The oxidation-reduction potential (Eh) of water can be calculated from the pH, partial pressure of oxygen (PO2) dissolved in water, and the normal oxygen electrode potential E0. It was estimated by a Digital pH Redox Meter- CORNING MODFL- 3, AND HANNA INSTRUEMENT. It was also estimated by following deduction methods (Gautam 1990). The result was expressed in m volt.
OXIDATION REDUCTION INDEX (rH2)
Oxidation Reduction Index (rH2) was estimated by deduction of data of Eh by following Gautam (1990).
FREE CARBON DIOXIDE (CO2) IN WATER
Free carbon dioxide (CO2) was determined by titration of water samples with N/44 sodium hydroxide solution (NaOH) using phenolphthalein as an indicator (Welch 1948). The results were expressed in mg. of CO2 per liter (mg/l) of water.
BICARBONATE (HCO3) ALKALINITIES OF WATER
Bicarbonate alkalinity or methyl orange alkalinity was determined by titration of 100 ml. of water sample with N/50 sulphuric acid using methyl orange as an indicator (Welch 1948). The result was expressed in mg. of HCO3 per liter (mg/l) of water.
CALCIUM HARDNESS OF WATER
50 ml of sample pretreated with 1 ml. of 8% sodium hydroxide solution was titrated against EDTA solution (0.01M) using Murexide indicator (Mishra et.al.1992). The result was expressed in mg/l.
MAGNESIUM HARDNESS OF WATER
Magnesium hardness was estimated by following Mishra et.al. (1992)method. The resultant data were expressed in mg/l.
NITRATE-NITROGEN IN WATER
Nitrate-Nitrogen (NO3-N) was estimated by following spectrophotometric method as descried by APHA (1989). The result was expressed in mg/l.
PHOSPHATE CONTENT IN WATER
Orthophosphate was estimated by following Ascorbic Acid Method as described by APHA (1989). The resultant data were expressed in mg/l.
POTASSIUM CONTENT IN WATER
Potassium content was estimated by following Flame Photometric Method as described by APHA (1989). The result was expressed in mg/l.
SODIUM CONTENT IN WATER
Sodium content was estimated by following Flame Photometric Method as described by APHA (1989). The resultant data were expressed in mg/l.
In different seasons soil samples were collected randomly from three different places of the same site. Each sample obtained from two different depths such as top soil (0-18cm) and subsoil (18-36cm) and put into separate polythene bags. The triplicate samples of the same depth of same site were mixed together to make composite sample. So that one sample for each depth was obtained from that site. These soil samples were tagged separately and preserved for soil analysis in the laboratory. Standard methods were followed for soil analysis.
SOIL TEMPERATURE
Centigrade thermometer was used to determination of soil temperature.
HYDROGEN-ION CONCENTRATION (pH) OF SOIL
Soil pH was measured by HANNA digital pH meter (Model HI98107). The ratio of soil to water 1:2.5.
SOIL SALINITY
Soil salinity was measured by portable waterproof Multi-Range Conductivity Meter (Model no Hl9635).
TOTAL NITROGEN OF SOIL
Total Nitrogen was determined by Micro-Kjeldahl’s Method as described by Jackson (1973). The data expressed in percentage (%).
AVAILABLE SOIL PHOSPHORUS
Available soil Phosphorus was extracted with Bray-1 reagent (Bray and Kutz 1945). The Phosphate content of the extract was determined by ascorbic acid blue colour method (Murphy and Riley 1962). The intensity of colour was determined by using Spectrophotometer. The resultant data were expressed in micro gm/g soil.
AVAILABLE SOIL POTASSIUM
Potassium content of soil was determined by Ammonium Acetate Method. The data were expressed in meq/100g soil.
AMMONOUM ACETATE EXTRACTABLE CONTENTS
Neutral 1N NH4OAC (Sehollenberger and Simon 1945) extractable potassium were determined by Flame Photometer and calcium and magnesium were determined by Atomic Absorption Spectrometer. The data of calcium and magnesium were expressed in meq/100g soil.
SOIL ORGANIC CARBON
Soil organic carbon was determined by Walkely and Black’s wet oxidation method as outlined by Jackson (1973). The resultant data were expressed in percentage (%).
SOIL ORGANIC MATTER
Soil organic matter was calculated by multiplying the percent value of organic carbon by the conversion factor of 1.724. The resultant data were expressed in percentage (%).
CATION EXCHANGE CAPACITY (CEC)
Cation exchange capacity of the soil was determined by using neutral 1N NH4OAC solution as described by Black (1965). The data were expressed in meq/100g soil.
Physico-chemical conditions of water such as temperature, salinity, pH, DO, BOD, oxidation reduction potential (Eh), oxidation reduction index (rH2), free CO2, HCO3 alkalinity, calcium hardness, magnesium hardness, nitrogen, phosphate, potassium and sodium contents etc, have been known to be essential for mangrove plant adaptation to particular environment, growth and development. A total fifteen physico-chemical properties have been studied and which results have been mentioned in Table 1,2,3,4,& 5.
WATER TEMPERATURE
Spot 1: During the period of study the temperature of water at this spot varied from 19 to 32.5°C.The maximum temperature was recorded during summer 08 and minimum was recorded during winter 06. The yearly average values 26, 27.8 and 27.6°C were recorded in 2006, 2007 and 2008 respectively. Noticeable fluctuations of temperature have been noted at all study spots during study period.
Spot 2: At this spot water temperature varied from 20 to 31°C. The maximum temperature was recorded during post-monsoon of 2006, and summer of 07 and 08, while the minimum was recorded during winter 06. Similar temperatures were recorded during monsoon of 2007 and 08. The similar yearly average temperature 27.9°C was recorded in 06 and 07, while 28.4°C was recorded in 08. Noticeable fluctuation of temperature has been noted at this spot.
Spot 3: In all the seasons’ water temperature varied from 21 to 32.5°C. The maximum value wasrecorded during monsoon 08 and minimum value was recorded during winter 07. Similar temperature (30°C) was recorded during summer 06, monsoon 06, summer 07 and monsoon 07. The yearly average temperature 26.1, 27.0 and 29.3°C were recorded in 2006, 2007 and 2008 respectively. Noticeable fluctuation of temperature values have been noted at this spot.
Spot 4: During the study period water temperature was found to vary from 20.5 to 33°C. The maximum temperature was recorded during summer 07, and minimum value was recorded during winter 07. The yearly average temperature 28.1, 27.6 and 28.9°C was recorded in 2006, 2007 and 2008 respectively. Noticeable fluctuation of temperature has been noted at this spot.
Spot 3: In all the seasons’ water temperature varied from 21 to 32.5°C. The maximum value wasrecorded during monsoon 08 and minimum value was recorded during winter 07. Similar temperature (30°C) was recorded during summer 06, monsoon 06, summer 07 and monsoon 07. The yearly average temperature 26.1, 27.0 and 29.3°C were recorded in 2006, 2007 and 2008 respectively. Noticeable fluctuation of temperature values have been noted at this spot.
Spot 4: During the study period water temperature was found to vary from 20.5 to 33°C. The maximum temperature was recorded during summer 07, and minimum value was recorded during winter 07. The yearly average temperature 28.1, 27.6 and 28.9°C was recorded in 2006, 2007 and 2008 respectively. Noticeable fluctuation of temperature has been noted at this spot.
Spot 3: At this spot the salinity of water was found to vary from 7.0 to 27.0ppt. Maximum salinity was recorded during summer 06 and the minimum salinity was recorded during winter 07. It was observed that salinity increased gradually from monsoon 06 to monsoon 08. In the period of study the sequence of monsoon salinity values was 9.8 (06) < 11.8 (07) < 12.2 (08). The yearly average salinity values 16.4, 12.9 and 14.4ppt were recorded in 06, 07 and 08 respectively. There were considerable fluctuations in the salinity values have been noted at the spot during the study period.
Spot 4: In all the seasons water salinity ranged between 6.2 to 27.0ppt. Maximum salinity was recorded during summer 06, while the minimum was recorded during post monsoon 07. It was observed that salinity increased gradually from monsoon 06 to monsoon 08. In the period of study the sequence of monsoon salinity values was 10.9 (06) < 11.3 (07) < 12.8 (08). The yearly average salinity values 16.6, 12.2 and 14.8ppt were recorded in 06, 07 and 08 respectively The salinity values were increase and decrease irregularly during the study period.
Spot 5: During the study period salinity of water varied from 7.3 to 25.7ppt. Maximum salinity was recorded during summer 06, and minimum was recorded during post-monsoon 07. It was observed that salinity increased gradually from monsoon 06 to monsoon 08. In the period of study the sequence of monsoon salinity values was 9.8 (06) < 11.8 (07) < 12.5 (08). The yearly average salinity values 16.0, 13.0 and 14.1ppt were recorded in 06, 07 and 08 respectively. Noticeable fluctuation of salinity values have been noted at the spot during study period.The increasing patterns of monsoon salinity at different spots were showed in the figure-1.
Fig. 1. Increasing pattern of monsoon water salinity at different spots from 2006 to 2008.
Spot 1: The pH of water at this spot varied from 7.0 to 7.7. The maximum pH was recorded in summer 07 and minimum was recorded in monsoon 06. The yearly average pH values 7.2, 7.3 and 7.3 were recorded in 06, 07 and 08 respectively. During the period of study more or less uniform data were observed at this spot.
Spot 2: At this spot the pH of water was found to vary from 7.0 to 7.5. Maximum pH value was recorded during summer and monsoon 07, while the minimum value was recorded during post monsoon 06. During the study period the yearly mean pH values 7.2, 7.4 and 7.3 were recorded in the year of 06, 07 and 08 respectively. More or less uniform data were observed at this spot during the study period.
Spot 3: At this spot the range of pH value of water was recorded from 7.0 to 7.6. Maximum pH value was recorded during summer 06 and 07, while minimum pH value was recorded during monsoon, post monsoon 06 and winter 08. The data were more or less uniform at this spot during the study period. The mean values of the year 06, 07 and 08 were recorded 7.3, 7.3 and 7.2 respectively.
Spot 4: During the study period the pH value ranged between7.0 to 8.1. Maximum pH value was recorded during summer 06, and 07, while minimum value was recorded during post monsoon 06. During the study period increasing and decreasing pattern of pH values was irregular. The yearly average values 7.3, 7.3 and 7.6 were recorded in 06, 07 and 08 respectively.
Spot 5: In all the season water pH ranged between7.0 to 7.9. Maximum pH value was recorded during monsoon 08, while the minimum value was recorded during post monsoon 06. The yearly average pH values 7.2, 7.3 and 7.5 were recorded in 06, 07 and 08 respectively. Although seasonal fluctuation did not show a gradual and regular pattern but the yearly average values showed a gradual increasing pattern.
The data are presented in table 1,2,3,4 & 5.
DISSOLVED OXYGEN (DO)
Spot 1: At this spot the dissolved oxygen content varied from 4.1 to 11.5 mg /l. The maximum value was recorded during monsoon 06 and the minimum value was recorded during post monsoon 08. The yearly average data showed that DO content decreasing gradually from 06 to 08. The yearly average values 9.7, 6.1, and 5.3 mg /l were recorded in 06, 07 and 08 respectively. The sequence of decreasing pattern of DO values was 06 > 07> 08.
Spot 2: At this spot DO content of water varied from 4.1 to 12.0 mg/l. The maximum value was recorded during winter 06, while the minimum value was recorded during summer 07. The yearly average values 7.6, 5.6 and 5.2 mg /l were recorded in 06, 97 and 08 respectively. It was observed that DO values were decreasing slowly from the year 06 to 08. The sequence of yearly average DO values was 7.6 (06) > 5.6 (07) > 5.2(08).
Spot 3: In all the seasons DO content of water varied from 4.4 to 12.4 mg /l. The maximum value was recorded during winter 06 and the minimum value was recorded during winter 08. The yearly average values 9.9, 5.8 and 5.4 mg /l were recorded in 06, 07 and 08 respectively. The yearly average data showed that DO values were decreasing slowly form the year 06 to 08. The sequence of yearly average DO values was 9.9 (06) > 5.8 (07) > 5.4 (08).
Spot 4: At this spot DO value varied from 4.2 to 10.8 mg /l. Maximum value was recorded during winter 06, while the minimum value was recorded during summer 07. The yearly average value 7.4, 5.8 and 5.5 mg /l were recorded in 06, 07 and 08 respectively. It was observed that the yearly average DO values were decreasing gradually. The sequence of yearly decreasing pattern of DO values was 06 > 07 > 08.
Spot 5: During the study period DO content of water was found to vary from 4.54 to 13.1 mg /l. The maximum value was recorded during winter 06 and the minimum value was recorded during summer 08. During the study period the yearly average value 10.35, 5.65 and 5.38 mg /l were recorded in 06, 07 and 08 respectively. The yearly average data showed that DO content of water was decreasing slowly. The sequence of yearly decreasing pattern of DO values was 06 > 07 > 08. The decreasing patterns of DO values at different spots were showed in the figure-2.
Fig. 1. Increasing pattern of monsoon water salinity at different spots from 2006 to 2008.
Spot 1: The pH of water at this spot varied from 7.0 to 7.7. The maximum pH was recorded in summer 07 and minimum was recorded in monsoon 06. The yearly average pH values 7.2, 7.3 and 7.3 were recorded in 06, 07 and 08 respectively. During the period of study more or less uniform data were observed at this spot.
Spot 2: At this spot the pH of water was found to vary from 7.0 to 7.5. Maximum pH value was recorded during summer and monsoon 07, while the minimum value was recorded during post monsoon 06. During the study period the yearly mean pH values 7.2, 7.4 and 7.3 were recorded in the year of 06, 07 and 08 respectively. More or less uniform data were observed at this spot during the study period.
Spot 3: At this spot the range of pH value of water was recorded from 7.0 to 7.6. Maximum pH value was recorded during summer 06 and 07, while minimum pH value was recorded during monsoon, post monsoon 06 and winter 08. The data were more or less uniform at this spot during the study period. The mean values of the year 06, 07 and 08 were recorded 7.3, 7.3 and 7.2 respectively.
