Coral reef monitoring in Panjang Island, Central Bangka

Bangka Island is the largest tin producer in Indonesia and since the granting of tin mining freedom in 2000, unconventional tin mining (TI) is increasingly prevalent. The existence of mining activities will directly or indirectly damage the environment both on land and at sea. Especially the high biodiversity of coral reef ecosystem. The purpose of this research was to analyze a map of the distribution of coral reef based on Sentinel 2A satellite imagery data. Analyze the extent of the coral reefs in shallow waters of Putri Island, and analyze of the condition coral reefs (percentage cover, mortality index and genus diversity) with using collaboration betwen the coral diving data and remote sensing data. Studies of changes in coral reef ecosystems have been ongoing since several decades ago. The combination of satellite imagery and aerial photographs is capable of making long-term and continuous observations on mapping and change detection. Remote sensing technology has several advantages overconventional sampling to monitor a large area in time almost simultaneously and continuously including the difficult to explore areas. This research was conducted with visual interpretation by using standard true color composite band (483) and false color composite band (843) of Sentinel 2A and also using lyzenga transformation. Estimation of coral reefs area based on result is 475,96 ha (2016) and decreased to 475 ha (2021). The condition of coral reefs at the research location is a good condition.

Kajian Perubahan Luasan untuk Prediksi Simpanan Karbon Ekosistem Mangrove di Desa Kaliwlingi, Kabupaten Brebes

Ekosistem mangrove memiliki potensi besar dalam penyerapan CO2 dari atmosfer. Jumlah kadar CO2 yang tersimpan pada ekosistem mangrove semakin berkurang seiring menyusutnya luasan ekosistem mangrove tersebut. Ekosistem mangrove Kabupaten Brebes diduga telah mengalami perubahan luasan sehingga berpengaruh terhadap jumlah CO2 yang terserap. Penelitian ini bertujuan untuk mengetahui perubahan luasan dan prediksi simpanan karbon ekosistem mangrove di Desa Kaliwlingi, Kabupaten Brebes. Penelitian ini dilakukan pada bulan Mei 2019 dengan menggunakan metode deskriptif. Citra yang digunakan adalah citra satelit Landsat tahun 1996, 2000, 2007, 2010, 2015, dan 2019. Pengolahan citra dilakukan dengan bantuan software Er Mapper 7.0 dan Arcmap 10.4.1. Tahapan identifikasi mangrove menggunakan komposit band RGB 564, kemudian dilakukan pemisahan obyek mangrove dan non mangrove dengan menggunakan metode unsupervised classification. Metode analisis kerapatan mangrove yang digunakan adalah algoritma NDVI. Perhitungan nilai kandungan biomassa berdasarkan rumus allometrik tiap spesies. Perubahan luasan ekosistem mangrove di Desa Kaliwlingi, Kabupaten Brebes tahun 1996 - 2019 berturut-turut adalah 51,84 ha, 114,30 ha, 43,29 ha, 163,62 ha, 286,38 ha dan 475,65 ha. Sedangkan prediksi nilai simpanan karbon total adalah ± 689,57 ton, ± 1474,18 ton, ± 541,07 ton, ± 2612,17 ton, ± 4324,36 ton, dan ± 6778,30 ton. Nilai simpanan karbon total pada ekosistem mangrove di Desa Kaliwlingi, Kabupaten Brebes meningkat seiring dengan bertambahnya luasan ekosistem mangrove tersebut. Mangrove ecosystems have great potential in absorbing CO2 from the atmosphere. The amount of CO2 stored in the mangrove ecosystem decreases as the area of the mangrove ecosystem shrinks. The mangrove ecosystem area of Brebes Regency was justified decreased as well as the CO2 absorption. This study aims to determine changes in the extent and predictions of carbon stock of mangrove ecosystems in Kaliwlingi village, Brebes Regency. This research was conducted in May 2019 using descriptive methods. The imagery used was Landsat satellite imagery in 1996, 2000, 2007, 2010, 2015 and 2019. Image processing was carried out with the help of Er Mapper 7.0 and Arcmap 10.4.1 software. The stages of mangrove identification using the RGB 564 composite band, then the separation of mangrove and non-mangrove objects was carried out using the unsupervised classification method. The mangrove density analysis method used was the NDVI algorithm. Calculation of biomass value based on the allometric formula for each species. Changes in the extent of mangrove ecosystems in Kaliwlingi village, Brebes Regency in 1996 - 2019 were 51.84 ha, 114.30 ha, 43.29 ha, 163.62 ha, 286.38 ha and 475.65 ha, respectively. While the predicted values of total carbon stock were ± 689,57 ton, ± 1474,18 ton, ± 541,07 ton, ± 2612,17 ton, ± 4324,36 ton, dan ± 6778,30 ton. The values of total carbon stock in the mangrove ecosystem in Kaliwlingi village, Brebes Regency was increased along with the expansion of the mangrove ecosystem.

Analisa Distribusi Spasial Vegetasi Mangrove di Desa Pantai Mekar Kecamatan Muara Gembong

Mangrove merupakan vegetasi yang tumbuh di wilayah pesisir dengan kemampuan beradaptasi baik secara morfologi dan fisiologi terhadap lingkungan. Ekosistem mangrove memiliki beragam peran diantaranya peranan ekologi, ekonomi dan sosial budaya. Penyusutan luas hutan mangrove yang terjadi di Kecamatan Muara Gembong menyebabkan penurunan kualitas ekosistem mangrove. Kegiatan rehabilitasi tidak berjalan secara maksimal akibat belum tersedianya peta tematik mangrove untuk menunjang kegiatan penanaman mangrove di wilayah Desa Pantai Mekar yang merupakan salah satu desa di wilayah Kecamatan Muara Gembong. Tujuan penelitian ini menganalisis sebaran mangrove, luas vegetasi mangrove dan persentase kategori tutupan vegetasi mangrove melalui pendekatan penginderaan jauh dan validasi lapangan. Citra yang digunakan pada penelitian ini yaitu citra satelit Sentinel 2A. Metode penginderaan jauh yang digunakan untuk mengetahui sebaran mangrove dengan perpaduan composite band dan supervised classification sedangkan untuk luas vegetasi mangrove dan persentase tutupan vegetasi mangrove menggunakan metode Normalized Difference Vegetation Index (NDVI). Metode validasi lapangan untuk tutupan vegetasi mangrove menggunakan hemispherical photography. Hasil penelitian menunjukan sebaran vegetasi mangrove di Desa Pantai Mekar tersebar di daerah ekowisata, wilayah sekitar sungai, daerah muara sungai, bekas tambak dan sekitar tambak dengan luas hutan mangrove sebesar 377,06 ha. Klasifikasi tutupan vegetasi mangrove terdiri dari 81,53 ha (21,62 %) kategori mangrove padat, 77,11 ha (20,45 %) kategori mangrove sedang dan 218,42 ha (57,93 %) kategori mangrove jarang. Mangrove is a tropical coastal vegetation that has the ability to adapt well morphologically and physiologically in the environment. Mangrove ecosystems have various of functions, including ecological, economical, and socio-culture functions. The extensive depreciation of mangrove forests that occurred in the District of Muara Gembong caused a decrease in the quality of the mangrove ecosystem. The rehabilitation activities have not run optimally, because there have not been any thematic maps to support mangrove planting activities in the Pantai Mekar Village area which is one of the villages in the Muara Gembong Subdistrict area. The purpose of this study is to analyze the distribution of mangroves, mangrove vegetation area and percentage of mangrove vegetation cover categories through remote sensing approach and field validation. The image used in this study is the Sentinel 2A satellite image. Remote sensing method used to determine the distribution of mangroves with a combination of composite band and supervised classification, while for the area of mangrove vegetation and the percentage of mangrove vegetation cover using the Normalized Difference Vegetation Index (NDVI). The field validation method for the mangrove vegetation cover uses hemispherical photography. The results showed that the distribution of the mangrove vegetation in Desa Pantai Mekar spread over the ecotourism areas, watershed, river estuaries, and aquaculture ponds with a total area of 377,06 hectares. The area is consisted of 81,53 hectares (21,62%) dense forest, 77,11 hectares (20,45%) medium dense forest, and 218,42 hectares (57,93%) sparse forest.

Defect Related Emission in Calcium Hydroxide: The Controversial Band at 780 cm−1

Calcium hydroxide, a crystal involved in the cycle of calcination and carbonation of calcium oxide, finds several applications from cultural heritage to the dentistry branch or to the construction industry. When excited at 1064 nm, Raman spectra of calcium hydroxide show a broad composite band peaked at about 780 cm−1, corresponding to 1170 nm. Since it is not observed with visible excitation, the origin of this band is debated, being assigned to some pre-existent luminescent impurities or some structural defect of the lime formed after the synthesis of the material. To shed light on the formation of this band, we synthetised the lime paste starting from pure calcite powders. The obtained fresh Ca(OH)2 samples did not show any band in the investigated range, irrespective of the laser excitation applied. A detailed analysis of the excitation and emission spectra in the near infrared region did not show the 1170 nm band, supporting the hypothesis of a post-synthesis origin. Thus, we carried out thermal treatments at different temperatures (90–500 °C) and under different environments (in air or under nitrogen flux) on synthesised fresh Ca(OH)2 powders. We also investigated the time evolution of the samples, monitoring the Raman spectra over 90 days after a specific treatment. The collected data support the hypothesis of a defect-related luminescence centre, whose formation depends on the temperature and environment of the treatment, which appears as a preferential site for the carbonation process of the calcium hydroxide. These results can be useful in the field of Cultural Heritage for dating purposes, and to determine the conservation state of Ca(OH)2 containing relics to prevent the possible activation of degradation processes.

Penajaman Citra Satelit Landsat 8 Menggunakan Transformasi Brovey

Intisari— Penajaman citra adalah teknik optimasi citra dengan cara mengkombinasi dua citra satelit dengan mengambil kelebihan yang dari tiap citra sehingga citra output memiliki kualitas spektral dan spasial yang baik. Penajaman citra dilakukan sebagai alternative untuk memudahkan pengenalan suatu objek, terlebih lagi untuk satelit Landsat mempunyai banyak band yang mampu dijadikan sampel untuk proses penajaman citra. Metode yang digunakan dalam penajaman citra salah satunya adalah Transformasi Brovey. Metode ini banyak digunakan karena sangat simple dan mudah dalam pembuatan algoritmanya. Band yang digunakan dalam proses penajaman citra yaitu composite band (red, green, dan blue) dengan pankromatik band dari satelit landsat 8. Hasil dari proses penajaman citra adalah citra dengan spectral yang tinggi didapat dari citra composite serta nilai spasial yang didapat dari citra pankromatik. Analisa hasil dari penajaman citra dengan metode Transformasi Brovey dilakukan dengan membandingkan kualitas dari citra truecolor sebelum ditajamkan dan citra yang sudah ditajamkan dengan cara menghitung nilai maksimun dan minimun dari band red, green dan blue, analisa nilai mean dan juga nilai standar deviasi dari masing-masing citra. Kata Kunci— Composite, Landsat 8, Penajaman Citra, Transformasi Brovey

Enhanced Photocatalytic Behavior of (GO/Cu2O) Composite with Cu2O Being Synthesized Through Green Route

Graphene oxide/Cuprous oxide (GO/Cu2O) composite is a visible light photocatalyst for the degradation of dyes. A simple and efficient approach for preparing GO/Cu2O composite adopted in this study involves reducing cuprous oxide precursors in the presence of graphene oxide using an aqueous solution of pulp derived from banana fruit. The GO/Cu2O composite was characterized by Fourier transform infrared spectroscopy (FT-IR), Diffused reflectance Ultraviolet visible spectroscopy (DRS UV-Vis), Raman spectroscopy and Field Emission Scanning electron microscopy (FE-SEM). Cu2O particles were distributed randomly on the graphene oxide sheets due to the template effect of GO. The results showed higher photocatalytic activity for the composite (band gap 2.13 eV), for the degradation of the organic dyes (Methylene blue and Rhodamine-B). The enhanced photocatalytic activity is due to effective charge transfer from GO to Cu2O, and high specific surface area which improves the effective separation of the generated electron–hole pairs. Our present study is inspired by a facile, low cost, green production of (GO/Cu2O) composite whose photocatalytic activity can be extended to degradation of all other water-born textile dyes.

The Changes in Vast Mangrove Area of Pantai Air Telang Protected Forest Banyuasin District using Landsat Imagery Data Time Series

This study aimed to obtain data about far-reaching changes on the total area of mangrove at Air Telang Beach Protected Forest through the interpretation of Landsat 7 imagery data using open source software (Ilwis 2000) in years 2000, 2003, 2006, 2009 and 2012. In the first phase, mangrove identification was conducted through cropped imagery data based on the research area which is path 124 raw 62 using RGB543 composite band. Then, mangrove and non-mangrove area are separated using unsupervised classification method. The next phase, mangrove density analysis is directed by applying NDVI formula. The results showed that the total area of mangrove has decreased over a period of 12 years by 10.72 % of total mangrove area on 2000 (7,968.54 ha) with 7,147.12 on 2012. Vegetation Index analysis shows high density mangrove is dominated although it continues to decrease, followed by increasing mangrove area with medium density.Keywords: Air Telang Beach Protected Forest, imagery data, mangrove total area, density.