Study of wetland water quality

Waters from wetlands and lakes may have relatively high concentrations of NOM. A study of surface water quality of wetland has been carried out on one of the Seine estuary, the Hode Marsh. This littoral wetland is located on the northern part of the Seine floodplain in France. 

UV spectra of the different samples, taken in summer 2000, are shown on Fig. 13, and the results of physico-chemical parameters are given in Table 2. The results obviously confirm the great difference of water quality between seawater and freshwater. 

According to the shape of UV spectra and physico-chemical results, different types of waters can be identified. The northern part of the marsh (wet meadows, stations 5 and 6) is only influenced by freshwaters. UV spectra are typical of natural water without organic matter (the absorbance above 240 nm is close to zero). The Gaussian shape around 210 nm indicates the presence of nitrates. UV spectra are superposed, meaning that water quality is the same for these two stations. The conductivity value of 420 pSIcm shows the direct influence of the chalk aquifer. 

Sample 4 presents a low concentration of organic matter, giving a residual absorbance on the entire spectrum, except for the shortest wavelengths related to the presence of chloride, the mouth of the canal directly opening into the Channel. This direct influence of salt water explains the high value of conductivity. 

UV spectra of samples 1 and 2, similar and superposed, are characteristic of water containing natural organic matter. The diffuse absorbance on the entire spectral domain 

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