Judul: Changes in NDVI as an Indicator of Vegetation Cover Change in Jambi Province: Implications to Rainfall
Abstrak: Jambi merupakan salah satu provinsi dengan tingkat deforestasi tinggi di Indonesia. Periode tahun 2013 hingga 2022 luas hutan berkurang sebanyak 688.358 hektar dengan dampak biogeofisik berupa perubahan tutupan vegetasi, fluks bahang, albedo dan suhu permukaan. Penelitian ini bertujuan menganalisis perubahan NDVI sebagai indikator perubahan tutupan vegetasi, perubahan fluks panas laten (LE) dan suhu permukaan (TS) dan pengaruhnya pada curah hujan. Metode Proportional Random Sampling digunakan dalam pengambilan titik sampel NDVI dan curah hujan. Pengolahan data citra Landsat 8 dilakukan menggunakan Google Earth Engine dan hasilnya dipetakan menggunakan ArcMap 10.3. Hasil penelitian menunjukkan bahwa dalam kurun waktu 2013-2022, nilai NDVI dan fluks panas laten mengalami penurunan dan nilai suhu permukaan mengalami peningkatan. Curah hujan tahunan di Provinsi Jambi berkurang 14,593 mm/tahun. Analisis korelasi antara NDVI dan curah hujan menunjukkan adanya korelasi positif dengan nilai koefisien determinasi (R2 ) sebesar 0,94 dan berpengaruh nyata dengan nilai p- value < 0,05. Tren curah hujan di Provinsi Jambi cenderung menurun akibat dari berkurangnya tutupan vegetasi yang ditunjukkan oleh nilai NDVI pada periode penelitian meskipun terdapat faktor lokal lain yang dapat memperngaruhi seperti suhu permukaan dan tekanan udara maupun faktor regional seperti angin, fenomena ENSO dan juga monsoon., Jambi is one province with a high deforestation rate in Indonesia. From 2013 to 2022, the forest area decreased 688.358 hectares with biogeophysical impacts like changes in vegetation coverage, heat fluxes, albedo and surface temperature. This study aims to analyze changes in NDVI as an indicator of vegetation cover change, changes in latent heat flux (LE) and surface temperature (TS) and the implications to rainfall. We used Proportional Random Sampling method in taking NDVI and rainfall sampling points. Landsat 8 image data processing were conducted using Google Earth Engine and the result were mapped using ArcMap 10.3. It was found that within period 2013-2022, NDVI and LE values decreased and TS values has increased. Annual rainfall in Jambi Province decreased 14,593 mm/year. The correlation between NDVI and rainfall shows a positive correlation with R 2 0,94 and has a significant effect with p-value < 0,05. The trend of rainfall in Jambi Province tends to decrease, we suspected as the result of a decrease in vegetation cover (indicated by NDVI value) within the period of study. In addition, there are other local and regional factors such as surface temperature, air pressure, ENSO and monsoon.
Keyword: curah hujan, fluks bahang laten, NDVI, suhu permukaan, tutupan lahan

Judul: Analysis of Normalized Difference Vegetation Index (NDVI), Surface Albedo, and Precipitation Distribution on Various Land Uses in Jambi Province
Abstrak: Proporsi terbesar kelas penggunaan lahan Kabupaten Muaro Jambi dan Kota Jambi adalah vegetasi yaitu sebesar 89% dari total luas area. Hal tersebut berkaitan dengan interaksi antara atmosfer dan permukaan yang dipengaruhi oleh kondisi dan variasi dari vegetasi di atas permukaan. Variasi vegetasi di atas permukaan mempengaruhi nilai albedo dan NDVI. Tujuan dari penelitan ini yaitu menganalisis distribusi sebaran albedo, NDVI, dan curah hujan juga menganalisis korelasi antara albedo, NDVI terhadap curah hujan. Proses pengolahan data spasial albedo dan NDVI menggunakan citra landsat-8 OLI/TIRS. Data citra telah terkoreksi geometrik, dan dikoreksi radiometrik dengan konversi ToA. Data curah hujan menggunakan data reanalisis yang dikoreksi dengan menggunakan koreksi bias metode rasio rata-rata. R2 dari koreksi bias menunjukkan nilai 0,45-0,60. Pola distribusi spasial albedo untuk tiap penggunaan lahan dari yang terrendah hingga tertinggi adalah hutan, perkebunan, pertanian, semak, dan lahan terbangun. Pola distribusi spasial NDVI dan curah hujan berbanding terbalik terhadap albedo. Korelasi lintas penggunaan lahan dari masing-masing variabel albedo terhadap curah hujan menunjukkan R2 sebesar 0,99, dan NDVI terhadap curah hujan menunjukkan R2 sebesar 0,97. Curah hujan meningkat seiring dengan meningkatnya NDVI dan menurunnya albedo, mengindikasikan kemungkinan lebih besarnya aliran massa udara basah dari permukaan yang lebih besar tutupan vegetasinya (ditunjukkan oleh nilai NDVI yang semakin besar) sehingga potensi pembentukan awan dan hujan semakin besar., Muaro Jambi and Jambi Regency’s largest proportion area is vegetation. It is about 89% of the total area. It is related to the interaction between atmosphere and land surface that influenced by the variations and conditions of vegetation above the land surface. The variations of vegetation above the land surface implicated the value of albedo and NDVI. The aim of this study is to analyze spatial distribution pattern of albedo, NDVI, and precipitation also analyze the correlation between albedo, NDVI and precipitation. Spatial data processing of albedo and NDVI using landsat-8 OLI/TIRS data. The data has been corrected geometrically, and corrected radiometrically with ToA conversion. The precipitation variable using reanalysis data, corrected with bias correction using the average ratio method. The results of R2 of average ratio bias correction is 0.45-0.60. The spatial distribution patterns of albedo for each land use class from the lowest to the highest are forest, plantation, cropland, shrubs, and settlements. The spatial distribution patterns of NDVI and precipitation are inversely related to albedo. The correlation between albedo to precipitation shows R2 0.99, and correlation between NDVI to precipitation shows R2 0.97. Surface energy balance fluxes have a direct dependence on available energy, and other parameters like albedo and NDVI. Precipitation increased with decreased albedo and increased NDVI, indicating the possibility of greater wet air mass flow from the underlying surface with greater vegetation cover (indicated by a larger NDVI value) and increasing the potency for cloud formation and rain.
Keyword: Cropland, forest, landsat-8 OLI/TIRS, plantation, settlements

Judul: Synthesis of Apatite - Chitosan Composite Using Duck Eggshell and Chitosan with Temperature and pH Control
Abstrak: Composite of apatite-chitosan was prepared by using chitosan as polymer matrix. Calcium phosphate was prepared from CaO and (NH4)2HPO4, which the ratio Ca : P had to be 1.67. Chitosan is produced by deacetilase from biopolymer chitin. Duck eggshell (95% CaCO3) as starting material was converted to be calcium oxide (CaO) through calcinations with temperature 1000oC for 5 hours. In-situ and ex-situ methods were prepared from apatite and chitosan (dissolved with acetate acid 2%). Calcium phosphate prepared for bone implantation, but it is too fragile and brittle to be implant into the body. So addition of chitosan can decrease crystalinity and increase mechanic characteristic (tougher). Composite apatite-chitosan was resulted by fast precipitation. Fast precipitation was held in a breaker glass with nitrogen atmosphere, under controlled temperature at 37oC and pH 7, in order to increase amount of hydroxyapatite. Precipitation with CaO which was dropped by (NH4)2HPO4. Hydroxyapatite and chitosan were appearing at samples with in-situ and ex-situ methods which indicating by peak matching of XRD (closed lattice parameter, crystal size), overlapping at FTIR spectra and supporting by SEM picture (homogenous and agglomerated particle). However, it still needs further research to examine biocompatibility osteoconductive degree of sample by in-vivo and in-vitro test.
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