(introduction...)

Paul H. Brunner, Hans Daxbeck, and Peter Baccini

Introduction

One of the most outstanding features of modern man is the capability to exploit, refine, and consume large masses of raw materials. During the development of mankind from neolithic tribes to highly structured urban societies, the total flow of goods used to support human activities increased by two orders of magnitude (fig. 1). Today, in densely populated areas, the fluxes of many anthropogenic materials surpass natural material fluxes. The main reason for this result is the continuous development of the art and technology of prospecting, extracting, upgrading, and designing new and existing materials. In addition, the population growth of the last few centuries has accelerated the flux of anthropogenic materials (fig. 2).

The huge increase in the consumption of goods has several implications: On one hand, it causes a quantitative problem, since the large mass of used goods has to be recycled or disposed of as waste, and thus financial and natural resources (land, water, and air for dissipation) are required for its management. On the other hand, there is a qualitative challenge: the growth in the consumption of materials such as heavy metals or organic compounds leads to large stocks of potentially hazardous materials in the anthroposphere, and to increased fluxes of materials detrimental to the environment. The data contained in figures 1 and 2 show that the consumption of total goods has increased by about two orders of magnitude, and that the consumption of many trace materials such as lead has increased by six and more orders of magnitude. Thus, it may be concluded that the past growth in the material fluxes is mainly of qualitative and secondarily of quantitative importance.

Fig. 1 Total material consumption from neolithic to modern man (t/c/yr)

Fig. 2 Increase in global and per capita production of lead for the last 7,000 years (Source: Brockhaus, 1967: Settle and Patterson, 1980)

The major goal of environmental protection and waste management is to reduce the material flows at the anthroposphere/ environment interface to sustainable levels. Of the many questions which are still unanswered, the following two seem to be fundamental: (1) What are sustainable levels? (2) How can we reach these levels most efficiently?

Despite the lack of answers, decisions have to be made today about the control of material fluxes. In this situation of uncertainty, a cautious approach is appropriate. A conservative concept may be based upon the comparison of anthropogenic and geogenic fluxes: it can be postulated that anthropogenic material fluxes are sustainable for natural systems if they do not change geogenic concentrations, fluxes, and reservoirs. Thus, the goals for the management of material fluxes from the anthroposphere to the environment (in the past often subdivided into "water-pollution control," "air-pollution control," and "waste management") must be to reduce anthropogenic fluxes to levels that allow natural systems to maintain their steady state at geobiogenic levels. This implies that the output of the anthroposphere will become much smaller in the future.

Considering the growth in materials consumption by several orders of magnitude, it will be necessary to reduce the output by more than one order of magnitude for future effective environmental protection. If the input into the anthroposphere is larger than the output, inevitably the stock in the anthroposphere will grow. According to the laws of thermodynamics, it will never be possible to recycle all materials in the anthroposphere. It is essential that the disposal of wastes that leave the man-made system should yield sustainable fluxes only (c.f. waste treatment residues with "final storage quality": Baccini, 1988).

Hence, input, storage, and output of materials in the anthroposphere are interrelated and cannot be controlled separately. Each measure to control the flux of materials has impacts on all three processes. This is true for global, national, and regional economies. In the future, it will be necessary to answer the question of how to control "industrial metabolism" on all levels in view of regionally and globally sustainable fluxes. In this chapter, we will focus on the regional level, which is the level where most control decisions are made: cities and communities plan and regulate their anthroposphere; people decide to move to a region; companies are attracted by regional advantages; the specific resources of regions offer particular opportunities, etc.

In order to assess and control regional industrial metabolism, a threestep procedure is proposed. The first - scientific and technical - step consists of a regional material balance. It includes the assessment of imports, exports, and internal fluxes of goods and materials in the anthroposphere and environment, and emphasizes the growth and/or depletion of natural and anthropogenic reservoirs. In the second technical and economic - step, the most efficient means to control anthropogenic material fluxes are determined. The third political and social - step consists of the implementation of the measures to control industrial metabolism.

The emphasis of this chapter is on step 1, and the objective is to present a methodology for the establishment of regional material balances, using a case-study on a Swiss region. The main question is how to determine the important processes and fluxes in a region consisting of thousands of anthropogenic and natural processes. The work focuses on fluxes of goods and includes two examples of materials such as lead and phosphorus. The results are used to discuss part of step 2, means to control selected materials in a given region. Economic, political and social issues (steps 2-3) are not treated here. Although the region investigated is located in Switzerland, and the concepts discussed here have been developed there, we believe that the approach and methodology chosen can be applied anywhere.

Continue

Methodology

First, a set of definitions is given to describe the material fluxes through a regional anthroposphere. Next, these definitions are used for a systems analysis of a region. Third, field data are collected for the flux of selected materials through the most important processes. Finally, material fluxes through the region are calculated, and two examples of how to use these results for the control of material fluxes in the anthroposphere are given.

Definitions

Table 1 Terms used for the analysis of the anthroposphere

		Conventional
Notion	Definition	discipline	Method
Material	Chemical element or its compounds	Physics, chemistry	Physical and chemical analysis
Good	Material or materiel mixture	Economics	Market analysis, economics
Process	Transport, trans- formation, and storage	Engineering, bio- logy, economics	Materials accounting, material balancing
Activity	Set of processes and fluxes of goods, materials, energy, and information	Cybernetics, anthropology	Systems analysis

Source: Baccini and Brunner, 1991.

In order to investigate the flow of materials through a regional economy systematically, and to use this information for control purposes, we use the following definitions, summarized in table 1 (Baccini and Brunner, 1991):

A material is a chemical element (e.g. lead, carbon) and its compounds (lead chloride, benzene). Material flows are measured in mass per time units, material fluxes in mass per time and area. The "area,' can be an entire region, a household, or a person; hence the flux unit may be in kg/capita and year.

A good consists of one or many materials, such as a pipe made of lead, or gasoline containing benzene. A good has a negative or positive economic value. In the economic sense, goods can also be energy, information, or services. In this work, we apply the term to material goods only, such as cars, water, or municipal solid wastes.

A process is defined as a transport, transformation, or storage of goods, materials, energy, and information. A transport often involves a change in the value of a good. There are processes possible on all levels: a car engine may be looked at as a process, in same way as a private household, a waste incinerator, a branch of a regional economy, or an entire region.

An activity can be defined as a set of processes and fluxes of goods, materials, energy, and information serving a certain purpose, such as to nourish, to clean, or to transport. The concept of "activities" allows one to evaluate different strategies of control. For example, the activity "to nourish," comprising the production, upgrading, storage, distribution, preparation, and consumption of food, involves large fluxes of nitrogen and phosphorus, which may eventually have a negative impact on water, air, and soil. A material flux analysis of the activity "to nourish," from the fertilizer to the edible meal, will thus reveal the most effective measures for the control of these fluxes.

Fig. 3 The anthroposphere as a man-made system (r = resources, w = wastes)

The anthroposphere is the field where human activities take place; it is embedded in the environment (fig. 3). Sometimes called the manmade biosphere, it can be envisaged as a living organism. It has its own metabolism consisting of the uptake, transformation, storage, and discharge of energy, matter, and information. The anthroposphere can be described as a system of processes, and fluxes of goods, materials, energy, and information (see table 1). There are many regional varieties of the anthroposphere, since it is highly influenced by such parameters as the climate, the topography and geology, the native population and its values, the neighbouring regions, and others. The main goal of the metabolism of the anthroposphere is to supply private households with energy, consumer goods, and information; the target process of all anthropogenic activities is the household. All other processes have merely a supporting function.

The method developed to describe the system "region" is based on processes and fluxes of goods and materials (Baccini and Brunner, 1991). Each flux has a "process of origin" and a "process of destination" and thus is precisely defined. Equally, each process is linked with other processes by means of fluxes. A good X, which flows from process A to process B. is called an output good for process A and an input good for process B. An import good is defined as a good which crosses into the region, whereas an export good leaves the region. The same terminology applies to the flux of materials.

As shown in figure 3, a process is graphically presented by a square, a good by an oval, and fluxes of goods or materials by arrows. Although these definitions seem tedious, they become important as soon as one attempts to link the various data about the flux of materials of individual processes. It is very rare for the measurement of the flux of X as an output good to yield the same result as the measurement of X as an input good into the next process. For example, the figure for consumption of drinking water varies by 20-30 per cent depending on whether it is measured at the water supply (output good) or the consumer (input good).

Systems analysis of a region

Description of the region

The region investigated in this work is the Untere Bünztal (Lower Bünz Valley). This broad valley, which is located approximately 400 m above sealevel, covers 66 km², and is limited on both sides by rolling wooded hills. It forms a single watershed, containing two major but small rivers with a water flow of about 0.5-2 m³/sec. Fifty-six per cent of the land area is used for agriculture, 30 per cent is forested, and 13 per cent represents urban areas. The average precipitation amounts to 1,100 mm, and the average temperature is 8-9 °C. The valley may be called representative for regions in Western and Central Europe as well as for the north-eastern United States.

There are 28,000 persons living in the region, in 9,300 private households located in 12 communities. The average per capita purchasing power of US$30,800 (1986) matches that of other regions in Europe. Fifty-nine per cent of the 11,000 employees work in the production sector, 35 per cent in the service and public sector, and 6 per cent in the primary sector (agriculture). Some 55 per cent of the 1,400 enterprises in the region belong to the service sector, and the remaining 45 per cent are equally divided between production and agriculture. Of the 19 branches present in the production sector, the metal industry branch just dominates with 17 per cent of all employees, followed by the plastic and the construction industries with 13 per cent. Other important branches are the electric/electronic industries (11 per cent), textiles (9 per cent), and others (for details see Rist et al., 1989).

The region may be described as a well-mixed economy with an important fraction of its employees working in a few large companies in the production sector, such as a steel mill and a chemical company.

Analysis of the system

Establishing a systematic and comprehensive regional material balance is a comparatively new undertaking. Hardly any methods and data exist for materials accounting on the local level. For the time being, it is beyond the capacity of any research project to investigate the total material flow of a region; the number of goods and materials (elements and compounds, especially of organic carbon), as well as the number of processes, is far too large. Thus, the art of regional materials accounting is to find the few processes and goods which determine the overall flux of a particular material. The following approach was taken in order to simplify the system "region."

As a first step in designing the systems analysis on a general level, the region can be divided into eight major processes. The next step is a more detailed investigation and a subdivision of each of these processes into subprocesses.

A rough assessment of the most abundant fluxes of goods through private households reveals that about 80-100 t/c/yr of goods flow through an average household (see fig. 1; Brunner and Baccini, 1992). Most of these goods originate from the public services (water, natural gas) and the service sector. The production sector supplies the matrix of the regional anthroposphere, such as buildings, roadways, and the nutrients (food) and energy (fuel) to be distributed by the service sector. A few companies with either a large number of employees or a high (financial) turnover are expected to be important for the flux of goods in and through the region. In order to find these important companies, a detailed knowledge of the region is indispensable.

A valuable tool for this work was an existing database about the places of work and the businesses for each sector and branch in the region. When this database was combined with information about the average financial turnover of places of work, a rank order of the importance of the 1,400 businesses in the region became possible. Of course, a rank order according to such economic criteria is not congruent with a ranking based on the fluxes of goods or materials. In the absence of any such information in the production sector, the economic ranking was useful as a first approach - somewhere to start the survey. One advantage of including economic information in this study was that it opens up the possibility of combining material flux data with net product data, and thus serves as a first approach to the problem of linking ecology and economy.

On the basis of this preliminary investigation, the following five most important processes have been defined in the regional anthroposphere.

PRIVATE HOUSEHOLDS. This process stands for the many processes which take place in a private home in relation to the activities "to breathe," "to nourish" (e.g. shopping, preparation, and consumption of food), "to reside" (construction and maintenance of buildings, heating, purchase and maintenance of furniture, carpets, curtains), "to clean" (laundry, dishwasher, toilet, shower, car wash, cleaning), and "to communicate" (transport of persons, goods, energy, and information). Included are processes (and goods) which serve exclusively the private household but which take place outside of it, such as the use of a motor vehicle for shopping, the use of a sewerage system to collect sewage from households, or part of the telecommunication network for TV and phone. The process "private households" comprises all 1,300 households in the region.

SERVICE SECTOR. This sector includes all the businesses engaged in trade and commerce (e.g. shopping centres, retailers, grocery stores), financial and personal services (banks, insurance companies), the catering trade (hotels, restaurants), transportation, and others. Its main purpose is to serve the private individuals in households.

PRODUCTION SECTOR. This process comprises all businesses which produce machinery, metals, chemicals, food, textiles, furniture, shoes, vehicles, etc., and includes the construction business. The goods of the production sector are mainly delivered to the service sector. A detailed list is given in Rist et al. (1989).

PUBLIC SERVICES. In economic classifications, the public sector is usually included in the tertiary (= service) sector. For this work, a separate process, "public services," was chosen for the following reasons: In the region investigated, public services are responsible for the largest fluxes of goods, namely the supply of water, the collection and treatment of sewage, and the collection of solid wastes. Also, public utilities supply electricity, natural gas, and telephone services. For all these subprocesses, there are extensive and reliable databases available. Thus, the flux of goods between the "public services" and the "private households" is important and well documented, justifying a separation from other, less comprehensively investigated processes.

AGRICULTURE. This term stands for the processes which are necessary to plant, grow and harvest plants and to raise animals. In a separate project, subprocesses of the process "agriculture" were linked with the processes "atmosphere" and "soil" in order to determine the contribution of the agricultural practice to the material fluxes in the soil system. These results have been published before and are not included in this work (don Steiger and Baccini, 1990).

In order to fulfil the requirements for processes of "origin" and "destination," three synthetic processes were introduced: man-made import and export processes in the neighbouring regions, and a process "environment." These are composed of many subprocesses. For simplification, they have not been included in figure 4.

The following illustrates some of the subprocesses. Private households use the good "air" for the activities "to breathe," "to reside" (heating), and "to communicate" (transportation). The process of origin for "air" is the Planetary Boundary Layer (PBL), which is a subprocess of the process "environment." The process of destination for the offgases is again the PBL. The source of drinking water is the subprocess "groundwater" in the environment; a subprocess "distribution of drinking water" in the public services supplies private households with drinking water. The collected and treated sewage is finally transferred to the subprocess "River Bünz" in the environment.

The most general list of fluxes of goods consists of the ten good categories represented by bold arrows in figure 4. A category of goods may contain a few single goods (such as the flux from the public services to private households, consisting of drinking water, natural gas, and a few more items) or several hundred to several thousand goods (such as the flux from the production to the service sector, or from the service sector to private households). (A complete list of goods is given in Rist et al, 1989.)

Initially, 12 materials were selected for this study. Two elements were chosen for detailed investigations: lead (Pb), which is still used partially as an additive in gasoline, and which is contained in many consumer products such as cars, batteries, curtains, ties, corks, and construction materials; and phosphorus (P), which is an essential nutrient for the biosphere, a widely used ingredient in cleaners and dishwashing liquids, and an important agent to prevent boiler scale and corrosion.

Fig. 4 Systems analysis of the region Unteres Bünztal (B = Anthroposphere of region, N = Anthropospheres of neighbouring regions)

Assessment of fluxes of goods and materials

In order to determine the flow of goods through the anthroposphere of the region, two kinds of methods were used. The process "private households" was characterized by results from existing market research studies, and the other processes were analysed by individual surveys of the most important companies and public utilities. These techniques yield sufficient information about the flux of goods, but are in general not applicable to the collection of data about the flux of materials, since neither private households nor many businesses know the material composition of the goods they use. Thus, information about materials was collected from other sources, such as general tables (Ciba-Geigy, 1977) or specific articles about the content of, say, phosphorus in goods like detergents and fertilizers.

Private households

There is abundant information from market research on the average consumption of most goods in private households in many regions. These data cover short-lived goods such as food, cleaning agents, and newsprint, as well as goods with longer residence times (e.g. appliances, furniture, textiles). However, there was no market research information about the Bünztal available. Hence, data were used from regions with similar per capita income and similar household size, two properties which are known to be significant for the comparison of the consumption in households. The projection for the entire region was made by multiplying the number of inhabitants with the average per capita consumption. The hypothesis that the use of figures from other regions may be applied to the Bünztal was tested by comparing data on basic foodstuffs from various regions; deviations were between 5 and 15 per cent and are considered acceptable.

The example of phosphorus (P) in table 2 illustrates the procedure for determining the material flux through the household. Data about the flux of 54 goods was supplied by a market research firm (IHA); the concentration of P was taken from Ciba-Geigy (1977), and the P-fluxes were calculated by multiplying the flux of goods with its P-concentration.

Table 2 Assessment of the P-flux through the average private Swiss household

Goods	Flux of goods (kg/capita/ year)	Concentration of P (g P/kg good)	Flux of P (g P/capita/year)
Milk and milk products	109	0.9	98
Dishwashing detergents	2	31.6	63
Bread	24	1.8	43
Vegetables	30	1.2	36
Cheese	8	3.9	31
Meat	16	1.9	31
Fruits	41	0.7	28
Cleaning detergents	9	2.0	18
Cereals	5	2.9	15
Sausages	10	1.4	15
Eggs	6	2.0	12
Pasta	5	2.0	10
Meals consumed out of house	216	0.6	124
Rest (41 goods with P < 10 g/c/y)	439	n.d.	86
Total	920		610

Source: Brunner et al., 1990.

Fig. 5 Flux of phosphorus through the process "private household," in g P/c/yr (A = Process kitchen, B = Process dishwashing and cleaning, MSW = Municipal solid waste, STP = Sewage treatment plant)

The results on P-input obtained by this procedure were successfully cross-checked with available data on P-output from waste and sewage management (fig. 5).4 The P-flux of all the households in the entire region was obtained by multiplying the per capita flux with the 28,000 inhabitants of the region.

Production sector, service sector, and public sector

For each of the three sectors, branches such as "production of food and drinks," "manufacturing of chemicals," and "public water supply" were defined according to BAS (1985). The number and size (given as number of employees) of the businesses in each branch were taken from BAS (1987). The largest companies of each branch were selected and asked for interviews. This allowed us, as a first step, to reduce the 1,377 businesses to 102 enterprises with more than 20 employees, comprising 6,632 workers, or 64 per cent of the total of the three sectors. In a second step, 29 enterprises were excluded from the survey because, on the basis of their field of business, their material flux appeared to be rather small.

With the support of the local chamber of commerce 73 enterprises were individually approached and asked to participate in the project. Of these, 38 companies participated fully, and 11 were eliminated because they had very small fluxes of goods, or could not supply the necessary information in time. Of the remaining 24 businesses, 10 construction companies were included as an entity (see below), and 12 were not surveyed because of the limited manpower available for this research. Only two did not wish to participate in the study. As a rough assessment showed the importance of one of these companies (a carshredder), indirect methods were used to estimate the contribution of the shredder to the regional material flux. (This indirect method is based upon the assessment of the material balance before and after a particular process: information about the manufacturing of cars, a material balance of a similar car-shredder in another region, and information about the amount and composition of the automobile scrap metal treated in a regional smelter permits a rough estimate of the flow of goods and materials through the car-shredder.)

In addition to the survey of individual companies, comprehensive data about all construction businesses in the region were obtained from the regional market leader of the construction branch. Detailed information about water consumption, waste-water treatment, waste management, and energy consumption was supplied by the public utilities of the 12 regional communities; it was fortuitous that the systems boundary coincides with the boundaries of the communities. Thus, it was possible to cross-check the figures on overall water consumption against waste-water production, the data on individual waste production against the global figure on waste collection and treatment, etc. By such cross-checking, gross errors can be detected.

Table 3 summarizes the fraction of businesses, employees, and material turnover covered for each branch in the survey. Despite the fact that only a few percentages of all businesses were investigated, it was possible to include a large percentage of all employees and a very high percentage of the total turnover of goods.

The participating companies were interviewed by an engineer and an economist. In addition to questions regarding the business structure (field of activity, employees, most important processes of origin, and destination for the goods used/produced), the following specific data were collected:

- List and annual flux of input goods, including energy.
- List and annual flux of output goods, including wastes such as municipal solid waste (MSW), production of waste, waste water, and flue gas.

Table 3 Fraction of businesses, employees, and turnover of goods included in the survey (percentage surv.)

	Number of businesses		Number of employees		Goods turnovera
Branch	Total	% surveyed	Total	% surveyed	1,000t/yr	% surveyed
Food/beverage	18	22	442	73	93	73
Textiles/clothing	18	17	598	29	7	16
Leather/shoes	3	33	249	98	0.07	98
Chemicals	5	20	409	95	25	97
Plastics	10	70	849	98	18	96
Sand/gravel/stones	8	13	351	68	127	68
Metal-processing	57	14	1,136	51	180	96
Electro-technics	15	13	682	55	4	68
Watches/jewellery	14	7	65	51	0.1
Construction	31	32	845	89	478	100
Trade/commerce	50	4	348	34	190	90
Storage/transport	5	20	15	40	16	100
Other (farming, etc)	1,070	0	5,010	0	N. d.	N.d.
Total	1,377	3	11,000	52	1,140	90

Source: Own research.

a. In this table, "good" stands for output goods only, and does not include wastes such as municipal solid waste, sewage, or offgas. For most branches turnover was calculated on the assumption that each branch has a specific turnover per employee, but that in some branches (e.g. metal-processing, trade/commerce) the total turnover is heavily influenced by a few companies; cf. Rist et al., 1989).

The information collected varied in its preciseness. In most cases, it was sufficiently detailed to be directly included in the total regional flux of goods. For instance, a chemical company supplied very elaborate data, including hundreds of raw materials and many output goods. Such data have to be aggregated, however, before they can be used. Most companies also provided information about financial turnover, cash flow, and net product.

Calculation method

The information about the fluxes of goods of the "average" private household and of each business was used to calculate a list of the most important processes and of the most important goods in the region (tables 4 and 5). These calculated figures, however, have errors of +/20 per cent: some information is missing (not all processes have been surveyed), the information does not cover the same time period for all businesses, and the data collected are not always accurate because making measurements or calculations is difficult (solid waste) or impossible (flue gas).

The flux diagrams of lead and phosphorus (figs. 6 and 7) were calculated as follows: A material flux balance was established for each process, using measured and estimated flux and concentration data. As not all fluxes through a process were known, some fluxes had to be calculated as difference of inputs and outputs. When all fluxes through a process are measured, it is often not possible to balance inputs and outputs. The balancing period was one year. The change of reservoirs was taken into account for soils and landfills only; annual inputs and outputs of all other processes were considered in equilibrium. The material balance of each single process was then linked to all other processes, yielding an overall regional balance. This procedure required careful validation of the material fluxes through most processes, since the output fluxes of one process and the input fluxes of the following process do not always correspond. In general, most emphasis was put on those large fluxes that are measurable with the least error.

Table 4 Important processes and total flux of goods through the region, including private transportation

	Flux of goods in kt per year and branch
Branch	Total good	Water	Offgas	Solid waste
Private householdsa	2'56	1'84	630	9.2
Production of chemicals	1'91	1'88	75	4.5
Production of food	600	534	19	0.4
Construction	480	N.d.	N.d.	N.d.
Metal-processing (incl. shredder)	430	60	130	40
Rest	690	280	150	N.d.
Total	6'70	4'60	1'000	54

Source: Rist et al., 1989.

a. Including private transportation.

Table 5 Most important fluxes of goods (In t/c/yr) and their fraction flowing through private households of the region

	Flux in t/c/yr
Good	Total	$ through household
Water	164	41
Air	36	60
Construction materials	18	N.d.
Metals/scrap	12	N.d.
Food/drinks	4	21
Fuel	2	55
Rest	2	26
Total	238	38

Source: Brunner et al., 1990.

Continue

Results

Methodology

Systematology

In order to establish a regional material balance, engineers, scientists, and economists have to work together, develop a common language, collect data from most different sources, and combine these data to reveal regional fluxes. Such cooperation would be facilitated if the same systems analysis approach and a common terminology were used. It is an important future task to educate experts from various fields in the techniques of materials accounting.

Fig. 6 Flow of lead through the region Unteres Bünztal, in t/yr

Fig. 7 Flow of phosphorus through the region Unteres Bünztal, in t/yr

The terms developed and the approach taken in this work are based on four steps. The basis - the first step - is a comprehensive systems analysis of the region, defining the region, the boundaries, the processes, and the link between processes by means of fluxes of goods and materials. This is followed by a rough assessment of the importance of the fluxes of goods, carried out with available or easily accessible information. On the basis of this estimation, those fluxes that have to be measured and assessed in more detail are selected. The last step consists in calculating and validating the regional material fluxes.

The Bünztal project has shown that this procedure is feasible if these four steps are taken as an iterative rather than as a consecutive process: the initial systems analysis may have to be expanded or reduced according to the first assessment of the fluxes, or because of the impossibility of balancing a process or process chain. The calculation of the final results may display a large deficit in a process, thus making it necessary to add supplementary measurements to the third step. Even with heavy expenditure, it may not be possible to balance a process (as in the case of lead in the process "river").

The experience in the Bünztal shows that methods have to be developed to take into account the uncertainty of the individual fluxes for regional material balances. These would allow one to quantify the probability that a deficit or a surplus in a regional balance is not an analytical artefact and that additional fluxes have to be looked for.

Materials accounting

The most demanding task in regional materials accounting is to reduce the very many processes and fluxes of goods to a number that is small enough for analysis and still contains the gross of the fluxes of goods and materials. To achieve this, detailed knowledge of the region is necessary. Thus the cooperation of the region itself is important, and should include the public sector as well as private institutions.

The method applied in this study yields abundant information about the flux of goods through the various sectors and branches of a region. The data about these fluxes can easily be verified by comparing the output and input fluxes of consecutive processes, or entire process chains. The method also yields satisfactory results for materials if the concentration of materials in the goods used is known. This is often not the case. The assessment of the fluxes of Pb and P. as displayed in figs. 6 and 7, requires a detailed analysis of many processes (private households, detergent manufacturing, sewage treatment, waste management, car manufacturing, scrap processing, agricultural practice, and others) and involves laborious and costly investigations. But the main obstacle for regional materials accounting is the lack of information about the composition of today's intermediate and consumer goods. While the producer of the primary raw material still knows the composition of his raw iron, zinc, or ethylene, this information is soon lost on the way to the intermediate manufacturer, and particularly when it reaches the final consumer; end-users buy goods and not materials!

For future regional materials accounting, it is indispensable that the information about the material composition of a good should flow parallel to the information about, say, the price or the weight of a good. And this information should be passed from the process of origin to the next process of destination. This appears to be the only way to collect reliable information about the material make-up of today's complex goods, such as refrigerators, motor vehicles, or houses. Technically, with the data-bank management systems now available, it should pose no problem to carry such information from its origin, through the chain of processes, to the end-user.

Regional fluxes of goods and materials

Flux of goods

The overall anthropogenic flux of goods through the Bünztal is given in figure 8. The most important single good is water, which amounts to 69 per cent of the total flux and is mainly used to transport materials and energy in households and industrial processes. Air, utilized in combustion processes such as heating and motor vehicles, comes second with 15 per cent of the total flux. Construction materials account for 8 per cent, scrap iron and junk cars for 5 per cent, and other import goods for 3 per cent.

Of all aggregated processes, private households have the largest turnover, consuming more than one-third of all goods. The branch "production of chemicals" utilizes 29 per cent of the goods, "food and drink" 9 per cent, construction business 7 per cent, metal processing 6 per cent, and the remaining branches 10 per cent.

The fraction of goods which remains in the region is comparatively small and amounts to less than 10 per cent of the import. It consists chiefly of solids to build the matrix of the anthroposphere like construction materials, and goods from processes which are specific to the Bünztal, like solid wastes from the car-shredder and the metal processing plant. Still, this 10 per cent amounts annually to 20 t/c, or 10 kg/m², or 0.6 million tonnes, for the whole region. Thus, if the future fluxes of goods remain unchanged, the accumulation of goods in the next century might surpass the 1 t/m² range.

Fig. 8 Regional flux of goods through the anthroposphere, in t/c/yr (HH = Private households, CH = Production of chemicals, CO = Construction, ME = Metal processing, FD = Processing of food and drink, R = Others)

More than 90 per cent of the goods leaving the Bünztal region (export) are waste waters and offgases. The processes "waste-water treatment" and "offgas treatment" are thus of chief importance for the quality of the environment of the neighbouring regions. The water consumption in the Bünztal amounts to one-fifth of the water input into the region, and one-tenth of the water leaving the region; the dilution potential of the surface waters is low. The ratio of geogenic to anthropogenic fluxes is much higher for the good "air"; it is around 1:500,000, thus permitting a strong dilution of offgases.

The observed flux of goods through the regional anthroposphere supports the notion of the anthroposphere as a biological organism. An important difference from the metabolism of other living things is the large amount of water, which is used to transport the excrete (anthropogenic wastes) out of the region. The activity "to clean" seems to be organized less efficiently in the anthroposphere than in natural systems. In both the biota and the anthroposphere, food, fuel, and air are goods that are important in supporting energy metabolism.

Flux of materials

In this project, the main emphasis was put on the two materials phosphorus and lead. Figs. 5 and 6 and table 2 have shown how such fluxes were determined. In the following paragraphs, it is explained how the regional balance of these materials can be used for resource management and environmental protection.

LEAD. About 340 t/yr of Pb are imported, and about 280 t/yr are exported; the difference of 60 t/yr is stored in the region (see fig. 5). The main lead flux consists of Pb contained in used cars, which are shredded in a large shredder with a capacity of more than 100,000 cars per year. The lead flux through private households is two orders of magnitude smaller; it comprises 1.6 t of Pb in leaded gasoline (which can be easily measured with high accuracy), and 5.6 t Pb in household goods (which have been determined from the Pb concentration in MSW, and thus do not represent the actual consumption of lead in households).

Much of the lead from the car-shredder is processed in a steel mill within the region, which produces iron rods for construction, filter ash from a baghouse, and furnace slag. Owing to the chemical/ physical behaviour of lead, most of the lead (200 t/yr) is concentrated in the filter ash, and some is contained in the mild steel (70 t/yr). These goods are exported and re-used; thus about 80 per cent of the lead imported into the region leaves the region again. The nonmetallic shredder residue contains about 60 tons of lead; at present, this residue is landfilled.

RESOURCE MANAGEMENT. The landfill of the non-metallic shredder residue is the largest sink for lead in the region. It can be assumed that after a decade of landfilling this stock is the most important regional reservoir of lead. Therefore, the careful management of this stock is or will become extremely important. On the one hand, the lead in the landfill poses a threat to the hydrosphere. On the other hand, it may be an important resource for the future.

Following the goals introduced in the Introduction, the shredder residue should be transformed into a good which releases sustainable fluxes only. In addition, the objectives of resource conservation require that the material be in a concentrated and re-usable form. Unfortunately, the good "shredder residue" is far from attaining these two goals, since the lead is highly diluted with organic matter and may be mobilized during landfilling. A possible solution is to treat the shredder residue thermally, thus removing the organic matter and concentrating lead in the fly ash. Further treatment is required to render the fly ash immobile; since solidification with binders like cement dilutes the potential resource of lead and makes it more difficult to re-use, other techniques such as vitrification should be attempted. The final residue should preferably be disposed of in monofills, which contain one type of mixture of concentrated materials only. (Of course, if cars were designed with sustainable development in mind, direct recycling of single car parts might become possible, which would make the shredder in the region obsolete. Direct recycling, however, seems only to be a future option.)

ENVIRONMENTAL PROTECTION. The regional lead balance allows the setting of limits for the leaching of lead from the wastes as well as for emissions from the thermal treatment of wastes and goods. The largest regional sink of lead is the landfill. The good which contains the largest fraction of lead is the residue from the car-shredder. This waste does not yet have "final storage" quality; when it is landfilled, long-term biogeochemical reactions occur, which may mobilize the lead and other materials contained in the landfill. The geogenic flux of lead through the River Bünz is about 30 kg/yr. If the landfill releases about 1 kg/yr of lead, the geogenic flux will be changed less than by its natural variations. This means that, of the total content of about 1,000 tons of Pb in the landfill (corresponding to 10-20 years of landfilling), only about 1 ppm may be mobilized per year. Thus, the future regional goal for the treatment of shredder wastes can be defined as the production of a residue that releases not more than about 10 ppm of the mass of lead when landfilled. (Of course, other materials have to be considered as well).

One technical option for producing a residue with "final storage" quality would be incineration, followed by immobilization of the incineration residues. During thermal treatment, between 40 and 60 per cent of the lead is transferred to the flue gas. Air-pollution-control techniques allow the removal of most, but not all, of the lead from the gas stream. If the lead flux in the filtered flue gas is below 5 kg/yr, the incinerator emissions will not markedly change regional lead concentrations in the soil. A load of 5 kg Pb for 1,000 years in the soil reservoir of ~400 t equals an increase of about 1 per cent, if it is assumed that 80 per cent of the lead is retained in the soil. The flux of 5 kg/yr corresponds to 0.02 mg(Pb)/Nm³. Considering the lead in the raw gas as about 30 t/yr, a removal efficiency of more than 99.98 would be required - a value that can be achieved only if the best available airpollution-control technique is applied. (A similar calculation for lead fluxes from the incineration of municipal solid wastes demonstrates that the allowable emissions are about five times higher (0.1 mg(Pb)/Nm³). The reason for this is the lower overall flux of MSW and lead when compared to the shredder residue).

PHOSPHORUS. The main import goods for P in the Bünztal region are fertilizers and feedstock, the main internal P-fluxes are the agricultural cycle soil-plant-animal-soil, and the main export pathway is the River Bünz (see fig. 7). Most of the P-input into the process industry is from cereals, which are stored temporarily in a large industrial stock. The import flux (229 t/yr) surpasses the export flux (168 t/yr); thus, about 60 tons of P are accumulated annually in the region, and the stock of P in the soil of the region is increasing.

The amount of P in the River Bünz is mainly determined by three processes. The soil, as a result of surface run-off, erosion, and leaching, contributes ~17 t/yr, the sewage-treatment plant (STP) 19 t/yr, and unknown processes such as landfills or illegal effluents 10 t/ yr. In this study, the fluxes from the third category were not investigated. The River Bünz receives ~46 t P/yr, which is about 1.6 times more than the initial load when entering the region. If the elimination of P in the sewage-treatment plant were maximized, about 13 t/yr could easily be eliminated from the river. By contrast, it is not possible to influence the fluxes due to erosion and leaching from the soil in the short term; as long as the reservoir soil is increased, the flux from this process will increase even more. Owing to the high input of P from past and current agricultural practice, the flux of P to the surface waters also will remain high in the future.

The accumulation of P in the soil cannot be detected in the short term by soil analysis (this is true for heavy metals and trace substances in general): because of the heterogeneity of the soil, as well as the limited accuracy of sampling and laboratory analysis, a change in the soil concentration becomes significant only after decades. The material balance approach, however, allows the detection of a potential accumulation before large reservoirs have been developed, and thus can serve as an early-warning system. According to the values given in figure 7, the concentration of P in the soil of the Bünztal increases by about 1 per cent per year and thus will double within roughly 70 years. (In the past, the stock of lead in the soil grew annually by 0.5-1 per cent owing to the use of leaded gasoline.)

Regional materials accounting may be used as a powerful tool for soil protection: the most efficient means of decreasing the P-load of the soil can be assessed using figure 7. The flux of P is mainly due to the two activities "to nourish" and '`to clean." It was recognized several decades ago that P can be the limiting factor for the eutrophication of surface waters. In areas where eutrophication of lakes is a serious problem, the time-span between scientific recognition of its cause and preventative action was about two decades. Most actions concerned the replacement of phosphate-based detergents, that is, processes and goods involved in the activity "to clean." In the region investigated, the turnover of P resulting from the activity "to nourish" is nearly one order of magnitude larger than that from cleaning purposes (see table 2 and fig. 7). In future it will be of great importance to reduce in time the material fluxes for the activity "to nourish" to regionally balanced levels. This suggests that regional materials accounting should be applied as an early-warning tool, and that strategies should be developed which allow a decrease in the time-lag between the recognition of a problem and the implementation of measures to control it (table 6).

Table 6 Results and consequences

Result	Consequences
1. Anthropogenic fluxes > geogenicfluxes	Short-term increase in concentrations in air and waste water, long-term accumulation in soil and sediments
2. Import in region > export from region	Accumulation in the anthroposphere, accumulation in landfills---->future resource potential
3. Private household as chief process of regional meta- bolism	Importance of municipal solid waste (MSW); management for the control of material fluxes at the anthropospheretenvironment interface; final storage concept; products from MSW treatment as new intermediate and long-term resources
4. New strategy of regional material management replaces end-of-pipe environmental protection	Materials accounting on all levels; efficient control of material fluxes; design for multiple and long term re-use

Source: Own design.

Conclusions

1. If the goal of environmental protection is to conserve the quality of water, air, and soil for a long period of time, the contribution of anthropogenic materials must not change geogenic fluxes and reservoirs beyond their natural variations. This means that measures to limit the flux from the anthroposphere to the environment have to be based on regional characteristics: the area of a region, its geology, climate, reservoirs of water, air and soil, population density, the activities of the population, etc., determine which fluxes from the anthroposphere fulfil the above criteria. If the geogenic material flux is relatively small, as in the case of the water flux of the Bünztal, the admissable per capita level of anthropogenic material fluxes is much lower than in a region with abundant geogenic resources. Owing to the large population density and the high per capita turnover of the region investigated, both the sink "soil" and the relatively small conveyer belt "surface water" receive large anthropogenic inputs. The concentrations of metals and phosphorus in the soil are constantly increased; the concentrations and fluxes of many materials in the River Bünz are enlarged on their way through the valley. Regional material balances allow us to identify the most effective measures for the control of material fluxes in a region.

2. In general, the material imports and exports of modern urban regions are not in equilibrium. In the case under consideration, nearly 10 per cent of the total material flux remains in the region and is accumulated, particularly in the anthroposphere (infrastructure) and in the soil (landfills, topsoil). In fact, if imports of solid goods and fuels are considered alone, the accumulation amounts to 50 per cent of the import flux. Hence, the stock of materials is increasing. In future, this stock has the potential for becoming the region's largest waste problem, as well as serving as its major resource. As a new goal of resource management, it is suggested that materials should be kept within the anthroposphere; thus, resources should be conserved by multiple re-use, and the flux of materials to the environment (landfills, soil, and sediments) should be minimized. Engineers and designers should make sure that the material composition of a good is such that the re-use of all materials becomes possible for consecutive life cycles. Mining should be replaced by recycling. If materials are efficiently managed, the re-use of anthropogenic materials requires less energy than primary production from ores (steel, paper, glass, aluminium). However, this strategy will be successfully implemented only if the designing process is supplemented by the new objectives of a long-term sustainable metabolism of the anthroposphere.

3. In urban areas, the key processes for material fluxes are private households. They are characterized by a large turnover and a growing stock of materials. Hence, the management of wastes from households is an important part of regional material management. Recently developed integrated concepts are based on the principle that waste treatment should minimize long-term risks, and that it should produce only three kinds of residuals: (1) goods with final storage quality; (2) goods with adequate properties and markets for recycling; and (3) sustainable emissions (Brunner and Baccini, 1992).

4. A strategy for limiting inputs and outputs at the anthroposphere/environment interface, and for controlling materials within the anthroposphere itself, will replace the present practice of end-of-pipe oriented environmental protection. In order fully to exploit the potential of materials management for efficient resource conservation and environmental protection, it is essential to identify the key processes within a region and to establish their annual material balance. Study of the Untere Bünztal has shown that data on the flux of goods are abundant and readily available; but for most materials, there is not enough information to establish a regional balance. Therefore, traditional financial bookkeeping has to be supplemented by material bookkeeping on all levels, such as those of private and public households, primary production, agriculture, trade and commerce, waste-treatment facilities, etc. Such accounting is not totally new: it is already customary for materials like gold, plutonium, and morphine-based drugs, and is well established in the banking sector, the nuclear industry, and in health care. In the case of private households or small and medium-sized enterprises, it could be delegated to specialized institutions while large enterprises could do it for themselves. If the information about material fluxes from the processing of ores to the manufacturing and distribution of goods can be linked to an overall material flux, regions will have an important tool to maximize the use of their resources and to minimize environmental impacts. In the future, regions which use materials accounting for their planning and management may gain considerable economic advantages (see table 6).

References

Baccini, P., ed. 1988. The Landfill, Reactor and Final Storage. Lecture Notes in Earth Sciences, 20. Berlin, Heidelberg, and New York: Springer Verlag.

Baccini, P., and P. H. Brunner. 1991. Metabolism of the Anthroposphere. Heidelberg and New York: Springer-Verlag.

Brunner, P. H., and P. Baccini. 1992. 'Regional Materials Management and Environmental Protection." Waste Management and Research 10, no. 1.

Brockhaus, F. A. 1967. Brockhaus Enzyklopädie, vol. 2. Wiesbaden: ATF-BLIS, p. 655.

BAS Bundesamt fur Statistik. 1985. Allgemeine Systematik der Wirtschaftszweige 1985 [General Systematology for Economic Sectors 1985]. Bern: Federal Office of Statistics.

- 1987. Die eidgenössische Betriebszählung 1985 [Swiss Federal Census of Places of Work 1985]. Bern: Federal Office of Statistics.

Ciba-Geigy. 1977. Wissenschaftliche Tabellen Geigy [Scientific Tables Geigy]. Basel: CibaGeigy Ltd.

Rist, A., H. Daxbeck, and P. H. Brunner. 1989. Überblick über den Güterumsatz in Industrie und Gewerbe des 2. Sektors im Unteren Bünztal [Survey of the Material Turnover in the Production Sector of the Lower Bünz Valley]. EAWAG Project no. 300712. Dübendorf, Switzerland: EAWAG.

Settle, D. M., and C.C. Patterson. 1980. "Lead in Albacore: A Guide to Lead Pollution in Americans." Science 207: 1167-1176.

Von Steiger, B., and P. Baccini. 1990. Regionale Stoffbilanzierung von landwirtschaftlichen Böden mit messbarem Ein- und Austrag [Material Balances of Agricultural Soils]. Liebefeld-Bern, Switzerland: Nationales Forschungsprogramm "Nutzung des Bodens in der Schweiz."