Orbital changes, variation in solar activity and increased anthropogenic activities: controls on the Holocene flood frequency in the Lake Ledro area, Northern Italy

Adding to the on-going debate regarding vegetation recolonisation (more particularly the timing) in Europe and climate change since the Lateglacial, this study investigates a long sediment core (LL081) from Lake Ledro (652ma.s.l., southern Alps, Italy). Environmental changes were reconstructed using multiproxy analysis (pollen-based vegetation and climate reconstruction, lake levels, magnetic susceptibility and X-ray fluorescence (XRF) measurements) recorded climate and land-use changes during the Lateglacial and early-middle Holocene. The well-dated and high-resolution pollen record of Lake Ledro is compared with vegetation records from the southern and northern Alps to trace the history of tree species distribution. An altitudedependent progressive time delay of the first continuous occurrence of Abies (fir) and of the Larix (larch) development has been observed since the Lateglacial in the southern Alps. This pattern suggests that the mid-altitude Lake Ledro area was not a refuge and that trees originated from lowlands or hilly areas (e.g. Euganean Hills) in northern Italy. Preboreal oscillations (ca. 11 000 cal BP), Boreal oscillations (ca. 10 200, 9300 cal BP) and the 8.2 kyr cold event suggest a centennial-scale climate forcing in the studied area. Picea (spruce) expansion occurred preferentially around 10 200 and 8200 cal BP in the south-eastern Alps, and therefore reflects the long-lasting cumulative effects of successive boreal and the 8.2 kyr cold event. The extension of Abies is contemporaneous with the 8.2 kyr event, but its development in the southern Alps benefits from the wettest interval 8200-7300 cal BP evidenced in high lake levels, flood activity and pollen-based climate reconstructions. Since ca. 7500 cal BP, a weak signal of pollen-based anthropogenic activities suggest weak human impact. The period between ca. 5700 and ca. 4100 cal BP is considered as a transition period to colder and wetter conditions (particularly during summers) that favoured a dense beech (Fagus) forest development which in return caused a distinctive yew (Taxus) decline.We conclude that climate was the dominant factor controlling vegetation changes and erosion processes during the early and middle Holocene (up to ca. 4100 cal BP).

Negative responses of highland pines to anthropogenic activities in inland Spain: a palaeoecological perspective

Palaeoecological evidence indicates that highland pines were dominant in extensive areas of the mountains of Central and Northern Iberia during the first half of the Holocene. However, following several millennia of anthropogenic pressure, their natural ranges are now severely reduced. Although pines have been frequently viewed as first-stage successional species responding positively to human disturbance, some recent palaeobotanical work has proposed fire disturbance and human deforestation as the main drivers of this vegetation turnover. To assess the strength of the evidence for this hypothesis and to identify other possible explanations for this scenario, we review the available information on past vegetation change in the mountains of northern inland Iberia. We have chosen data from several sites that offer good chronological control, including palynological records with microscopic charcoal data and sites with plant macro- and megafossil occurrence. We conclude that although the available long-term data are still fragmentary and that new methods are needed for a better understanding of the ecological history of Iberia, fire events and human activities (probably modulated by climate) have triggered the pine demise at different locations and different temporal scales. In addition, all palaeoxylological, palynological and charcoal results obtained so far are fully compatible with a rapid human-induced ecological change that could have caused a range contraction of highland pines in western Iberia.

Impact of Late Holocene climate variability and anthropogenic activities on Biscayne Bay (Florida, U.S.A.): Evidence from diatoms

Shallow marine ecosystems are experiencing significant environmental alterations as a result of changing climate and increasing human activities along coasts. Intensive urbanization of the southeast Florida coast and intensification of climate change over the last few centuries changed the character of coastal ecosystems in the semi-enclosed Biscayne Bay, Florida. In order to develop management policies for the Bay, it is vital to obtain reliable scientific evidence of past ecological conditions. The long-term records of subfossil diatoms obtained from No Name Bank and Featherbed Bank in the Central Biscayne Bay, and from the Card Sound Bank in the neighboring Card Sound, were used to study the magnitude of the environmental change caused by climate variability and water management over the last ~ 600 yr. Analyses of these records revealed that the major shifts in the diatom assemblage structures at No Name Bank occurred in 1956, at Featherbed Bank in 1966, and at Card Sound Bank in 1957. Smaller magnitude shifts were also recorded at Featherbed Bank in 1893, 1942, 1974 and 1983. Most of these changes coincided with severe drought periods that developed during the cold phases of El Niño Southern Oscillation (ENSO), Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO), or when AMO was in warm phase and PDO was in the cold phase. Only the 1983 change coincided with an unusually wet period that developed during the warm phases of ENSO and PDO. Quantitative reconstructions of salinity using the weighted averaging partial least squares (WA-PLS) diatom-based salinity model revealed a gradual increase in salinity at the three coring locations over the last ~ 600 yr, which was primarily caused by continuously rising sea level and in the last several decades also by the reduction of the amount of freshwater inflow from the mainland. Concentration of sediment total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC) increased in the second half of the 20th century, which coincided with the construction of canals, landfills, marinas and water treatment plants along the western margin of Biscayne Bay. Increased magnitude and rate of the diatom assemblage restructuring in the mid- and late-1900s, suggest that large environmental changes are occurring more rapidly now than in the past.

Impact of Late Holocene Climate Variability and Anthropogenic Activities on Biscayne Bay (Florida, U.S.A.): Evidence From Diatoms

Shallow marine ecosystems are experiencing significant environmental alterations as a result of changing climate and increasing human activities along coasts. Intensive urbanization of the southeast Florida coast and intensification of climate change over the last few centuries changed the character of coastal ecosystems in the semi-enclosed Biscayne Bay, Florida. In order to develop management policies for the Bay, it is vital to obtain reliable scientific evidence of past ecological conditions. The long-term records of subfossil diatoms obtained from No Name Bank and Featherbed Bank in the Central Biscayne Bay, and from the Card Sound Bank in the neighboring Card Sound, were used to study the magnitude of the environmental change caused by climate variability and water management over the last ~ 600 yr. Analyses of these records revealed that the major shifts in the diatom assemblage structures at No Name Bank occurred in 1956, at Featherbed Bank in 1966, and at Card Sound Bank in 1957. Smaller magnitude shifts were also recorded at Featherbed Bank in 1893, 1942, 1974 and 1983. Most of these changes coincided with severe drought periods that developed during the cold phases of El Niño Southern Oscillation (ENSO), Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO), or when AMO was in warm phase and PDO was in the cold phase. Only the 1983 change coincided with an unusually wet period that developed during the warm phases of ENSO and PDO. Quantitative reconstructions of salinity using the weighted averaging partial least squares (WA-PLS) diatom-based salinity model revealed a gradual increase in salinity at the three coring locations over the last ~ 600 yr, which was primarily caused by continuously rising sea level and in the last several decades also by the reduction of the amount of freshwater inflow from the mainland. Concentration of sediment total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC) increased in the second half of the 20th century, which coincided with the construction of canals, landfills, marinas and water treatment plants along the western margin of Biscayne Bay. Increased magnitude and rate of the diatom assemblage restructuring in the mid- and late-1900s, suggest that large environmental changes are occurring more rapidly now than in the past.

Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

Anthropogenic disturbance as a driver of microspatial and microhabitat segregation of cytotypes of Centaurea stoebe and cytotype interactions in secondary contact zones.

BACKGROUND AND AIMS: In a mixed-ploidy population, strong frequency-dependent mating will lead to the elimination of the less common cytotype, unless prezygotic barriers enhance assortative mating. However, such barriers favouring cytotype coexistence have only rarely been explored. Here, an assessment is made of the mechanisms involved in formation of mixed-ploidy populations and coexistence of diploid plants and their closely related allotetraploid derivates from the Centaurea stoebe complex (Asteraceae). METHODS: An investigation was made of microspatial and microhabitat distribution, life-history and fitness traits, flowering phenology, genetic relatedness of cytotypes and intercytotype gene flow (cpDNA and microsatellites) in six mixed-ploidy populations in Central Europe. KEY RESULTS: Diploids and tetraploids were genetically differentiated, thus corroborating the secondary origin of contact zones. The cytotypes were spatially segregated at all sites studied, with tetraploids colonizing preferentially drier and open microhabitats created by human-induced disturbances. Conversely, they were rare in more natural microsites and microsites with denser vegetation despite their superior persistence ability (polycarpic life cycle). The seed set of tetraploid plants was strongly influenced by their frequency in mixed-ploidy populations. Triploid hybrids originated from bidirectional hybridizations were extremely rare and almost completely sterile, indicating a strong postzygotic barrier between cytotypes. CONCLUSIONS: The findings suggest that tetraploids are later immigrants into already established diploid populations and that anthropogenic activities creating open niches favouring propagule introductions were the major factor shaping the non-random distribution and habitat segregation of cytotypes at fine spatial scale. Establishment and spread of tetraploids was further facilitated by their superior persistence through the perennial life cycle. The results highlight the importance of non-adaptive spatio-temporal processes in explaining microhabitat and microspatial segregation of cytotypes.

Diversity of Somatic Coliphages in Coastal Regions with Different Levels of Anthropogenic Activity in Sao Paulo State, Brazil

Bacteriophages are the most abundant and genetically diverse viruses on Earth, with complex ecology in both quantitative and qualitative terms. Somatic coliphages (SC) have been reported to be good indicators of fecal pollution in seawater. This study focused on determining the concentration of SC and their diversity by electron microscopy of seawater, plankton, and bivalve samples collected at three coastal regions in Sao Paulo, Brazil. The SC counts varied from < 1 to 3.4 x 103 PFU/100 ml in seawater (73 samples tested), from < 1 to 4.7 x 10(2) PFU/g in plankton (46 samples tested), and from < 1 to 2.2 x 10(1) PFU/g in bivalves (11 samples tested). In seawater samples, a relationship between the thermotolerant coliforms and Escherichia coli and SC was observed at the three regions (P = 0.0001) according to the anthropogenic activities present at each region. However, SC were found in plankton samples from three regions: Baixada Santista (17/20), Canal de Sao Sebastiao (6/14), and Ubatuba (3/12). In seawater samples collected from Baixada Santista, four morphotypes were observed: A1 (4.5%), B1 (50%), C1 (36.4%), and D1 (9.1%). One coliphage, Siphoviridae type T1, had the longest tail: between 939 and 995 nm. In plankton samples, Siphoviridae (65.8%), Podoviridae (15.8%), Microviridae (15.8%), and Myoviridae (2.6%) were found. In bivalves, only the morphotype B1 was observed. These SC were associated with enteric hosts: enterobacteria, E. coli, Proteus, Salmonella, and Yersinia. Baixada Santista is an area containing a high level of fecal pollution compared to those in the Canal de Sao Sebastiao and Ubatuba. This is the first report of coliphage diversity in seawater, plankton, and bivalve samples collected from Sao Paulo coastal regions. A better characterization of SC diversity in coastal environments will help with the management and evaluation of the microbiological risks for recreation, seafood cultivation, and consumption.

Weathering rates and anthropogenic influences in a sedimentary basin, São Paulo State, Brazil

The weathering rate of rocks and chemical dynamics of the Corumbatai River basin, São Paulo State, Brazil, were evaluated using major elements as natural tracers. This basin has serious environmental problems in terms of quality of surface and rainwater, which affect the determination of weathering rate. The Corumbatai River, downstream from Rio Claro City, receives several elements/compounds through anthropogenic activities, with only K, SO42- and alkalinity yielding positive flux values. The negative flux of some anions/cations can be attributed to atmospheric loading mainly related to anthropogenic inputs, providing K a value of 16.7 ton/km(-2)a(-1) for the material removed by weathering in the Corumbatai River basin. This is equivalent to 26 x 10(6) kg of rock being removed each year by the Corumbatai River. The instantaneous flux was found to be a function of discharge, with the majority of dry residue (dissolved load) being transported during the summer (wet) months. The removed material in Corumbatai River basin derives mainly from two sub-basins (Cabegas River and Passa Cinco River), where the sandstones weather more easily than siltstones and claystones in the basin. (C) 2003 Elsevier Ltd. All rights reserved.

Anthropogenic influences on annual flux of cations and anions at meio stream basin, São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Hydrochemistry on a waste disposal area of sand mining activities at Analandia, Sao Paulo State, Brazil, and their implications on the mobilization of uranium

Groundwaters and surface waters from an area of treatment of sand for industrial purposes at Analandia municipality, nearly in the center of Sao Paulo State, Brazil, were chemically and isotopically analyzed with two aims: to evaluate if the anthropogenic activities that has taken place for the last 6 years is affecting the quality of the hydrological resources and to relate the hydrogeochemical behaviour of the uranium isotopes 234U and 238U with the pattern of circulation of groundwaters.

Anthropogenic influences on Cd, Cr,Cu, Ni, Pb and Zn concentrations in soils and sediments in a watershed with sugar cane crops at São Paulo State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anthropogenic impacts on mineral weathering: A statistical perspective

Correspondence Analysis was adopted as tool for investigating the statistical structure of hydrochemical and weathering datasets of groundwater samples, with the main purpose of identifying impacts on mineral weathering caused by anthropogenic activities, namely fertilizing of farmlands. The hydrochemical dataset comprised measured concentrations of major inorganic compounds dissolved in groundwater, namely bicarbonate, silica (usually by-products of chemical weathering), chloride, sulphate and nitrate (typically atmospheric plus anthropogenic inputs). The weathering dataset consisted of calculated mass transfers of minerals being dissolved in loess sediments of a region located in SW Hungary (Szigetvár area), namely Na-plagioclase, calcite and dolomite, and of pollution-related concentrations of sodium, magnesium and calcium. A first run of Correspondence Analysis described groundwater composition in the study area as a system of triple influence, where spots of domestic effluents-dominated chemistries are surrounded by areas with agriculture-dominated chemistries, both imprinted over large regions of weathering dominated chemistries. A second run revealed that nitrification of N-fertilizers is promoting mineral weathering by the nitric acid reaction (anthropogenic pathway), in concurrence with the retreating of weathering by carbonic acid (natural pathway). It also indicated that dolomite and calcite are being players in a dedolomitization process driven by dissolution of gypsum fertilizers and nitrification of N-fertilizers. © 2013 Elsevier Ltd.

Nitrogen Oxides in the North Atlantic Troposphere: Impacts of Boreal Wildfire and Anthropogenic Emissions

Nitrogen oxides play a crucial role in the budget of tropospheric ozone (O sub(3)) and the formation of the hydroxyl radical. Anthropogenic activities and boreal wildfires are large sources of emissions in the atmosphere. However, the influence of the transport of these emissions on nitrogen oxides and O sub(3) levels at hemispheric scales is not well understood, in particular due to a lack of nitrogen oxides measurements in remote regions. In order to address these deficiencies, measurements of NO, NO sub(2) and NO sub(y) (total reactive nitrogen oxides) were made in the lower free troposphere (FT) over the central North Atlantic region (Pico Mountain station, 38 degree N 28 degree W, 2.3 km asl) from July 2002 to August 2005. These measurements reveal a well-defined seasonal cycle of nitrogen oxides (NO sub(x) = NO+NO sub(2) and NO sub(y)) in the background central North Atlantic lower FT, with higher mixing ratios during the summertime. Observed NO sub(x) and NO sub(y) levels are consistent with long-range transport of emissions, but with significant removal en-route to the measurement site. Reactive nitrogen largely exists in the form of PAN and HNO sub(3) ( similar to 80-90% of NO sub(y)) all year round. A shift in the composition of NO sub(y) from dominance of PAN to dominance of HNO sub(3) occurs from winter-spring to summer-fall, as a result of changes in temperature and photochemistry over the region. Analysis of the long-range transport of boreal wildfire emissions on nitrogen oxides provides evidence of the very large-scale impacts of boreal wildfires on the tropospheric NO sub(x) and O sub(3) budgets. Boreal wildfire emissions are responsible for significant shifts in the nitrogen oxides distributions toward higher levels during the summer, with medians of NO sub(y) (117-175 pptv) and NO sub(x) (9-30 pptv) greater in the presence of boreal wildfire emissions. Extreme levels of NO sub(x) (up to 150 pptv) and NO sub(y) (up to 1100 pptv) observed in boreal wildfire plumes suggest that decomposition of PAN to NO sub(x) is a significant source of NO sub(x), and imply that O sub(3) formation occurs during transport. Ozone levels are also significantly enhanced in boreal wildfire plumes. However, a complex behavior of O sub(3) is observed in the plumes, which varies from significant to lower O sub(3) production to O sub(3) destruction. Long-range transport of anthropogenic emissions from North America also has a significant influence on the regional NO sub(x) and O sub(3) budgets. Transport of pollution from North America causes significant enhancements on nitrogen oxides year-round. Enhancements of CO, NO sub(y) and NO sub(x) indicate that, consistent with previous studies, more than 95% of the NO sub(x) emitted over the U.S. is removed before and during export out of the U.S. boundary layer. However, about 30% of the NO sub(x) emissions exported out of the U.S. boundary layer remain in the airmasses. Since the lifetime of NO sub(x) is shorter than the transport timescale, PAN decomposition and potentially photolysis of HNO sub(3) provide a supply of NO sub(x) over the central North Atlantic lower FT. Observed Delta O sub(3)/ Delta NO sub(y) and large NO sub(y) levels remaining in the North American plumes suggest potential O sub(3) formation well downwind from North America. Finally, a comparison of the nitrogen oxides measurements with results from the global chemical transport (GCT) model GEOS-Chem identifies differences between the observations and the model. GEOS-Chem reproduces the seasonal variation of nitrogen oxides over the central North Atlantic lower FT, but does not capture the magnitude of the cycles. Improvements in our understanding of nitrogen oxides chemistry in the remote FT and emission sources are necessary for the current GCT models to adequately estimate the impacts of emissions on tropospheric NO sub(x) and the resulting impacts on the O sub(3) budget.

INTEGRATED ASSESSMENT OF ANTHROPOGENIC, CLIMATE, AND POLICY INDUCED CHANGES OF PHOSPHORUS EXPORT IN THE UNITED STATES LAURENTIAN GREAT LAKES WATERSHEDS

Anthropogenic activities have increased phosphorus (P) loading in tributaries to the Laurentian Great Lakes resulting in eutrophication in small bays to most notably, Lake Erie. Changes to surface water quality from P loading have resulted in billions of dollars in damage and threaten the health of the world’s largest freshwater resource. To understand the factors affecting P delivery with projected increasing urban lands and biofuels expansion, two spatially explicit models were coupled. The coupled models predict that the majority of the basin will experience a significant increase in urban area P sources while the agriculture intensity and forest sources of P will decrease. Changes in P loading across the basin will be highly variable spatially. Additionally, the impacts of climate change on high precipitation events across the Great Lakes were examined. Using historical regression relationships on phosphorus concentrations, key Great Lakes tributaries were found to have future changes including decreasing total loads and increases to high-flow loading events. The urbanized Cuyahoga watersheds exhibits the most vulnerability to these climate-induced changes with increases in total loading and storm loading , while the forested Au Sable watershed exhibits greater resilience. Finally, the monitoring network currently in place for sampling the amount of phosphorus entering the U.S. Great Lakes was examined with a focus on the challenges to monitoring. Based on these interviews, the research identified three issues that policy makers interested in maintaining an effective phosphorus monitoring network in the Great Lakes should consider: first, that the policy objectives driving different monitoring programs vary, which results in different patterns of sampling design and frequency; second, that these differences complicate efforts to encourage collaboration; and third, that methods of funding sampling programs vary from agency to agency, further complicating efforts to generate sufficient long-term data to improve our understanding of phosphorus into the Great Lakes. The dissertation combines these three areas of research to present the potential future impacts of P loading in the Great Lakes as anthropogenic activities, climate and monitoring changes. These manuscripts report new experimental data for future sources, loading and climate impacts on phosphorus.