Evaluation of the Influence of the Heavy Metals Content on the Possibility to Use the Waters from selected Strzelin Quarry Lakes for Agricultural Irrigation

The article presents the evaluation of the influence of the heavy metals content in the water from selected Strzelin Quarry Lakes located in Central Europe) on the possibility to use the water for irrigation. The guidelines provided by FAO and in PN-84/C-04635 were the basis of the evaluation. The water pH ranged from 7.1–9.0, on average 7.8. The zinc content was in the range from 0.40–29.00 μg·dm-3, on the average 14.40 μg·dm-3, while the content of copper ranged from 0.00–50.10 μg·dm-3, on average 21.13 μg·dm-3. The cadmium content fell into the range from 0.00–5.50 μg·dm-3, on the average 0.83 μg·dm-3, and the lead content ranged from 0.00–18.10 μg·dm-3, on average 3.16 μg·dm-3. The chromium content ranged from 0.00–21.00 μg·dm-3, on average 4.26 μg·dm-3 and, finally, the content of nickel ranged from 0.00–39.80 μg·dm-3, on average 6.70 μg·dm-3. The values of the analysed heavy metals were similar to the concentrations noted in natural lakes and artificial water reservoirs. As far as the heavy metal content is concerned, the water from the selected Strzelin Quarry Lakes met the requirements that allow using it for the purposes of agricultural irrigation.

There are many ways to use the water retained in quarry lakes; for example, it can be used: for fish breeding, as a source of potable water, for agricultural and horticultural irrigation, source of industrial water, etc. The aim of the research was to evaluate the usability of the surface water from selected Strzelin Quarry Lakes for the agricultural irrigation, in terms of the heavy metal content. This article is a continuation of the publication of the usability of the water from selected Strzelin Quarry Lakes for agricultural irrigation, published by Jawecki and co-workers (2019a).
The quoted paper (Jawecki et al., 2019a) presented the evaluation of the possibility to use the water from selected Strzelin Quarry Lakes for agricultural irrigation, where the following indicators were analysed and assessed: electrical conductivity, Sodium Adsorption Ratio, Total Dissolved Solids, water pH, BOD 5 , and ion concentrations of: nitrates, sulphates, chlorides, sodium, manganese, and iron. The authors stated (Jawecki et al. 2019a) that in terms of the analysed indicators, the water from the Strzelin Quarry Lakes met (with some minor limitations) the requirements that enable its use for agricultural irrigation, in particular sprinkler irrigation.

MaterIals and Methodology
The Strzelin Quarry Lakes are located in Central Europe, in the south-eastern part of the Lower Silesian Voivodeship, County Strzelin ( Fig. 1). The characteristics of the spatial development and land use, geological structure, impact of Strzelin quarries on the environment and reclamation of Strzelin quarries were presented among others in the publications of Jawecki and co-workers ( Water sampling was conducted in 5 quarries (3 quarries were closed, 1 were quarries active, and 1 quarry was periodically active), the basic characteristics of which are presented in publication by Jawecki and co-workers (2019a). The samples of water were collected from 2 granite quarries (Q1-G, Q3-G) 1 tonalite, diorite and granite quarry (Q2-TDG), 1 quartzite schist quarry (Q4-QS), 1 marble quarry (Q5-M). Four of the quarries are non-outflow (Q1-G, Q2-TDG, Q3-G, Q4-QS), the water from one quarry (Q5-M) runs off by gravity to a drainage ditch, the part of water from two quarries (Q1-G, Q4-QS) is periodically pumped out and discharged outside the quarry (Jawecki et al. 2019a).
The methodology of sampling (depth from water surface, distance from the shore, hour of sample collection, measurement period) were presented in the articles of Jawecki and co-workers (2019a) and Jawecki & Mirski (2018). The methodology for calculating the water surface area and depth of the analysed Strzelin Quarry Lakes were presented in the article of Jawecki and co-workers (2019a).  (Ayers & Westcott, 1985).
the average values from the measurement period of concentration of heavy metals (Zn, Cu, Cd, Pb, Cr, Ni,) and water pH were used for evaluating possibility to use the water from the selected Strzelin Quarry Lakes for irrigation. The overall evaluation were made by adopting the worst average value of the analysed indicators. The methodology of calculation of average value of pH, standard deviation of average concentration of heavy metals, were presented in a paper by Jawecki and co-workers (2019a).

results and dIscussIon
The average pH of water in selected Strzelin Quarry Lakes fell into the range 7.45-8.06 (Table 1), with the most frequently noted pH value of 8.4, although the pH of water in the analysed quarries ranged from 7.1-9.0 (Table 1) (Mayne, 1994). The pH values obtained by Jawecki and Mirski (2018) in eutrophic granite quarries ranged from 7.2-9.3. In the granite quarry (Q3-G), the water pH value (9.0 and 8.6) exceeded the range observed in natural lakes (pH 6.5-8.5) and the range (pH 6.5-8.4) recommended by FAO for the water used in irrigation (Ayers & Westcott, 1985). The water pH value of 8.0, recommended by Polish Reference Standard PN-84/C-04635 for irrigation (Kaniszewski &Treder, 2018) was exceeded mainly in the summer, in 56% of the samples (Jawecki et al. 2019a). A wider evaluation of the influence of pH of the analysed quarries of the suitability of water for use in irrigation was presented in the quoted study by Jawecki (2019a).
The average zinc content in the analysed quarry lakes fell into the range 11.32-21.02 μg·dm -3 , (Fig. 2, Table 1). The highest content (29.00 μg·dm -3 ) was noted in the Q5-M marble quarry (Table 1), and the lowest one (0.40 μg·dm -3 ) in the Q3-G granite quarry (Table 1) The average copper content in the analysed quarry lakes fell into the range 18.16-24.04 μg·dm -3 , (Fig. 2, Table 1). The highest concentration (50.10 μg·dm -3 ) was noted in the Q5-M marble quarry (Table 1). However, in December 2016, no copper at all was found in the Q3-G and Q4-QS quarry lakes ( Table 2). The copper content found in the Strzelin Quarry Lakes was similar to the values noted in lakes (0.13-41.5 μg·dm -3 )  The average cadmium content in the analysed quarry lakes ranged from 0.5-1.48 μg·dm -3 , (Fig. 2, Table 1). The highest concentration (5.5 μg·dm -3 was noted in the Q3-G marble quarry (Table 1). In autumn and winter, no cadmium was detected in 64% of the water samples from the analysed Strzelin Quarry Lakes ( Table 2) , 2012)). As the cadmium content in the analysed water was below 0.1 mg·dm -3 it did not lead to any restrictions in using the water from the analysed quarry lakes for the irrigation purposes (PN-84/C-04635, Ayers & Westcott, 1985, Kaniszewski & Treder, 2018. The average lead content in the analysed quarry lakes fell into the range 2.52-3.62 μg·dm -3 , (Fig. 2, Table 1). The highest concentration (18.10 μg·dm -3 ) was noted in the Q1-G granite quarry (Table 1). No lead at all was detected in 80% of the samples of water from the Strzelin Quarry Lakes (Table 1) The average chromium content in the analysed quarry lakes fell into the range 2.06-6.24 μg·dm -3 (Fig. 2, Table 1). The highest concentration (21.0 μg·dm -3 ) was noted in the Q3-G granite quarry (Table 1). In the autumn of 2016 and spring of 2017, chromium was detected in quarry lakes, whereas in the other cases (60% of samples) no chromium was found at all ( Table 1) As the chromium content in the analysed water was below 0.1 mg·dm -3 it did not lead to any restrictions in using the water from the analysed quarry lakes for the irrigation purposes (PN-84/C-04635, Ayers & Westcott, 1985).

suMMary and conclusIons
The Strzelin Quarry Lakes presented in the article emerged in the closed quarries of granitoides, quartzite shale, and marble result from the flooding by rainwater and ground water. They are characterised by relatively small surface areas ranging from 0.89 ha to 3.60 ha, but also relatively large depths of 10-25 m (max. 40 m), so they may potentially store large amounts of water , Jawecki et al., 2019b and become a potential source of water to be used in agriculture (Jawecki 2019a), and for economic purposes.
The quarry lakes are supplied by rainwater, as well as the surface and sub-surface runoff from the direct catchment of the quarry lake. The concentration of heavy metals in the waters of the selected Strzelin Quarry Lakes is relatively low, similar to that in natural lakes. Simultaneously, the concentration of heavy metals in the water of the analysed Strzelin Quarry Lakes, is lower than in most pit lakes, for example in acidic AML and pit lakes that emerged after the excavation of metal ores.
According The content of heavy metals in the analysed Strzelin Quarry Lakes met the requirements on using water for irrigation provided in the international guidelines and Polish guidelines ( Table 2). Some restrictions on using the analysed water for irrigation were noted with respect to pH (in quarry Q1-G), but this issue has been discussed more widely in the referenced study by Jawecki and coworkers, (2019a). The conducted research allowed the authors to formulate the following conclusions: 1. The content of heavy metals (Zn, Cu, Cr, Cd, Pb, and Ni) in the waters of the analysed Strzelin Quarry Lakes met the requirements on using water for irrigation provided in the international and Polish guidelines. 2. The concentrations of heavy metals found in the waters of the analysed Strzelin Quarry Lakes were similar to those in natural lakes, decidedly lower than in most pit lakes, especially AML, and the pit lakes emerging after the excavation of metal ores. 3. As far as the concentration of zinc, copper, and chromium are concerned, the water in the analysed Strzelin Quarry Lakes met the requirements of surface water quality indicators for Class II of the chemical state of the waters, whereas the content of cadmium, lead, and nickel exceeded the threshold values of AA-EQS and MAC-EQS concentrations for natural water courses and lakes.