Vapour intrusion from the vadose zone—seven algorithms compared

Background, aim and scope  

Vapours of volatile organic compounds (VOCs) emanating from contaminated soils may move through the unsaturated zone to the subsurface. VOC in the subsurface can be transported to the indoor air by convective air movement through openings in the foundation and basement. Once they have entered the building, they may cause adverse human health effects. Screening-level algorithms have been developed, which predict indoor air concentrations as a result of soil (vadose zone) contamination. The present study evaluates seven currently used screening-level algorithms, predicting vapour intrusion into buildings as a result of vadose zone contamination, regarding the accuracy of their predictions and their usefulness for screening purpose. Screening aims at identifying contaminated soils that should be further investigated as to the need of remediation and/or the presence of an intolerable human health risk. To be useful in this respect, screening-level algorithms should be sufficiently conservative so that they produce very few false-negative predictions but they should not be overly conservative because they might have insufficient discriminatory power.     

Spatial structure and inter-firm networks of technical and information producer services in Seoul,Korea

A spatial and sectoral reorganisation of producer services has begun to change the urban structure of Seoul. In addition to the existing centre of the CBD, two areas, Kangnam and Yongdeungpo, have emerged as the new centres of producer services in Seoul resulting from relocations from the CBD and the location of firm start-ups and spin-offs, so creating a multi-centred structure. There is a difference between the centres related to the fact that Kangnam is specialised in advanced services and has strong local networks among service firms, firms in Yongdeungpo have strong forward linkages to nearby manufacturing firms and to larger producer service firms, while firms in the CBD are relatively older and have much more intensive overseas ties. This outcome illustrates that shifts in the organisation of producer services in favour of outsourcing have been felt in shifts in spatial patterns. These new structures illustrate that producer service location and operation have a powerful influence upon the pattern of development in Seoul.     

Release of critically endangered crocodiles: Development and application of a food web approach to determine suitability of release habitat

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