**1. Introduction**

The quality of human life depends on the chemical composition of the environment, including food, water, and many other factors necessary for life. The development of human society, however, has brought substantial increases in ecological problems and contamination of the environment [1]. Some parts of the environment (e.g. atmosphere and hydrosphere) are able to partially remove the contaminants or to disperse them over wide areas and eliminate their potentially ecotoxic effects. The pedosphere, however, cannot, and important "hot-spots" with extremely high levels of a variety of pollutants have developed concurrently with human society in recent decades [2]. Soil is one of the most important factors for terrestrial life through the production of food, so its degradation could reduce the diversity or abundance of various valuable organisms necessary for maintaining balanced ecological functions [3].

Understanding the impact of pollution on important soil processes, where soil organisms play key roles, requires observing not only the quantity of the pollutants in a system, but also their qualitative effects and ability to change the environmental conditions for soil biota [4]. Various approaches using different soil communities were thus developed for biomonitoring poten‐ tially endangered ecosystems. The wide variety of communities, either directly in the soil or above it, tightly linked to soil processes makes the selection of an appropriate bioindicator challenging. Soil mesofauna, composed of various invertebrate communities, are the most suitable [5]. Soil invertebrate communities are able to buffer short-term resource shortages without significant losses in abundance or diversity [6], but they also have relatively rapid and identifiable reactions to contamination, because they are integrators of the physical, chemical, and biological properties related to their food resources [5]. Within the mesofauna, soil nematodes [7], springtails [8], and mites [9] have been considered for use as reliable bioindi‐ cators. Nematodes may be the most promising candidates for systems of bioindication, because more information on their taxonomy and ecology [10] is available than for other animal groups.

#### **1.1. Nematodes as bioindicators**

Nematodes are amongst the most abundant multicellular organisms in nearly all soil ecosys‐ tems, occupying key positions at most trophic levels in the soil food web [11]. They are involved in organic matter mineralisation, plant growth, and crop productivity by their regulation of detritivore populations and thus contribute to the stability of the food web [12, 13, 14]. Their life cycles have been widely studied, partly because some taxa are pests [15]. The nematode *Caenorhabditis elegans* is a key model for genetic studies, which could significantly improve the bioindicating potential of nematodes on molecular and gene-expression levels.

The introduction of the maturity index by [7], one of the best-known indicators of soil health [15], was a crucial breakthrough in nematode bioindication. Nematodes are classified in this system along a coloniser-persister (c-p) continuum and assigned to c-p groups ranging from 1 (colonisers) to 5 (persisters). Similar to the r/K dichotomy, colonisers are characteristic of early successional stages, and persisters are found mainly in more developed and complex ecosystems. The advantage of the c-p system is that nematodes only need to be identified to the generic level, which does not affect the resolution of the indication.

Several other derived or new ecological indices have been developed from the maturity index. Ferris et al. [11] provided a framework for determining the enrichment (enrichment index, EI) and structure (structure index, SI) of food webs based on the relative weighted abundance of the functional guilds of nematodes. A matrix of feeding habits, with life history characteristics embodied in the c-p classification, is used to enhance the resolution of nematode analyses and to connect the functional groups with the enrichment and structure of the food web and channels of decomposition.

We applied these approaches at two locations, Kovohuty JSC Krompachy and Slovak Mag‐ nesite Works JSC Jelšava, with soils contaminated by dust fallout containing high amounts of potential ecotoxic elements. The levels of contamination at these sites have been analytically determined, but little is known about the soil communities and their interactions or about the general health of the soil. The aims of this study were thus to improve our knowledge of the polluted sites and to better understand the biotic processes under environmental pressure and the consequences of industrial pollution for soil food chains.

The specific objectives were

**1. Introduction**

24 Emerging Pollutants in the Environment - Current and Further Implications

**1.1. Nematodes as bioindicators**

The quality of human life depends on the chemical composition of the environment, including food, water, and many other factors necessary for life. The development of human society, however, has brought substantial increases in ecological problems and contamination of the environment [1]. Some parts of the environment (e.g. atmosphere and hydrosphere) are able to partially remove the contaminants or to disperse them over wide areas and eliminate their potentially ecotoxic effects. The pedosphere, however, cannot, and important "hot-spots" with extremely high levels of a variety of pollutants have developed concurrently with human society in recent decades [2]. Soil is one of the most important factors for terrestrial life through the production of food, so its degradation could reduce the diversity or abundance of various

Understanding the impact of pollution on important soil processes, where soil organisms play key roles, requires observing not only the quantity of the pollutants in a system, but also their qualitative effects and ability to change the environmental conditions for soil biota [4]. Various approaches using different soil communities were thus developed for biomonitoring poten‐ tially endangered ecosystems. The wide variety of communities, either directly in the soil or above it, tightly linked to soil processes makes the selection of an appropriate bioindicator challenging. Soil mesofauna, composed of various invertebrate communities, are the most suitable [5]. Soil invertebrate communities are able to buffer short-term resource shortages without significant losses in abundance or diversity [6], but they also have relatively rapid and identifiable reactions to contamination, because they are integrators of the physical, chemical, and biological properties related to their food resources [5]. Within the mesofauna, soil nematodes [7], springtails [8], and mites [9] have been considered for use as reliable bioindi‐ cators. Nematodes may be the most promising candidates for systems of bioindication, because more information on their taxonomy and ecology [10] is available than for other animal groups.

Nematodes are amongst the most abundant multicellular organisms in nearly all soil ecosys‐ tems, occupying key positions at most trophic levels in the soil food web [11]. They are involved in organic matter mineralisation, plant growth, and crop productivity by their regulation of detritivore populations and thus contribute to the stability of the food web [12, 13, 14]. Their life cycles have been widely studied, partly because some taxa are pests [15]. The nematode *Caenorhabditis elegans* is a key model for genetic studies, which could significantly improve the

The introduction of the maturity index by [7], one of the best-known indicators of soil health [15], was a crucial breakthrough in nematode bioindication. Nematodes are classified in this system along a coloniser-persister (c-p) continuum and assigned to c-p groups ranging from 1 (colonisers) to 5 (persisters). Similar to the r/K dichotomy, colonisers are characteristic of early successional stages, and persisters are found mainly in more developed and complex ecosystems. The advantage of the c-p system is that nematodes only need to be identified to

bioindicating potential of nematodes on molecular and gene-expression levels.

the generic level, which does not affect the resolution of the indication.

valuable organisms necessary for maintaining balanced ecological functions [3].


**Figure 1.** Maps of the study areas with indication of the emission source and sampling points (white arrows - K1-K4 for Krompachy, J1-J4 for Jelšava); prevailing winds are indicated in the compass rose.
