Showing papers by "University of New Hampshire published in 2003"

Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems

Abstract: Rates and reactions of biogeochemical processes vary in space and time to produce both hot spots and hot moments of elemental cycling. We define biogeochemical hot spots as patches that show disproportionately high reaction rates relative to the surrounding matrix, whereas hot moments are defined as short periods of time that exhibit disproportionately high reaction rates relative to longer intervening time periods. As has been appreciated by ecologists for decades, hot spot and hot moment activity is often enhanced at terrestrial-aquatic interfaces. Using examples from the carbon (C) and nitrogen (N) cycles, we show that hot spots occur where hydrological flowpaths converge with substrates or other flowpaths containing complementary or missing reactants. Hot moments occur when episodic hydrological flowpaths reactivate and/or mobilize accumulated reactants. By focusing on the delivery of specific missing reactants via hydrologic flowpaths, we can forge a better mechanistic understanding of the factors that create hot spots and hot moments. Such a mechanistic understanding is necessary so that biogeochemical hot spots can be identified at broader spatiotemporal scales and factored into quantitative models. We specifically recommend that resource managers incorporate both natural and artificially created biogeochemical hot spots into their plans for water quality management. Finally, we emphasize the needs for further research to assess the potential importance of hot spot and hot moment phenomena in the cycling of different bioactive elements, improve our ability to predict their occurrence, assess their importance in landscape biogeochemistry, and evaluate their utility as tools for resource management.

The Importance of Land-Use Legacies to Ecology and Conservation

Abstract: Recognition of the importance of land-use history and its legacies in most ecological systems has been a major factor driving the recent focus on human activity as a legitimate and essential subject of environmental science. Ecologists, conservationists, and natural resource policymakers now recognize that the legacies of land-use activities continue to influence ecosystem structure and function for decades or centuries—or even longer—after those activities have ceased. Consequently, recognition of these historical legacies adds explanatory power to our understanding of modern conditions at scales from organisms to the globe and reduces missteps in anticipating or managing for future conditions. As a result, environmental history emerges as an integral part of ecological science and conservation planning. By considering diverse ecological phenomena, ranging from biodiversity and biogeochemical cycles to ecosystem resilience to anthropogenic stress, and by examining terrestrial and aquatic ecosyst...

The Arabidopsis CDPK-SnRK Superfamily of Protein Kinases

Abstract: The CDPK-SnRK superfamily consists of seven types of serine-threonine protein kinases: calcium-dependent protein kinase (CDPKs), CDPK-related kinases (CRKs), phosphoenolpyruvate carboxylase kinases (PPCKs), PEP carboxylase kinase-related kinases (PEPRKs), calmodulin-dependent protein kinases (CaMKs), calcium and calmodulin-dependent protein kinases (CCaMKs), and SnRKs. Within this superfamily, individual isoforms and subfamilies contain distinct regulatory domains, subcellular targeting information, and substrate specificities. Our analysis of the Arabidopsis genome identified 34 CDPKs, eight CRKs, two PPCKs, two PEPRKs, and 38 SnRKs. No definitive examples were found for a CCaMK similar to those previously identified in lily (Lilium longiflorum) and tobacco (Nicotiana tabacum) or for a CaMK similar to those in animals or yeast. CDPKs are present in plants and a specific subgroup of protists, but CRKs, PPCKs, PEPRKs, and two of the SnRK subgroups have been found only in plants. CDPKs and at least one SnRK have been implicated in decoding calcium signals in Arabidopsis. Analysis of intron placements supports the hypothesis that CDPKs, CRKs, PPCKs and PEPRKs have a common evolutionary origin; however there are no conserved intron positions between these kinases and the SnRK subgroup. CDPKs and SnRKs are found on all five Arabidopsis chromosomes. The presence of closely related kinases in regions of the genome known to have arisen by genome duplication indicates that these kinases probably arose by divergence from common ancestors. The PlantsP database provides a resource of continuously updated information on protein kinases from Arabidopsis and other plants.

Sea breeze: Structure, forecasting, and impacts

Abstract: [1] The sea breeze system (SBS) occurs at coastal locations throughout the world and consists of many spatially and temporally nested phenomena. Cool marine air propagates inland when a cross-shore mesoscale (2–2000 km) pressure gradient is created by daytime differential heating. The circulation is also characterized by rising currents at the sea breeze front and diffuse sinking currents well out to sea and is usually closed by seaward flow aloft. Coastal impacts include relief from oppressive hot weather, development of thunderstorms, and changes in air quality. This paper provides a review of SBS research extending back 2500 years but focuses primarily on recent discoveries. We address SBS forcing mechanisms, structure and related phenomena, life cycle, forecasting, and impacts on air quality.

Nitrogen Pollution in the Northeastern United States: Sources, Effects, and Management Options

Abstract: The northeastern United States receives elevated inputs of anthropogenic nitrogen (N) largely from net imports of food and atmospheric deposition, with lesser inputs from fertilizer, net feed imports, and N fixation associated with leguminous crops. Ecological consequences of elevated N inputs to the Northeast include tropospheric ozone formation, ozone damage to plants, the alteration of forest N cycles, acidification of surface waters, and eutrophication in coastal waters. We used two models, PnET-BGC and WATERSN, to evaluate management strategies for reducing N inputs to forests and estuaries, respectively. Calculations with PnET-BGC suggest that aggressive reductions in N emissions alone will not result in marked improvements in the acid–base status of forest streams. WATERSN calculations showed that management scenarios targeting removal of N by wastewater treatment produce larger reductions in estuarine N loading than scenarios involving reductions in agricultural inputs or atmospheric emis...

The CEBAF large acceptance spectrometer (CLAS)

Abstract: The CEBAF large acceptance spectrometer (CLAS) is used to study photo- and electro-induced nuclear and hadronic reactions by providing efficient detection of neutral and charged particles over a good fraction of the full solid angle. A collaboration of about 30 institutions has designed, assembled, and commissioned CLAS in Hall B at the Thomas Jefferson National Accelerator Facility. The CLAS detector is based on a novel six-coil toroidal magnet which provides a largely azimuthal field distribution. Trajectory reconstruction using drift chambers results in a momentum resolution of 0.5% at forward angles. Cherenkov counters, time-of-flight scintillators, and electromagnetic calorimeters provide good particle identification. Fast triggering and high data-acquisition rates allow operation at a luminosity of 10 34 nucleon cm −2 s −1 . These capabilities are being used in a broad experimental program to study the structure and interactions of mesons, nucleons, and nuclei using polarized and unpolarized electron and photon beams and targets. This paper is a comprehensive and general description of the design, construction and performance of CLAS.

The stages of vertebrate evolutionary radiation

Abstract: Evolutionists and ecologists are motivated to understand the forces that generate and maintain biological diversity. In turn, attention has focused on the relative roles of natural and sexual selection in vertebrate groups that are considered to be exemplars of evolutionary radiation. Here, we argue that recent phylogenetic and population genetic evidence shows that seemingly different vertebrate radiations follow similar evolutionary trajectories. Groups diverge along axes of habitat, trophic morphology and communication, often in that order. Notably, clades proceed to different stages of the radiation process, with the endpoint being correlated with species richness. Divergence along axes one and two (habitat and trophic morphology, respectively) is likely to follow ecological selection models; diversification along axis three (communication) probably proceeds according to sexual selection models. We speculate that a paucity of genetic variation for means of signaling that are independent of fitness traits might be the most important constraint limiting the diversification of vertebrate groups. The stages of evolutionary radiation discussed here do not apply to all organisms, but might represent a common trend.

Directional selection has shaped the oral jaws of Lake Malawi cichlid fishes

Abstract: East African cichlid fishes represent one of the most striking examples of rapid and convergent evolutionary radiation among vertebrates. Models of ecological speciation would suggest that functional divergence in feeding morphology has contributed to the origin and maintenance of cichlid species diversity. However, definitive evidence for the action of natural selection has been missing. Here we use quantitative genetics to identify regions of the cichlid genome responsible for functionally important shape differences in the oral jaw apparatus. The consistent direction of effects for individual quantitative trait loci suggest that cichlid jaws and teeth evolved in response to strong, divergent selection. Moreover, several chromosomal regions contain a disproportionate number of quantitative trait loci, indicating a prominent role for pleiotropy or genetic linkage in the divergence of this character complex. Of particular interest are genomic intervals with concerted effects on both the length and height of the lower jaw. Coordinated changes in this area of the oral jaw apparatus are predicted to have direct consequences for the speed and strength of jaw movement. Taken together, our results imply that the rapid and replicative nature of cichlid trophic evolution is the result of directional selection on chromosomal packages that encode functionally linked aspects of the craniofacial skeleton.

Interannual variability in the peatland-atmosphere carbon dioxide exchange at an ombrotrophic bog

Abstract: This loss was equivalent to between 30 and 70% of the net CO2 uptake during the growing season. During the first 3 years of study, the bog was an annual sink for CO2 (260 g CO2 m 2 yr 1 ). In the fourth year, with the dry summer, however, annual NEE was only 34 g CO2 m 2 yr 1 , which is not significantly different from zero. We examined the performance of a peatland carbon simulator (PCARS) model against the tower measurements of NEE and derived ecosystem respiration (ER) and photosynthesis (PSN). PCARS ER and PSN were highly correlated with tower-derived fluxes, but the model consistently overestimated both ER and PSN, with slightly poorer comparisons in the dry year. As a result of both component fluxes being overestimated, PCARS simulated the tower NEE reasonably well. Simulated decomposition and autotrophic respiration contributed about equal proportions to ER. Shrubs accounted for the greatest proportion of PSN (85%); moss PSN declined to near zero during the summer period due to surface drying. INDEX TERMS: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 1615 Global Change: Biogeochemical processes (4805); 1890 Hydrology: Wetlands; KEYWORDS: peatland, bog, net ecosystem exchange, eddy covariance, carbon dioxide

Observation of an Exotic S = +1 Baryon in Exclusive Photoproduction from the Deuteron

Abstract: In an exclusive measurement of the reaction {gamma}d {yields} K{sup +} K{sup -} p n, a narrow peak that can be attributed to an exotic baryon with strangeness S = +1 is seen in the K{sup +}n invariant mass spectrum. The peak is at 1542 {+-} 5 MeV/c{sup 2} with a measured width of 21 MeV/c{sup 2} FWHM, equivalent to the experimental invariant mass resolution. The statistical significance of the peak is 5.3 {+-} 0.5 {sigma} for a Gaussian peak shape on top of a smooth background.

Iron isotope constraints on Fe cycling and mass balance in oxygenated Earth oceans

Abstract: The Fe isotope composition of Proterozoic to modern clastic sedimentary rocks and aerosols defines a range ind 56 Fe values that is only slightly more variable than the range of Fe isotope com- positions measured in terrestrial igneous rocks, indicating that chemical weathering, sedimentary transport, and diagenesis play only a minor role in producing Fe isotope variations in environ- ments where Fe redox conditions have been controlled by current levels of atmospheric oxygen. In contrast, the Fe isotope composi- tions of hot fluids ( .300 8C) from mid-ocean-ridge (MOR) spread- ing centers define a narrow range that is shifted to lower d 56 Fe values by 0.2‰-0.5‰ as compared to igneous rocks. These new data allow a conceptual model for the Fe isotope composition of the oxic oceans that predicts large ranges in Fe isotope composition under conditions of changing aerosol and MOR Fe fluxes, such as during periods of major worldwide glaciation.

Incorporating World Englishes in Teaching English as an International Language

Abstract: 0 The discussion of World Englishes in the applied linguistics profession for the most part accepts multiple varieties of English as legitimate and worthy of study even if legitimacy remains the object of inquiry (see Higgins's article in this issue). Consistent with the value applied linguists place on World Englishes, English is taught and learned in many countries because it is an-and arguably the-international language. English is seen by many in Japan, for example, as a means to open doors to parts of the world that are not accessible to them otherwise, and learners are fascinated by the increased international opportunities they believe the knowledge of English will bring to them (Matsuda, 2002, in press). The international scope of learners' English learning agenda should logically be matched by pedagogical approaches that teach English as an international language (EIL), in part through inclusion of varieties of World Englishes. However, examination of English language teaching (ELT) practices in Japan reveals that English is still being taught as an inner-circle language, based almost exclusively on American or British English, and textbooks with characters and cultural topics from the English-speaking countries of the inner circle (Iwata et al., 2002; Kiryu, Shibata, Tagaya, & Wada, 1999; Matsuda, 2002). Issues associated with teaching English as an inner-circle language versus EIL need to be clarified if concrete changes are to be brought about in the way English is portrayed, valued, and taught in expandingcircle countries where it is not the native language of the majority or an official language. In this commentary, I therefore draw on research conducted in Japan (Matsuda, 2002) to demonstrate ways in which current practices in ELT teach English as an inner-circle language, why this approach to ELT is not appropriate in view of the curricular goals and learners' needs, and how World Englishes can be incorporated to teach EIL.

The impact of complex trauma and depression on parenting: an exploration of mediating risk and protective factors.

Abstract: The current study examined (a) maternal depression as a mediator between mothers' complex trauma exposure and parenting difficulties and (b) protective factors within a sample of adult survivors of complex child and adult trauma. Participants were a sample of 152 women selected from 174 women interviewed in the third wave of a longitudinal study of a hospital sample of girls. The women in the current study represent a subsample that includes all participants who had given birth to a child. Measures included assessments of women's own trauma history and parenting outcomes. Higher rates of trauma exposure were related to decreased parenting satisfaction, reports of child neglect, use of physical punishment, and a history of protective service reports. These links were partially mediated by the relationship between trauma exposure and increased maternal depression. Exploratory analyses were also conducted to examine protective factors for fewer parenting problems within a further subsample of trauma survivors.

The Exposure of Youth to Unwanted Sexual Material on the Internet: A National Survey of Risk, Impact, and Prevention.

Abstract: This national survey of youth, ages 10 to 17, and their caretakers has several implications for the current debate about young people and Internet pornography. Twenty five percent of youth had unwanted exposure to sexual pictures on the Internet in the past year, challenging the prevalent assumption that the problem is primarily about young people motivated to actively seek out pornography. Most youth had no negative reactions to their unwanted exposure, but one quarter said they were very or extremely upset, suggesting a priority need for more research on and interventions directed toward such negative effects. The use of filtering and blocking software was associated with a modest reduction in unwanted exposure, suggesting that it may help but is far from foolproof. Various forms of parental supervision were not associated with any reduction in exposure. The authors urge that social scientific research be undertaken to inform this highly contentious public policy controversy.

Factors affecting ammonium uptake in streams – an inter‐biome perspective

Abstract: SUMMARY 1. The Lotic Intersite Nitrogen eXperiment (LINX) was a coordinated study of the relationships between North American biomes and factors governing ammonium uptake in streams. Our objective was to relate inter-biome variability of ammonium uptake to physical, chemical and biological processes. 2. Data were collected from 11 streams ranging from arctic to tropical and from desert to rainforest. Measurements at each site included physical, hydraulic and chemical characteristics, biological parameters, whole-stream metabolism and ammonium uptake. Ammonium uptake was measured by injection of 15 N-ammonium and downstream measurements of 15 N-ammonium concentration. 3. We found no general, statistically significant relationships that explained the variability in ammonium uptake among sites. However, this approach does not account for the multiple mechanisms of ammonium uptake in streams. When we estimated biological demand for inorganic nitrogen based on our measurements of in-stream metabolism, we found good correspondence between calculated nitrogen demand and measured assimilative nitrogen uptake.

Current sheet structure near magnetic X-line observed by Cluster

Abstract: [1] During the interval 0947–0951 UT on 1 October 2001, when Cluster was located at XGSM = −16.4 RE near ZGSM = 0 in the pre-midnight magnetotail, the Cluster barycenter crosses the neutral sheet four times. High speed proton flow, with reversal from tailward to Earthward, was detected during the crossings. Using a linear gradient/curl estimator technique we estimate current density and magnetic field curvature within the crossings. These observations exhibit the tailward passage of an X-line over the Cluster tetrahedron. These current sheet has a bifurcated structure in the regions of tailward and earthward flows and a flat and/or slightly bifurcated thin current sheet in between. A distinct quadrupolar Hall magnetic field component was observed.

Determinants of a sustainable competitive advantage due to an IT-enabled strategy

Abstract: Information technology (IT) has been asserted to be a source of sustainable competitive advantage. Empirical evidence has shown that IT can improve a company's performance and competitive position. We examine the factors that are believed to lead to a sustainable competitive advantage due to an IT-enabled strategy, and test these factors empirically. Our findings show that managerial IT skills are positively related to sustainability, and competitor's knowledge of competitive advantage is negatively related to sustainability. There was no support for technical IT skills or IT infrastructure as a source of sustainable competitive advantage.

2 – Sources, Production, and Regulation of Allochthonous Dissolved Organic Matter Inputs to Surface Waters

Abstract: Publisher Summary The objective of this chapter is to examine and synthesize the published literature with respect to the sources and production of terrestrially derived Dissolved Organic Carbon (DOC), its relationship with Dissolved Organic Nitrogen (DON), and the mechanistic controls on their export from terrestrial ecosystems to surface waters Allochthonous dissolved organic matter is a source of organic carbon, nitrogen, phosphorus, and sulfur to aquatic systems that is derived from the surrounding terrestrial ecosystem Dissolved Organic Matter (DOM) is produced as precipitation moves through the atmosphere, washes through vegetation, infiltrates the soil organic horizon, and percolates downward through mineral soil horizons Organic forms of carbon, nitrogen, sulfur, and phosphorus contribute to bulk DOM The contribution of mineral soil solution DOM to allochthonous inputs will depend on: (1) watershed slope, (2) depth of water table, (3) antecedent soil moisture, and (4) barriers to organic soil solution infiltration of the mineral soil Delivery of terrestrially derived DOC and DON to the surface waters depends on the balance between production and loss from solution, and the opportunity for hydrological transport Large fluxes of atlochthonous DOM to surface waters occur when there is a barrier precluding water infiltration of the soil column Saturated soils— such as wetlands and peatlands also tend to produce runoff with higher DOC concentrations

Reciprocal transfer of carbon and nitrogen by decomposer fungi at the soil–litter interface

Abstract: We have investigated whether decomposer fungi translocate litter-derived C into the underlying soil while simultaneously translocating soil-derived inorganic N up into the litter layer. We also located and quantified where the translocated C is deposited within the soil aggregate structure. When 13 C-labeled wheat straw was decomposed on the surface of soil amended with 15 N-labeled inorganic N, we found that C and N were reciprocally transferred by fungi, with a significant quantity (121–151 μg C g −1 whole soil) of litter-derived C being deposited into newly formed macroaggregates (>250 μm sized aggregates). Fungal inhibition reduced fungal biomass and the bidirectional C and N flux by approximately 50%. The amount of litter-derived C found in macroaggregates was positively correlated with litter-associated fungal biomass. This fungal-mediated litter-to-soil C transfer, which to our knowledge has not been demonstrated before for saprophytic fungi, may represent an important mechanism by which litter C enters the soil and becomes stabilized as soil organic matter within the macroaggregate structure.

Inorganic bromine in the marine boundary layer: a critical review

Abstract: . The cycling of inorganic bromine in the marine boundary layer (mbl) has received increased attention in recent years. Bromide, a constituent of sea water, is injected into the atmosphere in association with sea-salt aerosol by breaking waves on the ocean surface. Measurements reveal that supermicrometer sea-salt aerosol is substantially depleted in bromine (often exceeding 50%) relative to conservative tracers, whereas marine submicrometer aerosol is often enriched in bromine. Model calculations, laboratory studies, and field observations strongly suggest that the supermicrometer depletions reflect the chemical transformation of particulate bromide to reactive inorganic gases that influence the processing of ozone and other important constituents of marine air. Mechanisms for the submicrometer enrichments are not well understood. Currently available techniques cannot reliably quantify many Br containing compounds at ambient concentrations and, consequently, our understanding of inorganic Br cycling over the oceans and its global significance are uncertain. To provide a more coherent framework for future research, we have reviewed measurements in marine aerosol, the gas phase, and in rain. We also summarize sources and sinks, as well as model and laboratory studies of chemical transformations. The focus is on inorganic bromine over the open oceans outside the polar regions. The generation of sea-salt aerosol at the ocean surface is the major tropospheric source producing about 6.2 Tg/a of bromide. The transport of Br from continents (as mineral aerosol, and as products from biomass-burning and fossil-fuel combustion) can be of local importance. Transport of degradation products of long-lived Br containing compounds from the stratosphere and other sources contribute lesser amounts. Available evidence suggests that, following aerosol acidification, sea-salt bromide reacts to form Br2 and BrCl that volatilize to the gas phase and photolyze in daylight to produce atomic Br and Cl. Subsequent transformations can destroy tropospheric ozone, oxidize dimethylsulfide (DMS) and hydrocarbons in the gas phase and S(IV) in aerosol solutions, and thereby potentially influence climate. The diurnal cycle of gas-phase Br and the corresponding particulate Br deficits are correlated. Higher values of Br in the gas phase during daytime are consistent with expectations based on photochemistry. We expect that the importance of inorganic Br cycling will vary in the future as a function of both increasing acidification of the atmosphere (through anthropogenic emissions) and climate changes. The latter affects bromine cycling via meteorological factors including global wind fields (and the associated production of sea-salt aerosol), temperature, and relative humidity.

Validation of proton transfer reaction-mass spectrometry (PTR-MS) measurements of gas-phase organic compounds in the atmosphere during the New England Air Quality Study (NEAQS) in 2002

Abstract: [1] Organic compounds were measured by proton transfer reaction-mass spectrometry (PTR-MS) on board the National Oceanic and Atmospheric Administration's research ship Ronald H. Brown during the New England Air Quality Study (NEAQS) in July and August of 2002. PTR-MS has the potential to measure many important organic species with a fast time response, but its validity has not been proven sufficiently. The results obtained by PTR-MS during NEAQS were compared with those from (oxygenated) hydrocarbon measurements by gas chromatography/mass spectrometry (GC-MS), peroxyacyl nitrate measurements by gas chromatography/electron capture detection, and carboxylic acid measurements by mist chamber/ion chromatography. The PTR-MS and GC-MS data for methanol, acetonitrile, acetone, isoprene, benzene, and toluene agreed within the measurement uncertainties. The comparison for C 8 aromatics and acetaldehyde was less quantitative due to calibration inaccuracies. In addition, PTR-MS measured the sum of methyl vinyl ketone and methacrolein at 71 amu, the sum of C9 aromatics at 121 amu, and the sum of monoterpenes at 81 and 137 amu. The PTR-MS signal at 61 amu was found to correlate well with data for acetic acid. The signal at 73 amu correlated reasonably well with methyl ethyl ketone data, but the quantitative disagreement suggested interference from other species, possibly methyl glyoxal. The signal at 77 amu correlated well with data for peroxyacetyl nitrate, and the sensitivity inferred from the field data agreed within 30% with the results from laboratory calibrations. Finally, the signal at 105 amu was attributed to styrene and peroxy isobutyryl nitrate. These results prove that many important organic species can be measured accurately and with a fast response time by PTR-MS.