Judul: Rekam Jejak Polutan pada Kerangka Kapur Karang Porites lutea di Pulau Tunda
Abstrak: Porites lutea is one of hard coral species which has sensitive respond to physical and chemical change of sea water. The line growth of Scleractinia’s skeleton has an ability to accumulate heavy metals continously as long as their life period. Therefore, it could be use as an enviromental changes indicator on long or short term period. This study aims is to assess trace pollutant record such as Pb, Sr, Cr and Zn which is accumulated in P. Lutea at windward and leeward Tunda Island. The sampling collection was conducted in coral core and analyzed by the outer circle of coral to determine the ages. Neutron Activation Analysis (NAA) was used to analyzes the heavy metals (Cr, Sr, Fe and Zn), while Atomic Absorption Spectrometer (AAS) was used analyze Pb. This research revealed metal concentration recorded in coral P. lutea skeleton in the windward location was started from 1940 to 2014 and in the leeward location started from 1969 to 2014, at which the metal concentrations increased. Cr concentration increased from 4.36 mgkg-1 to 11.77 mgkg-1, Fe concentration increased from 4.88 mgkg-1 to 47.70 mgkg-1, Zn concentration increased from 3.28 mgkg-1 to 15.59 mgkg-1, Pb concentration increased from 5.17 mgkg-1 to 17.66 mgkg-1. However, no increased of Sr concentration was observed, and it varied between 70.1-103.5 mgkg-1. It suggested that corals P. lutea can be used to evaluated changes at the environmental change from the past to the present at Tunda Island, to determining the concentration of pollutants recorded in the coral skeleton. The heavy metals concentration was increasing variation from year to years. The heavy metals concentration trend to increase towards percent years. This indicates that the region has contaminated due to possible anthropogenic activities from land.
Keyword: heavy metals, trace record in coral, P. lutea, Tunda Island

Judul: Rekam Jejak Logam Dalam Skeleton Karang Porites lutea Di Pulau Tunda, Banten dan Gugusan Pulau Pari, Kepulauan Seribu, Jakarta.
Abstrak: Porites lutea merupakan salah satu jenis karang masif yang bisa dijadikan bioindikator perubahan lingkungan laut. Selama masa hidup karang, karang melakukan kalsifikasi menghasilkan kalsium karbonat dan membentuk lapisan kerangka pertumbuhan yang dapat mencerminkan pertumbuhan dan umur karang. Bahan pencemar logam berat dari perairan teradsorpsi dan tersimpan pada lapisan pertumbuhan kerangka karang, logam berat tersebut akan tetap tertanam selamanya dalam kerangka karang karena pertumbuhan baru akan menutupi permukaan karbonat yang lama. Oleh karena itu, lapisan pertumbuhan karang masif diakui bermanfaat dalam penelitian untuk menelusuri perubahan lingkungan perairan di sekitarnya yang berbasis deret waktu. Penelitian ini bertujuan untuk mengungkapkan rekam jejak perubahan logam selama 30 tahun di Pulau Tunda, Banten dan Gugusan Pulau Pari. Sampel karang diambil di dua lokasi yaitu Pulau Tunda dan Gugusan Pulau Pari. Pengambilan sampel dilakukan dengan cara pengintian (coring) menggunakan bor pneumatic dengan bantuan alat SCUBA. Sampel karang dipreparasi, disinari dengan radiografi sinar X generator Rigaku Radioflex RF-300 EGM2 130 keV dan dianalisis dengan Coral XDS untuk menentukan lapisan umur karang. Konsentrasi logam berat diukur dengan alat ICP – OES. Hasil penelitian menunjukkan hasil rekam jejak perubahan logam pada skeleton Porites lutea. Terdeteksi adanya 4 logam berat yaitu Cr, Mn, Zn dan Al. Kerangka karang Porites lutea di lokasi Utara Pulau Tunda mencakup 30 lingkar tahun dari tahun 1986 – 2015, sedangkan di Gugusan Pulau Pari mencakup 88 lingkar tahun dari tahun 1925 – 2012. Penelitian ini hanya memfokuskan pada perbandingan rentang tahun 1986 – 2015. Hasil perbandingan untuk konsentrasi deposit logam yang terukur di kedua wilayah yaitu konsentrasi Cr < Mn < Zn < Al yang terdeposit dalam skeleton karang Porites lutea dalam Pulau Tunda dan Pulau Pari. Kecenderungan konsentrasi logam berat mengalami kenaikan per-tahunnya. Konsentrasi logam berat di Gugusan Pulau Pari lebih tinggi dari pada di Pulau Tunda. Hal ini mencerminkan bahwa logam berat di perairan Gugusan Pulau Pari relatif lebih tinggi, diduga karena konsentrasi di lingkungan perairan lebih tinggi.
Keyword: ICP-OES,, Logam, Porites lutea, Pulau Pari, Pulau Tunda

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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