Burial of large quantities of magnetite (Fe(II)Fe(III)2O4) in iron formations (IFs) likely contri... more Burial of large quantities of magnetite (Fe(II)Fe(III)2O4) in iron formations (IFs) likely contributed to the protracted oxidation of Earth’s surface during the Precambrian Eons. Magnetite can form through a diversity of biological and abiotic pathways and its preservation in IFs may thus be variably interpreted as the result of some combination of these processes. Such interpretations thus give rise to divergent pictures of the Precambrian Earth system and models for its evolution through time. New knowledge on the contribution of specific magnetite formation pathways is, therefore, needed to accurately tether our conceptual and numerical models to the geologic record. To constrain pathways of magnetite formation under ferruginous conditions, we conducted geochemical and multi-method microspectroscopic analyses on particles obtained from the water columns and sediments of ferruginous lakes Matano and Towuti, in Indonesia. We find that biologically reactive Fe(III) mineral phases ar...
ABSTRAK Danau Toba di Sumatera Utara adalah danau dengan tingkat pemanfaatan cukup tinggi baik di... more ABSTRAK Danau Toba di Sumatera Utara adalah danau dengan tingkat pemanfaatan cukup tinggi baik di wilayah daratan maupun di perairannya. Kegiatan-kegiatan tersebut akan memberikan pasokan hara yang dapat berpengaruh terhadap tingkat kesuburan perairan danau. Telah dilakukan penelitian ketersediaan komponen hara fosfor (TP; Total Phosphorus) dan nitrogen (TN; Total Nitrogen) di perairan Danau Toba dengan tujuan untuk evaluasi kondisi kesuburan dan tingkat ancaman degradasi perairan Danau Toba. Kegiatan penelitian dilaksanakan pada bulan April 2009 dan Oktober 2009 di 12 stasiun yang mewakili perairan, serta beberapa sungai utama yang menjadi inlet Danau Toba. Pasokan hara dari inlet-inlet Danau Toba, yaitu dari beberapa sungai yang terpilih menunjukkan adanya variasi yang tinggi. Distribusi horizontal TP dan TN bervariasi berdasarkan stasiun, sedangkan distribusi vertikal terlihat lebih tinggi kadarnya setelah kedalaman 100 m. Tingkat status trofik Danau Toba berdasarkan kadar TP berada antara oligotrofik hingga hipereutrofik, namun secara rata-rata berada pada kisaran mesotrofik. Sementara itu berdasarkan kadar TN, umumnya masih menunjukkan status oligotrofik. Meskipun ketersediaan ortofosfat di lapisan permukaan, yang merupakan hara utama pertumbuhan alga, relatif masih rendah, tetapi secara umum komponen nitrogen cenderung sebagai faktor pembatas pertumbuhan alga, dengan N:P <16 (massa). Pola distribusi vertikal TN dan TP cenderung meningkat dengan bertambahnya kedalaman. Kata Kunci: Danau Toba, Senyawaan Nitrogen (N) dan Fosfor (P), pasokan hara, distribusi hara ABSTRACT NITROGENOUS (N) AND PHOSPHORUS (P) NUTRIENTS AVAILABILITY IN LAKE TOBA, NORTH SUMATERA. Lake Toba is a high utilization lake, both in the mainland and in its waters. These activities will provide a supply of nutrients that can affect to the trophic state of waters. Has been studied availability of nutrients, especially total phosphorus (TP) and total nitrogen (TN), in order to evaluate trophic state condition and the threat of Lake Toba waters degradation. Research activities conducted at Lake Toba, North Sumatra Province on April 2009 and October 2009 at 12 stations, which represent the waters of lake, as well as some of the major rivers as Toba Lake inlet. Nutrient supply from the inflowing water, showed a high variation. Horizontal distribution of TP and TN varies according to the station, while the vertical distribution condition show that the higher levels were on 100 m depth. Base on TP level, water trophic status was between oligotrophic to hipereutrophic, but on average was in mesotrophic range. the trophic status was still oligotrophic. Vertical distribution pattern of TN and TP tended to increase with increasing depth. Even the availability of orthophosphate in the surface layer, which is the main nutrient of algae growth, is still relatively low, but in general, the nitrogenous tend to be a limiting factor for algae growth, with mass of N: P ratio <16.
Prosiding Seminar Nasional Limnologi VII-2014, 2014
Faktor Antrophogenik sudah tentu sangat mempengaruhi kualitas air di kolom badan air
Danau Maninj... more Faktor Antrophogenik sudah tentu sangat mempengaruhi kualitas air di kolom badan air Danau Maninjau. Salah satu yang sangat terpengaruh adalah konsentrasi Oksigen Terlarut (DO). Tetapi selain itu, tidak kalah pentingnya adalah peranan sedimen itu sendiri dalam mengkonsumsi DO di kolom badan air. Faktor internal inilah yang kami coba untuk diamati. Pengamatan untuk distribusi vertikal Oksigen terlarut dilakukan pada bulan Juli 2007, Desember 2011 dan September 2013, sedangkan pengambilan sampel sedimen di Sungai Kularian dilakukan pada bulan September 2013. Pengamatan dilakukan dengan mengukur Laju Sedimen Oksigen Demand (SOD) terhadap sedimen sungai yang berada di muara Sungai Kulariang dan sedimen Danau yang berada di bagian littoral danau dan yang berinteraksi langsung dengan sungai Kulariang. Penentuan SOD dilakukan dengan mengamati penurunan konsentrasi Oksigen Terlarut (DO) pada inkubasi sedimen di dalam botol BOD menggunakan DO meter ProODO YSI. Distribusi vertikal DO di danau dan sungai diukur dengan menggunakan WQC YSI Multiparameter. Hasil dari pengamatan ini adalah bahwa pola Oksiklin ditemukan berubah-rubah dari ketiga pengamatan yaitu berkisar pada kedalamaan 20-40m di Bulan Juli 2007, dan menaik sedikit ke permukaan pada Bulan desember 2011 (kedalaman 15m), dan pada kembali lebih dalam pada Bulan September 2013 (kedalaman 19,5m). Laju SOD pada sedimen Danau adalah 7.62 mg/m2.hari, sedangkan pada sedimen sungai adalah 3.242 mg/m 2.hari.
ABSTRAK Perairan Danau Toba dengan beragam fungsinya memerlukan pengelolaan yang terpadu. Klasifi... more ABSTRAK Perairan Danau Toba dengan beragam fungsinya memerlukan pengelolaan yang terpadu. Klasifikasi trofik suatu danau adalah perangkat penting sebagai dasar pengelolaan tersebut, selain memberikan gambaran tingkat intensitas pemanfaatannya. Penelitian mengenai penentuan status trofik di Danau Toba, Sumatera Utara telah dilaksanakan berdasarkan parameter-parameter Total Nitrogen (TN), Total Fosfor (TP), klorofil-a, dan kedalaman Secchi pada bulan April dan Oktober 2009. Pengamatan parameter-parameter dilakukan pada 12 stasiun yang mewakili, termasuk wilayah perairan bagian tengah danau. Danau Toba masih memiliki zona epilimnion yang aerobik sampai kedalaman 100 m. Klasifikasi status danau Toba terbentang dari oligo, meso, sampai eutrofik bila dilihat dari parameter hara TP, sedangkan bila dilihat dari parameter lainnya seperti kelimpahan klorofil-a maupun kedalaman Secchi, Danau Toba masih bersifat oligotrofik. Klasifikasi status berdasarkan indeks komposit Carlson (TSI), Danau Toba masih berstatus oligotrofik. Kata kunci : Danau Toba, status trofik, total nitrogen, total fosfor, klorofil a, kedalaman Sechi ABSTRACT TROPHIC CLASIFICATION OF LAKE TOBA, NORTH SUMATERA. Lake Toba with diverse functions requires integrated management. Trophic classification of a lake is important tool as a basis for management as well as information of it utilization intensity.A study on the determination of the trophic status of Lake Toba had been conducted based on the observation of Total Nitrogen (TN), Total Phosphorus (TP), chlorophyll-a, and Secchi depth. The investigation was done in April and October 2009 at 12 representative stations. Lake Toba still maintains the aerobic epilimnion zone through the depth of 100m. Classification of the trophic status of Lake Toba ranged from oligo, meso, to eutrophic based on the level of Total Phosphorus. Whereas, the classification of trophic status based on the abundance of chlorophyll-a and Secchi depth resulted in the trophic status of Lake Toba of oligotrophic. Classification of status trophic based on the Carlson's composite indice (Tropic State Index, TSI), showed that The Trophic Status of Lake Toba was still oligotrophic.
... Industrial water pollution, orginis, characteris-tics and treatment, Addison-Wesley Publishin... more ... Industrial water pollution, orginis, characteris-tics and treatment, Addison-Wesley Publishing Company, Massa-chusetts Oke, IA & AA. Akindahunsi. 2005. A statistical evaluation of method of determining BOD rate. J. Appl. Sci. Res. 1 (2): 223–227 Page 135. 288 Eko Harsono & ...
Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through wea... more Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest at the shallow site-a feature we attribute to the availability of labile organic matter (OM) and the higher abundance of electron acceptors due to oxic bottom water conditions. At the two other sites, OM degradation and reduction processes below the oxycline led to partial electron acceptor depletion. Genetic information preserved in the sediment as extracellular DNA (eDNA) provided information on aerobic and anaerobic heterotrophs related to Nitrospirae, Chloroflexi, and Thermoplasmatales. These taxa apparently played a significant role in the degradation of sinking OM. However, eDNA concentrations rapidly decreased with core depth. Despite very low sulfate concentrations, sulfate-reducing bacteria were present and viable in sediments at all three sites, as confirmed by measurement of potential sulfate reduction rates. Microbial community fingerprinting supported the presence of taxa related to Deltaproteobacteria and Firmicutes with demonstrated capacity for iron and sulfate reduction. Concomitantly, sequences of Ruminococcaceae, Clostridiales, and Methanomicrobiales indicated potential for fermentative hydrogen and methane production. Such first insights into ferruginous sediments showed that microbial populations perform successive metabolisms related to sulfur, iron, and methane. In theory, iron reduction could reoxidize reduced sulfur compounds and desorb OM from iron minerals to allow remineralization to methane. Overall, we found that biogeochemical processes in the sediments can be linked to redox differences in the bottom waters of the three sites, like oxidant concentrations and the supply of labile OM. At the scale of the lacustrine record, our geomicrobiological study should provide a means to link the extant subsurface biosphere to past environments.
Heterotrophic Proteo- and Actinobacteria were isolated from Lake Matano, Indonesia, a stratified,... more Heterotrophic Proteo- and Actinobacteria were isolated from Lake Matano, Indonesia, a stratified, ferruginous (iron-rich), ultra-oligotrophic lake with phosphate concentrations below 50 nM. Here, we describe the growth of eight strains of heterotrophic bacteria on a variety of soluble and insoluble sources of phosphorus. When transferred to medium without added phosphorus (P), the isolates grow slowly, their RNA content falls to as low as 1% of cellular dry weight, and 86-100% of the membrane lipids are replaced with amino- or glycolipids. Similar changes in lipid composition have been observed in marine photoautotrophs and soil heterotrophs, and similar flexibility in phosphorus sources has been demonstrated in marine and soil-dwelling heterotrophs. Our results demonstrate that heterotrophs isolated from this unusual environment alter their macromolecular composition, which allows the organisms to grow efficiently even in their extremely phosphorus-limited environment.
ABSTRACT As a nutrient required for growth, phosphorus regulates the activity of life in the ocea... more ABSTRACT As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry that is preserved as banded iron formations (BIFs) today. Here we show that Ca2+, Mg2+, and silica in seawater control phosphorus sorption onto iron oxides, influencing the record of seawater phosphorus preserved in BIFs. Using a model for seawater cation chemistry through time, combined with the phosphorus and silica content of BIFs, we estimate that seawater in the Archean and early Proterozoic Eons likely contained 0.04–0.13 μM phosphorus, on average. These phosphorus limiting conditions could have favored primary production through photoferrotrophy at the expense of oxygenic photosynthesis until upwelling waters shifted from phosphorus to iron limiting.
With a Secchi depth of <= 27m, tropical, ancient (1-4Ma) Lake Matano has surface waters as cle... more With a Secchi depth of <= 27m, tropical, ancient (1-4Ma) Lake Matano has surface waters as clear as many ultra-oligotrophic lakes such as Great Bear Lake (secchi depth 590m deep, one of the largest and deepest anoxic freshwater basins in the world. These sub-anoxic conditions have developed in response to thermal stratification that caused oxygen demand to exceed oxygen supply. Oxygen demand in lakes is generated principally by heterotrophic respiration and requires an organic carbon source. As autocthonous POC is remineralized in the epilimnion, the development of anoxia and the subsequent accumulation of the products of anaerobic respiration in the hypolimnion suggests that allocthonous organic matter drives hypolimnetic respiration. Preliminary measurements of DOC reveal concentrations several orders of magnitude higher than autochthonous POC in the epilimnion and lower concentrations in the hypolimnion. This concentration gradient induces a flux of DOC from the epilimnion to the hypolimnion. Such a DOC flux may completely sustain anaerobic respiration in Lake Matano. Nutrient (P,N) scavenging from the oxic/anoxic boundary has been cited as important for maintaining the limited phytoplankton crops in the epilimneon. As P fluxes to the epilimnion result from the reductive dissolution of particulate Fe-oxyhydroxides (during bacterial Fe respiration) allocthonous DOC may drive productivity in Lake Matano.
6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron ... more 6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron acceptors defined by free energy yield and availability. Methanogenesis by highly specialized Archea occurs once the availability of these electron acceptors is diminished beyond a thermodynamic threshold which renders the energy yield to low to sustain microbial respiration. In the deep waters of the persistently stratified and Fe-rich Lake Matano, Indonesia, authigenic organic matter is largely degraded through ...
Burial of large quantities of magnetite (Fe(II)Fe(III)2O4) in iron formations (IFs) likely contri... more Burial of large quantities of magnetite (Fe(II)Fe(III)2O4) in iron formations (IFs) likely contributed to the protracted oxidation of Earth’s surface during the Precambrian Eons. Magnetite can form through a diversity of biological and abiotic pathways and its preservation in IFs may thus be variably interpreted as the result of some combination of these processes. Such interpretations thus give rise to divergent pictures of the Precambrian Earth system and models for its evolution through time. New knowledge on the contribution of specific magnetite formation pathways is, therefore, needed to accurately tether our conceptual and numerical models to the geologic record. To constrain pathways of magnetite formation under ferruginous conditions, we conducted geochemical and multi-method microspectroscopic analyses on particles obtained from the water columns and sediments of ferruginous lakes Matano and Towuti, in Indonesia. We find that biologically reactive Fe(III) mineral phases ar...
ABSTRAK Danau Toba di Sumatera Utara adalah danau dengan tingkat pemanfaatan cukup tinggi baik di... more ABSTRAK Danau Toba di Sumatera Utara adalah danau dengan tingkat pemanfaatan cukup tinggi baik di wilayah daratan maupun di perairannya. Kegiatan-kegiatan tersebut akan memberikan pasokan hara yang dapat berpengaruh terhadap tingkat kesuburan perairan danau. Telah dilakukan penelitian ketersediaan komponen hara fosfor (TP; Total Phosphorus) dan nitrogen (TN; Total Nitrogen) di perairan Danau Toba dengan tujuan untuk evaluasi kondisi kesuburan dan tingkat ancaman degradasi perairan Danau Toba. Kegiatan penelitian dilaksanakan pada bulan April 2009 dan Oktober 2009 di 12 stasiun yang mewakili perairan, serta beberapa sungai utama yang menjadi inlet Danau Toba. Pasokan hara dari inlet-inlet Danau Toba, yaitu dari beberapa sungai yang terpilih menunjukkan adanya variasi yang tinggi. Distribusi horizontal TP dan TN bervariasi berdasarkan stasiun, sedangkan distribusi vertikal terlihat lebih tinggi kadarnya setelah kedalaman 100 m. Tingkat status trofik Danau Toba berdasarkan kadar TP berada antara oligotrofik hingga hipereutrofik, namun secara rata-rata berada pada kisaran mesotrofik. Sementara itu berdasarkan kadar TN, umumnya masih menunjukkan status oligotrofik. Meskipun ketersediaan ortofosfat di lapisan permukaan, yang merupakan hara utama pertumbuhan alga, relatif masih rendah, tetapi secara umum komponen nitrogen cenderung sebagai faktor pembatas pertumbuhan alga, dengan N:P <16 (massa). Pola distribusi vertikal TN dan TP cenderung meningkat dengan bertambahnya kedalaman. Kata Kunci: Danau Toba, Senyawaan Nitrogen (N) dan Fosfor (P), pasokan hara, distribusi hara ABSTRACT NITROGENOUS (N) AND PHOSPHORUS (P) NUTRIENTS AVAILABILITY IN LAKE TOBA, NORTH SUMATERA. Lake Toba is a high utilization lake, both in the mainland and in its waters. These activities will provide a supply of nutrients that can affect to the trophic state of waters. Has been studied availability of nutrients, especially total phosphorus (TP) and total nitrogen (TN), in order to evaluate trophic state condition and the threat of Lake Toba waters degradation. Research activities conducted at Lake Toba, North Sumatra Province on April 2009 and October 2009 at 12 stations, which represent the waters of lake, as well as some of the major rivers as Toba Lake inlet. Nutrient supply from the inflowing water, showed a high variation. Horizontal distribution of TP and TN varies according to the station, while the vertical distribution condition show that the higher levels were on 100 m depth. Base on TP level, water trophic status was between oligotrophic to hipereutrophic, but on average was in mesotrophic range. the trophic status was still oligotrophic. Vertical distribution pattern of TN and TP tended to increase with increasing depth. Even the availability of orthophosphate in the surface layer, which is the main nutrient of algae growth, is still relatively low, but in general, the nitrogenous tend to be a limiting factor for algae growth, with mass of N: P ratio <16.
Prosiding Seminar Nasional Limnologi VII-2014, 2014
Faktor Antrophogenik sudah tentu sangat mempengaruhi kualitas air di kolom badan air
Danau Maninj... more Faktor Antrophogenik sudah tentu sangat mempengaruhi kualitas air di kolom badan air Danau Maninjau. Salah satu yang sangat terpengaruh adalah konsentrasi Oksigen Terlarut (DO). Tetapi selain itu, tidak kalah pentingnya adalah peranan sedimen itu sendiri dalam mengkonsumsi DO di kolom badan air. Faktor internal inilah yang kami coba untuk diamati. Pengamatan untuk distribusi vertikal Oksigen terlarut dilakukan pada bulan Juli 2007, Desember 2011 dan September 2013, sedangkan pengambilan sampel sedimen di Sungai Kularian dilakukan pada bulan September 2013. Pengamatan dilakukan dengan mengukur Laju Sedimen Oksigen Demand (SOD) terhadap sedimen sungai yang berada di muara Sungai Kulariang dan sedimen Danau yang berada di bagian littoral danau dan yang berinteraksi langsung dengan sungai Kulariang. Penentuan SOD dilakukan dengan mengamati penurunan konsentrasi Oksigen Terlarut (DO) pada inkubasi sedimen di dalam botol BOD menggunakan DO meter ProODO YSI. Distribusi vertikal DO di danau dan sungai diukur dengan menggunakan WQC YSI Multiparameter. Hasil dari pengamatan ini adalah bahwa pola Oksiklin ditemukan berubah-rubah dari ketiga pengamatan yaitu berkisar pada kedalamaan 20-40m di Bulan Juli 2007, dan menaik sedikit ke permukaan pada Bulan desember 2011 (kedalaman 15m), dan pada kembali lebih dalam pada Bulan September 2013 (kedalaman 19,5m). Laju SOD pada sedimen Danau adalah 7.62 mg/m2.hari, sedangkan pada sedimen sungai adalah 3.242 mg/m 2.hari.
ABSTRAK Perairan Danau Toba dengan beragam fungsinya memerlukan pengelolaan yang terpadu. Klasifi... more ABSTRAK Perairan Danau Toba dengan beragam fungsinya memerlukan pengelolaan yang terpadu. Klasifikasi trofik suatu danau adalah perangkat penting sebagai dasar pengelolaan tersebut, selain memberikan gambaran tingkat intensitas pemanfaatannya. Penelitian mengenai penentuan status trofik di Danau Toba, Sumatera Utara telah dilaksanakan berdasarkan parameter-parameter Total Nitrogen (TN), Total Fosfor (TP), klorofil-a, dan kedalaman Secchi pada bulan April dan Oktober 2009. Pengamatan parameter-parameter dilakukan pada 12 stasiun yang mewakili, termasuk wilayah perairan bagian tengah danau. Danau Toba masih memiliki zona epilimnion yang aerobik sampai kedalaman 100 m. Klasifikasi status danau Toba terbentang dari oligo, meso, sampai eutrofik bila dilihat dari parameter hara TP, sedangkan bila dilihat dari parameter lainnya seperti kelimpahan klorofil-a maupun kedalaman Secchi, Danau Toba masih bersifat oligotrofik. Klasifikasi status berdasarkan indeks komposit Carlson (TSI), Danau Toba masih berstatus oligotrofik. Kata kunci : Danau Toba, status trofik, total nitrogen, total fosfor, klorofil a, kedalaman Sechi ABSTRACT TROPHIC CLASIFICATION OF LAKE TOBA, NORTH SUMATERA. Lake Toba with diverse functions requires integrated management. Trophic classification of a lake is important tool as a basis for management as well as information of it utilization intensity.A study on the determination of the trophic status of Lake Toba had been conducted based on the observation of Total Nitrogen (TN), Total Phosphorus (TP), chlorophyll-a, and Secchi depth. The investigation was done in April and October 2009 at 12 representative stations. Lake Toba still maintains the aerobic epilimnion zone through the depth of 100m. Classification of the trophic status of Lake Toba ranged from oligo, meso, to eutrophic based on the level of Total Phosphorus. Whereas, the classification of trophic status based on the abundance of chlorophyll-a and Secchi depth resulted in the trophic status of Lake Toba of oligotrophic. Classification of status trophic based on the Carlson's composite indice (Tropic State Index, TSI), showed that The Trophic Status of Lake Toba was still oligotrophic.
... Industrial water pollution, orginis, characteris-tics and treatment, Addison-Wesley Publishin... more ... Industrial water pollution, orginis, characteris-tics and treatment, Addison-Wesley Publishing Company, Massa-chusetts Oke, IA & AA. Akindahunsi. 2005. A statistical evaluation of method of determining BOD rate. J. Appl. Sci. Res. 1 (2): 223–227 Page 135. 288 Eko Harsono & ...
Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through wea... more Lake Towuti is a tectonic basin, surrounded by ultramafic rocks. Lateritic soils form through weathering and deliver abundant iron (oxy)hydroxides but very little sulfate to the lake and its sediment. To characterize the sediment biogeochemistry, we collected cores at three sites with increasing water depth and decreasing bottom water oxygen concentrations. Microbial cell densities were highest at the shallow site-a feature we attribute to the availability of labile organic matter (OM) and the higher abundance of electron acceptors due to oxic bottom water conditions. At the two other sites, OM degradation and reduction processes below the oxycline led to partial electron acceptor depletion. Genetic information preserved in the sediment as extracellular DNA (eDNA) provided information on aerobic and anaerobic heterotrophs related to Nitrospirae, Chloroflexi, and Thermoplasmatales. These taxa apparently played a significant role in the degradation of sinking OM. However, eDNA concentrations rapidly decreased with core depth. Despite very low sulfate concentrations, sulfate-reducing bacteria were present and viable in sediments at all three sites, as confirmed by measurement of potential sulfate reduction rates. Microbial community fingerprinting supported the presence of taxa related to Deltaproteobacteria and Firmicutes with demonstrated capacity for iron and sulfate reduction. Concomitantly, sequences of Ruminococcaceae, Clostridiales, and Methanomicrobiales indicated potential for fermentative hydrogen and methane production. Such first insights into ferruginous sediments showed that microbial populations perform successive metabolisms related to sulfur, iron, and methane. In theory, iron reduction could reoxidize reduced sulfur compounds and desorb OM from iron minerals to allow remineralization to methane. Overall, we found that biogeochemical processes in the sediments can be linked to redox differences in the bottom waters of the three sites, like oxidant concentrations and the supply of labile OM. At the scale of the lacustrine record, our geomicrobiological study should provide a means to link the extant subsurface biosphere to past environments.
Heterotrophic Proteo- and Actinobacteria were isolated from Lake Matano, Indonesia, a stratified,... more Heterotrophic Proteo- and Actinobacteria were isolated from Lake Matano, Indonesia, a stratified, ferruginous (iron-rich), ultra-oligotrophic lake with phosphate concentrations below 50 nM. Here, we describe the growth of eight strains of heterotrophic bacteria on a variety of soluble and insoluble sources of phosphorus. When transferred to medium without added phosphorus (P), the isolates grow slowly, their RNA content falls to as low as 1% of cellular dry weight, and 86-100% of the membrane lipids are replaced with amino- or glycolipids. Similar changes in lipid composition have been observed in marine photoautotrophs and soil heterotrophs, and similar flexibility in phosphorus sources has been demonstrated in marine and soil-dwelling heterotrophs. Our results demonstrate that heterotrophs isolated from this unusual environment alter their macromolecular composition, which allows the organisms to grow efficiently even in their extremely phosphorus-limited environment.
ABSTRACT As a nutrient required for growth, phosphorus regulates the activity of life in the ocea... more ABSTRACT As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry that is preserved as banded iron formations (BIFs) today. Here we show that Ca2+, Mg2+, and silica in seawater control phosphorus sorption onto iron oxides, influencing the record of seawater phosphorus preserved in BIFs. Using a model for seawater cation chemistry through time, combined with the phosphorus and silica content of BIFs, we estimate that seawater in the Archean and early Proterozoic Eons likely contained 0.04–0.13 μM phosphorus, on average. These phosphorus limiting conditions could have favored primary production through photoferrotrophy at the expense of oxygenic photosynthesis until upwelling waters shifted from phosphorus to iron limiting.
With a Secchi depth of <= 27m, tropical, ancient (1-4Ma) Lake Matano has surface waters as cle... more With a Secchi depth of <= 27m, tropical, ancient (1-4Ma) Lake Matano has surface waters as clear as many ultra-oligotrophic lakes such as Great Bear Lake (secchi depth 590m deep, one of the largest and deepest anoxic freshwater basins in the world. These sub-anoxic conditions have developed in response to thermal stratification that caused oxygen demand to exceed oxygen supply. Oxygen demand in lakes is generated principally by heterotrophic respiration and requires an organic carbon source. As autocthonous POC is remineralized in the epilimnion, the development of anoxia and the subsequent accumulation of the products of anaerobic respiration in the hypolimnion suggests that allocthonous organic matter drives hypolimnetic respiration. Preliminary measurements of DOC reveal concentrations several orders of magnitude higher than autochthonous POC in the epilimnion and lower concentrations in the hypolimnion. This concentration gradient induces a flux of DOC from the epilimnion to the hypolimnion. Such a DOC flux may completely sustain anaerobic respiration in Lake Matano. Nutrient (P,N) scavenging from the oxic/anoxic boundary has been cited as important for maintaining the limited phytoplankton crops in the epilimneon. As P fluxes to the epilimnion result from the reductive dissolution of particulate Fe-oxyhydroxides (during bacterial Fe respiration) allocthonous DOC may drive productivity in Lake Matano.
6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron ... more 6.1 Abstract Organic carbon is oxidized by microorganisms that use a series of terminal electron acceptors defined by free energy yield and availability. Methanogenesis by highly specialized Archea occurs once the availability of these electron acceptors is diminished beyond a thermodynamic threshold which renders the energy yield to low to sustain microbial respiration. In the deep waters of the persistently stratified and Fe-rich Lake Matano, Indonesia, authigenic organic matter is largely degraded through ...
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Danau Maninjau. Salah satu yang sangat terpengaruh adalah konsentrasi Oksigen Terlarut (DO).
Tetapi selain itu, tidak kalah pentingnya adalah peranan sedimen itu sendiri dalam mengkonsumsi
DO di kolom badan air. Faktor internal inilah yang kami coba untuk diamati. Pengamatan untuk
distribusi vertikal Oksigen terlarut dilakukan pada bulan Juli 2007, Desember 2011 dan September
2013, sedangkan pengambilan sampel sedimen di Sungai Kularian dilakukan pada bulan September
2013. Pengamatan dilakukan dengan mengukur Laju Sedimen Oksigen Demand (SOD) terhadap
sedimen sungai yang berada di muara Sungai Kulariang dan sedimen Danau yang berada di bagian
littoral danau dan yang berinteraksi langsung dengan sungai Kulariang. Penentuan SOD dilakukan
dengan mengamati penurunan konsentrasi Oksigen Terlarut (DO) pada inkubasi sedimen di dalam
botol BOD menggunakan DO meter ProODO YSI. Distribusi vertikal DO di danau dan sungai diukur
dengan menggunakan WQC YSI Multiparameter. Hasil dari pengamatan ini adalah bahwa pola
Oksiklin ditemukan berubah-rubah dari ketiga pengamatan yaitu berkisar pada kedalamaan 20-40m di
Bulan Juli 2007, dan menaik sedikit ke permukaan pada Bulan desember 2011 (kedalaman 15m), dan
pada kembali lebih dalam pada Bulan September 2013 (kedalaman 19,5m). Laju SOD pada sedimen
Danau adalah 7.62 mg/m2.hari, sedangkan pada sedimen sungai adalah 3.242 mg/m 2.hari.
Danau Maninjau. Salah satu yang sangat terpengaruh adalah konsentrasi Oksigen Terlarut (DO).
Tetapi selain itu, tidak kalah pentingnya adalah peranan sedimen itu sendiri dalam mengkonsumsi
DO di kolom badan air. Faktor internal inilah yang kami coba untuk diamati. Pengamatan untuk
distribusi vertikal Oksigen terlarut dilakukan pada bulan Juli 2007, Desember 2011 dan September
2013, sedangkan pengambilan sampel sedimen di Sungai Kularian dilakukan pada bulan September
2013. Pengamatan dilakukan dengan mengukur Laju Sedimen Oksigen Demand (SOD) terhadap
sedimen sungai yang berada di muara Sungai Kulariang dan sedimen Danau yang berada di bagian
littoral danau dan yang berinteraksi langsung dengan sungai Kulariang. Penentuan SOD dilakukan
dengan mengamati penurunan konsentrasi Oksigen Terlarut (DO) pada inkubasi sedimen di dalam
botol BOD menggunakan DO meter ProODO YSI. Distribusi vertikal DO di danau dan sungai diukur
dengan menggunakan WQC YSI Multiparameter. Hasil dari pengamatan ini adalah bahwa pola
Oksiklin ditemukan berubah-rubah dari ketiga pengamatan yaitu berkisar pada kedalamaan 20-40m di
Bulan Juli 2007, dan menaik sedikit ke permukaan pada Bulan desember 2011 (kedalaman 15m), dan
pada kembali lebih dalam pada Bulan September 2013 (kedalaman 19,5m). Laju SOD pada sedimen
Danau adalah 7.62 mg/m2.hari, sedangkan pada sedimen sungai adalah 3.242 mg/m 2.hari.