2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/22/2019 | 10:00 AM - 10:15 AM | TRAJECTORIES OF RECOVERY FROM ACID RAIN OVER 31 YEARS (AMBIENT) AND 2 YEARS (EXPERIMENTAL) AT THE BEAR BROOK WATERSHED IN MAINE (BBWM), USA | 151 DEF
TRAJECTORIES OF RECOVERY FROM ACID RAIN OVER 31 YEARS (AMBIENT) AND 2 YEARS (EXPERIMENTAL) AT THE BEAR BROOK WATERSHED IN MAINE (BBWM), USA
BBWM is a paired forested watershed experiment. The untreated watershed (EB) experienced a relatively constant decline in SO4 and NO3 deposition during the study (1987-2018). Ca and Mg in EB runoff declined faster than (SO4+NO3), resulting in acidification (lower alkalinity and pH, higher Al+n) until 2005; alkalinity and pH then increased slowly as base cations reached a minimum about 2015 and started increasing. The WB watershed received bimonthly applications of (NH4)2SO4 from 1989 to 2016. Na and K in EB and WB runoff are dominated by atmospheric input and runoff of marine aerosols, and plant uptake and leaf senescence, respectively. WB runoff, almost immediately after treatment started, had higher SO4 and NO3, increased base cations, H+, and Al+n. Base cations increased until about 1995, and then declined to near pre-treatment values by 2016. SO4+NO3 remained elevated but declined slowly. Since 2016, NO3 dramatically declined to virtually the detection limit, while SO4 remains elevated. Retention of NO3 during treatment was ~80% and nearly 100% since 2015. Neither watershed has reached equilibrium. The recovery trajectory of WB chemistry is steeper than, and lags behind, that of EB.
- Monitoring
- Nitrogen
- Water Quality
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Presenters/Authors
Stephen Norton
(), University of Maine, Norton@maine.edu;
ASHA DISCLOSURE:
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Nonfinancial -
Ivan Fernandez
(), University of Maine, Ivanjf@Maine.edu;
ASHA DISCLOSURE:
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Nonfinancial -