TB105: The Composition of Equilibrium Soil Solutions from Forest Soil B Horizons

The objective of the present study was to evaluate the composition of B horizon equilibrium soil solutions from selected Maine forest soils. The B horizon was chosen for evaluation because it (1) best expressed the weathering processes active in the soil, (2) occupied the greatest volume of the solum, (3) had the most complex chemistry of the major horizons, and (4) provided the major corridor in forested ecosystems for subsurface flow and chemical alteration of ground waters.https://digitalcommons.library.umaine.edu/aes_techbulletin/1089/thumbnail.jp

TB118: Composition of Precipitation at the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) Site in Greenville, Maine

This report presents results of the analyses of samples collected at the Greenville, Maine, NADP station. The Greenville NADP/NTN station is in Piscataquis County at longitude 69°39\u2752 and latitude 4S°29\u2723 at approximately 322 meters elevation.https://digitalcommons.library.umaine.edu/aes_techbulletin/1078/thumbnail.jp

LTREB: Forest Ecosystem Response to Changes in Atmospheric Chemistry and Climate at the Bear Brook Watershed in Maine (BBWM)

The Bear Brook Watershed in Maine (BBWM) is a long-term paired, forested watershed research site with each watershed drained by a first order stream through a v-notch weir. One watershed (West Bear) has been treated bimonthly for 12 years with N and S by aerial helicopter applications, with the second watershed (East Bear) serving as the reference watershed. The objectives of this LTREB proposal are to: 1. Study the response of the calibrated East Bear Watershed to long-term patterns of ambient S, N, and base cation deposition. This will be accomplished by maintaining high quality deposition and stream export data from the reference watershed in support of research on ecosystem processes and change over time funded by this project and others. 2. Study the temporal progression of N saturation at the West Bear Watershed. This will be accomplished by continuing the decadal-scale whole ecosystem N & S addition experiment ongoing at the West Bear Watershed. 3. Determine if a definable relationship exists between short and longer-term climate and the biogeochemical and hydrologic processes currently under study at both watersheds. This will be accomplished by establishing an air and soil temperature measurement program across major ecosystem compartments at BBWM. Studies will focus on the relationships between temperature, N dynamics (mineralization, nitrification), and surface water N export in both the reference and treated watersheds, and we will evaluate the efficacy of using heat units to predict ecosystem behavior with respect to these processes. 4. Provide support to strengthen the data management efforts at the BBWM, thereby making this long-term record more accessible to the scientific community with an interpretive interface to be used by educators and policy makers through an expansive web presence. A major emphasis of this LTREB proposal is the development of a layered web presence on the BBWM project that provides access to data and highlights for policy makers, educators and researchers. 5. Provide support for graduate student training and undergraduate student experiences in research. Findings from this research have proven to be turnkey to date in regional and national debates on the effects of acid deposition and the risk of N saturation to forests and surface waters of New England. The compelling justification for supporting the long-term program of research at BBWM is that changes in response to changing ambient deposition of N and S (East Bear), long-term chemical manipulations (West Bear), and seasonal and inter-annual climate variation after 11+ years are showing mechanisms of response that were not discernable within the first 2-3 years of the study. These long-term mechanisms of response are frequently overlooked when research is conducted on short-term funding cycles. The long-term and unique responses being investigated at BBWM will be critical for adequately assessing policy and management options regarding air pollution and climate change in the 21st century

Scattering in Multilayered Structures: Diffraction from a Nanohole

The spectral expansion of the Green's tensor for a planar multilayered structure allows us to semi analytically obtain the angular spectrum representation of the field scattered by an arbitrary dielectric perturbation present in the structure. In this paper we present a method to find the expansion coefficients of the scattered field, given that the electric field inside the perturbation is available. The method uses a complete set of orthogonal vector wave functions to solve the structure's vector wave equation. In the two semi-infinite bottom and top media, those vector wave functions coincide with the plane-wave basis vectors, including both propagating and evanescent components. The technique is used to obtain the complete angular spectrum of the field scattered by a nanohole in a metallic film under Gaussian illumination. We also show how the obtained formalism can easily be extended to spherically and cylindrically multilayered media. In those cases, the expansion coefficients would multiply the spherical and cylindrical vector wave functions.Comment: 9 pages, 5 figure

Beryllium Biochemistry in a Forested Ecosystem

High rates of atmospheric deposition of beryllium are toxic biologically and are exacerbated by synergistic interaction with aluminum. The Czech Republic is experiencing growing problems, and similar consequences may well soon be experienced in Maine. An expert international research team would pursue parallel pilot studies into the biogeochemical controls on Be fate and transport by examining beryllium biogeochemistry in forested ecosystems. This project funds the work in Maine and travel for international collaboration; the Czechs are supporting the work in their country. The plan for the pilot study is to develop chemical time series for beryllium fluxes into, through, and out of watersheds in a paired study in the Bear Brook Watershed where one watersheds is being artificially acidified with ammonium sulfate. The study evaluates the fluxes of total BE and 7Be at the forest floor, leaving the watersheds, and in litter fall. Be in stream vegetation and sediment is being evaluated before and after acidic discharge events to assess temporary exchangeable pools

Collaborative Research: Interactive Effects of Chronic N deposition, Acidification, and Phosphorus Limitation on Coupled Element Cycling in Streams

The overarching goal of this project is to understand how chronic acidification and nitrogen enrichment of watersheds influences coupled biogeochemical cycling in streams. Embedded in the project were two primary research elements: 1) examining nitrogen satuartion and the extent of coupling between nitrogen and phosphorus cycling and 2) resolving the interactions among acidification, phosphorus bioavailability and biotic demand for nitrogen and phosphorus. The research involved a series of stable isotope tracer experiments to document nitrogen uptake under ambient and elevated phosphrous conditions and examination of a suite of key microbial processes (denitrification, decomposition, microbial enzyme activity) at two whole-watershed experiment sites. A microcosm experiment was used to examine the influence of acidity stress on animal and microbial stoichiometry

LTREB: Biogeochemical Mechanisms of Response in the Third Decade of Whole-Ecosystem Experimental Manipulations at the Bear Brook Watershed in Maine (BBWM)

This grant will support the Bear Brook Watershed in Maine (BBWM) where research has been conducted for approximately 20 years on the effects of atmospheric sulfur and nitrogen deposition on forests. The research is conducted on two watersheds, each drained by a first order stream. One is treated bimonthly by helicopter to simulate atmospheric deposition of sulfur and nitrogen. Over the past 20 years, this research has identified and verified key factors governing forest response to air pollution, and also revealed major gaps in our understanding that are critical to determining the success of current and potential future regulations under the Clean Air Act and its amendments of 1990. Recent research is also studying how climate interacts with other air pollutants to determine water quality and forest health. This grant will support the project into the third decade where new ecological response mechanisms are emerging that can only be investigated by long-term, multi-decadal research.The broader impacts of this project include the training of undergraduate and graduate students who will be the scientific leaders of tomorrow. This research provides direct evidence of whole-ecosystem responses to chemical treatments that simulate air pollutants providing results not possible from controlled laboratory studies. The issue of acid deposition remains a concern for forest ecosystem health and water quality. There are also direct interactions between climate and acid deposition that few field research sites in the world are prepared to study. This research directly addresses those information needs for today and the future

Impacts and Risk of Generative AI Technology on Cyber Defense

Generative Artificial Intelligence (GenAI) has emerged as a powerful technology capable of autonomously producing highly realistic content in various domains, such as text, images, audio, and videos. With its potential for positive applications in creative arts, content generation, virtual assistants, and data synthesis, GenAI has garnered significant attention and adoption. However, the increasing adoption of GenAI raises concerns about its potential misuse for crafting convincing phishing emails, generating disinformation through deepfake videos, and spreading misinformation via authentic-looking social media posts, posing a new set of challenges and risks in the realm of cybersecurity. To combat the threats posed by GenAI, we propose leveraging the Cyber Kill Chain (CKC) to understand the lifecycle of cyberattacks, as a foundational model for cyber defense. This paper aims to provide a comprehensive analysis of the risk areas introduced by the offensive use of GenAI techniques in each phase of the CKC framework. We also analyze the strategies employed by threat actors and examine their utilization throughout different phases of the CKC, highlighting the implications for cyber defense. Additionally, we propose GenAI-enabled defense strategies that are both attack-aware and adaptive. These strategies encompass various techniques such as detection, deception, and adversarial training, among others, aiming to effectively mitigate the risks posed by GenAI-induced cyber threats

Does Elevated Nitrogen and Sulfur Deposition Lead to Net Base Cation Losses in Northern New England Forest Soils?

The aims of this research are to continue treatment and monitoring of a paired watershed experiment at Bear Brook in northern Maine, with an emphasis on changes in soil base cations, particularly calcium. Base cation depletion is well-recognised as a potential problem in soils that have been subjected to acidic N deposition but few data exist from well-controlled, long-term experiments. The Bear Brook watershed has been periodically treated with ammonium sulfate since the fall of 1989 and is believed to be approaching N saturation. Since 1993 the relationship between base cations and strong acid anions has changed, such that labile Ca and Mg may be depleted in the soils as Al losses increase. Continued monitoring will allow tests of a series of hypotheses about controls and mechanisms of cation retention and leaching in temperate forest soils

TB178: Methods for Evaluating Carbon Fractions in Forest Soils: A Review

This publication was developed as part of an effort to evaluate the existing methodologies for determining carbon fractions in soils that might be applied to the question of forest soil C sequestration. A great deal of research has been done on this topic although often focused on agronomic soils. Forest land managers will be increasingly interested in identifying methods to monitor and to evaluate the effects of forest practices on soil C reserves. As well researchers are interested in this and the logical linkages to N cycling. Ultimately practical methods that can be widely utilized will be needed; these may come from current methods or be developed through research. This review offers a framework for this area of investigation.https://digitalcommons.library.umaine.edu/aes_techbulletin/1030/thumbnail.jp