catchment acidification has been invoked to explain increases in the catchment contribution of Mn in Sweden (Renberg, 1985) and Fe in Norway (Davis et al., 1983). Enhanced supply of Al due to catchment acidification is also reported (White Gubala, 1990). The export of trace metals is demonstrated in acidified parts of Sweden, where stream water concentrations of Cd and Zn are enhanced in acidified areas (Johansson et al., 1995). In a study of catchment and lake budgets in the highly acidified area around Sudbury, Ontario, Dillon et al. (1988) found that the acidified catchments were sources for Al, Mn and Ni, but sinks for Cu and Zn. An enhanced supply from the catchment is supported by lake sediment studies for Al and Zn, but not for Pb. 

A recent review of research on phosphorus input to surface waters from agriculture highlights the variability of particulate and dissolved phosphorus contributions to catchments. The input varies with rainfall, fertilizer application rates, the history of the application of the fertilizer, land use, soil type, and between surface and sub-surface water. The balance struck between export of nutrients from the catchment and recipient-water productivity is the primary factor which controls its quality. 

Local assessment of the mass balance of the most critical PhCs (the most frequently administered antibiotics, analgesics/anti-inflammatories and the psychiatric dmg carbamazepine, considered an anthropogenic marker in wastewaters [121]) also provides useful information about the PhC contribution of the hospital effluent with respect to that of the catchment area. The extent of this contribution will differ between compound, but Beier et al. [92], in particular, reported that it can reach as high as 94% for some antibiotics (ciprofloxacin), although Kummerer [53], on the other hand, stated that only up to 25% of the antibiotics administered in Germany are used in hospitals. 

Small hospital in a densely populated catchment area evaluate the specific contribution of HWWs to the total WWTP influent, in particular, the most critical PhCs administrated in the health structure. Evaluate the technical and economic feasibility of adopting dedicated specific treatments for HWWs. Evaluate advantages and drawbacks of co-treatment. 

Small hospital in a small urban catchment area a local mass balance analysis of micro- and macropoUutant loads can provide useful information about the contribution of the different users. Environmental risk assessment of the expected final effluent and analysis of the characteristics of the local receiving water body will guide selection of the advanced treatment sequence (MBR, ozone, UV). 

In the Front Range of the Rocky Mountains, the N enrichment of alpine catchments from increased atmospheric N deposition from agricultural and urban development on the plains is an important environmental and resource issue (Williams et al., 1996). The difference in N content (about 0.5-1.0% for terrestrially derived DOM vs. about 2-3% for microbially derived DOM) could be significant in terms of estimating the contribution of dissolved fulvic acid flux to the yield of N from alpine and subalpine catchments in the Rocky Mountains. The example for this alpine catchment illustrates the potential usefulness of the fluorescence index in field studies addressing applied issues related to environmental management. 

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