In the 12 years since Dudgeon et al.(2006) reviewed major pressures on freshwater
ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and …

Increasing salt production and use is shifting the natural balances of salt ions across Earth
systems, causing interrelated effects across biophysical systems collectively known as …

Soils play an essential role in the global cycling of carbon and understanding the
stabilisation mechanisms behind the preservation of soil organic carbon (SOC) pools is of …

The physiological relationship between abiotic stress in plants and polyamines was reported
more than 40 years ago. Ever since there has been a debate as to whether increased …

Acidic deposition was first identified by RA Smith in England in the 19th century (Smith
1872). Acidic deposition emerged as an ecological issue in the late 1960s and early 1970s …

Anthropogenic nitrogen (N) enrichment of ecosystems, mainly from fuel combustion and
fertilizer application, alters biogeochemical cycling of ecosystems in a way that leads to …

Atmospheric particulate matter (PM) is a heterogeneous material. Though regulated as un-
speciated mass, it exerts most effects on vegetation and ecosystems by virtue of the mass …

Human-caused environmental changes are creating regional combinations of
environmental conditions that, within the next 50 to 100 years, may fall outside the envelope …

At the Earth's surface, calcium (Ca) is a critical element at a variety of scales: it is soluble in
natural waters, a biological nutrient, and a major constituent of the dominant mineral sink for …

SummaryI. INTRODUCTION–A HYPOTHESIS 374II. EFFECTS OF CALCIUM ON
PHYSIOLOGICAL PROCESSES 3761. The chemical uniqueness of calcium 376 (a) …