Nitrogen stocks and flows in an acid sulfate soil
ENVIRONMENTAL MONITORING AND ASSESSMENT
Authors: Yli-Halla, Markku; Virtanen, Seija; Regina, Kristiina; Osterholm, Peter; Ehnvall, Betty; Uusi-Kamppa, Jaana
Besides causing acidification, acid sulfate (AS) soils contain large nitrogen (N) stocks and are a potential source of N loading to waters and nitrous oxide (N2O) emissions. We quantified the stocks and flows of N, including crop yields, N leaching, and N2O emissions, in a cultivated AS soil in western Finland. We also investigated whether controlled drainage (CD) and sub-irrigation (CDI) to keep the sulfidic horizons inundated can alleviate N losses. Total N stock at 0-100 cm (19.5 Mg ha(-1)) was smaller than at 100-200 cm (26.6 Mg ha(-1)), and the mineral N stock was largest below 170 cm. Annual N leaching (31-91 kg N ha(-1)) plus N in harvested grain (74-122 kg N ha(-1)) was 148% (range 118-189%) of N applied in fertilizers (90-125 kg N ha(-1)) in 2011-2017, suggesting substantial N supply from soil reserves. Annual emissions of N2O measured during 2 years were 8-28 kg N ha(-1). The most probable reasons for high N2O emission rates in AS soils are concomitant large mineral N pools with fluctuating redox conditions and low pH in the oxidized subsoil, all favoring formation of N2O in nitrification and denitrification. Although the groundwater level was higher in CD and CDI than in conventional drainage, N load and crop offtake did not differ between the drainage methods, but there were differences in emissions. Nitrogen flows to the atmosphere and drainage water were clearly larger than those in non-AS mineral soils indicating that AS soils are potential hotspots of environmental impacts.
Aligning Hearing Aid and Cochlear Implant Improves Hearing Outcome in Bimodal Cochlear Implant Users
OTOLOGY & NEUROTOLOGY
Authors: Holtmann, Laura Christine; Janosi, Anna; Bagus, Heike; Scholz, Tim; Lang, Stephan; Arweiler-Harbeck, Diana; Hans, Stefan
Objective: Patients with unilateral deafness and residual hearing on the contralateral ear can benefit from a cochlear implant (CI) on one side and a hearing aid (HA) on the other. However, hearing improvement among these patients is heterogenous. Interindividual differences in bimodal benefit may be caused by a mismatch of CI and HA. The aim of this study was to clinically apply a HA fitting strategy and to evaluate hearing outcome with and without a dedicated bimodal fitting formula. Study Design: Prospective non-randomized study. Setting: Tertiary referral center. Patients: Twelve patients using a CI processor and a conventional HA were enrolled. Before and after the new HA had been adjusted to the patient and linked to the CI, pure-tone audiometry and localization tests were performed. Speech perception was determined in quiet and noise. Tests were repeated after 6 and 12 weeks. To evaluate the subjective listening comfort two questionnaires (Oldenburg Inventory and HISQUI(19)) were assessed. Intervention: Therapeutic. Results Main outcome measure: Word recognition in quiet, sentence recognition in noise. Speech perception in noise improved significantly: directed suppression of noise helped to segregate the target speech signal from a mixture of sounds or competing speakers. Evaluation of the questionnaires revealed a positive subjective hearing experience compared with patients' initial settings of the devices. Conclusion: By linking CI and HA hearing and speech perception can be improved. However, good counselling at the outset is essential to obtain enhanced outcome.