Organic Liquids Storage Tanks Volatile Organic Compounds (VOCS) Emissions Dispersion and Risk Assessment in Developing Countries: The Case of Dar-Es-Salaam City, Tanzania

The emission estimation of nine volatile organic compounds (VOCs) from eight organic liquids storage tanks companies in Dar-es-Salaam City Tanzania has been done by using US EPA standard regulatory storage tanks emission model (TANKS 4.9b). Total VOCs atmospheric emission has been established to be 853.20 metric tones/yr. It has been established further that petrol storage tanks contribute about 87% of total VOCs emitted, while tanks for other refined products and crude oil were emitting 10% and 3% of VOCs respectively. Of the eight sources (companies), the highest emission value from a single source was 233,222.94 kg/yr and the lowest single source emission value was 6881.87 kg/yr. The total VOCs emissions estimated for each of the eight sources were found to be higher than the standard level of 40,000 kg/yr per source for minor source according to US EPA except for two sources, which were emitting VOCs below the standard level. The annual emissions per single source for each of the VOCs were found to be below the US EPA emissions standard which is 2,000~kg/yr in all companies except the emission of hexane from company F1 which was slightly higher than the standard. The type of tanks used seems to significantly influence the emission rate. Vertical fixed roof tanks (VFRT) emit a lot more than externally floating roof tanks (EFRT) and internally floating roof tanks (IFRT). The use of IFRT and EFRT should be encouraged especially for storage of petrol which had highest atmospheric emission contribution. Model predicted atmospheric emissions are less than annual losses measured by companies in all the eight sources. It is possible that there are other routes for losses beside atmospheric emissions. It is therefore important that waste reduction efforts in these companies are directed not only to reducing atmospheric emissions, but also prevention of the spillage and leakage of stored liquid and curbing of the frequently reported illegal siphoning of stored products. Emission rates for benzene, toluene, and xylene were used as input to CALPUFF air dispersion model for the calculation of spatial downwind concentrations from area sources. By using global positioning system (GPS) and geographical information system (GIS) the spatial benzene concentration contributed by organic liquid storage tanks has been mapped for Dar-es-Salaam City. Highest concentrations for all the three toxic pollutants were observed at Kigamboni area, possibly because the area is located at the wind prevailing direction from the locations of the storage tanks. The model predicted concentrations downwind from the sources were below tolerable concentrations by WHO and US-OSHA. The highest 24 hrs averaging time benzene concentration was used for risk assessment in order to determine maximum carcinogenic risk amongst the population exposed at downwind. Established risk for adult and children at 2.9×10^-3 and 1.9×10^-3 respectively, are higher than the acceptable US-EPA risk of 1×10^-6. It is very likely that the actual VOCs concentrations in some urban areas in Tanzania including Dar-es-Salaam City are much higher than the levels reported in this study when other sources such as petrol stations and motor vehicles on the roads are considered. Tanzania Government therefore need to put in place: an air quality policy and legislation, establish air quality guidelines and acquire facilities which will enable the implementation of air quality monitoring and management programmes.     

Background level of risk determines the intensity of predator neophobia in juvenile convict cichlids

Behavioural ecology is rife with examples of prey animals that are able to adjust the intensity of their anti-predator response to match background risk levels. Often, preys need experience with predators before they will invest in costly anti-predator responses. This means that prey animals often fail to respond to predators during their first encounter. Recently, we have shown that prey raised under high-risk conditions may exhibit avoidance of potential predation cues independent of experience (neophobia). Such phenotypically plastic neophobic predator responses may reduce the initial costs of learning ecologically relevant threats while maintaining sufficient behavioural plasticity to respond to variation in local conditions. Here, we test if induced neophobia results in threat-sensitive behavioural trade-offs in response to a novel chemosensory cue. Our first experiment shows that while juvenile convict cichlids (Amatitlania nigrofasciata) pre-exposed to high (but not low) risk conditions exhibited predator avoidance to a novel odour (rainbow trout, Oncorhynchus mykiss), the response intensity was not influenced by the concentration of trout odour detected. Our second experiment demonstrated that the intensity of anti-predator response towards a novel predator cue was dependent upon the level of background risk. Convict cichlids pre-exposed to high-risk conditions showed stronger responses than those pre-exposed to low-risk conditions, while cichlids pre-exposed to intermediate-risk conditions exhibited intermediate response intensities. Together, these data demonstrate that background levels of risk and not the concentration of novel cues detected shape the induced neophobic response pattern of juvenile convict cichlids.     

Three different origins for apparent triploid/diploid mosaics

Four apparent triploid/diploid mosaic cases were studied. Three of the cases were detected at prenatal diagnosis and the other was of an intellectually handicapped, dysmorphic boy. Karyotypes were performed in multiple tissues if possible, and the inheritance of microsatellites was studied with DNA from fetal tissues and parental blood. Non-mosaic triploids have a different origin from these mosaics with simple digyny or diandry documented in many cases. Three different mechanisms of origin for these apparent mosaics were detected: (1) chimaerism with karyotypes from two separate zygotes developing into a single individual, (2) delayed digyny, by incorporation of a pronucleus from a second polar body into one embryonic blastomere, and (3) delayed dispermy, similarly, by incorporation of a second sperm pronucleus into one embryonic blastomere. In three of the four cases, there was segregation within the embryos of triploid and diploid cell lines into different tissues from which DNA could be isolated. In case 2 originating by digyny, the same sperm allele at each locus could be detected in both triploid and diploid tissues, which is supportive evidence for the involvement of a single sperm and for true mosaicism rather than chimaerism. Similarly, in case 4 originating by dispermy, the same single ovum allele at each locus could be detected in diploid and triploid tissues, confirming mosaicism. In the chimaeric case (case 3), the diploid line had the karyotype 47,XY,+16 while the triploid line was 69,XXY. This suggests a chimaera, since, in a true mosaic, the triploid line should also contain the additional chromosome 16. Supporting the interpretation of a chimaeric origin for this case, the DNA data showed that the triploidy was consistent with MII non-disjunction (i.e. involving a diploid ovum). In the mosaic cases (1, 2, 4), there was no evidence of the involvement of a diploid sperm or a diploid ova, and in triploid/diploid mosaicism, an origin from a diploid gamete is excluded, since all such conceptuses would be simple triploids. In one of these triploid/diploid mosaics detected at prenatal diagnosis by CVS, the triploid line seemed to be sequestered into the extra-fetal tissues (confined placental mosaicism). This fetus developed normally and a normal infant was born with no evidence of triploidy in newborn blood or cord blood at three months of age. Copyright © 2003 John Wiley & Sons, Ltd.     

Mobility of Polychlorinated Aromatic Compounds in Soils Contaminated With Wood-preserving Oil

Greater understanding of the mobility of polychlorinated aromatic compounds in soils is needed to investigate contamination and design suitable remediation strategies for sites contaminated with wood-preserving oil. The objectives of this study were (1) to develop a suitable aqueous batch extraction method for soil containing wood-preservative residues; (2) to determine partition coefficients for the primary contaminants [pentachlorophenol (PCP), polychlorinated dibenzo-p-dloxins (PCDDs), and polychlorinated dibenzofurans (PCDFS)] in oil, soil, and aqueous phases; and (3) to evaluate the potential soil migration of the primary contaminants. In a three-phase oil-soil-water mixture, PCP, PCDDs, and PCDFs were partitioned to the greatest extent in the oil phase. These results suggest that the migration of contaminants can occur in a saturated subsurface soil zone containing an oil phase at a wood-preserving site. In the absence of a free oil phase, PCDDs and PCDFs were highly partitioned onto soil and were considered non-leachable in the aqueous phase. However, PCP was considered highly teachable from contaminated soil containing only an aqueous liquid phase. Results from this study Indicate that removal of any free oil phase present in subsurface soil should have highest priority during the cleanup of contaminated wood-preserving sites.     

Comparison of Laboratory Batch Methods and Large Columns for Evaluating Leachate from Monofilled Solid Wastes

Analyte concentrations in aqueous leachates from polyethylene tanks filled with five different solid wastes were compared with those in extracts from five laboratory batch procedures. Solid wastes used in the study included: electroplating sludge, electric arc furnace dust, paint Incinerator ash, mine tailings, and municipal refuse incinerator ash. Batch extraction procedures used to extract the solid wastes Included: Monofilled Waste Extraction Procedure (MWEP), U.S. EPA Extraction Procedure (EP), Ham Procedure C (HAM-C), Acetate Buffer Extraction Procedure (ABEP), and Saturated Paste Procedure (PASTE).

Analyte concentrations in leachate from the large columns were reproducible and characteristic of each solid waste. In most Instances, analytes in column leachate reached a peak concentration at a liquld-to-solid ratio of 1:1 followed by a gradual to rapid decrease with continued leaching. Analyte concentrations found in large column leachate were related qualitatively to those found in extracts from the batch procedures which used delonlzed water as the extraction medium (i.e., MWEP, HAM-C, and PASTE). Batch extraction procedures using leaching medium containing acetic acid (I.e., EP) or sodium acetate buffer (i.e., ABEP) generally did not reflect analyte concentrations in leachate from the large columns. These results suggest that batch extraction procedures using acetic acid or acetate buffer are less effective for assessing the teachability of monofilled wastes than extraction methods using deionized water as the extraction fluid.     

Hunger-driven response by a nectar-eating jumping spider to specific phytochemicals

The jumping spider Evarcha culicivora (Salticidae) has unusual links to Lantana camara, a plant species to which it is attracted. Three phytochemicals from the headspace of L. camara (1,8 cineole and especially β-caryophyllene and α-humulene) attract adult E. culicivora. These spiders, especially early-instar juveniles, feed on nectar, but adults may use L. camara as mating sites. The hypothesis we consider here is that, for E. culicivora juveniles, although not for adults, responding to plant odor is relevant in the specific context of acquiring nectar meals. We show that juveniles resemble adults by responding to β-caryophyllene and α-humulene, but we found no significant attraction of juveniles to 1,8 cineole. We also show that, compared to sated E. culicivora juveniles, juveniles subjected to a 5-day pre-trial fast responded more strongly to living L. camara plants and to β-caryophyllene and α-humulene, but we found no significant effect of hunger level on response by adults to living plants. These results suggest that attraction to L. camara may have different functions for E. culicivora depending on the stage of its life history.     

After-effects of job-related stress: Families as victims

In recent years, the unique stress experienced by those who do ‘people work’ has been acknowledged by the helping professions as a widespread problem and has been recognized by social scientists as a topic requiring systematic research. This paper begins by briefly reviewing research on the type of job stress experienced by workers in the helping professions. Then, a study of 142 police couples is reported, illustrating the effects of job stress on family life. In a survey study, police officers and their wives described family interactions. Officers who were experiencing stress, as measured by the Maslach Burnout Inventory, were more likely to display anger, spend time off away from the family, be uninvolved in family matters, and to have unsatisfactory marriages. An examination of the coping patterns used to deal with the stress of police work highlights differences between coping strategies used by husbands versus wives.