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  • 1
    Language: English
    In: Biogeochemistry, 2013, Vol.116(1), pp.303-334
    Description: Industrial emissions of SO₂ and NOₓ, resulting in the formation and deposition of sulfuric and nitric acids, affect the health of both terrestrial and aquatic ecosystems. Since the mid-late 20th century, legislation to control acid rain precursors in both Europe and the US has led to significant declines in both SO₄–S and H⁺ in precipitation and streams. However, several authors noted that declines in streamwater SO₄–S did not result in stoichiometric reductions in stream H⁺, and suggested that observed reductions in base cation inputs in precipitation could lessen the effect of air pollution control on improving stream pH. We examined long-term precipitation chemistry (1978–2010) from nearly 30 sites in the US and Europe that are variably affected by acid deposition and that have a variety of industrial and land-use histories to (1) quantify trends in SO₄–S, H⁺, NH₄–N, Ca, and NO₃–N, (2) assess stoichiometry between H⁺ and SO₄–S before and after 1990, and (3) examine regional synchrony of trends. We expected that although the overall efforts of developed countries to reduce air pollution and acid rain by the mid-late 20th century would tend to synchronize precipitation chemistry among regions, geographically varied patterns of fossil fuel use and pollution control measures would produce important asynchronies among European countries and the United States. We also expected that control of particulate versus gaseous emission, along with trends in NH₃ emissions, would be the two most significant factors affecting the stoichiometry between SO₄–S and H⁺. Relationships among H⁺, SO₄–S, NH₄–N, and cations differed markedly between the US and Europe. Controlling for SO₄–S levels, H⁺ in precipitation was significantly lower in Europe than in the US, because (1) alkaline dust loading from the Sahara/Sahel was greater in Europe than the US, and (2) emission of NH₃, which neutralizes acidity upon conversion to NH₄ ⁺, is generally significantly higher in Europe than in the US. Trends in SO₄–S and H⁺ in precipitation were close to stoichometric in the US throughout the period of record, but not in Europe, especially eastern Europe. Ca in precipitation declined significantly before, but not after 1990 in most of the US, but Ca declined in eastern Europe even after 1990. SO₄–S in precipitation was only weakly related to fossil fuel consumption. The stoichiometry of SO₄–S and H⁺ may be explained in part by emission controls, which varied over time and among regions. Control of particulate emissions reduces alkaline particles that neutralize acid precursors as well as S-containing particulates, reducing SO₄–S and Ca more steeply than H⁺, consistent with trends in the northeastern US and Europe before 1990. In contrast, control of gaseous SO₂ emissions results in a stoichiometric relationship between SO₄–S and H⁺, consistent with trends in the US and many western European countries, especially after 1991. However, in many European countries, declining NH₃ emissions contributed to the lack of stoichiometry between SO₄–S and H⁺.Recent reductions in NOₓ emissions have also contributed to declines in H⁺ in precipitation. Future changes in precipitation acidity are likely to depend on multiple factors including trends in NOₓ and NH₃ emission controls, naturally occurring dust, and fossil fuel use, with significant implications for the health of both terrestrial and aquatic ecosystems. ; p. 303-334.
    Keywords: Calcium ; Laws And Regulations ; Particulate Emissions ; Protons ; Particulates ; Nitrogen ; Air Pollution ; Fossil Fuels ; Acid Deposition ; Stoichiometry ; Ph ; Pollution Control ; Sulfur Dioxide ; Acids ; Neutralization ; Energy Use And Consumption ; Ammonia ; Acidity ; Control Methods ; Cations ; Streams ; Aquatic Ecosystems ; Land Use ; Developed Countries ; Sahel
    ISSN: 0168-2563
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  • 2
    Language: English
    In: Forest Ecology and Management, 15 November 2016, Vol.380, pp.11-22
    Description: Dissolved organic matter (DOM) is a critical component of the carbon cycle linking terrestrial and aquatic ecosystems. Although many factors have been identified as influencing DOM fluxes and biochemical quality in rivers with varying land cover types, controls on DOM composition in forested headwater catchments of the western U.S. are poorly understood. This study examined the effect of hydrologic patterns and forest management history on stream DOM chemistry at watersheds located in the H.J. Andrews Experimental Forest of the Oregon Cascades. Specific UV absorbance at 254 nm (SUVA ), generally indicative of aromaticity, increased in streams during storms with increasing surficial soil horizon and litter DOM inputs. Fluorescence excitation and emission matrices (EEMs) with Parallel Factor Analysis (PARAFAC) identified a protein-like DOM fluorescent component as well as several other components associated with terrestrial plant material. Correlation analysis between the protein-like DOM component and hydrologic patterns, SUVA , and DOC concentrations suggest that DOM during dry seasons represents more microbially-processed sources, such as protein-rich, deeper soil or DOM with greater in-stream microbial processing, compared to more plant-like surface soil sources observed during high flow. The base flow index (the proportion of base flow to total flow) showed a high correlation with the relative proportion of protein-like DOM indicating that deep soil water is a source of the protein-like signal. The relative proportions of the protein-like DOM and humic DOM were also influenced by the abundance of coarse woody debris (CWD), but not live tree biomass, with the proportions of protein-like DOM highest in harvested watersheds with low surficial CWD. This study shows UV and fluorescent spectroscopy is a viable finger printing method to elucidate DOM sources in pristine headwater streams at the western Cascades of Oregon.
    Keywords: DOM ; Fluorescent ; Parafac ; Eem ; Hydrology ; Doc ; Forestry ; Biology
    ISSN: 0378-1127
    E-ISSN: 1872-7042
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  • 3
    Language: English
    In: Biogeochemistry, Dec, 2010, Vol.101(1-3), p.1(3)
    Description: Byline: Kate Lajtha (1), Philippe C. Baveye (2,3) Author Affiliation: (1) Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA (2) SIMBIOS Centre, Abertay University, 40 Bell Street, Dundee, DD1 1HG, UK (3) Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA Article History: Registration Date: 20/09/2010 Online Date: 10/10/2010
    Keywords: Biology ; Geology ; Chemistry;
    ISSN: 0168-2563
    E-ISSN: 1573515X
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  • 4
    Language: English
    In: Plant and Soil, 2013, Vol.367(1), pp.579-589
    Keywords: Litter fall manipulation ; Lignin degradation ; Fungi-to-bacteria ratio ; Temperate forest ; Field experiment
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 5
    Language: English
    In: Science of the Total Environment, 01 November 2018, Vol.640-641, pp.1112-1120
    Description: Ecological research networks functioning across climatic and edaphic gradients are critical for improving predictive understanding of biogeochemical cycles at local through global scales. One international network, the Detrital Input and Removal Treatment (DIRT) Project, was established to assess how rates and sources of plant litter inputs influence accumulations or losses of organic matter in forest soils. DIRT employs chronic additions and exclusions of aboveground litter inputs and exclusion of root ingrowth to permanent plots at eight forested and two shrub/grass sites to investigate how soil organic matter (SOM) dynamics are influenced by plant detrital inputs across ecosystem and soil types. Across the DIRT network described here, SOM pools responded only slightly, or not at all, to chronic doubling of aboveground litter inputs. Explanations for the slow or even negative response of SOM to litter additions include increased decomposition of new inputs and priming of old SOM. Evidence of priming includes increased soil respiration in litter addition plots, decreased dissolved organic carbon (DOC) output from increased microbial activity, and biochemical markers in soil indicating enhanced SOM degradation. SOM pools decreased in response to chronic exclusion of aboveground litter, which had a greater effect on soil C than did excluding roots, providing evidence that root-derived C is not more critical than aboveground litter C to soil C sequestration. Partitioning of belowground contributions to total soil respiration were predictable based on site-level soil C and N as estimates of site fertility; contributions to soil respiration from root respiration were negatively related to soil fertility and inversely, contributions from decomposing aboveground litter in soil were positively related to site fertility. The commonality of approaches and manipulations across the DIRT network has provided greater insights into soil C cycling than could have been revealed at a single site.
    Keywords: Soil Organic Matter ; Som ; Soil Carbon ; Litter ; Dirt ; Respiration ; Priming ; Density Fractionation ; Detritus ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 6
    Language: English
    In: Soil Biology and Biochemistry, March, 2014, Vol.70, p.237(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2013.12.028 Byline: Zsolt Kotroczo, Zsuzsa Veres, Istvan Fekete, Zsolt Krakomperger, Janos Attila Toth, Kate Lajtha, Bela Tothmeresz Abstract: Enzymes are considered to be a key soil component catalysing important transformations related to decomposition and nutrient turnover, and their activity in soil can be used as a measure of soil health. As part of the SikfAkut DIRT (Detritus Input and Removal Treatments) Project in a temperate deciduous forest in northern Hungary, we examined the extent to which enzyme activity in soil is influenced by both the quality and quantity of plant detrital inputs. DIRT treatments include doubling of leaf litter and woody debris inputs as well as removal of litter and trenching to prevent root inputs. Our objective was to examine seasonal dynamics of soil phosphatase and [beta]-glucosidase activities and to determine the effects of detrital manipulations on these dynamics. We found that the litter additions did not affect enzyme activities, but removal of roots caused significant decreases in enzyme activities. We conclude that plant-induced changes to soil enzyme activities are driven primarily by readily available, labile carbon provided by root turnover and root exudation rather than by aboveground detrital inputs. However, these results could also have been affected by changes in soil chemistry with detrital input removal: after only 6 years of litter removal, soil cation content decreased and soils became more acidic, both of which could inhibit enzyme activity. The soil phosphatase and [beta]-glucosidase enzymes measured showed similar seasonal dynamics. Both enzymes showed the highest activities in spring coincident with high soil moisture and, presumably, high root activity. The minimal response of soil enzyme activity to dramatic litter additions suggests a level of resilience in ecosystem function in this forest, and suggests that aboveground litter is not a significant source of labile carbon to microbes in the mineral soil. Author Affiliation: (a) Debrecen University, Department of Ecology, H-4032 Debrecen, Egyetem ter 1, Hungary (b) College of Nyiregyhaza, Institute of Environmental Sciences, H-4400 Nyiregyhaza, Sostoi ut 31, Hungary (c) Oregon State University, Department of Crop and Soil Science, 3017 Agricultural and Life Sciences Building, Corvallis, OR 97331, USA (d) MTA-DE Biodiversity and Ecosystem Services Research Group, Debrecen H-4010, P.O. Box 71, Hungary Article History: Received 24 January 2013; Revised 23 December 2013; Accepted 27 December 2013
    Keywords: Soil Moisture ; Enzymes ; Soil Microbiology ; Soil Chemistry ; Waste Disposal ; Enzymology ; Deciduous Forests ; Ecosystems
    ISSN: 0038-0717
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Plant and Soil, 2016, Vol.408(1), pp.133-148
    Description: Aims Characterizing the relationship between plant detrital inputs and the resulting dissolved organic carbon (DOC) leachate is vital to understanding the ultimate fate of root carbon, fallen wood and needles in forested watersheds. Similarly, elucidating chemical differences in the soil DOC pool may help to explain which DOC fractions are sorbed to mineral surfaces and contribute to accumulation of soil organic carbon, are respired as CO.sub.2, or are exported to nearby catchments. Methods In order to test the hypothesis that soils with different detrital inputs impart a detectable signal on DOC in mineral soil, soil solution DOC was sampled from the Detrital Input and Removal Treatment (DIRT) plots located in the H.J. Andrews Experimental Forest, OR. Multiple types of fresh litter extracts, along with lysimeter and soil extracts from DIRT treatment plots were characterized using UV-Vis and fluorescence spectroscopy coupled with the Cory and McKnight (Environ Sci Technol 39:8142-8149, 2005 (See CR6)) parallel factor analysis (PARAFAC) model. Results Principal component analysis of 13 unique fluorophores distinguished using PARAFAC show that litter and soil extracts (Douglas-fir needles, wood of decomposition Class 2, Class 3 and Class 5, O-horizon, and 0-5 cm A-horizon) each have distinct fluorescence signatures. However, while litter-leached DOC chemistry varies by litter type, neither lysimeter-collected DOC or soil extracts in the DIRT plots show statistically significant differences in fluorescence signatures among treatments, even after 17 years of litter manipulations. The lack of observed differences among DIRT treatments suggests that both abiotic interactions and microbial activity effectively homogenize organic carbon constituents within the dissolved pool. Minor but observable changes in PARAFAC components and optical indices during a 1-month biodegradation incubation of litter and soil extracts indicate that while biodegradation significantly alters DOC chemistry, abiotic mechanisms are also critical to DOC transformation in these soils with high sorption capacity. Conclusions Although leachates from different plant detrital sources have distinct carbon chemical signatures, these DOC signatures are effectively homogenized after passage through mineral soil. These results highlight the dominant role of both biotic and abiotic interactions in controlling the chemistry of DOC in shallow soils.
    Keywords: Dissolved organic carbon ; Soil organic matter ; Biodegradation ; Fluorescence ; PARAFAC
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 8
    Article
    Article
    Language: English
    In: Biogeochemistry, 2017, Vol.133(1), pp.1-1
    Keywords: Biology ; Geology ; Chemistry;
    ISSN: 0168-2563
    E-ISSN: 1573-515X
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  • 9
    Article
    Article
    Language: English
    In: Biogeochemistry, 2017, Vol.133(1), pp.3-5
    Description: Recent events in the U.S. have spurred us (the undersigned editors of Biogeochemistry) to make this statement in support of science and, in particular, environmental science. Media attention over “alternative facts” and “truthful hyperbole,” not to mention the tenor of the discussion over climate change, suggests that the very nature of science and its role in American society is under attack. We believe that well-established scientific consensus in these areas is being ignored in policy-making, and funding for scientific inquiry that runs counter to political interests is under threat. This political stance favoring ignorance over inquiry fundamentally would, if it is allowed to perpetuate, threaten not only our quality of life but also our future as a species.
    Keywords: Biology ; Geology ; Chemistry;
    ISSN: 0168-2563
    E-ISSN: 1573-515X
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  • 10
    Language: English
    In: Applied and Environmental Microbiology, Feb 15, 2013, Vol.79(4), pp.1385-1392
    Description: The article describes the study which tested the hypothesis that in soils lacking fresh root or detrital inputs, microbial community composition may persist relatively unchanged for long periods of time. The results indicate that even after 12 years of plant litter exclusion, community composition is well protected against a dramatic disturbance, thus supporting the hypothesis.
    Keywords: Litter (Trash) – Influence ; Microbial Colonies – Research ; Soil Microbiology – Research
    ISSN: 0099-2240
    Source: Cengage Learning, Inc.
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