Characteristics of suspended sediment in the upper rhone river, switzerland, including the particulate forms of phosphorus

Abstract

Six stations along the Upper Rhone River above Lake Geneva were sampled by continuous flow centrifuge for recovery of suspended sediment. The samples were taken four times, once in 1982 and three times in 1983. In addition the mouth of the river was sampled in a like manner every two weeks during 1982 until August 1983. Samples were analysed for the major elements SO,, A1,0,, K,O, MgO, Na,O, CaO, and Fe,O,; for trace elements, Zn, Cu, Ni, Mn, and Cr; for Org. C and Kjeldahl N; and the forms of phosphorus bound as Organic P (OP), Apatite P (AP), and Non Apatite Inorganic P (NAIP). The major elements and trace metals confirmed that there is virtually no change in the major geochemical characteristics of the suspended solids in the Rhone, spatially or temporally, indicating that this river is a well-mixed sedimentary system. AP also remained consistent in concentration throughout the year. Sediment recovered during the winter low flow, low turbidity period has been designated SED 1 whereas sediment from the high flow, high turbidity summer condition of the river has been designated SED 2. Org C, OP, and NAIP show a dramatic decrease in concentration from SED 1 to SED 2. The decline is ascribed to dilution of a relatively constant supply of organic matter and phosphorus derived mainly from point source sewage treatment plants to the Rhone. This results in variable partitioning of the OP/NAIP and Org C under the different turbidity condition in the river between winter and summer. This interpretation is confirmed by a low and consistent C-N ratio which except for March remains below 10. Higher values in March may be indicative of soil erosion during spring melt in the agricultural lands of the Rhone Valley. The estimated proportion of particulate bio-available phosphorus is 14 per cent for SED 1 and 7 per cent for SED 2. These low values would suggest that there would be no observable direct effect on the primary production of the receiving waters of Lake Geneva, which would thus respond only to the cumulative loading of phosphorus from the Rhone River.

Spatio-temporal distribution of organic and inorganic pollutants from Lake Geneva (Switzerland) reveals strong interacting effects of sewage treatment plant and eutrophication on microbial abundance

“…The supernatant was mineralised for 45 min at 130°C after addition of K 2 S 2 O 8 solution (5%). The P concentration was performed by measuring the absorbance of the blue complex obtained after reduction of molybdophosphoric acid according to the method described by Murphy and Riley (1962), Harwood et al (1969) and Burrus et al (1990).…”

Influence of Freshwater Sediment Characteristics on Persistence of Fecal Indicator Bacteria

“…Total nitrogen and ammonium concentrations in the sediments were measured by using the method of Kjeldhal (1883). Total phosphorus and its different forms were determined following the fractionation scheme of Williams et al (1976) as modified by Burrus et al (1990). Sediment characteristics were measured before and at the end of the experimentation.…”

Sequential extraction procedures for the determination of phosphorus forms in sediment

“…It was also shown that a substantial amount of calcium-bound P was solubilized by the citrate dithionite bicarbonate (CDB) reagent of Williams (1971Williams ( , 1976, for which the strongly chelating citrate ion was responsible. The CDB extraction was omitted by Burrus et al (1990), but the name of the modified procedure was not changed and usually listed as a later version of the Williams scheme (Golterman, 1996;Ruban et al, 1999b;Hoyle, 2004). The reason for this change was the belief that P extracted by NaOH reflects the P available to algae.…”

“…Total P (TP) and molybdate reactive P were measured in the pooled extracts and OP calculated from the difference (Williams et al, 1976). The extraction scheme of Williams as modified by Burrus et al (1990) is not completely sequential, involving two independent procedures. …”

“…The Williams (1976Williams ( , 1990) method was originally developed by modifying the Chang and Jackson soil P extraction scheme and applied to lake sediments. This method gives better results for siliceous sediments and the non-apatite P extracted by NaOH can be considered as bioavailable though it often leads to overestimates (Williams et al, 1976;Burrus et al, 1990). This method is not suitable to be used in calcareous sediments because of re-adsorption by carbonates (Hieltjes and Lijklema, 1980;Golterman, 1996;Pettersson et al, 1988).…”