**7.2. Sodium and potassium**

**7. Salinity changes**

**7.1. Chlorides and sulphates**

be monitored.

388 Water Quality

logical years 2004–2006.

Water salinity is generally defined as the total content of the salts dissolved in water. In the case of storage reservoirs, usually the contents of chlorides, sulphates, potassium and sodium ions are determined in water. High salinity can be harmful to the environment and it should

The occurrence of chloride ions is common in the environment, including water. Their content in natural non-polluted water ranges from trace level to several hundred mg dm−3. They are also present in vegetation and in animals. The presence of chlorides in water is responsible for the increased rate of corrosion. Chlorides are also harmful to fresh water vegetation [7].

In the hydrological years 2004–2006, the monthly average concentration of chlorides in the reservoir was in the range from 13.88 to 53.00 mg dm−3 (**Figure 10**). The concentration distribution was characterized by relatively low dispersion. The highest concentrations were found in early spring during snow cover melting. In winter, snow from roads was discharged into the neighbourhood of the reservoir and in the valley of the Mała Panew river. Generally, snow from the roads contains increased amounts of chlorides used in winter road maintenance.

**Figure 10.** Changes in the average monthly chloride concentrations in the waters of the Turawa reservoir in the hydro-

The sulphates occur in natural waters in a wide range of concentrations. They are present at especially high concentrations, even up to 6000 mg dm−3, in mine waters. The Turawa reservoir is surrounded by coniferous forests which assimilate larger amounts of SO2 than deciduous forests. Sulphur in needle trees is in the form of sulphate ions, which can be leached out from fallen needles. However, anthropogenic factors had the most critical influence on the content of sulphates in the reservoir water. In the period studied, the average monthly concentration

Chlorides with water from snow melting could reach the reservoir.

The presence of sodium and potassium in natural waters is related to weathering of igneous rock and their leaching from sedimentary rock [8, 9]. Sodium salts are present in nearly all natural waters at the concentrations from several to 30 mg dm−3. Similar to chlorides, sodium ions can come from rock salt and also from sea aerosols. There are also several anthropogenic sources of sodium, mainly wastewater from soda producing and processing industry, and from dye industry.

Potassium is usually present in natural waters in small quantity, generally at the level of several mg dm−3. Strongly polluted industrial effluents and runoff water from fertilized arable land contain much higher concentration of potassium. Also in the leachate from municipal solid waste sites, potassium can be found at considerable concentrations.

In the Turawa reservoir, the average concentrations of Na+ and K+ ions were 12.4 and 4.5 mg dm−3, respectively. In the period studied, the monthly average concentrations of sodium and potassium were in the range of 7.3–17.0 and 3.5–6.6 mg dm−3 (**Figures 12** and **13**), respectively. Fluctuations of Na+ concentrations can be related to water level in the reservoir—the highest were in autumn-winter season when the water level was the lowest while the lowest were measured in spring during maximum filling of the reservoir. Seasonal changes of potassium concentration are not so distinct.

**Figure 12.** Changes in the average monthly sodium concentration in the waters of the Turawa reservoir in the hydrological years 2004–2006.

**Figure 13.** Changes in the average monthly potassium concentration in the waters of the Turawa reservoir in the hydrological years 2004–2006.

### **8. Concentration changes of organic substances**

### **8.1. Classes of organic compounds**

Surface waters can contain a wide spectrum of organic compounds belonging to different classes. The most important are carbohydrates, proteins, amino acids, esters, fats, organic acids, surfactants, soaps, ketones, alcohols, hydrocarbons, phenols, and also humic and fulvic substances. Most organic substances are of natural origin. Many are produced by animals and vegetation. They are also formed in the process of decay of dead remains of animal and vegetation. However, presently many organics found in surface waters come from anthropogenic sources. Except from humic substances, natural origin substances undergo biodegradation to simple inorganic compounds. Their presence is responsible for the deterioration of water smell and taste and can be harmful for living organisms. The presence of many anthropogenic compounds in surface water can disturb biological balance and make self-purification difficult [10].

Different human activities can really be a source of a large group of organic water pollutants. Chlorobenzenes are widely used in industry, in organic synthesis, and also as fungicides and insecticides. Some chlorophenols have fungicide and herbicide properties and some are used in producing other chemicals. Dioxins (polychlorodibenzodioxins and polychlorodibenzofurans), which are dangerous chemicals, are not produced on purpose, but they are contaminants of some chemical products. They are also formed in combustion of organic matter. Ethylenediaminetetraacetic acid is applied in steam generators to avoid precipitation of metals, in nuclear industry for surface treatment (decontamination), and so on. Glycols are used as hydraulic fluids and antifreeze agents. Polycyclic aromatic hydrocarbons are formed during forest fires, coal burning, and so on. Benzene, toluene, ethylbenzene and xylenes (BTEX) and aliphatic-chlorinated hydrocarbons are utilized as solvents. Volatile thiols can be present in the wastewater of petroleum industry. Anthropogenic phthalates are as common as natural chloride and sodium ions and presently can be found nearly everywhere; they are found in paints, inks, lacquers and solid organic polymers. Styrene can be found in plastics, synthetic rubber, copolymers; vinyl chloride is a residual monomer in polyvinyl chloride (PVC). Volatile organochlorinated compounds (VOX), mainly trihalomethanes (water chlorination), ethylene and ethane derivatives (solvents) can easily enter the environment. Some VOXs are produced by algae biomass in the process of chlorination. Pesticides include organochlorinated compounds (DDT, lindane, deldrin, etc.), organo-phosphorous compounds (parathion, malathion, etc.), sulphonates, carbamates and chlorophenoxy acetic acids. Phenols are formed in decomposition of vegetable products, can be present in industrial cellulose-containing wastewater, and were used as wood preservatives (pentachlorophenol). Sources of polychlorinated biphenyls (PCBs), pollutants widespread in the environment, are industrial wastes and leakage from transformers. PCBs undergo bioaccumulation easily. Being produced and applied or used in the production of other chemicals, organic compounds can enter the environment, including the surface water whereby they can be harmful in many ways.
