DOI: 10.1007/s10967-008-7293-5 Journal of Radioanalytical and Nuclear Chemistry, Vol. 279, No.2 (2009) 611–617 0236–5731/USD 20.00 Akadémiai Kiadó, Budapest © 2008 Akadémiai Kiadó, Budapest Springer, Dordrecht Instrumental neutron activation analysis of water hyacinth as a bioindicator along the Nile river, Egypt Ashraf Aly Mohamed, 1 * H. A. Amer, 1 S. Shawky, 2 M. El-Tahawy, 1 A. T. Kandil 3 1 National Centre for Nuclear Safety and Radiation Control, Atomic Energy Authority, 3 Ahmed El-Zomor St., P.O. Box 7551, Nasr City, 11762 Cairo, Egypt 2 International Atomic Energy Agency, Wagramerstr. 5, P.O. Box 100, W-1400, Vienna, Austria 3 Helwan University, Faculty of Science, Chemistry Department, Ain Helwan, Cairo, Egypt (Received June 16, 2008) Water hyacinth (Eichhornia crassipes) is known to accumulate elements from rivers and a good tool for water monitoring. To test the usefulness of such an aquatic plant as a bioindicator, we have determined the levels of Na, Ca, Cr, Fe, Co, Zn, As, Rb, Zr, Sb, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb, Hf, Ta, Th, and U in water hyacinth around industrial facilities and along the studied area by instrumental neutron activation analysis. The concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and Pb were determined in upstream river water and effluent factories. Contamination factor, and pollution load index was calculated. The results show that higher concentrations as well as bioaccumulation factors of these elements were observed in water hyacinth samples around the industrial facilities. On the other hand a decrease in calcium concentration was observed as a result of the thermal pollution of Nile river water. The pollution load index for the studied area was estimated to be 4.2. Introduction Environmental pollution has become a global concern. One of the major areas of concern in Egypt is the pollution of Nile river water by discharge from industrial facilities. Huge quantities of industrial effluents are discharged into the river. For example, the cement factory, located at Tura area, Cairo discharges 6.9 million cubic meters per year, that contain about 400 kg from both Zn and Pb, as well as, about of 200 kg Cu/year. 1 The excess of contaminants entering the aquatic environment change the balanced bioavailability and may enhance the toxicity to biological systems. Biotransformation by bacteria in the water–sediment interface can strongly influence elemental toxicity throughout the remaining food chain. For example, Hg, As, Sn, and Pb undergo biomethylation in the water– sediment interface, resulting in the production of more toxic species. 2 Thus environmental monitoring around the discharge points of the industrial facilities is necessary. Using biological indicators such as plants for monitoring both air and water pollution has been well established. Alga is a sensitive indicator of metal contamination in the aquatic environment. 3 Mosses have been used extensively to monitor atmospheric deposition of heavy metals and other trace constituents, 4 where chemical analyses of these bioindicators are much easier due to higher concentrations and strongly reduced contamination problem, 5 especially when using non destructive analysis technique such as instrumental neutron activation analysis (INAA). * E-mail: ashrafaly2001@yahoo.com It was reported that water hyacinth successfully absorbs and accumulates toxic elements from aqueous solutions. 6–11 It was also used as a scavenger of heavy metal pollutants in the Lake Chivero and its associated rivers in Zimbabwe. 12 The absorption mechanisms of these elements occur via the root system in substrate water that was contaminated and via the leaves that were exposed to atmospheric deposition. 11 ISMAIL et al. 1 determined Zn, Cu, and Pb in water hyacinth samples collected from selected sites and water bodies around greater Cairo. Results indicated that accumulation of the element in question is due to its loading inputs in the water body and water hyacinth is a good bioindicator candidate for river water monitoring. 1 ASHRAF ALY et al. 13 have concluded that water hyacinth is a good bioindicator and bioaccumulator for uranium in Nile river water and environmental impact of industrial facilities were successfully monitored. 13 In this work we studied the usefulness of water hyacinth as a bioindicator for environmental monitoring especially around factories discharging their liquid effluents into the Nile river. Water hyacinth, upstream water and water discharge effluents at the same site were collected from El-Saf city (south of Cairo) up to Rosetta (Rachid Branch) to estimate the relative accumulation in question due to its loading inputs in the water body. INAA was used to determine the concentration of Na, Ca, Sc, Cr, Fe, Co, Zn, As, Rb, Zr, Sb, Cs, La, Ce, Nd, Sm, Eu, Tb, Yb, Hf, Ta, Th, and U in water hyacinth. Concentrations of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and Pb in upstream water and discharge effluents of factories were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES).