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Joseph W. Martin

Publications and source records attributed to Joseph W. Martin.

3 recordsLinked to original sources
USGS2018

High frequency data exposes nonlinear seasonal controls on dissolved organic matter in a large watershed

We analyzed a five year, high frequency time series generated by an in situ fluorescent dissolved organic matter (fDOM) sensor installed near the Connecticut River’s mouth, investigating high temporal resolution DOM dynamics in a larger watershed and longer time series than previously addressed. We identified a gradient between large, saturating summer fDOM responses to discharge and linear, subdued responses during colder months. Seasonal response patterns were not consistent with multiple linear regression. Alternatively, we binned measurements across the yearly cycle using environmental indices, such as temperature, and applied moving regression, a novel approach which produced superior fits to calendar day binning. Spatially averaged watershed soil temperature at 10 cm was the best overall index of discharge-fDOM response. DOM fractionation showed fDOM was primarily a surrogate for hydrophobic organic acid (HPOA) concentrations. HPOAs were highly correlated with discharge, but hydrophilics (HPIs) were not. Discharge dependent DOM concentrations driven by the HPOA fraction may be controlled by soil temperature and water table position relative to organic and mineral soil horizons. HPI concentrations were correlated with average watershed soil temperature at 10 cm but were rather stationary throughout the year, further indicating a consistent groundwater source for this nonfluorescent DOM. We present a resolved subseasonal empirical model of DOM concentrations and fluxes, showing that riverine DOM flux and quality depend heavily on seasonal terrestrial carbon dynamics and hydrologic flow paths. High frequency monitoring reveals readily discernible patterns demonstrating that upland biogeochemical signals are maintained even at this large watershed scale.

Environmental Science and Technology↗
USGS2018

Nitrogen concentrations and loads for the Connecticut River at Middle Haddam, Connecticut, computed with the use of autosampling and continuous measurements of water quality for water years 2009 to 2014

The daily and annual loads of nitrate plus nitrite and total nitrogen for the Connecticut River at Middle Haddam, Connecticut, were determined for water years 2009 to 2014. The analysis was done with a combination of methods, which included a predefined rating curve method for nitrate plus nitrite and total nitrogen for water years 2009 to 2011 and a custom rating curve method that included sensor measurements of nitrate plus nitrite nitrogen concentration and turbidity along with mean daily flow to determine total nitrogen loads for water years 2011 to 2014. Instantaneous concentrations of total nitrogen were estimated through the use of a regression model based on sensor measurements at 15-minute intervals of nitrate plus nitrite nitrogen and turbidity for water years 2011 to 2014. Annual total nitrogen loads at the Connecticut River at Middle Haddam ranged from 12,900 to 19,200 metric tons, of which about 42 to 49 percent was in the form of nitrate plus nitrite. The mean 95-percent prediction intervals on daily total nitrogen load estimates were smaller from the custom model, which used sensor data, than those calculated by the predefined model. Annual total nitrogen load estimates at the Connecticut River at Middle Haddam were compared with the upstream load estimates at the Connecticut River at Thompsonville, Conn. Annual gains in total nitrogen loads between the two stations ranged from 3,430 to 6,660 metric tons. These increases between the two stations were attributed to the effects of increased urbanization and to combined annual discharges of 1,540 to 2,090 metric tons of nitrogen from 24 wastewater treatment facilities in the drainage area between the two stations. The contribution of total nitrogen from wastewater discharge between the two stations had declined substantially before the beginning of this study and accounted for from 31 to 52 percent of the gain in nitrogen load between the Thompsonville and Middle Haddam sites.

Connecticut↗
USGS2015

Chloride concentrations, loads, and yields in four watersheds along Interstate 95, southeastern Connecticut, 2008-11: factors that affect peak chloride concentrations during winter storms

Chloride (Cl - ) concentrations and loads and other water chemistry characteristics were assessed to evaluate potential effects of road-deicer applications on streamwater quality in four watersheds along Interstate 95 (I–95) in southeastern Connecticut from November 1, 2008, through September 30, 2011. Streamflow and water quality were studied in the Four Mile River, Oil Mill Brook, Stony Brook, and Jordan Brook watersheds, where developed land ranged from 9 to 32 percent. Water-quality samples were collected and specific conductance was measured continuously at paired water-quality monitoring sites, upstream and downstream from I–95. Specific conductance values were related to Cl - concentrations to assist in determining the effects of road-deicing operations on the levels of Cl - in the streams. Streamflow and water-quality data were compared with weather data and with the timing, amount, and composition of deicers applied to State highways. Grab samples were collected during winter stormwater-runoff events, such as winter storms or periods of rain or warm temperatures in which melting takes place. Grab samples were also collected periodically during the spring and summer and during base-flow conditions. The estimated Cl - concentrations at the eight water-quality monitoring sites during winter storms peaked as high as 270 milligrams per liter (mg/L) and were well below the U.S. Environmental Protection Agency (EPA) recommended acute chloride toxicity criterion of 860 mg/L and the chronic 4-day average toxicity criterion of 230 mg/L. Cl - concentrations in streams, particularly at sites downstream from I–95, peaked during increased streamflow in the winter and early spring as a result of deicers applied to roads and washed off by stormwater or meltwater. Cl - concentrations during most of the nonwinter seasons decreased during increases in streamflow because storm runoff was more dilute than base flow. However, peaks in specific conductance and estimated chloride concentrations at streams in more urbanized watersheds corresponded to peaks in streamflow well after winter snow or ice events; these delayed peaks in Cl - concentration likely resulted from deicer residue that remained in melting snow piles and on roadsides and (or) that were flushed from soils and shallow groundwater, then discharged downstream. Estimated peak Cl - concentrations varied with the type of winter storm event and were highest during or after winter storms of frozen precipitation and rain, in which the rain or meltwater effectively washed off the deicers. Estimated peak Cl - concentrations correlated positively with the duration of deicer application but generally not with streamflow. Estimated peak Cl - concentrations during the winter season were highest during low streamflow at most sites. Chloride concentrations varied considerably in shallow groundwater as a result of land-use differences. Cl - concentrations were very high (as high as 800 mg/L) in shallow groundwater downstream from I–95 at the Four Mile River site. Chloride/bromide mass concentration ratios and the proximity of a former landfill and sewage lagoon upstream indicate a likely source of Cl - is landfill leachate and possibly sewage leachate. Cl - loads in streams generally were highest in the winter and early spring. The estimated daily Cl - yield for the four monitoring sites downstream from I–95 ranged from 0.0004 ton per day per square mile for one of the least developed watersheds to 0.052 ton per day per square mile for the watershed with the highest percentage of urban development and impervious area. The estimated median contribution of Cl - load from atmospheric deposition was small and ranged from 0.07 percent of Cl - load at the Jordan Brook watershed to 0.57 percent at the Oil Mill Brook watershed. The Cl - loads in streams (outputs) were compared with Cl - load inputs, which include atmospheric deposition and deicer applications; Cl - load inputs were slightly larger than the Cl - load outputs at most of the sites during most years but do not account for the Cl - load in groundwater leaving the watersheds. A multiple linear regression model was developed to describe the variability of the natural log of peak specific conductance, as well as estimated Cl - concentrations. Five significant variables best explained the variability in the natural log of the peak specific conductance after deicing events: (1) snow on ground before deicing event; (2) winter precipitation with rain; (3) specific conductance in base flow; (4) State-operated road lane miles divided by watershed area; and (5) amount of Cl - from deicers applied to State-operated roads per lane mile. In this report, winter precipitation is defined as any type of precipitation, including frozen precipitation and rain, that occurs during the active deicing season, typically November through March. Frozen precipitation is defined here as snow, sleet, freezing rain, or any winter precipitation except rain. The addition of a lane mile in both directions on I–95 would result in an estimate of approximately 2 to 11 percent increase in Cl - input from deicers applied to I–95 and other roads maintained by Connecticut Department of Transportation. The largest estimated increase in Cl - load was in the watersheds with the greatest number miles of I–95 corridor relative to the total lane miles maintained by Connecticut Department of Transportation. On the basis of these estimates and the estimated peak Cl - concentrations during the study period, it is unlikely that the increased use of deicers on the additional lanes would lead to Cl - concentrations that exceed the aquatic habitat criteria.

Connecticut↗