Screening of platinum group metals; Pt, Rh and Pl · 2016. 1. 14. · 1.3 Platinum group elements 7...

SWECO VIAK Hans Michelsensgatan 2 Box 286, 201 22 Malmö Telefon 040-16 70 00 Telefax 040-15 43 47

SWECO VIAK Screening Report 2007:2

Screening of platinum group metals; Pt, Rh and Pl

Client

Swedish Environmental Protection Agency Malmö 2007-12-14 SWECO VIAK AB Södra Regionen Niklas Törneman Cleas Thuresson Uppdragsnummer: 1270170200

S W E C O V I A K S c r e e n i n g o f W F D p r i o r i t y s u b s t a n c e s i n S w e d e n

SWECO VIAK

2

Contents Contents 2 Sammanfattning 3 Summary 5 1 Introduction 7

1.1 Background 7 1.2 Objectives 7 1.3 Platinum group elements 7

1.3.1 Occurrence and sources 7 1.3.2 Solubility and bioavailability 8 1.3.3 Toxicity 9

2 Methods 11 2.1 Sampling strategy 11 2.2 Sampling methods 12

2.2.1 Soil 12 2.2.2 Sediment 13 2.2.3 Sewage Treatment Plant (STP) sludge and water 13 2.2.4 Fish 13 2.2.5 Water 13 2.2.6 Moose 13 2.2.7 Cow 13 2.2.8 Raptor 13 2.2.9 Plants 14 2.2.10 Air 14

2.3 Analytical methods 15 2.3.1 Extraction and analysis 15

3 Results and discussion 16 3.1 Air 16 3.2 Soil 17 3.3 Sediment and fish 20 3.4 Surface water and groundwater 22 3.5 Sewage treatment plants 24 3.6 Higher animals 25 3.7 Plants 26 3.8 Comparison to earlier results 27

4 Conclusions and recommendations 30 5 References 32 Appendix 1 sampling stations in the Stockholm area Appendix 2 Raw data tables (excel)


SWECO VIAK

3

Sammanfattning Bakgrund och metoder

Inom screeningprogrammet 2006 har SWECO VIAK på uppdrag av Naturvårdsver-ket utfört mätningar för att kartlägga förekomsten av katalysatormetallerna Platinum (Pt), Palladium (Pl) samt Rhodium (Rh) i olika matriser i Stockholmsområdet samt i opåverkade bakgrundsområden i Sverige.

Syftet med screeningstudien var att verifiera resultaten från tidigare studier från andra länder där höga halter av katalysatormetaller påvisats i urbana miljöer, att utöka kunskapen om halter av katalysatormetaller i opåverkade bakgrundsområden och i biologiska matriser, samt att mycket summariskt bedöma om katalysatormetal-ler i Sveriges yttre miljö utgör någon miljö- eller hälsorisk.

I Stockholmsområdet/Mälardalen omfattade provtagningen jord, slam och inkom-mande vatten, sediment från dagvattendammar och från sjöar, grundvatten, ytvatten, dagvatten, luft, växter, fisk, nötkreatur, älg samt havsörn. I opåverkade bakgrunds-områden omfattade provtagningen fisk, sediment, jord och luft. Som en generell indikator på urban påverkan valdes koppar, som därmed analysera-des i alla biologiska och abiotiska prov för att fastställa om det fanns någon samvari-ation mellan koppar och katalysatormetaller. Slutsatser och rekommendationer

De huvudsakliga slutsatserna från denna studie var att:

• Pd påträffades i nästa alla biologiska prov medan Pt och Rh sällan eller aldrig återfanns. Resultat från abiotiska matriser visar även att Pd tycks vara det mest mobila ämnet. Detta bekräftar tidigare studier som har visat att Pd är den mest mobila och biotillgängliga katalysatormetallen.

• Halterna av katalysatormetaller var betydligt högre i luftprover nära vägar i Stockholm jämfört med den regionala bakgrundslokalen Råö på västkus-ten.

• Halterna av katalysatormetaller i jord avklingade kraftigt 15 – 40 m bort från vägkanterna i Stockholmsområdet.

• Kvoten mellan Pt och Rh indikerade att fordonskatalysatorer var den främsta källan till katalysatormetaller även om vissa avvikelser förekom.

• Sediment i dagvattendammar innehöll tydligt förhöjda halter av katalysa-tormetaller medan sedimentkoncentrationerna i en sjö i centrala Stockholm var på samma nivå som i de opåverkade bakgrundssjöarna.

• Pd halterna i grundvatten var tydligt förhöjda, t.o.m. i högre än i dagvatten från starkt trafikerade vägar. Detta visar på den höga mobiliteten av Pd.


SWECO VIAK

4

• Resultaten styrker inte att katalysatormetaller i den yttre miljön utgör nå-gon direkt hälso- eller miljörisk. De förhållandevis få proven i vissa matri-ser (framförallt luft och grundvatten) kombinerat med bristen på utförliga riskbedömningar och på ekotoxikologiska data gör ändå att det inte går att helt utesluta att dessa ämnen kan utgöra risker. Den höga transportbenä-genheten och risken för bioackumulering av Pd komplicerar ytterligare riskbedömningen av katalysatormetaller.

Denna studie visade tydligt att det förekom regional lufttransport av katalysatorme-taller. Därför rekommenderas det att luftmätning av katalysatormetaller även sker i mer avlägsna bakgrundsområden, t.ex. Pallas. I nuläget finns inga data om bakgrundshalter av katalysatormetaller i organismer. Därför är det också svårt att bedöma vad de uppmätta Pd halterna i djur och växter innebär. Således rekommenderas det att katalysatormetaller analyseras i historiska biologiska prov från Naturhistoriska Riksmuseets miljöprovbank. Givet de tydligt förhöjda Pd halterna i grundvatten kan det också vara av intresse att analysera ett större antal antal grundvattenprov från urbana och/eller vägnära områ-den med avseende på katalysatormetaller eller enbart Pd. Detta kan förslagsvis sam-ordnas med existerande miljöövervakning av grundvatten.


SWECO VIAK

5

Summary Background and methods

Within the screening program of 2006 SWECO VIAK has had the assignment from the Swedish Environmental Protection Agency to measure the occurrence of Pt, Pd and Rh (Platinum Group Elements, PGEs) in various matrices in Stockholm and background areas in Sweden.

The objectives of the project were to confirm the results from other studies regard-ing the occurrence of PGEs in abiotic matrices, to enhance the knowledge about PGE levels in biological matrices and to briefly assess whether the levels of PGEs found in the environment constitutes an environmental and/or health problem.

A national sampling strategy was devised in which air, soil, sludge, run-off water, run-off water sediments, surface water, animals and fish were sampled in a region supposedly impacted by PGEs from traffic and industrial activities. Stockholm and its surroundings was chosen as the impacted region. Swedish environmental background levels of PGEs in fish and sediments were de-termined in reference lakes and in soils surrounding these lakes. The influence from human activities on these lakes is generally considered to be minimal.

As an indicator of anthropogenic influence, copper was also measured in the same samples as PGEs. The sampling program is summarized in table 2-1. Conclusions and recommendations

The main conclusions from this investigation were:

• Pt and Rh were almost never detected in the biological samples while Pd was consistently detected above the limit of quantification. Most results indicated that Pd occurs in more mobile/soluble/bioavailable forms com-pared to Pt and Rh

• There were considerable higher PGE levels in air samples collected close to heavily trafficked roads in Stockholm compared to a regional back-ground locality (Råö).

• PGE concentrations leveled off to background levels 15 – 40 m away from heavily trafficked roads in Stockholm.

• The Pt/Rh ratio in soil and sediment samples mainly indicated automobile catalyst sources although some deviations occurred.

• Urban run-off water pond sediments had highly elevated PGE concentra-tions while the concentrations in a lake in central Stockholm was at par with the concentrations at background localities in Sweden.


SWECO VIAK

6

• Pd was also a very dominating PGE in groundwater even far above the Pd concentrations in run-off water (ponds).

• The results do not establish that the occurrence of these substances in the Swedish environment pose any direct risk towards humans and/or aquatic ecosystems. Few sampling points in each matrix, a lack of (eco)toxicological data as well as the bioaccumulative nature of Pd makes this conclusion very tentative.

Regional air transport of PGEs was evident in this study and air sampling of PGEs at more remote location is recommended in order to determine the degree of (trans-) national air transport. There are no data on the background concentrations of Pd in biological samples which prohibits any conclusions based on the levels of Pd in biological samples found in this study. It is therefore recommended that PGEs are analyzed in older biological samples from the Environmental Specimen Bank at the Museum of Natu-ral history. Given the elevated Pd levels in ground water it is also recommended that PGEs are measured in more groundwater samples from urban areas and/or in the vicinity of heavily trafficked roads. This could be coordinated with existing monitoring of groundwater.


SWECO VIAK

7

1 Introduction 1.1 Background At present there is a lack of knowledge regarding the emission, distribution and ex-posure for many of the chemicals emitted to the environment. The aim of the screen-ing program financed by the Swedish Environmental Protection Agency is to allevi-ate this lack of knowledge by estimating the occurrence of different chemicals in the environment in relevant matrices (soil, water etc.).

To maximize the information gained from the screening program measurements are made in many matrices at many sites, but with few samples per site. The Swedish EPA is responsible for the screening at the national level and selects the chemicals that are to be included.

Within the screening program of 2006 SWECO VIAK has had the assignment from the Swedish Environmental Protection Agency to measure the occurrence of plati-num group elements (PGEs) in various matrices in Stockholm and background areas in Sweden.

1.2 Objectives The objectives of the project were to:

• Confirm the results from other studies regarding the occurrence of PGEs in abiotic matrices (soil, air, groundwater, surface water and sediment) in urban areas.

• Investigate the levels of PGEs in biological matrices that have not been well investigated previously.

• To very briefly assess whether the levels of PGEs found in the environment constitutes an environmental and/or health problem

1.3 Platinum group elements 1.3.1 Occurrence and sources This report concerns platinum (Pt), palladium (Pd) and rhodium (Rh) hereafter de-noted as platinum group elements (PGEs). There are more elements included in the platinoid group that are not covered by this report. Platinum is used in automobile catalysts, jewellery, as an anti-tumour drug, in cata-lysts in the chemical industry, in electronics and in dentistry as alloys (Kristine et al. 2004). The main uses of palladium are in electronics, as industrial catalysts, in cir-


SWECO VIAK

8

cuitry, in dental alloys, in jewelry and in automobile catalysts (Kristine m.fl. 2004). Rhodium is mainly used with platinum in automobile catalysts and in catalysts in the chemical industry (Habashi 1997). In general, automobile catalysts are considered to be the dominating source of PGEs to the environment (Kristine et al. 2004). PGEs are the active components in automotive catalysts. Platinum and palladium oxidizes CO2 to CO and hydrocarbons to H2O3, while rhodium reduces NOx. In accordance, there seems to be a clear connection between the increasing use of automobile catalysts and increasing environmental PGE concentrations (Rauch and Hemond 2003). The occurrence of elevated PGE levels in a number of terrestrial and aquatic abiotic compartments such as soil, sediments, road dust, surface water, urban and arctic snow, sludge and air particles is very well established (Goméz et al. 2002, Kristine et al. 2004, Ravindra et al. 2004). These studies have shown that the concentration of PGEs in soils and dusts exposed to high-traffic density far exceeds the natural back-ground levels Increasing levels in biotic compartment has also been established although there are considerable fewer measurements. Most biotic measurements have been made in grass and plants in urban areas and in human urine and blood (Goméz et al. 2002, Kristine et al. 2004, Ravindra et al. 2004). In comparison, investigations of PGE levels in animals are severely lacking. 1.3.2 Solubility and bioavailability The metallic forms of PGEs are practically insoluble in water and it was previously believed that PGEs in the environment were relatively inert. However, it has been shown that these metals undergo environmental transformations into more reactive species which may be more soluble, more mobile and more bioavailable. One impor-tant process in this regard is most likely complexation with natural organic matter (NOM), such as humic acids. Pt, Pd and Rh in the form of complexes of chloride and nitrate have also been shown to be relatively mobile and soluble in rainwater at a pH of 4 – 5 (Menzel et al. 2001) PGEs are bioavailable to plants to a variable extent depending on the type of plant, time of contact with the emission source, and the dispersion of the PGE species. Pd is more bioavailable than Rh and Pt and a major route of uptake is via the roots by binding to sulphur in low molecular weight species In a similar manner, Pd is more bioavailable to animals than Pt and Rh. The bioavailable fraction to rats of Pt originating from automobile catalyst may be in the range of 20–30%. Studies show that PGEs, especially Pd, is taken up in the liver and kidney of rats and eels exposed to PGE in the laboratory. It has also been shown that


SWECO VIAK

9

PGEs bind to metal binding proteins (metallothioneins) in liver and kidney. The in vitro solubility of a model substance of Pt particles was only 0.4% in pure water while solubility was 10% in a 0.9% NaCl solution. This is particularly interesting given that in organisms conditions similar to those in a 0.9% NaCl solution are likely to exist. 1.3.3 Toxicity Most studies have focused on allergy related toxicity in the work place environment. The metallic forms of PGE elements are essentially biologically inert. However, the halogenated PGE compounds have a high allergenic potential and the allergic re-sponse to Pt salts increases with increasing number of chlorine atoms, (Ravindar et al. 2004). Soluble PGE salts are toxic, and chronic industrial exposure to them is responsible for a syndrome characterized by respiratory and cutaneous hypersensitiv-ity (Platinosis) (Ravindra et al. 2004). The prevalence of allergic reactions resulting from Pt salt exposure in refineries and in the catalyst production industry is relatively high (Merget and Rosner 2001). Certain Pt compounds are also known to be cyto-toxic, mutagenic and have carcinogenic effects (Merget and Rosner 2001). There are also several Pt based anticancer drugs (most noticeable cisplatin) that exhibit a num-ber of different biological effects that are outside the scope of this report. The ecological effects and human health problems caused by PGE emissions to the environment is largely unknown. There are no scientific reports on any health effects related to non-occupational exposure to allergenic Pt compounds (Merget and Ros-ner 2001). However, given the low levels found to cause sensitization effects, the levels found in the urban environment may be of concern. The German workplace MAK/TLV value of 2 µg/m3 has been recommended as a ceiling value, which should not be exceeded (DFG 1995) and WHO (1991) has suggested that a no ob-served effect level (NOEL) should be based on the maximum concentrations of soluble Pt measured in low exposure areas in the work environment of production facilities (1.5 ng/m3). Since only 0.1 – 1 % of the total Pt in air constitutes soluble Pt salts, a guidance value of 15 – 150 ng/m3 in ambient air has been derived (Merget and Rosner 2001). There are no reported data on ecotoxicological effects of PGEs on terrestrial organ-isms. The effects of PGEs on aquatic organisms are better researched and aquatic ecotoxicological effects levels are presented in Table 1.1. Singer et al. (2005) dem-onstrated that Pd, Rh and Pt were 3 – 4 times more potent than Cd and Pb in induc-ing biochemical responses at the cellular level in zebra mussel which is a clear sign that the aquatic ecotoxicity of these compounds may be high. Ecotoxicological and toxicological data for the PGE are summarized in Table 1.1.


SWECO VIAK

10

Table 1.1 Toxicological properties of PGE compounds

Substance Properties Toxicological Information Guideline values Ecotoxicological Information

Source

Platinum (Pt) Pt is a group VIII platinoid element of the second Transition series. A range of oxidation states are known although the principal oxidation states are II and IV.

The acute toxicity of Pt salts increases with solubility. Rodent oral LD50 for a range of Pt salts varies between 10 to > 1100 mg/kg. Repeated dose toxicity gives a NOEL for administration of PtCl4 for 13 days of 13 mg Pt/kg/day.

PDE (permitted daily exposure for patients, EMEA 2002) = 2.6 µg/kg/day. TLV = 0.002 µg/m3

NOEL (Pt salts) = 1.5 ng/m3

Guideline value for ambient air 15 – 150 ng/m3 (total Pt content)

LC50 Fish 96h: 2,5 mg/l EC50 Daphnia 48h: 0,082 mg/l EC50 Bacteria: 0.025 mg/l LC50 Scud 196 h: 0.11 mg/l

EMEA 2002 Ravindra et al. 2004 Prevent Data-base Merget and Rosner 2001 ECOTOX database (http://cfpub.epa.gov/ecotox/)

Palladium (Pd)

Pd is a group VIII platinoid element of the second Transition series. Its principal oxidation states are II and IV.

Rat oral LD50=5 – 170 mg/kg. in vitro micronucelus assays did not demonstrate any genotoxicity Several reports of Pd allergy through dental alloy exposure

PDE (permitted daily exposure for patients, EMEA 2002) = 2.6 µg/kg/day (based on Pt due the lack pf Pd data)

LC50 Scud 196 h: > 1 mg/l LC50 Scud 196 h: 0.57 mg/l EC50 Tubifex worm 24 h: 0.24 mg/l EC50 Tubificid worm 48 h: 0.142 mg/l

EMEA 2002 Ravindra et al. 2004 ECOTOX database (http://cfpub.epa.gov/ecotox/)

Rhodium (Rh) Rh is a group VIII platinoid element of the second Transition series. Its principal oxidation states are I, II and III

Rat oral LD50=200 and > 500 mg/kg. Simple Rh compounds (i.e. RhCl3) have been reported as genotoxic

PDE (permitted daily exposure for patients, EMEA 2002) = 2.6 µg/kg/day (based on Pt due the lack pf Pd data)

LC50 Scud 196 h: 0.8 mg/l LC50 Scud 196 h: > 3.2 mg/l

EMEA 2002 Ravindra et al. 2004. ECOTOX database (http://cfpub.epa.gov/ecotox/)


SWECO VIAK

11

Figure 2.1 Background sampling stations.

2 Methods

2.1 Sampling strategy A national sampling strategy was devised based on four objectives:

• Determine the environmental concentrations of PGEs in Sweden. • Verify elevated levels in urban areas by sampling in the Stockholm re-

gion. • Investigate background levels by sampling in background areas from

Northern to Southern Sweden. • Since few PGE measurements have been made in higher animals, deter-

mine the PGE concentrations in fish, cow, moose and raptor.

Air, soil, sludge, urban run-off water, urban run-off water sediments, surface water, animals and fish were sampled in the Stockholm area which was hypothesized to have elevated levels of PGEs due to high traffic intensity. Environmental background levels in fish and sediments were determined in samples from background reference lakes where the influence from human activities are con-sidered to be minimal; Lake Abiksojaure in the northernmost part of Sweden, Ljusacknen in the middle part of Sweden and Krageholmsjön in the southernmost part of Sweden (Figure 2-1). Soil was also sampled from the areas around these lakes. Background air samples were taken at Råö (Figure 2-1) which is an air sampling station used in the national monitoring for air pollutants, the co-operative program for monitoring and evaluation of long range transmission of air pollutants in Europe (EMEP), and in the Arctic Monitoring and Assessment Program (AMAP). As a general indicator of anthropogenic influence, copper was also measured in the same samples as the PGEs. The sampling program is summarized in Table 2.1.


SWECO VIAK

12

Table 2.1 Number of samples from different localities and in different matrices

2.2 Sampling methods Sampling instructions were given to all personnel. These explained sampling proce-dures and handling of samples during transport. One important issue was that all sampling personnel should avoid ring jewelry since the presence of different metals, especially gold and silver, could contaminate the samples.

2.2.1 Soil Soil was sampled from the topmost layer (0-3 cm) after the removal of dead and living plant parts. Also, stones and larger objects were avoided. Soil samples were collected into diffusion tight clean sampling plastic bags and sent to the laboratory within a day of sampling. Samples were stored frozen until analysis.

Air Soil Sediment Fish Ground water Surface water

STP sludge STP water

Flora Animals Total

Abiskojaure 1 1 1 3

Ljusacknen 1 1 1 3

Krageholmssjön 1 1 1 3

Back-ground

Råö 1 1

Hornsgatan 1 1

Essingeleden 1 1

Norrtull 3 1 4

Hanveden 1 1

Västra Haninge 3 3

Sorbusdammen (run-off water pond)

1 1 2

Linneaholm (run-off water pond)

1 1 2

Lake Trekanten 1 3

Bromma STP 2 2 4

Urban

Lake Mälaren (prästfjärden)

1 1

Lake Fysingen 2 2

Mälardalen 4 4

Mälardalen (moose)

3 3

Sea eagle 1

Mälardalen (cattle)

3 3

3 9 6 6 2 2 2 2 4 7 42


SWECO VIAK

13

2.2.2 Sediment Sediment samples from both run-off ponds and lakes were collected by means of a kajak sampler. All sediment samples were transferred to clean plastic jars and sent to laboratory within one or two days of collection. They were stored frozen until analy-sis.

2.2.3 Sewage Treatment Plant (STP) sludge and water The staff at the sewage treatment plants collected the sludge samples from the an-aerobic chambers in clean plastic jars or in acid rinsed pre burned glass bottles. All STP samples were sent to the laboratory within one or two days of collection. They were stored frozen until analysis.

2.2.4 Fish Only perch (perca fluviatilis) was used in this study. Fish from Ljusacknen were collected using fishing net. Samples from all other lakes were supplied from the Environmental Specimen Bank at the Museum of Natural history (A. Bignert and colleagues). When the fish was gutted glass knives were used to avoid metal con-tamination. All fish samples were stored frozen until analysis.

2.2.5 Water Unfiltrated water was collected in clean plastic jars or in acid rinsed pre-burned glass bottles. Water samples were kept frozen until analysis.

2.2.6 Moose Moose samples were taken from three animals; one heifer from a relatively remote area (Dalarna) and a bull and a cow from areas relatively more exposed to traffic (Sörmland). As moose range over large areas, it is difficult to obtain samples that are certain to be from background areas or areas influenced by anthropogenic activities. Moose samples were kindly provided by the Swedish Association for Hunting and Wildlife Management (Niklas Holmqvist).

2.2.7 Cow Liver samples from cows were supplied from one slaughterhouse/breeder where the cow breeding is based on organic/ecological farming principles (in Swedish, KRAV märkt kött). Despite this, the organically bred cows had some of their pastures close to a heavily trafficked road. The other two liver samples originated from convention-ally bred cows.

2.2.8 Raptor Muscle from a white tailed eagle was supplied from the Environmental Specimen Bank at the Museum of Natural history (A. Bignert and colleagues).


SWECO VIAK

14

2.2.9 Plants Birch leaves and blueberries were collected close to a road with medium traffic den-sity and 200 m further away from the road. The samples were collected in clean plastic jars and stored frozen until analysis.

2.2.10 Air Urban air sampling was performed by the company SLB Analys. Samples were col-lected using a low volume air sampler with a PM10 collector using an airflow of 0.96 m3 / h. Samples were collected on a GN-4 Metricel Membrane filter (0.8 µm) intended for air monitoring applications. The filters were automatically changed once every 24-hour period using an automatic exchange mechanism. In total 13 fil-ters was used giving a total sampling volume of 302 m3 and 317 m3 for Hornsgatan and Essingeleden respectively (Figure 2.1). Air sampling at the background station (Råö) was performed by the Swedish Envi-ronmental Research Institute (IVL). Samples were collected using a high volume air sampler with a flow of approximately 14 m3 / h giving a total volume of sampled air of 12 900 m3. After sampling, the filters were wrapped in aluminum foil and sent to the laboratory where they were stored frozen until analysis.

Figure 2.1 Low volume air samplers used for air sampling at two urban sites in Stockholm.

Hornsgatan Essingeleden


SWECO VIAK

15

2.3 Analytical methods 2.3.1 Extraction and analysis AGS Analytica AB was responsible for all analytical work. Determination of Cu and PGE in environmental samples was done by ICP-SFMS (ELEMENT2, ThermoFisher, Bremen, Germany) equipped with high-efficiency introduction system and with methane addition to the plasma (Rodushkin et al. 2005). Measurements were performed by combination of low and high-resolution modes using operation conditions and measurement parameters described in details elsewhere (Rodushkin et al. 2004). Prior to measurement stage, solid samples were digested using MW-assisted procedure (Aqua Regia+HF). For PGE analysis, analyte preconcentration was accomplished using ion exchange chromatography.


SWECO VIAK

16

3 Results and discussion 3.1 Air PGEs occurred in the air samples at both of the urban sites and at the background locality (figure 3.1). As expected the levels were much higher in the urban areas most likely due to direct impact of traffic related emissions at the urban sites (figure 2.1). Copper levels as indications of anthropogenic influence also co-varied with PGE levels (figure 3.2). It should be noted that the PGE levels at the urban and background localities are not directly comparable because PM10 sampling was used at the urban sites while particles of all sizes were sampled at the background locality. The PM10 fraction is believed to be a more bioavailable fraction than the whole particle fraction (Gómez et al. 2002) which makes it appropriate for air sampling of pollutants. The urban PGE concentrations were at the upper range of values found in a number of previous investigations in the urban environment (Table 3.1). Previous PGE analysis of the PM10 fraction of urban air samples in Gothenburg yielded levels of 1 – 19, 0.1 – 10 and 0.3 – 4 pg/m3 of Pt, Pd and Rh respectively (Rausch et al. 2001) which is well below the ranges found in this study. This may be because the sam-plers in this study were placed very close to the traffic (Figure 2.1).

Figure 3.1 PGE concentrations in air samples from an urban area (Stockholm) and a back-ground sampling station (Råö).

Air

6.5

3.1

0.1

0.7

4.30

0.140

1

2

3

4

5

6

Hornsgatan (urban) Essingeleden (urban) RåÖ (background)

PGE

conc

entr

atio

ns (p

g/m

3)

Pd (pg/m3)

Pt (pg/m3)

Rh (pg/m3)


SWECO VIAK

17

Figure 3.2 PGE concentrations in air samples from an urban area (Stockholm) and a back-ground sampling station (Råö). These air levels were well below the suggested guidance value of ambient air (5 – 150 ng/m3) (section 1.3.3) which indicates that the presence of these compounds in urban air does not constitute an acute risk. The guidance values are however based on data from adults in the work environment and not, for example, on juveniles in the urban environment exposed round the clock. Rh and Pd have to our knowledge not been measured in air samples in background environments and the only previous background Pt measurement had a high limit of quantification (2 µg/m3, Ravindar et al. 2004). The results from Råö indicate me-dium range transport of PGEs (Råö is approximately 100 km away from the closest metropolitan area) and there is a need for monitoring of PGEs in air from more re-mote areas, perhaps as part of the ongoing (trans)national monitoring of air pollut-ants at the much more remote site at Pallas in Northern Finland.

3.2 Soil As expected, the highest PGE levels were found close to the roads in the Stockholm area (Norrtull and Västra Haninge) after which they leveled off with similar concen-trations both 15 and 40 m away from the road (Figure 3.3). The same pattern, with PGE concentrations leveling 10 m away from the road while still being higher than background levels, has been found in other studies (Ely et al. 2001) and it is most likely attributed to automobile exhaust particle deposition and local meteorological patterns (Jarvis et al. 2001).

Air

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

Hornsgatan (urban) Essingeleden (urban) RåÖ (background)

Cu

conc

entr

atio

n (µ

g/m

3)

Cu (mg/m3)


SWECO VIAK

18

Ratios between Pt and Rh have been used for tracing the source of PGMs in the environment since automobile catalysts typically have a Pt/Rh ratio of 5-6 (Rauch et al. 2001). The ratio did not vary to a large degree at the Västra Haninge site indicat-ing a common source (automobile catalysts) of PGEs (Figure 3.4). At the Norrtull site the ratio decreased with increasing distance from the road mostly depending on high Pt concentrations in the sample closest to the road. This could either be an artifact due to spatial variability of PGE concentrations (Jarvis et al. 2001). Alternatively, the high Pt/Rh ratio could be explained by PGEs originating from older automobile catalysts since catalyst aging can increase the ratio from 5.5 to 12 (Rauch et al. 2001).

Figure 3.3 PGEs and Cu in soil along transects away from heavily trafficked roads and at background localities from northern to southern Sweden.

16.80

2.601.5

8

2 2.2 1.90.81

2.4

3.90

0.95 0.5

3.5 4.00

1.10.15 0.330.39 0.14 0.1

20.50

0.94 1.200.13 0.09 0.07

0.00

5.00

10.00

15.00

20.00

25.00

Norrtul

l 1 m fro

m road

Norrtul

l 15 m

from roa

d

Norrtul

l 40 m

from roa

d

Västra

Haning

e 1 m

from roa

d

Västra

Haning

e 15 m

from r

oad

Västra

Haning

e 40 m

from r

oad

Abisko

jaure

Ljusac

ksen

Krageh

olm

PGE

conc

entr

atio

ns (µ

g/kg

TS)

Pd (µg/kg TS)

Pt (µg/kg TS)

Rh (µg/kg TS)

83.9

Urban soil

Background soil

35.3

12.910.5

41.1

16.912.5

67.7

6.51 6.93

0

10

20

30

40

50

60

70

80

Norrtul

l 1 m fro

m road

Norrtul

l 15 m

from roa

d

Norrtul

l 40 m

from roa

d

Västra

Haning

e 1 m f

rom roa

d

Västra

Haning

e 15 m

from roa

d

Västra

Haning

e 40 m

from roa

d

Abisko

jaure

Ljusac

ksen

Krageh

olm

Cu

conc

entr

atio

n (m

g/kg

TS)

Cu (mg/kg TS)

background soilurban soil


SWECO VIAK

19

.

Figure 3.4 The ratio between Pt and Rh in soil samples. PGE background concentrations in the earth crust have been determined to 0.4, 0.4 and 0.06 µg/kg for Pd, Pt and Rh respectively (Ek et al. 2004) while garden soil concentrations the year 1982 were 0.27 – 1.37 and 0.64 – 0.99 µg/kg for Pt and Pd respectively (Ravindra et al. 2004). Consequently, the levels seen 15 and 40 m away from the roads and in the background areas are elevated relative to background. More surprisingly was the fact that the PGE concentrations at the background sites were at par with the urban soil concentrations away from the roads, especially at the Norrtull site. This was most noticeable for Pd which correlates with Pd being the most environmentally mobile PGE (section 1.3.2). The Pt/Rh ratios at the back-ground localities were in the same range as those from the urban areas indicating the same sources (figure 3.4). It should be noted that the very remote Abiskojaure site had the highest copper levels and also relatively elevated PGE levels in the soil. This may be due to local geology, especially considering that copper has been mined in the area during the 17th century. Also, there are a number of metallurgical processing plants present in the northern parts of Sweden and Norway. Such industrial activities have been shown to cause large area dispersion of PGEs (Pyrzynska 2000).

0

2

4

6

8

10

12

Norrtull

1 m

from

road

Norrtull

15 m

from

road

Norrtull

40 m

from

road

Västr

a Han

inge 1 m

from

road

Västr

a Han

inge 15

m from

road

Västr

a Han

inge 40

m from

road

Abisk

ojaure

Ljusa

ckse

n

Krag

eholm

Pt:R

h ra

tio in

soi

l sam

ples


SWECO VIAK

20

3.3 Sediment and fish The Pt/Rh ratios indicated automotive catalysts as the most probable source of PGEs for most sediment samples (Figure 3.5). PGE levels were clearly elevated in sediments of the ponds receiving run-off water from the highly trafficked roads (figure 3.6). PGE levels in sediments from lake Trekanten, situated below Essingeleden (one of Swedens most heavily trafficked highways), were on the other hand comparable to levels in sediments from back-ground lakes. The only exception was Pd whose higher mobility may be the cause for elevated concentrations in the lake Trekanten sediments. The elevated levels found in the run-off water ponds were expected and correlates well with high copper levels (figure 3.6) and the levels found in earlier studies of sediments affected by run off water (Table 3.1). Sediments in ponds specifically designed for treating run-off water are usually treated at waste disposal facilities and does consequently not pose a problem in themselves. If these ponds are connected to other surface water systems they will on the other hand constitute important sources of PGEs to aquatic ecosystems.

Figure 3.5 The ratio between Pt and Rh in sediment samples from urban and background areas

Pt:Rh ratios in sediment samples

0

2

4

6

8

10

12

14

Sor

busd

amm

en:

run-

off w

ater

pond

Linn

éaho

lm:

run-

off w

ater

pond

Lake

Tre

kant

en

Abi

skoj

aure

:la

ke

Ljus

acks

en:

lake

Kra

geho

lmss

jön:

lake

Pt:R

h ra

tio


SWECO VIAK

21

Figure 3.6 PGE and Cu concentrations in urban and background sediment samples Pd was found in perch muscle from all lakes while Pt and Rh were below the limit of quantification (LOQ) (figure 3.7). On the other hand, both Pt and Rh were found in the sediment samples from the lakes as well as all other matrices at both urban and background sites. This reconfirms the higher bioavailability of Pd compared to Pt and Rh (see section 1.3.2). Long range transport of PGEs may occur and it is possible that the Pd levels in perch from the “background” lakes do not represent actual background concentrations, especially since these are at par with concentration in fish from lakes in metropolitan areas (figure 3.7). “True” background PGE levels in aquatic biota are unknown since no PGE analyses in aquatic animals before the introduction of automobile catalysts has been done. It would therefore be of interest to perform such analyses on older

1.60.8 0.50.4 0.72 0.38

0.87

8.1

13.3

0.07 0.11 0.070

3

6

9

12

15

Sorbusdammen:run-off water pond

Linnéaholm: run-offwater pond

Lake Trekanten Lake Abiskojaure Lake Ljusacksen LakeKrageholmssjön

Con

cent

ratio

n (µ

g/kg

TS)

Pd (µg/kg TS)

Pt (µg/kg TS)

Rh (µg/kg TS)

23.8 32.0 36.0 48.1

urban

background

206

275

27.8 28.4

0

50

100

150

200

250

300

Sorbusdammen:run-off water pond

Linnéaholm: run-off water pond

Lake Trekanten Lake Abiskojaure Lake Ljusacksen LakeKrageholmssjön

Con

cent

ratio

n (m

g/kg

TS)

Cu (mg/kg TS)

urban background


SWECO VIAK

22

specimen stored at the Environmental Specimen Bank at the Museum of Natural history in Sweden.

Figure 3.7 PGE and Cu levels in Perch from lakes with anthropogenic influence and back-ground lakes.

3.4 Surface water and groundwater The Norrtull groundwater is situated below the intersection between two of Stock-holm’s most heavily trafficked highways (E4 and E20) while the Hanveden ground-water is in the vicinity of a medium trafficked road (Nynäsvägen). Pd occurred in both groundwater samples at levels higher than other PGEs both in surface and run-off water (ponds) (figure 3.8). Pd is the most mobile PGE (section 1.3.2) and it is not unexpected that this is the most prevalent PGE in groundwater.

Perch (muscle)

0

0.1

0.2

0.3

0.4

0.5

0.6

PrästfjärdenMälaren

Fysingen Fysingen (Liver) Abisko Ljusacksen Krageholmssjön

Pd c

once

ntra

tion

(µg/

kg T

S)

Pd (µg/kg TS)

Limit of quantification for Pt and Rh

anthropogenic influencebackground

1.140.879

10.6

1.421.69

0.785

0

2

4

6

8

10

12

PrästfjärdenMälaren

Fysingen Fysingen (Liver) Abisko Ljusacksen Krageholmssjön

Cu

conc

entr

atio

n (m

g/kg

TS)

Cu (mg/kg TS)

background

anthropogenic influence


SWECO VIAK

23

Figure 3.8 PGE and Cu concentrations in groundwater and surface water from run-off water ponds. Note the log scale on the y-axis. The copper concentrations indicate that the run-off water is impacted by traffic re-lated metals. It is therefore unexpected that the Pd and Rh water concentrations was below LOQ in run-off water ponds and that Pt was found at very low concentrations. A possible explanation is that the PGEs are associated with particles (Ravindra et al. 2004) that quickly deposits in the sediment. These results substantiate that Pt is the least mobile PGE and that Pd may be the PGE of most concern because of its mobility. The Hanveden groundwater well is at the edge of a drinking water supply indicating that the PGE and copper levels found there are of some concern. The PGE levels in surface waters are at least 1000 times lower than the lowest acute aquatic toxicity value previously reported from laboratory experiments (table 1.1).

0.1360.103

0.0009 0.001

0.0135

0.0001

0.001

0.01

0.1

1

Norrtull Hanveden Sorbusdammen Linnéaholm

PGE

conc

entr

atio

n (u

g/l)

Pd (ug/l)

Pt (ug/l)

Rh (ug/l)

surface water (from run-off water ponds)

urban groundwater


SWECO VIAK

24

These results together with earlier studies (table 3.1) indicate that PGEs does not constitute major problems for aquatic ecosystems. The relevance of acute short term toxicity tests are however questionable if the aim is to protect aquatic ecosystems and the low number of ecotoxicological studies precludes the determination of safe PGE concentrations in water (i.e. the predicted no effect concentration, PNEC). It is consequently not possible to exclude the possibility that the PGE levels constitute a risk to aquatic ecosystems.

3.5 Sewage treatment plants One set of samples from the sewage treatment plants (STP) was lost. Figure 3.9 displays concentrations in digested sewage sludge and incoming water from a large STP receiving effluent from various industrial activities. Despite this, the PGE con-centrations were at par or lower than PGE concentrations in soils, sediments and water from the Stockholm area. Sludge represents a medium where the pollutant load is integrated over time and these results as well as previous studies (Table 3.1) dem-onstrate that STPs may not be the most important source of PGEs. One noticeable exception is STPs receiving effluents from hospitals where the Pt levels can be high because of the usage of Pt containing drugs (Pyrzynska 2000).

Figure 3.9 PGE concentrations in STP digested sludge and incoming water

1.1

2.5

0.26

0

0.5

1

1.5

2

2.5

3

STP digested sludge

PGE

conc

entr

atio

n (u

g/kg

)

Pd Pt Rh

0.0007

0

0.0002

0.0004

0.0006

0.0008

STP incoming water

PGE

conc

entr

atio

n (u

g/l)


SWECO VIAK

25

3.6 Higher animals Only Pd was detected in cattle, moose and white tail eagle (figure 3.10) which con-firms the higher bioavailability of Pd compared to Pt and Rh. Very few studies of PGEs in higher animals has been done (Table 3.2) and it is difficult to draw any conclusions when there is only a very limited data set to compare with. One interest-ing observation is that the PGEs were below LOQ in muscle from the organically bred cows (whose pasture is in the vicinity of heavily trafficked roads) while the copper levels were high in these animals. An important question is whether the lev-els seen in figure 3.10 represent naturally occurring levels in unexposed animals or elevated levels caused by anthropogenic activities.

Figure 3.10 PGE and Cu concentrations in cattle, moose and white tailed eagle.

0.6

0.5

0.4

0.2

0.3

0.01

0.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

moose liver(bull)

moose liver(cow)

moose liver(heifer)

cattle muscle,normal farm


cattle muscle,organic farm

white tailedeagle, muscle

PGE

conc

entr

atio

n (µ

g/kg

TS)

Pd (ug/kg TS)

Pt (ug/kg TS)

Rh (ug/kg TS)

Limit of detection for Pt and Rh

53

4.4329.2 37.1

411

16.5

91.8

0

50

100

150

200

250

300

350

400

450

moose liver(bull)

moose liver(cow)

moose liver(heifer)



cattle muscle,organic farm

white tailedeagle, muscle

Cu

conc

entr

atio

n (m

g/kg

TS)

Cu (mg/kg TS)


SWECO VIAK

26

One appropriate way to investigate this would be to analyze PGEs in samples from animals caught in remote areas and pre-dating the introduction of automobile catalysts. These could be supplied from the Environmental Specimen Bank at the Museum of Natural history.

3.7 Plants In a similar manner to fish and animal samples, Pd was the most prevalent PGE in Bluberrries and Birch leaves (figure 3.11). In other studies of plants along roads all three PGEs have been detected at levels above the limit of quantification used in this study. The reason for this discrepancy is unkown. As for other biotic samples there are no information regarding the background levels of PGEs in plants, and analyses of older samples from the Environmental Specimen Bank at the Museum of Natural history would clarify this uncertainty.


SWECO VIAK

27

Figure 3.11 PGE and Cu levels in blueberries and birch leaves at increasing distance from a road.

3.8 Comparison to earlier results Table 3.1 and table 3.2 presents a comparison between the concentrations of Pt, Pl and Rh found in the present study and the results from earlier studies. Apart from indicating whether the PGE levels in this study deviate from what is “commonly” found these tables also indicate where important data gaps remain.

1.3

0.7

0.20.15

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Blueberry 5m from theroad

Blueberry 200 m fromthe road

Birch leaves 5 m fromthe road

Birch leaves 200 m fromthe road

PGE

conc

entr

atio

ns (µ

g/kg

TS)

Pd (ug/kg TS)

Pt (ug/kg TS)

Rh (ug/kg TS)

Limit of detection

0.1

7.477.07

12.1

2.4

0

2

4

6

8

10

12

14

Blueberry 5m from the road Blueberry 200 m from theroad

Birch leaves 5 m from theroad

Birch leaves 200 m from theroad

Cu

conc

entr

atio

n (m

g/kg

TS)

Cu (mg/kg TS)


SWECO VIAK

28

Table 3.1 Comparisons between the PGE concentrations in abiotic matrices in this study and earlier studies abiotic matrices Substance This study Other studies

Platinum 0.95 - 84 0.8-87b Rhodium 0.14 – 20.5 2-18b Urban soil, Stockholm (µg/kg) Palladium 2 – 16.8 0.21-7.2b Platinum 0.15 – 1.1 0.03 – 0.26a Rhodium 0.07 – 0.13 Background soil (µg/kg) Palladium 0.81 – 2.4 Platinum 0.4 – 48.1 4.8 – 54b Rhodium 0.07 – 13.3 0.67 – 9.4b Urban sediment, Stockholm (µg/kg) Palladium 1.6 - 36 13.9 – 38b Platinum 0.38 – 0.87 Rhodium


SWECO VIAK

29

Table 3.2 A comparison between the PGE concentrations in biological matrices in this study and earlier studies. Biological matrices Substance This study Other studies

Platinum


SWECO VIAK

30

4 Conclusions and recom-mendations

The main conclusions from this investigation were:

• Most results indicated that Pd occurs in more mobile/soluble/bioavailable forms compared to Pt and Rh.

• In general, copper was a good indicator of PGE levels, especially in the abiotic samples.

• There were considerable higher PGE levels in air samples collected close to heavily trafficked roads in Stockholm compared to a background local-ity (Råö). The levels at Råö still confirm medium range atmospheric trans-port.

• The PGE concentrations in air collected in Stockholm were well below guideline values although the applicability of these guideline values to an urban population is unclear.

• PGE levels in surface waters were > 1000 lower than the lowest ecotoxi-cological effect concentrations which indicate that PGEs does not consti-tute major risks to aquatic ecosystems. A low number of ecotoxicological studies as well as the fact that Pd may be bioaccumulative make this con-clusion uncertain.

• PGE concentrations leveled off 10 m away from heavily trafficked roads in Stockholm. 15 – 40 m away from these roads the concentrations were similar to those found at background localities in Sweden.

• The Pt/Rh ratio in soil and sediment samples mainly indicated automobile catalyst sources although some deviations occurred.

• Sediments from urban run-off water ponds had highly elevated PGE con-centrations while the concentrations in a lake in central Stockholm was at par with the concentrations at background localities in Sweden.

• Pt and Rh were almost never detected in the biological samples while Pd was consistently detected above the limit of quantification in these sam-ples.

• Pd was also the dominating PGE in groundwater even far above the Pd concentrations in run-off water ponds.

• There are still data gaps regarding the “true” background levels in biologi-cal matrices. This needs to be resolved in order to interpret data from on-going monitoring.

Regional air transport of PGEs was evident in this study and air sampling of PGEs at more remote locations is recommended in order to determine the degree of (trans-) national air transport. This could perhaps be done as a part of the ongoing


SWECO VIAK

31

(trans)national monitoring of air pollutants at the remote site at Pallas in Northern Finland. There are no data on the background concentrations of Pd in biological samples which prohibits any conclusions on the levels of Pd in biological samples found in this study. It is therefore recommended that PGEs are analyzed in older biological samples from the Environmental Specimen Bank at the Museum of Natural history. Given the elevated Pd levels in ground water it is also recommended that PGEs are measured in more groundwater samples from urban areas and/or in the vicinity of heavily trafficked roads. This could be coordinated with existing monitoring of groundwater.


SWECO VIAK

32

5 References Ek, K. H. Morrison, G. M. Rauch, S. (2004) Environmental routes for platinum group elements to biological materials – a review. Science of the Total Environment, 334-335. 21 – 38. Ely, J. C. neal, C. R. Kulpa, C. F. Schneegurt, M. A. Seidler, J. A. jain, J. C. (2001) Implications of platinum-group element concentrations along U.S. roads from cata-lytic converter attrition. Environmental Science and Technology, 35. 3816 – 3822. EMEA (2002) Note for guidance on specification limits for residues of metal cata-lysts. European Medical Agency, Committee for proprietary medicinal products (CMP), London. CPMP/SWP/QWP/4446/00. Engström, E. Stenberg, A. Senioukh, S. Edelbro, R. Baxter, D. rodushkin, I. (2004) multi-elemental characterization of soft biological tissues by inductively coupled plasma-sector field mass spectrometry. Analytica Chimica Acta, 521. 123 – 135. Jarvis, K. E. Parry, S. J. Piper, J. M. (2001) Temporal and spatial studies of autocata-lyst-derived platinum, rhodium, and palladium and selected vehicle derived trace elemnst in the environment. Environmental Science and Technology, 35. 1031 – 1036. Jensen, K. H. Rauch, S. Morrison, G. M. Lindberg, P. (2002) Platinum group ele-ments in the feathers of raptors and their prey. Archives of environmental contami-nation and Toxicology, 42. 338 – 347.

Kristine, H. E. Gregory, M. M. Sebastien, R. (2004) Environmental routes for plati-num group elements to biological materials—a review. Science of the Total Envi-ronment, 334– 335. 21–38. Menzel, C.M. Berner, Z. Stüben, D. (2001) Coupling size-exclusion chromatography and ICP-MS to investigate the speciation of platinum group elements in environ-mental samples. Geostandards Newsletter, 25. 239– 51. Merget, R. Rosner, G. (2001) Evaluation of the health risks of platinum group metals emitted from automotive catalytic converters. The Science of The Total environ-ment, 270. 165 – 173. Pyrzynska, K. (2000) Monitoring of platinum in the environment. Journal of envi-ronmental monitoring, 2. 99N – 103N.


SWECO VIAK

33

Rauch, S. Lu, M. Morrison, G. M. (2001) Heterogeneity of platinum Group Metals in Airborne Particles. Environmental Science and. Technolology, 35. 595-599. Rauch, S. Hemond, H.F. (2003) Sediment-based evidence of platinum concentration change in an urban lake near Boston, Massachusetts. Environmental Science and Technology, 37. 3283– 3238. Ravindra, K. Bencs, L. Van Grieken, R. (2004) Platimum group elements in the environment and their health risks. The science of the total environment, 318. 11-43. Rodushkin, I. Nordlund, P. Engström, E. Baxter, D. C. (2005) Improved multiele-mental analyses by inductively coupled plasma-sector field mass spectrometry through methane addition to the plasma. Journal of Analytical Atomic Spectrometry, 2005, 20. 1250. Rodushkin, I. Engstrom, E. Stenberg, A. Baxter, D.C. (2004) Determination of low abundance elements at ultra-trace levels in urine and serum by inductively coupled plasma-sector field mass spectrometry. Analytical and Bioanalytical Chemistry, 380 (2). 247-257.

Date post:	26-Jan-2021
Category:	Documents
Upload:	others
View:	1 times
Download:	0 times

Screening of platinum group metals; Pt, Rh and Pl · 2016. 1. 14. · 1.3 Platinum group elements 7...

Documents