Sultan Marsh is one of the largest and most important wetlands in Turkey, Middle East and Europe, embodying saline and fresh water ecosystems, which provide a shelter for 426 bird species. The area has begun to contribute much to the tourism of Kayseri state and its environs. However, the sites in the vicinity of the sewerage-sludge and fertilizer plants are highly damaged due to pollution. As such, studies on the heavy metal status of water, sediment and plants were investigated. Concentrations of iron and manganese were measured in bottom sediments, water and Phragmites australis, Typha angustifolia, Potamogeton pectinatus, Ranunculus sphaerosphermus and Groenlandia densa in Sultan Marsh. Analyses of water, bottom sediments and plant samples indicated that all sampling sites in the study area basin are generally more or less polluted when compared with the control sites. It has been found that the tissues of P. pectinatus accumulated heavy metals more than those of G. densa. Therefore, all plants can be used as biological indicators while determining environmental pressures; however, Phragmites australis has proved more appropriate for such studies. (c) 2005 Elsevier Ltd. All rights reserved.