8 research outputs found
Stormwater best management practices: Experimental evaluation of chemical cocktails mobilized by freshwater salinization syndrome
Freshwater Salinization Syndrome (FSS) refers to the suite of physical, biological, and chemical impacts of salt ions on the degradation of natural, engineered, and social systems. Impacts of FSS on mobilization of chemical cocktails has been documented in streams and groundwater, but little research has focused on the effects of FSS on stormwater best management practices (BMPs) such as: constructed wetlands, bioswales, ponds, and bioretention. However emerging research suggests that stormwater BMPs may be both sources and sinks of contaminants, shifting seasonally with road salt applications. We conducted lab experiments to investigate this premise; replicate water and soil samples were collected from four distinct stormwater feature types (bioretention, bioswale, constructed wetlands and retention ponds) and were used in salt incubation experiments conducted under six different salinities with three different salts (NaCl, CaCl2, and MgCl2). Increased salt concentrations had profound effects on major and trace element mobilization, with all three salts showing significant positive relationships across nearly all elements analyzed. Across all sites, mean salt retention was 34%, 28%, and 26% for Na+, Mg2+ and Ca2+ respectively, and there were significant differences among stormwater BMPs. Salt type showed preferential mobilization of certain elements. NaCl mobilized Cu, a potent toxicant to aquatic biota, at rates over an order of magnitude greater than both CaCl2 and MgCl2. Stormwater BMP type also had a significant effect on elemental mobilization, with ponds mobilizing significantly more Mn than other sites. However, salt concentration and salt type consistently had significant effects on mean concentrations of elements mobilized across all stormwater BMPs (p < 0.05), suggesting that processes such as ion exchange mobilize metals mobilize metals and salt ions regardless of BMP type. Our results suggest that decisions regarding the amounts and types of salts used as deicers can have significant effects on reducing contaminant mobilization to freshwater ecosystems
Freshwater Salinization Syndrome Alters Nitrogen Transport in Urban Watersheds
Anthropogenic salt inputs have impacted many streams in the U.S. for over a century. Urban stream salinity is often chronically elevated and punctuated by episodic salinization events, which can last hours to days after snowstorms and the application of road salt. Here, we investigated the impacts of freshwater salinization on total dissolved nitrogen (TDN) and NO3â/NO2â concentrations and fluxes across time in urban watersheds in the Baltimore-Washington D.C. metropolitan area of the Chesapeake Bay region. Episodic salinization from road salt applications and snowmelt quickly mobilized TDN in streams likely through soil ion exchange, hydrologic flushing, and other biogeochemical processes. Previous experimental work from other studies has shown that salinization can mobilize nitrogen from sediments, but less work has investigated this phenomenon with high-frequency sensors and targeted monitoring during road salt events. We found that urban streams exhibited elevated concentrations and fluxes of TDN, NO3â/NO2â, and specific conductance that rapidly peaked during and after winter road salt events, and then rapidly declined afterwards. We observed plateaus in TDN concentrations in the ranges of the highest specific conductance values (between 1000 and 2000 ÎŒS/cm) caused by road salt events. Plateaus in TDN concentrations beyond a certain threshold of specific conductance values suggested source limitation of TDN in watersheds (at the highest ranges in chloride concentrations and ranges); salts were likely extracting nitrogen from soils and streams through ion exchange in soils and sediments, ion pairing in soils and waters, and sodium dispersion of soils to a certain threshold level. When watershed transport was compared across land use, including a forested reference watershed, there was a positive relationship between Clâ loads and NO3â/NO2â loads. This relationship occurred across all sites regardless of land use, which suggests that the mass transport of Clâ and NO3â/NO2â are likely influenced by similar factors such as soil ion exchange, ion pairing, sodium dispersion of soils, hydrologic flushing, and biogeochemical processes. Freshwater salinization has the potential to alter the magnitude and timing of total dissolved nitrogen delivery to receiving waters during winter months following road salt applications, and further work should investigate the seasonal relationships of N transport with salinization in urban watersheds
Watershed âchemical cocktailsâ: forming novel elemental combinations in Anthropocene fresh waters
Este artĂculo contiene 25 pĂĄginas, 9 figuras.In the Anthropocene, watershed chemical
transport is increasingly dominated by novel combinations
of elements, which are hydrologically linked
together as âchemical cocktails.â Chemical cocktails
are novel because human activities greatly enhance
elemental concentrations and their probability for
biogeochemical interactions and shared transport
along hydrologic flowpaths. A new chemical cocktail
approach advances our ability to: trace contaminant
mixtures in watersheds, develop chemical proxies
with high-resolution sensor data, and manage multiple
water quality problems. We explore the following
questions: (1) Can we classify elemental transport in
watersheds as chemical cocktails using a new
approach? (2) What is the role of climate and land
use in enhancing the formation and transport of
chemical cocktails in watersheds? To address these
questions, we first analyze trends in concentrations of
carbon, nutrients, metals, and salts in fresh waters over
100 years. Next, we explore how climate and land use
enhance the probability of formation of chemical
cocktails of carbon, nutrients, metals, and salts. Ultimately, we classify transport of chemical cocktails
based on solubility, mobility, reactivity, and dominant
phases: (1) sieved chemical cocktails (e.g., particulate
forms of nutrients, metals and organic matter); (2)
filtered chemical cocktails (e.g., dissolved organic
matter and associated metal complexes); (3) chromatographic
chemical cocktails (e.g., ions eluted from
soil exchange sites); and (4) reactive chemical cocktails
(e.g., limiting nutrients and redox sensitive
elements). Typically, contaminants are regulated and
managed one element at a time, even though combinations
of elements interact to influence many water
quality problems such as toxicity to life, eutrophication,
infrastructure corrosion, and water treatment. A
chemical cocktail approach significantly expands
evaluations of water quality signatures and impacts
beyond single elements to mixtures. High-frequency
sensor data (pH, specific conductance, turbidity, etc.)
can serve as proxies for chemical cocktails and
improve real-time analyses of water quality violations,
identify regulatory needs, and track water quality
recovery following storms and extreme climate
events. Ultimately, a watershed chemical cocktail
approach is necessary for effectively co-managing
groups of contaminants and provides a more holistic
approach for studying, monitoring, and managing
water quality in the Anthropocene.This work was funded by USDA (award
# 2016-67019-25280) and NSF-EPSCoR (#1641157) for
supporting collaborations at the AGU Chapman Conference
on Extreme Climate Events. Significant funding for data
collection/analyses in this paper was provided by NSF
EAR1521224, NSF CBET1058502, NSF Coastal
SEES1426844, NSF DEB-0423476 and DEB-1027188, NSF
RI EPSCoR NEWRnet Grant No. IIA-1330406, EPA ORD,
Chesapeake Bay Trust, and Multi-state Regional Hatch Project
S-1063.Peer reviewe
Novel âchemical cocktails' in inland waters are a consequence of the freshwater salinization syndrome
Five state factors control progressive stages of freshwater salinization syndrome
Abstract Factors driving freshwater salinization syndrome (FSS) influence the severity of impacts and chances for recovery. We hypothesize that spread of FSS across ecosystems is a function of interactions among five state factors: human activities, geology, flowpaths, climate, and time. (1) Human activities drive pulsed or chronic inputs of salt ions and mobilization of chemical contaminants. (2) Geology drives rates of erosion, weathering, ion exchange, and acidificationâalkalinization. (3) Flowpaths drive salinization and contaminant mobilization along hydrologic cycles. (4) Climate drives rising water temperatures, salt stress, and evaporative concentration of ions and saltwater intrusion. (5) Time influences consequences, thresholds, and potentials for ecosystem recovery. We hypothesize that state factors advance FSS in distinct stages, which eventually contribute to failures in systemsâlevel functions (supporting drinking water, crops, biodiversity, infrastructure, etc.). We present future research directions for protecting freshwaters at risk based on five state factors and stages from diagnosis to prognosis to cure
Discovery of 6âFluoro-5â(<i>R</i>)â(3â(<i>S</i>)â(8-fluoro-1-methyl-2,4-dioxo-1,2-dihydroquinazolin-3(4<i>H</i>)âyl)-2-methylphenyl)-2â(<i>S</i>)â(2-hydroxypropan-2-yl)-2,3,4,9-tetrahydroâ1<i>H</i>âcarbazole-8-carboxamide (BMS-986142): A Reversible Inhibitor of Brutonâs Tyrosine Kinase (BTK) Conformationally Constrained by Two Locked Atropisomers
Bruton's tyrosine
kinase (BTK), a nonreceptor tyrosine kinase,
is a member of the Tec family of kinases. BTK plays an essential role
in B cell receptor (BCR)-mediated signaling as well as FcÎł receptor
signaling in monocytes and FcΔ receptor signaling in mast cells
and basophils, all of which have been implicated in the pathophysiology
of autoimmune disease. As a result, inhibition of BTK is anticipated
to provide an effective strategy for the clinical treatment of autoimmune
diseases such as lupus and rheumatoid arthritis. This article details
the structureâactivity relationships (SAR) leading to a novel
series of highly potent and selective carbazole and tetrahydrocarbazole
based, reversible inhibitors of BTK. Of particular interest is that
two atropisomeric centers were rotationally locked to provide a single,
stable atropisomer, resulting in enhanced potency and selectivity
as well as a reduction in safety liabilities. With significantly enhanced
potency and selectivity, excellent in vivo properties and efficacy,
and a very desirable tolerability and safety profile, <b>14f</b> (BMS-986142) was advanced into clinical studies