SGU network for groundwater chemistry

Since the late 1960s, the Swedish Geological Survey (SGU) has operated a groundwater network comprising about 400 wells throughout Sweden. The groundwater level is measured twice per month, resulting in maps (published monthly) of the groundwater situation in the country (Table 6, #7.1). Chemical analyses are performed twice per year in 30 wells selected from the network (Table 6, #7.2). The groundwater sampling network for water quality called “reference stations – groundwater” is split in two parts: one called trend stations (comprised of 80 stations that are sampled a couple of times per year) and the other called periodical stations (comprised of a large number of stations sampled once every 6 years). In total, 528 stations are sampled every 6 years, most of which are natural springs and the rest are groundwater observational wells and municipal water supplies (Table 4, #7.1). Half of the trend stations are situated in small aquifers, e.g. till deposits, while the other half are situated in large aquifers such as sand and gravel deposits in eskers and fossil deltas. Groundwater from all stations is analyzed according to a base program. In addition, complementary analyses are performed for a number of trace elements (Cu, Zn, Pb, Cd, Cr, Ni, Co, As, V and in some cases Hg). SGU operates a network for groundwater comprising about 400 stations for groundwater level and 30 stations for groundwater quality. This network is financed by SGU and data are not freely available. SGU also operates a environmental monitoring network for groundwater comprising 80 trend stations visited a couple of times per year and 528 periodical stations that are only visited oncce per six years. This monitoring network is financed by SEPA and data can be downloaded from SGU hompage. Water from the reference stations are analyzed for the following chemistry: All stations: Temperature, pH, PO4-P, Tot-P, conductivity (EC), NH4-N, NO3-N, NO2-N, Tot-N, TOC, F, Cl, Alk/Ac, SO4, Ca, Mg, Na, K, Fe, Mn, Si and Al Further analysis for periodical stations are the following metals Cu, Zn, Pb, Cd, Cr, Ni, Co, As, V and Hg and the organic compounds trichloretylen, tetrachloretylen