Desalination impacts on the coastal environment: Ash Shuqayq, Saudi Arabia.

Ash Shuqayq (Saudi Red Sea coast) is approximately 28km long and characterised by narrow rocky headlands with intermittent pocket beaches. Fifty-two sediment samples from six different environments (beach, dune, sabkha, tidal/lagoon, offshore and wadi) were analysed. Testing showed that beach and dune sands are mainly medium to fine grained, with some very coarse sand (MZ=-0.59ø). Both beach and dune sands are moderately well to moderately sorted, although some are poorly sorted due to an influx of wadi sediments. Sediment source together with littoral reworking contributed to grain size variation. Carbonate content varied between 1.5% and 23%, whilst the organic content varied between 1.1% and 13%. Spatial analysis showed increasing southward carbonate and organic content, with both correlated (r=0.57). Sabkha sediments had significantly higher carbonate percentages (t=2.898; df=18; p<0.01) and results suggested origins are similar for both UAE Arabian Sea and Saudi Arabian Red Sea coasts. X-ray diffractions show beach and dune sediments are mainly composed of detrital quartz and plagioclase feldspar with uncommon amounts of chlorites. Analysis of sediment characteristics, composition and shoreline distribution alongside coastal processes, indicate that high chlorite levels are probably caused by desalination processes. Due to human and ecosystem health consequences and the likely increased demand for desalination plants, similar analyses should be undertaken elsewhere, e.g. the Mediterranean.

Methods for successful follow-up of elusive urban populations: an ethnographic approach with homeless men.

Public health is paying increasing attention to elusive urban populations such as the homeless, street drug users, and illegal immigrants. Yet, valid data on the health of these populations remain scarce; longitudinal research, in particular, has been hampered by poor follow-up rates. This paper reports on the follow-up methods used in two randomized clinical trials among one such population, namely, homeless men with mental illness. Each of the two trials achieved virtually complete follow-up over 18 months. The authors describe the ethnographic approach to follow-up used in these trials and elaborate its application to four components of the follow-up: training interviewers, tracking participants, administering the research office, and conducting assessments. The ethnographic follow-up method is adaptable to other studies and other settings, and may provide a replicable model for achieving high follow-up rates in urban epidemiologic studies.