Under field conditions modern digital conductivity meters give standardized, rapid and reproducible measurements. Here we investigate the accuracy of their estimates of the composition of karst waters, as total hardness (TH, as mg/L CaCO 3 ) for limestone and dolomite. These are the fundamental measures of process in carbonate karst geomorphology. PHREEQC theoretical curves for the dissolution of pure calcite/aragonite and dolomite in water at 25°C are compared with water analyses from karst studies worldwide. Other principal ions encountered are sulphates, nitrates and chlorides (the 'SNC' group). From carbonate karsts, 2309 spring, well and stream samples were divided into uncontaminated (SNC < < < < < 10%), moderately contaminated (10 < < < < < SNC < < < < < 20%), and contaminated (SNC > > > > > 20%) classes. Where specific conductivity (SpC) is less than 600 µ µ µ µ µS/cm, a clear statistical distinction can be drawn between waters having little contamination and substantially contaminated waters with SNC > > > > > 20%. As sometimes claimed in manufacturers' literature, in 'clean' limestone waters TH is close to 1 /2SpC, with a standard error of 2-3 mg/L. The slope of the best-fit line for 1949 samples covering all SNC classes where SpC < < < < < 600 µ µ µ µ µS/cm is 1·86, very close to the 1·88 obtained for clean limestone waters; however, the value of the intercept is ten times higher. The regression line for clean limestone waters where SpC > > > > > 600 µ µ µ µ µS/cm helps to distinguish polluted waters from clean waters with possible endogenic sources of CO 2 . In the range 250 < < < < < SpC < < < < < 600 µ µ µ µ µS/cm, dolomite waters can be readily distinguished from limestone waters.
The Fuglebekken basin is situated in the southern part of the island of Spitsbergen (Norwegian Arctic), on the Hornsund fjord (Wedel Jarlsberg Land). Surface water was collected from 24 tributaries (B1–B24) and from the main stream water in the Fuglebekken basin (25) between 10 July 2009 and 30 July 2009. The present investigation reveals the results of the analysis of these samples for their PAH and PCB content. Twelve of 16 PAHs and seven PCBs were determined in the surface waters from 24 tributaries and the main stream. Total PAH and PCB concentrations in the surface waters ranged from 4 to 600 ng/L and from 2 to 400 ng/L respectively. The highest concentrations of an individual PCB (138–308 ng/L and 123 ng/L) were found in samples from tributaries B9 and B5. The presence in the basin (thousands of kilometres distant from industrial centres) of PAHs and PCBs is testimony to the fact that these compounds are transported over vast distances with air masses and deposited in regions devoid of any human pressure.
Chemical denudation rates and carbon dioxide withdrawal were calculated for the Londonelva basin, an ice-free karst catchment on Svalbard. Runoff was recorded 12 June to 11 October 2000 and water samples were collected daily in August. The chemical denudation rate that month amounted to 2.2 m 3 km À2 . The estimated chemical denudation rate for 2000 was 5.8 m 3 km À2 yr À1 or 303 S meq þ m À2 yr À1 , but this rate may be unusually low because basin runoff was only 158 Â 10 3 m 3 , the lowest since recording began in 1992. For other discharge years estimated chemical denudation rates range from 5.8 to 13.3 m 3 km À2 yr À1 or 300-690 S meq þ m À2 yr À1 . The CO 2 withdrawal in August 2000 amounted to 560 kg C km À2 and for the hydrological year 2000 it was 1560 kg C km À2 yr À1 . In 1993, the highest recorded runoff year, withdrawal of CO 2 may have reached 3800 kg C km À2 yr À1 . Figure 2 Mean daily discharges (Q) in Londonelva in the period of runoff recording (12 June to 11 October 2000) with mean daily air temperature (t a ) and precipitation (P) at Ny-Å lesund in the background.Figure 5 Transient carbon dioxide drawdown (TCD) in relation to crustal solute fluxes (CSF) in glacierized Bayelva basin (filled triangles) and ice-free Londonelva catchment (circles).
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