'Real-world' contaminant exposure of sediment-dwelling biota is typically long-term, low-level and to multiple pollutants. However, sediment quality guidelines, designed to protect these organisms, relate only to single contaminants. This study uses radiometrically dated sediment cores from 7 English lakes with varying contamination histories to reconstruct temporal changes in likely risk to bi...

Title of Dissertation: THE IMPORTANCE OF PHYSICAL MIXING AND SEDIMENT CHEMISTRY IN MERCURY AND METHYLMERCURY BIOGEOCHEMICAL CYCLING AND BIOACCUMULATION WITHIN SHALLOW ESTUARIES Eun-Hee Kim, Doctor of Philosophy, 2004 Dissertation Directed By: Professor Robert P. Mason, Marine Estuarine Environmental Science The objective of this study was to examine, using mesocosm experiments, the long-term ef...

We measured the level of heavy metal accumulation in lake sediments, herbivorous (Oreochromis niloticus) and carnivorous (Serranochromis thumbergi) fish, and crayfish (Cherax quadricarinatus) from Lake Itezhi-tezhi (ITT) and Lake Kariba. We used atomic absorption spectrophotometry to quantify the levels of seven heavy metals (Cr, Co, Cu, Zn, Cd, Pb, and Ni). The sediment and the herbivorous fis...

Passive equilibrium samplers deployed in two or more media of a system and allowed to come to equilibrium can be viewed as 'chemometers' that reflect the difference in chemical activities of contaminants between the media. We applied silicone-based equilibrium samplers to measure relative chemical activities of seven 'indicator' polychlorinated biphenyls (PCBs) and hexachlorobenzene in eels and...

Organochlorine (OC) insecticides were measured in different environmental compartments (including seawater, sediment, and biota) at six sites within the Mai Po Marshes Nature Reserve (MPMNR) and at one site in A Chau (AC) in Hong Kong in June 2002 (wet season) and January 2003 (dry season). MPMNR is a Wetland of International Importance (Ramsar site) situated in the western part of Hong Kong, w...

Arsenic (As) and mercury (Hg) are among the most toxic metals/metalloids. The overall goal of this study was to investigate the bioaccumulation of these trace elements in Vallisneria neotropicalis, a key trophic species in aquatic environments. For this purpose, As and Hg concentrations were determined in sediments and natural populations of V. neotropicalis in sub-estuaries of Mobile Bay (Alab...

Glyphosate is the most widely used herbicide worldwide. However, there are some uncertain aspects with respect to its environmental fate. To evaluate the existence and distribution of this pesticide and its metabolite, aminomethylphosphonic acid (AMPA), their presence in fresh water, sediment, and suspended particulate matter (SPM) was measured in samples collected in a river running across a l...

Microbial growth within the water-saturated subsurface environment was investigated by exposing sandy sediments to groundwater for 12 weeks at a depth of 10 or 20 m in a stainless-steel groundwater well. Washing and heating the sediment to 600 degrees C (removal of organic carbon) prior to the exposure did not prevent the natural microbial community from colonizing the sterilized sediment sampl...

in this study, the concentrations of heavy metals (ca, zn, cu, fe, mn, ni) in thesediment of shavoor river in khuzestan province in iran has been investigated. after the library studies and field studies, six samples of water and sediment were taken from the river in order to evaluate heavy metal pollution in sediments. to determine the geochemical phases of metals in sediment samples the 5-ste...