- Tytuł:
-
Specjacja wybranych składników rozpuszczonych w wodach gruntowych układu katenalnego na Pojezierzu Poznańskim
Chemical speciation of selected dissolved components of groundwater in the catena of the Poznań Lakeland - Autorzy:
-
Kozłowski, M.
Komisarek, J
Wiatrowska, K - Powiązania:
- https://bibliotekanauki.pl/articles/1819329.pdf
- Data publikacji:
- 2012
- Wydawca:
- Politechnika Koszalińska. Wydawnictwo Uczelniane
- Tematy:
-
wody gruntowe
Pojezierze Poznańskie
specjacja - Opis:
- The purpose of this research was to assess speciations of dissolved components of groundwater in a typical for the Poznan Lakeland catena of arable Albeluvisols and Chernozem. The researches were carried out in the cultivated catchment area of the Przybroda Experimental Station located in the north-central part of the Poznan Lakeland (west part of Poland) within the Szamotuly Plain. Every two or four weeks from 04.2005 to 03.2006 the groundwater samples, from six stationary points (wells) were collected. In groundwater samples the concentration of fallowing ions Ca2+, Mg2+, K+, Na+, HCO3-, CO32-, SO2-4, PO43-, and pH, EC were determined. Taking into consideration that dissolved components in groundwater can occur in many chemical forms, the computer programs Visual Mineq was used to assess their speciations. The observed values of groundwater pH were ranged from 6.3 to 8.3, therefore the simulations of speciation at 7.0, and 8.0 pH were done. The results of the researches indicate, that the quantity of dissolved components in groundwater was connected both with soil location in the relief and properties of soil parent materials. The groundwater of soil located higher in a catena were characterized by lower concentrations of the analyzed components, compared with water of lowest elements of the slope. It would seem that the chemistry of groundwater in P4 well should be characterized by concentrations of the analyzed components similar to those observed in P5 and P6 soils. However, studies show that the quantities of these components in groundwater of P4 well were similar to P1-P3. It could be related to water inflow from the higher parts of catena which are neutralized and less aggressive to components contained in the soil. Result obtained from simulation showed that calcium at pH 7.0 occurs mainly as a free ion (Ca2+), whose share ranged from 85% (P5) to 90% (P3). The second form of calcium was a aqua complex CaSO4(aq) (7-13%), and third-CaHCO3- (1-3%). The content of FCa2+, CaSO4(aq) and CaHCO3- significantly decreases when pH increases to the value 8. From geochemical point of view at a thermodynamic equilibrium state there were conditions suitable for precipitation of calcium in the form of calcite and dolomite. In groundwater of the Albeluvisols calcite is precipitated mainly calcite while in Chernozem dolomite. Magnesium also accrued mainly as a free ion Mg2+ (87-92%), aqua complex MgSO4(aq) and MgHCO3- at pH 7. The increase to pH 8caused the precipitation of magnesium in the form of dolomite. In Albeluvisols (P1-P3) groundwater, this form do not exceed 30% of the total amount of magnesium speciation, whereas in the groundwater of Chernozem (P4-P6) the participation of CaMg(CO3)2was much higher. Potassium and sodium, these two metals occurred mainly as a free ion at 7 and 8 pH. At pH 7.0 in the analyzed groundwater from carbonate speciations bicarbonate (HCO3-) occurred most frequently (75%). Aqua complex H2CO3(aq) was a second speciation of carbonates (from 21% to 22%). CaHCO3- and MgHCO3- accounted for about 1% of all carbonate speciations, but in the groundwater of Chernozem the participation of MgHCO3- was greater than CaHCO3-, while in the groundwater of Albeluvisols vice versa. Significant changes in speciations of carbonates occurred when the pH increased to value 8. At this pH, content of HCO3- decreased to about 60% in groundwater of Albeluvisols while in Chernozem to 67%. The share of H2CO3(aq) also decreased to 2%. This decrease of HCO3- and H3CO3 (aq) in the analyzed groundwater was due to the precipitation of calcite and dolomite. In the P1-P4 wells carbonates could be precipitated both in form of calcite and dolomite (predominantly calcite), while in the groundwater of the P5 and P6 wells in the form of dolomite. In the analyzed groundwater a free ion of SO42- was a dominant speciation of sulphates, whose participation increased from 75-80% (pH 7) to 83-91% (pH 8.0) with increasing pH. Other important forms of sulphates MgSO4 (aq) and CaSO4 (aq) but in the P1-P4 were more CaSO4(aq) then CaSO4(aq), while in groundwater of the P5 and P6 vice versa. At 7.0 pH among phosphate spetiations H2PO4- ion dominated (38-43%), followed by HPO42-(from 34% to 36%). Also, a large percentage of MgHPO4 (aq) and CaHPO4(aq) were observed. In groundwater of P1-P4 wells CaHPO4 (aq) dominated over MgHPO4(aq), when in P5 and P6 reverse. The increase of pH to value 8 resulted in the dominance of HPO42- ion. Result from simulation test showed that analysed elements occur mainly as a free ions and aqua-complexes at 7.0 pH. At a higher pH, from thermodynamic point of view, conditions for precipitation of calcium and calcium-magnesium carbonates occurred. Furthermore, quantity of dissolved elements in groundwater and their speciations are connected with soil (well) location in the catena and properties of soil parent material.
- Źródło:
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Rocznik Ochrona Środowiska; 2012, Tom 14; 607-622
1506-218X - Pojawia się w:
- Rocznik Ochrona Środowiska
- Dostawca treści:
- Biblioteka Nauki
Artykuł