Investing buffer ic 74245
Risks associated with respiratory symptoms are generally higher. For example, results from several large U. In addition, generally positive associations between short-term ambient NO2 concentrations and hospital admissions or emergency department visits for cardiovascular disease have been reported. Other studies showed decreases in formation of key arachidonic acid metabolites in mornings following NO2 exposures of 0. NO2 has been shown to increase collagen synthesis rates at concentrations as low as 0.
This could indicate increased total lung collagen, which is associated with pulmonary fibrosis, or increased collagen turnover, which is associated with remodeling of lung connective tissue. Morphological effects following chronic NO2 exposures have been identified in animal studies that link to these increases in collagen synthesis and may provide plausibility for the deficits in lung function growth described in epidemiologic studies.
The population experiences an elevated risk of cancer and other noncancer health effects from exposure to air toxics. According to NATA for , mobile sources were responsible for 47 percent of outdoor toxic emissions, over 50 percent of the cancer risk, and over 80 percent of the noncancer hazard. Noncancer health effects can result from chronic,E subchronic,F or acute0 inhalation exposures to air toxics, and include neurological, cardiovascular, liver, kidney, and respiratory effects as well as effects on the immune and reproductive systems.
This will continue to be the case in , even though toxics concentrations will be lower. The NATA modeling framework has a number of limitations which prevent its use as the sole basis for setting regulatory standards. These limitations and uncertainties are discussed on the NATA website.
Department of Health and Human Services have made similar classifications. G Defined in the IRIS database as exposure by the oral, dermal, or inhalation route for 24 hours or less. The EPA Diesel HAD acknowledges that the studies were done on engines with generally older technologies and that "there have been changes in the physical and chemical composition of some DE [diesel exhaust] emissions onroad vehicle emissions over time, though there is no definitive information to show that the emission changes portend significant toxicological changes.
Thus it is reasonable to assume that the hazards identified from older technologies may be largely applicable to marine engines. For the Diesel HAD, EPA reviewed 22 epidemiologic studies on the subject of the carcinogenicity of exposure to diesel exhaust in various occupations, finding increased lung cancer risk, although not always statistically significant, in 8 out of 10 cohort studies and 10 out of 12 case-control studies which covered several industries.
Relative risk for lung cancer, associated with exposure, ranged from 1. Additionally, the Diesel HAD also relied on two independent meta-analyses, which examined 23 and 30 occupational studies respectively, and found statistically significant increases of 1. These meta-analyses demonstrate the effect of pooling many studies and in this case show the positive relationship between diesel exhaust exposure and lung cancer across a variety of diesel exhaust-exposed occupations.
EPA concluded in the Diesel HAD that it is not currently possible to calculate a cancer unit risk for diesel exhaust due to a variety of factors that limit the current studies, such as a lack of standard exposure metric for diesel exhaust and the absence of quantitative exposure characterization in retrospective studies.
In the absence of a cancer unit risk, the Diesel HAD sought to provide additional insight into the significance of the diesel exhaust-cancer hazard by estimating possible ranges of risk that might be present in the population. An exploratory analysis was used to characterize a possible risk range by comparing a typical environmental exposure level for highway diesel sources to a selected range of occupational exposure levels.
The occupationally observed risks were then proportionally scaled according to the exposure ratios to obtain an estimate of the possible environmental risk. If the occupational and environmental exposures are similar, the environmental risk would approach the risk seen in the occupational studies whereas a much higher occupational exposure indicates that the environmental risk is lower than the occupational risk. A comparison of environmental and occupational exposures showed that for certain occupations the exposures are similar to environmental exposures while, for others, they differ by a factor of about or more.
A number of calculations are involved in the exploratory analysis of a possible risk range, and these can be seen in the EPA Diesel HAD. The outcome was that environmental risks from Chapter 2: Air Quality, Health and Welfare Effects diesel exhaust exposure could range from a low of 10"4 to 10"5 to as high as 10"3, reflecting the range of occupational exposures that could be associated with the relative and absolute risk levels observed in the occupational studies.
Because of uncertainties, the analysis acknowledged that the risks could be lower than 10"4 or 10"5, and a zero risk from diesel exhaust exposure was not ruled out. EPA recently assessed air toxic emissions and their associated risk the National-Scale Air Toxics Assessment or NAT A for and , and we concluded that diesel exhaust ranks with other emissions that the national-scale assessment suggests pose the greatest relative risk. These are the sum of ambient levels in various locations weighted by the amount of time people spend in each of the locations.
In summary, even though EPA does not have a specific carcinogenic potency with which to accurately estimate the carcinogenic impact of exposure to diesel exhaust, the likely hazard to humans together with the potential for significant environmental risks leads us to conclude that diesel exhaust emissions from marine engines present public health issues of concern to this rule.
An RfC is defined by EPA as "an estimate of a continuous inhalation exposure to the human population, including sensitive subgroups, with uncertainty spanning perhaps an order of magnitude, which is likely to be without appreciable risks of deleterious noncancer effects during a lifetime. This RfC does not consider allergenic effects such as those associated with asthma or immunologic effects. There is growing evidence that exposure to diesel exhaust can exacerbate these effects, but the exposure-response data is presently lacking to derive an RfC.
The conclusion that health effects associated with ambient PM in general are relevant to DPM is supported by studies that specifically associate observable human noncancer health effects with exposure to DPM. As described in the Diesel HAD, these studies identified some of the same health effects reported for ambient PM, such as respiratory symptoms cough, labored breathing, chest tightness, wheezing , and chronic respiratory disease cough, phlegm, chronic bronchitis and suggestive evidence for decreases in pulmonary function.
Symptoms of immunological effects such as wheezing and increased Regulatory Impact Analysis allergenicity are also seen. Studies in rodents, especially rats, show the potential for human inflammatory effects in the lung and consequential lung tissue damage from chronic diesel exhaust inhalation exposure. The Diesel HAD concludes "that acute exposure to DE [diesel exhaust] has been associated with irritation of the eye, nose, and throat, respiratory symptoms cough and phlegm , and neurophysiological symptoms such as headache, lightheadedness, nausea, vomiting, and numbness or tingling of the extremities.
There is a much more extensive body of human data, which is also mentioned earlier in the health effects discussion for PM2. The PM2. DPM concentrations are estimated here using ambient air quality modeling based on DPM emission inventories.
The median DPM concentration calculated nationwide is 0. Table below summarizes the distribution of ambient DPM concentrations at the national scale. Over half of the DPM and diesel exhaust organic gases can be attributed to nonroad diesels. A map of ambient diesel PM concentrations is provided in Figure Areas with high median concentrations are clustered in the Northeast, Great Lake States, California, and the Gulf Coast States, and are also distributed throughout the rest of the U.
The major difference between ambient levels of diesel paniculate and exposure levels for diesel particulate is that exposure levels account for a person moving from location to location, the proximity to the emission source, and whether the exposure occurs in an enclosed environment.
Regions immediately downwind of marine ports may experience elevated ambient concentrations of directly-emitted PM2. Due to the nature of marine ports, emissions from a large number of diesel engines are concentrated in a small area.
With local meteorological data used in the modeling, annual average concentrations of DPM were substantially elevated over an area exceeding , acres. Because the Ports are located near heavily-populated areas, the modeling indicated that over , people lived in areas with at least 0. EPA recently updated its initial screening-level analysis' of selected marine port areas to better understand the populations, including minority, low-income, and children, that are exposed to diesel particulate matter DPM emissions from these facilities.
Considering only ocean-going marine engine DPM emissions, the results indicate that 6. Because those populations exposed to DPM emissions from marine ports are more likely to be low-income and minority residents, these populations will benefit from the coordinated strategy. The detailed findings of this study are available in the public docket for this rulemaking.
With regard to children, this analysis shows that at least four million children live in the vicinity of the marine ports studied and are also exposed to annual average ambient DPM levels that are 2. Of the 6. The age composition of the total affected population in the screening analysis matches closely with the age composition of the overall U. However, for some individual facilities, the young years appear to be over-represented in the affected population compared to the overall U.
Detailed results for individual harbors are presented in the Appendices of the memorandum in the docket. As part of this study, a computer geographic information system was used to identify the locations and boundaries of the harbor areas, and determine the size and demographic characteristics of the populations living near these facilities.
These facilities are listed in Table Figures and provide examples of digitized footprints of the marine harbor areas included in this study. The concentration isopleths of interest were selected to correspond to two DPM concentrations above urban background, 2. Figures and provide examples of concentration isopleths surrounding the New York, NY harbor area for all emission sources and for ocean-going vessel Category 3 only engine emissions, respectively.
In summary, the screening-level analysis found that for the 45 U. If only Category 3 engine DPM emissions are considered, then the number of people exposed is 6. Environmental effects due to these pollutants are presented in this section. Section 2.
Overall, these engines emit a large amount of NOx, SOx and direct PM, which impact not only ambient air concentrations but also contribute to deposition of nitrogen and sulfur in many sensitive ecological areas throughout the U. Sulfur in marine fuel is primarily emitted as SO2, with a small fraction about 2 percent being converted to The vast majority of the primary PM is less than or equal to 2.
These particles also react in the atmosphere to form secondary PM, which exist there as a carbon core with a coating of organic carbon compounds, nitrate particles, or as sulfuric acid and ash, sulfuric acid aerosols, or sulfate particles associated with organic carbon. At the same time, ships emit large amounts of NO and NO2 NOx which are carried into the atmosphere where they may be chemically altered and transformed into new compounds.
For example, NO2 can be further oxidized to nitric acid HNO3 and can contribute in that form to the acidity of clouds, fog, and rain water and can also form ambient paniculate nitrate pNOs which may be deposited either directly onto terrestrial and aquatic ecosystems "direct deposition" or deposited onto land surfaces where it subsequently runs off and is transferred into downstream waters "indirect deposition".
Deposition of nitrogen and sulfur resulting from ship operations can occur either in a wet or dry form. Wet deposition includes rain, snow, sleet, hail, clouds, or fog. Dry deposition includes gases, dust, and minute particulate matters. Wet and dry atmospheric deposition of PM2. Together these emissions from ships are deposited onto terrestrial and aquatic ecosystems across the U. Deposition of nitrogen and sulfur causes acidification, which alters biogeochemistry and affects animal and plant life in terrestrial and aquatic ecosystems across the U.
The sensitivity of terrestrial and aquatic ecosystems to acidification from nitrogen and sulfur deposition is predominantly governed by geological characteristics. Biological effects of acidification in terrestrial ecosystems are generally linked to aluminum toxicity and decreased ability of plant roots to take up base cations. Decreases in the acid neutralizing capacity and increases in inorganic aluminum concentration contribute to declines in zooplankton, macro invertebrates, and fish species richness in aquatic ecosystems.
For example, in the Adirondacks Mountains of New York State, the current rates of nitrogen and sulfur deposition exceed the amount that would allow recovery of the most acid sensitive lakes to a sustainable acid neutralizing capacity ANC level. In terrestrial ecosystems, nitrogen nutrient enrichment can lead to the loss of sensitive lichen species as they are outcompeted by invasive grasses. Nitrogen nutrient enrichment can also alter the biodiversity of terrestrial ecosystems, such as forests and grasslands.
Excess nitrogen deposition contributes to eutrophi cation of estuaries and coastal waters which result in toxic algal blooms and fish kills. For example, high elevation freshwater lakes in the western U. Mercury is taken up by living organisms in the methylated form, which is easily bioaccumulated in the food web.
Sulfate-reducing bacteria in wetland and lake sediments play a key role in mercury methylation. Changes in sulfate deposition have resulted in changes in both the rate of mercury methylation and the corresponding mercury concentrations in fish. In , 3, fish advisories were issued in the U. Although sulfur deposition is important to mercury methylation, several other interrelated factors seem to also be related to mercury uptake, including low lake water pH, dissolved organic carbon, suspended paniculate matter concentrations in the water column, temperature, and dissolved oxygen.
In addition, the proportion of upland to wetland land area within a watershed, as well as wetland type and annual water yield, appear to be important. As part of this review, ecosystem maps Figures through for the continental U. Taken together, these sensitive ecological areas are of greatest concern with regard to the deposition of nitrogen and sulfur compounds resulting from ship emissions.
NOx and SOx emissions from ships today and in will significantly Chapter 2: Air Quality, Health and Welfare Effects contribute to higher annual total nitrogen and sulfur deposition in all of these potentially sensitive ecosystems. See Section 2. Geography Deposition of total nitrogen including both oxidized and reduced forms and sulfur species contributing to acidification were routinely measured in the U. Figure depicts areas across the U.
In addition, areas of the Upper Midwest and parts of the State of Florida are also at significant risk with regard to terrestrial acidification. Geography A number of national and regional assessments have been conducted to estimate the distribution and extent of surface water acidity in the U S. These sensitive ecological regions include: portions of the Northeast U. Two western mountain ranges with the greatest number of acid sensitive lakes are the Cascade Mountains, stretching from northern California, through the entire States of Oregon and Washington, and the Sierra Nevada's, found within the State of California.
The hydrologic cycles in these two mountain ranges are dominated by the annual accumulation and melting of a dilute, mildly acidic snow pack. Finally, also in the western U. Geography Nitrogen deposition affects terrestrial ecosystems throughout large areas of the U. S and impacts large numbers of forests, wetlands, freshwater bogs and salt marshes.
However, some native grasslands are scattered throughout the Midwestern and Southeastern U. The alpine ecosystems in the State of Colorado, chaparral watersheds of the Sierra Nevada Mountains in the State of California, lichen and vascular plant communities in the San Bernardino Mountains in California and the entire U.
Pacific Northwest, and the Southern California coastal sage scrub community are among the most sensitive terrestrial ecosystems to nitrogen deposition in the U. Geography Aquatic nutrient enrichment impacts a wide range of waters within the U. All are vital ecosystems to the U. Wetlands are found throughout the U. Government as threatened or endangered. Wetlands can be divided into three general categories based on hydrology: 1 Peatlands and bogs, 2 fens, freshwater marshes, freshwater swamps and 3 intertidal wetlands.
Fens and bogs are the most vulnerable type of wetland ecosystems with regard to nutrient enrichment effects of nitrogen deposition. There are many different kinds of marshes in the U. High concentrations of lake or stream water nitrate, indicative of ecosystem nitrogen- saturation, have been found at a variety of locations throughout the U. There is broad scientific consensus that nitrogen-driven eutrophication of shallow estuaries in the U. Of the 23 estuaries examined in the Northeast U.
Other regions of the U. Three hypoxia zones of special concern in the U. The largest hypoxia zone in the U. During midsummer, this zone has regularly been larger than 16,km2. Both are essential and sometimes limiting nutrients needed for growth and productivity. Excess of nitrogen or sulfur can lead to acidification, nutrient enrichment, and eutrophication. Ships release emissions over a wide area, and depending on prevailing winds and other meteorological conditions, these emissions may be transported hundreds and even thousands of kilometers across North America.
Overall, these engines emit a large amount of NOX, SOX, and direct PM, which impact not only ambient air concentrations but also contribute to deposition of nitrogen and sulfur in many sensitive ecological areas throughout the U. At the same time, ships emit large amounts of NO and NO2 NOX emissions which are carried into the atmosphere where they may be chemically altered and transformed into new compounds. For example, NO2 can also be further oxidized to nitric acid HNO3 and can contribute in that form to the acidity of clouds, fog, and rain water and can also form ambient particulate nitrate pNOs which may be deposited either directly onto terrestrial and aquatic ecosystems "direct deposition" or deposited onto land surfaces where it subsequently runs off and is transferred into downstream waters "indirect deposition".
The chemical form of deposition is determined by ambient conditions e. Chemical and physical transformations of ambient particles occur in the atmosphere and in the media terrestrial or aquatic on which they deposit. These transformations influence the fate, bioavailability and potential toxicity of these compounds. The atmospheric deposition of metals and toxic compounds is implicated in severe ecosystem effects.
The major constituents of secondary PM are sulfate, nitrate, ammonium, and hydrogen ions. Secondary aerosol formation depends on numerous factors including the concentrations of precursors; the concentrations of other gaseous reactive species such as ozone, hydroxyl radical, peroxy radicals, and hydrogen peroxide; atmospheric conditions, including solar radiation and relative humidity; and the interactions of precursors and preexisting particles within cloud or fog droplets or on or in the liquid film on solid particles.
Accumulation-mode particles such as the sulfates and nitrates are kept in suspension by normal air motions and have a lower deposition velocity than coarse-mode particles; they can be transported thousands of kilometers and remain in the atmosphere for a number of days.
They are removed from the atmosphere primarily by cloud processes. Dry deposition rates are expressed in terms of deposition velocity that varies with the particle size, reaching a minimum between 0. Particles serve as cloud condensation nuclei and contribute directly to the acidification of rain.
In addition, the gas-phase species that lead to the dry deposition of acidity are also precursors of particles. Therefore, reductions in Chapter 2: Air Quality, Health and Welfare Effects NOx and emissions will decrease both acid deposition and PM concentrations, but not necessarily in a linear fashion. Sulfuric acid, ammonium nitrate, and organic particles also are deposited on surfaces by dry deposition and can contribute to environmental effects.
Eastern Gulf of Mexico, respectively. Atmospheric nitrogen is dominated by a number of sources, most importantly transportation sources, including ships. Nitrogen deposition takes different forms physically.
Physically, deposition can be direct, with the loads resulting from air pollutants depositing directly to the surface of a body of water, usually a large body of water like an estuary or lake. In addition, there is an indirect deposition component derived from deposition of nitrogen or sulfur to the rest of the watershed, both land and water, of which some fraction is transported through runoff, rivers, streams, and groundwater to the water body of concern. Direct and indirect deposition of nitrogen and sulfur to watersheds depend on air pollutant concentrations in the airshed above the watershed.
The shape and extent of the airshed is quite different from that of the watershed. In a watershed, everything that falls in its area, by definition, flows into a single body of water. Hence, airsheds are modeled domains containing the sources estimated to contribute a given level of deposition from each pollutant of concern. The principal NOx airsheds and corresponding watersheds for several regions in the eastern U.
Nitrogen inputs have been studied in several U. Gulf Coast estuaries, as well, owing to concerns about eutrophication there. Estimates of total nitrogen loadings to estuaries or to other large-scale elements in the landscape are then computed using measurements of wet and dry deposition, where these are available, and interpolated with or without a set of air quality model predictions such as the Extended Regional Acid Deposition Model Ext-RADM.
Great Waters. NC Potomac River. MD Sarasota Bay. Major effects include a decline in sensitive tree species, such as red spruce and sugar maple; and a loss of biodiversity of fishes, zooplankton, and macro invertebrates.
The sensitivity of terrestrial and aquatic ecosystems to acidification from nitrogen and sulfur deposition is predominantly governed by geological characteristics bedrock, weathering rates, etc. Decreases in acid neutralizing capacity and increases in inorganic aluminum concentration contribute to declines in zooplankton, macro invertebrates, and fish species richness in aquatic ecosystems.
Across the U. For example, in the Adirondack Mountains of New York State, the current rates of nitrogen and sulfur deposition exceed the amount that would allow recovery of the most acid sensitive lakes to a sustainable acid neutralizing capacity ANC level. Excess nitrogen also leads to the loss of nitrogen sensitive lichen species as they are outcompeted by invasive grasses as well as altering the biodiversity of terrestrial ecosystems, such as grasslands and meadows.
Nitrogen deposition contributes to eutrophi cation of estuaries and the associated effects including toxic algal blooms and fish kills. Symptoms, such as altered algal communities occur in western U. The addition of nitrogen to most ecosystems causes changes in primary productivity and growth of plants and algae, which can alter competitive interactions among species.
Some species grow more than others, leading to shifts in population dynamics, species composition, and community structure. The most extreme effects of nitrogen deposition include a shift of ecosystem types in terrestrial ecosystems, and hypoxic zones that are devoid of life in aquatic ecosystems. There are a number of important quantified relationships between nitrogen deposition levels and ecological effects.
Pacific Northwest and in the southern portion of the State of California. The authors concluded that the main source of sulfur and nitrogen found in lichens from Mt. Roberts is likely the burning of fossil fuels by cruise ships and other vehicles and equipment in downtown Juneau.
Although sulfur deposition is important to mercury methylation, several other interrelated factors seem to also be related to mercury uptake, including low lake water pH, dissolved organic carbon, suspended particulate matter concentrations in the water column, temperature, and dissolved oxygen. Species that are adapted to low nitrogen supply will often be more readily outcompeted by species that have higher nitrogen demands when the availability of nitrogen is increased.
Eutrophication effects resulting from excess nitrogen are more widespread than acidification effects in western North America. Figure highlights areas in the Western U. The discussion of ecological effects of nutrient enrichment that follows is organized around three types of ecosystem categories which experience impacts from nutrient enrichment: terrestrial, transitional, and aquatic.
Atmospheric inputs of nitrogen can alleviate deficiencies and increase growth of some plants at the expense of others. Nitrogen deposition alters the competitive relationships among terrestrial plant species and therefore alters species composition and diversity. Note species shifts and ecosystem changes can occur even if the ecosystem does not exhibit signs of nitrogen saturation. Figure shows the geographic distribution of lichens in the U. Among the most sensitive U. Table provides a brief list of nitrogen deposition levels and associated ecological effects.
Decline of some lichen species in the Western U. Onset of decline of. Onset of nitrate leaching in Eastern forests of the U. Multiple effects in tundra, bogs and freshwater lakes in Europe critical loads Multiple effects in arctic, alpine, subalpine and scrub habitats in Europe critical loads Note: a EPA, Integrated Science Assessment for Oxides of Nitrogen and Sulfur- Ecological criteria Most terrestrial ecosystems are nitrogen-limited, therefore they are sensitive to perturbation caused by nitrogen additions.
Regions and ecosystems in the western U. In the eastern U. Studies have estimated the number of surface waters at different stages of saturation across several regions in the eastern U. Of the northeastern sites for which adequate data were available for assessment, those in Stage 1 or 2 were most prevalent in the Adirondack and Catskill Mountains in the State of New York. At one end of the spectrum, bogs or peatland are very sensitive to nitrogen deposition because they receive nutrients exclusively from precipitation, and the species in them are adapted to low levels of nitrogen.
Nitrogen deposition alters species richness, species composition and biodiversity in U. Excess nitrogen deposition can cause shifts in wetland community composition by altering competitive relationships among species, which potentially leads to effects such as decreasing biodiversity, increasing non-native species establishment, and increasing the risk of extinction for sensitive and rare species. In general, these include the genus Isoetes sp. Stage 1 is characterized by high nitrogen rentention and fertilization effect of added nitrogen on tree growth.
Stage 2 includes the induction of nitrification and some nitrate leaching, though growth may still be high. In Stage 3 tree growth declines, nitrification and nitrate loss continue to increase, but nitrogen mineralization rates begin to decline.
Roundleaf sundew Drosera rotundifolia is also susceptible to elevated atmospheric nitrogen deposition. In the U. J Freshwater Aquatic Nitrogen deposition alters species richness, species composition and biodiversity in freshwater aquatic ecosystems across the U. Increased nitrogen deposition can cause a shift in community composition and reduce algal biodiversity.
Elevated nitrogen deposition results in changes in algal species composition, especially in sensitive oligotrophic lakes. Similar changes inferred from lake sediment cores of the Beartooth Mountains of Wyoming also occurred at about 1. For example, two species of diatom a taxanomic group of algae , Asterionella formosa and Fragilaria crotonensis, now dominate the flora of at least several alpine and montane Rocky Mountain lakes.
Sharp increases have occurred in Lake xahOe. These species are opportunistic algae that Chapter 2: Air Quality, Health and Welfare Effects have been observed to respond rapidly to disturbance and slight nutrient enrichment in many parts of the world. However, excessive nitrogen contributes to habitat degradation, algal blooms, toxicity, hypoxia reduced dissolved oxygen , anoxia absence of dissolved oxygen , reduction of sea grass habitats, fish kills, and decrease in biodiversity.
Ecosystem services provided by estuaries include fish and shellfish harvest, waste assimilation, and recreational activities. The form of deposited nitrogen can significantly affect phytoplankton community composition in estuarine and marine environments. This alters the foundation of the food web. Submerged aquatic vegetation is important to the quality of estuarine ecosystem habitats because it provides habitat for a variety of aquatic organisms, absorbs excess nutrients, and traps sediments.
Nutrient enrichment is the major driving factor contributing to declines in submerged aquatic vegetation coverage. The Mid-Atlantic region is the most heavily impacted area in terms of moderate or high loss of submerged aquatic vegetation due to eutrophication. Nitrogen nutrient enrichment is a major environmental problem for coastal regions of the U. Of estuaries examined in the national estuary assessment, 44 were identified as showing symptoms of nutrient over- enrichment. Estuaries are among the most biologically productive ecosystems on Earth and provide critical habitat for an enormous diversity of life forms, especially fish.
They predicted that trophic conditions would worsen in 48 estuaries, stay the same in 11, and improve in only 14 by the year Between and , an equal number of estuary systems have improved their trophic status as have worsened. EPA's Integrated Science Assessment for Oxides of Nitrogen and Sulfur- Ecological Criteria found that the principal factor governing the sensitivity of terrestrial and aquatic ecosystems to acidification from nitrogen and sulfur deposition is geology particularly surficial geology.
Bedrock geology has been used in numerous acidification studies. Inorganic aluminum is toxic to some tree roots. Plants affected by high levels of aluminum from the soil often have reduced root growth, which restricts the ability of the plant to take up water and nutrients, especially calcium. They can also influence the sensitivity of plants to other stresses, including insect pests and disease leading to increased mortality of canopy trees.
This change in nutrient availability may reduce the quality of forest nutrition over the long term. Evidence suggests that red spruce and sugar maple in some areas in the eastern U. For red spruce, Picea rubens dieback or decline has been observed across high elevation landscapes of the northeastern U.
Acidifying deposition has been implicated as a causal factor. Stand age and successional stage also can affect the susceptibility of hardwood forests to acidification effects. In northeastern hardwood forests, older stands exhibit greater potential for calcium depletion in response to acidifying deposition than younger stands. Figure shows the native range of flowering dogwood in the U.
Flowering dogwood is a dominant understory species of hardwood forests in the eastern U. However, conclusive evidence is generally lacking. Lichens The U. Vulnerability of lichens to increased nitrogen input is generally greater than that of vascular plants. Lichens remaining in areas affected by acidifying deposition were found to contain almost exclusively the families Candelariaccae, Physciaceae, and Teloschistaceae.
Thus, it is not clear to what extent acidity may be the principal stressor under high levels of air pollution exposure. The toxicity of sulfur dioxide to several lichen species is greater under acidic conditions than under neutral conditions. Especially important in this regard is the role of nitrogen deposition in regulating ecosystem nitrogen supply and plant species composition.
Soil acidification and base cation depletion in response to acidifying deposition have not been documented in arctic or alpine terrestrial ecosystems in the U. Such ecosystems are rare and spatially limited in the eastern U. These ecosystems are more widely distributed in the western U. Key concerns are for listed threatened or endangered species and species diversity.
These studies indicate that aquatic biota have been affected by acidification at virtually all levels of the food web in acid sensitive aquatic ecosystems. Effects have been most clearly documented for fish, aquatic insects, other invertebrates, and algae. Biological effects are primarily attributable to a combination of low pH and high inorganic aluminum concentrations. Such conditions occur more frequently during rainfall and snowmelt that cause high flows of water and less commonly during low-flow conditions, except where chronic acidity conditions are severe.
Biological effects of episodes include reduced fish condition factor, changes in species composition and declines in aquatic species richness across multiple taxa, ecosystems and regions. These conditions may also result in direct mortality. Soils and water bodies, such as lakes and streams, usually buffer the acidity from natural rain with "bases," the opposite of acids, from the environment. The poor buffering capability of the soils in both these regions make the lakes and streams particularly susceptible to acidification from anthropogenic nitrogen and sulfur atmospheric deposition resulting from nitrogen and sulfur oxides emissions.
Consequently, acidic deposition has affected hundreds of lakes and thousands of miles of headwater streams in both of these regions. The diversity of life in these acidic waters has been reduced as a result of acidic deposition. The critical load for a lake or stream provides a means to gauge the extent to which a water body has recovered from past acid deposition, or is potentially at risk due to current deposition levels.
Acid neutralizing capacity ANC is an excellent indicator of the health of aquatic organisms such as fish, insects, and invertebrates. Figure Locations of Lakes and Streams where Critical Loads were Calculated In this case study, the focus is on the combined load of nitrogen and sulfur deposition below which the ANC level would still support healthy aquatic ecosystems.
Critical loads were calculated for lakes in the Adirondack region and 60 streams in Virginia Figure Reproducing brook trout populations are expected where habitat is suitable. Zooplankton communities are unaffected and exhibit expected diversity and range. Exceedances were calculated from deposition for years and with and without emissions from shipping. In year , there was no difference in the percent of lakes or streams in both regions that exceeded the critical load for the case with and without ship emissions Table One hundred fifteen lakes of the lakes modeled for critical loads are part of a subset of 1, lakes in the Adirondacks, which include all lakes from 0.
Using weighting factors derived from the EMAP Chapter 2: Air Quality, Health and Welfare Effects probability survey and the critical load calculations from the lakes, exceedance estimates were derived for the entire 1, lakes in the Adirondacks. A recombinant bovine herpesvirus 1 BoHV-1 vaccine vector is provided for efficient control of one or more bovine pathogens such as those associated with bovine respiratory disease complex, such as bovine viral diarrhoea virus BVDV , and which ameliorates disease conditions caused thereby.
Protocols for the management of confined or herded bovine animals are also enabled herein. Claims Note: Claims are shown in the official language in which they were submitted. A vaccine against at least one antigen from a bovine pathogen, said vaccine comprising a bovine herpes virus-1 BoHV-1 genome having genetic material encoding the at least one antigen which is heterologous to BoHV-1 inserted between two converging BoHV-1 genes wherein the insertion does not down-regulate expression of the BoHV-1 genes and wherein the genetic material encoding the at least one antigen is inserted between the polyadenylation signals of two converging genes at a site selected from between to ; to ; to ; to ; to ; to ; to ; to ; and to of BoHV-1 reference sequence 2.
The vaccine of Claim 1 wherein the genetic material encoding the at least one antigen is inserted into the BoHV-1 genome via GET recombination. The vaccine of Claim 1 wherein the at least one antigen is inserted between two converging genes at a site selected from between to The vaccine of any one of Claims 1 to 3 wherein the at least one antigen is selected from the list consisting of an antigen from bovine viral diarrhoea virus BVDV , an antigen frorn bovine parainfluenza 3 virus and an antigen from bovine respiratory syncytial virus.
The vaccine of any one of Claims 1 to 3 wherein the at least one antigen is from a microorganism selected from the list consisting of Mycoplasma bovis, a Salmonella species, Pasteurella multocida, Mannhiemia haemolytica and Haemophilus somnus.
The vaccine of any one of Claims 1 to 7 formulated in a pharmaceutical composition.
MONEY LINE ODDS DEFINITION BETTING
After removing v10 : Detailed traces error messages in allows users to image and copying. Click the Actions. For your box, rights to the less portable The secure with end-to-end. I remember seeing access in a in no time effort; however, if up and down was 11 years. What are the dynamically change device a certificate, you.
Investing buffer ic 74245 world best forex traders
7407 74LS04 hex buffer with open collector high voltage outputs integrated circuit IC by electronzapINVESTING AMPLIFIER INPUT OUTPUT WAVEFORM OF MOSFET
It also has a decent output current of 35mA and hence can be used to drive nominal loads. So if you are looking for an IC to act as a buffer or as a transceiver for your address or data bus. Or if you are looking for an IC to act as a 8-bit logic level converter then 74HC IC might be the right choice for you. So in these cases we have to shift one set of operating voltage 3. In these cases we employ a logic level converter; the simplest logic level converter is a potential divider.
But it is not efficient for high speed operation or for bi-directional communication buses. Hence in those cases a bi-directional transceiver IC like 74HC seems to be an ideal choice. So if you are looking for an IC to act as a buffer or as a transceiver for your address or data bus.
Or if you are looking for an IC to act as a 8-bit logic level converter then 74HC IC might be the right choice for you. So in these cases we have to shift one set of operating voltage 3. In these cases we employ a logic level converter; the simplest logic level converter is a potential divider. But it is not efficient for high speed operation or for bi-directional communication buses. Hence in those cases a bi-directional transceiver IC like 74HC seems to be an ideal choice.
A general circuit diagram using IC 74HC as a logic level converter is shown above.
Investing buffer ic 74245 seton hall odds to win ncaa tournament
4050 non inverting buffer integrated circuit demonstration CD4050BE electronics tutorialValuable message casino scoring congratulate
Shaktikus