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Copper and Lead Contamination in Sediment and Benthic Ecosystems of Sembilang National Park’s Coastal Region, South Sumatra Rozirwan; Ananta, Dio Alif; Khotimah, Nadila Nur; Putri, Wike Ayu Eka; Fauziyah; Dianysah, Gusti; Siregar, Yusni Ikhwan; Ramses; Isnaini; Melki; Aryawati, Riris; Agustriani, Fitri; Nugroho, Redho Yoga
Science and Technology Indonesia Vol. 10 No. 3 (2025): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2025.10.3.866-876

Abstract

Littoral zone often face environmental pressure due to anthropogenic activities, which can impact the quality of their ecosystem. This study analyzes the concentrations of copper (Cu) and lead (Pb) in sediments and benthic (Anadara granosa and Cerithidea cingulata). Sampling procedures were implemented during September 2022 across the aquatic habitats of Sembilang National Park, in South Sumatra Province, using the purposive sampling method. Sediment grain size and substrate type were analyzed using Shepard’s triangle. Metal detection using a spectrophotometric method based on atomic absorption. The results showed that the sediment fraction mostly consisted of clay, ranging from 92.03% to 94%. Cu concentrations in the sediment ranged from 5.01±0.017 to 5.71±0 mg/kg, while Pb concentrations ranged from 10.5±0.195 to 11.51±0.395 mg/kg. In the benthic, Cu concentrations ranged from 0.0037±0.00005773 to 0.0147±0.00000346 mg/kg, and Pb concentrations ranged from 0.0001±0.000227 to 0.005±0 mg/kg. According to the statistical evaluation testing via independent sample t-test showed that heavy metals differed significantly (p <0.05) between sediment and benthic compartments. These results show that the environmental quality in Sembilang National Park is still comparatively well maintained and within current quality requirements, despite certain activities that have the potential to pollute the environment. To guarantee the long-term viability of this area, it is advised that environmental quality be frequently monitored as a mitigation action.
Heavy Metal Pb, Cu, and Cd Pollution in Water and Sediment Due to Anthropogenic Activities Along the Musi River, South Sumatra Wahyudi, Wahyudi; Rozirwan, Rozirwan; Putri, Wike Ayu Eka
Jurnal Penelitian Sains Vol 27, No 1 (2025)
Publisher : Faculty of Mathtmatics and Natural Sciences

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.56064/jps.v27i1.1168

Abstract

Human activities along river flows can increase the potential for heavy metal pollution, which risks reducing water quality, polluting sediments, and threatening the sustainability of aquatic ecosystems. This research aims to evaluate the distribution of heavy metal pollution in water and sediment in the Musi River, which is affected by various anthropogenic activities. Samples for heavy metal analysis were collected from four clusters of observation locations. The heavy metal parameters tested included Cd, Cu, and Pb, which were analyzed using the wet digestion method and measured with an Atomic Absorption Spectrophotometer (AAS). The resulting heavy metal contaminations in sediment were much higher than in water, with Pb having the highest concentration in both matrices. Pb concentrations in sediment ranged from 11.845 to 15.301 mg/kg, while in water they ranged from 0.0791 to 0.0801 mg/L. Cu has more varied concentrations, with the highest value in Cluster 4 sediment of 9.518 mg/kg and water of 0.0160 mg/L. Meanwhile, Cd has a low but significant concentration, with values in sediment ranging from 0.130 to 0.315 mg/kg and in water from 0.0084 to 0.0101 mg/L. This heavy metal pollution shows that sediment functions as the main reservoir for heavy metals due to bioadsorption and precipitation processes from the water column. The implications of these results emphasize the importance of regular environmental monitoring and mitigation of pollution sources to prevent further impacts on the stability of coastal ecosystem.
Screening and Profiling of Antioxidant Activity in Mud Crab (Scylla Serrata) from Banyuasin Waters Rozirwan, Rozirwan; Lestari, Ning Intan; Winarta, Yoga; Isnaini, Isnaini; Putri, Wike Ayu Eka; Hendri, Muhammad; Ulqodry, Tengku Zia; Fauziyah, Fauziyah; Melki, Melki; Nugroho, Redho Yoga; Mohamed, Che Abd Rahim
ILMU KELAUTAN: Indonesian Journal of Marine Sciences Vol 30, No 3 (2025): Ilmu Kelautan
Publisher : Marine Science Department Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ik.ijms.30.3.438-452

Abstract

Mangrove crab (Scylla serrata) as one of the crustacean species, has a variety of bioactive compounds that can be utilized in the field of pharmacology. Antioxidant compounds act as therapeutic agents against degenerative diseases. Banyuasin waters have mangrove vegetation with associated marine organisms that have the potential to be studied for bioactive compounds. This study aims to identify the phytochemical profile quantitatively and qualitatively, samples were collected from mud flats near mangrove ecosystems in Banyuasin waters, South Sumatra. Samples were tested for antioxidant activity using the DPPH test, and IC50 values, qualitative phytochemical identification, and phytochemical profiles were calculated using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Based on the results of antioxidant testing, the IC50 value of S. serrata extract is 2.25 ppm, the sample is included in the category of very strong antioxidants. Phytochemical test results showed that the compound is thought to contain antioxidant activity from flavonoids and triterpenoids. GC-MS analysis detected major compound groups of alkaloids, purines, and vitamins. Minor compound groups detected amines, terpenoids, monosaccharides, amino acids, fatty acids, silanes, formamides, heterocycles, carboxylic acids, aminoglycosides, naphthalene derivatives, nitriles, amides, glycosides, and peptides. S. serrata extract shows very strong antioxidant activity, with major compounds such as alkaloids, purines, and vitamins. S. serrata extract detected compounds that have been reported as anti-inflammatory, anticancer, antimicrobial, and antiviral. These findings highlight the pharmaceutical potential of S. serrata as a source of bioactive compounds. The results of this study provide valuable information for the development of alternative medicines derived from marine organisms.
Persebaran Mikroplastik di Lintas Ekosistem Sumatera Selatan Purwiyanto, Anna Ida Sunaryo; Putri, Wike Ayu Eka; Melki, Melki; Barus, Beta Susanto; Suteja, Yulianto
Buletin Oseanografi Marina Vol 14, No 3 (2025): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v14i3.75654

Abstract

Penelitian ini mengkaji keberadaan dan distribusi mikroplastik di muara dan sepanjang Sungai Musi di Sumatera Selatan, Indonesia—suatu kawasan yang terdampak berat oleh pencemaran industri, domestik, dan pertanian. Sampel diambil dari lima stasiun, dengan hasil menunjukkan rata-rata konsentrasi mikroplastik sebesar 33,8 partikel/m3. Konsentrasi tertinggi ditemukan di pertemuan Sungai Upang, kemungkinan akibat limpasan perkotaan dan buangan industri, sementara konsentrasi terendah terdeteksi di sekitar Jembatan Ampera dan Pulau Kemaro, di mana turbulensi air lokal dapat mendorong terjadinya sedimentasi mikroplastik. Mikroplastik yang teridentifikasi didominasi oleh fragmen (77,5%) dan serat (22,5%), dengan sebagian besar partikel berada dalam kisaran ukuran 301–500 µm. Jenis polimer yang paling dominan adalah Low-Density Polyethylene (LDPE), yang umumnya berasal dari limbah kemasan konsumen. Temuan ini menegaskan peran Sungai Musi sebagai jalur transportasi mikroplastik dari daratan menuju ekosistem laut, yang berpotensi menimbulkan risiko besar terhadap keanekaragaman hayati akuatik dan rantai makanan. Selain merusak habitat perairan, mikroplastik juga dapat menjadi media pembawa logam berat dan zat beracun lainnya, sehingga memperparah dampak ekologisnya.
Logam Berat Cd di Sungai Musi Bagian Hilir, Sumatera Selatan Putri, Wike Ayu Eka; Purwiyanto, Anna Ida Sunaryo; Diansyah, Gusti; Rozirwan, Rozirwan; Fauziyah, Fauziyah; Agustriani, Fitri; Haryati, Ani; Gusri, Ariqoh Athallah
Buletin Oseanografi Marina Vol 13, No 1 (2024): Buletin Oseanografi Marina
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/buloma.v13i1.56751

Abstract

Pemanfaatan daerah aliran sungai seringkali memberikan dampak negatif terhadap kualitas perairan. Kondisi ini pada akhirnya akan berdampak terhadap keamanan pangan yang berasal dari wilayah tersebut. Salah satu komponen bahan pencemar yang umum ditemukan di perairan dan menjadi ancaman bagi keamanan pangan adalah logam berat Cd. Penelitian bertujuan mengetahui konsentrasi logam berat Cd pada beberapa komponen ekosistem yang ada di Sungai Musi bagian hilir meliputi air, sedimen dan tiga organ ikan (insang, hati dan daging). Ikan yang menjadi objek penelitian adalah empat jenis ikan yang umum tertangkap meliputi ikan Juaro (Pangasius polyuranodon), ikan Sembilang (Paraplotosus albilabris), ikan Seluang (Rasbora sp) dan ikan Belanak (Mugil chepalus). Sampel air dan sedimen diambil dari sekitar Sungai Musi bagian hilir yang dibagi menjadi delapan (8) stasiun penelitian selama periode Maret, Mei dan November 2018. Adapun sampel ikan diambil dari nelayan sekitar yang menangkap ikan di kawasan tersebut. Sampel dianalisa merujuk pada metode USEPA 30050B dan dianalisa menggunakan AAS. Hasil penelitian menunjukkan bahwa konsentrasi rata-rata logam berat Cd pada sampel air kecil dari 0,001 mg/l dan pada sedimen berkisar antara 0,223-0,419 mg/kg. Konsentrasi rata-rata Cd pada organ hati, insang dan daging ikan Seluang adalah 0,117, 0,034 dan 0,021 mg/kg, ikan Juaro 0,059, 0,051 dan 0,027 mg/kg, ikan Belanak 0,096, 0,031 dan 0,025 mg/kg, ikan Sembilang 0,102, 0,046 dan 0,032 mg/kg. Konsentrasi logam berat Cd pada sampel air, sedimen dan daging ikan Seluang, ikan Juaro, ikan Belanak dan ikan Sembilang masih dibawah baku mutu dan ambang batas yang ditetapkan.   Utilization of river often has a negative impact on water quality. This condition will influence on the security of food originating from this area. One component of pollutants that is commonly found in waters and poses a threat to food safety is heavy metal such as Cd. The research aims to determine the concentration of the heavy metal Cd in several ecosystem components in the Musi River Estuary, including water, sediment and three fish organs (gills, liver and meat). Object of this research are four types of fish that are commonly caught, such as Juaro fish (Pangasius polyuranodon), Sembilang fish (Paraplotosus albilabris), Seluang fish (Rasbora sp) and Belanak fish (Mugil chepalus). Water and sediment samples were taken from around the Musi River downstream, divided into eight (8) research stations during March, May and November 2018. Fish samples were taken from local fishermen who caught fish in the area. Samples were analyzed using the USEPA 30050B and AAS (atomic absorption spectrophotometer). The results showed that the average concentration of the heavy metal Cd in water samples was less than 0.001 mg/l, in sediments ranging from 0.223 to 0.419 mg/kg. The average concentration of Cd in the liver, gills and muscle of Seluang fish was 0.117, 0.034 and 0.021 mg/kg, Juaro fish 0.059, 0.051 and 0.027 mg/kg, Belanak fish 0.096, 0.031 and 0.025 mg/kg, Sembilang fish 0.102, 0.046 and 0.032 mg/kg. The concentration of the heavy metal Cd in samples of water, sediment and muscles of Seluang, Juaro, Belanak and Sembilang fish was still below some specified quality standards.
PERUBAHAN GARIS PANTAI DI PERAIRAN MUARA BANYUASIN KAITANNYA DENGAN SEDIMENTASI Pratama, M. Andrian Putra; Barus, Beta Susanto; Putri, Wike Ayu Eka
Jurnal Ilmu dan Teknologi Kelautan Tropis Vol. 12 No. 1 (2020): Jurnal Ilmu dan Teknologi Kelautan Tropis
Publisher : Department of Marine Science and Technology, Faculty of Fisheries and Marine Science, IPB University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (899.514 KB) | DOI: 10.29244/jitkt.v12i1.28276

Abstract

The estuary waters of the Banyuasin River are one of the river estuary waters that is affected by the sedimentation process. This area gets a big influence from land input. This study aims to analyze the changes in the coastline in Muara Banyuasin Waters, South Sumatra associated with sediment characteristics and sedimentation rates. This research was conducted in October 2018 and sampling was carried out by installing sediment traps for 14 days. Samples were taken once a week and then the rate of sediment accumulation were calculated. Analysis of coastline changes is done using image data processing with a span of 5 years using ErMapper 7.0 software. The results of image data processing are discussed descriptively with sedimentation rates and sediment characteristics. The results showed that the predominant characteristics of sediments were clay and silt with sediment accumulation rates ranging from 2.06 kg/m2/day-6.55 kg/m2/day. The estuary waters of the Banyuasin River undergo a change in coastline in the form of sedimentation and abrasion. Sedimentation occurred at 6 stations while abrasion occurred at 2 stations. Coastline changes are ranged ±33 m-±322 m. Stations that experience high coastline changes are characterized by high sedimentation rates and subtle dominant substrate types (silty clay). Whereas areas that experience low coastline changes have low sedimentation rates with coarser substrate types (sandy silt).
Status Cemaran Logam Berat pada Sedimen Ekosistem Mangrove di Muara Sungai Banyuasin Novitasari, Tri Ayu; Ulqodry, Tengku Zia; Putri, Wike Ayu Eka; Diansyah, Gusti; Melki, Melki; Barus, Beta Susanto; Aryawati, Riris; Hendri, Muhammad
Indonesian Journal of Oceanography Vol 7, No 4 (2025): Indonesian Journal of Oceanography
Publisher : University of Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/ijoce.v7i4.29506

Abstract

Mangrove merupakan ekosistem pesisir yang penting karena mampu melindungi garis pantai, menyerap karbon, menyediakan habitat bagi biota, serta berperan sebagai penyaring polutan. Namun, tekanan aktivitas manusia di wilayah pesisir, seperti keberadaan pelabuhan, aktivitas perikanan, dan masukan limbah domestik dari daratan, dapat berkontribusi terhadap masukan logam berat baik di air maupun terakumulasi dalam sedimen. Penelitian ini bertujuan mengevaluasi status cemaran Pb dan Cu pada sedimen mangrove di Muara Sungai Banyuasin yang berdekatan dengan Pelabuhan Tanjung Api-api. Pengukuran konsentrasi logam berat dilakukan dengan metode Flame Atomic Absorption Spectrophotometry. Rata-rata kandungan Pb (20,71–21,61 mg/kg) dan Cu (10,81–10,99 mg/kg) masih berada di bawah ambang batas baku mutu lingkungan (Pb 50 mg/kg; Cu 65 mg/kg). Nilai Faktor Kontaminasi menunjukkan Pb termasuk kategori sedang, dan Cu tergolong rendah. Nilai Indeks Geoakumulasi ≤ 0 menunjukkan sedimen berada pada kondisi tidak tercemar dan Indeks Beban Pencemaran > 0–2 mengindikasikan berada dalam kondisi tercemar ringan. Secara keseluruhan, kualitas sedimen di Muara Sungai Banyuasin tidak menimbulkan risiko signifikan terhadap biota perairan, serta menunjukkan peran penting mangrove sebagai penahan akumulasi logam berat. Hasil penelitian ini memberikan dasar ilmiah bagi pengelolaan lingkungan pesisir, khususnya sebagai acuan dalam pemantauan kualitas sedimen dan pencegahan potensi pencemaran logam berat di sekitar pelabuhan.
Pelatihan Pembuatan Biskuit Gurih Berkolagen dari Limbah Kerang untuk Meningkatkan Ekonomi Pesisir Rozirwan Rozirwan; Yoga Winarta; Wike Ayu Eka Putri; Muhammad Nur; Gusti Diansyah; Redho Yoga Nugroho
Jurnal Altifani Penelitian dan Pengabdian kepada Masyarakat Vol. 6 No. 2 (2026): Maret 2026 - Jurnal Altifani Penelitian dan Pengabdian kepada Masyarakat
Publisher : Indonesian Scientific Journal

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59395/altifani.v6i2.1012

Abstract

Desa Sungsang IV merupakan wilayah pesisir penghasil kerang darah, namun limbah cangkang kerang belum dimanfaatkan secara optimal. Program ini bertujuan mentransfer teknologi pengolahan limbah menjadi kolagen, meningkatkan keterampilan masyarakat dalam pembuatan crackers kolagen sebagai pangan fungsional, serta memperkuat pengetahuan pemasaran dan kewirausahaan. Pelatihan dilaksanakan pada 18 Oktober 2025 dengan 35 peserta yang didominasi ibu rumah tangga. Hasil evaluasi pre–post menunjukkan peningkatan pengetahuan signifikan, terutama pada pemahaman manfaat kolagen, proses produksi, dan peluang pasar. Uji organoleptik menunjukkan produk diterima baik, dengan tingkat kesukaan tinggi pada tekstur, rasa, dan kerenyahan. Peserta juga memilih kemasan 50 g seharga Rp8.000 sebagai opsi paling menarik. Secara keseluruhan, kegiatan ini meningkatkan literasi teknologi pangan dan membuka peluang ekonomi berbasis blue circular economy.
Peningkatan Literasi dan Minat Studi Kelautan Siswa SMA melalui Edukasi Penyelaman Scuba Redho Yoga Nugroho; Riris Aryawati; Muhammad Hendri; Tengku Zia Ulqodry; Wike Ayu Eka Putri; Rozirwan Rozirwan
Jurnal Altifani Penelitian dan Pengabdian kepada Masyarakat Vol. 6 No. 2 (2026): Maret 2026 - Jurnal Altifani Penelitian dan Pengabdian kepada Masyarakat
Publisher : Indonesian Scientific Journal

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59395/altifani.v6i2.1106

Abstract

Rendahnya minat siswa SMA untuk melanjutkan studi di bidang Ilmu Kelautan menjadi tantangan di tengah besarnya potensi sumber daya laut Sumatera Selatan. Hal ini disebabkan oleh kurangnya informasi akurat mengenai prospek karir dan minimnya pemahaman mengenai teknik eksplorasi bawah air seperti penyelaman. Kegiatan pengabdian ini bertujuan untuk meningkatkan literasi dan minat siswa SMA di Kecamatan Tanjung Batu melalui edukasi dunia selam. Metode pelaksanaan meliputi visitasi, sosialisasi teori, peragaan alat selam, serta evaluasi melalui pre-test dan post-test. Hasil kegiatan menunjukkan adanya peningkatan pemahaman siswa secara signifikan terhadap fungsi peralatan selam dan peran pentingnya dalam riset kelautan. Antusiasme tinggi peserta terlihat saat praktik penggunaan alat, yang berimplikasi pada meningkatnya minat mereka terhadap Jurusan Ilmu Kelautan. 
Zinc (Zn) Accumulation in Mantis Shrimp (Harpiosquilla raphidea) from Sungsang, Banyuasin Syekhan, Ryan; Putri, Wike Ayu Eka; Aryawati, Riris; Barus, Beta Susanto; Agustriani, Fitri; Melki, Melki
Jurnal Biologi Tropis Vol. 26 No. 2 (2026): April - Juni
Publisher : Biology Education Study Program, Faculty of Teacher Training and Education, University of Mataram, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jbt.v26i2.11522

Abstract

The Sungsang area in the Musi River estuary is an important fishing ground that is potentially exposed to zinc (Zn) contamination due to intensive anthropogenic activities. This study aimed to analyze Zn accumulation in mantis shrimp (Harpiosquilla raphidea) and to evaluate its consumption safety. Samples were collected from local collectors and analyzed using flame atomic absorption spectrophotometry in accordance with SNI 2354-13:2014. The results showed that Zn concentrations ranged from 20.24 to 21.27 mg/kg, with an average of 20.70 mg/kg, remaining below the maximum permissible limit established by Dirjen POM (1989). Risk assessment based on estimated intake indicated that Zn exposure from mantis shrimp consumption is within safe limits for humans. Overall, these findings confirm that mantis shrimp from Sungsang are safe for consumption with respect to Zn contamination. This study provides scientific evidence for food safety assessment and underscores the need for continuous monitoring of heavy metal contamination to support sustainable coastal resource management.
Co-Authors Ade Siswanto Akdhia Besta Sari Amelia Fitriani, Amelia Ananta, Dio Alif Andrian Saputra Andrian Saputra Ani Haryati, Ani Anna Ida Sunaryo Purwiyanto Anna Ida Sunaryo Purwiyanto Anna Ida Sunaryo Purwiyanto Anna Ida Sunaryo Purwiyanto Anna Ida Sunaryo Purwiyanto Anna Ida Sunaryo Purwiyanto Anna Ida Sunaryo Purwiyanto Annisa Agustina Kurnia Putri Apon Zaenal Mustopa Aranxa, Virly Ariqoh Athallah Gusri Barus, Beta Susanto Berliana Iksy Della Beta Susanto Barus Che Abd Rahim Mohamed De Karo, Fransiskus Desmarinda, Jecika Dianysah, Gusti Dietriech Geoffrey Bengen Dika Ardila Diny Novita Sari Harahap Elyakim Sitorus Etty Riani Fajri, M. Awaluddin FAUZIYAH Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fauziyah Fikriyya, Nabela Fitri Agustriani Fitri Meiriyani Gusri, Ariqoh Athallah Gusti Diansyah Gusti Diansyah Gusti Diansyah Gusti Diansyah Gusti Diansyah Harahap, Diny Novita Sari Hartoni Hartoni Hartoni HEDI INDRA JANUAR Heron Surbakti Ida Riyanti Indra Yustian Isnaini Isnaini Isnaini . Jeni Meiyerani Khotimah, Nadila Nur Kurniawan, Mardian Candra Latupeirissa, Cherokee Mikha-El Lestari, Ning Intan Liana, Anjar Puteri Lidya Grace Lidya Grace Lilik Maslukah M. Awaluddin Fajri M. Hendri M. Yosi Prasetyo Mardian Candra Kurniawan Mei Ida Susanti Meiriyani, Fitri Meiyerani, Jeni Melki Melki , Melki Melki Melki Melki Melki Melki Moh. Muhaemin Moh. Muhaemin Mohamed, Che Abd Rahim Muhamad Nur Muhammad Hendri Muhammad Hendri Muhammad Nur Muhtadi Muhtadi Muhtadi Nadila Nur Khotimah Nadila Nur Khotimah Nidia Nova Riena Ningsih, Ellis Nurjuliasti Novi Anggraini Novi Angraini Novitasari, Tri Ayu Pratama, M. Andrian Putra Prihatiningsih, Isnaini Rahmad Purnama Rahmad Purnama, Rahmad Raihan, Muhammad Ramadhian, M. Zalfa Ramses Redho Yoga Nugroho Renita Tri Wahyuni Rezi Apri Rezi Apri Ria Ariana Riena, Nidia Nova Riris Aryawati Rozirwan Rozirwan . RR. Ella Evrita Hestiandari Santeri, Tiara Sarno . Siddik, Judistira Siswahyudianto Suai Batul Aslamiah Syakira Nurrachman Fadillah Syekhan, Ryan Tengku Zia Ulqodry Tengku Zia Ulqodry Tjahjo Winanto, Tjahjo Tri Prartono Wahyudi Wahyudi Widiya Nopita Sari Winarta, Yoga Yoga Winarta Yuanita Windusari Yulianto Suteja Yulianto Suteja Yundari, Yundari Yusni Ikhwan Siregar