Patterns of Trace Metals Accumulation in Different Trophic Levels of Lake Kailana, Jodhpur (India)

Transcription

1 Sengupta, M. and Dalwani, R. (Editors). 28. Proceedings of Taal27: The 12 th World Lake Conference: Patterns of Trace Metals Acmulation in Different Trophic Levels of Lake Kailana, Jodhpur (India) Devendra Mohan, Anil Chaudhary and Shalini Gaur Jai Narain Vyas University, Jodhpur, DRS ZSI, Jodhpur, Rajasthan Shalini Gaur : D/O Sh. O.D.Gaur, 15/7, Lal Maidan, Paota C Road, Jodhpur-3421 ABSTRACT Metals are found naturally in open waters and affect the aquatic fauna. Some of them are very essential in biological processes but high concentrations can badly affect trophic levels in the food chain of any ecosystem. An attempt was made to study the acmulation of Zn, Cu, Pb and Cd in the food chain of Kailana lake, Jodhpur. The mean concentration of Zn, Cu, Pb and Cd was.7mg/l,.2 mg/l,.25mg/l and.1mg/l respectively in the water of lake Kailana. Highest Concentration of Zn was found in Dragon Fly naid (.2982mg/gm ) and lowest (.136mg/gm ) in Vivipera gastropod. Cu was found highest (.1855 mg/gm ) in the Chironomid larva and was lowest (.28mg/gm body wt.) in fish. Pb was found highest (.169mg/gm ) in Chironomid larva and lowest (.22mg/gm ) in gastropod and fish. The data did not show any regular pattern of metal deposition at different trophic levels. Although all the organisms were exposed with the similar concentration of metals in water but depending upon their food habits, niches and some other metabolic processes acmulation of trace metals in their body was different. Organisms which depend upon the sediments had higher concentrations of metals. Some animals do not take metals directly but act as ecological amplifiers and acmulate high concentrations of metals for their predators which consume them in a large number. This can multiply the concentration of toxicant up to the highest trophic level. On the other hand some animals encourage the intake of high concentration of metals but minimize their efficiency metabolically by converting them in derivatives of less toxicity. Keywords: Trace metals, trophic level, water, Lake, Rajasthan. INTRODUCTION Most metals ocr naturally in open water, in very low concentrations. Some of these are known to be essential in biological processes. However in some fresh water ecosystems the metals concentration exceeds natural level due to human interference. In aquatic environment metals are not removed rapidly, nor are they readily detoxified, as a result they acmulate in the vital organs of the animals and plants (Rainbow and Moore 1986: Anderson and Brower 1978). Due to the bioacmulation, metals become a threat to the biological functions in the ecosystem. Extensive literature exists pertaining to the contents and uptake of trace matels by aquatic and terristial biota (Skinner et. al., 1978). Comparatively only a few studies have been carried out on the distribution of trace heavy matels in the aquatic food chain. These studies usually involve analyais of only a few selected species at various tropic levels and generally show that metals acmulate in biota, above ambient water level. Martin and Coughtrey (1976) reported that metals concentrations increased with higher trophic levels but Namminga et. al. (1974), Mathis and Cumming (1973) did not find such patterns. The objectives of this study is to determine concentrations of Cu, Pb, Zn, and Cd from different trophic levels of a fresh water Lake Kailana. MATERIALS AND METHODS samples were collected from the proposed lake column and bottom samples were collected by Vandorn water sampler, While the surface samples were collected in 3ml. polythene bottles from different sampling stations. 2ml. AR grade Nitric acid was added to each sample to preserve the samples then carried to the laboratory and filtered by Whatman filter paper No. 42. The samples of all depths from each station were mixed and analysed by Atomic absorption spectrophotometer. Filamentous algae, Fresh water shrimp, Chironomid larva, Dragon fly naid, gastropod () were collected by hand and cast nets from the lake kailana. Dry ashing technique modified by Middleton et. al.,(1973) was adopted for the proposed metal estimation in different tissues. Each dried body sample was ashed in muffle furnance at 45 o C for 12 hrs. The resulting ash was dissolved 2:1 perchloric acid and double distilled water for the complete digestion of the body samples. The mixture was then filtered by Whatman s ashless

2 filter paper no. 42 into a 25ml. volumetric flask and the volume in the flask was made up to 25ml. by adding double distilled water. The digested samples in aqueous solution were analyzed for Cu, Pb, Zn, and Cd using Flame Emission spectrophometer model AA Aircetylate flame was used in each case (APHA, 1985). Values were corrected for sample preparation losses. RESULTS AND DISCUSSIONS Table -1 gives the concentrations of the trace matels in different trophic lavels. The general trend of the acmulation of trace matels in the fish (Puntius sophore), gastropod (), Dragon fly naid and Chironomid larva (Fig. 6, 8 & 9) was Zn, Cu, Pb, Cd, while in glass fish () it was (Fig.-5) Zn, Pb, Cu, Cd. In the algae (Fig.-5) and shrimp (Fig.-7) the Cu concentration was not detectable and the trend remained Zn, Pb, Cd. Among the studied groups dragon fly naid, had the highest.2982 weight and gastropod had the lowest.136 weight of Zn concentrations. Bryan (1976), stated that the absorption of metals involves passive diffusion in most of the animals through the body surface and their binding in the body fluid, surface cells and internal organs. This pattern appears to hold true for Fishes (Peentreath 1973 a) and Amphoid crustaceans (Rainbow and Moore 1986) & Figure 6. Comparison of trace metals acmulation in & 28% 18% % 54% Figure 8. Comparison of trace metals acmulation in 374

3 26% % 44% 3% Figure 9. Comparison of trace metals acmulation in Chironomid Larva & *Concentration of copper in Filamentous algae could not be detected Figure 5. Comparison of trace metals acmulation in & % 4% 1% 95% *Concentration of copper in could not be detected Figure 7. Comparison of trace metals acmulation in 375

4 Table 1 Concentrations of different trace metals in different trophic levels of fresh water Lake Kailana, Jodhpur (Rajasthan). S. No. Metal In mg / lt. Filamentous Algae Fish Chanda Puntius nama sophore Gastropoda Vivipera bengalensis Crustacean Insecta Dragon Chironomid Fly larvae 1. Zinc Copper Led Cadmium The higher concentrations of Zn in Dragon fly naid might have appeared due to their carnivorous feeding habits. Young (1974) stated that food is more important source of trace metals acmulation than water in different animals. In the case of Algae Zn concentration was.253 mg/gm body wt (Fig.1). Davis 1973) showed the kinetics of Zn uptake by the rapid absorption of Zn into the cell membrane followed by diffusion controlling the rate of uptake and binding the protein within the cell and also during the growth cycle. along with the organic material by the detoxification mechanism. Cu and Zn are essential trace elements and act as components of metalloenzymes (Fisher, 1975). Additionally Cu is the metal in haemocynin of some invertebrates (Hoar, 1966) therefore, some physiological control of these metals is probably possible. Concentration of Pb was highest in the chironomid larvae and the lowest in the gastropod (Fig3). The higher level of in the chironomid larva may be due to its benthic habitat and detritus feeding habit Figure 1. Concentration of zinc in different trophic The higher level of Cu concentration in chironomid larvae.1855 mg/gm and dragon fly naid.1581 dry weight was observed (Fig.2). This might be due to their benthic habitat and detritus feeding habit. In shrimps the Cu concentration was not detectable. Rainbow and Moore (1986) reported that Crustaceans employed different physiological strategies to avoid toxic effects while acmulating the trace elements and regulating the essential metals like Zn and Cu. Similar capacities of crustaceans have been reported by Bryan (1976). In Algae concentration of Cu was not detectable. Anderson (1978) found lower concentration of Cu in benthic algae, while a higher concentration of the same in phytoplanktons was observed by Namminga et. al., (1974). Mandallie (1969) studied the uptake of Cu in marine phytoplankton and suggested that may be excreted * Concentration of copper in Filamentous algae and could not be detected Figure 2. Concentration of Copper in different trophic Figure 3. Concentration of Led in different trophic 376

5 Fig: 4 Concentration of Cadmium in different trophic Leland and Mc Nurney (1974) stated that acmulation of Pb by macroinvertebrates and fishes depend upon the habitat as the animals burrow or ingest sediments, show higher concentration of Pb. Algae showed a relatively higher concentration of lead. Schulz-baldas and Lewin (1976) reported that algae can acmulate Pb over long periods even when its contents are low in water. Among the fishes, showed higher acmulation of metals which may be due to their herbivorous feeding. Considering the fluctuation range of metal enrichment in different trophic levels of Lake Kailana no general pattern has been determined for the investigated metals in various plants and animals however algae can store more heavy metals even when the contents in water are low. Sediments depending organisms had higher metal concentrations then other biota. Carnivorous fish have lower metal acmulation than herbivore fish. An interpretation can be drawn that metal fluctuates considerably according to different dietary habitats. Hoar WS (1966) General and Comparative physiology. Prantice Hall N.J Lenad H. V. and Mc Nurney J. M. (1974) Lead transport in a river ecosystem. Paper presented in an International Conference on Transport of persistant chemicals on Canada. Mandelli E. F. (1969) The inhibitory effects of copper on marine phytoplanktons, Marine science, University of Texas. 14: Martin M. H. and Coughtrey P. J (1976) Comparisons between the levels of lead, zinc and cadmium within a contaminated environment, Chemosphere 5: 15-2 Mathis B. J. and Cummings T. F. (1973) Selected metals in sediments, water and biota in the Illinois river. J. water pollut. Control. Fed. 45: Middleton S. G., Gillis F. E. and Grau J. G (1973) Praparation of insect specimens for analyses by means of atomic absorption spectrophotometry. Ent. SOC AM 66: Namminga H. E., Scott J. E. and Burks S. L. (1974) Distribution of Copper lead and zinc in selected components of a pons ecosystem. Proc Oklahoma Acad sci 54: Pentreath R. J. (1973a) The acmulation and relation of 65ZN and 54MN by the Pleuronectes platessa L. Journal of experimental Marine Biology and Ecology. 12: Rainbow P. S. and Moore P.G.(1986) Comparative metal analysis in amphipod crustaceans. Hydrobiologia 141: Schulz-Baldes M and Lewin R. A. (1976) Lead uptake in two marine phytoplankton organisms. Biol. Bull. 15: Skinner S.P, Gentry J.B. and Giesy J.P. (1978) Cadmium dynamics in terrestrial food webs of coal ash basin. Environmental Chemistry and Cycling processes. DoE Symposium Series Young M. L. (1974) The transfer of 65 Zn and 59 Fe along two marine food chains. Ph.D. thesis. University of east Angila.4 ACKNOWLEDGEMENTS Authors are highly indebted to Dr. Rajeev Gupta, Head Dept. of Zoology, J.N.V. University, Jodhpur for providing all the facilities regarding the work. REFERENCES Anderson RV and Brower (1978) Pattern of trace metal acmulation in Cray fish population. Bull. Envron contran Toxicol. 2: Apha Awwa WPCF (1985) Standard methods for the examination of water and waste water. APHA AWWA WPCF 16 th Edition Washington Bryan G.W. (1976) Heavy metal contamination in the sea. In: Marine Pollution. Johnston, R (ed) academic press London Davies A.G. (1973) Radioactive contamination of the Marine Environment International Atomic energy Agency, Vienna Fisher G.L. (1975) Function and Homeostasis of copper and zinc in mammals. Sci. Total Environ, 4: