Determination of soluble salts in soil samples from Cyprus

1. Determination of soluble salts in soil samples from Cyprus Dr Irene Christoforou

2. Outline • Introduction • Sampling • Ion Chromatography • Ion Chromatography Method Development • Estimates of Reproducibility, Limits of Detection (LOD) and Limits of Quantification (LOQ) • Distributions of Fluorides • Distributions of Chlorides • Distributions of Nitrates • Distributions of Sulfates • Conclusions

3. Introduction • Soil comprises the loose top layer of our planet's crust and contains a mixture of rock particles, organic matter, bacteria, air and water. Minerals, nutrients Ions in solution Heat, cold, wind, rain, hail, ice Oxides of iron & alumina Spontaneous weathering Frost Silica Mechanical weathering Clays Parent material Fine parent material Carbonates Chemical weathering Acids, moisture

4. Introduction • Plants and crops are dependent on soil for the supply of water, nutrients and as a medium for growing. This dependence makes soil one of the most fundamental components for supporting life on the planet. • The term soluble salts refers to the inorganic soil constituents (ions) that are loosely bound to the matrix of soil and therefore can be dissolved in the water with relative ease. • The levels of soluble salts in the soil are important since high concentrations are considered an environmental stress and constitute a limiting factor for agriculture. • Furthermore some of the most important soil threats, such as salinisation and desertification are closely linked with increased concentrations of soluble salts. • Therefore, the determination of soluble salts in soils is crucial for the estimation of soil condition in relation to several soil threats and soil contamination.

5. Introduction • This study as a part of the compilation of the Geochemical Atlas of Cyprus project, aims to provide a detailed geochemical “snap shot” of the distribution and abundance of soluble salts in Cyprus soil. • For the purpose of this project an in-house method was developed for the extraction of soluble salts, following an optimized procedure. • The dissolved anions (F-, Cl-, NO3-, SO42-) were determined by liquid chromatography.

6. mafic units ultramafic unit Introduction Circum-Troodos Sedimentary Sequence (calcarenites, siltstones, carbonates) Keryneia Terrane (allochthonous massive and recrystallised limestones, dolomites and marbles) Mamonia Terrane (igneous, sedimentary, metamorphic rocks) Quaternary Troodos Ophiolite Complex & Arakapas Transform Sequence pillow lavas

7. Sampling Method • 5502 Top Soil Samples. • Sampling density - one site per 1 km2. • Troodos - reduced to one site per 2.2 km2. Areas not under the effective control of the Government of the Republic of Cyprus

8. Sampling Method • Sample locations - determined by GPS. • The surface was cleared of recent organic debris. • Top soil samples (0–25 cm depth). • All samples were sieved to <2 mm. • Samples delivered and archived at the GSD.

9. Ion Chromatography Eluent Data Processing Pump Conductivity Detector Guard Column Separator Column Suppressor Trace

10. Method Development

11. Method Development • Sample Preparation: • sieving < 2 mm mesh size • milling • Experimental • 5g sample / 200ml DW • 120 minutes shaking • filtration (ashless filter paper) • conductivity measurement • filtration (0.45 μm membrane filter) • liquid chromatography • Samples of conductivity greater than 600μS/cm or with anion concentrations exceeding the calibration range were diluted. • Control: • CYP-A , a calcareous sediment collected from an outcrop of Pakhna.

12. Method Development

13. Distribution of Fluorides • Fluorine is the most abundant halogen in the earth’s crust. • It is the most electronegative element and binds metals forming complexes, which are adsorbed readily to the soil and plants. • Fluorine is phytotoxic, causing damage in vegetation, wildlife and humans. • Fluorine as an element in soil has a world average value of 200-300 mg/kg. • The main natural source of inorganic fluorides in soil is the parent rock. During weathering, some fluoride minerals are rapidly broken down. • Fertilizer application is the main nongeogenic source of fluoride ions and fluorapatite is an important calcium- and fluoride-containing mineral used as a source of phosphates in the fertilizer industry. • Phosphate fertilizers are manufactured from rock phosphates, which generally contain around 3.5% of fluorine. • Fluoride applied through fertilizer tends to have high residence time within the soil matrix particularly in soils of high clay content, high organic carbon content, high amorphous aluminium species or low pH.

14. F- fluoride Ion chromatography 34 E 33 E Top soil (0 – 25 cm) Keryneia Areas not under the effective control of the Government of the Republic of Cyprus Lefkosia 500 Ammochostos Polis 25 22 F- (mg/kg) 35 N 20 19 Ayia Napa 18 16 14 12 Pafos 11 8 Lemesos Distribution of Fluorides LODreproducibility: 10 mg/kg average value: 18.7 mg/kg highest value: 3536 mg/kg

15. Distribution of Chlorides • The mantle, the crust and the oceans are the three main reservoirs of earth chlorine with only the oceanic chlorine being readily mobile. • Since parent materials in general contain only minor amounts of chloride, little of this nutrient arises from weathering. • Most of the chloride presents in soils arrives from rainfall, marine aerosols, volcanic emissions, irrigation waters, and fertilizers. • Chloride accumulates primarily in soil under arid conditions where leaching is minimal and where chloride moves upward in the soil profile in response to evapotranspiration . • Near the ocean, soils have high levels of chloride. • High chloride ion concentrations in soil, above geogenic concentrations, are often considered as a salinisation problem world wide and occur in warm and dry locations where soluble salts precipitate from water and accumulate in the soil.

16. Cl- chloride Ion chromatography 34 E 33 E Top soil (0 – 25 cm) Keryneia Areas not under the effective control of the Government of the Republic of Cyprus Lefkosia 2,000 Ammochostos 450 Polis 350 270 35 N 230 200 Ayia Napa 180 160 Cl- (mg/kg) 140 Pafos 120 80 Lemesos Distribution of Chlorides LODreproducibility: 149 mg/kg average value: 809.3 mg/kg highest value: 664778 mg/kg

17. The Nitrogen Cycle http://www.physicalgeography.net

18. Distribution of Nitrates • Nitrate ions mainly originate from anthropogenic origins and constitute a very clear descriptor for characterising agricultural land use. • The main source of nitrates is the application of synthetic fertilizers or manure to fields. • Potential anthropogenic source of nitrates is the leakage from domestic septic fields, municipal sewage systems and livestock facilities. • Excess nitrates in soil increases the risk of contamination of ground or surface waters causing eutrophication (increasing algae growth, degrading habitat for aquatic organisms) and adverse effects on human health. • Nitrate vulnerable zones (NVZ) have been designated by the Cyprus government through studies (Geological Survey Department, 2000) in an effort to comply with the Nitrate Directive (91/676/EEC). • The Directive has the objectives of reducing water pollution caused or induced by nitrates from agricultural sources and preventing further pollution.

19. 220 150 100 80 70 55 40 32 NO3- (mg/kg) 26 22 15 Distribution of Nitrates NO3- nitrate Ion chromatography 34 E 33 E Keryneia P ICP-MS Top soil (0 – 25 cm) Keryneia LODreproducibility: 12 g/kg average value: 68.4 mg/kg highest value: 3001 mg/kg Areas not under the effective control of the Government of the Republic of Cyprus Lefkosia Lefkosia Ammochostos Ammochostos Polis Polis 35 N Ayia Napa Ayia Napa Larnaca Pafos P (%) Lemesos Pafos Lemesos 0.160 0.100 0.092 0.085 0.062 0.055 0.042 0.035 0.025 0.020 0.010

20. Distribution of Sulfates • Sulfate ions are made available from dissolution of sulfate salts from oxidation of sulfur-bearing minerals in soils all around the world. • Among the sulfur-bearing minerals identified in sedimentary rocks, iron sulfide polymorphs, pyrite and marcasite, are the more common forms, of which pyrite is the most common. Oxidation of these sulfide groups releases sulfate phases into soils. • The soils that contain iron sulfide minerals or their oxidation products are known as Acid Sulfate Soils (ASS). • If the ASS are drained and exposed to air, the sulfides react with oxygen to form sulfuric acid which can create a variety of adverse impacts: killing vegetation and aquatic organisms, acidifying groundwater and water bodies, degrading concrete and steel structures to the point of failure.

21. 750 300 180 140 120 100 80 65 SO42- (mg/kg) 55 45 30 Distribution of Sulfates SO42- sulfate Ion chromatography 34 E 33 E Top soil (0 – 25 cm) Keryneia S XRF LODreproducibility: 49 mg/kg average value: 160.3 mg/kg highest value: 231701 mg/kg Keryneia Areas not under the effective control of the Government of the Republic of Cyprus Lefkosia Lefkosia Ammochostos Polis Ammochostos Polis 35 N Ayia Napa Ayia Napa Larnaca Pafos Lemesos S (mg/kg) Pafos 100,000 Lemesos 6000 1500 10,000 1200 S XRF (mg/kg) 1000 900 1,000 800 700 500 100 400 SO42- ion chrom (mg/kg) 300 200 10 10 100 1,000 10,000 100,000

22. F- fluoride NO3- nitrate Cl- chloride SO42- sulfate 34 E 34 E 34 E 34 E 33 E Top soil (0 – 25 cm) 33 E 33 E 33 E Keryneia Top soil (0 – 25 cm) Top soil (0 – 25 cm) Top soil (0 – 25 cm) Keryneia Keryneia Keryneia Lefkosia Lefkosia Lefkosia Lefkosia Ammochostos Ammochostos Ammochostos Ammochostos Polis Polis Polis Polis 35 N 35 N 35 N 35 N Ayia Napa Ayia Napa Ayia Napa Ayia Napa Pafos Pafos Pafos Pafos Lemesos Lemesos Lemesos Lemesos Distribution of Soluble Salts

23. Conclusions • The soluble salt distribution maps provide the baseline values for every geological formation of the island of Cyprus and give sufficient information of soil contamination sides. • The two salt lakes of the island are considered to be the main non-anthropogenic contamination sources resulting to enhance values of all the measured soluble salts and particularly those of the chlorides and sulfates. • The soluble salt distribution maps confirms also the anthropogenic soil contamination with nitrates and sulfates due to fertilizers application and mining activity respectively. • This study provides a basis for a number of future projects dealing with environmental monitoring and management. • The observed soil contamination caused by mining activity gives also the opportunity to run several mine rehabilitation projects in Cyprus.