Risk-based optimization of the design of on-shore pipeline shutdown systems

Crude oil and other liquid materials are transported in large quantities through pipelines. Pipelines are an efficient and safe transport way as compared to both rail and road transportation, both from the economical and environmental points of view. Nevertheless, loss of containment accidents can occur due to external action –a mechanical impact, for example– or to corrosion, aging, etc. Even though the frequency of such events is certainly very low, the effects and consequences on environment can be very important.The consequences of accidents in pipelines can be efficiently reduced through a suitable design of the whole system. One of the points which must be decided in the design is the installation of blocking valves at appropriate distances, so that emergency shutdowns can interrupt the flow of substance and isolate the section where the loss of containment has taken place. In the case of pipe rupture the amount released is therefore limited to the content between two consecutive valves, usually placed according to heuristic criteria. However, if too many valves are used, the capital cost of equipment increases excessively, and if too few are used, the risk of serious accidents increases.In this paper we consider the possibility of improving the design of such systems by applying risk-based optimization criteria. We propose an optimization methodology to solve this conflict by means of an objective function that analyzes the variations in overall costs, including the cost of the investment (with specific reference to blocking valves) and the cost of accidents. The result is an optimum situation in which costs are kept to a minimum. As an example, we apply the methodology to the transportation of gasoline by pipeline.     

Individual, population and community level effects of subtle anthropogenic contamination in estuarine meiobenthos

The study presented here searched for the level of taxonomic resolution required to detect the effects of low-level chronic pollution on estuarine meiobenthic communities. Meiofauna from two sites, with special attention to harpacticoid copepods, was analysed at different taxonomic levels of aggregation using uni- and multivariate methods. Adaptation processes that could buffer biodiversity disruptions were also considered through the analysis of fitness-related and tolerance traits in the harpacticoid copepod Paronychocamptus nanus. Results showed that uni- and multivariate analyses could be inadequate when assessing subtle anthropogenic contamination. Instead, the assessment of inter-population differences in tolerance to the main source of stress rises as a required procedure if potential effects of this type of contamination are being investigated. Specifically, a 96 h acute toxicity test performed with populations from the affected site appears as a faster and reliable general tool to assess impacts of low-level chronic pollution in estuaries.     

Phytoremediation of phenol using Vicia sativa L. plants and its antioxidative response

Common vetch (Vicia sativa L.) is a legume species with an extensive agricultural use. However, the phytoremediation potentiality of this species has not been sufficiently explored because little is known about its resistance to inorganic and organic pollutants. In the present work, phenol tolerance of common vetch was assayed at different stages of growth. Germination index and germination rate decreased only at high phenol concentrations (250 and 500 mg L(-1)), whereas 30-day-old plants were able to tolerate this pollutant, with high removal efficiencies. The activities of antioxidative enzymes, such as peroxidase (POD) and ascorbate peroxidase, increased significantly with the highest phenol concentration, whereas superoxide dismutase activity, malondialdehyde, and H(2)O(2) levels remained unaltered. Besides, an increase in two basic isoforms of POD was observed in plants treated with phenol. The results suggested that common vetch has an efficient protection mechanism against phenol-induced oxidative damage. Moreover, it could tolerate and remove high phenol concentrations, avoiding serious phytotoxic effects. Thus, V. sativa could be considered an interesting tool in the field of phytoremediation.     

Spectroscopic Raman study of sulphate precipitation sequence in Rio Tinto mining district (SW Spain)

Acidic waters and sulphate-rich precipitates are typical by-products of mining activity such as in Rio Tinto (Huelva, SW Spain). This river drains pyrite mines situated in the Iberian Pyrite Belt which have been in operation since the Bronze Age and probably constitutes the oldest continuously operating mining activity over the world. In the present work, we have used Raman spectroscopy to study a wide range of natural mineral samples collected at Rio Tinto which origin is related to evaporation and mineral transformation processes in a wet and extreme acidic environment. In addition, we simulated the phenomenon of mineral precipitation in controlled conditions by using a simulator developed at the laboratory evaporating natural water collected at Rio Tinto. Also, a series of experiments using the same waters as small droplets have been carried out using micro-Raman technique. The droplets were placed on substrates with different chemical composition and reactivity. The results reveal that the precipitation sequence occurred in Rio Tinto mainly comprises copiapite and coquimbite group minerals followed by several other low hydrated iron sulphates. The experiments carried out on droplets allow estimating with higher accuracy the precipitation sequence.     

Effect of arsenic on tolerance mechanisms of two plant growth-promoting bacteria used as biological inoculants

Bacterial ability to colonize the rhizosphere of plants in arsenic (As) contaminated soils is highly important for symbiotic and free-living plant growth-promoting rhizobacteria (PGPR) used as inoculants, since they can contribute to enhance plant As tolerance and limit metalloid uptake by plants. The aim of this work was to study the effect of As on growth, exopolysaccharide (EPS) production, biofilm formation and motility of two strains used as soybean inoculants, Bradyrhizobium japonicum E109 and Azospirillum brasilense Az39. The metabolism of arsenate (As(V)) and arsenite (As(III)) and their removal and/or possible accumulation were also evaluated. The behavior of both bacteria under As treatment was compared and discussed in relation to their potential for colonizing plant rhizosphere with high content of the metalloid. B. japonicum E109 growth was reduced with As(III) concentration from 10 μM while A. brasilense Az39 showed a reduction of growth with As(III) from 500 μM. EPS and biofilm production increased significantly under 25 μM As(III) for both strains. Moreover, this was more notorious for Azospirillum under 500 μM As(III), where motility was seriously affected. Both bacterial strains showed a similar ability to reduce As(V). However, Azospirillum was able to oxidize more As(III) (around 53%) than Bradyrhizobium (17%). In addition, both strains accumulated As in cell biomass. The behavior of Azospirillum under As treatments suggests that this strain would be able to colonize efficiently As contaminated soils. In this way, inoculation with A. brasilense Az39 would positively contribute to promoting growth of different plant species under As treatment.     

Serving the unserved: informal refuse collection in Mexico.

The incomplete collection of municipal solid waste is a significant problem in the cities of many developing countries. Mexican cities collect less than 75% of the waste generated. The uncollected waste generates pollution and poses risks to human health and the environment. Low-income communities comprise most areas that lack refuse collection. In many of the areas where there is no official collection service, informal collectors provide this service for a fee. This paper analyses informal refuse collection in three Mexican cities, and argues that it can supplement municipal collection, create jobs, benefit the economy and help clean up the urban environment.     

Changes in lipid class and fatty acid contents in the ovary and midgut gland of the female fiddler crab Uca tangeri (Decapoda,Ocypodiadae) during maturation

Changes in biochemical composition, lipid class and fatty acid contents were studied in the ovaries and midgut glands of the fiddler crabs Uca tangeri Eydoux during maturation. Wild females were caught during spring and early summer of 1992 in the Bay of Cádiz (southwest Spain), near the mouth of the San Pedro river. Protein and total lipid contents in the ovaries increased significantly from Stages III to IV, at the expense of total carbohydrate, which showed a large decrease during the same period. In the midgut gland, the protein content did not present any significant variation, whereas total lipids and total carbohydrates presented opposite up and down trends during maturation. In the ovary, total polar lipids increased significantly during the final phase of maturation (Stages III to IV), mainly due to the significant contribution of the phosphatidylcholine and phosphatidylethanolamine fractions. In contrast, total neutral lipids showed an upward trend throughout the whole maturation period, mainly due to significant increases of the triacylglycerol fraction. In the midgut gland, total polar lipids (mainly phosphatidylcholine) and total neutral lipids (mainly triacylglycerol) presented significant decreases from Stages II to III, the phase which preceded major increases in both polar and neutral lipids in the ovaries. Cholesterol content did not vary during maturation in either organ, in the ovary or midgut gland. Major fatty acids in the ovaries [16:0, 16:1 (n-7), 18:1 (n-9), 18:1 (n-7), 18:2 (n-6), 18:3 (n-3), 20:4 (n-6), 20:5 (n-3) and 22:6 (n-3)] did, however, accumulate significantly at later stages of maturation. It is noteworthy that arachidonic acid [20:4 (n-6)] content remained constant during all stages of maturation but decreased significantly in total polar lipids in the later phases of maturation. In contrast, eicosapentaenoic acid [20:5 (n-3)] increased significantly in all lipid fractions in the later stages, and docosahexaenoic acid [22:6 (n-3)] remained constant in the polar lipids and increased during later stages in the triacylglycerol fraction. Major fatty acids in the midgut gland lipids showed significant decreases from Stages II to III, just before the final period of maturation.     

Land Use Change on Coffee Farms in Southern Guatemala and its Environmental Consequences

Changes in commodity prices, such as the fall in coffee prices from 2000 to 2004, affect land use decisions on farms, and the environmental services they provide. A survey of 50 farms showed a 35 % loss in the area under coffee between 2000 and 2004 below 700 m with the majority of this area (64 %) being coffee agroforest systems that included native forest species. Loss of coffee only occurred on large and medium-scale farms; there was no change in area on cooperatives. Coffee productivity declined below 1,100 m altitude for sun and Inga shade coffee, but only below 700 m altitude for agroforest coffee. Coffee productivity was 37–53 % lower under agroforests than other systems. Increases in rubber and pasture were related to low altitude large-scale farms, and bananas and timber plantations to mid-altitude farms. Average aboveground carbon stocks for coffee agroforests of 39 t C ha^?1 was similar to rubber plantations, but one-third to one half that of natural forest and timber plantations, respectively. Coffee agroforests had the highest native tree diversity of the productive systems (7–12 species ha^?1) but lower than natural forest (31 species ha^?1). Conversion of coffee agroforest to other land uses always led to a reduction in the quality of habitat for native biodiversity, especially avian, but was concentrated among certain farm types. Sustaining coffee agroforests for biodiversity conservation would require targeted interventions such as direct payments or market incentives specifically for biodiversity.     

Assessment of a Smelter Impact Area Using Surface Soils and Plants

The concentrations of 37 trace elements (Ag, Ba, Be, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Ga, Gd, Ge, La, Li, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sm, Sn, Sr, Tb, Th, Tl, U, V, W, Y, Yb, Zn and Zr) were determined by ICP-MS in surface soils and plants (Sida rhombifolia) sampled around a lead smelter in Lastenia, Province of Tucuman, NW Argentina. Soil and plant patterns of Pb, Cd, Ag, Zn and Cu demonstrate the effects of pollutant dispersion plumes following the prevalent wind directions. The high element concentrations observed, especially Pb (>5,000 mg/kg), could cause serious environmental problems in areas of close proximity to the smelter. Consequently, measures to assess potential consequences for the local population should be considered to determine if measures to protect the environment are necessary.