Acid rain deposition patterns in the continental United States

Acid rain has become a major environmental concern, the current extent of which is illustrated in this paper. Maps of both pH and H⁺ deposition in precipitation have been developed for the continental United States by analyzing laboratory pH data from nine precipitation chemistry networks and two single stations spread across the continental United States and southern Canada during the late 1970's. Average laboratory pH values were obtained or calculated for approximately 100 stations, and isopleths of weighted mean pH and mean annual H+ deposition in precipitation were drawn. Results of this analysis show that in spite of a wide variety of collection methods and sampling intervals, there is remarkable uniformity in the average pH among the various stations. The northeastern United States continues to exhibit the most acidic precipitation, with remaining portions of the eastern United States, states along the western coastline and a pocket in central Colorado also experiencing acid precipitation.     

Estimation of S and NOx-N deposition budgets for the United States and Canada

Extensive wet deposition monitoring data, along with much sparser dry deposition monitoring data and isolated field characterizations of droplet deposition, are used to produce an annual deposition budget for S and NO_x-N for each contiguous U.S. state and Canadian province. The contribution to wet deposition from natural sources is estimated, and wet deposition is adjusted accordingly, to focus the analysis on deposition associated with anthropogenic emissions. The budgets, which are appropriate for 1985–1987, include adjustments for increased local wet and dry deposition near point sources and urban areas, which are generally avoided in selecting monitoring sites. When aggregated over the United States and Canada, estimated wet, dry, and droplet deposition account for about 30, 29, and 4% of anthropogenic S emissions, respectively, implying that 37% is exported. For NO_x-N, estimated wet, dry, and droplet deposition account for 30, 43, and 4% of anthropogenic emissions, with 23% exported. Results are in general agreement with a variety of other observational analyses and regional modeling simulations, particularly for eastern North America, and are consistent with estimates of net horizontal mass fluxes of S and NO_x-N across the Atlantic coast of North America.     

Hydrogen ion speciation in the acid precipitation of the northeastern United States

The acidity of precipitation in rural, forested areas of the northeastern United States is dominated by the strong mineral acids: H₂SO₄ and HN0₃. Weak acids have a negligible effect on the measured acidity (pH) of precipitation. These conclusions are based on total acidity titrations and detailed analysis of organic and inorganic components in precipitation.     

Seasalt and pollution inputs over the continental United States

The average deposition rate of sea salt chloride over the world continents is about 10 meq m^?2 yr^?1. Only about 14 ± 1% of chloride in the pollution-corrected world average river is contributed by seasalt aerosols and the rest from the dissolution of evaporites. The significant increase of the ion concentrations in the Mississippi river from the year 1905 to 1987 was caused by anthropogenic inputs such as fossil fuel burning, common salt consumption, and dissolution of carbonate and silicate rocks by acids derived from acid precipitation.     

Lichen sulphur and lead levels in relation to deposition patterns in Eastern Canada

Marked differences exist between the S and Pb concentration in Cladina ranziferina collected from eastern Canada and the Northwest Territories, Canada. These differences reflected the differing emission/deposition rates in the two regions. The spatial distribution of S and Pb in the lichen from eastern Canada is described in detail. Mean S concentrations ranged from 329 to 959 μg g^?l; Pb concentrations varied in the range 3 to 21 μg g^?l. A regional gradient in lichen S concentrations was evident with the highest concentrations being found in central and north-central Ontario and the lowest in Newfoundland. A regional gradient for Pb was apparent but was not as well defined as that for S. The regional distribution of S illustrated by the lichen agreed with another indirect measurement of S deposition. Lichen S concentrations correlated with measured wet sulphate deposition.     

Frequency distributions for durations and volumes of rainfalls in the Eastern United States in relation to acidic precipitation

A significant percentage (between 17 and 40%) of all showers recorded on Long Island, NY, Urbana, IL, Franklin, NC, and Seaside Park, NJ, had durations less than 20 min. Similarly, a large percentage had durations less than 40 min (50, 46, and 32% for 3 yr at Urbana, IL, 65% at Coral Gables, FL, 50% at Franklin, NC, and 54% at Seaside Park, NJ). When all data from the six growing seasons were pooled, over 88% of all rainfalls were less than 160 min. Similar results were observed when volume measurements were made. Between 38 and 57% of all recorded showers had less than 1 mm at all five stations in the eastern United States. When all data were pooled, over 65% of all rainfalls were less than 3 mm. These data demonstrate that plant foliage is wetted during the growing season by numerous showers which are of short duration and low volume.     

Inter-regional comparison of patterns and trends in surface water acidification across the United States

Temporal trends in acid-base chemistry are reported for surface waters in 6 regions of the United States. The lakes and streams are low ANC, dilute systems, selected to represent acid-sensitive aquatic resources in the 6 regions. The predominant trends observed were decreases in lake and stream SO₄ ^2? concentrations in sites east of the Mississippi River, and increases in NO₃ ^? in the Adirondack lake and Catskill stream sites (both located in eastern New York State). Correlations of trend results from all sites with other factors indicated that trends in precipitation volume were highly correlated with the observed trend patterns. From the surface water trend results, three distinct clusters were identified that corresponded to three trend patterns: ‘dilution,’ ‘recovery,’ and ‘acidification.’ These were distributed across the LTM regions, with no particular geographic patterns.     

An analysis of spatial variability of the dominant ions in precipitation in the eastern United States

Data of the Multistate Atmospheric Power Production Pollution Study (MAP3S) and the National Atmospheric Deposition Program (NADP) were utilized to develop wet deposition spatial distribution patterns for the eastern United States for 1979. The ions of SO₄ ^?, NO₃ ^?, H⁺, and NH₄ ⁺ were selected for study since they are the most prominent ones found in precipitation. Total wet deposition for 1979 was normalized to one centimeter of precipitation and objectively analyzed using the Synagraphic Mapping System (SYMAP) technique. Gradients of SO₄ ^? and NO₃ ^? were found to be essentially uniform, both to the east and west of the major pollution regions. An increased gradient in normalized deposition for SO₄ ^?, NO₃ ^?, and H⁺ was found in the Appalachian Mountain region. Estimates of total wet deposition were obtained by using the normalized deposition values in conjunction with precipitation as reported by the National Climatic Center. SYMAP analyses of the estimated total wet deposition were localized in nature due to precipitation variations between sites.     

Atlantic salmon resources in the Northeastern United States and the potential effects of acidification from atmospheric deposition

The Atlantic salmon (Salmo salar) was formerly abundant in northeast coastal rivers in the United States from the Canadian border to the Connecticut River, and possibly as far south as the Delaware River. It was eliminated from most of its former range by a combination of overfishing, construction of dams impassable to migrating fish, and municipal and industrial pollution. Reproducing populations are now limited to a few rivers in Maine, but attempts are under way to reintroduce the species to some rivers where populations formerly existed. Most of the native Atlantic salmon rivers are low in acid neutralizing capacity and receive acidic precipitation. The third order streams are not now acidic; however, in some first and second order streams in Maine, pH episodically declines to 4.7 and Al increases to 350 μg g^?1. These conditions could be toxic to sensitive early life history stages of Atlantic salmon. Comparison of chemical conditions in two Maine rivers in 1980–1982 with those in 1969–1970 indicated that the streams have not become more acidic during this interval. Data on the sport catch of Atlantic salmon indicated that populations have generally remained stable or recently increased in the Maine rivers having naturally reproducing populations. The recent increase probably resulted from introductions of hatchery smolts to supplement natural reproduction, and the occurrence of strong year classes in 1978 and 1980. The population in one stream has declined significantly in recent years, but the cause of the decline is probably not related to acidic precipitation. Atlantic salmon resources in the U.S. have apparently not been adversely affected by atmospheric deposition at the present time.     

Atmospheric deposition to remote receptors II. Temporal and spatial variation of inorganic ion species in precipitation over the Ilwas-network

Water, Air, & Soil Pollution - Measurements of SO4 −, NO3 −, Cl−, NH4 +, Ca++, Mg++ Na+, K+, pH, and specific conductance, were made on a precipitation event basis (defined as...     

Agricultural Composting in the United States

In the United States, more farms are composting than municipalities, commercial/institutional establishments, and other private sector groups combined. To obtain an overview of agricultural composting in the United States, industry, government, and university representatives from the top 10 beef and dairy cattle, poultry, and swine producing states were contacted between January and April of 1995. These states represent at least 70 percent of the nation's production of these commodities (except for beef cattle at 52 percent). The representatives provided information about the number of farms composting, the materials composted, composting methods, how the compost is used, and motivating and impeding factors for farms to compost. In addition, information was gathered concerning composting crop residues. In this case, specific applications of crop residue composting were identified and individuals knowledgeable about the applications were contacted for background information.

Note the estimated numbers of composting operations presented here represent a best attempt to quantify the composting activity taking place on various types of farms. In many cases, the numbers are rough estimates, based on the assessments of the representatives contacted in each state. Also, they only include the composting operations in the top 10 producing states. A considerable amount of composting occurs outside of these states. Therefore, Tables 1 and 2 underestimate the number of farms that compost.     

Phosphorus management for sustainable biosolids recycling in the United States

Land-based recycling of processed sewage sludge (biosolids) has traditionally been challenged by concerns over metals, organics, pathogens, odors, and public perception. Nutrient concerns, however, portend even greater challenges, and threaten land application programs in the US. Long-term application of biosolids results in accumulation of soil phosphorus (P) above concentrations needed for optimum crop yields. Water quality impairment associated with accelerated eutrophication is driving the US states to adopt policies and laws to reduce P losses to surface waters from agricultural land. Nearly all states have developed site assessment tools (P indices) to rank fields based on their vulnerability to P loss and to target remedial strategies. Biosolids have not been systematically addressed in most states and sustaining economical biosolids recycling programs will be difficult if policies fail to consider certain critical issues. Soil test P benchmarks should be based upon environmental P loss risk rather than crop response. Policies must recognize the role of mandated buffers in protecting surface water quality. Site indices must account for the sizable differences in P loss potential among biosolids types compared to mineral fertilizers and livestock manures. Finally, agronomic rate calculations must recognize different P fertilizer replacement values among biosolids products. Deployment of P management regulations for biosolids lacking scientifically defensible strategies in these areas will adversely affect land-based recycling. Sustainability requires additional research and intentional inclusion of biosolids in implementation of evolving P management policies.     

Pollutant wet deposition mechanisms in precipitation and fog water

Wet deposition of acid-related substances takes place by two processes: precipitation scavenging and fog water impaction/sedimentation on natural surfaces. The relative importance of each deposition pathway depends on the frequency of occurrence of precipitation or fog, the magnitude of the event and the efficiency of pollutant removal by each mechanism. The latter, in turn, is governed by the type of cloud or fog, complex precipitation formation mechanisms and cloud-surface interactions. These factors are examined in the light of our current knowledge. Particular emphasis is placed on how cloud micro-physical as well as air and precipitation measurements, made aloft by aircraft and at the ground, have been used to further our knowledge of wet deposition mechanisms. Future research is needed to quantify the importance of the fog-water deposition pathway in eastern North America to better understand the interaction of gaseous pollutants with cloud and fog-water and to improve our knowledge of pollutant scavenging processes in mesoscale and synoptic weather systems.     

Mortality and morbidity in agriculture in the United States

This article summarizes the trends in agricultural injuries and illnesses in the past decade, as well as the needs for surveillance in the future. Agriculture is one of the most hazardous industries in the U.S. The fatality rate in agriculture remained high (about 22/100,000 workers) through the 1990s. and tractors remained the leading source of death, causing approximately 300 fatalities each year. Non-fatal injuries and illnesses decreased in the employed agricultural worker population. There are no adequate injury and illness data for self-employed farmers and family members to show trends over time. The reported injury rates have been 0.5 to 16.6/100 workers, based on the source of information. Many studies have shown high rates of respiratory and musculoskeletal symptoms, hearing loss, and skin disorders in agriculture. The overall cancer rate is lower; however, certain cancers are elevated in farmers. Surveillance information has not improved significantly in the past decade; however, many studies have provided more insight into the prevalence, incidence, and risk factors for injury and illness. Further efforts are needed to better define the populations at risk, including farmers and ranchers, family members, workers, migrant and seasonal workers, and others exposed to farm hazards. Fatalities are well documented, and it is important to continue existing surveillance in the future. Surveillance systems should be developed to collect information on agriculture-related non-fatal injuries and illnesses.     

Conservation of Lepidoptera in the United States

The need to conserve United States populations of Lepidoptera has been recognised for a century, but intensive programmes to do so have only recently come into being. The evolution of the butterfly and moth conservation movement in the United States is followed from the earliest instances to the present state of progress. The origin and growth of the Xerces Society as the chief body for terrestrial arthropod conservation in America are described. Currently, ecological research and political action aimed at specific lepidopteran protection issues are under way. Several of these are examined and the most acute needs for further study and action indicated. Habitat alteration emerges dramatically as the chief problem in the decline of butterfly and moth populations. The relative importance of pesticides and overcollecting is discussed and reinforces the conclusion that the habitat is paramount. Introductions of organisms for purposes of conservation likewise receive consideration, showing this strategy to be problematical and subject to careful review prior to its use. The various levels of government as well as private bodies and individuals have distinct roles in insect conservation. Greater public awareness of beneficial insects must precede optimal effectiveness of conservation schemes. The appointment of an official federal insect conservator is announced along with his initial proposal for endangered species listings for certain North American butterflies. The prognosis for a national programme is suggested. Lepidoptera conservation in the United States has become a fully fledged movement with numerous successes and with many difficult problems to face. The situation is viewed with immediate alarm but cautious long-term optimism as well.     

Effects of deep tillage and profile modification on soil properties,root growth,and crop yields in the United States and Canada

Unfavorable conditions of soil profiles, through their adverse effects on the growth, proliferation, and activity of roots, may severely limit the yield of crops at some locations in the United States and Canada. A review of the literature showed that deep tillage and modification of soils having unfavorable profiles may increase crop production by providing larger, more favorable zones of soil for the growth, proliferation, and activity of roots. The improved conditions may result from disrupting dense, high-strength horizons; leaching or burying salts or toxic materials; increasing the capacity of sandy soils to retain water; and reducing the erodibility of soil. When the horizons causing problems were adequately disrupted or altered, yields of crops were generally increased. Benefits from the treatments were greater when precipitation or irrigation were limited than when they were adequate. There are many soils on which no benefits can be expected from deep tillage and profile modification.