Judul: Pengukuran fraksi leaching nuklida 228th dan 226Ra yang terkandung dalam kerak air dari industri minyak bumi
Abstrak: Kegiatan industri penambangan minyak dapat menghasilkan TENORM (unsur radioaktif alamiah yang terkonsentrasi pada limbah) berupa kerak air. Kerak air yang mengendap pada alat-alat produksi seperti tubular, welhead, valves, pump dan separator mengandung radionuklida yangbervariasi dengan konsentrasi cukup besar.
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Judul: Pengukuran fraksi leaching radionuklida alami 228Th dan 226ra dalam Tin Slag dan Copper slag
Abstrak: Penggunaan material sandblasting berupa tin slag dan copper slag berpotensi memberikan dampak radiologi berupa paparan radiasi eksternal maupun internal dari TENORM yang terkandung dalam material tersebut. Pengelolaan limbah sandblasting yang tidak tepat dapat menyebabkan ter-leaching-nya radionuklida-radionuklida TENORM ke lingkungan sehingga menimbulkan pencemaran terhadap air tanah, sungai dan sumber air lainnya. Berdasarkan hasil penelitian, konsentrasi 228Th yang terkandung pada tin slag sebesar 17127.82 Bq/kg sedangkan konsentrasi 226Ra sebesar 4629.09 Bq/kg. Nilai yang lebih rendah didapat pada pengukuran konsentrasi untuk nuklida copper slag, yaitu untuk 228Th sebesar 341.51 Bq/kg dan 226Ra sebesar 148.44 Bq/kg. Tingginya konsentrasi suatu nuklida dalam sampel padat tidak mengakibatkan konsentrasi suatu nuklida dalam sampel cair hasil proses leaching juga tinggi. Hal ini dapat terlihat pada nilai konsentrasi 226Ra pada sampel cair tin slag yang berkisar antara 0.98-2.44 Bq/l, sedangkan pada copper slag berkisar antara 1.03-2.32 Bq/l. Faktor pereduksian ukuran partikel dari 18 mesh menjadi 35 dan 60 mesh mempengaruhi proses leaching. Untuk konsentrasi 228Th pada tin slag berkisar antara 0.09-0.2 Bq/l sedangkan pada copper slag berkisar antara tidak terdeteksi hingga 0.03 Bq/l. Perbedaan nilai konsentrasi 226Ra dan 228Th dikarenakan radium bersifat lebih mudah larut dibandingkan dengan thorium. Fraksi leaching tin slag lebih kecil dari fraksi leaching copper slag disebabkan sifat kimia dari Cu yang terdapat dalam copper slag lebih mudah bereaksi dengan bahan kimia (asam) bila dibandingkan dengan Sn yang terdapat pada tin slag. Fraksi leaching 228Th pada sampel tin slag antara 0.004 – 0.01 %/hari dan fraksi leaching 226Ra antara 0.2 – 0.6 %/hari. Sedangkan fraksi leaching 228Th pada sampel copper slag antara tidak terdeteksi hingga 0.1 dan fraksi leaching 226Ra antara 7-17. 9%/hari.
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Judul: Pemoposan sebagai Bukti Taksonomi Jenis-jenis Diospyros (Ebenaceae)
Abstrak: People tend to use generative structures for plant identification. Nevertheless, generative structure availibility limits the identification practice for a plant with once-a-year fruit-bearing-phase, such as Diospyros L. Being vegetative characters, leaf flushing are rarely used for plant identification so that they have not been explored as a taxonomic evidence. In this paper, leaf flushings and their taxonomic implication were studied using eight species of Diospyros grown in Ecopark of Cibinong Science Center LIPI, Bogor. This study explored Diospyros leaf flushing, including the following: 1) morphological developments, 2) phenology, 3) morphological variations, 4) taxonomic implication, and 5) phenetic relationships. Morphological and phenological data was observed on eight species of Diospyros with 22 qualified individual trees. Data obtained then descriptively and phenetically analized. Arrested growth in the development of Diospyros bud produce a rhythmic growth. After a dormant period, bud broke and produced a flushing set before finally back to its dormancy. Diospyros flushing set was usually distinguishable from the previous one by cataphyll scars at the twigs and the pattern of phytomer in a flushing set (leaf size, the length internodus and petiole), except on D. buxifolia which the phytomer was uniform and the cataphylls were very small and sometimes absent. Dorsal cataphyll only found in D. jaherii. The presence of small reduced leaf due to an arrested growth also can be used to indicate the base of flushing set in D. blancoi dan D. jaherii. The time of bud broken was not simultaneous in all Diospyros species, all individual trees within the same species, even in all buds of an individual tree under similar external condition. Diospyros have a seasonal growth pattern, except for D. jaherii. A mature flushing set was formed in 40-55 days. Leaves of Diospyros observed were arranged alternately and have equitant vernation. Leaf flushing provided 39 characters (included bud, young leaves, mature leaves, and flushing set characters) that can be used as taxonomic evidence for distinguishing eight species of Diospyros observed. A determination key for these species solely based on leaf flushing characters is presented. Dendrogram obtained showed that leaf flushing characters were capable to divide individuals observed as well as their species at the coefficient of similarity 76%. The most similar species were D. blancoi and D. celebica (74%). Both of them are belongs to subgenus Eudiospyros (L.) Bakh., section Ebenaster Bakh. The cophenetic correlation value obtained was 0,98 or very good fit (Rohlf 1998). Two principal coordinate analysis used shows the diversity of 26,79% and divided Diospyros into three groups. Group I contained D.malabarica, D. beccarioides, D. cauliflora and D. pilosanthera. Group II cotained D. blancoi, D. celebica dan D. jaherii. Group III contained D. buxifolia. Flushing characters seems to be varied and can be used as field identification of Diospyros observed. Thus, leaf flushing was proved capable as a taxonomic evidence for Diospyros species observed.
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