Studies on Sediment Physico-Chemical Properties of the Ulhas River flowing along Dombivli City near Mumbai

. Ulhas River which is one of the most polluted rivers of Mumbai receives heavy pollution load from the nearby Dombivali industrial belt. Previous studies reported along the Dombivali industrial belt has indicated that the pollution level is so much alarming that it has created threat to nearby residential areas and also to the Ulhas River flowing in the outskirts of the Dombivali City. It is feared that the toxic chemicals present in the industrial waste might affect the sediment ecosystem of the river. Hence this has provoked us to carry the systematic and detailed study of physico chemical properties of the sediment samples collected along the Ulhas River. The study was done during the year 2012 and 2013, at the sites where the industrial discharge from Dombivli industrial belt Phase I and Phase II joins the Ulhas River. The study was performed to understand the physico chemical properties such as pH, alkalinity, chloride and phosphates. Results of the study reveal that there is an urgent requirement for systematic and regular monitoring of pollution level along the Ulhas River which will further help in improving the industrial waste treatment procedure adopted, along the Dombivli industrial belt. It is expected that such scientific studies will be useful to determine the extent of pollution control measures required in order to avoid long term irreparable damage to the Ulhas River ecosystem.


INTRODUCTION
India has undergone the phase of revolution in the industrial sector. Subsequently, the waste generation and discharge from these industries has also increased. However, this quantum of growth is not proportional to the increase in number of waste treatment facilities and the stringiness of pollution control measures followed by the industries. The reason being, there are many small scale industries, which may compromise the requirements for treatment of generated wastes, since they do not afford huge investment for pollution control facility due to very thin profit margin. Though major industries have waste treatment facilities, the overall effect is that the water of Ulhas river is polluted due to the discharge of industrial waste. This has resulted to increase in pollution of air, water and sediment. The quality of water and sediments is significantly impacted. In most of the stretches, it is found that almost all rivers are polluted by some industry or the other [1]. All industries in India are bound to adhere to the strict guidelines of the Central Pollution Control Board (CPCB), but still the environmental situation is far from control. There are sufficient evidences in India available, related to the mismanagement of industrial wastes [2][3][4][5][6][7]. The physico chemical properties of sediments are affected by the untreated waste. Sediments act as a natural buffer and filter system in the material cycles of water and the sediment quality, quantity or both have an impact on the ecological quality [8]. Sediments are the important habitat and serve as a main nutrient source for organisms in aquatic life. Bacteria inhabit the sediments. Organic matter is decomposed with the help of these bacteria. The aquatic productivity is also impacted due to the metabolic activity of benthic macro invertebrates which are present in the sediments. There is an interchange of important macronutrients going on continuously between the sediments and overlying water [9]. Toxic effect on sediment dwelling organisms and fishes are observed, due to accumulation of pollutants over a long period, as a result of biological and geochemical mechanisms. This results to decrease in the chances of survival, reduction in growth, impaired reproduction and decreased diversity of species [10,11]. Important information related to the long term quality situation can be obtained from sediment testing and is independent of current inputs as compared to water testing [12,13]. Other influences minimally affect or do not affect the sediment testing. Water testing does not help to clearly differentiate between true and temporary suspension substances, stirred up from the sediments. Sediments act as a sink and source of contaminants in aquatic systems. Sediments will help to speculate sources of contamination. Pollutants remain in the sediments over long periods of time, depending on the chemical persistence, the physical-chemical and biochemical characteristics of the substrata. The suspended and precipitated substances eventually settle down at the bottom and serve as a reservoir for trace substances of low solubility, low degree of degradability and many pollutants [14 -16]. Information related to natural and anthropogenic influence on the water bodies, which is environmentally significant, can be obtained from the chemical analysis for characterization of sediments [17][18][19][20][21][22]. Thus, to evaluate the quality of total ecosystem of a water body, in addition to the water sample analysis, the analysis of sediment is of equal importance [23 -31]. The Ulhas River is one of the important water bodies in Thane District in the state of Maharashtra. It flows along the Dombivli city near Mumbai, during its journey to the sea. There are two industrial phases in Dombivli MIDC (Maharashtra Industrial Development Corporation) zones, namely Phase I and Phase II. At two different locations along the Ulhas River, the effluents from these two phases are discharged into the Ulhas River. It is known that the Ulhas River is heavily polluted due to discharge of toxic pollutants and solid wastes from the industries and localities situated along Dombivli, Ulhas Nagar, Bhiwandi, Ambivli and Thane City based on the previous research [32 -34]. Thus it is expected that this reservoir can serve as a model for studying the physico chemical properties of sediments. Systematic and periodic monitoring is very essential to assess the extent and severity of sediment contamination to evaluate the effects of contaminated sediments on marine environment and fresh water. We therefore initiated such a study to understand the Physico Chemical Properties of the sediment of Ulhas River along the Dombivli city situated near Mumbai, India. The study was performed to understand the physico-chemical parameters like pH, alkalinity, chloride, phosphate, cyanide and fluoride. The results will help in understanding the effectiveness of pollution control measures already is existence; extent of pollution control needed; rational planning of pollution control strategies and their prioritization.

Area of study
The study was carried out along the banks of Ulhas River where the effluents released from industries of Dombivli MIDC (Maharashtra Industrial Development Corporation) Industrial belt Phase I and Phase II are discharged. In 1964, Dombivli industrial area was established by Maharashtra Industrial Development Corporation. The industrial belt is located in south of Ulhas River and covers an area of about 347.88 hector. Many small / medium / large scale fine chemicals, dyes manufacturing, agrochemicals, textile, pharmaceutical, engineering, metallurgical and paint manufacturing industries are located in this industrial belt which contribute heavy pollution in the surrounding area [35][36][37][38][39][40][41][42][43]. The industrial effluent generated from the industrial area is about 14 MLD which is regularly discharged through open drainages into the nearby flowing Ulhas River [44]. Following suitable location/s for sampling of sediments were identified: Sampling Point S1: Before the discharge of effluent (D1) from Dombivli MIDC Phase I. Sampling Point S2: After the discharge of effluent from (D1) Dombivli MIDC Phase 1. Sampling Point S3: After the discharge of effluent from (D2) Dombivli MIDC Phase II. Sampling Point S4: After the discharge of effluent from (D2) Dombivli MIDC Phase II.

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ILCPA Volume 52 The sampling locations are as shown in (Figure 1).

Figure1
: Effluent discharge and sampling locations in Ulhas River along Dombivli City.

Climatic conditions
Dombivli enjoys a tropical climate with mean annual temperature of about 24.3 o C to 32.9 o C. The hottest and most dry part of the year is April and May and the temperature rises to 38.0 o C. Humidity present in the atmosphere is usually 58 to 84% and sea breeze in the evening hours is a blessing to combat the high temperature and humidity during summer months. The average southwest monsoon rainfall is in the range of 1850 mm to 2000 mm. The average annual rainfall in the region is the range from 1286 to 1233 mm [44].

Sample planning, collection and preservation
The study on pollution status along the Ulhas River was carried out in year 2012 and 2013. Sediment sampling was done every week along identified locations of the Ulhas River along Dombivli city area. The samples collected for four months were mixed separately to give gross sample of one season. This was followed for all the three seasons -summer, rainy and winter for a period of twenty four months. The samples were collected by hand-pushing plastic core tubes (7 cm diameter) as far as possible into the sediment. Sediment samples were thoroughly mixed, placed in polythene bags and kept in a dry place until analyses. The samples were the air dried and ground using agate mortar. The samples were further sieved with 0.5 mm mesh size sieve to remove stones, plant roots and to obtain sediment of uniform particle size. These sediment samples were then thoroughly mixed and packed in polythene bags.

Quality Assurance
To avoid any contamination, plastic-made implements were used for sampling and collection of sediment samples. Polythene bags were used to store the sediment samples. To avoid contamination from the environment during their transport from sampling locations to the laboratory, they were well covered. To avoid any cross contamination during grinding, tools and work surfaces were carefully cleaned. The relevant laboratory apparatus were soaked in nitric acid before analysis followed by rinsing thoroughly with tap water followed by deionised distilled water, to ensure that all traces of cleaning reagents are removed. The glassware used in the analysis was washed with distilled de-ionised water. All calibrated instruments were used for analysis. Reagents were standardized with primary standards to determine their actual concentrations. Analytical grade chemicals and reagents were used for analysis.
International Letters of Chemistry, Physics and Astronomy Vol. 52 13

Physico-chemical Study
The present study provides a detailed description of the physico-chemical properties of sediment samples, collected at four different locations from the Ulhas River along the Dombivli City, near the discharge of effluents from the industrial belt of Dombivli. The physico-chemical parameters studied were pH, alkalinity, phosphate and chloride. For physical and chemical analysis of sediment samples, standard techniques and methods were followed [45,46]. Average value of three replicates was taken for each determination.

RESULTS AND DISCUSSION
The sediment samples collected at various sampling points from the Ulhas River flowing along the Dombivli city near Mumbai in year 2012 and 2013 where analyzed for their Physico Chemical properties. The average analytical results are presented in Table 1. The average values of pH of sediment at different sampling points for year 2012 and 2013 are shown in Table 1 and the variation is represented in Figure 2.
14 ILCPA Volume 52  Table 1 and the variation is represented in Figure 3.  Table 1 and the variation is represented in Figure 4.  Table 1 and the variation is represented in Figure 5.
International Letters of Chemistry, Physics and Astronomy Vol. 52 Phosphorus pollution causes eutrophication. The process of a river's biological death due to depleted bioavailable oxygen is termed as eutrophication. Excess phosphorus causes algal blooms. The blooms favour the survival of less desirable fish over more desirable commercial and recreation species, thus impacting fisheries. Phosphorus pollution caused enormous blooms of the Blue-Green Algae which is a form of cyanobacteria. These bacteria produce toxins that damage water quality, aquatic ecosystems and fisheries. Excess phosphorus and nitrogen helps the rapid growth of Phytoplankton, creating dense populations or blooms. Such dense blooms limit the amount of sunlight available to submerged aquatic vegetation. Thus the plants cannot photo-synthesize which is essential for survival. Absence of sunlight can kill aquatic grasses. Phosphate pollutants settle and get accumulated in bottom sediments from where they may be released back to the surface water under certain conditions. This which will subsequently increase the concentration of dissolved phosphates (as phosphorous) above the permissible limit of 5.0 mg/L Max, set for inland surface water [49].

CONCLUSIONS
There is a significant increase in the generation and discharge of industrial waste due to the rapid industrialization, along the Dombivli industrial belt. These effluent wastes are discharged into the Ulhas River flowing along the Dombivili City near Mumbai. There are many small scale industries, which may compromise the requirements for the treatment of effluent wastes, since they do not afford high investment for pollution control facility as they have very thin profit margin. Though major industries have waste treatment facilities, the overall effect is that the water of Ulhas river is polluted. Sufficient evidences related to the mismanagement of industrial wastes are available which demonstrates the same situation. The present experimental data highlights the  42 ppm in year 2013. The positive observation is that cyanide and fluoride is not detected in the river sediments. Overall it can be concluded that the pollution has increased in year 2013 as compared to that in year 2012. It is also observed that the pollution has increased after the discharge of industrial effluents into the Ulhas River along Dombivli city. It can be concluded that there is a need of further systematic and regular monitoring of pollution level along the Ulhas River which will further help in improving the industrial waste treatment procedure adopted, along the Dombivli industrial belt. The present data on physico chemical properties of the sediments of Ulhas River along the Dombivli city will help in rational planning of pollution control strategies and their prioritization; to assess the nature and extent of pollution control needed; to evaluate effectiveness of pollution control measures already in existence. It will also help to provide a means for evaluating the long term accumulation contaminants in the sediment ecosystem of the Ulhas River.