Geochemical Characteristics and Evaluation of the Groundwater and Surface Water in Limestone Mining Area around Gunungkidul Regency, Indonesia
Ten groundwater and six surface water samples were collected near the limestone mining region in Semin, Gunungkidul Regency, Daerah Istimewa Yogyakarta Province, Indonesia. This study is to investigate water characteristics using the geochemical method and to evaluate the groundwater and surface water for drinking and irrigation purposes in the study area. The samples were collected in 1000 ml polyethylene bottles. Prior to filling with sampling water, these bottles were rinsed to limit the chance of contamination. The hydrochemical characteristics of groundwater and surface water were determined using a Piper diagram. Groundwater samples were evaluated based on the Indonesia Minister of Health Regulation No: 492/ Menkes/Per/IV/2010 about the Requirements of Drinking Water Quality, while for irrigation water standards, surface water samples were evaluated based on the Government Regulation of the Republik Indonesia Number 82-year 2001 about Water Quality Management and Water Quality Control. All water samples are classified as CaHCO3 hydrochemical facies, except SMN-07 as CaCl hydrochemical facies. The element Ca is assumed to arise from the limestone dissolution of the Wonosari-Punung Formation in the CaHCO3 hydrochemical facies, whereas the HCO3 element is thought to derive from the dissolution of calcite or aragonite, which is usually abundant in limestone. Meanwhile, the element Cl in one CaCl hydrochemical facies sample could come from a variety of sources, including weathering of soil and rocks, industrial and home waste discharge, seawater intrusion, wastewater discharge, rainfall, and irrigation return flow. The surface water quality in the study area is suitable for irrigation. The quality of groundwater in the study area, although most of them are acceptable drinking water quality standards, there are several locations that do not accept the standards for drinking water quality, especially pH and Total Dissolved Solids.