Reducing nitrogen control costs by within- and cross-county targeting.

The Total Maximum Daily Load (TMDL) program established by the United States Environmental Protection Agency (US EPA) to improve America's water quality is being applied to the Chesapeake Bay watershed to mitigate the "dead zone" problem. Agricultural activities are the major nonpoint source of nitrogen (N), contributing 44% of total N to the Bay. Best Management Practices (BMPs) are recognized as an effective way to mitigate N loss of agricultural activities. However, because of physical and economic heterogeneity in agricultural regions, targeting BMPs to areas that produce disproportionate nutrient losses has the potential to reduce the costs of achieving water quality goals. The purpose of this study is to examine the potential to reduce costs of meeting a regional water quality goal by targeting N load reductions within- and across-counties. Based on TMDL developed by the US EPA in 2010 for the Chesapeake Bay watershed, the N reduction goal is 35% for Pennsylvania by 2025. We examine the effects of targeting the required reductions within counties, across counties, and both within and across counties for the Susquehanna watershed. Using the uniform strategy to meet 35% N reduction as the baseline, results show that costs of achieving a regional 35% N reduction goal can be reduced by 13%, 31% and 36% with cross-county targeting, within-county targeting and within and across county targeting, respectively. Cost effectiveness of government subsidy programs for water quality improvement in agriculture can be increased by targeting them to areas with lower N abatement costs.

Meeting Water Quality Goals by Spatial Targeting of Best Management Practices under Climate Change.

Agricultural production is a major source of nonpoint source pollution contributing 44% of total nitrogen (N) discharged to the Chesapeake Bay. The United States Environmental Protection Agency (US EPA) established the Total Maximum Daily Load (TMDL) program to control this problem. For the Chesapeake Bay watershed, the TMDL program requires that nitrogen loadings be reduced by 25% by 2025. Climate change may affect the cost of achieving such reductions. Thus, it is necessary to develop cost-effective strategies to meet water quality goals under climate change. We investigate landscape targeting of best management practices (BMPs) based on topographic index (TI) to determine how targeting would affect costs of meeting N loading goals for Mahantango watershed, PA. We use the results from two climate models, CRCM and WRFG, and the mean of the ensemble of seven climate models (Ensemble Mean) to estimate expected climate changes and the Soil and Water Assessment Tool-Variable Source Area (SWAT-VSA) model to predict crop yields and N export. Costs of targeting and uniform placement of BMPs across the entire study area (423 ha) were compared under historical and future climate scenarios. Targeting BMP placement based on TI classes reduces costs for achieving water quality goals relative to uniform placement strategies under historical and future conditions. Compared with uniform placement, targeting methods reduce costs by 30, 34, and 27% under historical climate as estimated by the Ensemble Mean, CRCM and WRFG, respectively, and by 37, 43, and 33% under the corresponding estimates of future climate scenarios.

A structured 2-week follow-up visit in the cascade of care for TB increases case detection.

Delayed detection in TB due to structural and diagnostic shortcomings is pivotal for disease transmission, morbidity and mortality. We investigated whether an inclusive screening, followed by a structured clinical follow-up (FU) could improve case-finding.Patients were recruited from health centres in Bissau, Guinea-Bissau, and Gondar, Ethiopia. A routine FU was done at Week 2. If persisting symptoms were found, patients were investigated using chest X-ray (CXR) and Xpert® MTB/RIF, followed by a medical consultation. The main outcome were additional TB patients diagnosed by applying the FU strategy.Of 3,571 adults, 3,285 (95%) were examined at Week 2 FU, where 2,491 (72%) were asymptomatic. Screening patients presenting with cough >2 weeks alone contributed to the diagnosis of 93 patients (45% of all patients diagnosed here), whereas a TBscore >3 increased this by 18 (9%); adding a Week 2 FU yielded an additional 94 (46%) patients. Among the 794 (24%) with persisting symptoms, 25 were diagnosed using Xpert and 69 at clinical FU, which constituted 46% (94/205) of the total TB patients diagnosed.A Week 2 FU visit, which can be nested into routine healthcare, increased the diagnosis of TB patients by two-fold and avoids diagnostic gaps in the cascade-of-care..

Agricultural conservation practices can help mitigate the impact of climate change.

Agricultural conservation practices (CPs) are commonly implemented to reduce diffuse nutrient pollution. Climate change can complicate the development, implementation, and efficiency of agricultural CPs by altering hydrology, nutrient cycling, and erosion. This research quantifies the impact of climate change on hydrology, nutrient cycling, erosion, and the effectiveness of agricultural CP in the Susquehanna River Basin in the Chesapeake Bay Watershed, USA. We develop, calibrate, and test the Soil and Water Assessment Tool-Variable Source Area (SWAT-VSA) model and select four CPs; buffer strips, strip-cropping, no-till, and tile drainage, to test their effectiveness in reducing climate change impacts on water quality. We force the model with six downscaled global climate models (GCMs) for a historic period (1990-2014) and two future scenario periods (2041-2065 and 2075-2099) and quantify the impact of climate change on hydrology, nitrate-N (NO3-N), total N (TN), dissolved phosphorus (DP), total phosphorus (TP), and sediment export with and without CPs. We also test prioritizing CP installation on the 30% of agricultural lands that generate the most runoff (e.g., critical source areas-CSAs). Compared against the historical baseline and with no CPs, the ensemble model predictions indicate that climate change results in annual increases in flow (4.5±7.3%), surface runoff (3.5±6.1%), sediment export (28.5±18.2%) and TN export (9.5±5.1%), but decreases in NO3-N (12±12.8%), DP (14±11.5), and TP (2.5±7.4%) export. When agricultural CPs are simulated most do not appreciably change the water balance, however, tile drainage and strip-cropping decrease surface runoff, sediment export, and DP/TP, while buffer strips reduce N export. Installing CPs on CSAs results in nearly the same level of performance for most practices and most pollutants. These results suggest that climate change will influence the performance of agricultural CPs and that targeting agricultural CPs to CSAs can provide nearly the same level of water quality effects as more widespread adoption.

Impact of climate change and climate anomalies on hydrologic and biogeochemical processes in an agricultural catchment of the Chesapeake Bay watershed, USA.

Nutrient export from agricultural landscapes is a water quality concern and the cause of mitigation activities worldwide. Climate change impacts hydrology and nutrient cycling by changing soil moisture, stoichiometric nutrient ratios, and soil temperature, potentially complicating mitigation measures. This research quantifies the impact of climate change and climate anomalies on hydrology, nutrient cycling, and greenhouse gas emissions in an agricultural catchment of the Chesapeake Bay watershed. We force a calibrated model with seven downscaled and bias-corrected regional climate models and derived climate anomalies to assess their impact on hydrology and the export of nitrate (NO3-), phosphorus (P), and sediment, and emissions of nitrous oxide (N2O) and di-nitrogen (N2). Model-average (±standard deviation) results indicate that climate change, through an increase in precipitation and temperature, will result in substantial increases in winter/spring flow (10.6 ±â€¯12.3%), NO3- (17.3 ±â€¯6.4%), dissolved P (32.3 ±â€¯18.4%), total P (24.8 ±â€¯16.9%), and sediment (25.2 ±â€¯16.6%) export, and a slight increases in N2O (0.3 ±â€¯4.8%) and N2 (0.2 ±â€¯11.8%) emissions. Conversely, decreases in summer flow (-29.1 ±â€¯24.6%) and the export of dissolved P (-15.5 ±â€¯26.4%), total P (-16.3 ±â€¯20.7%), sediment (-20.7 ±â€¯18.3%), and NO3- (-29.1 ±â€¯27.8%) are driven by greater evapotranspiration from increasing summer temperatures. Decreases in N2O (-26.9 ±â€¯15.7%) and N2 (-36.6 ±â€¯22.9%) are predicted in the summer and driven by drier soils. While the changes in flow are related directly to changes in precipitation and temperature, the changes in nutrient and sediment export are, to some extent, driven by changes in agricultural management that climate change induces, such as earlier spring tillage and altered nutrient application timing and by alterations to nutrient cycling in the soil.