National Long-Term Surveillance of Swiss Rivers
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Verh. Internat. Verein. Limnol. 28 1101–1106 Stuttgart, July 2002 National long-term surveillance of Swiss rivers A. Jakob, E. Binderheim-Bankay and J. S. Davis Introduction Rhine (IKSR), the Global Environment Monitoring System – United Nations Environment Pro- The “National Long-term Surveillance of Swiss Riv- gram/World Health Organization (GEMS- ers” (NADUF) programme was initiated in 1972 as UNEP/WHO)). a cooperative project between three institutes: the The NADUF network of sampling stations Swiss Agency for the Environment, Forests and includes locations on all the major rivers of Switzer- Landscape (BUWAL), the Swiss Federal Institute for land. Chemical–physical data are collected at 19 sta- Environmental Science and Technology (EAWAG) tions (Fig. 1) selected to provide a representative and the Federal Office for Water and Geology overview of Swiss rivers. The locations include all (BWG). The program conducts the surveillance and rivers flowing out of Switzerland, the main tributar- evaluation of the chemical–physical state of Swiss ies to major lakes, and catchment areas at a range of rivers. altitudes extending from the Alps to the Swiss Pla- The goals of NADUF serve both national and teau. In addition, several heavily polluted river sec- international interests. The main national goal is to tions, of particular interest in water protection evaluate the effectiveness of water protection mea- efforts, are also sampled. The sampling modes sures. In addition, NADUF provides both basic data employed depend on the parameter group. Selected and sampling facilities for scientific studies on issues physical parameters are continuously measured with associated with river water. At the international level, electrodes. These parameters are: water level, tem- several NADUF stations serve as reference stations perature, electrical conductivity, pH and oxygen for other water surveillance programs (e.g. the Inter- concentration. Chemical parameters are measured national Commission for the Protection of the over 14-day periods, in samples continuously col- Fig. 1. Locations of sampling stations of the NADUF program. 0368-0770/02/0028-1101 $ 1.50 ©2002 E. Schweizerbart’sche Verlagsbuchhandlung, D-70176 Stuttgart A. Jakob et al., Long-term surveillance of Swiss rivers 1102 lected on a discharge-proportional basis (BINDER- 1993, based on subsidies for specified ecological HEIM-BANKAY et al. 2000). These parameters include measures, defined in the agricultural law. total hardness, carbonate hardness, total suspended solids, calcium, potassium, sodium, magnesium, sul- The on-going reduction of water pollution, phate, silicic acid, chloride, ortho-phosphate, total based on the increase of infrastructure serving phosphorus, nitrate, total nitrogen, dissolved organic wastewater collection and treatment, could be carbon, total organic carbon, lead, copper, zinc, cad- documented by the NADUF data. The major mium, chromium and nickel. Since the beginning of contribution to this reduction had however NADUF, all chemical parameters have been mea- taken place before the initiation of the NADUF sured in the same laboratory, thus enabling a consis- project – 60% of the population was already tency in the data series. Though the basic set of parameters is given, there are degrees of flexibility for connected to wastewater treatment plants at the the sampling program: the length of the measuring time the program started. period and additional parameter possibilities are The positive effects of the measures men- determined individually for each station; these can tioned above are described below for two be adapted to special data needs for particular water NADUF stations. One station, Rhine at Basle, protection issues or for scientific research. represents a very large catchment area, on one of Europe’s largest rivers. The other station, Evaluating water protection measures at a Glatt at Rheinsfelden, represents a minor tribu- national level tary to the Rhine, north of Zurich. The Glatt, The NADUF databank, comprising almost 30 being heavily polluted at this location, is thus a years of surveillance in an extensive network of critical point to examine, and one at which the sampling stations, is an exceptional source of effects of water protection measures are readily information on the development of river water recognizable. The data obtained at these sta- quality throughout Switzerland. Evaluations tions are plotted in two different types of highlight a positive trend in the quality: with graphs. One represents a qualitative view, show- the exception of only a few rivers showing ing the development of the concentrations of marked pollution, all the main rivers in Switzer- the selected parameters. The other represents a land meet the criteria set by the water protec- quantitative view, in that the annual averages of tion ordinance. This can be seen as a successful the concentrations are shown in relation to the result of major endeavours for water protection respective annual discharges (JAKOB et al. 1994). that were undertaken throughout the country. Since concentration is influenced by discharge, In addition to documenting this general trend, a data evaluation looking at possible changes in the continuous surveillance program has been the amount of pollution benefits from compar- an effective instrument for the evaluation of ing concentrations occurring at similar those water protection measures that were initi- amounts of discharge. Using these evaluation ated during the course of investigation. For criteria, the following has been observed at the example, data evaluations clearly indicated a two stations: general decrease in phosphate. This arose from • The phosphate concentrations have signifi- the implementation of phosphate removal in cantly decreased since 1986. This is evident wastewater treatment plants, and from the both in graphs showing the development phosphate-ban initiated in 1986. In addition to along the time course (Fig. 2a, b), as well as such measures, which were implemented to in the discharge-related diagram (Fig. 3a, b). specifically benefit water, it could be seen that This trend is mainly due to the phosphate some additional measures, aimed at other envi- ban, together with the expanded capacity of ronmental problems, also led to benefits for wastewater treatment plants, and the water quality. Among documented cases of such increased infrastructure, connecting homes benefits were the use of the catalytic converter, and businesses to the treatment plants. The as of 1985, which led to a reduction in the use reduction in phosphate concentration was of leaded gasoline and reductions in nitrogen; ca. 50% on the Rhine at Basle, and ca. 80% financial support for organic farming, as of on the Glatt at Rheinsfelden. 1103 Verh. Internat. Verein. Limnol. 28 (2002) 2.0 0.3 Glatt a) Rhine b) Phosphate-ban for detergence Phosphate-ban for detergence 1986 1986 [mg P/l) 1.5 [mg P/l) 0.2 1.0 0.1 0.5 0.0 0.0 77 79 81 83 85 87 89 91 93 95 97 99 77 79 81 83 85 87 89 91 93 95 97 99 20 4.0 18 Glatt c) Rhine d) reduction of nitrous oxide emissions 16 [mg N/l) µg Pb/l) [ 3.0 of motorised traffic 14 12 10 2.0 8 6 1.0 4 2 new agricultural law 1993 0 0.0 77 79 81 83 85 87 89 91 93 95 97 99 77 79 81 83 85 87 89 91 93 95 97 99 Fig. 2. Development of phosphate and nitrate concentrations in the Rhine at Basle (b and d) and of phos- phate and lead concentrations in the Glatt at Rheinsfelden (a and c). The thin line represents the 14-day continuously collected, discharge-proportional samples. The thicker line shows the discharge weighted annual averages. The phosphate ban had an immediate influence on the phosphate concentration in water; in contrast, the reduced lead and nitrogen emissions from motorised traffic have only gradually influenced the concentrations of these substances in water. • The lead concentrations have decreased sig- The development of the nitrate concentration nificantly since 1989. This is seen both in shows an increasing trend through the 1980s the graph representing the development of and a decreasing trend during the 1990s. The concentration over time (Fig. 2c), and in the maxima occurred between 1986 and 1993 discharge related graph (Fig. 3c). This (Fig. 2d). The same pattern is seen in the dis- reduction is considered the result of the charge related graph (Fig. 3d). These changes decrease in use of leaded gasoline, an effect are possibly due to the intensification in agri- stemming from the introduction of catalytic cultural methods before 1993, followed by the converters. According to the BUWAL adoption of measures furthering a more ecolog- (1997), the lead emission from traffic ically oriented agriculture. There is however decreased ca. 90% between the early 1970s most likely an additional factor contributing to and 1996. The reduction in lead concentra- the decrease in nitrate in water: as of the late tion is particularly marked in the Glatt, 1980s there has been a decrease in nitrogen reflecting the high proportion (24%) of emissions from vehicles. This resulted in densely populated land in the catchment reduced deposition, and thus a lower nitrate area. loading of waters. According to information A. Jakob et al., Long-term surveillance of Swiss rivers 1104 0.12 [mg P/l] Glatt a)[mg P/l] Rhine b) 0.8 77 79 80 77 0.10 82 79 78 81 85 83 80 0.6 83 81 0.08 84 85 82 84 86 0.06 0.4 91 90 86 92 88 87 0.04 89 93 94 0.2 89 88 96 96 9890 0.02 98 95 87 95 97 91 92 94 99 97 0.0 93 0.00 56789101112800 900 1000 1100 1200 1300 1400 1500 average discharge [m³/s] average discharge [m³/s] 7 1.9 [µg Pb/l] Glatt c)[mg N/l] Rhine d) 89 92 6 88 1.8 90 88 85 91 86 79 1.7 5 77 93 86 89 94 1.6 87 87 96 84 4 80 81 92 1.5 82 85 83 95 95 3 84 79 1.4 97 98 83 77 91 82 97 93 94 78 2 1.3 80 96 99 81 98 1 1.2 56789101112800 900 1000 1100 1200 1300 1400 1500 average discharge [m³/s] average discharge [m³/s] Fig.