992 resultados para environmental concentrations


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We examined the consequences of the spatial heterogeneity of atmospheric ammonia (NH3) by measuring and modelling NH3 concentrations and deposition at 25 m grid resolution for a rural landscape containing intensive poultry farming, agricultural grassland, woodland and moorland. The emission pattern gave rise to a high spatial variability of modelled mean annual NH3 concentrations and dry deposition. Largest impacts were predicted for woodland patches located within the agricultural area, while larger moorland areas were at low risk, due to atmospheric dispersion, prevailing wind direction and low NH3 background. These high resolution spatial details are lost in national scale estimates at 1 km resolution due to less detailed emission input maps. The results demonstrate how the spatial arrangement of sources and sinks is critical to defining the NH3 risk to semi-natural ecosystems. These spatial relationships provide the foundation for local spatial planning approaches to reduce environmental impacts of atmospheric NH3.

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The lipid content of three cores from Lake Enol (Picos de Europa National Park, Asturias, Northern Spain) was studied. The n-alkane profiles indicated a major input from terrigenous plants [predominance of high molecular weight (HMW) alkanes] since ca. 1695 AD to the water body, although the uppermost cm revealed a predominance of organic matter (OM) derived from algae, as the most abundant alkane was C17. Three units revealing different environmental conditions were defined. Unit A (ca. 1695–1860 AD) in the lowermost parts of ENO13-10 (< 12 cm) and ENO13-15 (< 28 cm) was identified and was characterized by higher OM input and evidence of minimal degradation (high CPI values, predominance of HMW n-alkanoic acids and good correspondence between the predominant n-alkane and n-alkanoic acid chains). These findings could be linked to the Little Ice Age, when cold and humid conditions may have favored an increase in total organic carbon (TOC) and n-alkane and n-alkanoic acid content (greater terrigenous OM in-wash), and may have also reduced bacterial activity. In Unit B (ca. 1860–1980 AD) the lack of correspondence between the n-alkane and n-alkanoic acid profiles of ENO13-10 (12–4 cm) and ENO13-15 (28–8 cm) suggested a certain preferential microbial synthesis of long chain saturated fatty acids from primary OM and/or bacterial activity, coinciding with a decrease in OM input, which could be linked to the global warming that started in the second half of the 19th century. In ENO13-7 the low OM input (low TOC) was accompanied by some bacterial degradation (predominance ofHMWn-alkanoic acids but with a bimodal distribution) in the lowermost 16–5 cm. Evidence of considerable phytoplankton productivity and microbial activity was especially significant in Unit C (ca. 1980–2013 AD) identified in the uppermost part of all three cores (5 cm in ENO13-7, 4 cm in ENO13-10 and 8 cm in ENO13-15), coinciding with higher concentrations of n-alkanes and n-alkanoic acids, which were considered to be linked to warmer and drier conditions, as well as to greater anthropogenic influence in modern times. Plant sterols, such as b-sitosterol, campesterol and stigmasterol, were significantly present in the cores. In addition, fecal stanols, such as 24-ethylcoprostanol from herbivores, were present, thereby indicating a continuous and significant pollution input derived from these animals since the 17th century, being more important in the last 20 years.

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The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as −3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter. Copious quantities of soluble metal sulfate salts such as melanterite, chalcanthite, coquimbite, rhomboclase, voltaite, copiapite, and halotrichite have been identified, and some of these are forming from negative-pH mine waters. Geochemical calculations show that, under a mine-plugging remediation scenario, these salts would dissolve and the resultant 600,000-m3 mine pool would have a pH of 1 or less and contain several grams of dissolved metals per liter, much like the current portal effluent water. In the absence of plugging or other at-source control, current weathering rates indicate that the portal effluent will continue for approximately 3,000 years. Other remedial actions have greatly reduced metal loads into downstream drainages and the Sacramento River, primarily by capturing the major acidic discharges and routing them to a lime neutralization plant. Incorporation of geochemical modeling and mineralogical expertise into the decision-making process for remediation can save time, save money, and reduce the likelihood of deleterious consequences.

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L-ascorbic acid (vitamin C) is a powerful reducing agent found in millimolar concentrations in plants, and is proposed to play an important role in scavenging free radicals in plants and animals. However, surprisingly little is known about the role of this antioxidant in plant environmental stress adaptation or ascorbate biosynthesis. We report the isolation of soz1, a semi-dominant ozone-sensitive mutant that accumulates only 30% of the normal ascorbate concentration. The results of genetic approaches and feeding studies show that the ascorbate concentration affects foliar resistance to the oxidizing gas ozone. Consistent with the proposed role for ascorbate in reactive oxygen species detoxification, lipid peroxides are elevated in soz1, but not in wild type following ozone fumigation. We show that the soz1 mutant is hypersensitive to both sulfur dioxide and ultraviolet B irradiation, thus implicating ascorbate in defense against varied environmental stresses. In addition to defining the first ascorbate deficient mutant in plants, these results indicate that screening for ozone-sensitive mutants is a powerful method for identifying physiologically important antioxidant mechanisms and signal transduction pathways. Analysis of soz1 should lead to more information about the physiological roles and metabolism of ascorbate.

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The purpose of this research was to apply the use of direct ablation plasma spectroscopic techniques, including spark-induced breakdown spectroscopy (SIBS) and laser-induced breakdown spectroscopy (LIBS), to a variety of environmental matrices. These were applied to two different analytical problems. SIBS instrumentation was adapted in order to develop a fieldable monitor for the measurement of carbon in soil. SIBS spectra in the 200 nm to 400 nm region of several soils were collected, and the neutral carbon line (247.85 nm) was compared to total carbon concentration determined by standard dry combustion analysis. Additionally, Fe and Si were evaluated in a multivariate model in order to determine their impacts on the model's predictive power for total carbon concentrations. The results indicate that SIBS is a viable method to quantify total carbon levels in soils; obtaining a good correlation between measured and predicated carbon in soils. These results indicate that multivariate analysis can be used to construct a calibration model for SIBS soil spectra, and SIBS is a promising method for the determination of total soil carbon. SIBS was also applied to the study of biological warfare agent simulants. Elemental compositions (determined independently) of bioaerosol samples were compared to the SIBS atomic (Ca, Al, Fe and Si) and molecular (CN, N2 and OH) emission signals. Results indicate a linear relationship between the temporally integrated emission strength and the concentration of the associated element. Finally, LIBS signals of hematite were analyzed under low pressures of pure CO2 and compared with signals acquired with a mixture of CO2, N2 and Ar, which is representative of the Martian atmosphere. This research was in response to the potential use of LIBS instrumentation on the Martian surface and to the challenges associated with these measurements. Changes in Ca, Fe and Al lineshapes observed in the LIBS spectra at different gas compositions and pressures were studied. It was observed that the size of the plasma formed on the hematite changed in a non-linear way as a function of decreasing pressure in a CO2 atmosphere and a simulated Martian atmosphere.

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Introduction The strong expansion of the world production of plastics caused a severe accumulation of plastic debris in the environment, which makes them one of the most important contaminants, growing as a global environmental problem. Although the production in Europe has been relatively constant in the last 10 years, world plastic production continues to increase, affecting soil biota and their functions. Objectives Thus, in order to evaluate the effects of MP in soil-dwelling organisms, earthworms (Eisenia andrei Bouché), were exposed to standard artificial soil mixed with MPs and the authors documented, using microscopic figures, the pathological lesions found in this biological model. Material and Methods Eight adult earthworms extracted from soils contaminated with different concentrations of MP (mg/kgdw) with sizes ranging between 250-1000 m, were fixed in 10% neutral-buffered formalin and processed for routine histopathological diagnosis. Results and discussion Contrary to what would be expected, MP were not found throughout the GI tube of earthworms but several lesions were found in the individuals extracted from the soils with high MP concentrations, when compared with control group, namely epithelial intestinal atrophy and evidences of inflammatory responses to this stress agent. Conclusion Earthworms have probably avoided the consumption of the biggest MPs. However, evidences point for lesions that were likely caused by the smallest MPs that were likely egested during the depuration phase.

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The present study investigates the concentrations and patterns of organochlorine pesticides (OCPs) and their metabolites in liver and plasma of two ringed seal populations (Phoca hispida): lower contaminated Svalbard population and more contaminated Baltic Sea population. Among OCPs, p,p'-DDE and sum-chlordanes were the highest in concentration. With increasing hepatic contaminant concentrations and activities of xenobiotic-metabolizing enzymes, the concentrations of 3-methylsulfonyl-p,p'-DDE and the concentration ratios of pentachlorophenol/hexachlorobenzene increased, and the toxaphene pattern shifted more towards persistent Parlar-26 and -50 and less towards more biodegradable Parlar-44. Relative concentrations of the chlordane metabolites, oxychlordane and -heptachlorepoxide, to sum-chlordanes were higher in the seals from Svalbard compared to the seals from the Baltic, while the trend was opposite for cis- and trans-nonachlor. The observed differences in the OCP patterns in the seals from the two populations are probably related to the catalytic activity of xenobiotic-metabolizing enzymes, and also to differences in dietary exposure.

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The flux of sediment and organic carbon from continents to the coastal ocean is an important factor governing organic burial in coastal sediments, and these systems preserve important records of environmental and biogeochemical conditions during past global change events. Burial of organic materials in coastal systems can be promoted by chemical resilience or through protection by association with mineral surfaces, but the role and influence of these processes on organic records from ancient sediments is poorly known. We studied sediment and organic matter burial as particulate organic matter (POM) and mineral-bound organic matter (MOM) in near-shore marine sediments from the Wilson Lake core (New Jersey, USA) that span the Paleocene-Eocene thermal maximum (PETM), a climatic perturbation 55.9 Myr ago. Our results show that distinct POM and MOM fractions can be isolated from sediments. Both fractions appear to be dominated by terrestrial material, but POM consisted primarily of recently synthesized material whereas MOM included a significant fraction of pre-aged organic matter from soils or ancient sediments. Variation in organic burial through the PETM is associated with changes in inorganic nitrogen burial, clay mineralogy, and clastic grain size that we associate with enhanced continental weathering, erosion and redeposition of ancient kaolinites, and eustatic sea level variation, respectively. These results provide a new perspective on factors governing carbon burial and carbon isotope records in ancient marine margin settings and offer information on rate and phasing of late Paleocene/early Eocene Earth system changes that may constrain interpretations of the cause of the PETM climate change event.

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The present data publication provides permanent links to original and updated versions of validated data files. The data files include properties of seawater, particulate matter and dissolved matter that were measured from discrete water samples collected with Niskin bottles during the 2009-2013 Tara Oceans expedition. Properties include pigment concentrations from HPLC analysis (10 depths per vertical profile, 25 pigments per depth), the carbonate system (Surface and 400m; pH (total scale), CO2, pCO2, fCO2, HCO3, CO3, Total alkalinity, Total carbon, OmegaAragonite, OmegaCalcite, and dosage Flags), nutrients (10 depths per vertical profile; NO2, PO4, N02/NO3, SI, quality Flags), DOC, CDOM, and dissolved oxygen isotopes. The Service National d'Analyse des Paramètres Océaniques du CO2, at the Université Pierre et Marie Curie, determined CT and AT potentiometrically (Edmond 1970; DOE 1994) on samples preserved according to Dickson et al. (2007). More than 250 vertical profiles of these properties were made across the world ocean. DOC, CDOM and dissolved oxygen isotopes are available only for the Arctic Ocean and Arctic Seas (2013).

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The monitoring of organisms' health conditions by the assessment of their immunocompetence may serve as an important criterion for the achievement of the Good Environmental Status (GES) as defined in the Marine Strategy Framework Directive (EU). In this context, the complex role of natural environmental stressors, e.g. salinity, and interfering or superimposing effects of anthropogenic chemicals, should be carefully considered, especially in scenarios of low to moderate contamination. Organisms from the Baltic Sea have adapted to the ambient salinity regime, however energetically costly osmoregulating processes may have an impact on the capability to respond to additional stress such as contamination. The assessment of multiple stressors, encompassing natural and anthropogenic factors, influencing an organisms' health was the main aim of the present study. Immune responses of Mytilus edulis, collected and kept at natural salinities of 12 per mil (LS) and 20 per mil (MS), respectively, were compared after short-term exposure (1, 7 and 13 days) to low copper concentrations (5, 9 and 16 µg/L Cu). A significant interaction of salinity and copper exposure was observed in copper accumulation. LS mussels accumulated markedly more copper than MS mussels. No combined effects were detected in cellular responses. Bacterial clearance was mostly achieved by phagocytosis, as revealed by a strong positive correlation between bacterial counts and phagocytic activity, which was particularly pronounced in LS mussels. MS mussels, on the other hand, seemingly accomplished bacterial clearance by employing additional humoral factors (16 µg/L Cu). The greatest separating factor in the PCA biplot between LS and MS mussels was the proportion of granulocytes and hyalinocytes while functional parameters (phagocytic activity and bacterial clearance) were hardly affected by salinity, but rather by copper exposure. In conclusion, immune responses of the blue mussel may be suitable and sensitive biomarkers for the assessment of ecosystem health in brackish waters (10-20 per mil S).

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Stable isotopic records across the Cretaceous/Paleogene (K/P) boundary in Maud Rise Holes 689B and 690C indicate that significant climatic changes occurred during the latest Cretaceous, beginning approximately 500 k.y. prior to the mass extinction event and the enrichment of iridium at the K/P boundary (66.4 Ma). An oxygen isotopic decrease of ~0.7 per mil - ~1.0 per mil is recorded in the Late Cretaceous planktonic and benthic foraminifers between 66.9 and 66.6 Ma. The negative isotope excursion was followed by a positive excursion of similar magnitude between 66.6 Ma (latest Cretaceous) and ~66.3 Ma (earliest Paleocene). No other isotopic excursions of this magnitude are recorded in the planktonic and benthic microfossil records 1.0 m.y prior to, and for 2.0 m.y following the mass extinction event at the K/P boundary. The magnitude and duration of these isotopic excursions were similar to those at the Paleocene/Eocene and Eocene/Oligocene boundaries. A major d13C excursion occurred 200 k.y. prior to the boundary, involving a positive shift in planktonic and benthic d13C of ~0.5 per mil - 0.75 per mil. Similar changes observed in other deep-sea sequences indicate that this reflected a global change in d13C of the oceanic total dissolved carbon (TDC) reservoir. The magnitude of this inferred carbon reservoir change and its association with high latitude surface-water temperature changes recorded in the d18O records implies that it was linked to global climate change through feedback loops in the carbon cycle. At the K/P boundary, the surface-to-deep water d13C gradient is reduced by approximately 0.6 per mil - ~0.2 per mil. However, unlike sequences elsewhere, the planktonic-benthic d13C gradient (Delta d13C) was not eliminated in the Antarctic. The surface-to-deep water gradient was re-established gradually during the 400 k.y. following the mass extinction. Full recovery of the Delta d13C occurred by ~60.0 Ma. In addition to the reduced vertical d13C gradient across the K/P boundary, there was a negative excursion in both planktonic and benthic d13C beginning approximately 100 k.y. after the boundary (66.3 Ma). This excursion resulted in benthic d13C values in the early Paleogene that were similar to those in the pre-K/P boundary intervals. This negative shift appears to reflect a change in the d13C of the oceanic TDC reservoir shift that may have resulted from reduced carbon burial and/or increased carbon flux to the oceans. Any model that attempts to explain the demise of the oceanic plankton at the end of the Cretaceous should consider the oceanic environmental changes that were occurring prior to the massive extinction event.

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Mode of access: Internet.

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The Baltic Sea is a unique environment as the largest body of brackish water in the world. Acidification of the surface oceans due to absorption of anthropogenic CO2 emissions is an additional stressor facing the pelagic community of the already challenging Baltic Sea. To investigate its impact on trace gas biogeochemistry, a large-scale mesocosm experiment was performed off Tvärminne Research Station, Finland in summer 2012. During the second half of the experiment, dimethylsulphide (DMS) concentrations in the highest fCO2 mesocosms (1075-1333 µatm) were 34 % lower than at ambient CO2 (350 µatm). However the net production (as measured by concentration change) of seven halocarbons analysed was not significantly affected by even the highest CO2 levels after 5 weeks exposure. Methyl iodide (CH3I) and diiodomethane (CH2I2) showed 15 % and 57 % increases in mean mesocosm concentration (3.8 ± 0.6 pmol L-1 increasing to 4.3 ± 0.4 pmol L-1 and 87.4 ± 14.9 pmol L-1 increasing to 134.4 ± 24.1 pmol L-1 respectively) during Phase II of the experiment, which were unrelated to CO2 and corresponded to 30 % lower Chl-? concentrations compared to Phase I. No other iodocarbons increased or showed a peak, with mean chloroiodomethane (CH2ClI) concentrations measured at 5.3 (± 0.9) pmol L-1 and iodoethane (C2H5I) at 0.5 (± 0.1) pmol L-1. Of the concentrations of bromoform (CHBr3; mean 88.1 ± 13.2 pmol L-1), dibromomethane (CH2Br2; mean 5.3 ± 0.8 pmol L-1) and dibromochloromethane (CHBr2Cl, mean 3.0 ± 0.5 pmol L-1), only CH2Br2 showed a decrease of 17 % between Phases I and II, with CHBr3 and CHBr2Cl showing similar mean concentrations in both Phases. Outside the mesocosms, an upwelling event was responsible for bringing colder, high CO2, low pH water to the surface starting on day t16 of the experiment; this variable CO2 system with frequent upwelling events implies the community of the Baltic Sea is acclimated to regular significant declines in pH caused by up to 800 µatm fCO2. After this upwelling, DMS concentrations declined, but halocarbon concentrations remained similar or increased compared to measurements prior to the change in conditions. Based on our findings, with future acidification of Baltic Sea waters, biogenic halocarbon emissions are likely to remain at similar values to today, however emissions of biogenic sulphur could significantly decrease from this region.

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Thesis (Ph.D.)--University of Washington, 2016-06