Presented By: Department of Environmental Science and Technology, Institute of Science and Technology for Advanced Studies and Research (ISTAR), Vallabh Vidyanagar Vidyanagar,, 388120, Gujarat, India
Contamination of the aquatic environment by the heavy metals has become a serious concern in the developing world(mishra and Tripathi, 2008). The plants act as samplers, accumulating pollutants to a higher concentration than their surroundings (Zurayk et al, 2001). Trace metal concentrations have been studied in some plant species, but data on their concentrations in different parts of the plants are scanty, especially in the aquatic macrophytes (Baldantoni et al, 2005).
To assess the heavy metal contamination like Cr, Pb, As and Cd in plant components (roots, stems, leaves, flowers) of four native aquatic macrophyte species Nelumbo nucifera Gaerth, Typha angustata Bory & Chaub, Ipomoea aquatica Forsk and Hydrilla verticillata (L.f.) Royle, in comparison with sediment and water samples in two distinct season. As the macrophytes concentrate/ accumulate huge amount of various contaminants (e.g. metals) and are consequently useful indicators of locall pollution.
STUDY AREA
SUMMERS MONSOONS
Field Work Water and Sediment Collection Plant Collection Laboratory Work Data Analysis
RESULTS
Heavy metal concentration ti of sediments and water and ratios between concentration of sediments and water. Element Summer Monsoon Sediment Water Sediment/ Sediment Water Sediment/ mg kg -1 mg L -1 Water mg kg -1 mg L -1 Water w/w w/w Cr 76.29 0.90 84.77 36.26 0.51 71.52 Pb 8.33 0.40 20.83 5.88 0.10 58.80 As 2.42 0.09 26.86 1.64 0.03 54.67 Cd 1.99 0.05 39.80 0.67 0.01 67.00
Mean plant heavy metals concentration (mg kg -1 ) during summer (A) and monsoon (B) season 1 Cr mg kg 100.00 90.00 80.00 70.0000 60.00 50.00 40.00 30.00 20.00 10.00 000 0.00 A 300.00 B 18.00 9.00 16.00 8.00 250.00 14.00 7.00 200.00 12.00 6.00 10.00 5.00 150.00 4.00 8.00 300 3.00 100.00 600 6.00 2.00 4.00 50.00 1.00 2.00 000 0.00 000 0.00 000 0.00 1 2 3 4 Plants Cr Pb As Cd 1 Pb, As, Cd mg kg 1 Cr mg kg 1 2 3 4 Plants Cr Pb As Cd Pb, As, Cd mg kg 1 (1 = N. nucifera Gaerth., 2 = T. angustata Bory & Chaub, 3 = I. aquatica Forsk. and 4 = H. verticillata (L.f.) Royle)
Concentration factor(c.f.) calculated for the various species and elements during summer season. Plants Cr Pb As Cd Mean Nelumbo nucifera 104.74 11.30 92.11 2.48 52.66 Typha angustata 41.51 16.51 93.51 10.68 40.55 Ipomoea aquatica 19.44 19.74 49.49 2.76 22.86 Hydrilla verticillata 30.49 10.57 10.0000 136 1.36 13.1010 Mean 49.04 14.53 61.28 4.32 SD 38.21 4.37 39.82 4.28
Concentration ti factor(c.f.) calculated l for the various species and elements during monsoon season. Plants Cr Pb As Cd Mean Nelumbo nucifera 279.20 450.35 265.77 18.7 253.50 Typha angustata 139.48 253.97 243.03 40 169.12 Ipomoea aquatica 510.60 874.02 529.43 32.2 486.56 Hydrilla verticillata 15.47 10.40 107.50 11.2 36.14 Mean 236.19 397.19 286.43 25.53 SD 212.30 365.29 176.42 12.99
Mean root heavy metal concentration (mg kg -1 ) during summer (A) and monsoon (B) season 1 Cr mg kg 45.000 A 8.000 140.000 B 90.000 40.000 7.000 120.000 80.000 35.000 6.000 70.000 30.000 100.000 5.000 60.000 25.000 80.000 4.000 50.000 20.000 40.000 3.000 60.000 15.000 30.000000 10.000 2.000 40.000 20.000 5.000 1.000 20.000 10.000 0.000 0.000 0.000000 0.000000 1 2 3 1 2 3 Plants Plants Cr Pb As Cd Cr Pb As Cd Pb, As, Cd mg kg 1 kg 1 Cr mg k Pb b, As, Cd mg kg 1 (1 = N. nucifera Gaerth., 2 = T. angustata Bory & Chaub and 3 = I. aquatica Forsk.)
Mean shoot heavy metal concentration (mg kg -1 ) during summer (A) and monsoon (B) season g 1 Cr mg kg 14 A 3 120.000 B 16.000 12 10 8 6 4 2 0 2.5 2 1.5 1 0.5 Pb b, As, Cd mg kg 1 g 1 Cr mg kg 100.000 80.000 60.000 40.000 20.000 14.000 12.000 10.000000 8.000 6.000 4.000 2.000 0.000 0.000 0 1 2 3 1 2 3 Plants Plants Cr Pb As Cd Cr Pb As Cd (1 = N. nucifera Gaerth., 2 = T. angustata Bory & Chaub and 3 = I. aquatica Forsk.) kg 1 As, Cd mg Pb,
Mean heavy metal concentration (mg kg -1 ) in leaves during summer (A) and monsoon (B) season kg 1 Cr mg k 40 A 2.5 45.000 B 5 35 40.000 4.5 2 4 30 35.000 30.000 3.5 25 1.5 3 20 15 10 5 0 1 2 3 Plants 1 0.5 0 b, As, Cd mg kg 1 P Cr mg kg 1 25.000 20.000 15.000 10.000 5.000 0.000 1 2 3 Plants Cr Pb As Cd Cr Pb As Cd 2.5 2 15 1.5 1 (1 = N. nucifera Gaerth., 2 = T. angustata Bory & Chaub and 3 = I. aquatica Forsk.) 0.5 0 mg kg 1 Pb, As, Cd
Mean floral heavy metal concentration (mg kg -1 ) d i (A) d (B) during summer (A) and monsoon (B) season 10 Cr, As, Pb, Cd mg kg 1 8 6 4 2 A 1 Cr mg kg 6.8 B 6.6 64 6.4 6.2 6 5.8 2.500 2.000 1.500 1.000 0.500 Pb, As, Cd mg kg 1 0 Nelumbo nucifera 5.6 1 Plants 2 0.000 Cr Pb As Cd Cr Pb As Cd (1 = N. nucifera Gaerth and 2 = T. angustata Bory & Chaub)
Ranges of heavy metals contents and toxicity status in the tested plant species, compared with normal and critical ranges in plants during summer season Element Mean Range Normal Critical Toxicity ppm Range* Range* Status ppm ppm Cr 17.50 94.27 00314 0.03-14 5-30 Citi Critical Pb 4.23-7.9 0.2-20 30-300 Normal As 0.9-8.42 0.02-7 6-20 Critical Cd 0.07-0.53 0.1-2.4 5-30 Normal * Data after Maiti,2003
Ranges of heavy metals contents and toxicity status in the tested plant species, compared with normal and critical ranges in plants during monsoon season Element Mean Range Normal Critical Toxicity ppm Range* Range* Status ppm ppm Cr 784 7.84-258.8787 00314 0.03-14 5-30 Citi Critical Pb 1.04 87.40 0.2-20 30-300 Critical As 3.23-15.88 0.02-7 6-20 Critical Cd 0.11-0.4 0.1-2.4 5-30 Normal * Data after Maiti,2003
Correlation coefficient i between concentrations ti of heavy metal-pairs in root, stem and leaf systems of plant species. Medium Correlation (r = 0.5-0.7); High Correlation (r = 0.7-0.9); Very High Correlation (r >0.9). Analyzed Correlation coefficient (r) Metal Summer Monsoon Root Shoot Leaf Root Shoot Leaf System System System System System System Cr x Pb -0.700 0.841-0.404 0.981-0.247-0.982 Cr x AS 0.109 0.984 0.261 0.924 0.877 0.436 Cr x Cd -0.837 0.150 0.987 0.882 0.667 0.979 Pb x As -0.787 0.733 0.777 0.989-0.683-0.600 PbxCd 0.194 0.661-0.252 0.956-0.886-0.923 As x Cd 0.453-0.026 0.413 0.995 0.943 0.245
BIOMONITORS SUMMER Cr (Nelumbo > Typha > Hydrilla) Pb (Ipomoea > Typha> Nelumbo) As (Ipomoea > Typha > Nelumbo) MONSOON Cr (Ipomoea > Nelumbo > Typha) Pb (Ipomoea > Nelumbo > Typha) As (Ipomoea > Nelumbo > Typha) Based on the above results, it was revealed that the three native aquatic plant species (Ipomoea, Nelumbo and Typha) accumulate heavy metals in much higher concentrations. Such aquatic macrophytes py could also be used as "biomonitors / biofilters" as compared to other native aquatic macrophyte species, (Baldantoni et al, 2005 and Nirmal Kumar et al, 2006).
FINDINGS AND CONCLUSION Toxicity status of Cr is highest amongst all studied elements. I. aqautica appears to be the best heavy metal accumulator and monitoring species due to their availability throughout the year the wetland. During summer, most of the metals were higher in rooted plants like N. nucifera followed by T. angustata due to gradual settlement of metals in warmer days. In monsoon due to accumulation of more run off water from catchment area in Varasda wetland where much branched root system of free floating plants I.aquatica uptake high metals very actively.
ACKNOWLEDGEMENT One of the authors is highly thankful and grateful to UGC, for providing financial assistance.