Knowledge Resource Center for Ecological Environment in Arid Area
| Nutrient load from peatlands with different land-use option | |
| Pahkakangas;S. (Saila) | |
| 出版年 | 2016 |
| 学位授予单位 | University of Oulu |
| 英文摘要 | Abstract Peatlands drainage is known to increase nutrient leaching into downstream water systems and thus to deteriorate the status of natural water bodies. Drainage changes peatlands from nutrient and water accumulating systems to nutrient releasing catchment areas. This transformation happens due to lowering water table and changed runoff conditions. Deeper water table accelerates decomposing process and may expose nutrient rich peat layers during low discharge seasons, which can show up as elevated nutrient loads. Drainage may increase discharge rate trough peaks or as total discharge, which further can increase load by eroding nutrients from soil and by flushing the nutrients already present in ditch down to natural waters. There are few regional studies related to water impacts of drained peatlands with different land-use option. Load formation can be dependent on site-specific land management. The aim of this study was to analyse and compare water impacts of peatlands in agriculture, silviculture and peat extraction in relation to natural leaching from pristine mire. The studied sites are located in Northern Finland in Pelso (Vaala). To compare the studied sites, the nutrient (SS, DOC, Ptot, soluble PO4 and Ntot) and metal (Fe, Al, Mn) loads together with descriptive parameters (pH, EC, colour) were quantified with regular water samplings, continuous water level loggers and discharge measurements. Observation period was April-October. The effects of different land management on soil horizon and load formation were studied by analysing physical and chemical properties in each site. Based on the obtained results the nutrient load was higher from the drained areas compared to the pristine mire. The cultivated peatland had the highest daily loads of SS, Ptot, PO4, Fe and Al. Daily loads of Ntot, DOC and Mn were the highest in the peatland forest. From the drained sites, the peat extraction had the smallest loads. Loads from the pristine mire were the smallest. Determined soil characteristics reflected the implemented land management actions. High loads from the peatland forest, which have not been under silviculture actions, underlined the strong nutrifying impact of drainage itself. Observed loads were concentrated on high discharge season in August (high precipitation) and spring (snowmelt), which can be utilized in water protection work. The high nutrient load in the drained sites was originated from: a) increased discharge rates, b) altered hydrological and geochemical conditions and c) site-specific actions. In future, the effects if climate change on nutrient load could be studied with winter follow-up. Tiivistelmä Turvemaiden kuivatuksen on yleisesti havaittu lisäävään ravinnekuormitusta alapuolisiin vesistöihin ja siten heikentävän vesistöjen tilaa. Luonnollisessa tilassa oleva turvemaa toimii ravinne- ja vesivarastona. Kuivatuksen myötä veden pinta laskee, mikä nopeuttaa turpeen hajoamisprosessia ja lisää ravinteiden liukoisuutta. Aleneva vedenpinta saattaa paljastaa ravinnerikkaita, syvempiä turvekerroksia ja johtaa kuormituksen lisääntymiseen pienen virtaaman aikaan. Virtaama turvemailta saattaa lisääntyä joko kasvavien virtaamahuippujen tai lisääntyvän kokonaisvirtaaman myötä. Lisääntynyt virtaama voi kasvattaa kuormaa huuhtomalla ravinteita ojaverkostoon turvepinnasta tai huuhtomalla ojaverkossa jo olevan ravinnekuorman alapuolisiin vesistöihin. Alueellisten tutkimusten määrä eri maankäyttömuotojen vaikutuksesta kuormituksen syntyyn kuivatuilla turvemailla on vielä pieni. Kuormituksen syntyyn voivat vaikuttaa maankäyttömuodosta riippuvat toimenpiteet. Tämän tutkimuksen tarkoitus on analysoida ja vertailla maatalouden, metsätalouden ja turvetuotannon vesistövaikutuksia turvemailla suhteessa kuormitukseen luonnontilaiselta suolta. Tutkimusalueet sijaitsevat Pohjois-Suomessa Pelson kylässä (Vaala). Ravinne- (kiintoaine, DOC, Ptot, liukoiset PO4 ja Ntot) sekä metallikuormat (Fe, Al, Mn) eri maankäyttömuodoilta m |
| 英文关键词 | Environmental Engineering |
| 语种 | 其他 |
| URL | http://urn.fi/URN:NBN:fi:oulu-201601141009 |
| 来源机构 | University of Oulu |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/250083 |
| 推荐引用方式 GB/T 7714 | Pahkakangas;S. . Nutrient load from peatlands with different land-use option[D]. University of Oulu,2016. |
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