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G. 2007. Soil organic carbon content in northern Canada: A database of field measurements and its analysis. Can. J. Soil Sci. 87: 259-268. Arctic and sub-arctic soils contain a large amount of organic carbon in their topsoil horizons and in the upper layers of permafrost. There is concern that climate warming could release this soil organic carbon (SOC) to the atmosphere as greenhouse gases. However, information about the profile features and spatial distribution of SOC in northern ecosystems are far less than for other regions. In this study, we compiled all the available field measurements of SOC in northern Canada and developed a database. Including our recent measurements, the database contains 438 profiles with 1473 soil horizons. We analyzed the profile features and the regional patterns of SOC in northern Canada based on this database. The results show that the SOC content of subsurface soils is relatively high in northern regions because of the alternate freeze-thaw actions. In the top 100 cm of soils, 40% of the SOC is located in the 50-to 100-cm layer. The SOC content is lower in northern Arctic and in mountainous regions. The average upland SOC content in northern Canada is higher than in other world biomes (i.e., croplands, temperate forest, tropical savannas, and tropical forest) except temperate grasslands and boreal forest. On craint que le réchauffement du climat libère le carbone organique du sol (COS) dans l'atmosphère sous forme de gaz à effet de serre. Malheureusement, le profil et la répartition spatiale du COS sont beaucoup moins bien connus dans les écosystèmes nordiques que dans d'autres régions. Les auteurs ont colligé tous les relevés sur le COS disponibles effectués sur le terrain dans le nord du Canada pour en faire une base de données. En incluant leurs propres relevés, plus récents, les auteurs ont recensé 438 profils et 1 473 horizons. Ils ont analysé les paramètres de ces profils et les tendances régionales du COS dans le nord du Canada grâce à leur base de données. Les résultats indiquent que la concentration de COS sous la surface est relativement élevée dans le nord à cause de l'alternance du gel et du dégel. Dans les premiers 100 cm de sol, 40 % du COS se retrouve entre 50 et 100 cm de profondeur. La concentration de COS est plus faible dans les parties arctiques et montagneuses des régions nordiques. La concentration moyenne de COS sur les plateaux du nord du Canada s'avère plus élevée que dans d'autres biomes de la planète (par ex., terres agricoles, forêts tempérées, savanes tropicales et forêts tropicales) outre les prairies tempérées et la forêt boréale.

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An investigation was conducted to assess the impact of solid waste disposal on surrounding environment of Matuail landfill site of Dhaka city. Three different locations such as current dumping, abandoned and its surrounded agricultural areas of Matuail landfill were selected for soil and plant samples, leachate from active dumping and fish samples from treated leachate pond. The Cu, Zn and Pb concentrations were high in the dumping (360 µg g −1 Cu, 806 µg g −1 Zn and 382 µg g −1 Pb) and abandoned (199 µg g −1 Cu, 452 µg g −1 Zn and 519 µg g −1 Pb) areas that exceeded the permissible limits. The heavy metal concentrations in plant samples did not show any significant contamination except Cu, Zn and Pb that also exceeded the permissible limits. On the other side, the organic matter and nutrient concentrations such as N, P, K and S of both soil and plant samples are within desirable value in the studied area. The concentrations of DO, BOD, COD and TDS of the untreated leachate were found 1.34 mg L −1 , 96 mg L −1 , 1343 mg L −1 and 7120 mg L −1 , respectively that exceeded inland surface water standard but after treatment the concentrations of DO, BOD and TDS in the treated leachate pond were found within the permissible limit. The presence of heavy metal in leachate is not contaminated as it is below the toxic limit. The bioaccumulation of fish from treated pond is extremely high of Fe, Mn, Pb and Ni that exceeded the WHOs permissible limit.