Increasing and Decreasing Nitrogen and Phosphorus Trends in Runoff from Drained Peatland Forests—Is There a Legacy Effect of Drainage or Not?     

Mika Nieminen  Sakari Sarkkola  Seppo Hellsten  Hannu Marttila  Sirpa Piirainen  Tapani Sallantaus  Ahti Lepistö 《Water, air, and soil pollution》2018,229(8):286

A recent study on nitrogen (N) and phosphorus (P) exports from drained peatland forests reported increasing concentrations over long time since their initial drainage. Concurrently, some other studies have suggested decreasing trends from drained peatland forests, particularly for P. To evaluate these contradictory findings, we re-analyzed past data and reviewed the literature related to temporal N and P concentration trends in runoff from drained peatland forests. Review of literature indicated that decreasing trends are found particularly in sites where initial P concentrations are high (>?50 μg P l^?1), plausibly because of relatively recent fertilization and drainage operations. Decreasing N trends have been found in sites where ditch cleaning temporarily decreased concentrations. Increasing N trends have occurred in sites, where initial concentrations have been low, close to the levels found in pristine peatlands. Complementing past published data with additional data from sites with no recent forestry operations indicated that N concentrations correlated positively with drainage age (years since initial drainage), percentage of drained peatlands in the catchment (drainage proportion), and southern location of the study site. P concentrations correlated most strongly with drainage age. Our study indicated that four factors, in particular, need to be considered when interpreting nutrient concentration trends in runoff from drained peatlands: 1) management history, 2) drainage age, 3) drainage proportion, and 4) site location. Our results supported earlier conclusions in that the estimates which ignore the legacy effect of drainage remarkably underestimate the true impact of forestry on water courses in intensively drained regions.  相似文献   

Brook Water Quality and Background Leaching from Unmanaged Forested Catchments in Finland     

Mattsson  Tuija  Finér  Leena  Kortelainen  Pirkko  Sallantaus  Tapani 《Water, air, and soil pollution》2003,147(1-4):275-298

The water chemistry of 21 outlet brooks in undisturbed, forested catchments (0.074–38 km²) in Finland was monitored during three years (1997–1999) in order to estimate the background levels and leaching of total organic carbon (TOC), iron, nitrogen and phosphorus, and examine the relationships between catchment characteristics and brook water quality in pristine forested areas. The studied catchments are located throughout Finland except the northernmost parts of the country. The concentrations of TOC were relatively high, on average 20 mg L^-1. Annual leaching of TOC ranged from 3000 to 10 000 kg km^-2. The average total nitrogen concentration and annual leaching were 430 μg L^-1 and 140 kg km^-2, respectively. The average total phosphorus concentration and annual leaching were 15 μg L^-1 and 5.4 kg km^-2, respectively. On a national level temperature and discharge conditions were the most important variables for predicting total phosphorus, total nitrogen and TOC concentrations. Both total nitrogen and total phosphorus concentrationsdisplayed positive correlation with temperature, and thus the concentrations were higher in the south than in the north. Nitrogen was mainly organic and showed strong correlation with TOC. On the catchment level, both TOC and total nitrogen concentrations and export had a strongpositive correlation with the abundance of Norway spruce (Piceaabies Karsten) and a strong negative correlation with the abundance of Scots pine (Pinus sylvestris L.). Nitrate concentrations and leaching were related to average site type. The more fertile the average site type was in the catchment, the higher the nitrate concentrations and export were.  相似文献