CO<SUB>2</SUB> evasion along streams driven by groundwater inputs and geomorphic controls

International audienceHeadwaters are hotspots of carbon dioxide (CO2) evasion from rivers. While emerging evidence suggests that groundwater contributes disproportionately to CO2 in headwater streams, the processes of CO2 delivery to streams and subsequent evasion to the atmosphere remain largely unknown. Here we show the variability of CO2 input and evasion fluxes based on coupled measurements of dissolved CO2 along streams and in adjacent groundwater from two headwater catchments of the tropical and temperate zones. We find that the processes can be highly localized in both space and time. Spatially, they are significantly influenced by heterogeneities in the subsurface and stream landscape; temporally, they predominately occur during the transient activation of connected subsurface water flows. We highlight sharp increases and decreases in the stream CO2 flux, and suggest that current models fail to capture the true magnitude of CO2 evasion. The high spatial and temporal variability of CO2 input from groundwater and evasion to the atmosphere makes accurate assessment of CO2 evasion fluxes difficult, and will require a collaborative effort by catchment hydrologists and aquatic ecologists to fully understand the contribution of groundwater to stream CO2 emissions

Implementation of push notification using SignalR and WCF

Komunikacijo med strežniki in odjemalci lahko realiziramo na več načinov. Osnoven način je, da odjemalec povprašuje in strežnik odgovarja. V primeru, ko odjemalec ne ve, kdaj mu bo določena informacija na voljo, mora v intervalih spraševati strežnik. To je neučinkovito in boljša alternativa temu je, da strežnik obvešča odjemalce. Takemu načinu komunikacije pravimo potisno obveščanje. Implementacijo potisnega obveščanja smo izvedli s knjižnico SignalR in z ogrodjem WCF. Obe tehnologiji smo raziskali in ju primerjali. Za primerjavo tehnologij smo implementirali obveščanje o dogajanju v nadzoru različic kode. V našem primeru smo imeli dva tipa odjemalcev. En odjemalec je vmesnik za upravljanje z nadzorom različic kode Git. Ta obvešča strežnik o akcijah, ki se dogajajo nad kodo. Drugi tip odjemalca pa je namizna aplikacija in aplikacija za Windows Phone 8. Obe aplikaciji sprejemata obvestila o dogajanju v nadzoru različic kode, ki jim jih pošilja strežnik.Communication between servers and clients can be realised in several ways. A basic method is, when the client requests and the server responds. In case the client does not know, when the specific information will be available, it needs to ask the server in intervals. This is ineffective, and a better alternative is when the server informs the clients. Such communication is called server push. Server push was implemented with the SignalR library and with the WCF framework. Both technologies have been explored and compared. For comparison of technologies we implemented the notification of activity in revision control. In our case, we had two types of clients. The first client is an interface for managing the control of the Git revision control. It informs the server about actions, which take place over the code. The second client is a desktop application and an application for Windows Phone 8. Both applications receive notifications of activities in revision control