Search for: All records

Tension-free lysimeters were installed in three soil horizons at three locations adjacent to Hubbard Brook Experiment Forest Watershed 6. At each location lysimeters were placed beneath the Oa horizon and within the upper and lower B horizon. Soil solution samples were collected approximately monthly and analyzed for pH, acid neutralizing capacity (ANC), base cations, soluble anions, trace metals, nitrogen and carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Longitudinal variation in streamwater chemistry has been measured in two watersheds (W1 and W6) at the Hubbard Brook Experimental Forest. This dataset includes samples that have been collected approximately monthly in Watershed 6 at six sampling locations (1982 - present) along an elevational gradient. Samples are analyzed for pH, ANC, anions, cations, nitrogen, dissolved inorganic and organic carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Tension-free lysimeters were installed in three soil horizons at 13 locations within Hubbard Brook Experimental Forest Watershed 1, representing the variation in elevation and forest type of the watershed. At each location lysimeters were placed beneath the Oa horizon and within the upper and lower B horizon. Soil solution samples were collected approximately monthly and analyzed for pH, acid neutralizing capacity (ANC), base cations, soluble anions, trace metals, nitrogen and carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Longitudinal variation in streamwater chemistry has been measured in two watersheds (W1 and W6) at the Hubbard Brook Experimental Forest. This dataset includes samples that have been collected approximately monthly in Watershed 1 at five sampling locations (1991 - ongoing) along an elevational gradient. Samples are analyzed for pH, ANC, anions, cations, nitrogen, dissolved inorganic and organic carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Understanding the elemental and structural composition of mercury-dissolved organic matter (Hg-DOM) complexes is crucial for comprehending Hg speciation, bioavailability, and transformations in aquatic ecosystems. However, low concentrations of these organo-metal complexes in natural waters and extraction at acidic pH constrain their characterization. Here, we used solid phase extraction (SPE) methodology to extract Hg-DOM complexes at ambient pH and validated their preconcentration by preserving the composition for identification using ultra-high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). While the dissolved organic carbon (DOC) extraction efficiency was higher with cartridges containing styrene divinylbenzene copolymer (PPL) than silica structure bonded with hydrocarbon chains (C18), Hg in both extracts showed no significant difference. FT-ICR-MS analysis revealed that Hg-DOM complexes extracted by C18 cartridges were aliphatic with smaller carbon chains (16-18), whereas complexes extracted with PPL exhibited both aliphatic and aromatic characteristics with a wide distribution of carbon chains ranging from 17 to 25. The C18 cartridge appeared to be selective in extracting and preserving the nonpolar complexes, as evidenced by the identification of two molecular formulae, C16H31HgNO3 and C16H35HgNO2S, with m/z ratios of 487.2 and 507.21, across triplicate extractions. This study addresses the challenge of the spectroscopic limitation of Hg-DOM identification by extracting these complexes at circumneutral pH and presumably preserving them from dissociation during extraction. 

Longitudinal variation in streamwater chemistry has been measured in two watersheds (W1 and W6) at the Hubbard Brook Experimental Forest. This dataset includes samples that have been collected approximately monthly in Watershed 1 at five sampling locations (1991 - ongoing) along an elevational gradient. Samples are analyzed for pH, ANC, anions, cations, nitrogen, dissolved inorganic and organic carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Tension-free lysimeters were installed in three soil horizons at 13 locations within Hubbard Brook Experimental Forest Watershed 1, representing the variation in elevation and forest type of the watershed. At each location lysimeters were placed beneath the Oa horizon and within the upper and lower B horizon. Soil solution samples were collected approximately monthly and analyzed for pH, acid neutralizing capacity (ANC), base cations, soluble anions, trace metals, nitrogen and carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Tension-free lysimeters were installed in three soil horizons at three locations adjacent to Hubbard Brook Experiment Forest Watershed 6. At each location lysimeters were placed beneath the Oa horizon and within the upper and lower B horizon. Soil solution samples were collected approximately monthly and analyzed for pH, acid neutralizing capacity (ANC), base cations, soluble anions, trace metals, nitrogen and carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

Longitudinal variation in streamwater chemistry has been measured in two watersheds (W1 and W6) at the Hubbard Brook Experimental Forest. This dataset includes samples that have been collected approximately monthly in Watershed 6 at six sampling locations (1982 - present) along an elevational gradient. Samples are analyzed for pH, ANC, anions, cations, nitrogen, dissolved inorganic and organic carbon. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

The pace and trajectory of ecosystem development are governed by the availability and cycling of limiting nutrients, and anthropogenic disturbances such as acid rain and deforestation alter these trajectories by removing substantial quantities of nutrients via titration or harvest. Here, we use six decades of continuous chemical and hydrologic data from three adjacent headwater catchments in the Hubbard Brook Experimental Forest, New Hampshire—one deforested (W5), one CaSiO₃-enriched (W1), and one reference (W6)—to quantify long-term nutrient and mineral fluxes. Acid deposition since 1900 drove pronounced depletion and export of base cations, particularly calcium, across all watersheds. Experimental deforestation of W5 intensified loss of biomass and nutrient cations and triggered sustained increases in streamwater pH, Ca²⁺, and SiO₂exports over nearly four decades, greatly exceeding the effects of direct CaSiO₃enrichment in both duration and magnitude. We detect no long-term changes in water yield or water flow paths in the experimental watersheds, and we attribute this multidecadal increase in weathering rates following deforestation to biological responses to severe nutrient limitation. Our evidence suggests that in the regrowing forest, plants are investing photosynthate into belowground processes that amplify mineral weathering to access phosphorus and micronutrients, consequently elevating the export of less limiting elements present in silicate parent material. Throughout decades of forest regrowth, enhanced biotic weathering has continued to deplete the acid buffering capacity of the terrestrial ecosystem while the export of weathering products has elevated the pH of the receiving stream.