Water quality assessment of Ogun river, South West Nigeria.

The quality of Ogun river in South-West, Nigeria was studied by a field survey for a period of 1 year (covering dry season and rainy season). Water samples were collected from thirteen sites and analysed for physico-chemical and bacteriological parameters as well as heavy metals using standard methods. Generally, the values obtained for turbidity, phosphate, oil and grease, iron and faecal coliform from all the sites in both seasons were above the maximum acceptable limit set by the World Health Organization (WHO) for drinking water. Also, the manganese content from all the sites in the dry season, lead concentrations from three sites in the dry season and cadmium concentrations from some sites in both seasons were above the WHO limit. The values obtained for total dissolved solids, dissolved oxygen and chloride at site M in the dry season and nitrate at site J in the rainy season were also above the WHO limit. Pollution of Ogun river water along its course is evidenced by the high concentrations of pollution indicators, nutrients and trace metals above the acceptable limit. This poses a health risk to several rural communities who rely on the river primarily as their source of domestic water. The study showed a need for continuous pollution monitoring programme of surface waters in Nigeria.

Cadmium, copper and nickel levels in vegetables from industrial and residential areas of Lagos City, Nigeria.

The levels of cadmium, copper and nickel in five different edible vegetables, Talinum triangulare, Celosia trigyna, Corchorus olitorus, Venomia amygydalina and Telfaria accidentalis, and the soils in which they were grown, from three industrial and three residential areas of Lagos City, Nigeria, were determined using atomic absorption spectrophotometry. The results obtained for these three heavy metals from the industrial areas were higher than those of the residential areas as a result of pollution. Industrial area results for vegetables ranged between 1.13 and 1.67 microg/g for cadmium; 25.08 and 56.84 microg/g for copper and 1.33 and 2.06 microg/g for nickel. There were statistically significant differences (P<0.05) between the levels of copper and nickel in all the vegetables studied from industrial and residential areas, while there was no statistically significant difference for cadmium. The results also show that Corchorus olitorus (bush okra) has the ability to accumulate more copper and nickel than the other vegetable studied but has the least ability to accumulate cadmium.

Pb, Zn, and Cu levels in tree barks as indicator of atmospheric pollution.

Barks of seven species of trees were sampled at 32 locations having different pollution levels in Abeokuta, Nigeria. The concentrations of Pb, Zn, and Cu were determined by atomic absorption spectrometry. The Pb and Zn contents, 1.9-159.8 and 16.5-659.1 micrograms g-1, dry weight respectively, correlate with traffic volume, indicating pollution from anthropogenic sources. The results obtained for Cu, 4.2-20.7 micrograms g-1, dry weight, though lower, were still significant but did not show any correlation with traffic density. The study also confirms the suitability of Azadirachta indica (Dogoyaro--a very popular local tree) as a suitable bio-indicator of aerial fallout of heavy metals.

The effects of race and social class on clinical judgment.

Asked 61 male clinical psychologists (21 blacks and 40 whites) to assess case histories that were presented to them to determine whether racial or social class biases could be detected. In order to avoid the apparent artificial results or weak interpretations of past research, only cases with concurrently validated diagnoses and 4-year follow-up were used. An equal number of positive and negative clinical outcomes were included. Diagnosis, disposition, and rated severity were studied. The following results were found: (1) diagnosis for all psychologists was guided by case characteristics, not bias; (2) severity was related strongly to diagnosis; (3) disposition followed judgments of severity and diagnosis, not bias. The question was raised whether clinical investigators may not have overdramatized bias in psychodiagnosis and clinical judgment.