作者:S.Stegen    文章来源:本站原创    点击数:    更新时间:2008-9-12


The species Zannichellia palustris and Myriophyllum acuatium, collected along the Loa River basin, North Chile, were chosen as possible bioindicators for Cd, Pb, and Cu. These species have a cosmopolitan distribution and can survive very sudden and large fluctuations in salinity. They are widely spread in Chile and in spite of their enormous salt tolerance they seldom penetrate to the marine habit.

Quantification in water and algae samples was made by Differential Pulse Anodic Stripping Voltammetry (DPASV) after UV (water) and open wet digestion (algae). The cadmium concentrations found in algae samples ranged from 0.72±0.01 to 32±0.31 µg/g d.w. Values for lead were less and estimated 0.4±0.01 to 2.13±0.08 µg/g d.w.. Copper concentrations were between 13±0.2 and 119±0.5 µg/g d.w.. In comparison with the element concentrations in the water samples, a significant biomagnification, especially for cadmium in Myriophyllum acuatium was observed.

Keywords: river water plants, bioindicator, heavy metals, North Chile, Loa river


Las especies Zannichellia palustris y Myriophyllum acuatium recolectadas a lo largo de la Cuenca del Río Loa, fueron escogidas como posibles bioindicadores de Cd, Pb y Cu. Estas especies tienen una distribución cosmopolita y pueden tolerar súbitamente grandes fluctuaciones de salinidad. Se encuentran ampliamente distribuídas a lo largo de Chile y a pesar de su enorme tolerancia a la sal, raramente penetran en el habitat marino.

La cuantificación en las aguas y algas se realizó mediante la técnica electroanalítica de Voltamperometría Diferencial de Pulso con Redisolución Anódica (DPSAV), tras una mineralización por UV para las aguas y húmeda de sistema abierto para las algas. La concentración encontrada para cadmio en las muestras de algas fluctúan entre 0.72±0.01 y 32±0.31 µg/g p.s. y para Cu, entre 13±0.2 y 119±0.5 µg/g p.s. En comparación a la concentración de los elementos encontradas en las aguas, se observó una significativa biomagnificación, especialmente para Cd, en la especie Myriophyllum acuatium.

Palabras claves: plantas acuáticas de río, bioindicador, metales pesados, norte de Chile, Río Loa.


The concept of a bioindicator is applied to those organisms that are able to accumulate substances considered as contaminants, without being themselves greatly affected. The process through which the organism concentrates a substance to levels greater than the environment is known as bioaccumulation. 1, 2) Each organism has a different optimum life range. For example, those species with a wide tolerance range should be able to cope with environmental alterations more easily. These organisms are the bioindicators of an altered environment.

The factors considered for the bioindication process (via element accumulation) depend greatly on the bioindication method used. The two main bioindication methods are the "in situ" or passive method (the plant grows in the area studied) and the so-called indirect or transplantation method (plants are transplanted and exposed to a study area for a certain time span). This paper is based on the first bioindication method.

In general, a bioindicator must be sensitive to environmental changes. The quantification of a pollutant, indicated by the experimentally collected data, changes the bioindicator into a biomonitor, relative to the quantification of the parameter studied.

In the water, nutrients are always available for plants. Therefore, when the amount of mineral nutrients increases, water plant growth may be very fast. However, the toxic compounds contaminating the water are also available for plants and may cause death in some cases.

Physiologically, water plants are different from ground plants because they absorb nutrients through all the submerged area and, they can extract carbon dioxide from the bicarbonate dissolved in the water by photosynthesis. Many undergo a serious reduction of the vegetative body during unfavorable periods. Due to their relatively long life cycles, their permanent existence, and their tolerance to different environmental impacts, etc., vegetable species from water environment, both sea and river, have been commonly reported as the major contamination indicators. 3,4)

The chemical composition of river waters in North Chile is influenced by two main conditions: the saline environment, which explains the high concentration of major elements 5,6,7) and volcanism, which is related to the presence of several volatile trace elements. 8,9)

The metals studied here were lead, cadmium and copper. These elements show a great affinity with certain functional groups (particularly SH-groups of proteins) and act, directly or indirectly, interfering with different metabolic processes 10). These metal-thionines are found in human beings, animals, simple organisms and even in major plants 10,11). Copper is also an essential micronutrient for most plants and it takes part in several metabolic processes. It has been shown that the lack of copper may influence many physiological processes. On the other hand, copper becomes toxic for water plants at higher levels 12).

This research was aimed first at implementing a reliable analytical methodology and, in the second stage, the quantification of potentially ecotoxic heavy metals, especially Cd, Pb, and Cu in water and water plant samples from the Loa River basin in North Chile.

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