Judul: Distribution and Bioaccumulation of Heavy Metals (Cu, Hg, Dan, Pb) in the Mangrove Ecosystem in Pohuwato Regency, Gorontalo Province
Abstrak: Ekosistem mangrove merupakan suatu ekosistem yang unik dimana area tumbuh dari tumbuhan ini berada di lingkungan yang ekstrim. Ekosistem ini dapat ditemukan pada daerah tropis dan subtropis pada wilayah intertidal yang mendominasi wilayah garis pantai dan muara sungai. Ekosistem Mangrove berperan dalam bidang fisik, kima dan biologi sehingga peran ini penting dalam siklus hidrobiologi dalam suatu ekosistem. Kegiatan pemanfaatan suatu lahan tanpa memperhatikan dampak yang ditimbulkan semakin meningkatkan kerusakan lingkungan. Kerusakan lingkungan akan semakin parah apabila masuknya bahan-bahan berbahaya dalam hal ini logam berat yang berasal dari aktivitas antropogenik. Tujuan dari penelitian ini adalah mengetahui konsentrasi logam berat (Cu, Hg dan Pb) dari hulu dan hilir, menganalisis tingkat pencemarannya dilihat dari Faktor Pengkayaan dan Indeks Geoakumulasi serta mangrove yang berperan dalam penyerapan logam berat dilihat pada bagian sedimen, akar dan daun, serta bagian dari tumbuhan mangrove yang dominan dalam penyerapan logam berat. Penelitian ini dilakasanakan pada bulan Februari-Maret 2018 di Kabupaten Pohuwato Provinsi Gorontalo. Sampel diambil pada 7 lokasi meliputi area tambang bagian atas, area tambang bagian bawah, muara, laut, ekosistem mangrove bagian timr, ekosistem mangrove bagian tengah dan ekosistem mangrove bagian barat. Terdapat dua jenis mangrove dalam penelitian ini yaitu Rhizophora mucronata dan Sonneratia alba. Penelitian ini menggunakan AAS (Atomic Absorption Spectrophotometer) dan microwave digestion untuk mengekstrak logam dari sampel air, sedimen, akar dan daun mangrove. Hasil analisis menunjukkan konsentrasi Cu dan Pb pada air mengalami peningkatan konsentrasi pada 7 lokasi yaitu < 0,0147 mg/L dan 0,031 – 0,120, sementara Hg yaitu < 0,0004 mg/L. Pada sedimen konsentrasi mengalami peningkatan dibandingkan dengan air, Cu 2,72 – 3,64 mg/Kg, Hg 0,0004 – 0,1243 mg/kg dan Pb pada berkisar 2,92 – 9,51 mg/Kg. Kualitas sedimen menunjukkan terjadi peningkatan pengkayaan logam berat pada level pengkayaan sedang. Sumber antropogenik berperan dalam peningkatan konsentrasi Hg dan Pb. Mangrove jenis R.mucronata dan S. alba memiliki kemampuan dalam penyerapan logam dalam jaringannya. Penyerapan logam berat pada jaringan atas S.alba > R.mucronata. Berdasarkan studi ini dapat diindikasikan bahwa ekosistem mangrove merupakan mitigasi alami dalam hal penyerapan logam berat yang berasal dari segala aktivitas di darat., The mangrove ecosystem is a unique ecosystem where the growing area of this plant is in an extreme environment. This ecosystem can be found in tropical and subtropical in intertidal areas that dominate the coastline and river estuaries. Mangrove ecosystems play a role in the physical, chemical and biological fields so that this role is important in the hydrobiological cycle in an ecosystem. The activity of utilizing a land without paying attention to its impact will further increase environmental damage. Environmental damage will get worse if the entry of hazardous materials, in this case heavy metals, comes from anthropogenic activities. The purpose of this study was to determine the concentration of heavy metals (Cu, Hg and Pb) from upstream and downstream, to analyze the level of pollution seen from the Enrichment Factor and Geoaccumulation Index and mangroves which play a role in the absorption of heavy metals seen in the sediment, roots and leaves, and parts from mangrove plants which are dominant in the absorption of heavy metals. The research was conducted in February-March
Keyword: Bioakumulasi, Logam Berat, Rhizophora mucronata, Sonneratia alba

Judul: Akumulasi Logam Berat Tembaga (Cu) dan Timbal (Pb) pada Pohon Mangrove (Rhizopora mucronata) di Perairan Karangsong, Indramayu.
Abstrak: Mangrove has many economical and ecological functions, one of its abilities is to absorb, transport and store substances including toxic materials. This research aim is to analyze the concentration of Cu and Pb in root, leave and substrat of mangrove Rhizopora mucronata and its bioaccumulation level. The concentration of Cu found in sediment exceed standar quality by RNO, which means the sediment has been contaminated by Cu. The content of Cu in the roots and leaves of mangrove is greater than Pb, so does the highest level of bioconcentration factor (BCF) was reached by BCF Pb in root at 1.3116 while BCF Cu in roots at 0,5609. This indicates that the potention of accumulation of roots is much higher than the leaves. The highest Translocation Factor (TF) was attained by Pb which is 0.4075 and the lowest is 0.3341 in Cu. Metal translocation from roots to leaves for essential metals (Cu) is lower than in non-essential metals (Pb), it shows that the mangrove use Cu for metabolic activity and growth. The ability of mangrove in accumulating this metals are still low in category according to Concentration Factor Index.
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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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