The effect of the heavy metals lead (Pb²⁺) and zinc (Zn²⁺) on

Abstract

This investigation explored the effect of the heavy metals Pb (Pb 2+ ) and Zn (Zn 2+ ) individually and in combination (i.e. three metal solutions) on both the brood and larval development of the burrowing crustacean, Callianassa kraussi. Egg and larval mortalities at factorial (4x7) combinations of salinity (20, 24, 30, 35 mg/l) and seven respective metal concentrations were examined. The results provided various statistically significant trends. Individual concentrations of Pb and Zn at various salinities impacted negatively upon the brood and larval development of Callianassa kraussi. Increasing the specific concentrations of both metals further demonstrated a negative influence, especially on brood development and to a lesser extent on larval development of Callianassa kraussi. Comparing the toxicity of the three concentrations of metals to Callianassa kraussi brood and larval development, it was found that individual Pb concentrations exhibited the least mortality (LC 50 Pb-eggs-35ppm = 1.580 mg·l -1 whilst individual Zn concentrations displayed considerably higher mortality (LC 50 Zn-eggs-35ppm =0.066 mg/l) but that the combination of Zn and Pb concentrations produced the highest mortality =0.036 mg·l -1). Varying salinities in permutation with varying metal concentrations exhibited a significant detrimental influence on the brood and larval development of Callianassa kraussi, notably at the lowest salinities in combination with the highest metal concentrations.

Effects of Lead in white shrimp (Litopenaeus schmitti) metabolism regarding salinity

“…Lead occurs as an environmental contaminant in a wide range of chemical and physical forms which strongly influence its behavior and effects on the ecosystem being assimilated by organisms in the form of ions as much as in the form of complex. The presence of this metal in marine environment occurs as a result of processes such as erosion and soil leaching and they still appear ubiquitous from the precipitation of lead dust from the atmosphere due to its extensive use in paint industries, drums, pipe and additives in petroleum products and their environmental concentration varies from location to location 3,4 .…”

“…In its inorganic form lead is present in different oxidation states (0, I, II e IV), from which Pb 2+ is the most stable form among the ionic species, which leads to be thought of as the form in which this element is bioaccumulated by aquatic organisms 2,3 . Similarly, lead organic compounds known as neutral organometallic compounds, such as tetraethyl lead and tetramethyl lead, tend to be bioaccumulated by organisms because they are lipophilic (property that facilitates its movement through biological membranes) 2 .…”

“…Zagatto and Bertoletti 2 state that the toxicity of this metal ion is mainly due to its ability to infer in the metabolism (blocking, shifting the essential ion or modifying the active conformation) and also to its low mobility (they become gradually insoluble as the molecular mass increases) which causes them to build up, deeply modifying the metabolism of the organism. Jackson, et al 3 , reported that lead seems to be metabolized through the calcium channels and thus accumulates in skeletal tissues.…”

“…In recent years, several studies such as by Barbieri, et al 5,6,7,8,9 , have been conducted regarding the bioaccumulation of metals to determine toxicity in many species of organisms. In the case of shrimp, in addition to being a benthic species with non--pelagic larval stage, this organism is also considered great for toxicity studies 10 especially for high availability throughout the year, relatively low cost without counting on ease of handling, and also a great sensitivity to contaminants which carries great reliability and accuracy of the assessment of response to the pollutant even when working in short periods of exposure 3 . They are considered to be good water quality indices, with the ability to reflect the environmental deterioration before it reaches the population or community.…”

Alterations in the Leucocytes and Serum Biochemistry in grey mullet (Mugil cephalus L,) fingerlings Exposed to Sub lethal doses of Lead for different exposure periods

“…Lead(Pb) is one of the most widely used heavy metals that has wide applications in such products as storage batteries (lead accumulator), electric cable sheaths, alloys, pesticides, paints, petrol and rubber products among other uses [1] . In water bodies, Pb forms complexes with sediments or organic materials [2] .…”