We present a unique water column data set of dissolved inorganic carbon (DIC) and total alkalinity (TAlk) from a cruise to the western Indonesian Seas during the southeast monsoon, covering the Karimata Strait, western Java Sea, and Sunda Strait. Salinity-normalized TAlk (NTAlk) in the surface water ranged 2,297-2,348 μmol kg −1 , very close to typical values observed in the tropical ocean. In the Karimata Strait, the Kapuas River plume was observed, featuring low salinity, DIC, and TAlk. In the western Java Sea, where waters were well mixed, we observed relatively homogeneous distributions of salinity, DIC, and TAlk. In the Sunda Strait, waters intruding from the Java Sea occupied the upper layer, and below was the Indian Ocean water with lower values of salinity, DIC, and TAlk. In its deep portion, depth profiles of normalized DIC and NTAlk were very similar to those observed in the Indian Ocean. Physical processes and air-sea gas exchange exerted predominant controls on the carbonate system in the Karimata Strait and western Java Sea. While both processes play large roles in the Sunda Strait, a net DIC removal of 31 ± 23 μmol kg −1 in the surface mixed layer were revealed. The drawdown of DIC is consistent with an overall supersaturation of dissolved oxygen (102-107%), suggesting significant organic carbon production. In the subsurface-intermediate waters of the Sunda Strait mainly influenced by the advection of Indian Ocean water, a net DIC consumption of 54 ± 45 μmol kg −1 was distinct, likely stimulated by the nutrients supplied from the Indian Ocean. Plain Language SummaryResearch on the carbonate system in the tropical regime of the Indonesian Seas is minimal, which hampers our understanding to its essential role in interbasin exchanges of material and energy via the Indonesian throughflow. Here we present a unique data set to examine the dynamics of the carbonate system in the western Indonesian Seas. Based on DIC and TAlk relationships, we show that water mass mixing in the western Indonesian Seas during the southeast monsoon is dominated by zonal wind-mixed waters from the plume of the Kapuas River, the Java Sea and South China Sea mixed water, and the subsurface Indian Ocean water. These processes resulted in homogenous distributions of physical properties and carbonate system parameters. However, biologically mediated DIC consumption occurred in the surface mixed layer of the Sunda Strait, which led to an increase in dissolved oxygen saturation, the saturation state of aragonite (Ω arag ), and pH. Overall, our region was a source of atmospheric CO 2 as previously reported, although the controlling processes may vary with respect to time at both seasonal and interannual timescales.

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Oksigen merupakan gas penting dalam perairan laut dan berperan dalam proses biogeokimia laut. Sumber oksigen berasal dari difusi dari udara melalui proses turbelensi dan hasil fotosintesis. Penelitian ini bertujuan untuk mengkaji distribusi dan pengaruh Indonesian Throughflow (ITF) terhadap konsentrasi oksigen terlarut di Selat Lombok. Sebanyak 11 stasiun (3 di utara; 6 di tengah; 2 di selatan) dianalisis kandungan oksigen terlarutnya dengan menggunakan metode modifikasi winkler. Hasil analisis menunjukan bahwa kandungan oksigen di bagian utara berkisar 2,48-7,15 mg/l, tengah 2,32-6,58 mg/l dan selatan 2,35-6,71 mg/l. Berdasarkan nilai apparent oxygen utilization (-2,70–5,64 mg/l) dan normal atmospheric equilibrium concentration (3,84-7,96 mg/l), mencerminkan kandungan oksigen yang semakin berkurang pada lapisan permukaan. AOU dan NAEC secara implisit berubah terhadap kedalaman dimana konsentrasinya akan semakin tinggi  dengan bertambahnya kedalaman. Hasil pengukuran suhu dan salinitas menunjukan bahwa Selat Lombok mempunyai suhu dan salinitas masing-masing berkisar antara 4,74-30,080C dan 33,48-34,78 psu. Analisis TS-diagram menunjukan terdapat dua massa air yang membawa kandungan oksigen di Selat Lombok yaitu Northern Subtropical Lower Water (NSLW) (salinitas=34,53-34,58 psu, suhu=13,57-15,06 0C; sigma-t (s t)=25,40-25,80)) dan Northern Pacific Intermediate Water  (NPIW) (salinitas=34,48-34,54 psu; suhu=6,30-7,90 0C; sigma-t (s t)=26,70-27,20). NSLW ditemukan pada kedalaman 100-180 (utara), 100-550 m (tengah) dan 190-220 m (selatan), sedangkan NPIW tidak terlihat dengan menggunakan pendekatan oksigen terlarut dan hanya bisa dilihat dengan pendekatan suhu dan salinitas.

<p>In this study, the concentrations of three kinds of heavy metals, namely Pb, Zn, and Cu from 3 species of mangrove that grow in Muara Angke were measured and analyzed. Our result showed that substrate of mangrove ecosystem in Muara Angke was dominated by clay (30.5% - 62.4%), silt (21.7% -35.6%), and sand (2% -39.5%). The heavy metals accumulation in roots is higher than in sediment, water and leaves with concentration of Zn as the highest. Bioconcentration Factor (BCF; content ratio of heavy metal concentrations in roots or leaves and sediment) and Translocation Factor (TF; ratio of heavy metal concentrations in leaves and roots) of non-essential heavy metals (Pb) is higher in leaves than in roots, but for essential heavy metals (Zn and Cu), the BCF and TF was higher in roots than in leaves. TF values for heavy metals Pb, Cu, and Zn were 0.98-2.59, 0.17-0.51, and 0.52-0.86, respectively. The values of root BCF of those three heavy metals were 0.71-3.17, 0.27-0.74, and 0.95-1.53, while the values of leaf BCF were 1.84-3.45, 0.07-0.34, and 0.72-1.19, respectively. Furthermore, by calculating the phytoremediation (FTD), i.e. the difference between BCF and TF, it is obtained that Sonneratia caseolaris and Avicennia marina can be used in phytoremidiation, with leaves and roots FTD of 1.93 and 2.09, respectively for Sonneratia caseolaris and 1.93 and 1.98 for Avicennia marina.</p><p>Keywords: heavy metals, mangroves, phytoremidiation, Muara Angke, bioconcentration factor, translocation factor</p>