Judul: Konsentrasi Logam Berat Timbal (Pb) pada Air, Sedimen, dan Rumput Laut Sargassum polycystum di Perairan Pulau Pari, Kepulauan Seribu
Abstrak: The aim of this research was to analyze the lead (Pb) concentration in water, sediment, and Sargassum polycystum at Pari Island, Seribu Islands. Sample of water, sediment, and Sargassum polycystum were collected in August 2014 from Pari Island. The heavy metal concentrations were then analyzed by Atomic Absorption Spectrometry methods. The results showed that Pb concentrations in water, sediment, and Sargassum polycystum was 0,009 - 0,015 mg/l, 44,72 - 50,01 mg/kg and 16,89 - 17,59 mg/kg, respectively. Lead concentrations in water exceeded its normal concentration in natural waters. However, the concentration of Pb in sediment was still in the range of non-polluted waters. The indications of Pb in this waters showed an increasing trend and accumulatic in Sargassum polycystum.
Keyword: Bogor Agricultural University (IPB), Pari Island, Sargassum polycystum, Sediment, Water, Lead

Judul: Konsentrasi Logam Berat Timbal (Pb) dan Tembaga (Cu) pada Sedimen dan Air di Perairan Pelabuhan Klidang Lor, Batang, Jawa Tengah
Abstrak: Lead (Pb) and copper (Cu) are toxic and persistance pollutants. The information on these heavy metals water quality in the Port Klidang Lor is still limited, whereas the activities of fishing port have been growing fast. The objective of this study was to determine distribution the concentration of lead (Pb) and copper (Cu) in sediments and water in the Klidang Lor coast of, Batang, Central Java. Sediment and water samples were taken from 11 stations in April 2014. The analysis of heavy metals was performed using Atomic Absorption Spectrometry (AAS) with following APHA procedure (ed 22 , 2012, 3111 – B). Dissolved Pb and Cu concentrations varried in the water column between 0.003-0.006 mg/L and 0.007-0.008 mg/L lower than the these of threshold limit by ministry of environment. The concentration of Pb in sediment ranged between 12.73- 21.07 mg/kg and the concentration of Cu in sediment ranged from 7.73-27.21 mg/kg lower than the these of threshold limit by Dutch Quality Standard For Metals in Sediments. Source of the heavy metal concentration in these waters were possibly to be derrived from an oil spill of the vessel, the activity of shipyards, settlement activity in surrounding port. Variations of heavy metal concentration are also affected by the size of particles in the sediment and organic content.
Keyword: Bogor Agricultural University (IPB), Copper, lead, Sediment, Heavy metal, Klidang Lor-Batang

Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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