Salts in building substrate and subsoils
Author:Hans-Jürgen
English Translation by Sandra Leithäuser
back to Origin of Salts
Abstract
Saline solutions often originate from the substrate of an object. Depending on the local conditions, ground-, surface and rainwater contain varying amounts of salt forming ions and thus transport salts into objects.
Groundwater, surface water, rainwater
The moisture that is present in all objects mainly originates from groundwater, surface water or rainwater. Groundwater and rainwater are the reservoirs for structures without horizontal damp proof course. These structures may be damaged by rising damp and moisture from the side due to adjacent soil. Table 1 and 2 show that water can carry differing kinds and amounts of potentially damaging salts. For instance, a groundwater source in Eilsum (Germany) contains lower levels of salts than the rainwater of this area, while another groundwater (probably situated close to the surface) contains unusually high level of salts.
Due to a significant drop in SOx- air pollution levels (in the last years in Germany), the rainwater pollution has become relatively low. However, coastal locations still have to take high sodium chloride (NaCl) levels into consideration.
Table 1: Rainwater and groundwater analysis
| [mg/l] | Rainwater[1] | Groundwater[2] | Groundwater | residential sewage water | |||
| Pr.Nr. | Idensen Id286 | Id287 | Id274 | Id33 | Lübeck (Townhall) near-surface groundwater | in loose sediments (according to [Scheytt:??]The entry doesn't exist yet.) | according to [Matthess:1990]Title: Lehrbuch der Hydrogeologie 2: Die Beschaffenheit des Grundwassers Author: Mattheß, Georg 
|
| K+ | 1.2 | 2.4 | 26.9 | 3.4 | 261 | 1 - 5 | 7 - 15 |
| Na+ | 1.2 | 1.4 | 10.1 | 61.7 | 475 | 10 - 50 | 40 - 70 |
| Mg2+ | 0.4 | 0.3 | 3.4 | 10.0 | 46 | 5 - 20 | 3 - 6 |
| Ca2+ | 5.9 | 3.5 | 66 | 179 | 568 | 50 - 200 | 6 - 16 |
| Cl- | 2.35 | 1.8 | 6.1 | 136 | 940 | 15 - 80 | 20 - 50 |
| SO42- | 10.9 | 3.5 | 23.5 | 179 | 310 | 20 - 150 | 15 - 30 |
| HCO3- | 9.0 | 19 | 217 | 284 | |||
| NO3- | <0.1 | <0.1 | 44.4 | <0.3 | 600 | 0 - 150 | 20 - 40 (ΣN) |
| pH | 6.00 | 7.8 | 8.00 | 7.3 | |||
| Conductivity [µS/cm] | 54 | 48 | 480 | 1200 | |||
Groundwater may contain large amounts of ions, e.g. mineral waters, water containing ferrous substances. Particularly anthropogenic pollution is very prominent.
Table 2: Analysis of rainwater and groundwater near Eilsum (Germany)
| Eilsum[3] | Groundwater | Rainwater | ||
| Pr.Nr. | Ei76 | Ei264 | Ei331 | Ei294 |
| K+ | 281.4 | 3.6 | 10.8 | 2.6 |
| Na+ | 50.8 | 7.1 | 20.2 | 36.3 |
| Mg2+ | 18.3 | 1.3 | 6.7 | 4.4 |
| Ca2+ | 66.4 | 12.2 | 73.9 | 5.7 |
| NH4+ | <0.05 | 1.5 | ||
| Cl- | 74.1 | 13,5 | 36.7 | 60.2 |
| SO42- | 122.0 | 7.7 | 33.1 | 26.3 |
| HCO3- | 542.0 | 29.0 | 25.0 | 6.0 |
| NO3- | 25.4 | 6.2 | 3.1 | 3.7 |
| H2PO4- | 31.0 | |||
| pH-Wert | 7.4 | 7.8 | 6.0 | |
Weblinks
Literature
| [Matthess:1990] | Mattheß, Georg (1990): Lehrbuch der Hydrogeologie 2: Die Beschaffenheit des Grundwassers, Bornträger, Berlin, Stuttgart | |
| [Scheytt:??] | The entry doesn't exist yet. |