In forests of the northeastern United States, sulfate and nitrate are the dominant dissolved forms of sulfur and nitrogen in precipitation. In winter, these acidic agents accumulate in the snowpack and are released to groundwater and streams over a short period of time during spring snowmelt.
This pulsed release of sulfate and nitrate in snowmelt can cause episodic acidification in poorly buffered soils, ultimately threatening the health of acid-sensitive biota.
There have been recent studies showing that biological cycling of sulfur and nitrogen persists in cold weather, despite below freezing air temperatures. Much of this activity occurs in soils, where an insulating snow layer keeps soil temperatures warm enough for a range of biological processes. Despite the growing awareness of winter’s role in sulfur and nitrogen cycling, many questions remain unanswered. In particular, there is much uncertainty about how sulfate and nitrate are retained or transformed in forest soils during cold weather.
In the November-December 2007 issue of the Soil Science Society of America Journal (SSSAJ), scientists from the U.S. Forest Service, SUNY-ESF, University of Calgary, and Cary Institute of Ecosystem Studies tracked the movement of sulfate and nitrate deposited in snow. A solution containing isotopically enriched sulfate and nitrate was sprayed on the surface of the snowpack during mid winter. The isotopic values of the labeled sulfate and nitrate were well above background levels and served as a tracer to follow the movement and transformation of these compounds in the ecosystem.
The researchers found that almost all of the labeled sulfate and nitrate deposited on the surface of the snow was recovered in snowmelt water, indicating that there were no significant transformations of sulfate and nitrate in the snowpack. In contrast, about half of the sulfate and nitrate was retained or transformed in the forest floor, suggesting that organic soils are a sink for these compounds during winter. For sulfate, the amount retained or transformed in the forest floor was nearly equal to the amount released, resulting in no significant net gains or losses. A significant amount of ammonium was produced in the forest floor indicating that N mineralization can be important, even when soil temperatures are near freezing. By contrast, net nitrification rates were very low during winter. Tracer results indicated that microbes did not immobilize snowpack nitrate and that other processes such as plant uptake, denitrification, and abiotic nitrate retention were probably more important factors affecting nitrate during snowmelt. More information on controls on nitrogen and sulfur cycling during winter is critical to our understanding of long-term trends and will help us predict how forest ecosystems will respond to future disturbances and global change processes.
The full article is available for no charge for 30 days following the date of this summary. View the abstract at: http://soil.scijournals.org/cgi/content/abstract/71/6/1934
Soil Science Society of America Journal, http://soil.scijournals.org, is a peer-reviewed international journal published six times a year by the Soil Science Society of America. Its contents focus on research relating to physics; chemistry; biology and biochemistry; fertility and plant nutrition; genesis, morphology, and classification; water management and conservation; forest, range, and wildland soils; nutrient management and soil and plant analysis; mineralogy; and wetland soils.
The Soil Science Society of America (SSSA) www.soils.org is an educational organization based in Madison, Wisconsin, which helps its 6,000+ members advance the disciplines and practices of soil science by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services.
Sara Uttech | EurekAlert!
Global threat to primates concerns us all
19.01.2017 | Deutsches Primatenzentrum GmbH - Leibniz-Institut für Primatenforschung
Reducing household waste with less energy
18.01.2017 | FIZ Karlsruhe – Leibniz-Institut für Informationsinfrastruktur GmbH
A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
24.01.2017 | Physics and Astronomy
24.01.2017 | Life Sciences
24.01.2017 | Health and Medicine