Nitrates and phosphates in cave waters of Kraków-Częstochowa Upland, southern Poland

Abstract

The paper presents the varied presence of nitrates and phosphates in water from caves located in Częstochowa and Kraków, in urban, strongly anthropogenic conditions, representing the vadose zone of the fissure-karstic-porous massif of Upper Jurassic limestones. Hydrochemical research was carried out by the authors in the Cave on the Stone in Częstochowa in 2012-2015, in caves of the Zakrzówek horst from 1996 to 2002, and in the Dragon's Cave by the research team of J. Motyka in 1995Motyka in -1998. A number of NO 3 and PO 4 measurements were performed in waters sampled at these research sites: 20 measurements each of NO 3 and PO 4 at the Cave on the Stone, 228 of NO 3 and 422 of PO 4 at Zakrzówek, and 19 each of NO 3 and PO 4 at the Dragon's Cave. To assess the quality aspect of N and P compounds in waters from the Cave on the Stone, the results of geochemical modelling were processed using PHREEQC software. In cave waters, the oxidised form of nitrogen NO 3 − predominates; in surface wa- , and the insoluble form CaHPO 4 ; in surface waters, these forms are practically absent. Transformations of water chemistry in 'urban' caves, often centuries old, manifest themselves in, inter alia, the occurrence of multi-ionic waters, including seasonal variations and extremely diversified concentrations, with very high concentrations in subpopulations of NO 3 (0.2-485 mg dm −3 ) and P (0.02-6.87 mg dm −3 ). The common presence of NO 3 in waters of the phreatic zone of the Częstochowa Upland, an area developed in an agricultural direction, is documented by, inter alia, the exploitation of intakes supplying the city of Częstochowa (10-57 mg dm −3 , 2011) and crenological studies from 2008 to 2015 (NO 3 , 2-58 mg dm −3 ), at simultaneously low phosphate concentrations (PO 4 , 0.02-0.24 mg dm −3 ).

Environmental Transformation and the Current State of Hydrogeological Condition in the Wojkowice Area—Southern Poland

“…4 4-20 6.5-9. The transformation of the water chemistry of the springs as a result of human pressure exceeding the value of the natural hydrogeochemical background [62] was as follows: EC 200-700 µS cm −1 in the waters of eight springs; total hardness CaCO 3 100-400 mg L −1 in the waters of 5 springs; Mg 0.5-30 mg L −1 in the waters of 6 springs; HCO 3 60-360 mg L −1 in the waters of 4 springs; SO 4 5-60 mg L −1 and NO 3 0-5 mg L −1 in the waters of all springs, Cl 2-60 mg L −1 in the waters of the "Długosz 36" spring. The limit values for drinking water [63] were found to exceed NO 3 concentrations (50 mg L −1 ) ("Długosza 36", "Pod Morwą", "Psary" springs; 51-73 mg L −1 ) and total hardness (60-500 mg CaCO 3 L −1 ) ("Długosza 36", "Brzeziny", "Strzemieszyce", "Majewskiego Street" springs; 523-650 mg L −1 ) (Table 2, Tables S1 and S3).…”

“…data for the years 1984-2001 and 2012-2015;2 -numbers 1-6 as shown in Figure1; 6 -The range of variability of parameter values for the population of springs 4 -Natural hydrogeochemical background according to[62];5 -according to the[63] and quality class-according to the[60]; n.d. not determined.…”