Soil contamination

Under soil contamination (also known as floor loading , soil pollution or soil contamination hereinafter) and the presence of the entry are organic or inorganic pollutants in the environmental medium soil understood. As with air and water pollution , a large part of the world's soil contamination has human causes such as immissions from traffic and industry , legal and illegal waste disposal , accidents with the release of pollutants or the spread of contaminated materials (some fertilizers and pesticides or sewage sludge ).

Contamination affects the properties and functions of the soil and thereby endangers all other components of the natural balance such as people , animals , plants or groundwater . All pollutants are more or less firmly bound in the soil. In many cases there is a long-term storage which, with constant entry, leads to an accumulation and thus to increasing damage. Soil remediation is theoretically possible, but due to the high time, labor and cost intensity it is often impossible to carry out in practice. For this reason, much soil damage caused by contamination, especially with heavy metals , is classified as irreversible.

Floors are in Germany since 1999 ( Federal Soil Protection Act ), in its status as a subject of protection equivalent to the environmental media air and water.

Terminology

The terms contamination, pollution, pollution and pollution are often used synonymously in the press and literature. When choosing words, however, the focus is mostly on human sources of pollution, for which all four options are applicable. In the case of a natural source of pollution, however, the use of the word “soil pollution” is generally avoided.

Natural pollution

Natural sources

Pollutants come from a variety of sources, some of which are of natural origin.

Geogenic base salary

Radioactivity and heavy metals occur naturally in the environment. They are therefore detectable in traces in all soils. This usually very low pollution is called the geogenic base salary or geogenic background . It is usually measured in the raw material not influenced by human activities (C horizon ). Depending on the starting material of the soil formation, the basic levels vary considerably. That is why there are tables in Germany with regionally differentiated information.

The geogenic base content of organic pollutants is always 0, as these are exclusively of artificial origin in significant quantities. (Minimum levels of some compounds that are possible as intermediate products in natural metabolic processes are close to the detection limit in the soil). The only exception are some petroleum constituents in the event of a natural escape of petroleum ( asphalt lakes ), e.g. B. in California or Trinidad .

volcanic eruptions

Volcanic eruptions are a natural factor that releases pollutants into the atmosphere , because large quantities of harmful substances such as sulfur dioxide are emitted during their eruptions (see also volcanic gas ). Although this effect has a verifiable global impact on precipitation and temperatures, it does not cause human acid rain , i.e. a permanent deterioration in rainwater quality due to air pollution .

Natural soil pollution areas

Some raw materials, especially rocks, naturally have higher basic contents. Examples would be the increased radioactivity in granite or the higher exposure to the heavy metals chromium, copper, nickel and zinc in some clay stones or magmatites . Regions with naturally elevated values are called natural soil pollution areas.

In particular ores near the surface , such as B. zinc blende , copper luster or lead luster in the Goslar area ( Harz ) cause a significant increase in the geogenic base content. In some rare cases there are also small areas in nature with heavy metal pollution that is toxic to plants. These are characterized by their own, sparse vegetation with specially adapted plants (natural calamine flora , heavy metal corridor) and people often served as indicators for ore deposits.

Human pollution

Human sources

Soil contamination with the secondary meaning “soil pollution” is caused by human activity, and the sources are extremely diverse. Important sources of contamination are:

Wastewater and exhaust air: Leakage of pollutants through unfiltered exhaust gases ( emissions ) or the discharge of polluted wastewater from industry, traffic or households. They lead to a supra-regional pollutant input via the air ( immissions ) or the water.

Targeted use: Concentrated application of pollutants associated with a specific purpose (e.g. DDT use against insects, use of chemical warfare agents such as Agent Orange , some pesticides).

Accidents and cases of damage: Unintentional release of pollutants in road traffic, in buildings, during industrial processes, on pipelines or during construction work (accidents, leaks, burst pipes, etc.).

Garbage disposal : illegal or legal dumping of garbage from which numerous pollutants can escape ( landfill , wild garbage disposal, etc.).

Stockpiles : Open or temporary storage of materials from heavy industry such as overburden , slag or ore.

Release of radioactivity : accidents or nuclear weapons tests .

Use of contaminated materials: Conscious or unconscious use of materials that are e.g. B. release pollutants into their environment through corrosion or abrasion (lead pipes for tap water, many color pigments and paints such as the historic postal yellow , leaded gasoline, etc.).

Side effect of land use : the application of less polluted materials to improve the soil , which accumulate pollutants with long-term input (some fertilizers (uranium and cadmium-containing phosphates) and pesticides (copper preparations), sewage sludge , ash application , etc.).

Anthropogenic pollution from heavy metals goes back to the beginnings of human metal processing and, in small areas, can be centuries or millennia old. In old mining regions such as the Ore Mountains or the Harz Mountains, contaminated areas from the Middle Ages can be found. However, a large part of the contamination can be traced back to the last two centuries from the beginning of the industrial revolution.

Organic pollutants and cyanides have been released almost without exception in the past 150 years (beginning of the chemical industry around 1850), despite their worldwide traceability and major environmental damage.

Exposure to released radionucleotides largely originates from processes of the so-called atomic age (around 1945).

Background pollution

The average pollution of a region with pollutants, i.e. the sum of natural sources and the average input from humans, is called the background pollution . The contents are determined by analyzing the topsoil and subsoil material (A and B horizon), whereby a statistically meaningful amount of sample points must be available for each region. The background pollution of the counties and regions in Germany is available in the form of tables.

The proportion of human inputs in the total value increases depending on the level of soil pollution. In the case of organic pollutants, it is (almost) always 100%, since these naturally do not occur. A direct comparison of the geogenic base content and the background content is not possible, since the values are determined at different soil depths, but the increase in the background pollution compared to the geogenic base content is a measure of the level of human influence.

As a rule, the background pollution in industrialized countries is (significantly) higher than the geogenic base content. In some rare cases, e.g. B. in natural soil pollution areas, but it can also be lower.

Selection of important soil pollutants

Inorganic pollutants

Heavy metals

A particularly important group of potential pollutants is made up of some heavy metals . These are defined by their density (> 5 g / cm³). When preparing soil reports in Germany, examinations of cadmium (Cd), chromium (Cr), mercury (Hg), nickel (Ni), lead (Pb) and (only for the protected plant) copper (Cu) and zinc (Zn) required by law. In addition, cobalt (Co) and thallium (Tl) are classified as relevant in terms of human toxicity in the Federal Soil Protection Act .

Many heavy metals are non-toxic [e.g. B. iron (Fe), manganese (Mn) or tungsten (W)] or, like indium (In), are only above the detection limit in exceptional cases.

Heavy metals occur naturally. However, much of the global contamination has human causes, primarily mining , the metal industry ( production and processing ) and transport (e.g. leaded gasoline). The use of products containing heavy metals is generally widespread.

Heavy metals such as rhodium (Rh), platinum (Pt) or palladium (Pd), which were used in vehicle catalytic converters , have recently been increasingly found in soils due to the massive use of this technology. At the roadside z. B. for rhodium an increase from 0.4 µg / kg to 20 µg / kg can be found. Whether and to what extent these concentrations pose a risk has not yet been investigated.

Cyanide

Cyanides (compounds with the anion CN-) have no geogenic base content , since measurable quantities do not occur naturally in the soil. They arise as by-products in some very specific industrial processes ( tar and bitumen industry , coking plants ) or are used ( prohibited in the EU since 2010) in gold and silver extraction.

Other inorganic substances

When preparing soil reports, the sample must be examined for the semi-metal arsenic (As). The light metal beryllium (Be) and the semi-metals antimony (Sb) and selenium (Se) are also classified as relevant to human toxicity in the Federal Soil Protection Act . Beryllium is used in aircraft technology, while antimony is typical of military sources ( ammunition ).

Soil damage caused by excessively high salt content is a special case. This form of soil pollution can only be viewed as a form of contamination if it is caused by an active supply of salt (road salt ). Worldwide, however, natural salinization processes, which do not fall under the term soil contamination and are often intensified by misuse, play a much more important role (see salinization ).

acid rain

Gases such as nitrogen oxides or sulfur dioxide and various acids such as sulfuric acid or hydrochloric acid are relevant . Many of these substances are released by traffic and industry and lead, among other things, to a decrease in the pH value of rainwater (acid rain). This changes the soil chemistry over time and can, for. B. contribute to the release of heavy metals.

radioactivity

The term contamination is used almost exclusively for contamination with radiation sources such as uranium or radioactive isotopes (e.g. iodine 131, cesium 134).

Organic pollutants

All organic pollutants with the exception of some mineral oil hydrocarbons (naturally leaking petroleum) are of artificial origin and therefore do not occur naturally. The list is exhausting because humanity has produced and released a large number of harmful compounds. In the following, only the most important groups with their most important representatives and sources are presented.

Mineral oil hydrocarbons (MKWs)

Compounds that are composed only of carbon and hydrogen ( hydrocarbons ) and are based on petroleum . These include numerous fuels such as diesel , gasoline or heating oil . The main pollution zones are therefore roadsides, petrol stations , workshops or oil refineries .

The English term TPH (total petroleum hydrocarbons) is sometimes used in reports.

Highly volatile chlorinated hydrocarbons (LCKWs)

Group of pollutants that have been produced and used in large quantities for years, primarily as cleaning agents and solvents. Because of their persistence and environmental pollution, most of them are now banned or severely restricted in their use. The most important soil-damaging CHCs are trichloroethene , tetrachloroethene and dichloromethane . Even if these substances are highly volatile, they can be stored in large quantities in the soil for decades.

The English term chlorinated volatile organic compounds (CVOC or Cl-VOC) is sometimes used in expert reports.

BTEX aromatics

BTEX is the abbreviation for the aromatic hydrocarbons benzene , toluene , ethylbenzene and xylene . These pollutants are widespread as raw materials and by-products of industrial processes as well as components of numerous products (e.g. benzene in fuels), which is why they can almost always be detected in industrial estates and on roadsides.

Polycyclic Aromatic Hydrocarbons (PAH)

PAHs consist of at least two linked aromatic ring systems (benzene rings), which always lie in one plane. They arise in numerous processes, in particular the combustion of petroleum products, and can now be detected almost all over the world. In total there are several hundred different compounds, the two best known of which are naphthalene and benzo [ a ] pyrene . The PAHs are usually socialized with one another, so that many of them can be detected at the same time in a contaminated soil.

Since every single PAH requires its own analysis, standard tests only test for a few specific, particularly common substances in this group. In Germany, the values PAK-TVO (PAK-7, test for the seven PAHs specified in the Drinking Water Ordinance (TVO)) and PAK-EPA (PAK-16, test for the 16 PAHs specified in the BBodSchV) are common.

The abbreviation PAH (English: polycyclic aromatic hydrocarbons) is often used in expert reports.

Polychlorinated biphenyls (PCB)

PCBs are organic chlorine compounds that were used up until the 1980s and a. used as plasticizers. Because of their toxicity and persistence, they have been internationally banned since 2001 ( Stockholm Convention ). However, they are still detectable in soils around the world and in many countries they are a problem on old sites (legally referred to as contaminated sites in Germany).

Since each individual PCB requires its own analysis, standard tests only test for a few specific, particularly frequent connections. In Germany, according to the BBodSchV, this is the sum value PCB / 6 (∑PCB), i.e. the analysis of six particularly important substances in the group.

Polychlorinated dibenzodioxins and furans (PCDD / F)

PCDD and PCDF , often simply abbreviated as dioxins and furans, are two groups of chemically similar chlorinated organic compounds. They are generally very persistent and traces can be detected in soils around the world.

They are not produced in a targeted manner, but rather arise as by-products in many industrial processes, including paper production (chlorine bleaching). All processes involving heat in the presence of hydrocarbon and chlorine compounds are also important. Building fires and waste incineration without filter systems are therefore important sources .

Military contaminants

Pollutants from military use can be found on military training areas , on former battlefields and bomb targets as well as at locations of the arms industry . Many contaminants such as explosives ( TNT , mercury, etc.) or chemical weapons are clearly of military origin. Heavy metals (antimony, lead, uranium , mercury, etc.) are also spread over large areas via ammunition and explosive devices .

Pesticides

From around the middle of the 20th century, numerous chemical compounds were developed for use in crop protection . Many of these agents, currently around 250 different active ingredients are approved in Germany, are relatively briefly degradable in the soil (a few weeks to months). However, the degradation behavior in the soil is subject to increasing observation and control, also due to experiences with increasing environmental damage in the course of the 20th century. It is now an integral part of the approval process.

Many persistent connections have now lost their approval in Germany, e.g. B. DDT since 1972, lindane about since 1984 or atrazine since 1991, but are still detectable in soils and z. Some still in use internationally.

For some time now, copper-based biological pesticides have also received special attention, as the heavy metal copper that is introduced is irreversibly accumulated in the soil.

Plastics

Most of the plastic waste (including microplastics ) that enters the environment ends up in the soil. According to a study by the Eidgenössische Materialprüfungs- und Forschungsanstalt in Switzerland in 2018, 74 percent of tire wear reached the ground within 5 meters of the road, 22 percent flowed into surface water and the remaining 4 percent into soils further away.

Environmental impact

Behavior in soil

All pollutants are more or less firmly bound in the soil (buffer, filter and storage function of the soil). Depending on how strong this bond is, they can be stored in it or leave it again (volatilization, absorption by plants, leaching into the groundwater). In addition, all organic pollutants and cyanides are degradable, even if some of them are highly resistant (persistent). So their content slowly decreases over time due to chemical decomposition or microbiological degradation. Inorganic pollutants (heavy metals, semi-metals and radionucleotides), on the other hand, are generally not degradable.

If the sum of the inputs is higher than that of the discharges, there is an accumulation in the soil. A great many pollutants, especially heavy metals, show this property, which is why most of the soils contaminated by them endanger their environment in the long term. In addition, soils are therefore also a reliable archive that stores traces of almost every form of use and immission (in some cases over millennia).

A classic example is lead contamination from leaded gasoline in road traffic. This is now banned almost worldwide (in Germany since 1988). The lead pollution of the roadsides due to this fuel is still detectable.

Contaminated soil is not only a source of risk locally, it can also be carried over to other regions:

Dust deposition: displacement of contaminated material due to wind erosion . Typical are a plume-like load increase emanating from a source along the main wind direction and a significantly higher concentration of pollutants in the top soil layer. Depending on wind strength, regionally rather limited.
Floods : displacement of contaminated material due to water erosion . Typical are an accumulation along rivers (the contents tend to rise downstream), a relatively homogeneous pollution of all affected sedimentation layers and a wide occurrence of many different pollutants. Long-term spread of the contaminated area into the sea over great distances.

Damage to the environment

According to the Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) § 2 (6), pollutants are “substances and preparations that are capable of damaging the functions of the soil due to their harmfulness to health , their longevity or bioavailability in the soil or due to other properties and their concentration or other dangers. ”Many of them can accumulate in the food chain. In the animal and human organism, they are primarily stored in the liver .

Some heavy metals are among the trace elements that are essential for living things in small quantities. Of the 13 metals relevant in the BBodSchG, these are Co, Cu, Se and Zn for plants and As, Cu, Cr, Cu, Ni, Se and Zn for animals. With the exception of Zn for animals, all of them become potentially toxic if their limit values are exceeded . Toxins without physiological use are Be, Cd, Hg, Pb, Sb and Ta as well as all organic pollutants, cyanides and radionucleotides.

It is often the case that soil contamination is present long before there is any visible damage. In these cases, however, an impairment of the soil functions and a hazard to other environmental media has often already occurred. Increasing heavy metal contamination of forage or food crops or the leaching of pollutants into drinking water can often only be confirmed by laboratory analyzes. For this reason, soil contamination is viewed as risky and often goes unnoticed for years.

Pollutants directly damage the soil by affecting or killing soil life . This is a serious intervention in the soil, which is manifested, among other things, in the mineralization of nutrients and the decrease in species living in it. It is thus restricted in one of its main functions as a "living space". The entry of copper in particular is critical for microorganisms as this element is biocidal . Earthworms are very sensitive to even the smallest increases in the copper content. Since copper cannot be washed out and broken down, a permanent entry leads to an irreversible destruction of the soil life. This is a particular problem in old wine-growing regions , since pesticides containing copper have been known in viticulture since ancient times .

Plants can suffer from stunted growth due to pollutants in the soil or be completely prevented from settling on an area. Many contaminants hinder the rooting of the soil due to their plant toxicity. Polluted areas can often be identified indirectly in Germany if they show only sparse vegetation even after years of fallow. Trees may be completely absent or limited to a few specimens of the very tolerant (but also small) birch trees . Under normal circumstances, a lack of use in Central Europe leads to dense forest formation within a few years. Types of natural heavy metal flora (Galmeiflora) have meanwhile found a wide distribution through anthropogenically polluted locations. Their presence often indicates high levels of heavy metals in the soil.

Animals and humans can suffer numerous possible health problems through contact with soil pollutants. In addition to direct toxicity, long-term damage can also be considered. Many contaminants damage organs or body functions, are carcinogenic , affect reproduction or are mutagenic . The relevant risks depend heavily on the pollutants present in the soil.

Classification of the hazard potential

In order to determine the hazard potential of an area, a soil report is required in Germany. The process is specified in the Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) and essentially consists of four factors:

Protected asset - which environmental medium is being considered?

Pollutants in the soil can affect the air, plants, animals and people, other soils and bodies of water, including groundwater. In the BBodSchV, the protected objects of people / direct contact, useful plants, groundwater and soil are defined.

People and animals can be directly endangered by contaminated soil through breathing, swallowing (especially small children) and skin contact. In the case of (useful) plants, contamination occurs via dirt (adhering soil) or via the roots. This endangers the plants themselves in their growth, but also indirectly humans (food) and animals (fodder). The groundwater can be polluted through leaching and erosion. Soils are threatened by direct entry or relocation of contaminated material.

As a result, the pathways to be taken into account differ depending on the subject to be protected. Accordingly, the subject of protection under consideration determines which pollutants have to be examined, which analysis method is to be used and how high the limit values are (BBodSchV). For example, the copper content of a soil is investigated in the case of the protected asset of useful plants, but not for the protected asset of humans / direct contact.

Exposure - How much is a protected item exposed to the pollutant?

The risk from contaminated soil depends largely on how much contact (exposure) a protected property has with it. If contaminated layers are half a meter below the surface, direct human contact is unlikely. Entries into the groundwater or uptake by plants are quite possible. When classifying the hazard potential, not only the type and amount of the pollutants present, but also their location in the soil must be taken into account.

Land use has a significant influence on exposure. Therefore, in the BBodSchV, sub-groups with their own specifications are formed for the individual protected goods, such as playgrounds, residential areas, parks and commercial space (with increasing permissible values) for the protected goods human / direct contact.

Pollutant - which pollutant is present?

Every substance can be potentially damaging from a certain concentration (dose-effect principle). In Germany, therefore, various laws and ordinances such as the BBodSchV (Appendix 2) stipulate limit values , the level of which depends on the substance, the land use and the protected property under consideration. They can range from a few ng / kg soil (dioxins) to several g / kg soil ( table salt ). For example, they are 200 mg / kg DM in playgrounds, 400 mg / kg DM in residential areas, 1,000 mg / kg DM in parks and other areas for lead (human protection). Leisure facilities and 2,000 mg / kg DM on industrial and commercial properties.

Concentration and availability - How high is the pollutant content and how mobile or available is it?

In order to determine the possible harmful potential of a substance, its concentration is determined. Depending on the subject to be protected, this can be the total content or the available content (a distinction is made between mobilisable, exchangeable and water-soluble). The analysis methods to be used are stipulated by law (BBodSchV Anh 1 (3)).

Reversibility and countermeasures

The reversibility of soil pollution depends heavily on the type of contamination. In theory, it is theoretically possible to remove all pollutants using various soil remediation methods. However, since renovations are generally extremely complex and expensive, they can only be carried out on a small scale in practice. This limits their applicability and their area coverage considerably.

Organic pollutants are all biodegradable or chemically degradable, even if some of them have a high persistence. Contamination with them is therefore considered to be reversible in the medium term, especially if soil remediation methods are used as a support. However, the larger the affected areas and the more persistent the pollutants are, the more expensive, difficult and tedious cleaning will be. As a result, many soils polluted with organic pollutants are practically irreversibly polluted. This means that their functions cannot be regained within the next generations.

Heavy metals and radioactive elements are not degradable in the soil and are very firmly bound. Without an active intervention by a soil remediation process, their content remains the same or increases further. If there are also methods for cleaning, these cannot be used over a large area. The global increase in pollution with the associated soil damage must therefore be viewed as irreversible. Even extensive damage caused by acid rain cannot be reversed once the soil pH falls below a certain level.

Since the remediation of soiled areas is extremely tedious or even impossible, the best means of combating soil contamination is to avoid it ( soil protection ).

In addition to a complete rehabilitation of contaminated areas (decontamination), so-called safety and restriction measures are permissible according to BBodSchV § 5, which "ensure that the pollutants remaining in the soil or in contaminated sites do not permanently pose any dangers, significant disadvantages or significant nuisances for the individual or the General public arise. ”Under certain circumstances, these are covers or seals that fix the pollutants for the time being. In some cases, a change in land use is sufficient to adequately ensure the security of other environmental media.

Statutory Regulations

Germany

Direct laws for the protection of soils are the Federal Soil Protection Act (BBodSchG), the Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) and the soil protection laws of the federal states.

In addition, all legal measures for environmental protection also have an indirect effect on the protection of soils, such as the regulations of waste law , water and air protection , fertilizer and plant protection law or construction planning and building regulations .

The often used term contaminated site , according to BBodSchG § 2, refers to old deposits (waste disposal) and old sites (contaminated operational areas) that must have arisen before January 1, 1999 (when the BBodSchG came into force). According to the law, all contamination occurring after this date falls under the term “harmful soil change” and is legally treated differently.

literature

H.-P. Blume: "Handbook of Soil Protection", Wiley-VCH Verlag GmbH & Co. KGaA; 3. Edition, 2007, ISBN 9783527321247
H.-P. Blume, P. Felix-Henningsen, WR Fischer: Handbook of soil science. Ecomed Verlag, Landsberg 2002, ISBN 3-609-72232-0 .
Winfried EH Blum: Soil science in brief. (Hirts index books) Borntraeger, Berlin / Stuttgart 2006, ISBN 3-443-03103-X .
F. Scheffer, P. Schachtschabel: Textbook of soil science. Spectrum Academic Publishing House. 15th edition, 2002, ISBN 3-8274-1324-9 .
G. Hintermaier-Erhard, W. Zech: Dictionary of soil science. Enke 1997, ISBN 3-432-29971-0 .
H. Kuntze, G. Roeschmann, G. Schwerdtfeger: Soil science. UTB, Stuttgart 1994, ISBN 3-8252-8076-4 .

Web links

Federal Soil Protection and Contaminated Sites Ordinance
Federal Soil Protection Act
planet e. : Littered and contaminated - soils in danger (documentary, 28 min., 2019)

Individual evidence

^ Uranium in soil and water, brochure of the Federal Environment Agency, http://www.uba.de/uba-info-medien/4336.html , accessed on August 20, 2018.
↑ Delphine Kawecki, Bernd Nowack: Polymer-Specific Modeling of the Environmental Emissions of Seven Commodity Plastics As Macro- and Microplastics. In: Environmental Science & Technology . 2019, doi : 10.1021 / acs.est.9b02900 .
↑ Cornelia Zogg: Micro-rubber. In: empa.ch. November 14, 2019, accessed November 14, 2019 .
↑ Ramona Sieber, Delphine Kawecki, Bernd Nowack: Dynamic probabilistic material flow analysis of rubber release from tires into the environment. In: Environmental Pollution. 2019, p. 113573, doi : 10.1016 / j.envpol.2019.113573 .
^ Bruno Streit: Effects of High Copper Concentrations on Soil Invertebrates (Earthworms and Oribatid Mites): Experimental Results and a Model. In: Oecologia (Berlin). Vol. 64, No. 3, 1984, pp. 381-388, doi : 10.1007 / BF00379137 , JSTOR 4217476 .

[1] Uranium in soil and water, brochure of the Federal Environment Agency, http://www.uba.de/uba-info-medien/4336.html , accessed on August 20, 2018.

[DOI10.1021/acs.est.9b02900-2] Delphine Kawecki, Bernd Nowack: Polymer-Specific Modeling of the Environmental Emissions of Seven Commodity Plastics As Macro- and Microplastics. In: Environmental Science & Technology . 2019, doi : 10.1021 / acs.est.9b02900 .

[3] Cornelia Zogg: Micro-rubber. In: empa.ch. November 14, 2019, accessed November 14, 2019 .

[DOI10.1016/j.envpol.2019.113573-4] Ramona Sieber, Delphine Kawecki, Bernd Nowack: Dynamic probabilistic material flow analysis of rubber release from tires into the environment. In: Environmental Pollution. 2019, p. 113573, doi : 10.1016 / j.envpol.2019.113573 .

[5] Bruno Streit: Effects of High Copper Concentrations on Soil Invertebrates (Earthworms and Oribatid Mites): Experimental Results and a Model. In: Oecologia (Berlin). Vol. 64, No. 3, 1984, pp. 381-388, doi : 10.1007 / BF00379137 , JSTOR 4217476 .