Wintertime Greenhouse Gas Fluxes in Hemiboreal Drained Peatlands

Funding Information: Funding: This study was supported by the Estonian Research Council (IUT2-16 and PRG352); the EU through the European Regional Development Fund (Centre of Excellence EcolChange, Estonia) and by the Estonian State Forest Management Centre (projects LLOOM13056 “Carbon and nitrogen cycling in forests with altered water regime “, 2013–2016 and LLTOM17250 “Water level restoration in cut-away peatlands: development of integrated monitoring methods and monitoring”, 2017–2023).Peer reviewedPublisher PD

Haljaskatuste temperatuuri- ja veerežiim ning nõrgvee kvaliteet

In this PhD dissertation, three general benefits of planted roofs in Estonian climatic conditions are investigated. The temperature regime is analyzed on an existing LWA-based green roof (100 mm) and on a sod roof (150 mm) to determine the differences from typical planted roofs. In addition, 1x1.5 m roof plots were constructed and studied to see how non-insulated planted roofs acted in a cooler period. Three rainfall events and snow cover melting were measured. The runoff water quality of LWA-based green roofs and sod roofs was analyzed and compared with precipitation and conventional roofs to find at which scale water quality may appear. The measurement period was from June 2004 to April 2009. The investigations showed that planted roofs are sufficiently effective in Estonian climatic conditions. The green roof can provide a base roof with effective protection against the influence of intensive solar radiation. In summer and winter, temperatures under both the green roof and the sod roof showed a similar temperature run. In autumn and spring, the sod roof’s soil layer showed higher temperatures and lower amplitude than the green roof’s substrate layer. The studied green roof effectively retained light rain but cannot fully retain heavy rainstorm. Runoff water results showed that vegetated roofs influenced water quality to a considerable degree. While the temperature regime of the planted roofs has been investigated sufficiently, further investigations in fields of water quantity and quality are required to draw definite conclusions regarding the capability of planted roofs to retain water and improve water quality in Estonian climatic conditions. Käesoleva doktoritöö eesmärk on analüüsida katusehaljastuse kolme põhilist kasutegurit Eesti kliimas. Temperatuurirežiimi uuriti kergmuru- (100 mm) ja mätaskatusel (150 mm) eesmärgiga hinnata kahe tüüpilise haljaskatuse temperatuuri kõikumist alandavat mõju. Samuti teostati temperatuuriuuringud alt soojustamata 1x1.5 m suurustel katseplatvormidel. Veerežiimi jälgiti kolme vihmasaju ning lume sulaperioodi ajal eesmärgiga hinnata rohekatuste vee äravoolu hulka vähendavat ja algust edasilükkavat võimet. Veekvaliteedi analüüse võeti kergmurukatustelt ning mätaskatustelt, võrreldes neid sademete ning võrdluskatuste tulemustega eesmärgiga leida, millises skaalas võib vee kvaliteet varieeruda. Uuringud toimusid juunist 2004 kuni aprillini 2009. Teostatud uurimused näitasid, et haljaskatused on Eesti kliimatingimustes piisavalt efektiivsed. Tulemustest saab järeldada, et võrreldes tavakatustega on nii kergmuru- kui mätaskatus võimelised vähendama temperatuurikõikumiste mõju aluskatusele. Kahe tüübi tulemused olid suvel ja talvel sarnased, sügisel ja kevadel oli mätaskatuse pinnase temperatuur kõrgem ja väiksema amplituudiga. Vee kinnipidamisvõime tulemused näitasid, et haljaskatus suudab kinni pidada nõrga vihma, kuid paduvihma substraat kinni hoida ei suuda. Mõlemad haljaskatuste tüübid omavad sõltuvalt teguritest märkimisväärset mõju nõrgvee kvaliteedile. Kindlamate järelduste tegemiseks haljaskatuste efektiivsuse kohta Eesti tingimustes on vajalik teostada põhjalikumaid uuringuid igas valdkonnas, eeskätt aga nõrgvee kvantiteedi ning kvaliteedi osas

Effects of the nitrification inhibitor nitrapyrin and tillage practice on yield-scaled nitrous oxide emission from a maize field in Iran

Nitrification inhibitors can effectively decrease nitrification rates and nitrous oxide (N2O) emission while increasing crop yield under certain conditions. However, there is no information available on the effects of nitrification inhibitors and tillage practices on N2O emissions from maize cropping in Iran. To study how tillage practices and nitrapyrin (a nitrification inhibitor) affect N2O emission, a split factorial experiment using a completely randomized block design with three replications was carried out in Northeast Iran, which has a cold semiarid climate. Two main plots were created with conventional tillage and minimum tillage levels, and two nitrogen (N) fertilizer (urea) management systems (with and without nitrapyrin application) were created as subplots. Tillage level did not have any significant effect on soil ammonium (NH4+) and nitrate (NO3–) concentrations, cumulative amount and yield-scaled N2O emission, and aboveground biomass of maize, whereas nitrapyrin application showed significant effect. Nitrapyrin application significantly reduced the cumulative amount of N2O emission by 41% and 32% in conventional tillage and minimum tillage practices, respectively. A reduction in soil NO3– concentration by nitrapyrin was also observed. The average yield-scaled N2O emission was 13.6 g N2O-N kg–1 N uptake in both tillage systems without nitrapyrin application and was significantly reduced to 7.9 and 8.2 g N2O-N kg–1 N uptake upon the application of nitrapyrin in minimum tillage and conventional tillage practices, respectively. Additionally, nitrapyrin application increased maize biomass yield by 4% and 13% in the minimum tillage and conventional tillage systems, respectively. Our results indicate that nitrapyrin has a potential role in reducing N2O emission from agricultural systems where urea fertilizers are broadcasted, which is common in Iran due to the practice of traditional farming.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro en Investigación en Contaminación Ambiental (CICA

Nitrogen-rich organic soils under warm well-drained conditions are global nitrous oxide emission hotspots

International audienceNitrous oxide (N 2 O) is a powerful greenhouse gas and the main driver of stratospheric ozone depletion. Since soils are the largest source of N 2 O, predicting soil response to changes in climate or land use is central to understanding and managing N 2 O. Here we find that N 2 O flux can be predicted by models incorporating soil nitrate concentration (NO 3 −), water content and temperature using a global field survey of N 2 O emissions and potential driving factors across a wide range of organic soils. N 2 O emissions increase with NO 3 − and follow a bell-shaped distribution with water content. Combining the two functions explains 72% of N 2 O emission from all organic soils. Above 5 mg NO 3 −-N kg −1 , either draining wet soils or irrigating well-drained soils increases N 2 O emission by orders of magnitude. As soil temperature together with NO 3 − explains 69% of N 2 O emission, tropical wetlands should be a priority for N 2 O management