Judul: Environmental conditions related to community structure of macrozoobenthos in Belumai River District of Deli Serdang, North Sumatera Province.
Abstrak: Belumai River is one of the rivers in Deli Serdang Regency, North Sumatra Province. Activity along Belumai River basin includes the activity of industrial, domestic and agricultural activities. The Belumai River used by some people for bathing, washing, toilet (MCK). People who use the river water susceptible of contracting diseases including skin irritation and eye irritation. Belumai River environment has a very important component of people lives around the river. Increasing of development activities such as input from industrial waste, urban sewage and runoff of agricultural water carried by the currents have an impact on water quality degradation Belumai River. The high activities have affected the composition and abundance of species makrozobentos in the Belumai River. Only those species that are tolerant of the environment can still survive. The purpose of this research is to analyze the relationship environmental conditions with community structure of macrozoobenthos. This research was conducted in Belumai River Deli Serdang Regency, North Sumatra Province, on 4 stations for 3 months, with a time interval of 1 month. Determination of the station, based on consideration of the different input load from any location, thus defined three sub-districts into the sampling site, which is 1 station in the district of STM Hilir, station 2 and station 3 in the District of Tanjung Morawa, and 4 station in the District of Batang Quiz. Samples collected consisted of physical parameters, namely temperature, currents, depth, turbidity, and type substrate. Chemical parameters namely pH, DO, COD and TOM. Macrozoobenthos was collected as biological parameter. Macrozoobenthos were found during research in Belumai River consists of 3 classes (gastropods, insects and Oligochaeta). Station 1 genus number obtained during the observation that there are 5 genera : Branchiura sp., Chironomus sp., Lumbricus sp., Melanoides sp., and Bellamya sp. Station 2 genus number obtained during the observation that there are 4 genera : Branchiura sp., Lumbricus sp., Limnodrilus sp., and Goniobasis sp. Station 3 genus number obtained during the observation that there are 5 genera : Branchiura sp, Lumbricus sp., Limnodrilus sp., Goniobasis sp., and Tubifex sp. Station 4 genus number obtained during the observation that there are 6 genera : Branchiura sp., Lumbricus sp. , Limnodrilus sp., Goniobasis sp., Chironomus sp., and Goniobasis sp. Type uniform distribution of each station is visible from the class Oligochaeta Branchiura sp., and Lumbricus sp. The percentage of the composition of each class is the Oligochaeta 79%, Gastropoda 17%, and Insects 4%. Oligochaeta has the highest percentage with 79%. The high percentage indicates the existence of a class Oligochaeta Belumai River has been polluted. Oligochaeta are a tolerant organisms and able to withstand environmental conditions containing high organic matter. Diversity of macrozoobenthos in Belumai River based on analysis of k-dominant curve shows that the diversity decreases in the downstream direction. seen from the station groupings based on the analysis of Bray-Curtis Dissimilarity for macrozoobenthos and Pearson for physico-chemical parameters, resulting in two dendrogram which shows similarities. Both the dendrogram showed distinct groupings that station 1 to station 2, 3, 4. The existence of these groups due to differences in the input
Keyword: Belumai River, river water quality, diversity of macrozoobenthos

Judul: Distribusi kemelimpahan makrozoobenthos sebagai indikator pemantauan dampak industri dan pemukiman di perairan sungai Deli Kotamadya Medan
Abstrak: Sungai Deli adalah salah satu sumberdaya perairan yang dimanfaatkan oleh masyarakat Kotamadya Medan untuk keper­luan rumah tangga antara lain tempat mandi, cuci dan kakus (MCK), keperluan domestik, pertanian, perikanan dan tempat pembuangan limbah industri. Akibat dari seluruh aktivitas di atas diduga telah terjadi penurunan kualitas air dari hulu sampai ke hilir Sungai Deli. Sungai Deli yang mengalir melintasi Kotamadya Medan ini mempunyai tiga anak sungai yaitu Sungai Babura, Mati, dan Sikambing dan Sungai Deli merupakan tempat bermuaranya ketiga anak sungai tersebut. Tujuan pene li tian adalah untuk mengkaj i, faktor apa yang cenderung mempengaruhi penurunan kualitas perairan sungai, keanekaragaman jenis makrozoobenthos dan untuk mengkaji indikator kualitas lingkungan dari kehidupan makrozoobenthos yang berada di sekitar aliran Sungai Deli tersebut. Penelitian ini dilaksanakan sejak bulan Nopember 1991 sampai Maret 1992, dengan dua musim yaitu musim hujan dan musim kemarau. Pengambilan contoh di lapangan yaitu se-banyak 4 kali dengan perincian dua periode pada saat musim hujan dan dua periode pada saat musim kemarau. Pengambilan contoh dilakukan pada 8 stasiun pengamatan. Pengamatan dan pengambi lan con toh me 1 iputi parameter f isika-kimiawi air serta makrozoobenthos. Parameter abiotik penentu kemelim­pahan makrozoobenthos dianalisis secara statistik dengan menggunakan Regresi Berganda. Pemantauan kualitas perair­an secara biologis digunakan model distribusi kemelimpahan spesies, indeks diversitas, analisis model multivarian, model grafik suksesi komunitas dan pengelompokan habitat berdasarkan biota. Hasil penelitian menunjukkan bahwa analisis terhadap kualitas air Sungai Deli dengan menggunakan Indeks Kuali- tas Lingkungan menurut Ott ( 197 8) ni lai IKL-nya berkisar an tar a 6 2. 9 3-84. 7 9 pada musim huj an I, 78. 22-89 .12 pada musim hujan II, 76.28-90.25 pada musim kemarau I dan 68.86-86.60 pada musim kemarau II. Nilai IKL Sungai Deli semakin kearah hilir semakin rendah. Namun nilai tersebut masih berada pada kategori sedang (stasiun VII), baik sampai sangat baik (stasiun I dan II) dst. ...
Keyword: Macrozoobenthos, Sungai Deli Kotamadya Medan

Judul: Konstruksi aritmetika kurva eliptik F(2m) supersingular dan non-supersingular untuk skema kunci publik ElGamal
Abstrak: Algoritme ElGamal adalah salah satu algoritme kunci publik dengan aritmetik modular p yang mempunyai struktur grip siklik Z(p). Tingkat keanaman algoritme ini terletak pada pemecahan masalah logaritme diskret dari Z(p). Akan tetapi, tingkat keamanan tadi tahun ke tahun semakin menurun yang disebabkan kemampuan pemecahan algoritme diskret semakin meningkat. Untuk memenuhi tingkat keamanan yang memadai dibutuhkan p yang cukup besar yang menyebabkan proses enkripsi dan dekripsi menjadi lambat.
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