Task 4.1 Denitrification in rice paddies
- In the Ticino river basin, 8-10 agricultural wells tapping the shallow aquifer will be selected in areas with different irrigation regimes (permanent or intermittent flooding).
- The water table depth and hydrochemical parameters (major ions, nutrients, Fe and Mn contents) will be measured monthly during the rice cropping season, and every two months in winter.
- Dissolved gases (CH4, N2O, O2 and N2/Ar ratios) and stable isotopes of dissolved nitrates will be analyzed whenever a nitrate concentration change in groundwater will be detected. This will allow to quantify with these different analytical techniques the percent of nitrate removed, and assess by difference the amount of N2 and N2O escaped to the atmosphere.
Task 4.2 Denitrification in shallow groundwater from the lower plain
- The same investigation as the previous task 4.1 will be conducted in the Adda river basin.
- This will permit to quantify the percent of nitrate removed, and assess by difference the amount of N2 and N2O escaped to the atmosphere.
Task 4.3 Factors affecting P mobility
- Soil profiles located in areas displaying detectable amounts of dissolved phosphates in groundwater will be identified and retrieved form the ERSAF collection (Brenna et al., 2004; Sacchi et al., 2008).
- Mineralogical analyses will be conducted on these samples using X-ray diffractometry.
- Total P content and P speciation will be determined. This will allow to identify the mineralogical control on P retention, the environmental conditions and the processes by which it can be mobilized, transferred to groundwater and recycled to surface waters with consequences on their trophic status.