Hugli Research Articles

REPRODUCTIVE BIOLOGY OF INDIAN SHAD (TENUALOSA ILISHA) IN THE BHAGIRATHI-HOOGHLY STRETCH OF RIVER GANGA

Hilsa (Tenualosa ilisha ) is a major fishery in the Bhagirathi-Hooghly river accounting for about 15-20% of total fish landings. It is an anadromous fish, which migrates to the Bhagirathi-Hooghly river system from the Bay of Bengal for breeding and spending their earlier part of life. Aspects like gonado-somatic, fecundity, maturity and breeding season were studied during 2011 and 2012. The gonado-somatic relation for male could not be drawn due to highly fluctuating values and for females it was y=8.837+0.004x. Fecundity ranged from 44,002 to 15, 54,894 in the size range of 208mm to 475mm and 105g to 1175.5g. The minimum fecundity value recorded was lowest ever recorded for the species. The first maturity size for males tallied with the previous record but the same was comparatively lower for the females. Breeding season varied with year and indicated linkage with the monsoon and intensity of flood. Key words : Tenualosa ilisha, gonado somatic index, fecundity, maturity, Ganga

Making a river of gold

This article examines the forms of state planning associated with neoliberalism, through a history and ethnography of the Kolkata Port Trust during liberalization. All state plans are promised futures which create a contested dialogue between bureaucrats and citizens. Neoliberal governance makes these interactions particularly ambiguous and opaque, because it relies on decentralized, speculative planning and the stimulation of public-private partnerships. These produce diverse, behind-the-scenes negotiations whose outcome is entirely different from the schemes initially outlined in textual state promises. It also places low-level bureaucrats in a liminal, Janus-faced role, in which they act both to create and to cross a boundary between public and private action. This new mode of rule is particularly problematic in settings such as the Hooghly River, where informality dominates in labor relationships. Bureaucrats deploy practices previously associated with “corruption” and patronage in order to enfold networks of unprotected labor into the revenue streams and plans of the state.

Biogeochemistry of mercury and methylmercury in sediment cores from Sundarban mangrove wetland, India—a UNESCO World Heritage Site

This study was performed to elucidate the distribution, concentration trend and possible sources of total mercury (Hg(T)) and methylmercury (MeHg) in sediment cores (<63 μm particle size; n = 75) of Sundarban mangrove wetland, northeastern part of the Bay of Bengal, India. Total mercury was determined by atomic absorption spectrometry (AAS) in a Leco AMA 254 instrument and MeHg by gas chromatography-atomic fluorescence spectrometry (GC-AFS). A wide range of variation in Hg(T) (0.032-0.196 μg g(-1) dry wt.) as well as MeHg (0.04-0.13 ng g(-1) dry wt.) concentrations revealed a slight local contamination. The prevalent low Hg(T) levels in sediments could be explained by sediment transport by the tidal Hugli (Ganges) River that would dilute the Hg(T) values via sediment mixing processes. A broader variation of MeHg proportions (%) were also observed in samples suggesting that other environmental variables such as organic carbon and microbial activity may play a major role in the methylation process. An overall elevated concentration of Hg(T) in surface layers (0-4 cm) of the core is due to remobilization of mercury from deeper sediments. Based on the index of geoaccumulation (I (geo)) and low effects-range (ER-L) values, it is considered that the sediment is less polluted by Hg(T) and there is less ecotoxicological risk. The paper provides the first information of MeHg in sediments from this wetland environment and the authors strongly recommend further examination of Hg(T) fluxes for the development of a detailed coastal MeHg model. This could provide more refine estimates of a total flux into the water column.

Baseline of butyltin contamination in sediments of Sundarban mangrove wetland and adjacent coastal regions, India

The study reports the first assessment for the quantification and speciation of butyltins (BTs) in surface marine sediment samples (0-5 cm) from intertidal mudflats of Sundarban mangrove wetland along with the Hugli (Ganges) river basin, eastern coastal part of India. Concentrations of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) were monitored at 16 stations and present at all study areas, in concentrations in sediments up to 84.2, 26.4 and 48.0 ng g(-1) of TBT, DBT and MBT, respectively. Significant correlations were obtained between MBT and DBT (r = 0.62, p = 0.01) and DBT and TBT (r = 0.54, p = 0.03). Calculated BT degradation index (BDI) values indicated recent contamination of BTs at 8 stations, and suggested either no degradation of TBT or very recent degradation at a 4 further stations. Additionally, BDI values also indicated no recent inputs of BTs in 4 stations (only MBT present in one of these stations). High concentrations of BTs, particularly TBT, have the potential to induce ecotoxicological impacts based on levels specified in Australian Sediment Quality Guidelines (SQGs). This study indicated that the majority of the analyzed stations were in the highest range of priority, due to high TBT concentrations.

Phytoplankton abundance in relation to cultural eutrophication at the land-ocean boundary of Sunderbans, NE Coast of Bay of Bengal, India

Human activities accelerate the input of plant nutrients sourced from agriculture, industrial waste, and sewage in the Hooghly River at the land ocean boundary of Indian Sunderban mangrove (21°32′–22°40′ N and 88°05′–89° E). This study reports seasonal fluctuations in the phytoplankton assemblage and the relationship between phytoplankton abundance and key environmental parameters in a highly eutrophic system. As far as seasonal perspective, the Hooghly estuarine system dominated by mangrove suffered complete change in terms of phytoplankton and other key parameters during monsoon compared to other times of the year. Diatoms were more abundant than dinoflagellates throughout all seasons with 58 species.

Hydrological changes and their impact on fluvial environment of the lower damodar basin over a period of fifty years of damming The Mighty Damodar River in Eastern India

Abstract The Damodar River is one of the important tributaries of the Bhagirathi – Hugli (Ganges) river system. As the river flows just in opposite direction of rain – bearing monsoon wind, devastating floods were regular occurrences for which the river was famous as the ‘Sorrow of Bengal’. After Independence in 1947, to arrest the catastrophic floods, the Government of India constructed through Damodar Valley Multipurpose Project (DVP), a number of dams, barrage and diversion canals. The main aim of the present study is to trace out the hydrological changes that happened over a period of fifty years of the implementation of DVP on the mighty Damodar River in eastern India. It clearly shows the extent of man induced changes on river regime and their impact on fluvial environment. In the past due to unregulated free flow, the river Damodar opened a number of distributaries e.g. Behula, Kantool, Ghia, Kana Damodar etc. After the construction of four dams and a barrage, because of the massive diversion of upper Damodar water into canals, the lower Damodar is now starved of its natural flow of water. This resulted gradually either de-linking of some of the distributaries from the mother Damodar river and / or a few surviving distributaries turning into kana nadis (blind rivers). This is unique example of how human interference to natural drainage system has changed over the long past the hydrological conditions modifying life drainage into defunct one. Unfortunately, this created just the opposite reaction as instead of controlling floods, the lower Damodar basin is repeatedly devastated by man – made floods. Thus, the Lower Damodar segment shows a dynamic change from a turbulent, frequently overflowing river to now a timid, practically dying channel through human manipulation.

Variations in seasonal phytoplankton assemblages as a response to environmental changes in the surface waters of a hypo saline coastal station along the Bhagirathi–Hooghly estuary

Due to the close proximity of the Bay of Bengal and the freshwater inflow of Bhagirathi-Hooghly, Diamond Harbour appeared as an important coastal station of the Bhagirathi-Hooghly estuary. The spatial and temporal composition and abundance of microphytoplankton species was examined in relation to physical and chemical surface water variables (i.e., salinity, nutrient, and temperature).The primary objective of the study was to observe the variations in phytoplankton species assemblages as a response to environmental variables. Hierarchical cluster analysis and non-metric multidimensional scaling were used to find out distinct seasonal groups based on the composition of phytoplankton. The results indicate that several key environmental factors like temperature, DIN content, and molar ratio of nutrients like DIN-DIP and DIN-DSi influenced seasonal phytoplankton assemblages within the estuary. The distribution of phytoplankton population showed two main groups where the blue-green and green algal populations favored the warmer conditions of summer and monsoon months, whereas the diatom population primarily flourished in the cooler months of autumn and winter.

Level of Heavy Metals in Some Edible Marine Fishes of Mangrove Dominated Tropical Estuarine Areas of Hooghly River, North East Coast of Bay of Bengal, India

The muscles of some important marine fishes collected in and around Hooghly estuarine coastal areas were analyzed for the heavy metals Cu, Zn, Ni, Cd, Cr and Pb. The concentration range of Cu (16.22-47.97 ppm), Pb (12.40-19.96 ppm) and Zn (12.13-44.74 ppm) were recorded comparatively higher and were similar to that found in contaminated areas. On the other hand the ranges of Ni (2.20-3.69 ppm), Cr (0-3.89 ppm) and Cd (0.62-1.20 ppm) were almost equal to those carried out over a wide range of geographical areas. The degree of bioaccumulations was metal-specific as well as species-specific in nature. The toxic groups of metals (Pb and Cd) showed higher variability than the essential metals (Cu, Zn and Ni). The calculated intake value of metals (week⁻¹ kg⁻¹ body wt) varied from 14.88 to 27.60 of Pb, 0.87 to 1.68 of Cd, 0.0 to 5.45 of Cr, 22.70 to 137.16 of Cu, 3.08 to 5.17 of Ni and 16.98 to 62.60 of Zn through human consumption of these fishes and were compared with those of standard Provisional Tolerable Weekly Intake value (PTWI) per kg body weight as stipulated by WHO. The PTWI(Cal) values of Pb in some of the fishes recorded marginally excess values and may indicate a health risk through consumption of successive 7 days in a week.

Acid leachable trace metals in sediment cores from Sunderban Mangrove Wetland, India: an approach towards regular monitoring

The paper presents the first document to identify the enrichment pattern of acid leachable trace metals (ALTMs) such as Fe, Mn, Cr, Cu, Ni, Pb, Cd, Co, Mo, Ag, As and Ba and their relationship with sediment quality parameters (pH, organic carbon, carbonates and texture) in core sediments (<63 microm particle size) from Indian Sunderban mangrove wetland, formed at the estuarine phase of the river Hugli (Ganges). Textural analysis reveals an overall predominance of mud. The results indicate that the change in pH values causes coagulation and precipitation of ALTMs. Fe and Mn have fairly close distribution patterns of enrichment in surface layers which might be ascribed to early diagnetic processes. The most prominent feature of ALTMs is the enrichment of Fe, Mn, Cr, Cu, Ni, Pb, and Ba in the surface-subsurface layers in the sediment cores, which is mainly attributed to the intense industrial and agricultural activities as well as drainage of untreated domestic sewage to this coastal region. The ALTMs also indicate their association with organic carbon and Fe-Mn oxyhydroxides. The enrichment is well--supported by the correlation, grouping and clustering of ALTMs in statistical analyses. Anthropogenic Factor values indicated ALTMs enrichment for all trace metals due to intense anthropogenic activities. Overall higher values of ALTMs in sediments in comparison to other Indian coastal regions indicate that they are mainly due to the uncontrolled anthropogenic activities in this mangrove estuarine complex. Statistical analyses suggest that five ALTMs (Cu, Pb, As, Mo, Ba) are attached to the organic particles and the clustering of elements separately also indicates that they are from external source. The result of the present study suggests the need for a regular monitoring program which will help to improve the quality of this potential wetland.

Synthetic Detergents (Surfactants) and Organochlorine Pesticide Signatures in Surface Water and Groundwater of Greater Kolkata, India

An assessment on the concentration of surfactants and pesticides of chlorinated hydrocarbon group in surface and groundwater, is made from Greater Kolkata located in the Western Ganga Delta, one of the largest urban agglomerate in Asia. Concentration of both anionic synthetic detergents and organochlorine pesticide resi-dues analysed from 54 and 19 sampling stations covering groundwater and surface water sources respec-tively, are generally found to be within the tolerance limit for human consumption. The concentration of synthetic detergent ranges from 0.084 to 0.425mg/l. Residues of organochlorine pesticides are analysed from different sources like tanks, lakes, rivers and groundwater. Lindane (0.01-0.43µg/l) and DDT (0.03-0.65 µg/l) are the most widely detected pesticide residues. Howerer, the two have not exceeded the limits for drinking anywhere. High value of aldrin and dieldrin (0.9µg/l) is obtained in the river Hugli at Barakpur-Seoraphuli, 20 km north of Kolkata. Likewise high value of Heptachloreis detected in a canal water sample at Palta (0.05 µg/l), a suburban area. Seasonally, the pesticide concentration in surface water is maximum during winter due to their higher application and minimum during monsoon. In groundwater, however, this relationship is reverse due to higher infiltration of surface water during monsoon.

Freshwater fish habitat science and management in India

India is a land of diverse topography, climate and natural resource. There are 12 major rivers and 48 lesser rivers with a total catchment area of 277.6 million ha. The freshwater resources of the country, which are varied, harbor 587 species of finfishes, and account for 9.3 percent of global inland fish production. India's natural capital of fish habitat resource has been eroded as reflected in loss of biodiversity and reduced fish landings. Studies on the ecology, environment and fisheries of five major river systems, in addition to reservoirs and flood plain lake fisheries, have been conducted with greater focus on water quality and less on physical habitat parameters. River conservation programs cover major rivers in 10 states of the country; the ‘Ganga Action Plan’ being the most important. These projects target improvement in water quality and not fish habitat. Lack of concern for fish habitat is reflected in the planning of Farakka Barrage, a large dam built to divert the flow of River Ganga (The Ganges) into the Hooghly River, and its impact on the ‘Hilsa’ run. Environmental laws have not achieved desired results for lack of enforcement mechanisms. Freshwater habitat management in India raises both concern and hope. Concern arises out of the missing elements in current fish habitat research, planning and management of resource. The hope for the future is increasing public awareness on the need for better resource management and environmental conservation. In the backdrop of the learning from implementation of the eco-restoration programmes, the task appears to be not only challenging but also demanding in terms of participation of stakeholders, commitment of resources, backup of research support, monitoring of environmental standards, enforcement of regulations and setting up of priorities in terms of conservation of the natural assets.

An Assessment of Mercury Loading in Core Sediments of Sunderban Mangrove Wetland, India (A Preliminary Report)

This is a preliminary report on total mercury (T(Hg)) in core sediments (<63 microm particle size) of Sunderban mangrove wetland, northeastern part of the Bay of Bengal, India. Cold vapor atomic absorption spectrometry (CVAAS) was used for T(Hg) determination. The concentration varies from 9.8 to 535.1 ppb (ngg(-1)). Results revealed variations over premonsoon and postmonsoon month at different core depth, as well as in studied three sampling stations, located at the site of three rivers: Hugli River (S(1)), Matla River (S(2)) and Bidyadhari River (S(3)). Elevated concentration of T(Hg) in subsurface layer (4-8 cm) of the core at S(2) is attributed to remobilization of mercury from deeper sediment (32-36 cm). Positive correlation is present between total Hg and clay content. Based on index of geoaccumulation (I(geo)) and Effects-Range Low (ER-L) value (150 ppb) it is considered that the sediments are till now unpolluted. As a consequence, there is less chance of ecotoxicological risk to organisms living in studied sediments. Two statistical methods were applied to determine T(Hg) anomalies. Box plot method showed one extreme and three outliers in S(1) at postmonsoon season. Two extremes were found at S(2) at 4-8 and at 32-36 cm in premonsoon period. In S(3) there was no anomaly by box plot method. MAD method was more sensitive than box plot method and T(Hg) anomaly was detected at 12-16 cm in S(3) during postmonsoon season. The data reported are useful baselines for T(Hg) in Sunderban mangrove wetland, India and would be of help in future sediment quality studies.

Finite Volume Model for Shallow Water Equations with Improved Treatment of Source Terms

A simple yet precise relation between the flux gradient and the bed slope source term is presented, which produces a net force within the cell with an inclined water surface, but ensures still water condition when there is no flow across the boundaries. The proposed method consists of calculating the pressure term based on the water depths at the cell vertices, which may be computed by a higher order scheme and the bed slope source term by a centered discretization technique. The methodology is demonstrated with a Godunov-type upwind finite volume formulation. The inviscid fluxes are calculated using Roe’s approximate Riemann solver and a second-order spatial accuracy is obtained by implementing multidimensional gradient reconstruction and slope limiting techniques. The accuracy and applicability of the numerical model is verified with a couple of test problems and a real flow example of tidal water movement in a stretch of River Hooghly in India.

Comparison of dissolved and particulate arsenic distributions in shallow aquifers of Chakdaha, India, and Araihazar, Bangladesh

BackgroundThe origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh.ResultsVariations in surface geomorphology mapped by electromagnetic conductivity indicate that permeable sandy soils are associated with underlying aquifers that are moderately reducing to a depth of 10–30 m, as indicated by acid-leachable Fe(II)/Fe ratios <0.6 in the solid phase and concentrations of dissolved sulfate >5 mg L-1. More reducing aquifers are typically capped with finer-grained soils. The patterns suggest that vertical recharge through permeable soils is associated with a flux of oxidants on the banks of the Hooghly River and, further inland, in both Chakdaha and Araihazar. Moderately reducing conditions maintained by local recharge are generally associated with low As concentrations in Araihazar, but not systematically so in Chakdaha. Unlike Araihazar, there is also little correspondence in Chakdaha between dissolved As concentrations in groundwater and the P-extractable As content of aquifer particles, averaging 191 ± 122 ug As/L, 1.1 ± 1.5 mg As kg-1 (n = 43) and 108 ± 31 ug As/L, 3.1 ± 6.5 mg As kg-1 (n = 60), respectively. We tentatively attribute these differences to a combination of younger floodplain sediments, and therefore possibly more than one mechanism of As release, as well as less reducing conditions in Chakdaha compared to Araihazar.ConclusionSystematic dating of groundwater and sediment, combined with detailed mapping of the composition of aquifer solids and groundwater, will be needed to identify the various mechanisms underlying the complex distribution of As in aquifers of the Bengal Basin.

Hydrochemical framework of the aquifer in and around East Kolkata Wetlands, West Bengal, India

The area lies between Hugli river in the northwest and Bidyadhari river in the east and includes the East Kolkata Wetlands. The East Kolkata Wetlands is included in the List of Wetlands of International Importance (“Ramsar List”), as per the Convention on Wetlands signed in Ramsar, Iran, in 1971. This wetland has been declared as a Ramsar site on the 19th August 2002 (Ramsar site no. 1208) and therefore has acquired an international status. The area is a part of the lower deltaic plain of the Bhagirathi–Ganga river system and is generally flat in nature. The sub-surface geology of the area is completely blanketed by the Quaternary fluviatile sediments comprising a succession of clay, silty clay, sand and sand mixed with occasional gravel. The Quaternary aquifer is sandwiched between two clay sequences. The confined aquifer is made up of moderately well sorted sand and reflects fluviatile environment of deposition. The regional groundwater flow direction is from east to west. Detailed geochemical investigations of 40 groundwater samples along with statistical analysis (for example, correlation and principal component analysis) on these chemical data reveal: (i) four types of groundwater quality, for example, good, poor, very poor and water unsuitable for drinking purpose, (ii) four hydrochemical facies which may be assigned to three broad types such as “fresh”, “blended”, and “brackish” waters, (iii) the evolution of the “blended” water is possibly due to hydraulic mixing of “fresh” and “brackish” waters within the aquifer matrix and/or in well mixing, and (iv) absence of Na–Cl facies indicates continuous flushing of the aquifer.

‘Dispersal’ and the Failure of Rehabilitation: Refugee Camp-dwellers and Squatters in West Bengal

In September 1950, the Government of West Bengal dispatched 500 Hindu refugee families to the village of Jirat in Hooghly district. It intended to build a camp there permanently to house these refugees, who had fled from East Bengal in the turbulent aftermath of the partition of India. Some forty miles from Calcutta, Jirat was situated on the west bank of the River Hooghly. It had once been a substantial and prosperous village, significant enough to earn a mention in Rennell's Atlas of 1786, where wealthy people built large homes and temples. Indeed the ancestral home of Dr Syama Prasad Mookerjee—educationist and politician, founder of the Hindu nationalist Jana Sangh party, and ironically, one of the most vociferous champions of the Hindu refugees in Bengal after partition—was situated in the village. In the 19th century, however, the river had changed its course and Jirat's population was ravaged by a particularly virulent strain of the dreaded ‘Burdwan fever’. By 1950, when the refugees arrived at Jirat, the village had long since been abandoned, its waterways choked with silt, its ponds filthy and overgrown with water hyacinth, its great buildings crumbling and derelict. A rare ‘empty’ corner in crowded West Bengal, the Government of West Bengal deemed it to be an appropriate place to house and rehabilitate two and a half thousand refugees: men, women and children.

Chemodynamics of an arsenic “hotspot” in a West Bengal aquifer: A field and reactive transport modeling study

Extremely high As concentrations in drinking water of the Ganges Delta (West Bengal and Bangladesh) has emerged as an issue of great concern in the past decade because of its serious impact on the health of millions of people. The distribution pattern of As concentrations in the Ganges Delta region is patchy and there are numerous As “hotspots”. The present study is perhaps the first attempt in West Bengal to characterize such a hotspot by geophysical and geochemical methods, and to model the transport of the enrichment plume using a 1D reactive transport model (PHREEQC). The study site is located along the Hooghly River, 60 km north of Kolkota City, near the city of Chakdaha. Total As concentrations in the groundwater range from 0.5 to more than 6 μmol L −1; the WHO recommended maximum drinking water concentration is 0.13 μmol L −1 (i.e. 10 μg L −1). Results show groundwater is in chemical equilibrium with siderite and calcite, a mineral phase previously shown to be an efficient trap for As(III). Groundwater redox potential is controlled by the Fe(OH) 3(am)/Fe 2+ couple. The As(III) versus As(V) distribution (42% As(III) and 58% As(V), on average) is not at equilibrium with measured Eh values. No evidence of sulfide solid phases, such as As rich pyrite or arsenopyrite, was found. Although amorphous Fe dissolution is confirmed to play an important role in the release of As, selective dissolution extractions indicate that adsorption of As on carbonates and micas may also be an important component of As cycling in the sediment. Modelling results demonstrate the role of PO 4 3 - , HCO 3 - and Fe(II) in mobilizing the As plume, thereby increasing the threat to the 75,000 inhabitants of Chakdaha.

Water quality management in the lower stretch of the river Ganges, east coast of India: an approach through environmental education

The lower tidal stretch of the river Ganges, known as Hugli (ca. 280 km), flows southward before entering the Bay of Bengal forming a vast mangrove-enriched estuarine delta called Sunderbans. Hugli estuary is a typical example of tide-dominated sink for contaminants from multifarious sources. This major important river is subjected to anthropogenic stress due to the socio-economic importance of these areas based on growth of industry, agriculture, aquaculture, port activities, fishing and tourism. The living resources have been degraded recently due to increases in population pressure, pollution and natural resource consumption to the extent of overexploitation. The present paper critically examines the physicochemical characteristics and level of dissolved heavy metals at three ecologically distinct zones along the course of the river – Babughat located in the eastern part of the metropolitan megacity Calcutta (140 km upstream from seaface), Diamond Harbor (70 km upstream from sea face) and Gangasagar positioned at the mouth of the Ganges estuary. Physicochemical characteristics of this partially mixed estuary are largely influenced by the interaction of seawater and discharge of riverine freshwater, annual precipitation and surface runoff. The levels of salinity, total dissolved solids, hardness and conductivity showed an increasing downward trend. Marked increase in biochemical oxygen demand (BOD) values (2.20–5.95 mg/l) was recorded in Babughat whereas correspondingly low values (0.75–2.82 mg/l) were noticed at Gangasagar. This can be attributed mainly due to huge organic load of untreated sewage from the twin city Howrah and Calcutta situated in the east and west of the river. Spatiotemporal distribution of heavy metals reveals a wide range of variations reflecting input of huge anthropogenic inputs associated with a number of physical and chemical processes. Levels of metals registered a seasonal pattern, with an increase during late monsoon months (September–October), a period characterized by low salinity and relatively low pH of the water. Elevated levels of dissolved Hg and Pb were also recorded in Babughat, with values ranging from 0.16 to 0.95 μg/ml and 0.017 to 0.076 μg/ml, respectively, this high values for Hg can be attributed to the discharge from pulp and paper manufacturing units and to atmospheric input and runoff of automobile emission for Pb. It was revealed that the socio-economic development of Calcutta, the most potential economic zone in India situated on the east bank of Hugli river, has had a significant impact on the water quality of this major river. The deterioration of water quality is directly related to nonfunctioning and malfunctioning of wastewater treatment plants and lack of environmental planning and coordination. To restore the ecological stability and economic vitality of this river, the following measures have been suggested: (i) strong vigilance programme is to be undertaken towards installation and maintenance of the wastewater treatment plants to check the flow of persistent contaminants in the river water and (ii) execution of legislation and mass awareness programmes are to be enacted to restore the sound health of the river. The authors urge that environmental education should be used as an effective tool for water resource management dealing with intricate and complex problems in the interaction between nature, technology and human beings.

Fluxes of nutrients from the tropical River Hooghly at the land–ocean boundary of Sundarbans, NE Coast of Bay of Bengal, India

The Ganges drains much of the southern slopes of the Himalayas and yields high-suspended sediment load during the monsoon. The Hooghly estuary, the first deltaic offshoot of the Ganges and flows through the western part of the Sundarbans mangrove forest is a source for inorganic nutrients due to the high input of litter and sediment associated nutrients that are released during estuarine transport. Dissolved inorganic carbon (DIC), dissolved inorganic nitrogen (DIN), dissolved reactive phosphate (DRP) and silicate budgets and fluxes of the coastal zone of the Hooghly River system have been done by biogeochemical modeling and their annual fluxes were calculated to be 230 × 10 9 mol (2.76 × 10 6 t), 4705 × 10 6 mol (65.8 × 10 3 t), 415 × 10 6 mol (12.8 × 10 3 t), 15.28 × 10 9 mol (42.8 × 10 3 t), respectively. Out of the total transport, monsoonal runoff could account 64% for DIC, 71% for DIN and 76% for both DRP and silicate. Annual load of sediment out of the estuary to the NE coast of Bay of Bengal was estimated to be 65.19 × 10 6 t. During the estuarine transport 7.5% of DIC and 7.0% of silicate were removed while addition for DIN and DRP were found to be 59% and 44%, respectively. Occurrence of light limited conditions and auto-heterotrophic coupling within the estuary results regeneration of nutrients from organic matter originated from external source. Comparison was made with the estimates of nutrient fluxes through the some mangrove dominated Southeast Asian estuaries.

Diversity and Distribution of Arthropod Fauna in Relation to Mangrove Vegetation on a Newly Emerged Island on the River Hooghly, West Bengal

Diversity and Distribution of Arthropod Fauna in Relation to Mangrove Vegetation on a Newly Emerged Island on the River Hooghly, West Bengal