Judul: Hujan asam dan perubahan kualitas air sumur di wilayah industri (studi kasus di Wilayah Industri Cibinong-Citeureup Kabupaten Bogor)
Abstrak: The industrial area of Cibinong-Citeureup Bogor is crowded with transportation, has dusty atmosphere, has many industries, and has been experienced acid rain in 2008. Total of industries are 2944 units and the population density is 4131 people km-2. About 75.63 % of people in this area consume well water for drinking. Acid rain intensity and distribution was studied to map and to calculate the rate of well water quality degradation. Well water quality was monitored from the year of 1995, 1999, 2001, 2006, 2008, and 2009. The quality of rain water was monitored from the year of 1999, 2001, 2006, 2008, and 2009. The parameters studied were: pH, NO3-, SO4=, Fe, and Ca. The rain water was collected from 16 locations for the first 30 minutes of rain fall onset. The well water was sampled from 16 locations. The result showed that the pattern of acid rain was distributed into two categories: The first, is the area that has experience continuous high intensity acid rain (pH<5.0) covering ±1800 ha, whilst the second is the area that has rarely experienced high intensity acid rain. In the first area category the acid rain has influenced the well water quality degradation. The pH of acid rain has influenced the well water acidity. The NO3- concentration in well water was increased significantly (Fcal 1.61<Ftable; P 0.193<α 0.05). On the contrary, the concentration of SO4= in well water decreases although was not significantly different (Fcal 0.73<Ttable , and P 0.540 > α0.05). Furthermore, the Fe and Ca of well water was increased significantly (P 0.049 for Fe and P 0.001 for Ca) from 1999 to 2009. In the second category area the acid rain has not influenced the well water quality.
Keyword: West Java, Water quality, Dry deposition, Wet deposition

Judul: Estimation of Rainwater Acidity Level based on CO2, SO2, and NO2 Concentration in Rural and Sub-Urban Area (Case Study: Bogor)
Abstrak: Hujan asam merupakan salah satu fenomena yang menunjukkan dampak pencemaran udara terhadap lingkungan. Tingkat keasaman air hujan dapat diketahui melalui pengukuran pH air hujan. Namun, observasi dan ketersediaan data tingkat keasaman air hujan masih sangat terbatas. Salah satu metode untuk mengetahui tingkat keasaman air hujan melalui pendugaan berdasarkan konsentrasi polutan. Penelitian ini bertujuan mengestimasi tingkat keasaman air hujan berdasarkan konsentrasi polutan CO2, SO2, dan NO2 di wilayah sub-urban dan rural. Titik sub-urban dalam penelitian ini adalah Baranangsiang, Kota Bogor, dan titik rural adalah Cibeureum, Puncak-Bogor. Metode yang digunakan adalah pendekatan hukum kimia Henry terkait kelarutan gas dalam air. Asumsi dalam penelitian ini bahwa CO2, SO2, dan NO2 diduga berpengaruh pada konsentrasi ion hidrogen (H+). Hasil penelitian menunjukkan wilayah sub-urban memiliki potensi tingkat keasaman air hujan yang lebih tinggi, yaitu berkisar dari 4 – 5, dibandingkan dengan wilayah rural, berkisar dari 4,5 – 5,5. Titik rural dan sub-urban menghasilkan nilai estimasi di bawah pH normal air hujan menunjukkan keduanya berpotensi untuk terjadi hujan asam, tetapi dengan tingkat keasaman yang berbeda. Perbandingan hasil estimasi dan data observasi tingkat keasaman air hujan di titik rural menunjukkan kesesuaian yang cukup baik dengan koefisien korelasi sebesar 0,49. Perbedaan hasil estimasi dan observasi pada periode Juni – September disebabkan kandungan kation yang dapat menetralkan air hujan, seperti Ca2+ dan NH4+. Perbedaan hasil estimasi dan observasi pada periode Februari – Mei disebabkan pengenceran akibat tingginya curah hujan., Acid rain is a phenomenon that shows the impact of air pollution on the environment. The acidity of rainwater can be determined by measuring the pH of rainwater. However, observation and availability of rainwater acidity data is still rare. One method to determine the acidity of rainwater is through estimation based on pollutant concentrations. This study aims to estimate the acidity of rainwater based on concentrations of CO2, SO2, and NO2 in sub-urban and rural areas. The sub-urban point in this study is Baranangsiang, Bogor City, and the rural point is Cibeureum, Puncak-Bogor. The method used is Henry's chemical law approach related to the solubility of gases in water. The assumption in this study is that CO2, SO2, and NO2 are thought to influence the concentration of hydrogen ions (H+). The results showed that sub-urban areas have a higher potential for acidity of rainwater, ranging from 4 to 5, compared to rural areas, ranging from 4.5 to 5.5. Rural and sub-urban points produce estimated values below the normal pH of rainwater indicating both have the potential for acid rain to occur, but with different acidity levels. Comparison of the estimation results and observation data on the acidity of rainwater at rural points shows a good match with a correlation coefficient of 0.49. The difference in the estimation and observation results in the June – September period is due to the content of cations that can neutralize rainwater, such as Ca2+ and NH4+. The difference in estimation and observation results in the February – May period is due to dilution due to high rainfall.
Keyword: acid rain, Henry's law, rural, sub-urban, wet deposition

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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