skip to main content

Title: Hubbard Brook Experimental Forest: Watershed 3 – One year of resin-extracted solutes from variably saturated soils
Hbr363: WS3 One year of resin-extracted solutes from variably saturated soils The Lateral Weathering Study looks at spatial patterns of mineral weathering processes at Hubbard Brook Experimental Forest. ThisMore>>
; ; ;
Environmental Data Initiative
Publication Year:
Award ID(s):
1643327 1637685
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract
    Excessive phosphorus (P) applications to croplands can contribute to eutrophication of surface waters through surface runoff and subsurface (leaching) losses. We analyzed leaching losses of total dissolved P (TDP) from no-till corn, hybrid poplar (Populus nigra X P. maximowiczii), switchgrass (Panicum virgatum), miscanthus (Miscanthus giganteus), native grasses, and restored prairie, all planted in 2008 on former cropland in Michigan, USA. All crops except corn (13 kg P ha−1 year−1) were grown without P fertilization. Biomass was harvested at the end of each growing season except for poplar. Soil water at 1.2 m depth was sampled weekly to biweekly for TDP determination during March–November 2009–2016 using tension lysimeters. Soil test P (0–25 cm depth) was measured every autumn. Soil water TDP concentrations were usually below levels where eutrophication of surface waters is frequently observed (> 0.02 mg L−1) but often higher than in deep groundwater or nearby streams and lakes. Rates of P leaching, estimated from measured concentrations and modeled drainage, did not differ statistically among cropping systems across years; 7-year cropping system means ranged from 0.035 to 0.072 kg P ha−1 year−1 with large interannual variation. Leached P was positively related to STP, which decreased over the 7 years in all systems. These results indicate that both P-fertilized and unfertilized cropping systems mayMore>>
  2. Abstract
    Site description. This data package consists of data obtained from sampling surface soil (the 0-7.6 cm depth profile) in black mangrove (Avicennia germinans) dominated forest and black needlerush (Juncus roemerianus) saltmarsh along the Gulf of Mexico coastline in peninsular west-central Florida, USA. This location has a subtropical climate with mean daily temperatures ranging from 15.4 °C in January to 27.8 °C in August, and annual precipitation of 1336 mm. Precipitation falls as rain primarily between June and September. Tides are semi-diurnal, with 0.57 m median amplitudes during the year preceding sampling (U.S. NOAA National Ocean Service, Clearwater Beach, Florida, station 8726724). Sea-level rise is 4.0 ± 0.6 mm per year (1973-2020 trend, mean ± 95 % confidence interval, NOAA NOS Clearwater Beach station). The A. germinans mangrove zone is either adjacent to water or fringed on the seaward side by a narrow band of red mangrove (Rhizophora mangle). A near-monoculture of J. roemerianus is often adjacent to and immediately landward of the A. germinans zone. The transition from the mangrove to the J. roemerianus zone is variable in our study area. An abrupt edge between closed-canopy mangrove and J. roemerianus monoculture may extend for up to several hundred metersMore>>
  3. Soil biota generate CO2 that can vertically export to the atmosphere, and dissolved organic and inorganic carbon (DOC and DIC) that can laterally export to streams and accelerate weathering. These processes are regulated by external hydroclimate forcing and internal structures (permeability distribution), the relative influences of which are rarely studied. Understanding these interactions is essential a hydrological extremes intensify in the future. Here we explore the question: How and to what extent do hydrological and permeability distribution conditions regulate soil carbon transformations and chemical weathering? We address the questions using a hillslope reactive transport model constrained by data from the Fitch Forest (Kansas, United States). Numerical experiments were used to mimic hydrological extremes and variable shallow-versus-deep permeability contrasts. Results demonstrate that under dry conditions (0.08 mm/day), long water transit times led to more mineralization of organic carbon (OC) into inorganic carbon (IC) form (>98\%). Of the IC produced, ~ 75\% was emitted upward as CO2 gas and ~ 25\% was exported laterally as DIC into the stream. Wet conditions (8.0 mm/day) resulted in less mineralization (~88\%), more DOC production (~12\%), and more lateral fluxes of IC (~50\% of produced IC). Carbonate precipitated under dry conditions and dissolved under wet conditionsmore »as the fast flow rapidly droves the reaction to disequilibrium. The results depict a conceptual hillslope model that prompts four hypotheses for our community to test. H1: Droughts enhance carbon mineralization and vertical upward carbon fluxes, whereas large hydrological events such as storms and flooding enhance subsurface vertical connectivity, reduce transit times, and promote lateral export. H2: The role of weathering as a net carbon sink or source to the atmosphere depends on the interaction between hydrologic flows and lithology: transition from droughts to storms can shift carbonate from a carbon sink (mineral precipitation) to carbon source (dissolution). H3: Permeability contrasts regulate the lateral flow partitioning via shallow flow paths versus deeper groundwater though this alter reaction rates negligibly. H4: Stream chemistry reflect flow paths and can potentially quantify water transit times: solutes enriched in shallow soils have a younger water signature; solutes abundant at depth carry older water signature.« less
  4. Meteoric waters move along pathways in the subsurface that differ as a function of lithology because of the effects of chemical and physical weathering. To explore how this affects stream chemistry, we investigated watersheds around an igneous intrusion in the Luquillo Mountains (Puerto Rico). We analyzed streams on 1) unmetamorphosed country rock (volcaniclastic sedimentary strata, VC) surrounding an igneous intrusion, 2) the quartz-diorite intrusion (QD), and 3) the metamorphosed aureole rock (hornfels-facies volcaniclastics, HF). These lithologies differ physically and chemically but weather under the same tropical rain forest conditions. The sedimentary VC lithology is pervasively fractured while the massive QD and HF lithologies are relatively unfractured. However, the QD fractures during weathering to produce spheroidally-weathered corestones surrounded by cm-thick rindlets of increasingly weathered rock. Meteoric waters flow pervasively through the network of already-fractured VC rock and the spheroidally weathered rindlets on the QD, but only access a limited fraction of the HF, explaining why streams draining HF are the most dilute in the mountains. This results in various thicknesses of regolith from thick (VC) to moderate (QD) to thin or nonexistent (HF). The pervasive fractures allow groundwater to flow deeply through the VC and then return to the mainstem rivermore »(Río Mameyes) at lower elevations. These “rock waters” drive concentrations of rock-derived solutes (silica, base cations, sulfate, phosphate) higher in the lower reaches of the stream. Water also flows through weathering-induced fractures on the QD at high elevations where rindletted corestones are present in stacks, and this water flux dissolves plagioclase and hornblende and oxidizes biotite. This “QD rock water” is not generated at lower elevations in the Río Icacos watershed, where stacks of corestones are absent, and contributions to stream solutes derive from weathering of feldspar- and hornblende-depleted saprolite. The stream chemistry in the QD-dominated watershed (Río Icacos) thus varies from concentrated QD-rock water at channel heads below steep ridgelines toward more diluted “saprolite water” downstream. These observations emphasize the importance of lithology and fracture patterns in dictating water flowpaths, stream chemistry, and regolith development in headwater catchments.« less
  5. This research focuses on the efficiency of recommended heavy use area protection (HUAP) pads installed in poultry houses utilizing the Choptank River, a tributary of the Chesapeake Bay. The Chesapeake Bay watershed is severely affected by crop agriculture and poultry feeding operations. Water quality degradation along with scarcity of water is a significant concern in this area, suggesting a need for changes in both environmental and groundwater management practices. Our objective in this study was to compare the efficiency of HUAP in reducing litter spillage and nutrient runoff between two poultry houses, one of which was constructed in 2005 and the other in 2009. The poultry house constructed in 2005 did not have HUAP pads initially; they were built in 2006. The poultry house built in 2009 had the pads from the starting point. We collected soil and water samples each month and analyzed them for pH, electrical conductivity (EC), nitrate, nitrite, total nitrogen, phosphate, and other soil properties throughout the year. The pH of soil and water samples was in the range of 6.8–8.0 and 6.5–7.2, respectively. We collected six water samples in total in the ditch, from points at retention ponds near the farm ditch to sites inmore »wooded areas on the farm. Water sample B (where ditch water meets retention pond water from the poultry farm) had the highest EC value and nitrate, nitrite, and total nitrogen concentrations compared with other water samples. The subsequent water samples downstream had reduced loads of nutrients. The study results suggest that there was a minimum carryover of nutrients from soil into the runoff water, storm ditches, and adjacent stream. There was also a minimal effect of house cleaning and storm events in raising the concentration of nutrients in soil and water samples at our study sites. The older poultry site had higher total nitrogen and phosphorous surrounding the pads, whereas no elevated levels of nutrients were identified at the newer site. The ability of HUAP pads to hold onto contaminates decreases with age and use. This study also shows that the impacts from poultry activities on surface and groundwater can be minimized by using management practices such as HUAP pads. These practices can reduce pollution in the farm, increase productivity, and save farmers and ranchers time and money in the long run.« less