Benthic foraminifera from polluted marine environment of Sulaibikhat Bay (Kuwait)

Quantitative analyses of recent benthic foraminiferal assemblages (living and dead) were carried out on the surface sediments of Sulaibikhat Bay. Marked contrast in foraminiferal assemblages between the shallow tidal mudflats and the deep tidal channel and their relation to the extent of pollution were observed. Cluster analysis of quantitative data on the distribution of foraminiferal tests revealed three assemblages that depend mainly on the intensity of pollution; (1) a highly polluted tidal flat assemblage, (2) normal (or less polluted) mud flat assemblage and, (3) tidal channel and subtidal assemblage. The highly polluted assemblage characterized by a drop in species densities (< 100 tests/20 cm(3) sediment) but with high average diversity (5.8 Yule-Simpson Index). The microfauna of the less polluted flat displays relatively lower diversity (4.6) but high density of tests (47.2% of the total picked tests). The most abundant species of this assemblage is Ammonia tepida, displays its maximum density in this assemblage. Ammonia tepida drops in density from 17.12% to 3.07% in the polluted assemblage. Tidal channel foraminiferal assemblages should normally display lower diversities than those of tidal flats, because tidal current in the channels tend to wash away most nutrient materials. However, this is not the case of the present study area which could be due to environmental setting of the Sulaibikhat Bay in which tidal currents bring in exceptionally high amounts of nutrients from Shatt Al-Arab Estuary and in which the tidal flats are strongly and adversely polluted.     

Examining the temperature dependence of ethanol (E85) versus gasoline emissions on air pollution with a largely-explicit chemical mechanism

The increased use of ethanol in transportation fuels warrants an investigation of its consequences. An important component of such an investigation is the temperature dependence of ethanol and gasoline exhaust chemistry. We use the Master Chemical Mechanism (MCM, version 3.1, LEEDS University) with the SMVGEAR II chemical ordinary differential solver to provide the speed necessary to simulate complex chemistry to examine such effects. The MCM has over 13,500 organic reactions and 4600 species. SMVGEAR II is a sparse-matrix Gear solver that reduces the computation time significantly while maintaining any specified accuracy. Although we use a box model for this study, we determine and demonstrate in a separate study that the speed of the MCM with SMVGEAR II allows the MCM to be modeled in 3-dimensions. We also verified the accuracy of the model in comparison with smog chamber data. We then use the model with species-resolved tailpipe emissions data for E85 (15% gasoline, 85% ethanol fuel blend) and gasoline vehicles to compare the impact of each on nitrogen oxides, organic gases, and ozone as a function of ambient temperature and background concentrations, using Los Angeles in 2020 as a base case. We use two different emissions sets – one is a compilation of exhaust and evaporative data taken near 24 °C and the other from exhaust data taken at ?7 °C – to determine how atmospheric chemistry and emissions are affected by temperature. We include diurnal effects by examining two day scenarios. We find that, accounting for chemistry and dilution alone, the average ozone concentrations through the range of temperatures tested are higher with E85 than with gasoline by ～7 part per billion volume (ppbv) at higher temperatures (summer conditions) to ～39 ppbv at low temperatures and low sunlight (winter conditions) for an area with a high nitrogen oxide (NOx) to non-methane organic gas (NMOG) ratio. The results suggest that E85's effect on health through ozone formation becomes increasingly more significant relative to gasoline at colder temperatures due to the change in exhaust emission composition at lower temperatures. Acetaldehyde and formaldehyde concentrations are also much higher with E85 at cold temperatures, which is a concern because both are considered to be carcinogens. These could have implications for wintertime use of E85. Peroxy acetyl nitrate (PAN), another air pollutant of concern, increases with E85 by 0.3–8 ppbv. The sensitivity of the results to box size, initial background concentrations, background emissions, and water vapor were also examined.     

Broadband UV spectroscopy system used for monitoring of SO2 and NO emissions from thermal power plants

A gas monitoring system based on broadband absorption spectroscopic techniques in the ultraviolet region is described and tested. The system was employed in real-time continuous concentration measurements of sulfur dioxide (SO₂) and nitric oxide (NO) from a 220-ton h^?1 circulating fluidized bed (CFB) boiler in Shandong province, China. The emission coefficients (per kg of coal and per kWh of electricity) and the total emission of the two pollutant gases were evaluated. The measurement results showed that the emission concentrations of SO₂ and NO from the CFB boiler fluctuated in the range of 750–1300 mg m^?3 and 100–220 mg m^?3, respectively. Compared with the specified emission standards of air pollutants from thermal power plants in China, the values were generally higher for SO₂ and lower for NO. The relatively high emission concentrations of SO₂ were found to mainly depend on the sulfur content of the fuel and the poor desulfurization efficiency. This study indicates that the broadband UV spectroscopy system is suitable for industrial emission monitoring and pollution control.     

Behaviour and dynamics of di-ammonium phosphate in bauxite processing residue sand in Western Australia—II. Phosphorus fractions and availability

Background, aim and scope  

Australia is the largest producer of bauxite in the world, with an annual output of approximately 62 million metric dry tons in 2007. For every tonne of alumina, about 2 tonnes of highly alkaline and highly saline bauxite-processing residue are produced. In Western Australia, Alcoa World Alumina, Australia (Alcoa) produces approximately 15 MT of residue annually from its refineries (Kwinana, Pinjarra and Wagerup). The bauxite-processing residue sand (BRS) fraction represents the primary material for rehabilitating Alcoa’s residue disposal areas (RDAs). However, the inherently hostile characteristics (high alkalinity, high salinity and poor nutrient availability) of BRS pose severe limitations for establishing sustainable plant cover systems. Alcoa currently applies 2.7 t ha⁻¹ of di-ammonium phosphate ((NH₄)₂HPO₄; DAP)-based fertiliser as a part of rehabilitation of the outer residue sand embankments of its RDAs. Limited information on the behaviour of the dominant components of this inorganic fertiliser in highly alkaline BRS is currently available, despite the known effects of pH on ammonium (NH₄) and phosphorus (P) behaviour. The aim of this study was to quantify the effects of pH on NH₃ volatilisation and residual nitrogen (N) in BRS following DAP applications.     

An ecological risk assessment model for a pulsed contaminant emission into a wetland channel flow

As a continuation of the modelling on ecological degradation and hydraulic dispersion of pollutant emission into an idealized two-dimensional free-surface wetland flow (Zeng, L., Chen, G.Q., 2009b. Ecological degradation and hydraulic dispersion of contaminant in wetland. Ecol. Model., doi:10.1016/j.ecolmodel.2009.10.024), an ecological risk assessment model for the typical case of a pulsed contaminant emission into a realistic three-dimensional wetland channel flow is presented in this paper for the fate of cross-sectional mean concentration under environmental dispersion. An environmental dispersion model for the mean concentration is devised as an extension of Taylor’s classical analysis on dispersion in fluid flows. The velocity distribution and the environmental dispersivity in the fully developed steady flow through the wetland is found and illustrated with limiting cases covering various known solutions for the porous media flow between parallel plates, flow in a shallow wetland, sweeping flow in a densely vegetated wetland, and single phase flow in a channel. Obtained by Aris’s method of moments, the environmental dispersivity is shown characterized with multi-scale asymptotic time variations with stem dominated stage, transitional stage, and width-depth-stem dominated stage. Based on the solution for the evolution of contaminant cloud in the wetland channel flow, critical length and duration of the contaminant cloud with concentration beyond given environmental standard level are concretely illustrated for typical pollutant constituents in wastewater emission. Under the same emission intensity and environmental standard, the duration of contaminant cloud in the wetland channel is revealed shorter than that in a free surface wetland, due to the lateral effect.     

Influence of support on catalytic behavior of nickel catalysts in the steam reforming of ethanol for hydrogen production

Al₂O₃, MgO, SiO₂ and ZnO-supported nickel catalysts were prepared and evaluated in the ethanol steam reforming for hydrogen production. It is shown that the catalytic behavior can be influenced depending on the experimental conditions employed and chemical composition of the catalyst.     

Are low infidelity rates in feral horses due to infanticide?

A growing number of studies conducted on diverse taxa have shown that extra-pair/group paternity is higher than what would be predicted from behavioral observations alone. While it may be beneficial for females to mate with multiple males, this often results in offspring not sired by the behavioral father, which could influence offspring survival, especially in social mammals. Feral horses (Equus caballus) maintain stable social relationships over several years, usually with one stallion defending a harem band of unrelated mares against other males. Sneak copulations by subordinate males have been observed and mares sometimes change bands, both of which can result in foals sired by males other than the dominant band stallion. We measured female fidelity in free-ranging feral horses in 23 bands, with 51 foals over four foaling seasons and tested offspring paternity against parental behaviors. We used 12 polymorphic microsatellite loci and the program CERVUS 2.0 to determine and exclude potential sires. The majority of mares remained in the band with the sire of their foal resulting in most foals being sired by the band stallion. Most foals that were not sired by the band stallion were born in the year after a round-up and we could not determine if they were the result of band changing or sneak copulations. Foals born into a band without their sire had lower survival rates and mothers were significantly more protective of foals not sired by the band stallion. These findings suggest that band stability increases the reproductive success of mares and support the importance of infanticide risk in equid social structure.     

Investigation and modeling of solar UV-induced chlorine decay in disinfection contact basins at full-scale wastewater treatment plants

Residual chlorine loss due to UV sunlight in the chlorine disinfection contact basins (DCBs) was investigated at two full-scale wastewater treatment plants (WWTPs). Chlorine decay due to solar UV-induced photochemical reaction was found to be significant and had diurnal and seasonal variations. The total chlorine loss due to sunlight ranged from 19 to 26% of the total chlorine chemical use at the two plants studied. Covering chlorine contact basins led to more stable chlorine demand regardless of the diurnal and seasonal sunlight intensity. Therefore, covering chlorine contact basins offers more stable, or accurate, chlorine dosage and effluent residual control and requires less effort by plant operators. A mathematical model was developed to calculate the amount of UV-induced chlorine decay. The model developed can be used to estimate the UV-induced chlorine decay rate and total chlorine loss due to sunlight at WWTPs with various basin configurations, flowrates, chlorine dosages, and geographical locations. The model results allow the capital cost of covering needs to be assessed against the chlorine chemical cost savings.     

Uncertainty Analysis In Dissolved Oxygen Modeling in Streams

Uncertainty analysis in surface water quality modeling is an important issue. This paper presents a method based on the first-order reliability method (FORM) to assess the exceedance probability of a target dissolved oxygen concentration in a stream, using a Streeter–Phelps prototype model. Basic uncertainty in the input parameters is considered by representing them as random variables with prescribed probability distributions. Results obtained from FORM analysis compared well with those of the Monte Carlo simulation method. The analysis also presents the stochastic sensitivity of the probabilistic outcome in the form of uncertainty importance factors, and shows how they change with changing simulation time. Furthermore, a parametric sensitivity analysis was conducted to show the effect of selection of different probability distribution functions for the three most important parameters on the design point, exceedance probability, and importance factors. Note: This version was published online in June 2005 with the cover date of August 2004.     

Stable sulfur isotope ratio indicates long-term changes in sulfur deposition in the Broadbalk experiment since 1845

Archived wheat (Triticum aestivum L.) grain and straw, and soil samples from the control plot of the Rothamsted Broadbalk Experiment, located in southeastern England and established in 1843, were used to investigate the effects of dramatically changing SO2 pollution inputs on the concentrations and stable isotope ratios (delta34S) of S in the samples. Representative coal samples from UK major coal fields were also determined for delta34S. Concentrations of S showed no clear trends in either grain or straw over the 155 years from 1845 to 1999. However, grain and straw delta34S decreased rapidly from 6 to 7/1000 in 1845 to -2 to -5/1000 in the early 1970s, and since then have increased to 0.5 to 2/1000 in the late 1990s. This pattern mirrored the trend of UK SO2 emissions over the 155 years. Both grain and straw delta34S correlated strongly and negatively with UK SO2 emissions (R2 > 0.89), but the relationships were different for the pre- and post-1970 data sets. Soil delta34S also decreased considerably, from 8.2/1000 in 1865 to 3.7 to 4.5/1000 during 1965-1999. A negative delta34S value was inferred for the anthropogenic S deposited at the experimental site before 1970, and further confirmed by negative delta34S values (-6 to -10/1000) found in the coal samples from southeastern England and southern Wales. Based on the S isotope ratios, we estimated that anthropogenic S contributed 62 to 78% of the S uptake by wheat at the peak of SO2 emissions, and accounted for 28 to 37% of the topsoil S in 1965.