Ppm Total Hydrocarbons Research Articles

Determination of kinetic parameters of rice husks in oxygen using thermogravimetric analysis

Rice husks, as a renewable source of energy, can provide a continuous supply of liquid and gaseous fuels through thermochemical conversion processes. However, a proper understanding of the thermal properties and reaction kinetics of rice husk plays an important role in the efficient design, operation and modeling of these systems. This paper describes the kinetics of the thermal degradation of four varieties of rice husk (Lemont LG, ROK 14, CP 4 and Pa Potho) in pure oxygen (99.5% oxygen, 50 ppm water, 40 ppm total hydrocarbons and 1 ppm solvents) atmosphere from ambient temperature to 700°C at the heating rate of 20°C min −1. Two distinct reaction zones were observed for all varieties of rice husk. The kinetic parameters (activation energy, pre-exponential factor and order of reaction) were determined for the two reaction zones by applying thermo-analytical techniques to the reaction kinetics. Thermal degradation rates in the first reaction zone were significantly higher than those in the second reaction zone. The activation energies were in the range of 142.7–188.5 kJ mol −1 and 11.0–16.6 kJ mol −1 for the first and second reaction zones, respectively.

Brittlestars, Biomarkers and Beryl: Assessing the Toxicity of Oil-Based Drill Cuttings Using Laboratory, Mesocosm and Field Studies

Effects of drill cuttings on burrowing brittlestars (Amphiura chiajei and A. filiformls) were compared at different levels of response, from acute laboratory experiments to chronic field studies. Acute toxicity tests showed that drill cuttings containing oil-based muds had a very low toxicity (LC50 52,800 ppm total hydrocarbons in test sediment) but sub-lethal effects were detected at much lower levels using a variety of biomarkers and assays. Chronic sub-lethal effects were detected around the Beryl oil platform in the North Sea where the levels of oil in the sediment were very low (<3 ppm total hydrocarbons in sediment) and brittlestars were excluded from areas nearer the platform with higher sediment oil content. These results suggest that acute toxicity tests are a poor predictor of chronic response in these animals. the relationship between toxicity at different levels of response and the predictive power of laboratory studies is discussed.

Crossflow microfiltration of oily water

Two α-alumina ceramic membranes (0.2 and 0.8 μm pore sizes) and a surface-modified polyacrylonitrile membrane (0.1 μm pore size) were tested with an oily water, containing various concentrations (250–1000 ppm) of heavy crude oil droplets of 1–10 μm diameter. Significant fouling and flux decline were observed. Typical final flux values (at the end of experiments with 2 h of filtration) for membranes at 250 ppm oil in the feed are ≈30–40 kg m −2 h −1. Increased oil concentrations in the feed decreased the final flux, whereas the crossflow rate, transmembrane pressure, and temperature appeared to have relatively little effect on the final flux. In all cases, the permeate was of very high quality, containing <6 ppm total hydrocarbons. The addition of suspended solids increased the final membrane flux by one order of magnitude. It is thought that the suspended solids adsorb the oil, break up the oil layer, and act as a dynamic or secondary membrane which reduces fouling of the underlying primary membrane. Resistance models were used to characterize the type of fouling that occurs. Both the 0.2 μm and the 0.8 μm ceramic membranes appeared to exhibit internal fouling followed by external fouling, whereas external fouling characterized the behavior of the 0.1 μm polymer membrane from the beginning of filtration. Examination of the external fouling layer showed a very thin hydrophobic oil layer adsorbed to the membrane surface. This oil layer made the membrane surface hydrophobic, as demonstrated by increased water-contact angles. The oil layer proved resistant to removal by hydrodynamic (shear) methods. By extracting the oil layer with tetrachloroethylene, followed by IR analysis, its average thickness at the end of a 2 h experiment under typical conditions was determined to be 60 μm for the 0.2 μm ceramic membrane and 30 μm for the 0.1 μm polymer membrane. These measured amounts of oil associated with the membrane at the end of the experiments are in good agreement with those determined from a simple mass balance, in which it is assumed that all of the oil associated with the permeate collected is retained on or in the membrane, indicating that the tangential flow did not sweep the rejected oil layer to the filter exit.

Effects of Incubation in Oiled Sediment on Emergence of Capelin (Mallotus villosus) Larvae

Capelin (Mallotus villosus) were incubated in oiled sediment (range of initial concentrations 0–400 ppm total hydrocarbons) from the blastula stage to emergence of larvae. Concentrations of individual and total hydrocarbons in the sediment and interstitial water declined by ≈80–90% over the 28-d exposure period. Larvae from oiled sediment emerged ≈0.5–1 d earlier than did control larvae, and the percentage of larvae emerging was greater in the oiled treatments. Yolk length of exposed larvae after emergence was 10% greater than that of controls; head length (a measure of body size) was 1% less. The emergence behaviour of exposed larvae serves as an adaptive response to stress which enables more larvae to leave the contaminated sediment quickly. The yolk and body size effects would probably not affect survival. Therefore, oiled sediment in the tested range would not significantly affect embryos and larvae prior to emergence. Delayed effects on emerged larvae, which are more sensitive than embryos, may be more important.

THE ROLE OF JUNCUS ROEMERIANUS IN CLEANUP OF OIL-POLLUTED SEDIMENTS

ABSTRACT Several locations in the Mississippi Sound of the Central Gulf of Mexico have been sites of accidental and simulated oil spills over the past decade, providing excellent testing grounds for detecting interactions of indigenous marsh vegetation with petroleum pollutants. Spartina alterniflora and Juncus roemerianus, dominant marsh plants of this region, show resilience in the face of acute oil spills, with J. roemerianus decidedly more resilient in chronic exposures. More important, J. roemerianus can remove large amounts of petroleum hydrocarbons from the underlying sediments and from the water column. Collections of Juncus and underlying sediment from five estuarine environments showed levels and distributions of petroleum hydrocarbons in the aerial leaf portions that mirrored those found in the sediment substrate. Up to 9,000 ppm total hydrocarbons were found in J. roemerianus growing in oil-contaminated sediments. In two different studies, salt marsh plots of Juncus roemerianus and Spartina alterniflora were exposed to sediments inoculated with three different crude oils, an alkene, chrysene, and naphthalene, and uptake was monitored with time. Juncus was able to take up hydrocarbons unaltered within 10 days. Spartina showed no evidence of uptake, though it did show relative increases in lipid fractions.

The effects of a water-soluble petroleum fraction on the neuroid electrical activity of the hydroid coelenterate Tubularia crocea

Several properties of the excitable epithelium of the hydroid coelenterate, Tubularia crocea, are affected by a water-soluble fraction (WSF) of Platform Holly, Monterey Formation, crude oil (100% WSF= 20 ppm total hydrocarbons). In a flowing seawater system, 0·5 ml pulses of 1 WSF cause a significant increase in the epithelial pulse activity, while a 10·min exposure to 0·1% WSF produces a significant increase in the epithelial pulse frequency. Electrophysiological responses to the volatile and non-volatile subfractions are equal, but significantly lower than those to the whole WSF. Behaviorally, the 100% WSF elicits a more vigorous proximal tentacle closure than either its volatile or non-volatile subfraction. However, the closure response to the volatile subfraction exceeds that for the non-volatile component. Of the two epithelial neuroid pulse systems, the hydranth pulse (HP) system is affected to a greater extent than the neck pulse (NP) system. During 10 minutes' treatment with 100% WSF the amplitude of the neck pulses and hydranth pulses declined by 50% and 80%, respectively. The maximum 3H-toluene uptake from 100% WSF also occurs within this period, and sodium and calcium concentrations fluctuate rapidly. These results suggest that a rapid bioaccumulation of hydrocarbons by T. crocea alters membrane permeability, upsetting critical ion gradients which, in turn, alter the firing frequency of the epithelial conducting systems. This study demonstrates that concentrations of WSF approaching environmentally realistic levels (in areas of chronic pollution) alter the epithelial conducting systems that co-ordinate important elements of behavior in Tubularia. This system provides a sensitive neuroid-behavioral assay for aquatic contaminants.

COMPARATIVE UPTAKE OF NAPHTHALENES FROM WATER AND OILED SEDIMENT BY BENTHIC AMPHIPODS1

ABSTRACT The benthic amphipod, Anonyx laticoxae, was exposed to whole oil on sediments or water extracts of Prudhoe Bay crude oil under both static and flowing conditions. Time periods of exposure ranged from 4 to 27 days and, while a range of compounds was present, the only class measured in water, tissues, and sediments was naphthalenes. Compared to levels in the surrounding environment (sediment or water) tissue magnification was least during sediment exposures (2–4 times), greatest in a flowing exposure system (∼1000 times), and intermediate during static water exposure (10–50 times). During a constant exposure to 22 ppb total naphthalenes (0.506 ppm total hydrocarbons) the amphipods reached a threshold of accumulation after about seven days, and the majority of contamination was from alkylnaphthalenes. Sediment exposures demonstrated relatively low bioavailability of naphthalenes and the route of entry appeared to be via interstitial and water column contamination. It appears that release of naphthalenes from both oiled sediments and tissues is largely controlled by water solubilities of the components, but metabolic processes may supplement this activity.

The Amoco Cadiz oil spill—Lines of study and early observations

The French Ministry of Environment is sponsoring a long-term program to assess the ecological impact of the Amoco Cadiz oil spill on the marine environment. Nine French organizations, along with U.S. and Canadian agencies, are participating in a 3-yr program to monitor the chemical quality of the water, sediments, and marine organisms, study ecological effects and microbiological processes, and conduct toxicological research. Collective reports document the oil impact as follows: the fresh crude oil was rapidly dispersed by rough seas in the first fortnight, killing numerous marine organisms; the general spreading of the oil was controlled with all rocky and sandy shores facing the west progressively oiled; winds turned easterly; spring sand aeration in the upper part of the beaches with high tidal coefficient buried the heavy oil deposits to depths of 50-80 cm; low energy areas, Abers, Bay of Morlaix, and Lannion, were heavily polluted and will likely be polluted for long periods of time; and the resultant hydrocarbon levels in subtidal sediment in the Bay of Lannion and the Bay of Morlaix were 1%-2% at 8-30 m depth. Birds were directly affected with 4,000 dead birds collected. Algae seem to be in good physiological condition. The zooplankton were almost absent 1 mo after the spill, but were beginning to reappear the following month. The commercial fishing activity in the area was interrupted for only 1 mo. The oyster beds were highly polluted with 150-400 ppm total hydrocarbons and could not be used for several months.

A long-term study of the effects of water-soluble fractions of No. 2 fuel oil on the survival, development rate, and growth of the mud crab Rhithropanopeus harrisii

Mud crabs, Rhithropanopeus harrisii (Gould), were exposed continuously for 6 months after hatching to water-soluble fractions (WSF) of No. 2 fuel oil. Survival, growth and development rate were monitored during this time. The zoeal stages were the most sensitive to fuel oil. A 20% WSF (0.36 ppm total naphthalenes, 1.26 ppm total hydrocarbons) was acutely toxic to these stages. Of the zoeal stages, the first stage appeared to be the most sensitive. The combined duration of the 4 zoeal stages was significantly increased by increasing WSF exposure concentrations. The megalopa and crab stages were not particularly sensitive to continued petroleum hydrocarbon exposure, particularly when compared to zoeal stages. However, mean duration of the megalopa and first crab stages was significantly affected by oil exposure. Individuals which survived the highest exposure concentrations as larvae appeared to grow larger during the crab stages, so that at the end of 6 months comparably staged crabs were equal to or larger than both control crabs and those exposed to low WSF concentrations. Stage distributions at the end of 6 months showed no differences due to WSF exposure. Sex ratios, which could be determined at the end of 6 months, were approximately 1, indicating no sex-related differential sensitivity to WSF exposure, at least as larvae or juveniles. The data indicate that these crabs possess considerable ability to recover from the effects of chronic sublethal exposure to petroleum hydrocarbons. The most deleterious effects of oil pollution on this species may be due to its impact on larval recruitment into the adult population.

Studies on the analysis of hydrocarbons from incinerator effuents with a combustible gas indicator.

Abstract A combustible gas indicator with a 10 to 1 sensitivity scale has been found to be applicable to the measurements of C2 and higher hydrocarbons from incinerator effluents. Samples are collected in evacuated stainless steel 34-liter tanks. Response to carbon monoxide and methane was differentiated from higher hydrocarbons through the difference in indication with and without a tube of activated carbon in the sampling train. The method is applicable to differentiate between incinerators emitting less than 50 ppm total hydrocarbons and those emitting higher concentrations.