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4. Standards for environmental quality
4.1 Air quality
4.2 Climatic situation
4.3 Noise situation
4.4 Available water supply
4.5 Water quality
4.6 Soil quality
4.7 Agricultural and forestry land
4.8 Biotope conditions (special biotope functions)
4.9 Food quality
Depending on the emission conditions and meteorological factors, emission of pollutants into the air leads to atmospheric pollutant concentrations in excess of the natural basic level. The capacity of the atmosphere with regard to the distribution, breakdown and deposition of pollutants can be influenced by man only over small areas and even then only within relatively narrow limits (e.g. topoclimatic factors).
Immissions can be defined in terms of substance mass referenced to the volume of the contaminated air (e.g. mg/m3). Standards in the form of volumetric concentrations are specified for gases in particular (e.g. cm3/m3). Standards for dust emissions are given in the form of particle concentrations (l/cm3) or, in the case of deposition, mass per unit of area and time (g/m2 x d).
The Register of Substances (Section 5) contains immission-related information.
Climatic changes may have a variety of anthropogenic causes, such as:
- changes in surface cover
- irrigation and drainage measures
- action influencing the surface configuration
- creation of lakes
Depending on the extent of such measures and local conditions, the resultant impacts may be either restricted to the specific area concerned (topoclimate) or of a global nature.
The key climate parameters comprise the following:
- temperature and temperature profile
- humidity
- amount of precipitation
- frequency of fog
- strength and direction of wind
- intensity of radiation
Such changes occur above all with regard to the topoclimate, with impacts on
- agricultural production conditions (cold-air "lakes", balancing-out of temperature extremes by expanses of water etc.)
- soil erosion by wind (function of windbreaks)
- living conditions for fauna and flora, particularly for microorganisms and thus also for pathogens
- air quality (distribution of pollutants)
- the population's health and well-being.
Whether a climatic change is rated as positive or negative depends totally on the situation in the case concerned and on the assessment criterion applied (which must be derived from the demands to be fulfilled by the individual environmental elements). Such an assessment will always be receptor-specific.
Although there are no relevant standards in the narrower sense, standards could be developed, at least in the form of desirable requirements to be fulfilled by climatic conditions, on the basis of the conditions leading to the impacts described above.
The noise situation is essentially described in the form of sound immission, which is taken as meaning the effect of sound on an area or on a point within an area.
The following factors are used to describe the noise situation:
- the magnitude of the continuous sound level (measured or calculated as an average level over a specific period, e.g. for the daytime or night)
- the magnitude and number of peak levels
- the frequency of the noises
- the intervals elapsing between the occurrence of noises
- the nature and number of sound sources
Sound immission is generally measured in the form of the A-weighted sound pressure level, expressed in decibels (dB). The A-weighting is based on the sensitivity of the human ear.
To take account of the varying ratings attached to different noise sources, as well as for technical and legal reasons, area-specific ambient quality standards (immission standards) generally distinguish between individual installations or types of equipment and between the following categories of noise sources:
- industry
- traffic: road traffic, rail traffic, shipping, aircraft
- other facilities (e.g. leisure facilities, sports facilities, military installations etc.)
The effect of noise on human beings depends on the latter's physical condition and state of mind as well as the activity being performed (need for mental concentration, acoustic information and regeneration periods). It manifests itself in the form of demonstrable mental and physical reactions.
The extent to which particular sounds are regarded as constituting a noise nuisance is also determined by the social and cultural acceptance of specific sounds; to a certain degree, this acceptance is unrelated to the magnitude of the sound level.
In order to assess an existing noise situation or one which may result from a planning or construction measure, it is essential to determine the sound immission.
To this end, measuring and calculation procedures have been developed (e.g. in the Federal Republic of Germany: RLS 90, DIN 18005, Schall 03, 04) which make it possible to calculate average sound levels at a specific distance from a traffic route or the edge of a particular area on the basis of specific data on the size of the area concerned, type of industry involved, volume and composition of traffic, intervals between trains, speed, route characteristics etc.
To ensure that local residents are not subjected to aircraft noise on an excessive scale and to guarantee the implementation of appropriate noise abatement measures, noise abatement zones for airfields and airports are designated in Germany on the basis of the Aircraft Noise Act Fluglärmgesetz. These zones encompass areas in which calculations based on the number of take-offs and landings, composition of air traffic and runway location indicate that specific sound levels (equivalent continuous sound level) are exceeded.
Immission standards either have general validity or apply to specific categories of area for which - depending on their sensitivity to noise - differing levels are specified. In the Federal Republic of Germany the area categories given in the ordinance concerning the use of land for construction purposes (Baunutzungsverordnung) are taken as the basis; it is assumed that a specific level of noise immission can be regarded as reasonable for each type of area.
The values laid down in guidelines and regulations were determined on the basis of empirically established links between sound level and noise nuisance, as well as the feasibility of enforcing them in local-authority development planning and transport planning.
4.3.2 Receptor-specific aspects
1. Human health
The effects of noise on human beings take the following forms:
- damage to hearing
- hindering of acoustic communication
- activation of the central and vegetative nervous systems
- impairment of performance
- nuisances
However, the extent of a noise nuisance is determined not just by the noise level but also by a variety of other factors (see above). In general, it can be said that average levels of 55 dB(A) at night and 65 dB(A) during the daytime represent the limits of acceptability. Noise levels in residential areas should not exceed the guide values specified in the German DIN standard 18005, namely 40 dB(A) at night and 50 dB(A) during the daytime. Sleep disturbances on account of noise are unlikely where the average level is below 35 dB(A) (recommended value for residential areas in respect of industrial noise, as laid down in Germany's Technical Instructions on Noise Abatement TA-Lärm: 35 dB(A)). Hearing is likely to be impaired when the noise level at permanently occupied workplaces is 85 dB(A) or more. Standards are laid down on the basis of nuisance or damage characteristics that can be readily objectivised, taking into account what is feasible and affordable from the planning viewpoint.
2. Conservation of fauna and flora
Noise essentially affects fauna in the following ways:
- Continuous noise disrupts acoustic communication and thus leads to changes in behaviour as regards mating, food gathering, warning signals and brood care, resulting in changes in natural biocoenoses in the area near the emission source.
- Individual noises, which may sometimes occur in conjunction with visual signals, can give rise to panic reactions, which at certain times - for example during territory-seeking or brood care - may result in habitats being permanently abandoned and reproduction endangered.
The following factors can be considered in assessing the impacts of noise immissions:
- species
- previous noise stresses (adaptation)
- type of noise (regularly recurring, sporadic etc.)
- visible changes in behaviour
- proximity of noise source to habitat
The usable supply of groundwater and surface water is defined as that proportion of the water suitable for a particular purpose which can be used in an economically efficient manner, which is available on average over a lengthy period and whose withdrawal is ecologically acceptable.
If the quantity of water taken from water resources exceeds the usable supply, vegetation will die off and streams and springs will run dry. The existence of opposing interests is likely to give rise to conflicts. The volume of groundwater that can be withdrawn is restricted on the one hand by the long-term need to ensure supplies of drinking water and process water and on the other hand by the demands of vegetation and agriculture.
The natural groundwater recharge rate (volume of water added to groundwater per unit of time and area) depends on geoecological conditions such as
- geological situation (above all permeability of surface layers, groundwater reservoirs)
- distribution of precipitation
- soil conditions
- vegetation
- other climatic factors
and on influences of anthropogenic origin, such as
- building (sealing of land)
- exposure of groundwater surfaces (e.g. as a result of gravel extraction)
- drainage measures (e.g. wells, channels, creation of large artificial lakes)
- soil compaction (e.g. caused by livestock, machinery, drainage)
- changes in vegetation.
Use of land for construction purposes plays an important role as regards the efficiency of the natural household, as the equilibrium between the individual components of the water balance is disturbed if open areas are increasingly sealed. Seepage is reduced; water accumulates in the body of receiving water (high water) and may cause evaporation to increase. The same happens if the soil is compacted as a result of construction measures or inappropriate tillage.
The withdrawal of large quantities of water adversely affects the living conditions of aquatic organisms, since it means that flow is reduced and the water temperature consequently rises. Changes in periodic flow rates as a result of impounding measures will adversely affect or destroy appropriate life forms and lower the groundwater level.
4.4.2 Receptor-specific aspects
1. Human health
The most important consideration is the need to meet man's quantitative requirements in respect of water for drinking and other purposes. Requirements depend on standard of living, consumption habits and water availability, which means that consumption levels vary widely.
It is relatively easy to determine per-capita drinking-water requirements (in litres). By contrast, the extent to which the available supply of water suitable for drinking has actually been ascertained varies greatly from one country to another. Renewal of resources is the subject of more or less valid estimates; it is often uncertain whether supplies can be replenished with water of equal quality.
Standards should always be based on the number of people involved, consideration of population trends and the fact that the water replenishing the supply does not necessarily have to fulfil the qualitative requirements. Ensuring of drinking-water supplies should be given priority over other forms of water use.
2. Natural household
Changes in the available water supply can influence the efficiency of the natural household. The function of the receiving water as part of a cohesive drainage system can be adversely affected by changes in flow. An increase in flow rate can lead to flooding, while a lower flow rate will reduce the removal of entrained substances.
The following negative impacts may occur:
- damage to agricultural irrigation systems
- damage as a result of dryness, harvest losses
- varying degrees of soil subsidence (changes in soil water balance)
- disruption of water supplies
3. Conservation of fauna and flora
The availability of water plays an important role in the development and preservation of a specific plant community. Major interference with the water balance thus leads directly to changes in biocoenoses caused by
- changes in groundwater level, particularly lowering of the groundwater level
- changes in the water level and flow in surface waters.
Region-specific environmental standards must be based on the requirements of the biocoenoses and the various organisms which they contain, above all with regard to
- minimum depth of surface waters
- minimum groundwater level
- periodicity of the available water supply
- minimum water quantity.
The natural quality of surface water and groundwater is influenced by the continuous introduction of substances and by continuously changing parameters. The introduction of substances into the water by man or nature is offset by self-purification processes, in which these substances are broken down by organisms which multiply in the water on a large scale. This functions only up to a specific system-dependent loading limit, above which the character of a body of water may undergo fundamental changes.
The concept of water quality is defined by
- the natural properties of a body of water or of the trophic level
- the water's current or potential use and the related quality requirements.
Physical effects (e.g. temperature increases) and chemical action may have such a sustained adverse impact on water quality that the specified quality requirements can subsequently be met only with the aid of technical treatment measures.
The differing quality requirements for various types of water use necessitate a variety of specific standards, in particular:
- standards for drinking water
- standards for water/bodies of water used for bathing
- standards for agricultural irrigation water
- standards for protecting aquatic organisms
- standards for industrial water supplies
- standards for livestock drinking water
For general purposes, i.e. without reference to a specific form of use, the condition of a body of water can be defined by means of
- its quality classification
- its temperature status.
The quality classes can be used for determining immission standards by stipulating that the requirements of a specific quality class are to be fulfilled at national or international level (see the section on environment legislation).
Division of a body of water into quality classes relates primarily to its pollution with organic substances that are biodegradable under oxygen-depletion conditions.
The graduated differences in the biological condition of flowing waters, occurring in the course of the self-purification process, are described in the saprobic system, which gives characteristic organisms or combinations of organisms for the various quality classes. The system is based on the observation that the communities of organisms found in polluted waters, and the frequency of the organisms' occurrence, differ from those in unpolluted waters. Although the saprobic system was developed for central European flowing waters, its basic principles can also be applied to conditions in other regions (see also WHO guidelines, various years).
It is relatively simple to determine water quality with the aid of indicator organisms and easy-to-record chemical parameters such as temperature, pH value and oxygen content. However, laboratory techniques - some of them complex - must be employed to ascertain the presence of more specific substances such as hydrocarbons. The chemical data provide only a rough idea of frequently occurring concentrations. Efforts are being made to achieve a realistic representation of the degree of water pollution with the aid of summation or collective parameters (BOD, COD). Use of these parameters simplifies matters, as it is virtually impossible to conduct a comprehensive analysis which covers the wide range of polluting compounds in its entirety. Some of the substances are treated in the section on chemical substances. Information on important EC directives on water quality, including the related parameters and standards, is contained in the section on EC environment legislation.
4.5.2 Receptor-specific aspects
1. Water quality/human health
Use of groundwater, spring water and surface water as drinking water and for purposes of personal hygiene is subject to specific quality requirements. The available raw water, particularly surface water, seldom fulfils these requirements. The substances naturally contained in the water, contamination caused by the activities of man and possible changes occurring during transportation mean that the water must be treated before it can be used.
Treatment of drinking water is intended on the one hand to preclude the possibility of health risks and on the other hand to ensure that the water meets certain sensory requirements, e.g. in terms of taste or odour.
The quality requirements to be fulfilled by bathing waters are intended to make sure that recreational activities such as swimming, water sports, fishing etc. do not involve any health risks. Apart from aesthetic standards covering aspects such as odour, clarity and colour, such requirements also relate to parameters representing health hazards, particularly the water's bacterial constituents.
2. Conservation of fauna and flora
Changes in natural water quality also affect the organisms found in aquatic systems, e.g. bacteria, algae and water plants. Water pollution may influence the natural living conditions in a variety of ways, for example through
- changes in oxygen content
- temperature changes
- changes in nutrient supply
- direct toxic effects.
The behaviour, reproduction and physiology of organisms may all be affected. Resistance to specific pollutants will result in these substances being passed on in the food chain. Harmful effects may threaten individual organisms or particular species. There is also a possibility of combination effects where a variety of different substances are present.
3. Preservation of the efficiency of the natural household
Permanent or at least long-term use of the natural resource represented by water simultaneously gives rise to changes in the water. In its function as a factor of production or a resource for use by man, water must thus be safeguarded on a long-term basis. Quality requirements exist for agricultural irrigation water and for water to be used in various sectors of industry. Such requirements should not be regarded as environmental standards in the true sense, however, as they focus primarily on the technical usability of water as a raw material. They can nevertheless offer certain pointers regarding the relevance of specific constituents or parameters (see WHO guidelines, particularly those on environmental engineering; WHO, 1990 etc.).
The soil forms the weathering layer of the Earth's solid crust. Its characteristics and development depend on the prevailing geological, topographic, climatic, hydrological and biological conditions. The term "soil quality" is generally taken as referring to a soil's suitability as a location for plants in the sense of its productivity. A frequently used synonym is the term "soil fertility", which describes the soil's ability to supply plants with nutrients, water, oxygen and warmth.
Apart from providing the basis for food production, soil conditions create the essential prerequisites for all terrestrial production of phytomass and thus form the foundation of virtually every food chain.
In addition to performing this vital role in safeguarding the existence of higher life forms, soils fulfil an important function within an ecosystem as
- filters and sinks for potential pollutants
- a habitat for soil flora and fauna
- the site of conversion and breakdown processes forming part of natural cycling systems.
The major types of impact on the soil can be classified as follows according to their basic nature:
1. Chemical changes result from
- application of fertilisers
- use of biocides and
- pollution caused by various immissions and depositions of anthropogenic origin (direct introduction of pollutants by wastes and waste materials, either solid (sanitary landfills, tips) or liquid (waste water, hydraulic fill); indirect introduction of pollutants following aerial transmission, through deposition of liquid or solid aerosols and introduction via precipitation).
2. Physical changes result from
- removal of soil (removal of individual layers, excavation)
- changes in the natural vegetation cover (land clearance, use of land for forestry)
- tillage (use of land for agriculture, terracing etc.).
3. Biological changes result from
- use of biocides and
- introduction of potential pollutants.
Changes in the water balance generally have direct effects on the chemical, physical and biological conditions in the soil.
The principal soil parameters are as follows:
- With regard to physical condition:
Structure, aggregate stability, pore volume and distribution, granulometric composition, density of mineral matter, density of organic matter and soil temperature- With regard to chemical condition:
Content and chemical composition of mineral and organic matter, acidity, ion exchange capacity, redox properties- With regard to biological condition:
Nature, composition and size of the edaphon
Analytical determination of soil condition, particularly of chemical properties and the reaction mechanisms and processes controlled by them, may present considerable problems in some respects.
Apart from determining the chemical composition of soils as mentioned above, the following key parameters are generally used for establishing soil quality:
- granulometric composition
- organic-matter content
- pH value
- cation exchange capacity
- base saturation
- field capacity/available field capacity
It should be borne in mind that soils yielding identical individual values are not necessarily of identical quality. Soil classifications (which vary depending on purpose and viewpoint) must be drawn upon in determining standards which take account of the diversity of soils and their optimum condition in each case.
Standards relate to soil quality in terms of suitability for agricultural use (soil evaluation), to erosion risks and to pollutant deposition. The Register of Substances contains more detailed information about substance-specific soil quality standards.
4.7 Agricultural and forestry land
Agricultural land provides the raw materials necessary to ensure a food supply. The amount of land needed per capita to meet staple-food requirements varies depending on geoecological conditions (particularly soil quality, available water supply and climate), eating habits and the level of development attained in agricultural engineering. The figure arrived at on the basis of a region's population and the above conditions can be taken as a standard for the amount of agricultural land required. In view of the influencing factors referred to above, standards of this type can be determined only on a region-specific basis.
Disregarding the ecological functions performed by forests, the minimum amount of forestry land required is determined by the population's requirements in terms of wood and other usable forest components (leisure, medicaments, plants/fruits etc.). It depends on geoecological conditions and local habits (e.g. fuel needs).
The availability of agricultural and forestry land is influenced in particular by
- changes in the purpose for which land is used (transforming forests into agricultural land, transforming agricultural and forestry land into areas for settlement, transport routes, industry, mining operations etc.);
- the damage done to the soil by pollutants, erosion, removal etc. as the direct or indirect consequence of other economic activities or minimally site-appropriate cultivation practised with a view to preserving the soil's usability in the long term.
In general, such standards for the minimum amount of agricultural land required take the form of empirical values applying to specific countries or regions. Depending on the conditions outlined above, the figure given may be many square kilometres (extensive pasture farming), roughly one square kilometre (shifting cultivation), one hectare (e.g. rice-growing) or less (horticulture). No corresponding figures are known to exist for forestry land.
4.8 Biotope conditions (special biotope functions)
This section covers biotope-related aspects not considered in connection with the environmental quality parameters previously discussed. In terms of composition and density, vegetation and fauna constitute a community (biocoenosis) which has developed over a lengthy period through the interaction of the relevant ecological factors and which occupies a more or less precisely defined habitat (biotope). An ecosystem consists of an indefinite number of biotopes exhibiting a specific form of interdependence.
The conditions to be met by an "intact" biotope are derived from the communities' requirements in terms of the environment necessary for the preservation of species. The major determining factors are
- biotope-specific minimum area
- interlinking of areas
- diversity of structure and species (to offset disturbing influences)
- absence of disturbances.
Scientific research has yielded findings on effect chains in ecosystems, the extent of changes caused by external influences and the biotope requirements of individual species (above all particular index species such as large fauna, birds and protected species) which make it possible to define area-specific "environmental standards". Every species (flora or fauna) forms part of a biotope, where it plays a (generally) indispensable role. If one element of a biotope is removed, both the composition and the functioning of the biotope will be changed or disrupted. Although there are no standards (in the strict sense) for biotope conditions that ensure preservation of fauna and flora, such standards can be formulated for specific regions on the basis of the characteristics of the region's typical biotopes. Certain attempts are being made to find a meaningful substitute by considering natural substance cycling systems and the energy cycle. Apart from the national protected status of specific areas, one pointer for determining the extent to which areas merit protection could be provided by information on the (potential) occurrence of protected species (e.g. species threatened with extinction). Particular attention must be drawn to the Washington Convention on International Trade in Endangered Species (see section on the international environment legislation) and Germany's Federal Ordinance on the Conservation of Species. However, the "red lists" are based only on the criteria of endangerment and rarity. Other criteria should also be taken into account, e.g. benefits and importance for the natural household or the need to preserve the diversity and characteristic features of the natural environment and the landscape. Measures to protect biotopes must be concretised in line with specific regional needs following analysis of relevant conventions to obtain information on particular species.
Alongside outward quality features such as weight and size (based on marketing strategies), general food quality criteria also include "internal" characteristics such as absence of pollutants, nutritional value and taste. In connection with environmental standards, food constituents can serve as yardsticks for the toxicological assessment or admissibility of pollutants and in particular of chemical aids in the environment. They thus have only an indirect bearing on the environmental impacts of specific projects. They can be used if necessary as a qualitative criterion in concrete environmental studies. Some of the existing standards are given in the information sheets forming part of the Register of Substances. Further information on food quality and the residue problem can be found in particular in the Ordinance on maximum quantities for pesticides and aflatoxins, the pesticide list (1990) compiled by the Biologische Bundesanstalt für Land- und Forstwirtschaft [Federal Biological Research Centre for Agriculture and Forestry] and the WHO Food Additives Series (various years). The major factors influencing the pollutant content of foods are
- the substances/pollutants contained in soil and irrigation water, either as natural constituents or introduced as a result of action by man
- the uptake of airborne pollutants
- the use of pesticides and fertilisers
- the use of drugs in animal production
- biogenic conversion products.
Pollutants in soil or on plants may have an indirect effect on man via the food chain. The accumulation processes that can occur in the food chain and the receptor-specific effect of substances mean that a food may contain extremely harmful pollutant concentrations without the growth of the original plant having been affected in any way.
Sometimes, however, pollutants can have adverse effects on plants' reproductive capacity and pest resistance.
The extent to which contamination of environmental compartments influences the pollutant content of foods depends on the individual crops' specific uptake rate in respect of the substances concerned (so-called "transfer factors"). Standards for environmental media generally do not take account of accumulation processes or synergistic and receptor-specific phenomena.