Electrical conductivity as a tool for identification of metal contaminated fish protein

Biophysical, histological, and bioaccumulation properties of Tilapia muscle affected by water pollution with heavy elements and microbes at the El-Rahawy drain in Egypt

The leakage of sewage and agricultural drains has led to the contamination of freshwater branches with toxic heavy elements. This raises concerns about their toxic effects on aquatic ecosystems, especially on fish. Tilapia is regarded as an important protein source in Egypt and many other countries. The biophysical, nutritional, and histological aspects of water pollution in the El-Rahawy and Al-Qatta locations of the Nile on Nilotic tilapia muscle were evaluated by assessing the level of contamination of Nilotic tilapia fish. The current study showed that water of the Rosetta branch water was polluted with a very high level at El-Rahawy Drain discharge (RD) location, and with a high level at Al-Qatta (Q) location, while El-Rahawy (R) location was polluted with a lower level. The study traced the pollution effects on Tilapia (Nilotic) muscles in the previous locations. Bioaccumulation factor (BAF) showed a high value of all heavy metals in Tilapia muscle at the Q and R locations. Contrary to what was expected, discharge (RD) location contamination caused BAF increment of heavy metals in Tilapia muscles at upstream R location. All these results were compared with measured dielectric parameters of Tilapia muscle samples in the frequency range (0.02-1000) kHz. There was an increase in conductivity (σ_ac), dielectric constant (ε'), dielectric loss (ε″), penetration depth (dp), and dissipated power (PD) values of Tilapia muscle, with increasing pollution level. The values of permittivity at low and high frequencies (ε'_s & ε'_∞) for Tilapia muscle decreased by increasing pollution. Finally, the variation of these parameters, based on that proportionality relationship, can be considered as a physical indicator for fish contamination affected by their environment pollution, although these parameters need further studies in a controlled (qualitatively and quantitatively) polluted media.

Ecological and health risk assessment of potentially toxic elements in the major rivers of Pakistan: General population vs. Fishermen

Large amounts of potentially toxic elements (PTEs) have, and continue to be, released into the freshwater ecosystems of Pakistan. However, there is limited information available on the ecological risk of PTEs from sediments and fish consumption, for both the general population and fishermen, at the national scale in Pakistan. In this study, water, sediments and fish samples were collected from major rivers (Chenab, Upper Indus, Lower Indus and Kabul) across Pakistan and analyzed through Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Inductively Coupled Plasma Atomic Emission Spectroscopy ICP-AES and Atomic Fluorescence Spectrometry (AFS), respectively. Ecological risk analysis of sediments revealed that Cd posed a high ecological risk in the Upper Indus and Chenab, a considerable risk in the Lower Indus, and moderate risk in the Kabul. The target hazard quotient of As through fish tissue consumption exceeded safety levels for fishermen at all the rivers, where Cd exceeded at Upper Indus and Chenab, and Pb for Chenab fishermen only. For the general population, PTE ingestion through fish tissues was within the safety limits at all rivers. Meanwhile, the total target hazard quotient in all three rivers exceeded the safety limit, representing a high risk for the fishermen of Pakistan. The results show that ecological risk and target hazard quotient assessment not only provides valuable information for future research in terms of PTE contamination in the major rivers of Pakistan, but also all the metal pollutants from rivers finally reach to Arabian Sea, therefore might pose a risk to marine ecosystem at national and international scale.

Role of living environments in the accumulation characteristics of heavy metals in fishes and crabs in the Yangtze River Estuary, China

Correlation of heavy metals in the tissues of typical organisms (i.e., fishes and crabs) and those in their living environments (i.e., surface water, bottom water, and sediment) in Yangtze River Estuary has been qualitatively and quantitatively analyzed. Metal levels followed the trend: sediments > Eriocheir sinensis > Eriocheir leptognathus > benthic fish > pelagic fish > bottom water > surface water. Tissues in fishes and crabs of different species and sizes had diverse metal bioaccumulation characteristics, which was significantly affected by environment factors and their living habits. Metal levels in legs of crabs, and heads and skins of fishes showed significant correlations with those in their living environments. Collichthys lucidus is an effective bioindicator for assessing metal levels in water. No significant health risk was identified by the estimated daily intake and target hazard quotients analyses.