The supply of nitrogen commonly limits plant production in boreal forests and also affects
species composition and ecosystem functions other than plant growth. These interrelations …

Human activities have already modified the chemical composition of the natural atmosphere
even in very remote regions of the world. The study of chemical parameters stored in solid …

Nitrogen is a key element controlling the species composition, diversity, dynamics, and
functioning of many terrestrial, freshwater, and marine ecosystems. Many of the original …

For the past 3.8 billion years, the geochemistry of the Earth's surface-its atmosphere, waters
and exposed crust-has been determined by the presence of biota. Photosynthetic organisms …

In the absence of human activities, biotic fixation is the primary source of reactive N,
providing about 90–130 Tg N yr− 1 (Tg= 1012 g) on the continents. Human activities have …

The Greenland Ice Sheet Project 2 glaciochemical series (sodium, potassium, ammonium,
calcium, magnesium, sulfate, nitrate, and chloride) provides a unique view of the chemistry …

A compilation of paleoclimate records from lake sediments, trees, glaciers, and marine
sediments provides a view of circum-Arctic environmental variability over the last 400 years …

Acid-vulnerable areas are more numerous and widespread than believed 7 years ago.
Lakes and streams in acid-vulnerable areas of northeastern North America have suffered …

Concern about the potential climatic influence of changing atmospheric aerosol loadings
was first voiced in the 1960s, when Mccormick and Ludwig (1967) suggested that increasing …

1.2 Carbon Dioxide 1 2 1 The Cycle of Carbon in Nature 12 11 The role of the atmosphere
12 12 The role of the ocean 12 13 The role of terrestrial vegetation and soils 1 2 2 …