Abstracts of International Workshop on Environmental Biogeochemistry
Simulation of the Indian summer monsoon in the land-ocean atmosphere system of a coupled GCM
A 150 year-long numerical simulation of present-day climate using the Max-Planck Institute s coupled ocean-atmosphere model ECHAM4 -T42-OPYSC3 is analysed with regard to the interannual variability of the strength of the Indian summer monsoon and its relation to land-surface and ocean interactions. Individual years are categorised into three classes of monsoons: normal, strong and weak (greater or less than one standard deviation of precipitation over India). Theens embles of anomalous monsoons are then sub-deviation of precipitation over India). Theens embles of anomalous monsoons are then sub-divided into a composite of cases coinciding with sea surface temperature (SST) anomalies in the Pacific related to the El Ni= F1o-Southern Oscillation (ENSO) phenomenon and a second composite of anomalous monsoons occurring when no SST anomalies are found in the Pacific. The coupled model shows variations of the SST in the Pacific which are as large as and occur at a similar frequency as in observations. Thus it provides the basis for arealistic simulation of the interannual monsoon variability in ENSO- related conditions.
Analysis of sediment data from morel than 500 global rivers shows two quite different trends, depending on whether one considers solid or dissolved sediment. The geomorphic/tectonic character of the drainage basin and the basin area have first-order controls on the solid sediment (SS) discharge of most rivers. Toporgraphic control also served as a surrogate for tectonic character of the basin, which in turn such things as eearthquakes, landslides and - to some extent- the geological character of the rocks themselves. Younger rocks are generally more easily eroded than older rocks; and sedimentary rocks more erodable than metamorphic rocks. Climate (particularly precipitation) and human impact also play important roles, often explaining deviations from the load predicted on the basis of topography and basin are alone. Many of the present-day smaller mountainous rivers discharge onto active margins with narrow shelves. As such, there is often little chance for sediment storage on land and relatively little chance for sediment to accumulate on the shelf. Most of the sediment presumably escapes to the slope and the deep sea beyond. As such, smaller mountainous rivers can serve as modern analogs of conditions as they existed during lower stands of sea level. There also is some evidence (although still controversial), for example, that rivers discharging eastwards from New Guinea may be responsible for the anomalously high particulate aluminium and iron contents found in the Equatorial Counter Current, which in turn may fertilize the high productivity in the eastern equatorial Pacific. If true, this would suggest that fluvial imprints on the global ocean may be far greater and wider ranging than commonly believed.
Information is a resource, which together with physical, economical, technical and human resource is a must for national development. Sustainable development, which has evolved as the goal for human welfare in recent times, is rooted in the availability of right information to the right person at the right place and at the right time. The need for information arises at all levels, from that of senior decision-makers, at the national and international levels to the grass roots and individual levels. Environmentally sound decisions, which are a must for achieving sustainable development, are not possible in an information vacuum.
Environmental information is, therefore, of vital importance. Realising the importance of environmental information, an Environmental Information System (ENVIS) has been established by the Ministry of Environment and Forests in 1982 to provide information to decision-makers, policy- planners, scientists, etc. all over the country. Dissemination of information to the users is the most vital component in the whole system for providing the users satisfaction. ENVIS is a decentralised network information system consisting of Focal Point in the Ministry coordinating the activities of a chain of 24 subject specific centres, known as ENVIS Centres located in various prestigious institutions/organisations all over the country. The purpose of the ENVIS Centre is to cater to the needs of the people do not have access to highly equipped libraries and network systems. ENVIS Centre is building up a good collection of books, reports and journals in the particular subject area of environment. Establishment of linkages with all information sources in the particular subject of environment. Repsonding to users queries. Establishment of a data Bank on some selected parameters relating to the subject area. Identification of gaps in the subject area and action to fill these gaps.Bringing out newsletter/publications in the subject area for wide dissemination.
There are several potential climate feedback that could affect the atmospheric and the budget. Traditionally, temperature increases are assumed to generate increases in CH4 emissions. Recent calculations suggest a moderate increase in CH4 emissions in a 2 X CO2 scenario (Harriss et al., 1993). Methane is the only long- lived gas that has clearly identified chemical feedback: increases in atmosphertic CH4 reduce the concentration of tropospheric OH articles, increase the CH4 lifetime and and hence amplify the original CH4 perturbation. The chemical feedbacks of CH4 on OH chemistry results in the reduction of CH4 removal rate ranging from - 0.17% to -0.35% for each 1% increase in CH4 concentration. Also predicted increases in tropospheric O3 varied by a factor of three or more averaging about 1.5 ppbv throughout most of the troposphere in both tropics and summertime mid latitudes. Based on our existing knowledge on the importance of CH4 to the tropospheric chemistry, and its chemical feedback, extensive studies on quantifying and refining the source data base was our primary objective. This paper discusses the importance of CH4 as a greenhouse gas, its cycling in rice paddy and in wetlands and its implication to the threat of global warming.
(1) Laboratoire de Geochimie, OMP-UMR-CNRS 5563, 38 rue des 36 ponts, 31400 Toulouse
(2) ORSTOM TOA, BP 1857, Yaounde, Cameroun
We have recently works on the chemical composition of the rivers flowing in tropical region. We have shown that these rivers shown very peculiar characteristics. High amount of COD, Al and Fe, low concentration of major elements. We have interpreted these characeteristics by the effect of organic matter on chemical weathering we have made chemical studies on a representative small watershed. We describe below the main results we have obtained on this watershed (Nsimi/Zoetele, South Cameroon). The Nsimi basin is a pilot site of the PEGI program (programme d Environment de la Geosphere Intertropicale, ORSTOM-CNRS) and it offers a unique opportunity to study weathering mechanisms in a lateritic system within a small basin by coupling soil and water chemistry. The lateritic cover in this site can reach upto 40 m in depth and show two pedological distinct zones: 1) slope soils on the hills or elevated areas nad2) hydromorphic soils in the swamp zone which represent 20% of the basin surface. The first results obtained from this program show strong chemical differences between waters located in slope zones (depleted inn organic matter) and those pounded in swamp zones (enriched in organic matter). The study was performed on waters samples taken from piezometric wells and springs in slope areas, and from peezometric wells and marsh waters in the swamp zones, between 1994- 1997. Soil samples analysed in this study were collected during a well drilling in December 1996. Water samples were analysed by high pressure liquid chromatography (HPLC; major actions and anions) and inductively-coupled plasma mass spectrometry (ICP-MS; trace elements). Dissolved organic carbon was measured by low temperature chemical oxidation (LTCO). Soil mineralogy was characterised by x-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), electron microprobe analysis (EMPA), and ICP-MS. The results on water samples suggests the existence of chemical and special heterogeneities of waters in the basin: coloured waters flooding the swamp zone have much higher concentrations of both organic (e.g., DOC) and inorganic ions (e.g., Ca, Mg, Na, K, Al, Fe, Th, Zr) than those from springs and groundwaters form the hills (fig. 1). Nevertheless, these organic rich waters present actions concentrations (i.e., Na, Ca, Mg, K) which are among the lowest compared to that of most world rivers.
Atleast four major mechanisms have been known for biological removal of metalions from liquid effluents, namely, bioadsorption, bioaccumulation, precipitation and volatilisation. In biodegradation, the micro-organisms transform the organic chemicals into innocuous forms, degrade them to carbon dioxide and water, besides decomposing them anaerobically. Biosorption is primarily an adsorption-type phenomenon taking place through electrostatic attraction of metal actions to the negatively charged cell surfaces. Moreover, the chemical composition of the bacterial cell wall also plays a role in biasorption through metal binding to exopolysaccharides, proteins and other functional groups. Anionic and cationic sites are thus available on bacterial cell walls. For example, Gram-positive Bacillus subtilis wall has peptidogycan with COO- groups. In Bacillus licheniformis, the bulk of the metal binding capacity is determined by teichoic and teichuronic acids. Similar mechanisms are operative in Gram-negative bacteria also, where lipopolysaccharides play a dominant role. Bioaccumulation is the process of metal uptake by living microorganisms, dependent on metabolic energy. This requires specific transport systems and depends on metal tolerance of the organisms. Inter- as well as intra-cellular accumulation can occur. In both biosorption and bioaccumulation, metal removal is a direct consequence of the physical content between the metal ions and microorganisms. Metals can also be removed from solution without the need for direct contact, the metal removal being brought about by metabolites generated by the micro-organisms. For example, heavy metals from solution can be removed by the activity of anerobic heterotrophs such as sulphate reducers.
The composition of surface water in the wet zone of Sri Lanka is determined by the NaCl dominated rainwater whereas the rock dominance plays an important role with respect to the composition of dry zone surface water. The rock dominance also plays an important role in the wet zone where Dolomite beds are drained. Faecal contamination is a common feature in the surface water, while loading of phosphorus and nitrogen species from agriculture lands, live stock and human settlements with poor sewerage treatment facilities have promoted hypeutrophication. Pollution by trace elements is confined only to the surface waters intercepting major cities and urban centres. With respect to organic residues, the impact may be cronic. Nevertheless, in terms of water quality, Sri Lanka s wet zone rivers draining the lowland, midland and highland are suitable for domestic water supply after appropriate treatment. Reservoirs, irrigation tends, and rivers draining the lowland dry zone are suitable for wildlife propagation, agriculture, industrial purposes and aesthetic enjoyment. Urban canals such as Mid-Canal in Kandy and Nau Oya in Nuwara Eliya have been subjected to severe organic and inorganic pollution. Care should be taken when hypeutrophic water is being used for drinking even after chlorination. It is extremely important to determine the concentrations of organic residues of commonly used pesticides even in the water treated for drinking.
The Western Ghats hill range, extending from Tapi estuary to Cape-Comorin is one of the major physiographic divisions of India. It is the watershed of Peninsular India. It contains some of the vestiges of Tropical Evergreen Forests left in the country and is endowed with rich mineral deposits, besides being the provenance of sediments in the western passive continental margin of India. The hill range displays contrasting diversity in physiographic setting and lithological and biological characteristics, which may reflect in the nature and extent of sediment load and nutrient influx into the western continental margin.
River-backwater system is very dynamic system. Transfer of mass occurs from one to another. C and P distribution between the two has been studied in this paper. There is not much variation in bicarbonate concentration in rivers between monsoon (6.4-13.4 mg/L) and post monsoon (8.2-15.7 mg/L). Spatial variation also is not significant among the rivers south of Palghat Gap. But there is marked increase in HCO3- concentration as one crosses the Palghat Gap. Variation of HCO3- in backwater lakes is dependent on the level of sea water intrusion and varies from 3.3 to 90.3 mg/L. PO4 concentration is low ranging from 0.01 to 0.17 mg/L. There is higher PO4 concentration in backwaters as compared to rivers. Most of sediment carbon in rivers and backwaters is organic in nature. Sediment bound P is also high indicating anthropogenic influences. CH4 emissions from backwaters ranges from 10.97 to 210.59 mg/m2/hr. This variation is in accordance with the salinity gradient.
The amounts of TSS in our samples are very low. The pre-monsoon batch has only two samples (one from the estuarine region of Keedhri not belonging to the first group (< 15 mg/l). The mean TSS of the pre-monsoon samples without the two deviations is 5.38 mg/l. Within the monsoon samples this relationship is different. 50% of the samples belong to the second class (15 - 50 mg/l). Six of the eighteen samples of this batch fall into the first class (0 - 15 mg/l) and three belong to the third class (50 - 150 mg/l). Interestingly, the latter ones are all exception all from up and midstream regions. Samples of the first class have a mean of 7.87 mg/l, second class samples a mean of 28.27 mg/l and the Chaliyar samples contain on an average 84.44 mg/l. Comparison of the TSS values from upstream to downstream no regular behaviour in the pre-monsoon samples, but the monsoon samples show an increasing amount of TSS in the flow direction. The content of particulate organic carbon (POC) ranges between 1.92 and 34.26% of the suspended matter or between 0.29 and 6.23 mg/C/l. These values are in the range of 0.5 up to 40% POC described by MEYBECK (1982), but two samples have POC contents of 34.26 and 23.76% respectively. These tow samples were taken in or behind reservoirs in the dry period with low fresh water input with high biological production. Assuming that 59% of organic material is made up by carbon (MEYBECK, 1982) this would mean for reservoir sample that 70% of the TSS has an organic origin. DOC measurements was done only on the samples of the second and third field trip. Since no stations were repeated it is not possible to see seasonal fluctuations on DOC-content. The total amounts range between 0.51 and 37.29 mg/l. The monsoon samples range between 0.5 mg/l and 6.23 mg/l with a mean of 2.20 mg/l. The lowest pre-monsoon sample has a value of 2.11 mg/l, the whole batch has a mean of 10.91 mg/l. The calculated sediment discharges vary from 14.78* 103t/yr up to 486.32 *103 t/yr and give sediment yields from 8.67 to 166.38 t/lm2/yr. Load vs. runoff gives no correlation at all, while the correlation between yields and runoff is not meaningful but displays at least an increase in the yield with increasing runoff. Plot of yield against basin area shows an increase of the yield with increasing basin area but has not a good correlation coefficient. In comparison with it displays the load vs. basin area plot a very good correlation with increasing load during increasing basin area and r2 = 0.92.
Analysis of selected samples of ground water, aquifer soil, surface soil and river sediment of Bangladesh flood plain and Nepalese Teras for arsenic and iron shows that the presence of iron is preponderant in relation to arsenic and there is no significant correlation. Leaching experiments on arsenic containing aquifer soil under various pH and redox conditions show significantly different rate of release of arsenic from the solid to aqueous phase. At high pH (1N NaOH) a mixture of glucose and HCHO gives rise to fast release. At pH 8.5 the initial rate of release under pure oxygen atmosphere and H402 is much faster than that in a reducing environment comprising glucose and HCHO. The rate of release in reducing condition is linear where as in oxidising condition the initial rate is fast which then slows down considerably over time.
The dissolved phosphate in the Lower Ganges-Brahmaputra-Meghna (G-B-M) river system, Bengal basin, Bangladesh was studied during 1991-93 to determine its distribution in the basin and its annual flux to the Bay of Bengal. The concentration of dissolved PO4-3 varies from 0.32 to 3.16 æmol.l-1 in the basin. The spatial variation of dissolved PO4-3 is not conspicuous. However, the concentration of PO4-3 is high during monsoon and pre-monsoon period and is related to the turbidity of the river. Dissolved phosphate shows good correlation coefficient with major cations, and inorganic processes could be dominant in regulating phosphate concentration in the basin. However, apatite is not a major regulating solid-phase which controls the concentration of PO4-3 in the basin. The discharge weighted mean concentration of phosphate in the Lower G-B-M system is higher than the world average. The river system contributes 105 x 103 t.yr-1 of dissolved inorganic phosphate into the Bay of Bengal which accounts for about 10% of the total dissolved inorganic phosphate flux to the world oceans annually. The concentration of PO4-3 in the Lower G-B-M river system is within the range of other major South East Asian rivers.
The environmental contamination by pesticide residues are of great concern due to their bioaccumulation and persistent nature. Organochlorine pesticides, HCH (hexachlorocyclohexane) and DDT (dichlorodiphenyl-trichloroethane) are among the most persistent and globally distributed organic pollutants. Since the introduction of organochlorine pesticides in late 1930s the residues of these compounds have been found in many parts of the World. In India the organochlorine insecticides, DDT and HCH were used extensively for agriculture and other public health programmes which accounts nearly 77% of the total consumption. The Tamiraparani river is one of the perennial river in South India which is fully utilized for agriculture purpose. Water and bed sediment samples were collected during monsoon and summer seasons and analysed in GC using Electron Captured Detector (ECD). Based on our observation, the samples collected during monsoon period carries maximum loads of HCH and their alpha, beta,gama and delta isomers. The total HCH concentration in water samples ranged from a minimum level of 70 æg/L to the maximum level of 900 æg/L. Elevated concentrations observed at 3 locations in the lower reaches of the basin (Agaram-400 æg/L; Pudukottai-700 æg/L and Mullakadu-900 æg/L) explains the agricultural drainage canal carries maximum load directly from the cultivated lands. The average concentration of HCH (600 æg/L) in Tamiraparani basin is significant when comparing with other major World rivers (Nile, 20 æg/L; major Malaysian rivers, 320 æg/L; Ganges, 2200 æg/L and Yamuna, 660 æg/L). The sediment samples show similar distribution pattern for HCH compounds. On the other hand the DDT compounds show erratic distribution throughout the basin. Similarly in urban area (Tirunelveli) as well as samples collected near Dam and Anaicut such as Tenkasi and Gadana show higher concentrations due to the influence mainly of water stagnation which ultimately leaches out and partly due to higher discharge of organic pollutants. Good positive correlations were observed between finer fractions and organic matter indicates finer fractions acts as scavenger for discharged organic pollutants. The distribution pattern of various DDT isomers in sediment samples are in the following order OP DDD > OP DDE > PP DDD > OP DDT and PP DDD. The lower concentration of DDT compounds (0.04 æg/g to 0.1 æg/g) in both water and sediment samples in many places explains the restricted use and their non degradability. The variation of pesticide transport in the Tamiraparani river basin is discussed in this paper.
Red river system (RRS) is the biggest one in the North Vietnam. Its total basin area is 154,720 km2 with 46% located in Vietnam, the rest is in China and Laos. RRS consist of 4 main rivers: Thao, Da, Lo and Hong. The total length of Red River (RR) consists of Thao and Hong RIvers is 1,126 km which 510 km is in Vietnam territory. RRS has 3,630 m3/s discharge, total water volume is 114 km3. Every year RRS discharge 114 million tons alluvia to the sea ranging from 1000 g/m3 int the delta to 1700-3000 g/m3 in the upstream area. RRS is in a complicated geomorphologic region. Above 90% of RRs catchment (RRSCA) are high land and mountains. 70% of this area is higher than 500m. The elevation decreases in NW- SE direction, towards the Gulf of Tonkin. RRSCA is under the influence of South East Asian Monsoon. The rainfall is 3000mm/year at upstream area to 1700-1800 mm/year in the delta. The forest covers now 20.7% the RRSCA. In RRSCA in the Vietnam territory there are 17,781,700 persons with the main urben areas as Hanoi (1,087,000 persons), Viet Tri (185,000), Nam Dinh (220,000), Ha Dong (100,000) and the most important industrial centers in the North Vietnam. The Cu and Zn in the marine water are of 0.0127-0.0813 mg/l and 0.011-0.092 mg/l respectively. These values are over the allowed ones for aquaculture. The other heavy metals are still under the standards. Nutrients are of quite high values for the river water. Entering the estuary region it become smaller by mixing with the sea water and by sedimentation. The concentration of contaminants in sediment of the Red river is studies very little due to no standards in Vietnam for comparison. However in the framework of the KT.03.07 project some sampling and analiysis have been made. In January and October 1993, sampling have been made for the Hong River and its coastal zone. Concentration of Ni, Cr, Cu, Pb, Cd, Zn, As, Hg, PO43-, NH4+, NO2-, NO3-, SiO2 at a number of sites was defined.
A review is made of the trace metal contamination in the three major rivers of Thailand, namely, the Chao Phraya, the Mae Klong and the Bang Pakong. So far, the most contaminated was the Chao Phraya due to the dense population along the lower Chao Phraya Basin. The flow of these rivers are regulated by some dam reserviors or water gate with result in the modification of the water chemistry, a considerable area of the country in the northeast is the basin of several tributaries of the Mekong River but it is not considered here because the Mekong enters the sea through Cambodia and Vietnam further south.
The current data set show that significant changes in discharge between wet and seasons as occurred only in 1992 where the discharge were 4 times higher than the other years. The BOD and COD did not change among sampling sites with lower concentration in rainy season (November) 1992. There is a significant increase at J. Demangan (after Ledoyo dam). Distribution of BOD and COD showed increased pollution loads in relation to the discharge trend as in seen in November 1992 and 1997. The effect of reservoirs are visible in nutrient NH4 reduction only when the concentration is high. BOD and COD was significantly affected by discharge rates, the higher the discharge the larger their pollution load. It indicated that the higher precipitation could flush out the domestic water into the river. BOD and COD in the urban vicinity are showed relatively low, but with increase in discharge (about 6 times in this case) these parameters increase drastically too. Almost all the nutrients were high and showed large fluctuation especially NH4, NO2 P total, but did not vary much discharge.
Hydrological structure revealed a dominant plume running far away from river mouth and prolonged toward the Southern. The lack of grazing was the reason of high production of phytoplankton which appeared in the plume. The sudden decrease of chlorophyll, which occurred at the fringe of front was estimated as high grazing rate of zooplankton. Some domains in which the risk of eutrophication was predicted by model of principal components analysis in combining with mapping and regressive model.
** Institute of Biogeochemistry and Marine Chemistry,
University of Hamburg,
Bundesstrasse 55, D-2000,
Hamburg 13, Germany
The sediment cores of Mansar and Surinsar lakes of Jammu, have been investigated for their biogeochemistry. The study revealed that C/N ratio supported by d 13C values represent the primary source of organic carbon derived from terrestrial vescular land plants. The poor total nitrogen content, low AA/AS ratios, low AA-C and AA-N% and lighter d 15 N% suggest terrigenous organic matter higher in lignin or carbohydrate contents. The variation in the organic carbon and total nitrogen content in the cores is related to fluctuation in rainfall and changes in climatic conditions (arid drying) through time. The variation in the rate of sedimentation in the Mansar based on Pb210 estimation gives higher 10 mm/yr in the northern flank and 7.7 mm/yr in the southern and 7.2 mm/yr in Surinsar lake which also contribute in the input of terrigenous organic matter to the lake sediments.
The sediment processes in Hudson and Columbia River estuaries are discussed to understand the turbidity maximum formation. One of the turbidity maxima in the Hudson River estuary is formed by resuspension of the bed materials by tidal events combined with changing channel bottom topography. Lagrangian sampling was employed in the Hudson River estuary to understand the sediment resuspension patterns on a spatial scale. The turbidity maximum in the Columbia River estuary exists due to tidal forcing and eulerian sampling mode was attempted to study the sediment suspension on a temporal scale. Primary particle size distribution (enrichment of fines) in the Hudson estuary is reflective of hydrodynamic sorting and entrapment of coarser particles by the Troy Dam in the upstream. In the Columbia River estuary, a hysterisis between maximum suspended sediment concentration (SSC) and peak tidal range is observed during the neap-spring transition. Variations in resuspension intensities and aggregation patterns in the Columbia River estuary compared to other world estuaries are probably due to the coarser nature of the particles in the estuarine turbidity maximum. Conceptual models are proposed to explain sediment processes in the Hudson and the Columbia River estuaries.
Mangroves are, on a global scale, exposed to many single destructive events. They often die a slow death, a process that sometimes lasts for many year and goes largely unnoticed. The commutative effects of natural disasters, clear- cutting over logging, fish and reclamation as well as fragmentation threaten their continued existence with increasing urbanisation and industrialisation, coastal areas of all tropical littoral countries have been subjected to considerable environmental stress. Factors which can effects these areas are: - deforestation, oil spills, domestic swage and industrial effluence s heavy metals, pesticides,. mining activity and herbicides. There is a little doubt that petroleum and its by products can be harmful to mangroves because of their toxic nature. Presumably damage from oil spills to mangroves result from mechanical clogging of lenticles and air hoots of prop roots and pneumatophores. A spray of mixed sea water and oil blown into leaves cause more damage third the spill itself. Phizo phora was found to be more resistant to oil spill than Avicannia (Jagtap & Untanwale, 1980). Domestic sewage and industrial effluents contain almost all possible source in pollution to any Marine area. There discharge causes reduction in species diversity and sometimes reduction in productivity and affects the nursery grounds for fishers. So knowledge on heavy metal pollution in mangroves is very important which throws light on the degree and sources of metal pollution, transport, fate and bioavailabnilith of the metals concerned. Information on this line in mangroves in scarce, because no natural or background data on heavy metal levels/value one available. In recent year for studies were attempted in this line. Tam & Wang observed low heavy metal come in the sediments in the sea ward regions, most of them were not extractable, and therefore assume to be non bioavailable, except the occurrence of few hotspots of excess concentration of metals dumped by local construction, industry, tourist domestic dumping and metal wastes. In Pichavaram, metal enrichment in mangroves in 4-5 times greater than adjacent estuarie and coastal sediments. In Brazil also higher accumulation of metals in mangroves is observed earlier. Thus the mangrove sediments acts as trap/sink or filter for the heavy metals and simultaneously released into the water and biologic system and food chains, which may affect the entire survival of the total mangrove forest (eg.) Aquatic Farm and Flora in the mangrove are affected alike by Cd. 10ppm of Cd is sufficient to kill fishes in one day, 2ppm of Cd take 10 days. Hard water afford protection against the harmful affects of Cd. Increasing salinity also reduces the Cd toxicity, but Cd is Less toxic to plants than methyl mercury or Cu, but is similar is toxicity to Pb, Ni, and Cu (Tam et. al., 1995). For mangrove plant Cu and Pb are essential in lower Qualitative and toxic is excess, where as Pb, and Cd are not at all needed and are toxic to the plants. Depended on the anthropogenic level of contamination their environmental status are predicted.
** Wetlands Center, School of the Environment, Duke University, Durham, NC 27706
* Corresponding author at: Duke University Wetlands Center Everglades Field Station,16139 Okeechobee Blvd., Loxahatchee, FL 33470.
Everglades sloughs are alkaline hardwater systems. Water column dissolved phosphate (5 æg/L) and TP (9 æg/L) concentration in the sloughs are typical of oligotrophic waters. Molar ratios of dissolved inorganic nitrogen and phosphorus (DIN: DIP = 28:1) in the surface waters suggest that P may be limiting the aquatic primary productivity in the Everglades sloughs. Variations in water column TP and TN in the sloughs were inversely related to the water depth fluctuations (p<0.0001) suggesting the strong link between hydrology and nutrient regime in the Everglades. Periphyton and macrophytes in the sloughs exhibited N:P ratios indicative of depletion in P relative to N. The N:P ratios in the Everglades slough communities were in the very upper range of values reported for aquatic plants from other ecosystems. The N:P ratios in periphyton were higher than macrophytes suggesting that the extent of P depletion was even greater for periphyton. As a result any introduced inorganic phosphate was taken up rapidly by the periphyton reducing the water column PO4- P to near background levels. Our results suggest that C:N:P ratios of the periphyton provide a reliable measure of the P-status of the Everglades sloughs whereas the water column P concentration may not truly reflect the P-status of the system. In addition to regulating the water column P concentration the periphyton mat also plays an important role in oxygenating the water column of the sloughs. Experimental results show that a decline in periphyton mat cover will result in a significant decrease in the water column dissolved oxygen concentration and may also lead to other ecosytem changes by enhancing the PAR availability to the slough bottom. The integrity of the periphyton mat is therefore crucial to the protection of the Everglades slough community.
Wetlands are the largest natural source of methane (CH4) accounting for about 20% of the total global annual emissions. The increased atmospheric CH4 concentration for the last several hundred years are primarily due to human activities, whereas pre-industrial sources of methane were primarily due to natural sources. There are considerable differences in emission rates from different types of wetlands mainly due to the complexity in ecology and partly due to anthropogenic disturbances. In this paper, the emission of CH4 from different coastal wetlands of South India have been measured throughout the year. Monthly variations in CH4 emissions showed distinct trends in the unpolluted coastal wetlands (0.52 to 20.30 mg m-2 hr-1) than in polluted wetlands (1.91 to 45.97 mg m-2 hr-1). Several environmental forcing factors such as temperature, salinity, sulphate, organic matter, oxygen, substrate, etc., in addition to human additions were found to control methanogenesis and its emission to the atmosphere. A clear decline in emissivity characteristics could be noted in these coastal wetlands due to the influence of salinity and sulphate which inhibited methanogenesis in these environments. However, due to diverse human activities the CH4 emission is almost double in polluted wetland sites. Based on the Se observations, CH4 emission from coastal wetlands along the Indian coastline has been computed (0.68 to 13.06 x 109 g m-2 yr-1).
The dynamic processes of the matter transfer are studied in a Mediterranean land- shelf-basin.In this system an extended drainage area of 55.5 x 103 km2 with major and small rivers as well as ephemeral streams, influences the transfer of matter in the marine environment. The total annual discharge is estimated in 10.2 x 106 m3 of water and the catchment area could represent a sediment supply of the order of 3-4 x 106 tonnes/year. The deposition of the sediment load discharged by rivers results in a deltaic accretion of the order of 1.0 - 1.3 km2/year. Sediments are accumalated on the shelf of the order of 2.17 x 106 tonnes/year, and in the basin 0.3 x 106 tonnes/year, indicating the role of the shelf-plateau as a natural sediment trap . On the shelf 70,000 tonnes/year of C are buried whereas in the basin only 13,500 tonnes/year of C.
Martin J. Haigh,
Oxford Brookes University,
Prague, Czech Republic.
Almora, U.P. India.
This report examines climatological and hydrological data collected at Animal Park Experimental Catchment, Almora, U.P., between 1989 and 1995. Preliminary geochemical tests yield results that may be fairly typical for a relatively undisturbed forest headwater. This is a near neutral pH, high conductivity (K25/uS/cm) stream. Base flow concentrations of Ca2+, K+ and Mg2+ are relatively low for the region, as is sulphate. Nitrate and ammonia show peaks that may be related to land management activity. The proportion of dissolved to suspended load is high (1.27:1). It may be that the construction of check-dams in the later 1970s has shifted the Physical/Chemical Load ratio by trapping sediment within the basin. Statistical analyses show that suspended and bed-load sediment transport are strongly correlated with runoff and hence that they are transport-limited. By contrast, dissolved load transport is supply limited. Dilution effects create a negative relationship with runoff and positive relationship with evaporation.
Redox reactions exert major controls on the occurrence of nitrate, chromate and arsenate in ground water. Nitrate levels can be lowered by denitrification in the presence of soil biota or by electron donors like pyrite in deep aquifers. Cr(VI) and As(V) species, on the other hand, are strongly adsorbed an positively charged surfaces of iron hydroxide minerals. However, their retention is affected when competing anions are supplied through increase ln salinity or fertilizer application.
In the world today the total load of mercury emissions is about 6 to 7.5 thousand tonnes per year. The emission due to human civilisation got a spurt since the days of gold and silver rush since the sixteenth century. The effluents carrying mercury ultimately unloads it in lakes and seas. Fish containing the biomethylated mercury poses as the major source of mercury contamination in man, who is under increasing toxicological pressure from other adverse eco-components as well. The factors controlling mercury contamination in aquatic environment and the load generated in the fish-eating population have been shown with response to dose- response relationship and the WHO prescribed limits.In this paper an analysis has been attempted to focus on the major causative factors of mercury contamination through human activities. An evaluation of the recent activities such as construction of dams for hydroelectric power generation, impoundment for other water reservoirs, cutting new lakes, deforestation and erosion of forest soil enriched in toxic metals has been attempted with notes on the flood perturbation of the eco- stability. An overview has been made of the salient aspects accelerating the processes of methylation in the present day ecosystem.
Andhra Pradesh state accounts for 8% of country s population and hosts same percentage of forest cover. Industrial growth, urbanization has increased several folds since past four decades. Major industries such as power, pharmaceuticals, paper, cement, sugar, iron and steel, chemicals, fertilizers, textiles etc in Government and private sectors contributed to the states economy and improved the standard of living of the people. The industrial growth has compelled to over exploitation of natural resources such as forest products, mining of minerals including coal, limestone, iron ores, bauxite, base metals, barytes, slates and also led to the over utilization of water resources. Explosion of population by two times since the formation of the state had increased the stress on agriculture sector, which forced to invade the forests, converting them into agricultural fields. Forest cover has diminished to bare 43,000 sq.km area. Over exploitation followed by industrial development had polluted air, water, and soil. Increased vehicular traffic in urban areas such as twin cities, Vizag, Vijayawada etc. has polluted air due to smoke and particulate emissions. Water pollution is mainly due to discharge of untreated industrial effluents, in streams, tanks, rivers, lakes and ocean. Dumping of municipal waste, over drafting of ground water, seawater intrusion, and soil erosion have also increased the level of pollutants in various water bodies. Recent growth in shrimp culture had unbalanced the entire coastal ecosystem causing a permanent damage.
Central Mining Research Institute,
Regional Centre, CBRI Campus,
Roorkee - 247667 (U.P.), India
Mineral resources are an integral part of any country s economic potential. There has been mining activity since civilisation started initially for making ammunition for hunting to the present for nuclear power, hydrocarbons, metals etc. Pollution arising out of the mining activities can cause serious damage to the environment, unless of course remedial measures are taken. This paper discusses the various types of environmental pollution caused by exploitation of mineral resources. Physical and chemical pollution caused due to mining are illustrated with three case studies
Incorporation of heavy metals in coral skeletons is a reliable indicator of industrial pollution in the marine environments. Coral colonies of Montipora digitata, Montipora foliasa, Montastrea annularis, Acropora hycinthus, Pocillopura damicornis, Acropora cervicornis and Acropora nobilis were collected in the reef areas of Tuticorin group of islands. Metal concentrations determined by Sequential Plasma Emission Spectrometer reveal that higher concentration of Sr and other metals like Zn, Fe, Ti, Cu, Mo, Cr, Ni, Hg, Sn, V and Cd are in decreasing concentrations in the coral skeletons. These metal concentrations in the coral skeletons are many folds than the concentrations of heavy metals in standard sea water. Presence of strontium in coral skeleton inhibits alteration of aragonite to calcite. Concentrations of other metals in the individual coral species are ranging from 0.098 ppm (Acropora hyacinthus) to 0.90 ppm (Montipora digitata). Coral species are bio-indicator and concentrations in the species are relevant to public health and pollution concern. In the study area the marine pollution is traced to fly ash content of Thermal Power Plant and other effluents discharging from chemical industries.
Conservation of freshwater ecosystems is paramount importance to all the developing countries. In future in many countries, the most important and visible gains made in meeting basic needs - drinking water requirements, establishing basic health facilities and food security could be wiped out if the freshwater ecosystems are continued to degrade at the present rate. Many developing countries are facing two pronged challenges in conserving the freshwater ecosystems. First the present understanding about the properties need to be revised. Primarily that the conservation freshwater ecosystems are not the priority of poor countries has they need to work on improving the basic needs of the people and then they can work on improving the status of the ecosystems. This has to be fundamentally corrected. Conservation of freshwater ecosystems has to be made integral part of meeting basic needs. Second, the general understanding that conservation is expensive and technical business. Some extent it is true but many developing countries do already have human and technical resources. They simple need to revive some of the water management systems, which were time tested but adopt to suite the present socio-economic situation. The future of the freshwater conservation in some of these countries depends on the extent they integrate the freshwater management at the basin level and treating water as finite resources which has implications to economic, social and environmental status of the country. Proper policies and institutions have to be placed at appropriate level to deal with emerging freshwater crisis.
** Institute of Biogeochemistry and Marine Chemistry,
University of Hamburg, Germany
Samples taken from twelve rivers , each draining in N-S direction into the Atlantic Ocean via the Lagos and Lekki Lagoons were analysed for their biogeochemical parameters. The southwestern part of Nigeria represents an area with a high population density, where surface waters are used as vehicle of domestic and industrial wastes. However, most of these rivers also serve as important sources of water supply: the Ogun river, for instance, supplies the sprawling city of Lagos (11 million inhabitants) with water from the Oyan dam, located 60 km northwards. The rivers under investigation are characterised by low relief with a N-S gradient; they all take their sources from a NW-SE striking escarpment at an elevation of about 500 m in the north-west, but slightly lower in the south-east. Three vegetation zones can be identified in the study area : the savannas are well- marked against the high forest vegetation in the central and eastern sector of the area. Extensive natural forests and forest reserves have disappeared due to rapid urbanization. Swamp and mangrove forests cover the southern coastal and riverine areas adjacent to the lagoons. The rivers were sampled during the flood period when discharges were some 25 to 100 times the dry season values. The paper dicusses results of the dissolved nutrients, including nitrates, phosphates and silicates, as well as the particulate organic matter.
Prof. V. Subramanian
Tel. : +91-11-6107676. Ext. 2316 School of Environmental Sciences
Telefax : +91-11-6106501 Jawaharlal Nehru University
Fax : +91-11-6165886, 6172438 New Delhi - 110 067, INDIA