Environmental impacts of training activities at an air weapons range

Within Canada, it has been recognized in the last decade that military training activities may have impacts on the environmental quality of training ranges. However, impacts of activities specific to Air Force Bases have not yet been intensely documented. A hydrogeological study was accomplished at the Cold Lake Air Weapons Range, Alberta, to evaluate the environmental impacts of using bombs, rockets, strafing, and open burning/open detonation (OB/OD) on the quality of soil, ground water, surface water, and lake sediments. Samples were analyzed for metals, anions, ammonium perchlorate (NH(4)ClO(4)), and energetic materials (EM). It was found that training activities did not result in measured values being exceeded on the basis of guidance values for surface water and lake sediments. Contamination by metals was mostly limited to soils, and some metals may be related to the use of bombs (Cd, Cu, Pb), strafe (Cu), and rockets (As, Ba, Cd, Cr, Cu, Fe, Ni, Pb, U, V, Zn). TNT (2,4,6-trinitrotoluene) was the main EM found in soils, while RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) was more common in ground water. Both are related to live bombing, while nitroglycerine (NG) is related to rocket use and was detected in soils only. Aluminum, nitrate, and ammonium perchlorate detected in ground water may be related to live bombing or rockets. OB/OD operations resulted in the presence of various EM in soils, and of perchlorate and nitrate in ground water. Contamination by metals and explosives in soils was localized around the targets and varied significantly in time; however, in ground water it was more constant and may persist for a period of several years after a target has been removed.     

Nitrogen fertilizer form and associated nitrate leaching from cool-season lawn turf

Various N fertilizer sources are available for lawn turf. Few field studies, however, have determined the losses of nitrate (NO(3)-N) from lawns receiving different formulations of N fertilizers. The objectives of this study were to determine the differences in NO(3)-N leaching losses among various N fertilizer sources and to ascertain when losses were most likely to occur. The field experiment was set out in a completely random design on a turf typical of the lawns in southern New England. Treatments consisted of four fertilizer sources with fast- and slow-release N formulations: (i) ammonium nitrate (AN), (ii) polymer-coated sulfur-coated urea (PCSCU), (iii) organic product, and (iv) a nonfertilized control. The experiment was conducted across three years and fertilized to supply a total of 147 kg N ha(-1) yr(-1). Percolate was collected with zero-tension lysimeters. Flow-weighted NO(3)-N concentrations were 4.6, 0.57, 0.31, and 0.18 mg L(-1) for AN, PCSCU, organic, and the control, respectively. After correcting for control losses, average annual NO(3)-N leaching losses as a percentage of N applied were 16.8% for AN, 1.7% for PCSCU, and 0.6% for organic. Results indicate that NO(3)-N leaching losses from lawn turf in southern New England occur primarily during the late fall through the early spring. To reduce the threat of NO(3)-N leaching losses, lawn turf fertilizers should be formulated with a larger percentage of slow-release N than soluble N.     

Spatial and temporal trends of nitrate,chloride, and bromide concentration in an alluvial aquifer,North‐Central Texas,USA

The Seymour aquifer consists of unconfined outcrops of sand and gravel in a semiarid, agricultural region of north‐central Texas in the United States of America. Most water samples collected from the aquifer in 2015 had nitrate concentrations above the drinking water standard of 44.3 milligrams per liter (mg/L). Generally, areas with high nitrate concentration in 2010 remained high in 2015, although the median dropped by 3.9 mg/L. The largest decreases in nitrate concentration—up to 97 mg/L (60%)—were observed in wells with depths less than the median of 13.1 meters (m). However, other wells, including depths above and below the median, showed increases in nitrate concentration of up to 40 mg/L (42%). In 2015, chloride concentrations in six wells exceeded the secondary contaminant level of 250 mg/L, and one well had a chloride concentration of 1,810 mg/L. Past and ongoing agricultural practices, including cultivation of native grassland, application of fertilizer, and irrigation with nitrate‐contaminated groundwater, help sustain overall high nitrate concentrations within the aquifer. Local conditions governing nitrogen inputs and dilution result in significant improvement or worsening of the nitrate problem over relatively short timeframes. The pumping of groundwater from the aquifer may facilitate mixing with groundwater of increased salinity that has been affected by the dissolution of evaporites in underlying Permian bedrock.     

Nitrate Dynamics in Two Streams Impacted by Wastewater Treatment Plant Discharge: Point Sources or Sinks?

We examined nitrate processing in headwater stream reaches downstream of two wastewater treatment plant outfalls during low streamflow. Our objectives were to quantify nitrate mass flux before and after effluent discharge and to use field and laboratory techniques to assess the mechanism of nitrate uptake. Microcosm experiments were utilized to determine the location of nitrate processing, and molecular biomarkers were used to detect and quantify microbial denitrification. At one site, downstream nitrate mass flux was significantly (p = 0.01) lower than sum of upstream and wastewater effluent fluxes, indicating rapid stream assimilation of incoming nitrate in the vicinity of the point source. Microcosm experiments supported the theory that nitrate processing occurs in sediments. Molecular assays for denitrifcation‐associated functional genes nosZ, nirS, and nirK, provided evidence that effluent contained enriched denitrifying communities relative to ambient stream water. Nitrate loss at the site with greater uptake was correlated with sulfate loss (p < 0.01; r² = 0.86), suggesting a possible link between sulfate reducing bacteria and denitrifying bacterial communities. Results suggest there is an opportunity to better understand nitrate dynamics in cases where point sources may act as point sinks under specific sets of conditions.     

Physicochemical characterization of hydroxyapatite and its application towards removal of nitrate from water

A laboratory study was conducted to investigate the efficiency of hydroxyapatite (HAP) towards removal of nitrate from synthetic nitrate solution. In the present research HAP synthesized from egg-shell was characterized using SEM, XRD, FTIR and TGA–DSC. The removal of nitrate was 96% under neutral conditions, using 0.3 g of adsorbent in 100 mL of nitrate solution having an initial concentration of 100 mg/L. An adsorption kinetic study revealed that the adsorption process followed first order kinetics. Adsorption data were fitted to a linearly transformed Langmuir isotherm with correlation coefficient (R²) > 0.98. Thermodynamic parameters were also calculated to study the effect of temperature on the removal process. In order to understand the adsorption type, equilibrium data were tested with the Dubinin–Radushkevich isotherm. The process was rapid and equilibrium was established within the first 40 min.     

Understanding the impact of waste disposal sites on soil quality for agricultural production: A case study of the Kiteezi landfill,Uganda

Leachate from waste disposal sites (WDS) can significantly affect the soil physical, chemical and biological qualities, reducing soil health and agricultural productivity. However, there is a paucity of data on soil quality for understanding soil health impact due to WDS in Uganda. This study's aim was to understand, using the Kiteezi landfill site, how WDS impact soil properties. Soil samples were collected over 4 months in and around the landfill from three locations, and the soil quality data of the nearby area were used as baseline data for assessing the impact on soil due to WDS in the area. There were significant increases in the concentration of all studied parameters at the landfill except total N. The concentrations of ammonium (14.84 ± 1.76 mg/kg), nitrate (127.96 ± 18.36 mg/kg), and pH (7.8) were above the optimum levels. The levels of available P (181.4 ± 28.9 mg/kg) and exchangeable bases; K (2.23 ± 0.24 mg/kg), Na (1.17 ± 0.14 mg/kg), Mg (3.35 ± 0.3 mg/kg) and Ca (14 ± 1.1 mg/kg) cmol (+)/kg were optimal for plant growth. The calculated CEC of 20.75 cmol (+)/kg) showed that soils have a good potential to supply plant nutrients. Heavy metal levels were still below the permissible limit. Hence, the study shows that although WDS may contribute to the increase of soil fertility, they can potentially reduce the overall productivity of soil by increasing nutrient levels beyond optimum levels.     

Nitrate distributions and source identification in the Abbotsford-Sumas Aquifer,northwestern Washington State

The Abbotsford-Sumas Aquifer is a shallow, predominantly unconfined aquifer that spans regions in southwestern British Columbia, Canada and northwestern Washington, USA. The aquifer is prone to nitrate contamination because of extensive regional agricultural practices. A 22-month ground water nitrate assessment was performed in a 10-km2 study area adjacent to the international boundary in northwestern Washington to examine nitrate concentrations and nitrogen isotope ratios to characterize local source contributions from up-gradient sources in Canada. Nitrate concentrations in excess of 10 mg nitrate as nitrogen per liter (mg N L(-1)) were observed in ground water from most of the 26 domestic wells sampled in the study area, and in a creek that dissects the study area. The nitrate distribution was characteristic of nonpoint agricultural sources and consistent with the historical documentation of agriculturally related nitrate contamination in many parts of the aquifer. Hydrogeologic information, nitrogen isotope values, and statistical analyses indicated a nitrate concentration stratification in the study area. The highest concentrations (> 20 mg N L(-1)) occurred in shallow regions of the aquifer and were linked to local agricultural practices in northwestern Washington. Nitrate concentrations in excess of 10 mg N L(-1) deeper in the aquifer (> 10 m) were related to agricultural sources in Canada. The identification of two possible sources of ground water nitrate in northwestern Washington adds to the difficulty in assessing and implementing local nutrient management plans for protecting drinking water in the region.     

NITRATE TRANSFORMATIONS IN SOUTHERN ONTARIO STREAM SEDIMENTS1

The transformation of nitrate was investigated in diverse stream sediments from six areas of Southern Ontario, Canada. Laboratory Experiments conducted with intact 0-5 cm depth sediment cores overlain with aerated 5 mg/l nitrate-N solution reveald considerable nitrate depletion during a six-day period as a resuit of denitrification and nitrate reduction to ammonium. Nitrification and ammonification also occurred simultaneously with nitrate reduction in many stream sediments. Mixed 0-5 cm depth sediments collected from 81 stream sites were used to examine the relationship between microbial nitrate removal and sediment characteristics. Rates of nitrate-N loss from aerated 5 mg/l nitrate-N solutions overlying these sediments ranged between 11 and 171 mg/m²/day for a 24-hour incubation period. Rates of nitrate loss for the 24-hour period exhibited a significant positive correlation (r=0.72) with sediment ammonium content. Organic carbon, total nitrogen and sediment texture also had significant but weak correlations with nitrate loss.     

Effects of gas flaring on blood parameters and respiratory system of laboratory mice, <Emphasis Type="Italic">Mus musculus</Emphasis>

In order to evaluate the potential harmful effects of gas flaring on mammals, albino mice, Mus musculus, were exposed to gas flares for 8 weeks under laboratory conditions. The effect of gas flaring on blood parameters includes a reduction in white blood cell counts among mice exposed to 8-h daily of gas flaring when compared to control mice. The red blood cells also showed varied abnormalities such as stacked erythrocytes (rouleaux formation), crenated (spicule) cells and teardrop cells (dacrocytes). The detection of the increasing level of eosinophils in the blood of mice exposed to gas flares was observed to be indicative of a degenerative disease condition and usefulness as a good marker of pollution for monitoring, and early detection of adverse effects of gas flares was recommended. Histopathological examination of the lungs of exposed mice revealed distortions in the segmental bronchus and alveoli of the respiratory organ, with interspersed brown pigments and polymorphonuclear cells, which were absent in the controls. The environmental implications including the health hazards posed by the exposure of mammals to gas flares in crude oil production areas were discussed.     

Iowa Statewide Stream Nitrate Load Calculated Using In Situ Sensor Network

Various techniques exist to estimate stream nitrate loads when measured concentration data are sparse. The inherent uncertainty associated with load estimation, however, makes tracking progress toward water quality goals more difficult. We used high‐frequency, in situ nitrate sensors strategically deployed across the agricultural state of Iowa to evaluate 2016 stream concentrations at 60 sites and loads at 35 sites. The generated data, collected at an average of 225 days per site, show daily average nitrate‐N yields ranging from 12 to 198 g/ha, with annual yields as high as 53 kg/ha from the intensely drained Des Moines Lobe. Thirteen of the sites that capture water from 82.5% of Iowa's area show statewide nitrate‐N loading in 2016 totaled 477 million kg, or 41% of the load delivered to the Mississippi–Atchafalaya River Basin (MARB). Considering the substantial private and public investment being made to reduce nitrate loading in many states within the MARB, networks of continuous, in situ measurement devices as described here can inform efforts to track year‐to‐year changes in nitrate load related to weather and conservation implementation. Nitrate and other data from the sensor network described in this study are made publicly available in real time through the Iowa Water Quality Information System.     

Sources and transformations of nitrogen compounds along the Lower Jordan River

The Lower Jordan River is located in the semiarid area of the Jordan Valley, along the border between Israel and Jordan. The implementation of the water sections of the peace treaty between Israel and Jordan and the countries' commitment to improve the ecological sustainability of the river system require a better understanding of the riverine environment. This paper investigates the sources and transformations of nitrogen compounds in the Lower Jordan River by applying a combination of physical, chemical, isotopic, and mathematical techniques. The source waters of the Lower Jordan River contain sewage, which contributes high ammonium loads to the river. Ammonium concentrations decrease from 20 to 0-5 mg N L(-1) along the first 20 km of the Lower Jordan River, while nitrate concentrations increase from nearly zero to 10-15 mg N L(-1), and delta(15)N (NO(3)) values increase from less than 5 per thousand to 15-20 per thousand. Our data analysis indicates that intensive nitrification occurs along the river, between 5 and 12 km from the Sea of Galilee, while further downstream nitrate concentration increases mostly due to an external subsurface water source that enters the river.     

Batch sorption dynamics and equilibrium for the removal of lead ions from aqueous phase using activated carbon developed from coffee residue activated with zinc chloride

Lignocellulosic materials are good precursors for the production of activated carbon. In this work, coffee residue has been used as raw material in the preparation of powder activated carbon by the method of chemical activation with zinc chloride for the sorption of Pb(II) from dilute aqueous solutions.The influence of impregnation ratio (ZnCl₂/coffee residue) on the physical and chemical properties of the prepared carbons was studied in order to optimize this parameter. The optimum experimental condition for preparing predominantly microporous activated carbons with high pore surface area (890 m²/g) and micropore volume (0.772 cm³/g) is an impregnation ratio of 100%. The developed activated carbon shows substantial capability to sorb lead(II) ions from aqueous solutions and for relative impregnation ratios of 75 and 100%, the maximum uptake is practically the same. Thus, 75% represents the optimal impregnation ratio.Batch experiments were conducted to study the effects of the main parameters such as contact time, initial concentration of Pb(II), solution pH, ionic strength and temperature. The maximum uptake of lead(II) at 25 °C was about 63 mg/g of adsorbent at pH 5.8, initial Pb(II) concentration of 10 mg/L, agitation speed of 200 rpm and ionic strength of 0.005 M. The kinetic data were fitted to the models of pseudo-first order and pseudo-second order, and follow closely the pseudo-second order model. Equilibrium sorption isotherms of Pb(II) were analyzed by the Langmuir, Freundlich and Temkin isotherm models. The Freundlich model gives a better fit than the others.Results from this study suggest that activated carbon produced from coffee residue is an effective adsorbent for the removal of lead from aqueous solutions and that ZnCl₂ is a suitable activating agent for the preparation of high-porosity carbons.     

Estimation of Nonpoint Source Nitrate Concentrations in Indiana Rivers Based on Agricultural Drainage in the Watershed

Subsurface tile‐drained agricultural fields are known to be important contributors to nitrate in surface water in the Midwest, but the effect of these fields on nitrate at the watershed scale is difficult to quantify. Data for 25 watersheds monitored by the Indiana Department of Environmental Management and located near a U.S. Geological Survey stream gage were used to investigate the relationship between flow‐weighted mean concentration (FWMC) of nitrate‐N and the subsurface tile‐drained area (DA) of the watershed. The tile DA was estimated from soil drainage class, land use, and slope. Nitrate loads from point sources were estimated based on reported flows of major permitted facilities with mean nitrate‐N concentrations from published sources. Linear regression models exhibited a statistically significant relationship between annual/monthly nonpoint source (NPS) nitrate‐N and DA percentage. The annual model explained 71% of the variation in FWMC of nitrate‐N. The annual and monthly models were tested in 10 additional watersheds, most with absolute errors within 1 mg/l in the predicted FWMC. These models can be used to estimate NPS nitrate for unmonitored watersheds in similar areas, especially for drained agricultural areas where model performance was strongest, and to predict the nitrate reduction when various tile drainage management techniques are employed.     

Application of a chemically modified green macro alga as a biosorbent for phenol removal

Phenol and substituted phenols are toxic organic pollutants present in tannery waste streams. Environmental legislation defines the maximum discharge limit to be 5–50 ppm of total phenols in sewers. Thus the efforts to develop new efficient methods to remove phenolic compounds from wastewater are of primary concern. The present work aims at the use of a modified green macro alga (Caulerpa scalpelliformis) as a biosorbent for the removal of phenolic compounds from the post-tanning sectional stream. The effects of initial phenol concentration, contact time, temperature and initial pH of the solution on the biosorption potential of macro algal biomass have been investigated. Biosorption of phenol by modified green macro algae is best described by the Langmuir adsorption isotherm model. Biosorption kinetics of phenol onto modified green macro algal biomass were best described by a pseudo second order model. The maximum uptake capacity was found to be 20 mg of phenol per gram of green macro algae. A Boyd plot confirmed the external mass transfer as the slowest step involved in the biosorption process. The average effective diffusion coefficient was found to be 1.44 × 10⁻⁹ cm²/s. Thermodynamic studies confirmed the biosorption process to be exothermic.     

Constructed Wetland Treatment of Nitrates: Removal Effectiveness and Cost Efficiency

A constructed wetland (CW) was strategically placed to treat nitrates in groundwater as part of a watershed‐based farmer engagement process. Using stream water quality data collected before and after installation, this CW was found to reduce stream concentrations of nitrogen from nitrate (NO₃‐N) during the growing season by about 0.14 mg/l at mean streamflow, a 17% reduction. Based upon realistic ecological and economic assumptions, about 80 kg of NO₃‐N were removed annually by the CW at a cost of around US$30/kg. This per unit cost is at the low range of small wastewater treatment plant costs for nitrates, but higher than the costs of reduced fertilizer application.     

Modeling Nitrate-Nitrogen Load Reduction Strategies for the Des Moines River,Iowa Using SWAT

The Des Moines River that drains a watershed of 16,175 km² in portions of Iowa and Minnesota is impaired for nitrate-nitrogen (nitrate) due to concentrations that exceed regulatory limits for public water supplies. The Soil Water Assessment Tool (SWAT) model was used to model streamflow and nitrate loads and evaluate a suite of basin-wide changes and targeting configurations to potentially reduce nitrate loads in the river. The SWAT model comprised 173 subbasins and 2,516 hydrologic response units and included point and nonpoint nitrogen sources. The model was calibrated for an 11-year period and three basin-wide and four targeting strategies were evaluated. Results indicated that nonpoint sources accounted for 95% of the total nitrate export. Reduction in fertilizer applications from 170 to 50 kg/ha achieved the 38% reduction in nitrate loads, exceeding the 34% reduction required. In terms of targeting, the most efficient load reductions occurred when fertilizer applications were reduced in subbasins nearest the watershed outlet. The greatest load reduction for the area of land treated was associated with reducing loads from 55 subbasins with the highest nitrate loads, achieving a 14% reduction in nitrate loads achieved by reducing applications on 30% of the land area. SWAT model results provide much needed guidance on how to begin implementing load reduction strategies most efficiently in the Des Moines River watershed.     

Nitrogen availability from composts for humid region perennial grass and legume-grass forage production

Perennial forages may be ideally suited for fertilization with slow N release amendments such as composts, but difficulties in predicting N supply from composts have limited their routine use in forage production. A field study was conducted to compare the yield and protein content of a binary legume-grass forage mixture and a grass monocrop cut twice annually, when fertilized with diverse composts. In all three years from 1998-2000, timothy (Phleum pratense L.)-red clover (Trifolium pratense L.) and timothy swards were fertilized with ammonium nitrate (AN) at up to 150 and 300 kg N ha(-1) yr(-1), respectively. Organic amendments, applied at up to 600 kg N ha(-1) yr(-1) in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC), or sewage sludge (SSLC), plus liquid dairy manure (DM). Treatments DM at 150 kg N ha(-1) yr(-1) and CSC at 600 kg N ha(-1) yr(-1) produced cumulative timothy yields matching those obtained for inorganic fertilizer. Apparent nitrogen recovery (ANR) ranged from 0.65% (SSLC) to 15.1% (DMC) for composts, compared with 29.4% (DM) and 36.5% (AN). The legume component (approximately 30%) of the binary mixture acted as an effective "N buffer" maintaining forage yield and protein content consistently higher, and within a narrower range, across all treatments. Integrating compost utilization into livestock systems that use legume-grass mixtures may reduce the risk of large excesses or deficits of N, moderate against potential losses in crop yield and quality, and by accommodating lower application rates of composts, reduce soil P and K accumulation.     

饮用水中高氯酸盐污染现状与去除技术的综述

高氯酸盐作为强氧化剂，在广泛的应用中造成了严重的环境污染，并会在人体富集，当在人体内含量超过0．0007mg／kg人体体重，相当于饮用水中的浓度为24．5μg／L时，就会对健康造成影响，尤其会破环甲状腺机能。美国、日本等国已开始采取措施加强对高氯酸盐的控制，我国许多水源也受到此污染但尚未引起重视。本文分析了饮用水中高氯酸盐的物理化学性质及毒理特性，对环境的污染状况以及目前常用的去除技术，其中以生物处理和离子交换膜生物反应器较为有效。     

Bioremediation of residual fertilizer nitrate: I. Laboratory demonstration of an on-farm in situ pollution control system

This exploratory laboratory study was undertaken to develop and test an in situ bioremediation system intended to point the way toward a possible field application. The proposed method uses a water table management (WTM) system to deliver nutrients or other amendments to subsoil microorganisms for biostimulation and subsequent biodegradation of pollutants in the saturated and unsaturated zones of the soil. The study was carried out on packed soil columns and bioremediation of residual fertilizer nitrate was attempted. Different levels of organic carbon supplement (glucose C) were introduced into these columns via subirrigation in order to supplement the readily available organic carbon levels in the soil. The study was carried out in two experimental setups. The first setup investigated (i) the effect of addition of a high (970 mg L(-1)) and a low (120 mg L(-1)) glucose C level and (ii) the efficacy of using the subirrigation system as a method for nutrient delivery in bioremediation of leached nitrate. This setup was monitored with time, depth, and with reference to the nitrate residue in the soil solution. Leached nitrate was denitrified to less than 10 mg L(-1) nitrate N at both glucose levels. The second setup investigated the effect of a range of low levels of glucose C on nitrate decontamination, soil pH, and total microbial count in order to find out an optimal glucose C level that reduced the most nitrate and maintained the pH homeostasis of soil.     

Minimizing life-cycle costs of gun propellant selection through model-based decision making: a case study in environmental screening and performance testing

The work presented here demonstrates the first phases of a newly-proposed gun propellant formulation process that will minimize life-cycle costs through science-based design. This new approach to gun propellant formulation proposes maximal use of modeling and simulation in the earliest phases of the developmental cycle to screen candidate formulations, resulting in the elimination of probable poor performers and the identification of the most promising candidates for further study and testing. The screening and identification of promising candidate formulations is demonstrated in the study presented here under the assumption of a specific weapon platform and user requirements. The process of selecting a propellant for the assumed gun system application has been distilled into a series of measurable steps leading from a set of candidate materials, through logical and numerical filters, to a shorter list of energetic materials demonstrated as viable choices for the weapon platform. Environmental filtering and performance modeling are used to screen propellants through a well-defined sequence of tests designed to weed out materials that do not meet standards in terms of safety, energy, or manufacturability. Because much of the testing is performed by computer modeling, the gun systems and energetic materials need not be present (nor even existent) in order to be described and matched against performance requirements for future applications. The calculations presented here demonstrate that utilizing computer models in the early developmental stages of the formulation process rather than physical testing produces enormous savings in labor, material, and environmental costs, along with a tremendous reduction in the time required to select a "best candidate" propellant.