Allocating Nutrient Load Reduction across a Watershed: Implications of Different Principles

A watershed based model, the Soil and Water Assessment Tool (SWAT), along with transfer coefficients is used to assess alternative principles of allocating nutrient load reduction in the Raccoon River watershed in central Iowa. Four principles are examined for their cost-effectiveness and impacts on water quality: absolute equity, equity based on ability, critical area targeting, and geographic proximity. Based on SWAT simulation results, transfer coefficients are calculated for the effects of nitrogen application reduction. We find both critical area targeting and downstream focus (an example of geographic proximity) can be more expensive than equal allocation, a manifestation of absolute equity. Unless abatement costs are quite heterogeneous across the subwatersheds, the least-cost allocation (an application of the principle of equity based on ability) have a potential of cost savings of about 10% compared to equal allocation. We also find that the gap between nitrogen loading estimated from transfer coefficients and nitrogen loading predicted by SWAT simulation is small (in general less than 5%). This suggests that transfer coefficients can be a useful tool for watershed nutrient planning. Sensitivity analyses suggest that these results are robust with respect to different degrees of nitrogen reduction and how much other conservation practices are used.Environmental Economics and Policy,

Predicting pharmacy naloxone stocking and dispensing following a statewide standing order, Indiana 2016

BACKGROUND: While naloxone, the overdose reversal medication, has been available for decades, factors associated with its availability through pharmacies remain unclear. Studies suggest that policy and pharmacist beliefs may impact availability. Indiana passed a standing order law for naloxone in 2015 to increase access to naloxone. OBJECTIVE: To identify factors associated with community pharmacy naloxone stocking and dispensing following the enactment of a statewide naloxone standing order. METHODS: A 2016 cross-sectional census of Indiana community pharmacists was conducted following a naloxone standing order. Community, pharmacy, and pharmacist characteristics, and pharmacist attitudes about naloxone dispensing, access, and perceptions of the standing order were measured. Modified Poisson and binary logistic regression models attempted to predict naloxone stocking and dispensing, respectively. RESULTS: Over half (58.1%) of pharmacies stocked naloxone, yet 23.6% of pharmacists dispensed it. Most (72.5%) pharmacists believed the standing order would increase naloxone stocking, and 66.5% believed it would increase dispensing. Chain pharmacies were 3.2 times as likely to stock naloxone. Naloxone stocking was 1.6 times as likely in pharmacies with more than one full-time pharmacist. Pharmacies where pharmacists received naloxone continuing education in the past two years were 1.3 times as likely to stock naloxone. The attempted dispensing model yielded no improvement over the constant-only model. CONCLUSIONS: Pharmacies with larger capacity took advantage of the naloxone standing order. Predictors of pharmacist naloxone dispensing should continue to be explored to maximize naloxone access

Privatizing Ecosystem Services: Water Quality Effects from a Carbon Market

Resource /Energy Economics and Policy, Q25,

Optimal Placement of Conservation Practices Using Genetic Algorithm with SWAT

The effectiveness of conservation practices depends on their placement on the fields within the watershed. Cost-effective placement of these practices for maximum water quality benefits on each field requires comparing a very large number of possible land-use scenarios. To address this problem, we combine the tools of evolutionary algorithm with the Soil and Water Assessment Tool (SWAT) model and cost data to develop a trade-off frontier of least cost of achieving nutrient reductions and the corresponding locations of conservation practices. This approach was applied to the Raccoon River Watershed, which drains about 9,400 km2 of an intensive agriculture region in west-central Iowa. Applying genetic algorithm to the calibrated SWAT modeling setup produced multitudes of optimal solutions of achieving nutrient reductions in relation to the total cost of placing these practices. For example, a 30% reduction in nitrate (and a corresponding 53% reduction in phosphorus) at the watershed outlet can be achieved with a cost of $80 million per year. This solution frontier allows policymakers and stakeholders to explicitly see the trade-offs between cost and nutrient reductions

Climate Change Sensitivity Assessment on Upper Mississippi River Basin Streamflows Using SWAT

The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed on a monthly basis for 1968-87 and 1988-97, respectively; R2 and Nash-Sutcliffe simulation efficiency (E) values computed for the monthly comparisons were 0.74 and 0.65 for the calibration period and 0.81 and 0.75 for the validation period. The impacts of eight 20-year (1971- 90) scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO2 concentrations was predicted to result in an average annual flow increase of 35 percent. An average annual flow decrease of 15 percent was estimated for a constant temperature increase of 4°C. Essentially linear impacts were predicted among precipitation change scenarios of -20, -10, 10, and 20 percent, which resulted in average annual flow changes at Grafton, Illinois, of -51, -27, 28, and 58 percent, respectively. The final two scenarios accounted for variable monthly temperature and precipitation changes obtained from a previous climate projection with and without the effects of CO2 doubling. The resultant average annual flows were predicted to increase by 15 and 52 percent in response to these climatic changes. Overall, the results indicate that the UMRB hydrology is very sensitive to potential future climate changes and that these changes could stimulate increased periods of flooding or drought

Climate Change Sensitivity Assessment on Upper Mississippi River Basin Streamflows using SWAT

The Soil and Water Assessment Tool (SWAT) model was used to assess the effects of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed using monthly stream flows for 1968–1987 and 1988–1997, respectively. The R2 and Nash-Sutcliffe simulation efficiency values computed for the monthly comparisons were 0.74 and 0.69 for the calibration period and 0.82 and 0.81 for the validation period. The effects of nine 30-year (1968 to 1997) sensitivity runs and six climate change scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO2 to 660 ppmv (while holding other climate variables constant) resulted in a 36 percent increase in average annual streamflow while average annual flow changes of −49, −26, 28, and 58 percent were predicted for precipitation change scenarios of −20, −10, 10, and 20 percent, respectively. Mean annual streamflow changes of 51,10, 2, −6, 38, and 27 percent were predicted by SWAT in response to climate change projections generated from the CISRO-RegCM2, CCC, CCSR, CISRO-Mk2, GFDL, and HadCMS general circulation model scenarios. High seasonal variability was also predicted within individual climate change scenarios and large variability was indicated between scenarios within specific months. Overall, the climate change scenarios reveal a large degree of uncertainty in current climate change forecasts for the region. The results also indicate that the simulated UMRB hydrology is very sensitive to current forecasted future climate changes

Impact of highly basic solutions on sorption of Cs+ to subsurface sediments from the Hanford site, USA

The effect of caustic NaNO3 solutions on the sorption of 137Cs to a Hanford site micaceous subsurface sediment was investigated as a function of base exposure time (up to 168 d), temperature (10°C or 50°C), and NaOH concentration (0.1 mol/L to 3 mol/L). At 10°C and 0.1 M NaOH, the slow evolution of [Al]aq was in stark contrast to the rapid increase and subsequent loss of [Al]aq observed at 50°C (regardless of base concentration). Exposure to 0.1 M NaOH at 10°C for up to 168 d exhibited little if any measurable effect on sediment mineralogy, Cs+ sorption, or Cs+ selectivity; sorption was well described with a two-site ion exchange model modified to include enthalpy effects. At 50°C, dissolution of phyllosilicate minerals increased with [OH]. A zeolite (tetranatrolite; Na2Al2Si3O10·2H2O) precipitated in 0.1 M NaOH after about 7 days, while an unnamed mineral phase (Na14Al12Si13O51·6H2O) precipitated after 4 and 2 days of exposure to 1 M and 3 M NaOH solutions, respectively. Short-term (16 h) Cs+ sorption isotherms (10−9–10−2 mol/L) were measured on sediment after exposure to 0.1 M NaOH for 56, 112, and 168 days at 50°C. There was a trend toward slightly lower conditional equilibrium exchange constants (∆log NaCsKc ~ 0.25) over the entire range of surface coverage, and a slight loss of high affinity sites (15%) after 168 days of pretreatment with 0.1 M base solution. Cs+ sorption to sediment over longer times was also measured at 50°C in the presence of NaOH (0.1 M, 1 M, and 3MNaOH) at Cs+ concentrations selected to probe a range of adsorption densities. Model simulations of Cs+ sorption to the sediment in the presence of 0.1 M NaOH for 112 days slightly under-predicted sorption at the lower Cs+ adsorption densities. At the higher adsorption densities, model simulations under-predicted sorption by 57%. This under-prediction was surmised to be the result of tetranatrolite precipitation, and subsequent slow Na → Cs exchange. At higher OH concentrations, Cs+ sorption in the presence of base for 112 days was unexpectedly equal to, or greater than that expected for pristine sediment. The precipitation of secondary phases, coupled with the fairly unique mica distribution and quantity across all size-fractions in the Hanford sediment, appears to mitigate the impact of base dissolution on Cs+ sorption

Impact of highly basic solutions on sorption of Cs+ to subsurface sediments from the Hanford site, USA

The effect of caustic NaNO3 solutions on the sorption of 137Cs to a Hanford site micaceous subsurface sediment was investigated as a function of base exposure time (up to 168 d), temperature (10°C or 50°C), and NaOH concentration (0.1 mol/L to 3 mol/L). At 10°C and 0.1 M NaOH, the slow evolution of [Al]aq was in stark contrast to the rapid increase and subsequent loss of [Al]aq observed at 50°C (regardless of base concentration). Exposure to 0.1 M NaOH at 10°C for up to 168 d exhibited little if any measurable effect on sediment mineralogy, Cs+ sorption, or Cs+ selectivity; sorption was well described with a two-site ion exchange model modified to include enthalpy effects. At 50°C, dissolution of phyllosilicate minerals increased with [OH]. A zeolite (tetranatrolite; Na2Al2Si3O10·2H2O) precipitated in 0.1 M NaOH after about 7 days, while an unnamed mineral phase (Na14Al12Si13O51·6H2O) precipitated after 4 and 2 days of exposure to 1 M and 3 M NaOH solutions, respectively. Short-term (16 h) Cs+ sorption isotherms (10−9–10−2 mol/L) were measured on sediment after exposure to 0.1 M NaOH for 56, 112, and 168 days at 50°C. There was a trend toward slightly lower conditional equilibrium exchange constants (∆log NaCsKc ~ 0.25) over the entire range of surface coverage, and a slight loss of high affinity sites (15%) after 168 days of pretreatment with 0.1 M base solution. Cs+ sorption to sediment over longer times was also measured at 50°C in the presence of NaOH (0.1 M, 1 M, and 3MNaOH) at Cs+ concentrations selected to probe a range of adsorption densities. Model simulations of Cs+ sorption to the sediment in the presence of 0.1 M NaOH for 112 days slightly under-predicted sorption at the lower Cs+ adsorption densities. At the higher adsorption densities, model simulations under-predicted sorption by 57%. This under-prediction was surmised to be the result of tetranatrolite precipitation, and subsequent slow Na → Cs exchange. At higher OH concentrations, Cs+ sorption in the presence of base for 112 days was unexpectedly equal to, or greater than that expected for pristine sediment. The precipitation of secondary phases, coupled with the fairly unique mica distribution and quantity across all size-fractions in the Hanford sediment, appears to mitigate the impact of base dissolution on Cs+ sorption