Penilaian Spasial Potensi Risiko Ekologis Logam Berat di Lapisan Olah Tanah Sawah DAS Serayu Hilir, Jawa Tengah

Abstract

Abstrak. Logam berat di DAS perlu diteliti untuk mengetahui tingkat cemarannya pada tanah. Tujuan penelitian ini adalah untuk menilai tingkat kontaminasi logam berat di tanah sawah DAS Serayu Hilir. Penelitian dengan metode survey dilakukan dengan mengambil sampel tanah sawah pada kedalaman 0-20 cm. Distribusi lokasi sampel tanah dan risiko ekologis karena logam berat di lapisan atas tanah sawah DAS Serayu Hilir ditentukan secara grid. Sampel tanah dianalisis kandungan Pb, Cd, Co, Cr, Ni, Cu, Mn, Zn, As, dan Fe total dengan pelarut asam dan pengabuan basah. Analisis multivariat dan geostatistik dilakukan dengan menghitung indeks bahaya seperti geo-akumulasi, kontaminasi, beban polusi, dan risiko ekologis. Konsentrasi logam berat di lokasi penelitian adalah As < Cd< Zn< Cu< Cr< Co< Pb < Ni< Mn< Fe. Kontaminasi logam berat Pb, Cu, Ni, Cr, Fe, Co, Mn, As, dan Zn pada lapisan olah tanah sawah berasal dari kegiatan antropogenik, sedangkan kontaminasi As dan Cd disebabkan oleh sedimentasi geologis dan atmosfer. Tanah terkontaminasi tinggi (CF = 3-6) oleh Cd, dan terkontaminasi rendah (CF <1) oleh kontaminan Fe, Mn, Ni, Pb, Co, Cr, Cu, Zn, dan As. Potensi risiko ekologis termasuk kategori sedang pada logam kadmium, sedangkan logam lainnya tergolong rendah. Kontaminasi logam berat Cd dapat menimbulkan risiko ekologis dan keracunan manusia.

Abstract. Heavy metal concentration in the watershed needs to be examined to determine the level of heavy metal contamination in soil. The study aimed to assess the level of heavy metal contamination in rice field at the Serayu Hilir watershed. Soil survey was conducted to collect soil samples from topsoil layer (0-20 cm). Distribution of soil sample location and ecological risk due to heavy metals at the top soils of the Serayu Hilir watershed were determined with grid bases. Soil samples were analyzed for total Pb, Cd, Co, Cr, Ni, Cu, Mn, Zn, As, and Fe with acid solvents and wet ashing methods. Multivariate and geostatistical analyses were conducted by calculating various hazardous indices such as geo-accumulation, contamination, pollution load, and ecological risk. Concentration of metals at the research site were in the order: As < Cd< Zn< Cu< Cr< Co< Pb < Ni< Mn< Fe. Contaminations of Pb, Cu, Ni, Cr, Fe, Co, Mn, As, and Zn were mainly derived from anthropogenic origins whereas, As, and Cd contaminations were mainly caused by geological and atmospheric precipitations. The soil was was highly contaminated (CF = 3-6) by  Cd, and lowly contaminated (CF <1) by Fe, Mn, Ni, Pb, Co, Cr, Cu, Zn, and As. The potential ecological risk is moderate for cadmium, while for other heavy metals are classified as low. Cd heavy metal contamination can raise ecological risks and human poisoning.