Effect of natural levels of Dissolved Organic Carbon (DOC) on methyl mercury formation and sediment-water partitioning

1991 ◽  
Vol 47 (5) ◽  
pp. 743-750 ◽  
Author(s):  
B. M. Miskimmin
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Methyl Mercury ◽  
Water Partitioning

Impact of wildfire and clear-cutting in the boreal forest on methyl mercury in zooplankton

1999 ◽  
Vol 56 (2) ◽  
pp. 339-345 ◽  
Author(s):  
Edenise Garcia ◽  
Richard Carignan
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Dissolved Oxygen ◽  
Boreal Forest ◽  
Methyl Mercury ◽  
Dry Weight ◽  
Zooplankton Biomass ◽  
Clear Cutting ◽  
Forest Logging ◽  
Reference Lakes

We compared the effects of forest logging and wildfire on methyl mercury (MeHg) concentrations in bulk zooplankton collected in 38 oligotrophic lakes located in the boreal forest. Mean MeHg concentrations were slightly but significantly higher (P < 0.01) in zooplankton collected in lakes with recently logged watersheds (135 ng·g dry weight-1) than in lakes with recently burned (97 ng·g dry weight-1) or undisturbed watersheds (112 ng·g dry weight-1). MeHg levels in zooplankton collected in burned and reference lakes were not significantly different. Multiple regression including all the lakes showed that four variables (dissolved organic carbon, pH, dissolved oxygen, and immature zooplankton biomass) explained 43% of the variability in MeHg levels in bulk zooplankton. Regressions calculated for each group of lakes explained less (reference lakes) or more of the variability in MeHg (logged and burned lakes) than the general model did. Dissolved organic carbon was the only variable common to all models, which indicates the importance of watershed processes in the transfer of humic matter bound Hg to lakes. However, variables related to methylation rate, such as pH, sulfate concentrations, and average dissolved oxygen in lake water, also explained part of the variation in MeHg concentrations in zooplankton.

CHARACTERISATION OF DISSOLVED ORGANIC CARBON (DOC) LEACHED FROM LEAVES IN WATER

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Markus Heryanto Langsa
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Total Organic Carbon ◽  
Gas Chromatography Mass Spectrometry ◽  
Pyrolysis Gas ◽  
Pyrolysis Gas Chromatography ◽  
Chromatography Mass Spectrometry ◽  
Pinus Radiate

<p>Penelitian ini bertujuan untuk menentukan senyawa organik khususnya organic karbon terlarut (DOC) dari dua spesies daun tumbuhan (<em>wandoo eucalyptus </em>and <em>pinus radiate, conifer</em>) yang larut dalam air selama periode 5 bulan leaching eksperimen. Kecepatan melarutnya senyawa organic ditentukan secara kuantitatif dan kualitatif menggunakan kombinasi dari beberapa teknik diantaranya Total Organic Carbon (TOC) analyser, Ultraviolet-Visible (UV-VIS) spektrokopi dan pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS).</p><p>Hasil analisis DOC dan UV menunjukkan peningkatan yang tajam dari kelarutan senyawa organic di awal periode pengamatan yang selanjutnya berkurang seiring dengan waktu secara eksponensial. Jumlah relatif senyawa organic yang terlarut tergantung pada luas permukaan, aktifitas mikrobiologi dan jenis sampel tumbuhan (segar atau kering) yang digunakan. Fluktuasi profil DOC dan UV<sub>254</sub> disebabkan oleh aktifitas mikrobiologi. Diperoleh bahwa daun kering lebih mudah terdegradasi menghasilkan senyawa organic dalam air dibandingkan dengan daun segar. Hasil pyrolysis secara umum menunjukkan bahwa senyawa hidrokarbon aromatic dan fenol (dan turunannya) lebih banyak ditemukan pada residue sampel setelah proses leaching kemungkinan karena adanya senyawa lignin atau aktifitas humifikasi mikrobiologi membuktikan bahwa senyawa-senyawa tersebut merupakan komponen penting dalam proses karakterisasi DOC.</p>

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