by Dr. Heidelore Fiedler

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) are unwanted by-products of many chemical industrial and combustion processes. The known toxicity and persistence in the environment of some congeners has resulted in many efforts worldwide a) to identify processes which are suspect to generate PCDD/PCDF, b) to determine levels of PCDD/PCDF in environmental compartments (e.g. in soil, sediments, and air), in products (e.g. in chemicals, paper, other consumer products, and food), in residues and emissions (e.g. municipal waste, fly ash, flue gases of incinerators, sewage sludge, etc.), c) to understand transport and distribution of PCDD/PCDF, and d) to determine human exposure. In addition, technological measures were developed to minimize dioxin emissions and exposure. In this paper, fluxes of PCDD/PCDF for the City of Hamburg were evaluated.

With a population of 1.65 million inhabitants, Hamburg is the second largest city in Germany; in addition, Hamburg is a federal state, too. Its area is 755 km². Hamburg has a highly urban industrial infrastructure with 2,200 inhabitants/km² (for comparison: German average = 228 inhabitants/km²). Hamburg has a long „dioxin" history including a former 2,4,5-T production site, the landfill „Georgswerder" and others are contaminated with PCDD/PCDF; in addition, sediments from the harbour and the river Elbe are contaminated with dioxins. Hamburg has several combustion sources (two municipal waste incinerators, one hazardous waste incinerator, steel works, and non-ferrous metal industry).

Since 1983, more than 800 congener-specific dioxin analyses were performed in Hamburg to determine levels of PCDD/PCDF in water, soil, and air. Emissions and residues from industrial processes (e.g. waste incineration, composting, sewer plants, etc.), landfills, and contaminated sites were analyzed for PCDD/PCDF. Finally, special monitoring programs were established to determine dioxin concentrations in vegetables, foodstuffs, meat, and cow milk. The number and quality of dioxin results is unique for any defined region in Germany. All concentrations of PCDD/PCDF were given in I-TEQ (International Toxicity Equivalents).

Almost complete statistical data were obtained for the year 1992; whenever possible, newer data were incorporated into the dioxin balance for Hamburg. Although many PCDD/PCDF analyses did exist for the Hamburg region, external data had to be used, too: e.g. there was no Hamburg-specific dioxin data available for the concentration of PCDD/PCDF in municipal solid waste, in household effluents, etc. In such cases, an expert meeting was held to determine the appropriate data by checking for plausibility and representativeness.

1. Results
1. PCDD/PCDF Reservoirs

An overview on the reservoirs of PCDD/PCDF in Hamburg is shown in Table 1.

Table 1: PCDD/PCDF reservoirs in Hamburg (reference year = 1992)

Compartment	Reservoir (g I-TEQ)	Percentage of Total
Soil (without landfills and contaminated areas)	4,340	68.7%
Sediments of the river Elbe and the harbor	1,980	31.3%
Water of the river Elbe and the harbor	1.1	<0.01%
Air	0.04	<<0.01%
Vegetation	1	<0.01%
TOTAL	6,322	100%

2. PCDD/PCDF in Water and Sediments

Based on measured data it was calculated that a total of 70 g I-TEQ are transported to the city of Hamburg by the river Elbe. To maintain shipment on the river Elbe and the harbor, about 300,000 t of sediments (dry matter) are excavated each year. With these sediments, approximately 23 g I-TEQ were removed from the waterways and deposited on controlled areas (Spülflächen). Thus, just 47 g I-TEQ leave the city of Hamburg and are transported to the North Sea. The mass balance for water (including suspended solids) is given in Table 2.

Table 2: PCDD/PCDF inventories in surface waters, sediments, and urban effluents

Input Pathway	Flux or Reservoir
Input and Output via the River Elbe
Input from river Elbe	70000 mg I-TEQ/a
Effluents from sewer plants	22 mg I-TEQ/a
Runoff (rain) from uncontained areas	60 mg I-TEQ/a
Direct inputs from (small) point-sources	1-10 mg I-TEQ/a
Effluents from river Elbe	47000 mg I-TEQ/a
Excavation of the river Elbe	23000 mg I-TEQ/a
Atmospheric deposition *	220 mg I-TEQ/a
Concentration in sewage sludge	1438 mg I-TEQ/a
Runoff (rain) from roofs and streets	57 mg I-TEQ/a
Household effluents	419 mg I-TEQ/a
Maximum from other sources *	962 mg I-TEQ/a
Stationary reservoir in river Elbe and harbor	1981100 mg I-TEQ
Sediments	1980000 mg I-TEQ
Water	1100 mg I-TEQ

* Calculated by missing amount

3. PCDD/PCDF in Soil

The PCDD/PCDF concentrations in the soil of Hamburg was found to be similar to those found in other German cities. Levels above average were detected in an industrially impacted area in the south-east of Hamburg, on „Spülflächen" containing sediments from the river Elbe, and other areas naturally flooded by the river Elbe. To calculate the dioxin reservoir present in the soil of Hamburg, the total area was split into use categories as shown in Table 3.

By multiplying the size of a given use pattern with the dioxin-relevant depth for agricultural (30 cm), garden (10 cm), horticultural (20 cm) and other uses of soil (litter in forest = 5 cm; forest soils = = 10 cm; sports fields = 10 cm) with soil densities representative for the use pattern and typical PCDD/PCDF concentrations, a total dioxin reservoir of 4.3 kg I-TEQ was calculated to be present in the soils of Hamburg (Table 3). This inventory contains the „Spülflächen" but not the landfills and contaminated areas.

Table 3: PCDD/PCDF reservoirs in the soil of Hamburg

Unit	Area (km2)	Reservoir (g I-TEQ)
Total area of Hamburg (without surface waters)	695	4340
Agricultural or horticultural use	200	690
Pasture / Grassland (Inside embankment)	50	60
Arable land (Inside embankment)	101	420
Gardens	49	210
Recreational areas, including forests	123	140
Forest	43	60
Lawn, parks, cemeteries	58	65
Sport fields / Surface soils	4	4
Children playgrounds	3	3
Areas under natural protection	15	8
Areas impacted by industrial emissions	69	190
Industrial areas	60	180
Open areas along streets	9	10
Other areas	239	330
Areas flooded in the past	31	2830
Areas on outside of embankments	11	960
Pasture / Grassland (Outside embankment)	9	760
Arable land (Outside embankment)	2	200
Spülfelder/Areas filled with sediments	20	1660
Bille-Siedlung (residential area)	0.3	210
Lower layers of walkways and sport fields	33	160
Sport fields	2	20
Roads	33	140

4. PCDD/PCDF in Landfills and Contaminated Areas

Table 4: Reservoir in landfills and contaminated areas

Location	g I-TEQ
Moorfleeter Brack	1400
Landfill Georgswerder	270000
Landfill Müggenburger Straße	100000
Dump Brümmer	360
Landfill Neuhöfer Straße	no estimate possible on present databasis
Ochsenwerder Landscheideweg	Remediated
Former Production Sites
Boehringer production site	6000

5. PCDD/PCDF Emission from Combustion Sources in Hamburg

For Hamburg, PCDD/PCDF emissions to the air are predominantly from industrial and commercial activities, domestic activities (home heating), waste incineration, and traffic (automobiles). In 1992 a total of 6.5 g I-TEQ were emitted from identified and quantified sources in Hamburg. Table 5 gives an overview on the combustion sources and the annual amount of PCDD/PCDF released from these sources to the atmosphere.

In the year 1992, incineration of municipal solid and hazardous waste was the major sector (industry) to emit PCDD/PCDF into the air; an annual flux of 4.5 g I-TEQ was attributed to this category (see Table 5). Retrofitting of the combustion facilities, shut-down of one old incinerator and installation of a new incinerator resulted in a reduction of more than 95 % for the year 1995 (total emissions from waste incineration: less than 0.2 g I-TEQ/a). Emissions from thermal industrial processes, especially from a copper plant and to a minor extent from iron and steel production, generation of aluminium, and smoke-houses were also of importance. The contribution from generation of energy - fossil fuel power plants and combustion of sewer gas - was low when compared to the total amount of PCDD/PCDF emitted. Relatively large uncertainties exist for the estimate of PCDD/PCDF emissions from home heating. The best estimate for 1992 was between 70 and 340 mg I-TEQ/a.

Reduction of PCDD/PCDF emissions from industrial sources are shown in Table 6 for MSWI (MSWI II was replaced by the new incinerator MSWI B; the hazardous waste incinerator was retrofitted). As can be seen form Table 7, major reductions from this sector occurred through the retrofitting of the copper plant.

Table 5: PCDD/PCDF emissions to the air from combustion sources in Hamburg

Source	Flux (mg I-TEQ/a)
Stationary Sources
Industry:
Copper industry	1,200
Aluminium industry	8
Iron and steel manufacture	166
Petrochemical industry	0.009
Smoke houses (smoked fish and meat)	8
Others:
Crematories	4-21
Generation of Power:
Power plants (fossil fuels)	69
Industrial wood combustion	150
Combustion of sewer gas	14
Waste disposal in Hamburg
Municipal waste incineration	3,913
Hazardous waste incineration	560
Subtotal Stationary Sources	6,092-6,109
Diffuse Sources
Traffic
Automobiles	250
Households:
Home heating	70-340
Accidental fires in homes	8
Subtotal Diffuse Sources	328-598
Sum of All Known Sources	6,420-6,707

Table 6: Emission reductions for MSWI

Year	MSWI II	MSWI B	MSWI II	HWI	Total
1988/90	1.6		4.4	1.0	7
1992	0.95		3.0	0.56	4.5
1995		0.07	0.07	0.05	0.19

Table 7: Reduction of industrial emissions

Emitter	1988/90	1992	1995
Copper	1.44	1.2	0.5
Aluminum industry	0.15	0.088
Steel industry	0.2	0.166
Petrochemical industry		<0.001
Total	1.79	1.374	<0.6

2. Deposition

For the reference year 1992, the annual mean of PCDD/PCDF levels in the air of Hamburg was determined to be 50 fg I-TEQ/m³ and thus, in the range commonly found in German cities. The annual mean takes into consideration that in Hamburg as well as in other regions, PCDD/PCDF levels in air are higher during the winter months and lower during summer. Assuming a mixing layer of 1,000 m above Hamburg (as is common practice in environmental fate models), an amount of 0.04 g I-TEQ is present in the air column at any time. Multiplication of the air volume with the area of Hamburg and the mean wind speed (4.2 m/s) and assuming that the dioxin concentrations are similar inside the city limits and outside, a total amount of 250 g I-TEQ was transported through Hamburg in the year 1992.

For Hamburg, a mean deposition rate of 10 pg I-TEQ/(m²·d) was determined for the year 1992. Thus, a total of 2.8 g I-TEQ was being deposited on the city’s area in 1992. Compared to the amount of 250 g I-TEQ present in the air, roughly 1% of the total PCDD/PCDF was eliminated from the atmosphere by particulate deposition. Recent results showed that in Baden-Württemberg (Germany) the distribution of PCDD/PCDF between the particulate phase and the gaseous phase is about 1:1 when expressed as I-TEQ. Thus, it can be assumed that the combined particulate and gaseous deposition in 1992 was 5.6 g I-TEQ. Astonishingly, this number is in agreement with the total of 6.5 g I-TEQ/a emitted from all known combustion sources in Hamburg. Table 8 summarizes major results on the concentrations of PCDD/PCDF in the air of Hamburg.

Table 8: Summary of PCDD/PCDF in the air of Hamburg for the year 1992

Flux/Reservoir	Load
Stationary mass:	40 mg I-TEQ
Maximum horizontal flux with aerial transport	250,000 mg I-TEQ/a
Emissions from known sources	6,500 mg I-TEQ/a
Deposition:	2,800 mg I-TEQ/a particulate deposition
	2,800 mg I-TEQ/a gaseous deposition
Total:	5,600 mg I-TEQ/a

3. Fluxes with Waste Streams

Wastes result after the life-cycle of a product and from production processes. The waste streams balanced within the Mass Balance for Hamburg included municipal, commercial, and hazardous (industrial) solid and liquid wastes and sewage sludge. A summary of the PCDD/PCDF fluxes associated with waste management and disposal is given in Table 9.

Table 9: PCDD/PCDF fluxes from waste disposal in Hamburg, 1992 (in mg I-TEQ)

Category/Type	Incineration	Landfill	Reuse/ Recycling	Sum
Wastes for disposal or recycling/reuse
Domestic and bulky residues	10990	15450	--	26440
Commerce and business	8320	11650	--	19970
Cleaning of streets, markets, etc.	1150	1620	--	2770
Industrial waste from Hamburg	2500	4140	--	6640
PCB-containing residues	4150	--	--	4150
Fly ash from industry	--	400	460	860
Organic wastes, domestic	--	--	165	165
Organic wastes, industry, commerce	--	--	300	300
Organic wastes, civil services	--	--	244	244
Waste paper, commercial	--	--	307	307
Waste paper, domestic	--	--	61	61
Textiles, domestic	--	--	4	4
Waste and used wood to be traded	--	--	255	255
Sum wastes for disposal, recycling/reuse	27110	33260	1796	62166
Residues from waste disposal processes
Sewage sludge from effluents	--	1393	45	1438
Fly ash from MSWIs	--	16300	--	16300
Slag from MWI	--	--	2300	2300
Fly ash from HWI	--	15300	--	15300
Slag from HWI	--	790	--	790
Sum residues from waste disposal		33783	2345	36128
Total	27110	67043	4141	98294

In Hamburg more than 41% of all domestic and business waste was incinerated in 1992; this percentage is much higher than the German average (approximately 9%). As Hamburg does not have own landfills for disposal of hazardous waste and residues from waste treatment facilities. 76 g I-TEQ contained in wastes were exported for final disposal outside the city limits. Slags from thermal processes, wastepaper, and organic wastes were further processed for new uses; the amount of PCDD/PCDF contained in these valuable goods was low (4.1 g I-TEQ in 1992) compared to the total amount of dioxins present in collected wastes.

The amount of PCDD/PCDF introduced into agricultural and horticultural soils of Hamburg with compost is low. As can be seen from Table 9, the total amount of PCDD/PCDF contained in organic wastes in Hamburg in the year 1992 was less than 1 g I-TEQ.

4. Human Exposure

Due to regional eating preferences, the contribution of the various food categories to the daily PCDD/PCDF intake showed differences when compared to the average German adult. Thus, PCDD/PCDF intake due to preferred foodstuffs may occur in the range of up to 30 % for the various food categories (see Figure 1). Persons from Hamburg consume much more fish and milk products but less meat products than the average German adult. In terms of PCDD/PCDF intake the plus via fish and dairy products is almost compensated by the minus in meat consumption. The daily PCDD/PCDF intake via food consumption was calculated to 115 pg I-TEQ/d for the normal German adult and 119 pg I-TEQ/d for a person living in Hamburg; this difference is not statistically significant. Thus, the fact to be a resident of the city of Hamburg does not have any impact on human dioxin intake.



Figure 1: Difference in the daily dioxin intake of the normal adult population living in Hamburg (119 pg I-TEQ/d) in comparison to the normal adult population in Germany (115 pg I-TEQ/d) for the major food categories

5. References

FHH (1995) Dioxin-Bilanz für Hamburg. O. Hutzinger, H. Fiedler, C. Lau, G. Rippen, U. Blotenberg, H. Wesp, S. Sievers, P. Friesel, B. Gras, T. Reich, U. Schacht, and R. Schwörer. Hamburger Umweltberichte 51/95. Freie und Hansestadt Hamburg, Umweltbehörde (Eds.). Hamburg September 1995

Friesel P., S. Sievers, H. Fiedler, B. Gras, C. Lau, T. Reich, G. Rippen, U. Schacht, and F. Vahrenholt (1996): Dioxin Mass Balance for the City of Hamburg, Germany. Part 4: Trends of PCDD/PCDF Fluxes. Organohalogen Compd. 28, 89-94

Lau C., H. Fiedler, O. Hutzinger, G. Rippen, H.F. Wesp, S. Sievers, P. Friesel, U. Schacht, B. Gras, T. Reich, and F. Vahrenholt (1996): Dioxin Mass Balance for the City of Hamburg, Germany. Part 1: Objective and Emission Inventory. Organohalogen Compd. 28, 83-88

Lau C., H. Fiedler, G. Rippen, H.F. Wesp, S. Sievers, U. Schacht, P. Friesel, and B. Gras (1996): Dioxin Mass Balance for the City of Hamburg. Part 2: Flux of PCDD/PCDF with Liquid and Solid Wastes. Organohalogen Compd. 28, 237-242

Wesp H.F., G. Rippen, H. Fiedler, C. Lau, O. Hutzinger, S. Sievers, P. Friesel, B. Gras, T. Reich, U. Schacht, and F. Vahrenholt (1996): Dioxin Mass Balance for the City of Hamburg. Part 3: Update of Food Consumption Data and Human Exposure via Nutrition. Organohalogen Compd. 30, 37-42