From the viewpoint of threats to the soil-and-aquatic environment, hazards include currently operated industrial waste landfills as well as historical waste dump sites identifiable through archival reference material studies. With regard to this particular aspect, recognising the specificity of the “ZACHEM” S.A. Chemical Plant in Bydgoszcz will be of particular importance, both in terms of production variability and technological methods applied. In analysing the chemical compound of the Plant’s manufacturing profile, the firm link between the production type and contamination seeping into the soil-and-aquatic environment – especially into Quaternary aquifer groundwaters – stands out.

Six groups of potentially contaminating substances have been identified in the soil-and-aquatic environment in the “Zielona” waste landfill complex:

• Phenol, including derivatives and decomposition products in the aqueous environment,

• Chlorophenols associated with fungicide compound, and (to a lesser extent) pesticide and insecticide production,

• Phenolic pitch (i.e. amorphous waste) residue associated directly with the production of phenol and “Rezokol” glue (phenol-formaldehyde resin),

• Sodium sulphite – waste generated during phenol production, and therefore heavily contaminated with the substance,

• Glycols, their origin associated with post-production waste or heat exchanger manufacturing,

• Dyestuffs and dye intermediates directly associated with the Plant’s on-site pigment and dye manufacturing operations; this group primarily includes substances such as aniline and chloroaniline.

Group classification was determined by aspects such as (1) primary products, derivatives and production waste included, and (2) similar internal structure of chemical compounds, governing the substance’s behaviour in the aquifer. Of all chemicals listed, phenol is the one mainly responsible for organic contamination in the soil-and-aquatic environment of the “Zielona” waste landfill complex zone.

Phenol is also known as hydroxybenzene (C₆H₅OH), the simplest compound of the phenols group – organic compounds with a hydroxyl groups (OH-) attached directly to aromatic ring carbon atoms.

The substance usually presents as white or colourless crystalline matter or pale pink fluid, all browning in contact with ambient air. A sweetish, tarry taste and fragrance are its landmark, the smell perceptible in ambient air at low concentrations of 9.5 to 16 ppb (parts per billion); in water, the taste of phenol is perceptible even below concentrations of 2 ppb (parts per billion).

The decomposition of phenol in soil is considerably varied, depending on prevailing oxidation and reduction conditions. In slightly alkaline clay sandy clay, it takes phenol 4.1 days to semi-decompose; in acidic clays, on the other hand, that parameter increases to 23 days. Once these periods are over, half the phenolic pollutant mass remains in the environment. This is not to say that the environment self-cleanses in 3 weeks, however. In case of the “Zielona” industrial waste landfill complex of the former “ZACHEM” S.A. Chemical Plant in Bydgoszcz, the original phenol deposit volume reaches several dozens of tonnes. Consequently, despite its relatively short semi-decomposing time, phenol will remain in local groundwater over successive years due to the uninterrupted and intense process of waste leaching from the landfill.

Phenol deposited in the “Zielona” industrial waste landfill complex of the former “ZACHEM” S.A. Chemical Plant in Bydgoszcz is directly associated with the production of phenol and intermediates, such as phenol-formaldehyde glues. Partially exposed on the landfill, recrystallised and phenol-contaminated waste is a real health hazard. Phenol is highly toxic. Indeed, it is believed to cause genetic defects and induce gene mutations, the lethal dose tested on rats reaching 340 mg/kg (oral ingestion), 660 mg/kg (skin contact) and ambient air concentration rates above 900 mg/m³ if inhaled over a period of 8 hours.

Apart from phenol – considered the main source of organic pollution – chlorophenols and glycols have been identified as well.

Chlorophenol (C₆H₅ClO) is any of simplest organochlorine compounds containing one or more covalent-bond chlorine atoms. The substance presents as pale amber liquid with mildly phenolic odour. The smell is perceptible in ambient air at a concentration of 0.088 to 20 ppb (parts per billion); in water, the taste is perceptible at 0.14 ppb. Due to their toxicity, chlorophenols are hazardous to the health and life of organisms (including humans). They have been found to be carcinogenic and mutagenic, even at low concentrations. This is why it is essential to monitor their concentrations in the soil-and-aquatic environment in the immediate vicinity of the “Zielona” waste landfill complex.

Glycols or vicinal diols (R(OH)₂) are organic chemical compounds – alcohols with hydroxyl groups on adjacent carbon atoms. The reactivity of glycols resembles that of other alcohols. Their primary form apart, they are found in the soil-and-aquatic environment in reaction product form. Cyclic glycol synthesis generates trans- or cis- products, depending on the method of choice. KMnO₄ or OsO₄ oxidation produces cis-diols; epoxy compound hydrolysis produces trans-isomers.

The name “glycol” is also commonly used to reference (ethyl glycol) 1,2-dihydroxyethane. This is the simplest diol – a polyhydroxy alcohol. This substance presents as a colourless, odourless thick fluid with a sweetish aftertaste.