Distribution and sources of particulate organic matter in a mesoscale eddy dipole in the Mozambique Channel (south-western Indian Ocean): Insight from C and N stable isotopes

AbstractThe Mozambique Channel trough (MCT) is a cyclonic region prominent in austral summer in the central and southern Mozambique Channel. It first becomes evident in December with a peak in strength in February when the Mozambique Channel is warmest and the Mascarene high (MH) is located farthest southeast in the Indian Ocean basin. The strength and the timing of the mean MCT are linked to that of the cross-equatorial northeasterly monsoon in the tropical western Indian Ocean, which curves as northwesterlies toward northern Madagascar. The interannual variability in the MCT is associated with moist convection over the Mozambique Channel and is modulated by the location of the warm sea surface temperatures in the south Indian Ocean. Variability of the MCT shows a strong relationship with the equatorial westerlies north of Madagascar and the latitudinal extension of the MH. Summers with strong MCT activity are characterized by a prominent cyclonic circulation over the Mozambique Channel, extending to the midlatitudes. These are favorable for the development of tropical–extratropical cloud bands over the southwestern Indian Ocean and trigger an increase in rainfall over the ocean but a decrease over the southern African mainland. Most years with a weak MCT are associated with strong positive south Indian Ocean subtropical dipole events, during which the subcontinent tends to receive more rainfall whereas Madagascar and northern Mozambique are anomalously dry.

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Patterns and controls of nitrogen stable isotopes of particulate organic matter in subtropical lakes

Annales de Limnologie - International Journal of Limnology ◽

10.1051/limn/2010005 ◽

2010 ◽

Vol 46 (1) ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Binhe Gu ◽

Claire L. Schelske

Keyword(s):

Stable Isotopes ◽

Organic Matter ◽

Particulate Organic Matter ◽

Nitrogen Stable Isotopes ◽

Subtropical Lakes

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Evaluation of sustainability of mixed food crop fields by monitoring particulate organic matter (POM) status and nutrient concentrations

Soil Research ◽

10.1071/sr07219 ◽

2008 ◽

Vol 46 (5) ◽

pp. 464 ◽

Cited By ~ 2

Author(s):

Lydie-Stella Koutika ◽

Martin Yemefack ◽

Daniel Folefoc

Keyword(s):

Organic Matter ◽

Particulate Organic Matter ◽

Exchange Capacity ◽

Nutrient Concentrations ◽

Food Crop ◽

Crop Fields ◽

Mixed Crop ◽

Crop Field ◽

C And N ◽

Sub Saharan

Particulate organic matter (POM) status is a useful indicator to assess labile soil organic matter (SOM) and to evaluate soil fertility under different agricultural systems, mainly in low-input agriculture as practiced in most of the sub-Saharan region of Africa. Total POM (53–4000 µm), different sized POM fraction characteristics (mass, C and N contents), and nutrient concentrations of soils were evaluated under 2 mixed food crop field types: a preceding forest fallow (forest) and a preceding fallow dominated by Chromolaena odorata (King & Robinson) (Chromolaena spp.) in the 0–0.10 m horizon of Rhodic Kandiudult, Typic Kandiudult, and Typic Kandiudox soils. The mass and C and N contents of total POM were higher in the Typic Kandiudox than in the Typic Kandiudult, while the Rhodic Kandiudult was intermediate. The pH was lower in the Typic Kandiudox (4.67). Forest had higher pH, Ca2+ and Mg2+ concentrations, and effective cation exchange capacity, while Chromolaena had higher C content in medium (2000–250 µm) and fine (250–53 µm) POM fractions and higher N content in coarse POM (4000–2000 µm). Considering nutrient concentrations, forest appears to be more suitable for a mixed-crop field-crop system than Chromolaena; however, the opposite was found when considering POM status.

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