Judul: Kandungan Nitrat dan Timbal pada Tanah dan Kangkung yang Diberi Pelakuan Air Limbah
Abstrak: Bare land is usually utilized by farmer staying in cities for growing horticulture. Generally they use river and ditch water as an irrigation source. The use of contaminated river and ditch water to irrigate plants causes the contaminative agent to be absorbed by plants and it can endanger human body if human consumes the plants. To know the contamination level, a measurement of lead and nitrate substances contained in water, soil and plants were carried out. However, consentration of lead in the water (including Municipal Water Company, river and ditch water) was unmeasured. It was because lead substances which came from vehicles fumes was not soluble in water. It was found that the nitrate level in water was about 0.60-1.98 ppm. That level was still below the standard level of water quality determined by The Ministry of Environmental Affairs (2001) which is 10 ppm for the 1st and 2nd class, and 20 ppm for the 3rd and 4th class. The lead level was found at about 6.90-56.56 ppm, whereas the safe lead contained in soil is about 20 ppm (Davies, 1995). Nitrate contained in soil is found at the level point of 1721.67-3347.85 ppm. The nitrate level in soil is not only influenced by the watering activities but also fertilizing activities. The lead level contained in plants was found at about 2.39-5.34 ppm, while the safe level of leads is 0.5-3 (Suhendrayatna). Nitrate level which was found in kangkung (kind of leafy vegetables growing in water) was found at 39492.45-54922.95 ppm. The cause of the high amount of nitrate in kangkung is that kangkung is included in Angiospermae and Spinacia plant which have an ability to accumulate a large number of nitrate in their body. Based on the measurement of lead level in water, it is concluded that water is not a contaminative agent of lead toward plants. Lead contained by soil and plants came from lead particles of vehicles fumes which fall on the surface of soil and leaves. Lead that directly falls down on the surface of leaves is mostly absorbed and enter the leaves tissues. It is as the consequences of the large size of stomata compare to the lead particles. The high level of nitrate in many vegetables causes the high amount of nitrate that flows in human body. According to Joel Petterson research, 60% of nitrate in human body will be secreted by urine.
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Judul: Pemanfaatan Air Lindi dari Proses Pengomposan sebagai Nutrisi Tanaman
Abstrak: Pertumbuhan penduduk di perkotaan yang meningkat mengakibatkan produksi limbah padat terus meningkat. Tumpukan sampah yang dibuang oleh masyarakat menghasilkan lindi yang berdampak negatif bagi lingkungan sekitar. Penelitian ini bertujuan menganalisis kualitas air lindi dari proses pengomposan dan menganalisis kualitas tanaman kangkung dengan aplikasi lindi sebagai nutrisinya. Kangkung ditanam menggunakan sistem hidroponik rakit apung dengan persentase aplikasi air lindi sebagai nutrisi sebesar 30%, 40%, 50%, dan 60%. Air lindi dibedakan sesuai umur pemanenan air lindi yaitu hari ke 1-7, 8- 14, 15-21, dan 1-21. Hasil uji air lindi menunjukkan kualitasnya belum memenuhi baku mutu berdasarkan Peraturan Menteri Pertanian Nomor 70 Tahun 2011. Tanaman kangkung yang diberi air lindi, yang dibudidayakan secara hidroponik dan dengan media tanah jenis aluvial, andisol, podsolik merah kuning latosol, regosol, dan latosol menghasilkan kualitas yang tidak layak konsumsi berdasarkan bobot segar tanaman kangkung, kandungan logam berat pada kangkung, dan penampakan fisik tanaman kangkung.
Keyword: air lindi, hidroponik, kangkung, nutrisi, pengomposan

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology