Citation Context

...at comprise the DOC in a water sample. SUVA is, therefore, a parameter that indicates the nature or “quality” of DOC in a given sample and has been used as a surrogate measurement of DOC aromaticity (=-=Chin et al. 1994-=-; Weishaar et al. 2003). SUVA values at 254 nm (SUVA254) are reported in the current work because natural organic matter absorbs strongly at this wavelength, thereby giving increased sensitivity, and ...

Citation Context

...al mercury (THg), and subsequent mercury methylation, is widely recognized as originating from mostly anthropogenic sources that have exceeded natural inputs since the onset of the industrial period (=-=Fitzgerald et al. 1998-=-). The transport and fate of this deposition as a toxic contaminant to aquatic and terrestrial food webs is a longstanding and critical global environmental issue (Morel et al. 1998). In forested area...

Citation Context

...ovement of organic matter (OM) in both dissolved and particulate form (Shanley et al. 1999; Hurley et al. 1998; Driscoll et al. 1995). Although dissolved OM competes with sulfide for mercury binding (=-=Ravichandran 2004-=-), the presence of reduced sulfur sites within natural OM has been suggested as largely responsible for the strong binding of Hg to OM and facilitates the transport of dissolved Hg in natural waters (...

Citation Context

...fic ultraviolet absorbance (SUVA, described in the Appendix) is an indicator of the character or quality of the DOC and a proxy measurement of the aromaticity or “reactiveness” with chemical species (=-=Weishaar et al. 2003-=-). The SUVA results indicate that the DOC in the streamwater becomes more aromatic with increasing discharge during the snowmelt season (approximately 0.007 per mm/h of discharge) (Fig. 5). However, t...

Citation Context

...r Soil Pollut (2008) 187:89–108 91 sites as possible at the highest frequencies at peak flows, regardless of time of day. Surface water samples were collected according to established USGS protocols (=-=Wilde et al. 1998-=-) and appropriate clean techniques were used for collection of lowconcentration analytes (Horowitz et al. 1994), including the use of particle-free plastic gloves, acid-cleaned 1-L Teflon1 bottles (fo...

Citation Context

... If sulfide is present, then the dominant Hg complex is hydrogen sulfide (S−). If sulfide is absent, the dominant Hg complex is Hg–DOC (Benoit et al. 2001a; Haitzer et al. 2002; Reddy and Aiken 2001; =-=Gilmour et al. 1998-=-). A number of studies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM) in both dissolved and particulate form (Shanley et al. 1999; Hu...

Citation Context

...f time of day. Surface water samples were collected according to established USGS protocols (Wilde et al. 1998) and appropriate clean techniques were used for collection of lowconcentration analytes (=-=Horowitz et al. 1994-=-), including the use of particle-free plastic gloves, acid-cleaned 1-L Teflon1 bottles (for Hg) and pre-combusted glass amber bottles (for DOC). Water was collected in the centroid of stream flow afte...

Citation Context

...cipitation, throughfall, dry deposition, and litterfall. While some THg may be revolatilized, a major export mechanism of THg from the watershed is particle-associated THg transported by streamwater (=-=Grigal 2002-=-). To effectively mitigate ecological consequences of Hg contamination, an understanding of Hg cycling at the watershed scale is needed. The watershed or catchment approach provides datasets that can ...

Citation Context

... pooled catchments during the 3-year study. The pooled results contain outliers within the datasets, thus both the standard Pearson linear regression and the Spearman rank regression were calculated (=-=McCall 1986-=-). The Spearman rank regression improved the correlations among the dissolved and particulate phases of organic carbon and mercury by 12 and 30%, respectively. Because about half of the annual Sleeper...

Citation Context

...dies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM) in both dissolved and particulate form (Shanley et al. 1999; Hurley et al. 1998; =-=Driscoll et al. 1995-=-). Although dissolved OM competes with sulfide for mercury binding (Ravichandran 2004), the presence of reduced sulfur sites within natural OM has been suggested as largely responsible for the strong ...

Citation Context

...trial period (Fitzgerald et al. 1998). The transport and fate of this deposition as a toxic contaminant to aquatic and terrestrial food webs is a longstanding and critical global environmental issue (=-=Morel et al. 1998-=-). In forested areas, atmospheric deposition of THg to soils is in the forms of precipitation, throughfall, dry deposition, and litterfall. While some THg may be revolatilized, a major export mechanis...

Citation Context

...s well-buffered streamwater (Hornbeck et al. 1997). The average baseflow alkalinity is 60 mg/L and pHs are about 7.5, resulting in circumneutral streamwater that would tend to limit mercury mobility (=-=Driscoll et al. 2003-=-). Thus, the mercury behavior described for the Sleepers 90 Water Air Soil Pollut (2008) 187:89–108 River watershed could be potentially more dynamic in the more common acidic systems of the northeast...

Citation Context

...nts of DOC and possibly sulfide (depending on redox conditions). If sulfide is present, then the dominant Hg complex is hydrogen sulfide (S−). If sulfide is absent, the dominant Hg complex is Hg–DOC (=-=Benoit et al. 2001-=-a; Haitzer et al. 2002; Reddy and Aiken 2001; Gilmour et al. 1998). A number of studies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM...

Citation Context

...n during the seasonal period of active snowmelt and that groundwater is also a major component of saturated overland flow in the associated riparian areas (Shanley et al. 1995; McDonnell et al. 1998; =-=McGlynn et al. 1999-=-). About one-half of the annual stream discharge from the watershed occurs during a 6-week snowmelt period from late March to early May (Fig. 2). Sustained high water tables during the snowmelt period...

Citation Context

...highest in the upland catchments (Fig. 3), consistent with the highest density of wetlands. Second, there are four important sources of meHg; precipitation, runoff from wetlands, in-lake methylation (=-=Rudd 1995-=-), and in-stream methylation. Methylmercury concentrations in precipitation are generally minimal in this region (0.03– 0.05 ng/L) (Sakamoto et al. 2001; Allan et al. 2001) and there are no lakes in t...

Citation Context

...nts of DOC and possibly sulfide (depending on redox conditions). If sulfide is present, then the dominant Hg complex is hydrogen sulfide (S−). If sulfide is absent, the dominant Hg complex is Hg–DOC (=-=Benoit et al. 2001-=-a; Haitzer et al. 2002; Reddy and Aiken 2001; Gilmour et al. 1998). A number of studies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM...

Citation Context

...l. 4.2 The Importance of Particulate Organic Carbon in the Transport of Mercury Mercury transport by particulates has been shown to dominate the THg flux in some watersheds (Aastrup and Johnson 1991; =-=Scherbatskoy et al. 1998-=-). Flowweighted averages of the relative contribution of PHg to THg during peak snowmelt showed that PHg systematically increased from slightly more than 40% in the upland catchments to about 80% at W...

Citation Context

...ourth order and are well buffered by carbonates in the bedrock and till, and dominant soils are spodosols and inceptisols. A more detailed description of watershed characteristics is given elsewhere (=-=Shanley and Chalmers 1999-=-; Shanley et al. 2002). The Sleepers River watershed receives more than 1,000 mm of precipitation per year, of which approximately 30% falls as snow. Isotopic evidence indicates that groundwater disch...

Citation Context

...lean lab observing clean hands/dirty hands protocols. Field season 2002, Laboratory Analysis For the field season 2002, DHg, DmeHg, PHg, and PmeHg were determined at the WDML (USEPA Method 1631 1996; =-=DeWild et al. 2002-=-, 2004; Olson and DeWild 1999; Olund et al. 2004). Analyses for total Hg were performed with Dual Amalgamation Cold Vapor Atomic Fluorescence Spectrometry (USEPA Method 1631 1996) with slight modifica...

Citation Context

... thawed surface soil. The surface soil also is enriched in THg from dry deposition and litterfall prior to snowpack development (Rasmussen 1995) and DOC from litterfall decomposition and degradation (=-=Hongve 1999-=-). Clockwise hysteresis in the riparian groundwater– streamflow relation (McDonnell et al. 1998) (water table is closer to the surface for a given flow on the rising limb of the hydrograph compared to...

Citation Context

...ked to organic carbon (OC) quantity and quality. The Sleepers River watershed is considered an end member among research catchments in the New England region because of its well-buffered streamwater (=-=Hornbeck et al. 1997-=-). The average baseflow alkalinity is 60 mg/L and pHs are about 7.5, resulting in circumneutral streamwater that would tend to limit mercury mobility (Driscoll et al. 2003). Thus, the mercury behavior...

Citation Context

...d to 14CH4 + 14CO2], normalized per day and per gram of wet sediment. Descriptions of meHg production and degradation potential rate assays are given elsewhere (Marvin-DiPasquale and Agee 2003; Marvin=-=DiPasquale et al. 2003-=-) (see further readings). Briefly, all sediment was initially homogenized and sub-sampled in an anoxic (N2 flushed) glove bag. Rates of microbial SR, Hg(II)-methylation and MeHg degradation were measu...

Citation Context

...r re-suspended during spring snowmelt or summer storms. The linked behavior of THg and TmeHg at 98 Water Air Soil Pollut (2008) 187:89–108 Sleepers River differs from that in Scandinavian catchments (=-=Bishop et al. 1995-=-a,b,c; Lee et al. 1995a,b; Munthe et al. 1995) where an inverse correlation suggests THg and TmeHg are decoupled (THg increases but TmeHg dilutes with increasing flow). The decoupling of THg and TmeHg...

Citation Context

...solved and particulate organic carbon concentrations. 4.1 Mercury–Carbon Dynamics Similar to findings from numerous other studies (Shanley et al. 1999, 2002; Hurley et al. 1998; Driscoll et al. 1995; =-=Krabbenhoft et al. 1995-=-; Maurice-Bourgoin et al. 2003; Balogh et al. 2000; Cowell et al. 1995), results from surface water sampling during three consecutive snowmelt seasons (2000–2002) showed a positive correlation between...

Citation Context

...98). A number of studies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM) in both dissolved and particulate form (Shanley et al. 1999; =-=Hurley et al. 1998-=-; Driscoll et al. 1995). Although dissolved OM competes with sulfide for mercury binding (Ravichandran 2004), the presence of reduced sulfur sites within natural OM has been suggested as largely respo...

Citation Context

... the first year of study, observed patterns of mercury and organic carbon dynamics were consistent across a set of 10 forested and agricultural catchments of different size, land cover, and land use (=-=Shanley et al. 2002-=-). This paper reports the findings of two additional years of studies built on these findings using the catchment approach to monitor high-flow dynamics and mercury methylation in uplands. The second ...

Citation Context

... to be the dominant control. 4.2 The Importance of Particulate Organic Carbon in the Transport of Mercury Mercury transport by particulates has been shown to dominate the THg flux in some watersheds (=-=Aastrup and Johnson 1991-=-; Scherbatskoy et al. 1998). Flowweighted averages of the relative contribution of PHg to THg during peak snowmelt showed that PHg systematically increased from slightly more than 40% in the upland ca...

Citation Context

...r re-suspended during spring snowmelt or summer storms. The linked behavior of THg and TmeHg at 98 Water Air Soil Pollut (2008) 187:89–108 Sleepers River differs from that in Scandinavian catchments (=-=Bishop et al. 1995-=-a,b,c; Lee et al. 1995a,b; Munthe et al. 1995) where an inverse correlation suggests THg and TmeHg are decoupled (THg increases but TmeHg dilutes with increasing flow). The decoupling of THg and TmeHg...

Citation Context

...urce of meHg while Hg is delivered via surficial pathways that flush the organic soils. When considering meHg production in a catchment, wetland density is considered to be the most important factor (=-=Hurley et al. 1995-=-; Krabbenhoft et al. 1995). It is generally thought that most of the meHg in a catchment is likely produced in zones that have anoxic conditions but also have concentrations of sulfide that are optima...

Citation Context

... on redox conditions). If sulfide is present, then the dominant Hg complex is hydrogen sulfide (S−). If sulfide is absent, the dominant Hg complex is Hg–DOC (Benoit et al. 2001a; Haitzer et al. 2002; =-=Reddy and Aiken 2001-=-; Gilmour et al. 1998). A number of studies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM) in both dissolved and particulate form (Sh...

Citation Context

...ols. Field season 2002, Laboratory Analysis For the field season 2002, DHg, DmeHg, PHg, and PmeHg were determined at the WDML (USEPA Method 1631 1996; DeWild et al. 2002, 2004; Olson and DeWild 1999; =-=Olund et al. 2004-=-). Analyses for total Hg were performed with Dual Amalgamation Cold Vapor Atomic Fluorescence Spectrometry (USEPA Method 1631 1996) with slight modifications for particulate analyses http://infotrek.e...

Citation Context

...ands/dirty hands protocols. Field season 2002, Laboratory Analysis For the field season 2002, DHg, DmeHg, PHg, and PmeHg were determined at the WDML (USEPA Method 1631 1996; DeWild et al. 2002, 2004; =-=Olson and DeWild 1999-=-; Olund et al. 2004). Analyses for total Hg were performed with Dual Amalgamation Cold Vapor Atomic Fluorescence Spectrometry (USEPA Method 1631 1996) with slight modifications for particulate analyse...

Citation Context

... stream– water samples from catchments W-9B, W-2, and W-3 during the 2001 snowmelt season. Other northeastern streams and lakes are primarily dominated by the hydrophobic acid fraction (HPOA) of DOC (=-=David and Vance 1991-=-; Moore 2003. This is also the case in the Sleepers River watershed; the HPOA isolate was the major component of the total DOC (median value 50%, range 30–60%) and its fraction percent of the total DO...

Citation Context

...ly sulfide (depending on redox conditions). If sulfide is present, then the dominant Hg complex is hydrogen sulfide (S−). If sulfide is absent, the dominant Hg complex is Hg–DOC (Benoit et al. 2001a; =-=Haitzer et al. 2002-=-; Reddy and Aiken 2001; Gilmour et al. 1998). A number of studies have shown that Hg transport through a watershed is generally associated with the movement of organic matter (OM) in both dissolved an...

Citation Context

...and particulate carbon (PC) concentrations (USEPA 1997. Method No. 440.0). Generally, it is assumed that particulate inorganic carbon (PIC) is negligible compared to particulate organic carbon (POC) (=-=Keefe 1994-=-). PIC was determined on four samples from different streams during the 2003 snowmelt; 0.6, 2.0, 3.3, and 13.8% of PC (Shanley and Chalmers, USGS, written commun.), thus PC was assumed to represent pa...

Citation Context

...ing snowmelt or summer storms. The linked behavior of THg and TmeHg at 98 Water Air Soil Pollut (2008) 187:89–108 Sleepers River differs from that in Scandinavian catchments (Bishop et al. 1995a,b,c; =-=Lee et al. 1995-=-a,b; Munthe et al. 1995) where an inverse correlation suggests THg and TmeHg are decoupled (THg increases but TmeHg dilutes with increasing flow). The decoupling of THg and TmeHg observed in Scandinav...

Citation Context

...water tables during the snowmelt period cause the flushing of mineral and organic soils and results in more than half of the annual stream–water flux of weathering solutes during the snowmelt period (=-=Peters et al. 2006-=-). Flashy discharge typically occurs during convective summer storms from about June to October (Shanley and Chalmers 1999). 3 Methods Each catchment sampled in the Sleepers River watershed was instru...

Citation Context

... from catchments W-9B, W-2, and W-3 during the 2001 snowmelt season. Other northeastern streams and lakes are primarily dominated by the hydrophobic acid fraction (HPOA) of DOC (David and Vance 1991; =-=Moore 2003-=-. This is also the case in the Sleepers River watershed; the HPOA isolate was the major component of the total DOC (median value 50%, range 30–60%) and its fraction percent of the total DOC had a stro...

Citation Context

...n many areas. Snowmelt with elevated THg concentrations infiltrates the thawed surface soil. The surface soil also is enriched in THg from dry deposition and litterfall prior to snowpack development (=-=Rasmussen 1995-=-) and DOC from litterfall decomposition and degradation (Hongve 1999). Clockwise hysteresis in the riparian groundwater– streamflow relation (McDonnell et al. 1998) (water table is closer to the surfa...

Citation Context

... It is generally accepted among researchers that inorganic divalent mercury (Hg(II)) and Hg(II) complexes (hereafter referred to as Hg(II)) are the predominant forms of Hg in soils and surface water (=-=Skyllberg et al. 2000-=-; Grigal 2002). In the absence of DOC and sulfide, mercury complexes to form HgOH+ and HgCll+ in most natural surface waters. However, many surface waters contain substantial amounts of DOC and possib...

Citation Context

... anion and DOC analyses were filtered from the 1-L amber bottles using a 60 mL Becton Dickinson2 plastic syringe with Luer-lok fitting and a 25 mm Gelman Acrodisk filter with 0.45 μm SUPOR™ membrane (=-=Babiarz et al. 2000-=-) into 40 mL baked, amber glass vials with Teflon lined caps (DOC) and clean 125 mL high density polyethylene bottles. All samples were collected in duplicate. The samples were shipped chilled to the ...

Citation Context

...ction and processing The well-mixed sample was filtered through a 0.40 μm pore-size Nuclepore polycarbonate membrane filter™, using a vacuum filter apparatus made from polytetrafloro-ethylene (PTFE) (=-=Kelly and Taylor 1996-=-). The protocol used for the filtration to minimize artifactual contamination included: (1) the filter apparatus was thoroughly cleaned with 1% HNO3 and rinsed with deionized water; (2) a new 0.40-μm ...

Citation Context

...ganic carbon concentrations. 4.1 Mercury–Carbon Dynamics Similar to findings from numerous other studies (Shanley et al. 1999, 2002; Hurley et al. 1998; Driscoll et al. 1995; Krabbenhoft et al. 1995; =-=Maurice-Bourgoin et al. 2003-=-; Balogh et al. 2000; Cowell et al. 1995), results from surface water sampling during three consecutive snowmelt seasons (2000–2002) showed a positive correlation between DHg and DOC (Fig. 4a); there ...

Citation Context

...er storms. The linked behavior of THg and TmeHg at 98 Water Air Soil Pollut (2008) 187:89–108 Sleepers River differs from that in Scandinavian catchments (Bishop et al. 1995a,b,c; Lee et al. 1995a,b; =-=Munthe et al. 1995-=-) where an inverse correlation suggests THg and TmeHg are decoupled (THg increases but TmeHg dilutes with increasing flow). The decoupling of THg and TmeHg observed in Scandinavian streams argues for ...

Citation Context

... from wetlands, in-lake methylation (Rudd 1995), and in-stream methylation. Methylmercury concentrations in precipitation are generally minimal in this region (0.03– 0.05 ng/L) (Sakamoto et al. 2001; =-=Allan et al. 2001-=-) and there are no lakes in the Sleepers River watershed. There are, however, several upland wetlands and stream sediment zones that could be conducive to Hg methylation. Third, there are several key ...

Citation Context

....1 Mercury–Carbon Dynamics Similar to findings from numerous other studies (Shanley et al. 1999, 2002; Hurley et al. 1998; Driscoll et al. 1995; Krabbenhoft et al. 1995; Maurice-Bourgoin et al. 2003; =-=Balogh et al. 2000-=-; Cowell et al. 1995), results from surface water sampling during three consecutive snowmelt seasons (2000–2002) showed a positive correlation between DHg and DOC (Fig. 4a); there is also a significan...

Citation Context

...r re-suspended during spring snowmelt or summer storms. The linked behavior of THg and TmeHg at 98 Water Air Soil Pollut (2008) 187:89–108 Sleepers River differs from that in Scandinavian catchments (=-=Bishop et al. 1995-=-a,b,c; Lee et al. 1995a,b; Munthe et al. 1995) where an inverse correlation suggests THg and TmeHg are decoupled (THg increases but TmeHg dilutes with increasing flow). The decoupling of THg and TmeHg...

Citation Context

...2002) also summarized that the DHg intercept at zero DOC is 11–13 ng/L for interflow. Although the sorptive properties of the surface soils are likely to influence the amount of DHg in stream waters (=-=Ussiri and Johnson 2004-=-), the intercept for Sleepers River streamwater is very near zero (0.3) DHg, suggesting that the sources of DHg during the spring snowmelt flush in the upland catchments of the watershed originate lar...

Citation Context

...namics Similar to findings from numerous other studies (Shanley et al. 1999, 2002; Hurley et al. 1998; Driscoll et al. 1995; Krabbenhoft et al. 1995; Maurice-Bourgoin et al. 2003; Balogh et al. 2000; =-=Cowell et al. 1995-=-), results from surface water sampling during three consecutive snowmelt seasons (2000–2002) showed a positive correlation between DHg and DOC (Fig. 4a); there is also a significant positive correlati...

Citation Context

... samples were brought to the laboratory and incubated for determination of meHg production potential and degradation potential rates using 203Hg(II) and 14CH3HgI radiotracer amendments, respectively (=-=Marvin-DiPasquale and Agee 2003-=-). The July samples were also measured for THg and total methylmercury (TmeHg). Table 1 provides a definition of the numerous abbreviations used throughout this paper. Quality assurance and a detailed...

Citation Context

...major component of the total DOC (median value 50%, range 30–60%) and its fraction percent of the total DOC had a strong positive correlation to DOC concentration (r2>0.85); similar to other systems (=-=Mattsson et al. 1998-=-). The relation between DHg and the concentration of HPOA was statistically significant (r2=0.55, p=0.01 for all data points) (Fig. 6a). Benoit et al. (2001a) showed that DOM isolates (e.g. HPOA) are ...

Citation Context

...nent of streamwater even during the seasonal period of active snowmelt and that groundwater is also a major component of saturated overland flow in the associated riparian areas (Shanley et al. 1995; =-=McDonnell et al. 1998-=-; McGlynn et al. 1999). About one-half of the annual stream discharge from the watershed occurs during a 6-week snowmelt period from late March to early May (Fig. 2). Sustained high water tables durin...

Citation Context

... precipitation, runoff from wetlands, in-lake methylation (Rudd 1995), and in-stream methylation. Methylmercury concentrations in precipitation are generally minimal in this region (0.03– 0.05 ng/L) (=-=Sakamoto et al. 2001-=-; Allan et al. 2001) and there are no lakes in the Sleepers River watershed. There are, however, several upland wetlands and stream sediment zones that could be conducive to Hg methylation. Third, the...

Citation Context

...produced in zones that have anoxic conditions but also have concentrations of sulfide that are optimal for mercury methylation (Lee et al. 1995a, 2000; Bishop et al. 1995b; Benoit et al. 2001b, 2003; =-=Schwesig et al. 1999-=-; Gilmour et al. 1998). Despite a decrease in the wetland cover (calculated from mucky soil types) from about 5% for the upland catchment W-9BX (0.05 km2) to about 1% for the Sleepers River watershed ...

Citation Context

...duced sulfur sites within natural OM has been suggested as largely responsible for the strong binding of Hg to OM and facilitates the transport of dissolved Hg in natural waters (Haitzer et al. 2002; =-=Skyllberg et al. 2003-=-). Thus, a low-sulfide aquatic environment with dissolved organic matter (DOM) enriched in reduced sulfur functional groups would be conducive to complexation of Hg to DOM (Skyllberg et al. 2003; Beno...

Citation Context

...ing a stainless steel spoon and clean-hands protocol, soil was scraped and placed into 40-mL baked, amber glass vials with Teflon lined caps. Samples were stored frozen until processing and analysis (=-=USEPA 1994-=-). Six soil and stream sediment samples were collected in three “zones” (stream, riparian, and wetland) within the W-9 catchment during the April 2002 spring snowmelt and again in July 2003; at shallo...

Citation Context

...on. Subsequently, samples were stored and chilled until further analysis. Suspended sediment was collected on glass fiber filters and analyzed for sediment and particulate carbon (PC) concentrations (=-=USEPA 1997-=-. Method No. 440.0). Generally, it is assumed that particulate inorganic carbon (PIC) is negligible compared to particulate organic carbon (POC) (Keefe 1994). PIC was determined on four samples from d...