Selection of adsorbents for treatment of leachate: batch studies of simultaneous adsorption of heavy metals

The simultaneous adsorption of copper (Cu), cadmium (Cd), nickel (Ni), and lead (Pb) ions from spiked deionized water and spiked leachate onto natural materials (peat A and B), by-product or waste materials (carbon-containing ash, paper pellets, pine bark, and semi-coke), and synthetic materials (based on urea-formaldehyde resins, called blue and red adsorbents) or mixtures thereof was investigated. The adsorbents that gave the highest metal removal efficiencies were peat A, a mixture of peat B and carbon-containing ash, and a mixture of peat A and blue. At an initial concentration of 5 mg/l for each metal, the removal of each species of metal ion from spiked water and spiked leachate solutions was very good (>90%) and good (>75%), respectively. When the initial concentration of each metal in the solutions was twenty times higher (100 mg/l), there was a noticeable decrease in the removal efficiency of Cu²⁺, Cd²⁺, and Ni²⁺, but not of Pb²⁺. Langmuir monolayer adsorption capacities, q_m, on peat A were found to be 0.57, 0.37, and 0.36 mmol/g for Pb²⁺, Cd²⁺, and Ni²⁺, respectively. The order of metal adsorption capacity on peat A was the same in the case of competitive multimetal adsorption conditions as it was for single-element adsorption, namely Pb²⁺ > Cd²⁺ ≥ Ni²⁺. The results show that peat alone (an inexpensive adsorbent) is a good adsorbent for heavy metal ions.     

The impact of livestock-farming on welsh streams: the development and testing of a rapid biological method for use in the assessment and control of organic pollution from farms

Organic wastes from intensive agriculture are a major cause of surface-water pollution in Great Britain. There are a large number of possible sources for such pollution, and there is a need to target the efforts of pollution-control authorities to the worst-affected parts of catchments. This paper describes the development of a rapid method for the identification of polluted streams based upon the macro-invertebrate fauna. An indicator key was developed by TWINSPAN classification of data from benthic sampling at 55 sites in West Wales. The key requires assessment of the abundance of four macroinvertebrate taxa and of the extent of 'sewage-fungus' growth, all of which can be determined by examination in the field. The key can separate sites into three groups representing different levels of pollution impact as indicated by differences in biotic indices and chemical data. The system was tested successfully at a further 146 sites in West Wales resulting in the notification of 49 farms to the pollution-control authorities. Non-biologists were able to use the key efficiently after a short period of training. A further test involving 51 sites in Devon indicated that the technique may be adaptable to other parts of Great Britain. It is envisaged that indicator systems designed to suit local fauna may have a major role in a pro-active strategy developed to combat pollution from farms because they have potential advantages over more complex biological methods currently in use.     

Prenatal diagnosis of monosomy 18 and ring chromosome 18 mosaicism

The case of monosomy 18/ring chromosome 18 mosaicism which was detected prenatally by amniocentesis is presented. The pregnancy was terminated in week 18. Autopsy showed complex malformation of the fetus consisting of cebocephaly, hypotelorism, microphthalmia, severe defects of brain development, and arrest of placental maturation.