Judul: Heavy Metal Content of Pb and Cd of Rice-Field Frog (Fejervarya cancrivora) in Karawang Regency, West Java
Abstrak: Keberadaan industri yang membuang limbah di DAS Citarum menyebabkan tercemarnya air Sungai Citarum. Sebagian air limbah industri mengandung logam berat yang membahayakan kehidupan biota air sungai maupun kesehatan manusia. Penggunaan air Sungai Citarum untuk drainase air persawahan menyebabkan ekosistem pesawahan tercemar logam berat. Penelitian bertujuan untuk mengidentifikasi kandungan logam berat pada air, sedimen, dan daging katak sawah (F. cancrivora) di Kabupaten Karawang. Pengambilan sampel dilakukan di Kecamatan Karawang Barat dan Kecamatan Klari dengan 3 plot pada masing masing lokasi. Analisis logam berat dilakukan di Laboratorium Terpadu IPB menggunakan metode AAS. Hasil penelitian menunjukkan logam Pb pada air <0,02 dan Cd <0,005 ppm; sedimen Pb 2,43-4,11 ppm dan Cd <0,1 ppm; sedangkan daging katak Pb <0,3 ppm dan Cd <0,1 ppm. Rendahnya kandungan logam berat dalam air, sedimen, dan daging katak diduga karena rendahnya kandungan logam berat dari limbah industri serta proses penyerapan logam berat oleh tanaman air dan mengendap bersama sedimen di lahan sawah. Rendahnya Pb dan Cd dalam air menyebabkan rendahnya faktor biokonsentrasi pada katak sawah (F. cancrivora) (<100).
Keyword: bioconcentration, frog, heavy metals, ricefield

Judul: Bioconcentration of Metal Mercury (Hg) in the Crab Eating Frog (Fejervarya cancrivora) in the Cikotok Gold Mining Area, Lebak Regency
Abstrak: Usaha pertambangan emas selain menghasilkan nilai ekonomi, tetapi juga memberikan dampak negatif pencemaran merkuri bagi lingkungan sekitarnya. Penelitian konsentrasi merkuri pada lingkungan pertambangan emas dilakukan di lingkungan sekitar Sungai Pasirgombong yang aliran sungainya melewati kawasan pertambangan emas Cikotok. Pertambangan dan pengolahan emas di kawasan ini menggunakan metode amalgamasi menggunakan merkuri, yang memiliki potensi pencemaran limbah merkuri. Penelitian ini bertujuan menganalisis konsentrasi merkuri pada katak sawah, sedimen sungai serta lingkungan air sebagai habitatnya. Lokasi sampling terbagi atas tiga stasiun, yaitu hulu sungai, lokasi kegiatan, dan hilir sungai. Analisis kandungan merkuri dilakukan di Laboratorium Produktivitas dan Lingkungan Perairan IPB University. Hasil analisis menunjukkan kadar merkuri di air sebesar 0,0007-0,0011 mg/l; pada sedimen sebesar 0,252-24,069 mg/kg dan pada paha katak sebesar 0,095-0,118 mg/kg. Kadar merkuri di air masih dibawah baku mutu air, sedangkan kadar merkuri di sedimen dan katak sudah melebihi baku mutu. Faktor biokonsentrasi pada katak terhadap air sebesar 107-208 kali atau tergolong “akumulasi sedang”., The gold mining business not only produces economic value but also has a negative impact on mercury pollution for the surrounding environment. Research on mercury concentrations in the gold mining environment was carried out in the vicinity of the Pasirgombong River which flows through the Cikotok gold mining area. Gold mining and processing in this area uses the amalgamation method using mercury, which has the potential for mercury waste contamination. This study aims to analyze the concentration of mercury in the crab eating frog, river sediments and the water environment as their habitat. The sampling location is divided into three stations namely upstream, activity locations, and downstream. Mercury analysis is carried out in the Proling Laboratory IPB University. The results of analysis showed that mercury levels in the water were 0,0007-0,0011 mg/l. Mercury levels in sediments are 0,252-24,069 mg/kg and frogs are 0,095-0,118 mg/kg. The mercury level in the water is still below the quality standard, while the mercury level in the sediment and frogs has exceeded the quality standard. The bioconcentration factor in frogs to water is 107-208 times and classified as "medium accumulation".
Keyword: air, merkuri, logam berat, pencemaran, heavy metal, mercury, pollution, water

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology