Judul: Kondisi Histopatologi Ikan Mas Budidaya pada Lingkungan yang Tercemar Merkuri dan Selenium di Kawasan Pongkor Bogor dan Strategi Pengelolaannya
Abstrak: Mercury emissions from upstream gold mining and processing areas were found in high levels in waters, sediments, agricultural products, and fishes in Pongkor area led to conduct a study on reared carp fishes in same area from histopathological view. Selenium effect as antagonist of mercury, has never been studied before in this area. The study presents the total Hg and Se amount in water, sediments, and fish organs (gill, liver, kidney, intestine, spleen, and muscle), histopathology finding, and enviromental parameters that could influence the fish condition. Mercury and selenium were analyzed using acid digestion followed by determination of total mercury by atomic absorption spectrophotometry. Routine histopathological procedure was use after paraffin embedding and hematoxylin-eosin (HE) staining. The mercury concentrations in waters and organs was undetected, but there hundreds fold above the maximum limited permitted by Canadian Environment Quality Guidelines were detected in sediments. Tens fold selenium concentrations above the threshold level proposed by Lemly (2002) were also observed in sediments. In tissue, Se concentrations also reached tens fold above the threshold proposed by DeForrest et al. (1999). However, these higher concentration of fishes tissues could be worthwhile to metabolisms of fishes and people as antagonistic role of Se to Hg and either heavy metals found in this area. The histopathological changes that found within were degenerations and, necrosis, blood circulation alterations, and some parasites infections. This conditions could influenced by some environmental factors such as sediment type, hardness and alkalinity, water resources, leaching and flushing, and interaction with the other metals. Beside the good aquaculture practices, the strategy of management that could implemented to diminishing pollution of Hg and Se are : modification of construction of ponds; tandonitation; and biological, physical and chemical remediations.
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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: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix