Studi Persebaran Air Lindi Di Sekitar Tempat Pembuangan Akhir Wukirsari, Wonosari, Kabupaten Gunung Kidul Dengan Aplikasi Isotop Alam dan Kimia Air

DANIEL SURYA H, Prof. Dr. Ir. Agus Budhie Wijatna, M.Si. IPM.; Bungkus Pratikno, S.T., M.T.

2021 | Skripsi | S1 TEKNIK NUKLIR

Tempat Pembuangan Akhir (TPA) Wukirsari terletak di Wukirsari, Kecamatan Wonosari, Kabupaten Gunung Kidul (07 derajat 59'18.8"S, 110 derajat 37'00.2"E). Dengan pembuangan akhir sampah open-landfill dan volume sampah yang besar, air lindi cenderung dihasilkan akibat interaksi air hujan dengan tumpukan sampah. Rembesan air lindi berpotensi menembus permukaan tanah dan mencemari airtanah di sekitar TPA. Tujuan utama dari penelitian ini adalah menentukan pola sebaran pencemaran lindi di sekitar TPA Wukirsari dengan memanfaatkan isotop alam untuk memperoleh kesamaan genesis dan interkoneksi airtanah. Pada penelitian ini, komposisi isotop deuterium (2H atau D) dan oksigen-18 (18O) sampel airtanah sumur sekitar TPA dan sampel lindi dari kolam lindi diuji dengan mesin LGR DLT-100 untuk mendapatkan kesamaan genesis airtanah. Untuk mengetahui kualitas airtanah dan tipe kimia air, dengan metode diagram piper, dilakukan analisis kandungan: ion kation-anion berupa Natrium (Na+), Kalsium (Ca2+), Kalium (K+), Magnesium (Mg2+), Sulfat (SO4-2), Klorida (Cl-), aciditas/acidity (CO2-), dan Bikarbonat/alkalinitas (HCO3-); serta kandungan parameter fisik, Total Dissolved Solid (TDS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), besi (Fe), sianida (CN), dan timbal (Pb). Hasil analisis isotop alam menunjukan kesamaan genesis pada 6 lokasi sampel dengan rentang rasio isotop delta18O dan deltaD sebesar -6,878 permil s.d. −6,477 permil dan −47,735 permil s.d. −41,510 permil; dan pada 2 lokasi sampel dengan rentang masing- masing isotop sebesar −7,231 permil s.d. −7,015 permil and −51,064 permil s.d. −50,464 permil. Kesamaan genesis air pada lokasi sampel UTPA03 dan KDK01 menjelaskan bahwa adanya interkoneksi aliran airtanah antar lokasi sampel. Rasio isotop alam juga menunjukan tidak ada kesamaan genesis sampel air lindi dengan sampel airtanah. Dengan analisis pola pergerakan airtanah, maka diketahui bahwa air bergerak dari lokasi sampel UTPA03 ke selatan menuju KDK01 tanpa melalui daerah kolam lindi TPA Wukirsari. Pemodelan diagram piper menunjukan seluruh sampel airtanah dominan mengandung ion Ca2+, Mg2+, dan HCO3- dengan sifat kesadahan sementara. Seluruh sampel airtanah memiliki kualitas air yang baik, kecuali pada UTPA01 dan UTPA03 yang memiliki kadar BOD dan COD melewati ambang batas ketentuan bakumutu air yang telah ditetapkan pemerintah Indonesia.

Wukirsari Landfill is located in Wukirsari, Wonosari District, Gunung Kidul Regency (07 degree 59'18.8"S, 110 degree 37'00.2"E). With the waste final disposal of open- landfill and large volume of waste, leachate tends to be generated due to the interaction of rainwater with piles of garbage. Leachate seepage has the potential to penetrate the soil surface and contaminate groundwater around the landfill. The main objective of this research is to determine the distribution pattern of leachate pollution around the Wukirsari landfill by utilizing natural isotopes to obtain common groundwater genesis and interconnection. In this study, the composition of deuterium (2H or D) and oxygen-18 (18O) isotope in groundwater samples taken from wells around the landfill and leachate samples taken from leachate ponds were tested with the LGR DLT-100 machine to determine the sample's similiarity of groundwater genesis. To see the quality of groundwater and the water chemical type, by using the piper diagram method, an analysis of water content was carried out: the cation-anion ions are Sodium (Na+), Calcium (Ca2+), Potassium (K+), Magnesium (Mg2+), Sulfate (SO4-2), Chloride (Cl-), acidity (CO2-), and Bicarbonate/alkalinity (HCO3-); As well as the content of physical parameters, Total Dissolved Solid (TDS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), iron (Fe), cyanide (CN), and lead (Pb). The results of natural isotope analysis with delta18O and deltaD isotope ratios at 6 sample locations were -6,878 per mill to -6,477 per mill and -47,735 per mill to -41,510 per mill;and at 2 sample locations with ranges of −7,231 per mill to −7,015 per mill and −51,064 per mill to −50,464 per mill. The similarity of water genesis at sample locations UTPA03 and KDK01 explains that there is an interconnection of groundwater flow between sample locations. Natural isotope ratios also show that there is no similarity between the water genesis of leachate samples with groundwater samples. With the analysis of groundwater movement patterns, it is known that water moves from sample location UTPA03 to the south towards KDK01 without going through the leachate pond area of Wukirsari landfill. Piper diagram modeling shows that all of the dominant groundwater samples contain Ca2+, Mg2+, and HCO3- ions with temporary hardness properties. All groundwater samples had good water quality, except for UTPA01 and UTPA03 which had levels of BOD and COD exceeding the threshold for water quality standards that had been set by the Indonesian government.

Kata Kunci : TPA Wukirsari, pencemaran air lindi, hidrokimia, diagram piper, deuterium, oksigen-18