کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4426192 | 1309121 | 2008 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Rapid immobilisation and leaching of wet-deposited nitrate in upland organic soils Rapid immobilisation and leaching of wet-deposited nitrate in upland organic soils](/preview/png/4426192.png)
Nitrate (NO3−) is often observed in surface waters draining terrestrial ecosystems that remain strongly nitrogen (N) limited. It has been suggested that this occurs due to hydrological bypassing of soil or vegetation N retention, particularly during high flows. To test this hypothesis, artificial rain events were applied to 12 replicate soil blocks on a Welsh podzolic acid grassland hillslope, labelled with 15N-enriched NO3− and a conservative bromide (Br−) tracer. On average, 31% of tracer-labelled water was recovered within 4 h, mostly as mineral horizon lateral flow, indicating rapid vertical water transfer through the organic horizon via preferential flowpaths. However, on average only 6% of 15N-labelled NO3− was recovered. Around 80% of added NO3− was thus rapidly immobilised, probably by microbial communities present on the surfaces of preferential flowpaths. Transitory exceedance of microbial N-uptake capacity during periods of high water and N flux may therefore provide a mechanism for NO3− leaching.
Journal: Environmental Pollution - Volume 156, Issue 3, December 2008, Pages 636–643