Exploring the adoption of water quality trading as an alternative stormwater regulatory compliance strategy for land development projects: A case study for Roanoke, Virginia.

Urban stormwater runoff is a significant source of nutrient pollution that is very costly to treat. Water quality trading (WQT) is a market-based strategy that can be used to lower the costs associated with meeting stormwater quality regulations. While many WQT programs have experienced low participation, Virginia's program has seen high participation due to the inclusion of land developers and other regulated stormwater dischargers. However, the extent to which WQT is used as a compliance option by regulated stormwater dischargers is not well understood, particularly when compared with the adoption of traditional compliance options. To address this knowledge gap, we collated a novel dataset comprising site characteristics and stormwater compliance methods for all development projects in the City of Roanoke, Virginia from December 2015 to March 2022. We analyzed this dataset to characterize the adoption of nutrient offset credits and other compliance methods being used, including best management practices (BMPs) and improved land covers associated with reduced nutrient export. Results show that credits are the preferred compliance option in Roanoke and were used as the only treatment compliance method for 59% of projects with treatment requirements. Projects using credits corresponded with a lower median disturbed area (1.36 acres) and lower median nutrient load reduction requirement (0.69 pounds of total phosphorus per year) compared with other compliance methods. Furthermore, we found that 58% of the projects that used credits achieved stormwater quantity compliance using methods other than implementing stormwater control devices. By mapping buyers and sellers of credits, we found that all credit sellers are downstream of the development projects. We discuss how this downstream trading could be a cause for concern, as part of a larger discussion of the advantages of tracking stormwater compliance methods, drawing on Roanoke as a case study.

Assessing and improving the outcomes of nonpoint source water quality trading policies in urban areas: A case study in Virginia.

Nonpoint source (NPS) water quality trading (WQT) is a market-based approach to improving water quality. Past work has shown that these programs could increase localized pollutant loadings, in part by exporting water quality controls from urban to rural areas. Virginia's NPS WQT program has enabled thousands of transactions and may provide a model for other programs, but its impacts on urban water quality have not been thoroughly assessed. We quantify the impact of NPS WQT purchases in Virginia on water quality and hydrology in an urban catchment. We go on to assess outcomes of a policy alternative where buyers and sellers are collocated in the urban catchment. Simulation results show that NPS WQT increased total phosphorus (TP) loading by an average of 0.8 lbs TP/year for each 1.0 offsite credits purchased in the analyzed catchment. The TP loading increased in years with greater rainfall, such that TP loads were increased by up to 1.2 lbs TP/year for each offsite credit purchased. These loading increases may or may not be acceptable, depending on the cumulative number of purchases within an urban catchment and existing local water quality issues. In our policy alternative with buyers and sellers collocated in the catchment, we found that the TP increase from development was completely offset at the catchment scale, with a decrease of 4.3 lbs TP/year for each 1.0 credits purchased. This suggests that credits awarded for urban mitigation practices are undervalued compared with water quality requirements for credit purchasers. This undervaluation is a result of the Virginia trading program using one approach to compute the credit value for buyers and a different approach to compute the credit value for sellers. We demonstrate how using a single model to determine both buyer and seller credit values in urban areas could provide greater transparency and mitigate the risk of urban pollution hot spots. This work demonstrates the importance of consistency in the scale of pollutant load calculations between buyers and sellers for NPS WQT, and contributes novel insight into the implications of WQT for urban NPS pollution.

Nonpoint Source Water Quality Trading outcomes: Landscape-scale patterns and integration with watershed management priorities.

Nonpoint source (NPS) water quality trading (WQT) has been lauded as a way to reduce water pollution while mitigating costs, but NPS WQT programs often do not account for cumulative landscape-scale impacts to hydrological and ecological processes. In this work, we parameterize the landscape-scale patterns of an emerging NPS WQT market in Virginia (n = 606 transactions) and describe potential tradeoffs and synergies. We also examine program outcomes in the context of Virginia's spatially-explicit conservation and restoration priorities, and discuss ways in which NPS WQT integrates or fails to integrate with these state-level watershed management goals. These spatial and policy analyses demonstrate novel ways to evaluate NPS WQT programs. Our results reveal how NPS WQT has influenced Virginia land management patterns in practice. Specifically, we show that this program has encouraged the transfer of water quality Best Management Practices (BMPs) from urban to rural areas. Impact sites are often far from mitigation sites, at an average of 164.6 km apart measured along the stream network and most often migrated outside the 8-digit Hydrologic Unit Code watershed boundaries. We also find opportunity for improved integration with the state-level management priorities, including that an estimated 22% of the NPS WQT mitigation site area works against state priorities (for example by converting prime farmland to forest), 9% supports state priorities, and 69% neither negates nor supports state priorities. We suggest policy and management actions that can increase the integration of NPS WQT with statewide watershed management goals, and could ultimately improve environmental returns from this fast-growing program.

Quantifying background nitrate removal mechanisms in an agricultural watershed with contrasting subcatchment baseflow concentrations.

Numerous studies have documented the linkages between agricultural nitrogen loads and surface water degradation. In contrast, potential water quality improvements due to agricultural best management practices are difficult to detect because of the confounding effect of background nitrate removal rates, as well as the groundwater-driven delay between land surface action and stream response. To characterize background controls on nitrate removal in two agricultural catchments, we calibrated groundwater travel time distributions with subsurface environmental tracer data to quantify the lag time between historic agricultural inputs and measured baseflow nitrate. We then estimated spatially distributed loading to the water table from nitrate measurements at monitoring wells, using machine learning techniques to extrapolate the loading to unmonitored portions of the catchment to subsequently estimate catchment removal controls. Multiple models agree that in-stream processes remove as much as 75% of incoming loads for one subcatchment while removing <20% of incoming loads for the other. The use of a spatially variable loading field did not result in meaningfully different optimized parameter estimates or model performance when compared with spatially constant loading derived directly from a county-scale agricultural nitrogen budget. Although previous studies using individual well measurements have shown that subsurface denitrification due to contact with a reducing argillaceous confining unit plays an important role in nitrate removal, the catchment-scale contribution of this process is difficult to quantify given the available data. Nonetheless, the study provides a baseline characterization of nitrate transport timescales and removal mechanisms that will support future efforts to detect water quality benefits from ongoing best management practice implementation.

Patient perspectives on neuromyelitis optica spectrum disorders: Data from the PatientsLikeMe online community.

BACKGROUND: Few studies have evaluated patient perspectives on neuromyelitis optica (NMO) and NMO spectrum disorder (NMOSD). OBJECTIVE: Describe patient-reported clinical and treatment experience in NMOSD and compare disease characteristics of NMOSD with those of multiple sclerosis (MS). METHODS: This retrospective, observational study included 522 members with NMO or NMOSD (hereafter collectively referred to as NMOSD) from PatientsLikeMe (PLM), an online patient community. Data describing member demographics, symptoms, and treatments were collected, analysed descriptively, and compared with data from PLM members with MS. RESULTS: Fatigue, pain, and stiffness/spasticity were each rated as moderate to severe by more than half of NMOSD members, and 59% reported that their health limited the type of work or other activities they could perform all or most of the time. Overall, symptom severity and disability levels were comparable between NMOSD and MS members; however, NMOSD members were more likely than MS members to attribute disability to vision-related symptoms and were less likely to report moderate to severe cognitive and emotional symptoms, including brain fog, depressed or anxious mood, and emotional lability. CONCLUSION: This analysis underscores the challenges of living with fatigue, pain, stiffness/spasticity, and visual difficulties, prevalent NMOSD symptoms among members of the PLM community.

Time for a change in how new antibiotics are reimbursed: Development of an insurance framework for funding new antibiotics based on a policy of risk mitigation.

Healthcare systems depend on the availability of new antibiotics. However, there is a lack of treatments for infections caused by multidrug resistant (MDR) pathogens and a weak development pipeline of new therapies. One core challenge to the development of new antibiotics targeting MDR pathogens is that expected revenues are insufficient to drive long-term investment. In the USA and Europe, financial incentives have focussed on supporting R&D, reducing regulatory burden, and extending market exclusivity. Using resistance data to estimate global revenues, we demonstrate that the combined effects of these incentives are unlikely to rekindle investment in antibiotics. We analyse two supplemental approaches: a commercial incentive (a premium price model) and a new business model (an insurance model). A premium price model is familiar and readily implemented but the required price and local budget impact is highly uncertain and sensitive to cross-sectional and longitudinal variation in prevalence of antibiotic resistance. An insurance model delivering risk mitigation for payers, providers and manufacturers would provide an incentive to drive investment in the development of new antibiotics while also facilitating antibiotic conservation. We suggest significant efforts should be made to test the insurance model as one route to stimulate investment in novel antibiotics.

Essential role of histidine 20 in the catalytic mechanism of Escherichia coli peptidyl-tRNA hydrolase.

The peptidyl-tRNA hydrolase (Pth) enzyme plays an essential role in recycling tRNA from peptidyl-tRNA that has prematurely dissociated from the ribosome. In this study of Escherichia coli Pth, the critical role of histidine 20 was investigated by site-directed mutagenesis, stopped-flow kinetic measurements, and chemical modification. The histidine residue at position 20 is known to play an important role in the hydrolysis reaction, but stopped-flow fluorescence measurements showed that, although the His20Asn Pth mutant enzyme was unable to hydrolyze the substrate, the enzyme retained the ability to bind peptidyl-tRNA. Chemical modification of Pth with diethyl pyrocarbonate (DEPC) showed that a residue, with a pK(a) value of 6.3, was essential for substrate hydrolysis and that the stoichiometry of inhibition was 0.70 +/- 0.06 mol of DEPC/mol of enzyme, indicating that modification of only a single residue by DEPC was responsible for the loss of activity. Parallel chemical modification studies with the His20Asn and Asp93Asn mutant enzymes showed that this essential residue was His20. These studies indicate that histidine 20 acts as the catalytic base in the hydrolysis of peptidyl-tRNA by Pth.

Hydrogen-bonding in 2-aminobenzoyl-alpha-chymotrypsin formed by acylation of the enzyme with isatoic anhydride: IR and mass spectroscopic studies.

The acyl-enzyme formed upon acylation of alpha-chymotrypsin with isatoic anhydride has been characterised by infrared spectroscopy. Acylation at pH 7 to yield the 2-aminobenzoyl-enzyme is rapid (k = 5.57x 10(-2)s(-1)), while deacylation is much slower (k =3.7 x 10(-5)10(-2) (s-). The [1C=O]-labelled form of isatoic anhydride has been synthesised, to allow construction of [72C=O]- minus [13C=O]difference spectra; these highlight the carbonyl absorbance of the ligand and eliminate spectral effects that arise from protein perturbation. The ester carbonyl band of the acyl-enzyme absorbs at a wavenumber of 1695cm(-1) and has been shown by deconvolution analysis to represent a single, well-defined conformation. Model studies of ethyl 2-aminobenzoate in a range of solvents show that its carbonyl group is in a hexane-like environment (that is, very nonpolar). It is proposed that the low wavenumber of the carbonyl absorbance arises from the presence of an internal hydrogen bond between the 2-amino group and the ester carbonyl oxygen; this leads to polarisation of the carbonyl group both in the enzyme and in nonpolar solvents. However, in view of the slow deacylation, it is clear that the acyl group is in a nonproductive conformation, with no interaction with the oxyanion hole, and that deacylation occurs from this form or from a minor, invisible form. The infrared data have been supported by kinetic electrospray mass spectroscopic measurements, which demonstrate that the acyl-enzyme is that previously anticipated, and by molecular modelling of 2-aminobenzoyl-alpha-chymotrypsin. It is concluded from pH-dependence measurements that general base catalysis by the 2-amino group is not involved in deacylation.