Talk:Salts in building substrate and subsoils

Author:Hans-Jürgen
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 SO_x- 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				Groundwater	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	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

Literature

[Matthess:1990]	Mattheß, Georg (1990): Lehrbuch der Hydrogeologie 2: Die Beschaffenheit des Grundwassers, Bornträger, Berlin, Stuttgart
[Scheytt:??]	The entry doesn't exist yet.