A new mechanism for calcium loss in forest-floor soils

Article Abstract:

The reactive form of Aluminum (Al) is mobilized from the mineral soil to the forest-floor soil due to acid deposition. This reactive Al reduces the availability of Calcium (Ca) present in the forest-floor soil to the plants. The Ca uptake by plants decrease as a consequence. The decrease of exchangeable Ca in the upper soil horizon is not accompanied by a change in exchangeable H or soil pH. Dissolution of mineral Al or decomplexation of organic Al are not responsible for the loss of Ca since these does not occur from acid deposition.

Aluminum (Metal), Forest soils, Soils, Calcium, Calcium (Chemical element), Soil chemistry, Neutralization (Chemistry)

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Large increases in flood magnitude in response to modest changes in climate

Article Abstract:

The magnitude of flooding can be affected by small changes in climate, as shown by the past 7,000 years of the Upper Mississippi River tributaries. Analysis of the geological record shows that larger floods occurred as climate cooled, such as at times preceding the Little Ice Age. Flood sizes increased from standard 50-year floods to 500-year floods or greater, while temperature only changed one to two degrees centigrade on average and rainfall increased from 10% to 20% annually.

Climatic changes, Climate change, Floods

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Nitrate flux in the Mississippi River

Article Abstract:

Issues are presented concerning the development of a model which can be used to investigate the eutrophication of the Gulf of Mexico by the Mississippi River. The influence of nitrogen-containing fertilizers on eutrophication is discussed.

Models, Eutrophication, Gulf of Mexico, Nitrogen fertilizers

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