THE URBAN PIGEON (COLUMBA
LIVIA,
FORMA
URBANA)
-
A B I O M O N I T O R FOR T H E L E A D B U R D E N OF T H E E N V I R O N M E N T G U S T A V A. D R A S C H
Institut fiir Rechtsmedizin der Ludwig-Maximilians-Universitiit Miinchen, Frauenlobstr. 7a, D-8000 Miinchen 2, F.R.G. * DAGMAR
W A L S E R and J O S E F K O S T E R S
Institut f a r Gefliigelkrankheiten der Ludwig-Maximilians-Universitiit Miinehen, Mittenheimer Str. 54, D-8042 Oberschleiflheim, F.R.G.
(Received April 1986) Abstract. The concentrations of lead in the femura (Pb-F) and the 5-aminolaevulinic-acid-dehydratase
in blood (ALA-D) have been determined in three pigeon populations (50 birds each), caught at urban sites with different traffic densities. The following mean concentrations were found (Pb-F [mg/kg wet w t . ] / A L A - D [U/I]): 10.7/ 18.8 in the low burdened group, 27.9/10.8 in the moderate burdened group, and 49.5/5.6 in the high burdened group. These values were compared with a controlled group of 50 farm pigeons from two remote pigeonries, sited well away from motorways (Pb-F: 1 . 0 / A L A - D : 35.6). The result was a strong positive correlation of the Pb-F and an inverse correlation of the ALA-D to the number of cars per day at the different sites. These local effects contributed much more to the differences of the Pb-F and ALA-D (in comparison with the rural pigeons) than the over-all elevated lead background level in the city. It has been concluded that the pigeon is an almost ideal animal for monitoring a narrow range of environmental lead burden. The main reason for this is that this species is exceptionally stationary; the usual ranges of the feeding, nesting, and sleeping sites of the pigeon are not greater than several hundred meters.
1. Introduction Thedetection, quantitative measurement, and assessment of environmental risks can be performed in two different ways: (I) Chemical and physical measurements of the emissions. (2) Utilization of biological monitoring systems (micro-organisms, plants, animals) for the investigation of the response of living organisms to the burden in the form of adverse effects or accumulation of pollutant(s). The following criteria for the selection of biomonitors, specifically vertebrates, have been established (Luepke 1979; Ellenberg et aL, 1985; Hahn et al., 1985; Wren 1986): The animals must be available in a large number, easily accessible, and widespread for the possibility of international data aquisition. Other conditions are sufficient knowledge of the living range or migration behaviour, the population trend, and the rates of growth and mortality. For the individual, the following criteria must be met: easy identification and differentiation for age and sex, the animals
* Address for reprint requests.
Environmental Monitoring and Assessment 9 (1987) 223-232. 9 1987 by D. Reidel Publishing Company.
224
GUSTAV A. DRASCH
should reach an adequate body weight and age, the feeding behaviour and environment must be known, the kind of exposure to the pollutant of interest must be known, and their sensitivity to the chemical must also be known (whether they metabolize or accumulate it). The selected species should be suitable for investigations both in the lab and in the field. The costs for the aquisition and the keeping of the animals should be appropriate; aquisition, transport, and keeping should be standardizable. Basic data on physiology, reproduction and potential diseases of the animals must exist, and the dose-response-relationship must be known. Data on climate and the environment should be registered. The urban pigeon meets all these preconditions. The widespread distribution of the pigeon in large populations all over the world should be especially stressed and it should be also noted the cities are its natural habitat. For example, the number of pigeons in Munich is estimated at between 10000 and 100000. Further, it is remarkable that this species is exceptionally stationary and the usual ranges of feeding, nesting, and sleeping sites are not greater than several hundred meters. Vogel (1980) assumed the maximal radius of action to be 500-600 m. It can be presumed from previous studies (Ohi 1974, Hutton 1980; Ellenberg et al., 1985; Hahn et al., 1985; Weyers et al., 1985) that birds are sensitive biomonitors for lead, and petrol is the main source of lead in today's environment. At present, the lead content in petrol is limited in West Germany to 0.15 g l-1 and a total reduction to zero will be reached within the next few years.
2. Experimental Design 2.1. SUBJECTS One-hundred-and-fifty urban pigeons (columbia livia, forma urbana) served for this investigation. Three populations (50 birds each) were netted at three urban cites with different traffic densities. In addition, a control group of 50 domestic pigeons (columbia livia, forma domestica) was purchased from rural breeders (see below). 'Urban pigeons' are 'domestic pigeons' which have become wild. Both male and female animals were taken for this study and the mean body weight was determined to be 635 g. 2.2.
NETTING
METHOD
The urban pigeons were netted during routine catching actions periodically performed by the Referat ffir Umweltschutz (department of environment) of Munich. The applied method (a net, falling over a feeding place soon after the feed was scattered) catches only healthy, adult pigeons, because young, weak, or sick animals were initially pushed aside from the feeding (and catching) areas by stronger individuals. After netting, the pigeons were caged for a maximum of one week. There they received feed (Taubenk6rnerfutter, Typ Standard, Fa. Natural, F.R.G., grit (Natural Grit, Fa. Granen, Belgium), and tap-water ad libitum.
T H E PIGEON - A BIOMONITOR FOR LEAD
225
2.3. ANALYTICALMETHODS 2.3.1. Lead Concentration in the Femura (Pb-F) The pigeons were killed, the femur dissected, and the marrow and periostaceum carefully removed. Samples of between 100 to 200 mg were taken from the shaft of the femur, treated with nitric acid, and the lead content determined by ET-AAS (instrumentation: Perkin-Elmer 3030 with D2-compensation, Bodenseewerk PerkinElmer, 0berlingen, F.R.G.) (Drasch, 1982). As certified control samples with a similar matrix were not available, the results were calculated from a calibration curve prepared with lead standards in nitric acid solution. The accuracy of the external calibration method, without matrix matching, was confirmed by simultaneous analyses of 20 digestions using both this method and the standard addition method (coefficient of correlation 0.98). The precision was _+2.5% (double determination). All lead concentrations were calculated in mg Pb/kg wet wt.
2.3.2. 5-Amino-Laevulinic-Acid Dehydratase (ALA-D) in the Blood and its Enhanced Activity after Reactivation with Glutathione (GSH) The active ALA-D (U/I) and the additional proportion, which can be remobilized by GSH, were determined by a modified method (Moder 1983) proposed by Berlin and Schaller (1974). The principle of this method is that at the hem-biosynthesis ALA-D catalyzes the condensation of two molecules 5-amino-laevulinic-acid to porphobilinogene. This reaction product together with Ehrlich's reagent forms a colour complex which can be measured by photometry.
2.4.
CHARACTERIZATION
OF THE
SELECTED
LOCATIONS
The methods for this study were developed and tested in pilot studies on groups of eight pigeons each from several different locations. The main problem was to choose suitable netting places.
Location 1 (control group) Fifty pigeons from two rural pigeonries in Upper Bavaria, remote from any motor way, served as a control population. Location 2 (low-burdened urban park) This location (the 'Hirschau') is a large public park within the city. A low traffic frequency of approximately 500 cars per day results from an adjoining tennis court and a beer garden. The park area is bounded on two sides by urban highways at distances of approximately 1000 and 2000 m from the netting place. Location 3 (moderate-burdened residential area) An open place ('Schyrenplatz') surrounded by blocks of flats represent this location.
226
GUSTAV A. DRASCH
The traffic frequency is estimated at 41000 car units per day. The distance to location 4 (see below) is only 1000 m .
Location 4 (high-burdened traffic area) Location 4 ('Candidplatz') is part of a multi-laned urban highway with a traffic frequency of approximately 107 000 car units per day. A large intersection and a gradient increase the burden further. Additionally, this site is walled on two sides by high blocks of flats.
Calculation of Lead Emissions from the Number o f Cars per Day The lead emissions (g Pb d a y - l) at the different locations were calculated from the traffic density (number of cars per day) and the mean lead emission of one car on the basis of 0.15 g Pb 1- 1 petrol, a mean speed of 20 km h r - l, and a mean duration time of 1 min. at the location area (Umweltbundesamt, 1980).
3. Results 3.1. LEAD CONCENTRATION IN THE FEMUR (Pb-F)
3.1.1. Dependence on Sex In all the populations from the different locations, the Pb-F of the females was higher than that of the males. The significance levels of this sex-dependence increase with the lead burden from 'not significant' (control group) to 'highly significant' (group 4) (see Table I). TABLE I Arithmetic mean values of the detected parameters for a lead burden Population
Sex
n
ALA-D U 1- j
ALA-D+GSH U 1- I
Pb-F m g k g - ~ wet wt.
1 unburdened
male female all
26 24 50
3 6 . 0 8 _+ 3.84 3 5 . 0 4 + 3.03 35.58 _+ 3.48
3 7 . 0 4 + 3.51 35.88 + 2 . 8 2 3 6 . 4 9 + 3.22
0.91 - 0 . 7 9 1 . 2 0 + 1.10 1.04 + 0.95
2 low burdened
male female all
27 23 50
18.72 _.+3.46 18.95 -+ 3.76 18.83 _+ 3.57
29.11 + 2.50 2 8 . 0 5 -+ 3.52 2 8 . 6 2 + 3.03
9.75+3.58 11.78+3.37 10.69-+ 3.59
3
male
28
11.24 _.+2 . 0 9
18.57 + 4 . 6 6
moderate burdened
female all
22 50
10.19 + 1.81 10.78 + 2 . 0 2
16.40_+3.61 17.61 +_4.33
25.65+5.01 30.72 + 4.26 2 7 . 8 8 - 5.30
4 high burdened
male female all
28 22 50
5 . 6 0 + 1.90 5.57 + 2 . 2 2 5.58 -+ 2.03
10.75 __.3 . 5 0 10.06 + 3 . 7 9 10.44 ___3.61
4 5 . 5 7 -+ 4 . 4 0 54.42 + 6.42 4 9 . 4 7 + 6.93
THE PIGEON -- A BIOMONITORFOR LEAD
227
3.1.2. Dependence on the Location
The mean lead concentrations in the femura of the pigeon populations from the four different locations differ significantly from each other (p
LIVIA,
FORMA
URBANA)
-
A B I O M O N I T O R FOR T H E L E A D B U R D E N OF T H E E N V I R O N M E N T G U S T A V A. D R A S C H
Institut fiir Rechtsmedizin der Ludwig-Maximilians-Universitiit Miinchen, Frauenlobstr. 7a, D-8000 Miinchen 2, F.R.G. * DAGMAR
W A L S E R and J O S E F K O S T E R S
Institut f a r Gefliigelkrankheiten der Ludwig-Maximilians-Universitiit Miinehen, Mittenheimer Str. 54, D-8042 Oberschleiflheim, F.R.G.
(Received April 1986) Abstract. The concentrations of lead in the femura (Pb-F) and the 5-aminolaevulinic-acid-dehydratase
in blood (ALA-D) have been determined in three pigeon populations (50 birds each), caught at urban sites with different traffic densities. The following mean concentrations were found (Pb-F [mg/kg wet w t . ] / A L A - D [U/I]): 10.7/ 18.8 in the low burdened group, 27.9/10.8 in the moderate burdened group, and 49.5/5.6 in the high burdened group. These values were compared with a controlled group of 50 farm pigeons from two remote pigeonries, sited well away from motorways (Pb-F: 1 . 0 / A L A - D : 35.6). The result was a strong positive correlation of the Pb-F and an inverse correlation of the ALA-D to the number of cars per day at the different sites. These local effects contributed much more to the differences of the Pb-F and ALA-D (in comparison with the rural pigeons) than the over-all elevated lead background level in the city. It has been concluded that the pigeon is an almost ideal animal for monitoring a narrow range of environmental lead burden. The main reason for this is that this species is exceptionally stationary; the usual ranges of the feeding, nesting, and sleeping sites of the pigeon are not greater than several hundred meters.
1. Introduction Thedetection, quantitative measurement, and assessment of environmental risks can be performed in two different ways: (I) Chemical and physical measurements of the emissions. (2) Utilization of biological monitoring systems (micro-organisms, plants, animals) for the investigation of the response of living organisms to the burden in the form of adverse effects or accumulation of pollutant(s). The following criteria for the selection of biomonitors, specifically vertebrates, have been established (Luepke 1979; Ellenberg et aL, 1985; Hahn et al., 1985; Wren 1986): The animals must be available in a large number, easily accessible, and widespread for the possibility of international data aquisition. Other conditions are sufficient knowledge of the living range or migration behaviour, the population trend, and the rates of growth and mortality. For the individual, the following criteria must be met: easy identification and differentiation for age and sex, the animals
* Address for reprint requests.
Environmental Monitoring and Assessment 9 (1987) 223-232. 9 1987 by D. Reidel Publishing Company.
224
GUSTAV A. DRASCH
should reach an adequate body weight and age, the feeding behaviour and environment must be known, the kind of exposure to the pollutant of interest must be known, and their sensitivity to the chemical must also be known (whether they metabolize or accumulate it). The selected species should be suitable for investigations both in the lab and in the field. The costs for the aquisition and the keeping of the animals should be appropriate; aquisition, transport, and keeping should be standardizable. Basic data on physiology, reproduction and potential diseases of the animals must exist, and the dose-response-relationship must be known. Data on climate and the environment should be registered. The urban pigeon meets all these preconditions. The widespread distribution of the pigeon in large populations all over the world should be especially stressed and it should be also noted the cities are its natural habitat. For example, the number of pigeons in Munich is estimated at between 10000 and 100000. Further, it is remarkable that this species is exceptionally stationary and the usual ranges of feeding, nesting, and sleeping sites are not greater than several hundred meters. Vogel (1980) assumed the maximal radius of action to be 500-600 m. It can be presumed from previous studies (Ohi 1974, Hutton 1980; Ellenberg et al., 1985; Hahn et al., 1985; Weyers et al., 1985) that birds are sensitive biomonitors for lead, and petrol is the main source of lead in today's environment. At present, the lead content in petrol is limited in West Germany to 0.15 g l-1 and a total reduction to zero will be reached within the next few years.
2. Experimental Design 2.1. SUBJECTS One-hundred-and-fifty urban pigeons (columbia livia, forma urbana) served for this investigation. Three populations (50 birds each) were netted at three urban cites with different traffic densities. In addition, a control group of 50 domestic pigeons (columbia livia, forma domestica) was purchased from rural breeders (see below). 'Urban pigeons' are 'domestic pigeons' which have become wild. Both male and female animals were taken for this study and the mean body weight was determined to be 635 g. 2.2.
NETTING
METHOD
The urban pigeons were netted during routine catching actions periodically performed by the Referat ffir Umweltschutz (department of environment) of Munich. The applied method (a net, falling over a feeding place soon after the feed was scattered) catches only healthy, adult pigeons, because young, weak, or sick animals were initially pushed aside from the feeding (and catching) areas by stronger individuals. After netting, the pigeons were caged for a maximum of one week. There they received feed (Taubenk6rnerfutter, Typ Standard, Fa. Natural, F.R.G., grit (Natural Grit, Fa. Granen, Belgium), and tap-water ad libitum.
T H E PIGEON - A BIOMONITOR FOR LEAD
225
2.3. ANALYTICALMETHODS 2.3.1. Lead Concentration in the Femura (Pb-F) The pigeons were killed, the femur dissected, and the marrow and periostaceum carefully removed. Samples of between 100 to 200 mg were taken from the shaft of the femur, treated with nitric acid, and the lead content determined by ET-AAS (instrumentation: Perkin-Elmer 3030 with D2-compensation, Bodenseewerk PerkinElmer, 0berlingen, F.R.G.) (Drasch, 1982). As certified control samples with a similar matrix were not available, the results were calculated from a calibration curve prepared with lead standards in nitric acid solution. The accuracy of the external calibration method, without matrix matching, was confirmed by simultaneous analyses of 20 digestions using both this method and the standard addition method (coefficient of correlation 0.98). The precision was _+2.5% (double determination). All lead concentrations were calculated in mg Pb/kg wet wt.
2.3.2. 5-Amino-Laevulinic-Acid Dehydratase (ALA-D) in the Blood and its Enhanced Activity after Reactivation with Glutathione (GSH) The active ALA-D (U/I) and the additional proportion, which can be remobilized by GSH, were determined by a modified method (Moder 1983) proposed by Berlin and Schaller (1974). The principle of this method is that at the hem-biosynthesis ALA-D catalyzes the condensation of two molecules 5-amino-laevulinic-acid to porphobilinogene. This reaction product together with Ehrlich's reagent forms a colour complex which can be measured by photometry.
2.4.
CHARACTERIZATION
OF THE
SELECTED
LOCATIONS
The methods for this study were developed and tested in pilot studies on groups of eight pigeons each from several different locations. The main problem was to choose suitable netting places.
Location 1 (control group) Fifty pigeons from two rural pigeonries in Upper Bavaria, remote from any motor way, served as a control population. Location 2 (low-burdened urban park) This location (the 'Hirschau') is a large public park within the city. A low traffic frequency of approximately 500 cars per day results from an adjoining tennis court and a beer garden. The park area is bounded on two sides by urban highways at distances of approximately 1000 and 2000 m from the netting place. Location 3 (moderate-burdened residential area) An open place ('Schyrenplatz') surrounded by blocks of flats represent this location.
226
GUSTAV A. DRASCH
The traffic frequency is estimated at 41000 car units per day. The distance to location 4 (see below) is only 1000 m .
Location 4 (high-burdened traffic area) Location 4 ('Candidplatz') is part of a multi-laned urban highway with a traffic frequency of approximately 107 000 car units per day. A large intersection and a gradient increase the burden further. Additionally, this site is walled on two sides by high blocks of flats.
Calculation of Lead Emissions from the Number o f Cars per Day The lead emissions (g Pb d a y - l) at the different locations were calculated from the traffic density (number of cars per day) and the mean lead emission of one car on the basis of 0.15 g Pb 1- 1 petrol, a mean speed of 20 km h r - l, and a mean duration time of 1 min. at the location area (Umweltbundesamt, 1980).
3. Results 3.1. LEAD CONCENTRATION IN THE FEMUR (Pb-F)
3.1.1. Dependence on Sex In all the populations from the different locations, the Pb-F of the females was higher than that of the males. The significance levels of this sex-dependence increase with the lead burden from 'not significant' (control group) to 'highly significant' (group 4) (see Table I). TABLE I Arithmetic mean values of the detected parameters for a lead burden Population
Sex
n
ALA-D U 1- j
ALA-D+GSH U 1- I
Pb-F m g k g - ~ wet wt.
1 unburdened
male female all
26 24 50
3 6 . 0 8 _+ 3.84 3 5 . 0 4 + 3.03 35.58 _+ 3.48
3 7 . 0 4 + 3.51 35.88 + 2 . 8 2 3 6 . 4 9 + 3.22
0.91 - 0 . 7 9 1 . 2 0 + 1.10 1.04 + 0.95
2 low burdened
male female all
27 23 50
18.72 _.+3.46 18.95 -+ 3.76 18.83 _+ 3.57
29.11 + 2.50 2 8 . 0 5 -+ 3.52 2 8 . 6 2 + 3.03
9.75+3.58 11.78+3.37 10.69-+ 3.59
3
male
28
11.24 _.+2 . 0 9
18.57 + 4 . 6 6
moderate burdened
female all
22 50
10.19 + 1.81 10.78 + 2 . 0 2
16.40_+3.61 17.61 +_4.33
25.65+5.01 30.72 + 4.26 2 7 . 8 8 - 5.30
4 high burdened
male female all
28 22 50
5 . 6 0 + 1.90 5.57 + 2 . 2 2 5.58 -+ 2.03
10.75 __.3 . 5 0 10.06 + 3 . 7 9 10.44 ___3.61
4 5 . 5 7 -+ 4 . 4 0 54.42 + 6.42 4 9 . 4 7 + 6.93
THE PIGEON -- A BIOMONITORFOR LEAD
227
3.1.2. Dependence on the Location
The mean lead concentrations in the femura of the pigeon populations from the four different locations differ significantly from each other (p
