Judul: Pengaruh Akumulasi Kromium (Cr) Terhadap Perubahan Struktur Komunitas Dan Histologis Makrozoobentos Di Sungai Cimanuk Lama Indramayu
Abstrak: Sungai Cimanuk Lama memiliki aliran yang banyak dimanfaatkan oleh masyarakat sekitar seperti untuk ketersediaan air setempat, kegiatan pertanian, perikanan dan juga industri batik. Aktivitas tersebut berpotensi mencemari lingkungan perairan Sungai Cimanuk Lama dan salah satunya pencemaran logam berat kromium dari industri batik. Logam berat tersebut dapat terlarut dalam air, bersifat korosif, toksik dan terendap di dasar perairan serta terakumulasi dalam tubuh organisme air. Tujuan penelitian ini adalah mendeskripsikan pengaruh aktivitas manusia seperti industri batik yang dapat mencemari perairan sungai dan berdampak terhadap struktur komunitas dan histologis makrozoobentos di Sungai Cimanuk Lama, Kabupaten Indramayu. Pengambilan contoh dan analisis data dilakukan dari bulan April sampai dengan September 2015 di Sungai Cimanuk Lama Kabupaten Indramayu. Sampel penelitian diperoleh dari 3 lokasi berbeda. Stasiun lokasi penelitian terdiri stasiun 1 (daerah sebelum industri batik), 2 (daerah sekitar industri batik) dan 3 (daerah setelah industri batik). Metode penelitian survey dengan analisis data meliputi kandungan kromium (air, sedimen, Bellamya sp. dan Pilsbryoconcha exilis), struktur komunitas makrozoobentos (kepadatan, keanekaragaman, dominansi, keseragaman dan Family Biotics Index) dan gambaran kondisi histologis moluska (kelenjar pencernaan, saluran pencernaan dan otot gerak). Pengambilan sampel sedimen dan makrozoobentos menggunakan van veen grab, sedangkan pengambilan sampel air menggunakan kemmerer water sampler dekat dengan dasar perairan. Hasil pengamatan makrozoobentos diperoleh 15 jenis dengan total 9877 individu yang ditemukan dengan kelas gastropoda dan oligochaeta mendominasi di semua stasiun. Hasil penelitian menunjukkan bahwa kandungan logam berat kromium di dalam air berkisar 0.01 sampai 0.016 mg L-1, sedimen 9.4 sampai 53.65 mg kg-1, tubuh keong tutut (Bellamya sp.) 2.13 mg kg-1 sampai 17.41 mg kg-1, dan kerang kijing lokal (Pilsbryoconcha exilis) 2.16 mg kg-1 sampai 37.81 mg kg-1. Secara keseluruhan indeks komunitas makrozoobentos yang teramati menunjukkan nilai yang lebih baik di stasiun 1 dibandingkan dengan dua stasiun lainnya. Analisis histologi menunjukkan, semakin hilir letak stasiun penelitian maka semakin tinggi derajat kerusakan pada Bellamya sp. dan P. exilis. Aktivitas manusia di sekitar Sungai Cimanuk Lama ditambah adanya kegiatan industri batik terbukti berdampak pada biota akuatik dan memperburuk kondisi lingkungan perairan.
Keyword: Kromium, Komunitas makrozoobentos, Histologi moluska, Industri batik

Judul: Kandungan Logam Berat Kromium (Cr) dalam Air, Sedimen, dan Ikan Nila (Oreochromis niloticus) serta Karakteristik Biometrik dan Kondisi Histologisnya di Sungai Cimanuk Lama, Kabupaten Indramayu
Abstrak: The heavy metal chromium which contained in batik wastewater will cause the water gets polluted if it is discharged directly to the Cimanuk Lama River, Indramayu District without any treatment. This is happened because the heavy metal chromium dissolved in the water, settled in sediment, and accumulated in fish body. The negative impact of chromium heavy metal to fish is lead to stress, disruption of physiological processes, affecting the health, and lead to death. There will also accumulate chromium heavy metal in the body so it is not feasible consumed by the humans because endangering the health. The fish that are found in the Cimanuk Lama River was Nile Tilapia. The Nile Tilapia (Oreochromis niloticus) will accumulate chromium heavy metal in the body and cause tissue damage and impaired growth. The objectives of the study were to review the content of the heavy metal chromium in water, sediment, nile tilapia fish (O. niloticus), and biometric characteristic and their histological condition in the Cimanuk Lama River, Indramayu District. This information can be used as a reference to consume Nile Tilapia and to manage the Cimanuk Lama River, Indramayu District by the community. This study was conducted from February to April 2014. Sampling for the water and the content of chromium heavy metal every month at three observation stations. Station 1 is the area of the river there is no industrial activity and residential areas, Station 2 is located around the batik industry area and residential areas, and station 3 is downstream of the basin after the batik industry activities, residential areas, and agricultural activities. Sampling of Nile Tilapia using gill net with mesh size of 1,5 inch. Nile Tilapia which is used in this study come from the catch and which are cultivated in floating cage by the fisherman. The result showed that content of chromium in the water was range from 0,85– 0,91 mg L-1, in sediment was 27,39–37,12 mg kg-1 and in body fish was 18,01–91,76 mg kg-1. There patterns isometric, allometric negative, and allometric positive. Condition factor (1,618–2,587), gonado somatic index (0,086–2,318 %), fecundity (568–1192 grains/ individual), egg diameter (0,358–0,467 μm), hepato somatic index (0,621–2,063 %) and relative weight gill (4,022–6,102 %). Gills and liver damage of nile tilapia fish classified as low to high level. Batik industry activity arround the Cimanuk Lama River, Indramayu District of contributed significantly to chromium heavy metal pollution.
Keyword: Cimanuk Lama River, histological condition, Nile Tilapia fish, chromium heavy metal, biometric characteristic

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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