Nirel P.

Pasquini F.

I-Revues

NOVATECH 2010 
1 
Differentiation of copper pollution origin: agricultural 
and urban sources 
Différentiation de l'origine des pollutions en cuivre: 
caractérisation des sources agricoles et urbaines 
 
Pascale M. Nirel, François Pasquini 
 
Service de l'écologie de l'eau, Département du territoire, 23 av. de Sainte-
Clotilde, 1205 Genève, Suisse. (pascale.nirel@etat.ge.ch) 
 
RÉSUMÉ 
Le cuivre est un oligo-élément indispensable à la vie mais il peut également être toxique pour l'homme 
à des doses élevées. Son action biocide sur les algues, les mousses et d'autres microorganismes 
s'exerce par contre, à des concentrations très faibles. Le cuivre n'est pas biodégradable, il peut 
s'accumuler et finir par atteindre des niveaux de concentrations dangereux.  
Son origine dans les eaux est très diverse, outre les teneurs naturelles provenant principalement des 
roches et des retombées atmosphériques, son usage par l'homme provoque des rejets dans 
l'environnement. Ces rejets peuvent être ponctuels (usines, déversoirs d'orage, STEPs…) ou diffus, 
suite au lessivage par les pluies des sols, routes et toitures. 
Sur le canton de Genève, 55% des stations étudiées sont polluées en cuivre c'est-à- dire qu'elles ne 
satisfont pas aux exigences définies par la loi (Ordonnance fédérale sur la protection des eaux, 1998). 
Depuis 13 ans les services cantonaux chargés de la surveillance de la qualité des eaux mesurent les 
polluants métalliques dans les rivières du canton. Ce suivi a permis d'obtenir suffisamment de 
données (plus de 3000 analyses) pour non seulement établir un diagnostic mais également identifier 
l'origine des contaminations. Une analyse phénoménologique de type SIG couplée à une approche 
statistique a permis d'identifier, localiser et caractériser les sources de pollution en cuivre des eaux du 
canton de Genève. Deux sources principales ont été différenciées: une source urbaine et une source 
agricole. La pollution en cuivre d'origine urbaine s'accompagne d'une pollution en Zn concomitante 
(toitures, routes….), ce qui n'est pas le cas des pollutions en cuivre d'origine agricole.   
ABSTRACT 
Copper is a trace element essential to life, yet, at high doses it can be toxic to humans.  At very low 
concentrations it is biocidal on algae, mosses and other microorganisms. Copper is not biodegradable, 
it accumulates in the environment and eventually reach hazardous concentrations levels.  
Copper origin in the waters is very diverse. In addition to natural origins, mainly from rock weathering 
and atmospheric deposition, its human use generates releases into the environment.  These releases 
can be punctual (plants, sewer overflows, water treatment plants ...) or diffuse, i.e. the rain washing of 
land, roads and roofs for instance.   
In the Geneva Canton, 55% of the sites studied are polluted by copper, i.e. they do not meet the 
requirements stipulated by law (Ordonnance fédérale sur la protection des eaux, 1998).  For 13 years, 
the cantonal service in charge of water quality monitoring has been measuring metal pollution in the 
rivers of the district. This survey has provided sufficient data (over 3,000 measurements) not only to 
diagnose the contamination but also to identify its source. A phenomenological analysis (GIS-type) 
coupled to a statistical approach has helped identify, locate and, characterize the sources of copper 
pollution in the waters in the Geneva Canton.  Two main sources have been identified: urban and 
agricultural. Copper pollution from urban origin is accompanied by concomitant Zn contamination, but 
not copper pollution from agricultural origin. 
KEYWORDS 
Aquatic environments, Copper, Characterization of pollution, Pollution sources, Water runoff 
SESSION 2.9 
2 
Introduction 
Copper is a widely used metal employed in many fields: transportation, manufacturing, currency, 
transportation of electricity, construction (roofing, decoration ..) and agriculture (fungicide, herbicide).  
Sources of copper in water are extensive, in addition to natural levels originating from rocks 
weathering and atmospheric deposition, its use by humans induces environmental releases.  These 
releases can be punctual (factories effluents, sewages,  ....) or diffuse (runoffs from land, roads and 
roofs (TDC Environmental Report, 2004).  
The identification of pollution is a first step, but it is the identification of sources that will allow 
preventive measures and appropriate management. The issue of urban runoff impact on water 
systems has become salient, a great deal of attention has been given to the characterisation of the 
urban sources of pollution and its dynamics at national or European levels (VSA, 2002 ; Thévenot, 
2006). 
This work aims at developing a practical methodology to discriminate between the potential origins of 
copper pollution, namely agricultural and urban sources, in order to select suited management tools 
(adaptation of agricultural practices, treatment of roads runoffs, ….).   
1 METHODS 
1.1 Sampling and analysis 
In the context of water quality monitoring in the canton of Geneva, instantaneous water samples are 
taken on a monthly basis and analysed for dissolved metals concentrations in the laboratory.  
The sampling sites are distributed along the rivers of the canton of Geneva.  Samples are collected in 
polyethylene bottles previously washed with nitric acid (Suprapur, Merck) 10% v/v and thoroughly 
rinsed with MilloRo MilliQ water (Millipore).  Within hours of collection, samples are filtered (0.45 µm, 
Millex Durapore, Millipore), acidified with nitric acid 2% v/v (Suprapur, Merck) and stored until analysis.  
The analysis are performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) on a VG-
PQ2 instrument in standard configuration with a Meinhard nebuliser in semi-quantitative mode.  
The accuracy of the measures is estimated using a certified standard: SLRS-4 (NRC).  The values of 
copper and zinc measured (n = 73) are 1.83μg / L ± 0.12 for copper and 1.10μg / L ± 0.16 for zinc, the 
certified values are 1.81μg / L ± 0.01 and 0.93μg / L ± 0.10, respectively.  The analytical laboratory is 
accredited (ISO 17025).  
1.2 Data interpretation 
The grid in use for assessing metal pollution is divided into 5 classes according to the graduated 
modular approach recommended by the Confederation of Switzerland (OFEFP, 1998).  On the basis 
of 12 annual samples one determines a quality class according to range of the 80th percentile. 
 
STATE Cu µg/L Zn µg/L 
Very good <1 <2.5 
Good 1-2 2.5 - 5 
Medium 2-3 5- 7.5 
Mediocre 3-4 7.5 - 10 
Bad >4 >10 
 
In order to link the observed data to soil uses, we also conducted a GIS spatial analysis of type 
(geographical information system (ArcGIS). In complement, we performed a hierarchical statistical 
analysis (2-step cluster analysis, SPSS) to estimate the significance of our results. 
 
NOVATECH 2010 
3 
2 RESULTS AND DISCUSSION 
2.1 Diagnosis 
If we consider the results obtained between 1994 and 2007 (105 sites corresponding to 59 streams), 
their distribution between the 5 quality grades is presented Figure 1. 
Very good
Good
Medium
Mediocre
Bad
12%
31%
10%
11%
34%
 
 
Figure 1: Distribution of sampling sites quality according to copper contamination. 
It should be noted that 56% of the stations do not meet the requirement of the Federal regulation for 
the protection of waters.  This is not up to the goal and implies the identification and characterisation of 
sources in order to implement corrective measures. 
Metallic fingerprints have been extensively used to characterise sources contribution to contamination. 
Some approaches rely on normalisation (Masson et al., 2006), other consider individual or metal 
groups as tracers (Gounou et al, 2006).  
In order to differentiate sources of copper pollution one must identify and characterise them (Thevenot 
et al. 2007).  The main suspected sources are the urban area (roofs, fairway metal and urban settings, 
and the agricultural zone (particularly vineyards and orchards).  Concerning the urban source, one can 
assume that copper will be accompanied by other metals.  Several studies (Gromaire-Mertz et al., 
1999; Turer et al. 2001; Herngren et al., 2005; Robert-Sainte et al., 2009) show simultaneous 
contamination by copper and zinc in urban runoff. In agricultural zones, especially vineyards and 
orchards, Cu is extensively used as a fungicide (Célardin et al., 1989; Natali, 1994). We then made the 
hypothesis that the extend of Zn contamination could be used to discriminate between Cu sources.  
Zn contamination in our sampling sites in presented  Figure 2. Zn distribution between quality classes 
is very contrasted compared to Cu with "only" 29% of stations not meeting legal the requirements.  
The dissimilarity between copper and zinc distributions is consequential and shows that zinc 
contamination in the canton is relatively less problematic than copper contamination. Nevertheless, the 
distinction between Cu and Zn distributions is compatible with our hypothesis. 
 
SESSION 2.9 
4 
Very good
Good
Medium
Mediocre
Bad
46%
25%
10%
3%
12%
 
 
Figure 2: Distribution of sampling sites quality according to zinc contamination. 
 
2.2 Spatial analysis 
 
In order to determine whether there are common sources of copper and zinc (which would confirm the 
hypothesis of a "cogeneration" in urban areas) and in order to locate them, we will consider the 
relationship between contamination of copper and zinc in different areas. Our approach consisted in 
representing the spatial distribution of our combined results according to Cu and Zn concentrations 
(80th centile of 12 measurements) in regards of soil use (Figure 3). 
We observed 4 types of situations:  
 both Cu and Zn satisfy the requirements (43 stations out of 101, i.e. 42% of cases, blue dots)  
 neither Cu nor Zn satisfy the requirements (24 stations out of 101, i.e. 24% of cases, red dots)  
 Cu does not meet the requirement but the Zn does (31 stations out of 101, i.e. 31% of cases, 
orange dots)  
 Cu meets the requirement but Zn does not (3 stations out of 101, i.e. 3% of cases, khaki dots)  
The areas meeting the requirements for both Cu and Zn lie on "large" systems, in areas less 
anthropised as the headwater or the left bank of the Rhone at the exit of the canton - an area mostly 
occupied by forests.   
It appears that some rivers are particularly affected by both Cu and Zn contamination. Most of them 
are located in urban areas, downstream STPs,  industrial zones, and/or in the downstream part of the 
watercourse. Only 1 stations deviates from this rule, in these case the contamination results from a 
local contamination (special agricultural activity as identified in Seymaz Report, 2008). 
The stations that do not meet the requirements for Cu but do for Zn are located in agricultural area, 
especially vineyards.  
Three sites do not meet the requirements for Zn but do for Cu. Two of them are located downstream a 
site with cooling towers using a Zn based product, the case of the third site remains unexplained. 
NOVATECH 2010 
5 
This confirms our basic assumption, that in case of urban inputs (roofs, channels, etc.) copper 
pollution is accompanied by a discharge of zinc ; whereas pollution from agricultural source is 
characterized by high concentrations of copper and relatively low concentrations of zinc.  Then, the 
simultaneous consideration of 2 contaminants permits to differentiate their sources. 
 
 
Figure 3: Combined copper and zinc contamination with regard to soil occupation. 
 
SESSION 2.9 
6 
2.3 Statistical analysis 
To validate our approach, we conducted a hierarchical analysis (2-step cluster analysis, SPSS).  This 
analysis is commonly used to identify groups in a set of data.  
To this end, we considered monthly results individually (i.e.  3117 samples), rather than the diagnosis 
of each station (80th percentile of 12 samples a year) presented before. This method is more detailed 
than the previous, each analysis being considered individually.  
 
 
 
 Urban and industrial 
zones 
Agricultural zones Other 
Frequency % Frequency % Frequency % 
High Cu and Zn 977 93.9 0 0 0 0 
Very High Cu and Zn t 64 6.1 6 0.9 4 0.3 
High Cu low Zn 0 0 663 99.1 0 0 
Low Cu and Zn 0 0 0 0 1384 99.7 
Total 1041 100 669 100 1388 100 
Table 1: Frequency hierarchical table. 
The 2-step cluster analysis highlighted 4 groups:  
 a group in which Cu and Zn concentrations are high (averaging 3.78 µg/L ± 3.81 and 6.02 µg/L ± 
5.2 respectively),  
 a group in which Cu and Zn concentrations are very high (averaging 28 µg/L ± 42 and 45 µg/L ± 
41 respectively),  
 a group in which Cu concentrations are high and Zn concentrations are low (averaging 3.6 µg/L ± 
3.3 and 2.5 µg/L ± 2.9 respectively),  
 a group in which concentrations of Cu and Zn are low (averaging 1.3 µg/L ± 1.8 and 2.1 µg/L ± 2.0 
respectively).   
Sites contaminated with zinc not with copper are not highlighted because they are not statistically 
significant as a group in reason of their scarcity (130/3098).   
The analysis also permitted to match groups to land use (Table 3) . Their distributions perfectly fits the 
areas identified by mapping.  The 10 cases in which concentrations of copper and zinc are very high 
outside agricultural areas may correspond to accidental pollution. 
These results substantiate and refine the ones obtained with classification map.  
The stations contaminated by both Cu and Zn are separated in 2 groups, namely high Cu and Zn and 
very high Cu and Zn.  This graduation does not improves the determination of the sources but 
highlights the severity of damage.  
3 CONCLUSIONS 
The  extend of copper pollution in rivers of Geneva District has been evidenced. A phenomenological 
approach combining GIS-analysis and statistical analysis has helped identify, locate and characterize 
sources of copper pollution.   
Two main sources have been recognized : one  urban the other agricultural.  Copper pollution from 
urban origin is accompanied by Zn contamination. This is not the case of copper pollution originating 
from agricultural practices. 
NOVATECH 2010 
7 
This approach can help to determine the origins of chronic pollution in order to implement appropriated  
measures of correction:   
 in urban zones, it is necessary to strictly apply the recommendations for the qualitative treatment 
of runoff waters (VSA, 2002; STORM VSA, 2007), 
 in agricultural areas a reasoned approach for using copper based products has to be developed.  
National plans are underway to find tracks in order to reduce the impact of agricultural practices 
on river water quality. However, memory effect from historical contributions could well delay an 
improvement of water quality (Célardin et al . 1989). 
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Différenciation de l'origine des pollutions en cuivre : caractérisation des sources agricoles et urbaines

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Différenciation de l'origine des pollutions en cuivre : caractérisation des sources agricoles et urbaines

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