Pakistan Journal of Biological Sciences

Year: 1998 | Volume: 1 | Issue: 4 | Page No.: 332-334
DOI: 10.3923/pjbs.1998.332.334

Aquatic Macrophytes as Biological Indicators for Pollution Management Studies. IV: Effect of Salts present in Factory Effluent Water on Chemical and Biochemical Composition of Eichhornia crassipes and Pistia stratioites

M. Niaz and E. Rasul

Abstract: The experiments were conducted in artificially constructed water ponds during the months of May-July, 1994. Both the macrophytes were treated with different concentrations of salts commonly used in textile processing units. Chemical and biochemical analyses were made at the end of the experiment. Na⁺ concentration of the aqueous medium was more crucial. Which also interfered with the Ca²⁺, Mg²⁺ and K⁺ percentage of the plant. There was a positive correlation of concentrations in the aqueous medium and their accumulation in the case of Na⁺ and CI‾ . Nitrogen in aqueous medium increased the crude protein status at lower levels of treatment.

Keywords: Eichhornia crassipes, Pistia stratioites, Chemical analysis, Factory effluents, water hyacinth and water lettuce

Introduction

Indiscriminate use of various inorganic salts during different industrial processes at manufacturing/processing units has posed a serious threat to our water flora, as majority of the units dispose off untreated effluents. These injurious factors have played havoc with phytoplankton in water pools, which, in turn, have interfered with all natural food chains and food webs. Original landscape of this region had been changed drastically during the last few decades. The situation is so grave that population of even large hydrophytes have now become affected due to the presence of deleterious salts in the effluent water.

The response of various species to stressed conditions varies greatly and is specific to a particular index of disturbance in environment (Hanif and Davies, 1998).

Eichhornia crassipes (water hyacinth) and Pistia stratioites (water lettuce) are aquatic weeds. The cover of both these plants took up metabolic ions from rooting medium (Foster and Warshall 1991). Studies on the accumulation of ions within their bodies can depict the extent of pollution in vicinity of rooting medium (Ashraf and O'Leary, 1997).

The differential responses of E. crassipes and P. stratioites to various salts make them suitable candidates under various polluted aquatic ecosystem, i.e., according to the chemical nature of the affluents contributing to the water body.

The situation is still rectifiable but an exhaustive study covering all the aspects of this toxicity exudation and its control is a pre-requisite. For proper toxicity management of our water bodies both conventional and non-conventional approaches have to be adopted. The present study is an attempt to adopt a non-conventional approach by studying the ionic interference of rooting medium with chemical and biochemical status of plants.

Materials and Methods

Experiments were performed at Botanical Gardens, University of Agriculture, Faisalabad. Plants were grown in artificially constructed polyethylene lined ponds (2 ft x 2 ft with uniform depth of 9 inches). Each ponds was filled with 35 liters of solution having 0, 100, 500 and 1000 ppm concentration of NaCI, NH₄CI, NaHCO₃, Na₂CO₃, CaOCl₂ and NH₄NO₃. Plants were harvested after period of three months and dried to determine their chemical composition for Na⁺, K⁺, Mg²⁺, Ca²⁺, CI‾ and total-N.

The N_a⁺ and K⁺ were determined with flame photometer, Ca²⁺ and Mg²⁺ with atomic absorption spectrophotometer. While CI‾ with chloride analyzer (Yoshida et al., 1976) the total-N was determined using microkjeldahl method (Jackson, 1962). The data were subjected to statistical treatment using Minitab package programme (Minitab, 1989) and treatment means were compared using Duncan's Multiple Range Test.

Results

Data regarding the effect of various salts with varying concentrations on the chemical composition of E. crassipes and P.stratioites have been given in Table 1. There were statistically significant differences among the ionic concentrations in both the plant species, under different salt treatments. Calcium composition was adversely affected by the application of all the salts. With the increasing concentrations of salts, Ca (%) in the plant tissues followed a decreasing order in NaCI or NH₄NO₃ treatments. Whereas the reverse effect was observed in NH₄CI treatment, though more percentage of calcium was observed in control. The composition of Mg²⁺ and K⁺ was affected likewise due to the competition of these cations with Na⁺.

Crude protein composition on whole plant basis was calculated for both the plants and is presented in Table 2. This biochemical parameter is an important indicator of any plant species for its nutritional value. An apparent look at these tables indicated that dry matter of E. crassipes had greater crude protein contents than P. stratioites, so was found to be better candidate species as far as its fodder value was concerned. CaOCI₂ showed a similar protein depleting trend in both the plants. While there was a positive correlation between nitrogen source and the crude protein values in E. crassipes. In case of P. stratioites, single N-source salt showed a similar trend as was found in E. crassipes. However, nitrogen contents did not increase when the plants were exposed to NH₄NO₃ and crude protein contents did not enhance appreciably.

Discussion

The aqueous solution around root zone was also found to have a major role in the distribution/presence of various ions within plant body. Ca²⁺ %age in plant body was adversely affected by the application of Na⁺- salts especially at higher concentrations. Na⁺ -salts also had an antagonistic relations with K⁺ and Mg²⁺ %age in plants. The application of CI‾ was found to be proportional to the CI‾ (% age) of the plant material. However, Cl interfered with the NH₄⁺ or NO₃ and NH₄CI applications in both the plants. P. stratioites was found to be more tolerant of Na⁺ as Ca²⁺ and Mg²⁺ contents were less affected in this hydrophyte.

Lynch and Lauchli (1985) proposed that Na⁺ may inhibit the radial movement of Ca²⁺ from external solution to the root xylem by screening of cation exchange sites in the apoplast. Sodium induced Ca²⁺ deficiencies have also been observed by Grieve and Maas (1988) and Maas and Grieve (1987). As the activity of Na⁺ in the substrate increases, the system becomes less discriminating and the selectivity for Ca²⁺ is impaired (Suarez and Grieve, 1988).

The composition of Mg²⁺ and K⁺ was affected likewise due to the competition of these cations with N_a⁺. Ashraf and O'Leary (1997) reported similar results and are of the opinion that uptake of cations in plant tissues is directly correlated with the concentration of the surrounding medium. Jung et al. (1987) reported inverse proportion of (K⁺ percentage in plants and NH₄⁺ nitrogen in the aqueous nedium around roots. Ashraf and O'Leary (1995) and (1997) reported and similar trend of anion and cation distribution after exposure to Na⁺ salts.

The effects on total crude protein contents and the problems of growth suppression could he linked with the studies of Costa et al. (1992) and Varanasi et al. (1992). Sodium salt had reduced the N-uptake by the plants. So the crude protein contents_. decreased with these salts. These results are in line with the results of Jilani et al. (1992).

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