Characteristics of natural salt licks located in the Colombian Amazon foothills

Salt licks are key places for the ecological dynamics of wildlife communities around the world and are locations where animals develop geophagical behaviours. Geophagy is a method for animals to supplement their diets or facilitate their digestive processes and is related to the health of individuals and populations. This study characterises a series of salt licks located in the Colombian Amazon foothills and describes their structural, mineralogical and physicochemical properties, as well as the fauna that visit these locations. The results are analysed in reference to the geological characteristics of the study area and in relation to the role of the salt lick in the nutritional ecology of the Amazonian fauna. Located in the study area are two types of salt licks that are significantly different in composition. These salt licks are located in an area where young geological materials have been exposed. The characteristics of the salt licks supports the hypothesis that they are used to solve nutritional problems that result from herbivorous diets. The clear importance of salt licks in the ecology of several Amazonian animal species emphasises the need to prioritise conservation areas by maximising the complementarities of salt lick sites.     

Protected area characteristics that help waterbirds respond to climate warming

Protected area networks help species respond to climate warming. However, the contribution of a site's environmental and conservation-relevant characteristics to these responses is not well understood. We investigated how composition of nonbreeding waterbird communities (97 species) in the European Union Natura 2000 (N2K) network (3018 sites) changed in response to increases in temperature over 25 years in 26 European countries. We measured community reshuffling based on abundance time series collected under the International Waterbird Census relative to N2K sites’ conservation targets, funding, designation period, and management plan status. Waterbird community composition in sites explicitly designated to protect them and with management plans changed more quickly in response to climate warming than in other N2K sites. Temporal community changes were not affected by the designation period despite greater exposure to temperature increase inside late-designated N2K sites. Sites funded under the LIFE program had lower climate-driven community changes than sites that did not received LIFE funding. Our findings imply that efficient conservation policy that helps waterbird communities respond to climate warming is associated with sites specifically managed for waterbirds.     

Assessment of diesel particulate matter exposure in the workplace: freight terminals

A large study has been undertaken to assess the exposure to diesel exhaust within diesel trucking terminals. A critical component of this assessment is an analysis of the variation in carbonaceous particulate matter (PM) across trucking terminal locations; consistency in the primary sources can be effectively tracked by analyzing trends in elemental carbon (EC) and organic molecular marker concentrations. Ambient samples were collected at yard, dock and repair shop work stations in 7 terminals in the USA and 1 in Mexico. Concentrations of EC ranged from 0.2 to 12 microg m(-3) among the terminals, which corresponds to the range seen in the concentration of summed hopanes (0.5 to 20.5 ng m(-3)). However, when chemical mass balance (CMB) source apportionment results were presented as percent contribution to organic carbon (OC) concentrations, the contribution of mobile sources to OC are similar among the terminals in different cities. The average mobile source percent contribution to OC was 75.3 +/- 17.1% for truck repair shops, 65.4 +/- 20.4% for the docks and 38.4 +/- 9.5% for the terminal yard samples. A relatively consistent mobile source impact was present at all the terminals only when considering percentage of total OC concentrations, not in terms of absolute concentrations.     

PM composition and source reconciliation in Mexico City

PM_2.5 and PM₁₀ were collected during 24-h sampling intervals from March 1st to 31st, 2006 during the MILAGRO campaign carried out in Mexico City's northern region, in order to determine their chemical composition, oxidative activity and the estimation of the source contributions during the sampling period by means of the chemical mass balance (CMB) receptor model. PM_2.5 concentrations ranged from 32 to 70 μg m⁻³ while that of PM10 did so from 51 to 132 μg m⁻³. The most abundant chemical species for both PM fractions were: OC, EC, SO₄²⁻, NO₃⁻, NH₄⁺, Si, Fe and Ca. The majority of the PM mass was comprised of carbon, up to about 52% and 30% of the PM2.5 and PM10, respectively. PM2.5 constituted more than 50% of PM10. The redox activity, assessed by the dithiothreitol (DTT) assay, was greater for PM_2.5 than for PM₁₀, and did not display significant differences during the sampling period. The PM_2.5 source reconciliation showed that in average, vehicle exhaust emissions were its most important source in an urban site with a 42% contribution, followed by re-suspended dust with 26%, secondary inorganic aerosols with 11%, and industrial emissions and food cooking with 10% each. These results had a good agreement with the Emission Inventory. In average, the greater mass concentration occurred during O₃S that corresponds to a wind shift initially with transport to the South but moving back to the North. Taken together these results show that PM chemical composition, oxidative potential, and source contribution is influenced by the meteorological conditions.     

Pulverized coal stream ignition delay under conventional and oxy-fuel combustion conditions

The coal stream ignition process is critical to the performance of modern pulverized coal burners, particularly when operating under novel conditions such as experienced in oxy-fuel combustion. However, experimental studies of coal stream ignition are lacking, and recent modeling efforts have had to rely on comparisons with a single set of experiments in vitiated air. To begin to address this shortfall, we have conducted experiments on the ignition properties of two U.S. and two Chinese coals in a laminar entrained flow reactor. Most of the measurements focused on varying the coal feed rate for furnace temperatures of 1230–1320 K and for 12–20 vol.% O₂ in nitrogen. The influence of coal feed rate on ignition with a carbon dioxide diluent was also measured for 20 vol.% O₂ at 1280 K. A second set of measurements was performed for ignition of a fixed coal feed rate in N₂ and CO₂ environments at identical furnace temperatures of 1200 K, 1340 K, and 1670 K. A scientific CCD camera equipped with a 431 nm imaging filter was used to interrogate the ignition process. Under most conditions, the ignition delay decreased with increasing coal feed rate until a minimum was reached at a feed rate corresponding to a particle number density of approximately 4 × 10⁹ m^?3 in the coal feed pipe. This ignition minimum corresponds to a cold flow group number, G, of ～0.3. At higher coal feed rates the ignition delay increased. The ignition delay time was shown to be very sensitive to (a) the temperature of the hot coflow into which the coal stream is introduced, and (b) the coal particle size. The three high volatile bituminous coals showed nearly identical ignition delay as a function of coal feed rate, whereas the subbituminous coal showed slightly greater apparent ignition delay. Bath gas CO₂ content was found to have a minor impact on ignition delay.