*2.1.2.1 Lead*

*Biosensors for Environmental Monitoring*

hydrolyzed solution.

*2.1.1.2 Copper*

nated food.

*2.1.1.3 Zinc*

*2.1.1.4 Cobalt*

heavy beer drinkers [11].

vital importance it has for most living organisms, iron is potentially toxic at high concentrations. The effect of iron on aquatic organisms and their habitats is mostly indirect. Combined direct and indirect effects of contamination of the aquatic environment cause a decrease in biodiversity and number of fish. In aqueous solu-

hydrolyzed (hydrolysis starts at pH 1). Hydrolysis of Fe(III) ions depends on the type of ionic environment, temperature, and the presence of other substances. The results of the researches show that the most important chemical types are found in

Copper is a microelement of outstanding biological importance and is part of essential metabolic pathways. Copper ions play a key role in active centers of oxidoreductases, such as superoxide dismutase (Cu, Zn-SOD), [5], an enzyme important for maintaining a low level of free radicals in the cell, thus protecting biomolecules

Copper deficiency can cause anemia, because insufficient amount of copper causes poor absorption of iron, reducing the number of red blood cells. The lack of copper also reduces the amount of white blood cells and therefore the resistance of the organism to diseases. In general, copper is not considered to be a major ecotoxicological problem, but its widespread distribution and exposure to exhaust gases are certainly the reasons why copper is involved in the structuring of ecosystems.

being the most common. The most mobile forms of copper are Cu2+ and CuOH+

In the aqueous environment, copper is found in three basic forms, as suspended, colloidal, and dissolved. The accumulation of copper in the aquatic environment results in the primary exposure of aquatic organisms. Aquatic organisms can accumulate dissolved copper by direct absorption through the body surface, while colloidal forms of this metal are introduced into the body by ingesting contami-

Zinc participates in the structure of many enzymes and is an essential element. It is attached to insulin and plays a significant role in the metabolism of nucleic acids and amino acids, DNA replication, and gene expression. However, like all other essential metals, zinc in higher concentrations is toxic to living organisms. Zinc can bioaccumulate in fish, and the degree of bioaccumulation usually depends on the exposure mode, as well as the conditions prevailing in the observed aquatic environment. Conditions that may affect the toxicity of zinc (but also other heavy metals) in the aquatic environment are the content of Ca and Mg, the pH of water, the content of the hydroxide (alkalinity), and the content of dissolved natural

The required amount of cobalt in the body is about 5 mg for vitamin B12 to avoid anemia. In general, cobalt has low toxicity. Gastrointestinal (digestive tract) absorption of soluble cobalt compounds is estimated to be 25%. However, cobalt is toxic to humans. When cobalt has been used as an additive in beer (for foam stabilization), severe biventricular heart failure and a high mortality rate were observed in

3+, which is quite

, Cu2+, and Cu3+, with the Cu2+ form

.

tions, the Fe3+ ion is in the form of the aqua complex, Fe(H2O)6

such as proteins and lipids from the pathological conditions.

Copper is found in three oxidation states, Cu+

organic matter, i.e., humic substances.

**142**

Lead in the environment mainly comes from anthropogenic sources such as combustion of fossil fuels, landfills and fires at landfills, waste industrial sludges, phosphate-based fertilizers, pesticides, and exhaust gases from vehicles.

It is found in the form of sulphates, sulphides, and carbonates. It is considered the leading environmental pollutant and is increasingly endangering the living world, especially the surrounding areas of large industrial plants, frequent roads, and large cities.

The intensity of the adoption of lead depends on its concentrations in soil, soil pH, organic matter content, ratio of cations and anions, and other environmental factors. Human is exposed to toxic effects of lead by consuming food and water that are contaminated with this heavy metal but also by inhaling particulate matter with lead content. Absorption over the skin is only possible for tetraethyl and tetramethyl lead. Lead is rapidly absorbed into the bloodstream and binds to red blood cells in the form of Pb2+, and via blood about 90% is deposited in the bones in the form of Pb3(PO4)2. In the case of acidosis (increased acidity), the mobility of lead from the bones in the form of Pb2+ which has a toxic effect on the central nervous, circulatory, and immunological systems and kidneys can occur. [10]
