Comparison of PM2.5 carbon measurement methods in Hong Kong, China

Samples from Hong Kong, China, were analyzed for organic carbon (OC), elemental carbon (EC), and total carbon (TC) by three thermal protocols (low-temperature IMPROVE and high-temperature STN and NIOSH) and two optical monitoring methods: reflectance and transmittance. Good agreement (+/-10%) for TC among the three protocols was observed for sample loadings of 1-55 microg m(-3). The two protocols using a reflectance pyrolysis correction showed best agreement for EC, with <20% differences found for approximately 80% of the samples. Hong Kong has a large diesel fleet, and for some heavily loaded samples the light transmittance was too low for quantitative detection, resulting in large uncertainties in the OC/EC split based on transmittance. Hong Kong experienced OC levels similar to those at US sites, but has much higher EC concentrations. OC/EC ratios range from 2 to 5 at two US sites and from 0.2 to 1.2 at three Hong Kong sites.     

Chapter three: methodology of exposure modeling

In this chapter, the concept of exposure assessment and its evolution is introduced, and evaluated by critically appraising the pertinent literature as it applies to exposures to Particulate Matter (PM). Exposure measurement or estimation methodologies and models are reviewed. Three exposure/measurement methodologies are assessed. Estimation methods focus on source evaluation and attribution, sources include those outdoors and indoors as well as in occupational and in-transit environments. Fate and transport models and their inputs are addressed to estimate concentrations outdoors and indoors; source attribution techniques help focus on the contributing sources. Activity pattern techniques are also reviewed and their use in exposure models to estimate inhalation exposure to PM is presented. Deterministic, regression and other stochastic models of exposure to PM are reviewed and evaluated. Strengths, limitations, assumptions and affirmations of the use of exposure assessment as an integral component of risk assessment and risk management are discussed in the conclusions and discussions section of this work.     

PM2.5 chemical source profiles for vehicle exhaust, vegetative burning, geological material, and coal burning in Northwestern Colorado during 1995

PM_2.5 (particles with aerodynamic diameters less than 2.5 μm) chemical source profiles applicable to speciated emissions inventories and receptor model source apportionment are reported for geological material, motor vehicle exhaust, residential coal (RCC) and wood combustion (RWC), forest fires, geothermal hot springs; and coal-fired power generation units from northwestern Colorado during 1995. Fuels and combustion conditions are similar to those of other communities of the inland western US. Coal-fired power station profiles differed substantially between different units using similar coals, with the major difference being lack of selenium in emissions from the only unit that was equipped with a dry limestone sulfur dioxide (SO₂) scrubber. SO₂ abundances relative to fine particle mass emissions in power plant emissions were seven to nine times higher than hydrogen sulfide (H₂S) abundances from geothermal springs, and one to two orders of magnitude higher than SO₂ abundances in RCC emissions, implying that the SO₂ abundance is an important marker for primary particle contributions of non-aged coal-fired power station contributions. The sum of organic and elemental carbon ranged from 1% to 10% of fine particle mass in coal-fired power plant emissions, from 5% to 10% in geological material, >50% in forest fire emissions, >60% in RWC emissions, and >95% in RCC and vehicle exhaust emissions. Water-soluble potassium (K⁺) was most abundant in vegetative burning profiles. K⁺/K ratios ranged from 0.1 in geological material profiles to 0.9 in vegetative burning emissions, confirming previous observations that soluble potassium is a good marker for vegetative burning.     

Second generation chemical mass balance source apportionment of sulfur oxides and sulfate at the Grand Canyon during the Project MOHAVE summer intensive

Receptor-based chemical mass balance (CMB) analysis techniques are designed to apportion species that are conserved during pollutant transport using conserved source profiles. The techniques will fail if non-conservative species (or profiles) are not properly accounted for in the CMB model. The straightforward application of the CMB model developed for Project MOHAVE using regional profiles resulted in a significant under-prediction of total sulfate oxides (SOx, SO2 plus fine particulate sulfate) for many samples at Meadview, AZ. In addition, for these samples the concentration of the inert tracer emitted from the MOHAVE Power Project (MPP), ocPDCH, was also under-predicted. A second-generation model has been developed which assumes that separation of particles and SO2 can occur in the MPP plume during nighttime stable plume conditions. This second-generation CMB model accounts for all SOx present at the various receptor sites. In addition, the concentrations of ocPDCH and the presence of other inert tracers of emission from regional sources are accurately predicted. The major source of SOx at Meadview was the MPP, but the major source of sulfate at this site was the Las Vegas urban area. At Hopi Point in the Grand Canyon, the Baja California region (Imperial Valley and northwestern Mexico) was the major source of both SOx and sulfate.     

On-road vehicle particulate matter and gaseous emission distributions in Las Vegas, Nevada, compared with other areas

During the spring and summer of 2000, 2001, and 2002, gaseous and particulate matter (PM) fuel-based emission factors for approximately 150,000 low-tailpipe, individual vehicles in the Las Vegas, NV, area were measured via on-road remote sensing. For the gaseous pollutants (carbon monoxide, hydrocarbons, and nitrogen oxide), a commercial vehicle emissions remote sensing system (VERSS) was used. The PM emissions were determined using a Lidar-based VERSS. Emission distributions and their shapes were analyzed and compared with previous studies. The large skewness of the distributions is evident for both gaseous pollutants and PM and has important implications for emission reduction policies, because the majority of emissions are attributed to a small fraction of vehicles. Results of this Las Vegas study and studies at other geographical locations were compared. The gaseous pollutants were found to be close to those measured by VERSS in other U.S. cities. The PM emission factors for spark ignition and diesel vehicles are in the range of previous tunnel and dynamometer studies.     

Assessing the efficacy of dredged materials from lake panasoffkee,Florida: Implication to environment and agriculture

BACKGROUND, AIMS AND SCOPE: Current dredged material disposal alternatives have several limitations. Options for dealing with dredged materials include leaving them alone, capping them with clean sediments, placing them in confined facilities, disposing of them at upland sites, treating them chemically, or using them for wetlands creation or other beneficial uses The ability to reuse lake-dredge materials (LDM) for agricultural purposes is important because it reduces the need for offshore disposal and provides an alternative to disposal of the materials in landfills. Often these materials can be obtained at little or no cost to the farmers or landowners. Thus, forage production offers an alternative to waste management since nutrients in the LDM are recycled into crops that are not directly consumed by humans. The objective of this study (Part 2) were to: (1) assess dredge materials from Lake Panasoffkee, Florida as a soil amendment to establish bahiagrass (BG) in a subtropical beef cattle pasture in Sumter County, Florida; and (2) determine the effect of LDM application on the crude protein (CP) and nutrient uptake of BG. This series of two papers aims at providing assessment of the efficacy of lake-dredged materials especially its implication to environment (soil quality, Part 1) and agriculture (forage quality and pasture establishment, Part 2). METHODS: The experimental treatments that were evaluated consisted of different ratios of natural soil (NS) to LDM: LDM0 (100% NS:0% LDM); LDM25 (75% NS:25% LDM); LDM50 (50% NS:50% LDM); LDM75 (25% NS:75% LDM); and LDM100 (0% NS:100% LDM). Bahiagrass plots at its early establishment were cut to a 5-cm stubble height on Julian days 112 and harvested to the same stubble height on Julian days 238 and on Julian days 546 following the double-ring method. Field layout was based on the principle of a completely randomized block design with four replications. Plant samples harvested at 546 Julian days were ground to pass through a 1-mm mesh screen in a Wiley mill. Ground forage was analyzed for crude protein. Ground forage samples were also analyzed for tissue P, K, Ca, Mg, Mn, Cu, Fe, Al, and Mo concentrations using an ICP spectroscopy. The effects of dredged materials addition on forage yield and on crude protein and nutrient uptake that were taken at 546 Julian days were analyzed statistically following the PROC ANOVA procedures. RESULTS AND DISCUSSION: Part 1 of this study demonstrated that the heavy and trace metal contents of LDM were below the probable effect levels and threshold effect levels. As such, the agricultural or livestock industry could utilize these LDM to produce forages. Resuits showed consistently and significantly (p < 0.001) higher BG biomass production and CP from plots amended with LDM than those of BG planted on plots with 0% LDM. Forage yield of BG during its establishment increased linearly (Forage Yield = 1724.3 + 25.64*LDM; R2 = 0.83; p < or = 0.0001) with increasing rates of LDM application. The CP of BG also varied significantly with varying levels of LDM applications. The tissues of BG with 100% LDM had the greatest CP content while the lowest CP content was from the control plots (LDM0). The CP of BG increased linearly with increasing rates of LDM application. The crude protein response to BG application can be described by a linear equation: Crude Protein = 10.38 + 0.052*LDM; R2 = 0.85 p < or = 0.0001. Addition of LDM had increased the levels of Ca by about 1811% when compared with the level of soil Ca among plots with no LDM application. Liming the field could have some direct and indirect effects on the chemical status of the soils. The physiological functions performed by Ca in plants are not clearly defined, but it has been suggested that Ca favors the formation of and increases the protein content of mitochondria. CONCLUSIONS: Beneficial uses of dredged materials from LP, Florida are both economical and environmental. Often these materials can be obtained at little or no cost to the farmers or landowners. Results showed that dredged materials can be used as soil amendments (lime and fertilizer) for early establishment of BG in beef cattle pastures. Environmentally, dredging of sediments that are rich in CaCO3 should restore the 19.4-sq km LP by removing natural sediments from the lake bottom to improve the fishery, water quality, and navigation of the lake. The nutritional uptake of BG grown in unfertile sandy soils of Sumter County was enhanced significantly (p < or = 0.001) by LDM addition. Uptake of TKN, TP, K, Ca, and Mg were remarkably increased as a result of LDM. RECOMMENDATION AND OUTLOOK: Land application of LDM from LP may not only provide substantial benefits that will enhance the environment, community, and society in south Florida, but also in other parts of the world especially those areas with forage-based beef cattle pastures and similar climatic conditions. The heavy and trace metal contents of these materials were below the PEL and TEL (see Part 1). As such, the agricultural or livestock industry could utilize these LDM to produce forages. LDM should be regarded as a beneficial resource, as a part of the ecological system. Although our results have demonstrated the favorable and beneficial effects of added LDM on the early establishment of BG in pasture fields., further studies are still needed not only in pastures of south Florida, but also in other areas with subtropical or tropical climatic conditions to determine whether the environmental and ecological implications of LDM application are satisfied over the longer term.     

An inter-laboratory study to test the ability of amendments to reduce the availability of Cd, Pb, and Zn in situ

An international inter-laboratory research program investigated the effectiveness of in situ remediation of soils contaminated by cadmium, lead and zinc, measuring changes in soil and soil solution chemistry, plants and soil microbiota. A common soil, from mine wastes in Jasper County MO, was used. The soil was pH 5.9, had low organic matter (1.2 g kg(-1) C) and total Cd, Pb, and Zn concentrations of 92, 5022, and 18 532 mg kg(-1), respectively. Amendments included lime, phosphorus (P), red mud (RM), cyclonic ashes (CA), biosolids (BIO), and water treatment residuals (WTR). Both soil solution and NH4NO3 extractable metals were decreased by all treatments. Phytotoxicity of metals was reduced, with plants grown in P treatments having the highest yields and lowest metal concentration (0.5, 7.2 and 406 mg kg(-1) Cd, Pb, and Zn). Response of soil micro-organisms was similar to plant responses. Phosphorus addition reduced the physiologically based extraction test Pb from 84% of total Pb extracted in the untreated soil to 34.1%.     

Somatic Coliphage Profiles of Produce and Environmental Samples from Farms in Northern México

Somatic coliphages were quantified in 459 produce and environmental samples from 11 farms in Northern Mexico to compare amounts of somatic coliphages among different types of fresh produce and environmental samples across the production steps on farms. Rinsates from cantaloupe melons, jalapeño peppers, tomatoes, and the hands of workers, soil, and water were collected during 2011–2012 at four successive steps on each farm, from the field before harvest through the packing facility, and assayed by FastPhage MPN Quanti-tray method. Cantaloupe farm samples contained more coliphages than jalapeño or tomato (p range <0.01–0.03). Across production steps, jalapeños had higher coliphage percentages before harvest than during packing (p = 0.03), while tomatoes had higher coliphage concentrations at packing than all preceding production steps (p range <0.01–0.02). These findings support the use of targeted produce-specific interventions at multiple points in the process of growing and packing produce to reduce the risk of enteric virus contamination and improve food safety during fruit and vegetable production.     

Heavy Metal Toxicity Responses of Two Willow (Salix) Varieties Grown Hydroponically: Development of a Tolerance Screening Test

The E.U. funded BIORENEW project is investigating bioremediation of industrially degraded land using biomass fuel crops, including willow. One of its goals is to develop a rapid screening test to assess the metal tolerance of large numbers of willow varieties. This should reflect how a plant will respond to heavy metals under various field conditions and in the long term. A preliminary experiment tested two varieties of contrasting ability to thrive in metal-contaminated soils. Trees were exposed to a metal cocktail in three different strengths of background solution. An appropriate strength solution (1/4 strength Hoaglands) was identified for differentiating variety performance, based on its effect on the biomass of plant fractions relative to control fractions. This is a response to heavy metals which can be quantified rapidly and simply. The relative performance of the varieties was comparable to their performance in field studies. This test will be used to assess the tolerance of further varieties.