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Triterpenoids and fatty alcohols were identified from the sediments of five mangrove ecosystems (Kunjimangalam, Pazhayangadi, Pappinissery, Thalassery, and Kadalundi) in the northern Kerala coast, ...

This study has been carried out to understand the geochemistry of elements namely, iron (Fe) and phosphorus (P) in the core sediments of an urbanized tropical mangrove ecosystem along the Southwest coast of India. The study revealed the coupling of iron and phosphorus in which the reductive conditions induced reductive dissolution and upward transport of Fe, causing surface coprecipitation of phosphorus incorporated Fe oxyhydroxides. The accumulation and transformation of phosphorus were significantly influenced by processes viz., phosphorus regeneration due to organic matter mineralization and adsorption to inorganic iron oxides/Ca bound minerals in the surface sediments, and phosphorus retention in the sedimentary column by transformation into refractory organic phosphates. Bioavailable phosphorus (BAP) accounted for more than 50% of TP, so that the mangrove sediments act as an important internal nutrient source of iron and phosphorus for coastal eutrophication.

Aliphatic hydrocarbons in the sediments of the estuarine mangrove forests of Cochin region, Southwest coast of India were characterized to assess the sources of organic matter (OM) and to v...

Distribution and ecological risk assessment of trace metals were carried out in the core sediments of a highly urbanized tropical mangrove ecosystem along the Southwest coast of India. The metal distribution pattern was as follows: Co, Cu, Ni and Pb adsorbed onto Fe oxyhydroxides and fine grained sediments; Cd and Zn preferential adsorption by organic matter and Cr scavenging by Mn oxyhydroxides. Cd, Pb and Zn were significantly enriched in upper sediments, while Cd, Ni and Zn were present in metal exchangeable fractions. Geoaccumulation index (Igeo) suggested that the study area showed moderate to strong pollution of Cd and Zn, whereas unpolluted to moderately polluted with respect to Co, Cr, Cu, Mn, Ni and Pb. Cd enrichment caused high ecological risk, primarily attributed to anthropogenic activities. Mangrove ecosystems are efficient sequester of trace metals but anthropogenic addition can cause significant fraction of exchangeable metals and pose high ecological risk.

Flexible micro-cellular open porous 3D polymer foam silica aerogel composites with exceptional oil sorption characteristics were prepared by implanting silica aerogel in the interstices of foam substrates. Silica aerogels were engineered from silane precursors namely tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) adopting economical, energy efficient and scalable ambient pressure drying technique. These flexible composites exhibited outstanding structural ruggedness. The foam-aerogel composites deliver superior hydrophobic characteristics in terms of contact angle data. The aerogel composites recorded an oil uptake of 31.3 g per g of the composite for engine oil and the uptake was very swift. Mechanical squeezing enables near complete oil removal from the composites. The foam aerogel composites displayed superior recyclability features, as first time absorption is retained even after 10 cycles of repeated squeezing and re-absorption operations.

Efficiency of therapeutic compounds could be enhanced by encapsulation and covalent attachments to a biomaterial carrier. Complex formation with humic substances is valuable techniques to improve bioactivity of natural products. Fractal structures of humic substances also have adjacent carboxyl and hydroxyl groups. Along with molecular bonding property, reduction-oxidation and association-dissociation capacities of humic substances are considered this as a biomaterial for transform, other molecules, and substances. Immune system responses of humic acid stimulates in the human body. However, pharmaceutical importance of humic substances, demands on evidenced efficacy and a clearly defined chemical composition of the preparations used. Toxicological safety standards also have to be evaluated. This review summarises the application of humic substances as pharmaceuticaly important biomaterial. Research on this zone opened up an application for humic substances in pharmacogonasy.

The seasonal variability of free and protein bound amino acids (AAs) in the sediments of mangrove ecosystem, west coast of India were studied. AAs exhibited significant variability with depths in the sediments of two mangrove ecosystems, Mangalavanam and Vypeen, situated on the west coast of India. Of the ten AAs detected, serine (Ser) was the most abundant followed by threonine (Thr), glycine (Gly), aspartic acid (Asp), tyrosine (Tyr), glutamic acid (Glu) and alanine (Ala). The trend in AA relative abundance in the sediment and leaves exhibits a close similarity indicating a major influence of plants in the supply of these compounds to the sediment. The most common AAs at both stations are Asp, which is abundant in sediments with a large organic inputs followed by Glu, which is abundant in phytoplankton and marine bacteria. Ser, Thr and Gly, which constitute diatom cell walls, were also found in significant concentration. The changes in relative abundance of various AAs with depth indicate significant seasonal variability. This may be due to the selective microbial utilization of these AAs at different depths. Principal component analysis (PCA) revealed that the first principal component, which is the degradative index (PC I ) has ca . 84 % of the variance at Mangalavanam and

Background. Perchlorate is an anion that occurs as a contaminant in groundwater. It originates from the improper disposal of ammonium perchlorate, a component of rocket fuel. The objective of this study was to explore whether the exposure to perchlorate in drinking water had an impact on the thyroid function of the population residing near an ammonium perchlorate plant in Kerala. Methodology. Using an ecological study design, we compared the serum levels of thyroid-stimulating hormone, thyroxine, and thyroid peroxidase antibodies among a representative sample of 289 study subjects from the area surrounding the ammonium perchlorate enrichment plant to 281 study subjects in a control area. Results. The perchlorate concentration in the groundwater varied from 1600 ppb to 57,000 ppb in the 10 samples from the contaminated area and was below 24 ppb in all locations in the control area. No significant differences were found in the mean serum TSH concentration and mean T4 levels between the subjects from the contaminated area and the control area. On regression analysis, perchlorate contamination was not found to be a significant predictor of TSH. Conclusion. This study did not find any significant association between perchlorate in drinking water and changes in thyroid hormone levels. Our findings indicate the need for further investigation of this hypothesis using urinary perchlorate as a measure of individual exposure.

Polycyclic aromatic hydrocarbons (PAHs) showed significant seasonal dynamics in surface sediments of a tropical ecosystem (Cochin estuary, south west coast of India). Concentrations ranged from 304 to 5874 ngg − 1 in pre-monsoon, 493 to 14,149 ngg − 1 in monsoon, and 194 to 10,691 ngg − 1 in post-monsoon. The estuary was moderately contaminated with low molecular weight PAH fractions, which increased rapidly during the monsoon season indicating land/river runoff as the major transport pathway. The dominance of 2–3 ring fractions in the PAH indicated petrogenic and low temperature combustion processes as major sources, while the very low levels of 5–6 ring components indicated low contribution from pyrolytic sources. Low molecular weight fractions were higher in concentration than the Effective Range-Median (ERM) levels, whereas high molecular weight PAHs were lower than the Effective Range-Low values (ERL). Calculated carcinogenic toxicity equivalents (TEQ) values ranged from 1 to 971 ng g − 1 in the surface sediments.

Renjith, K.R.; Joseph, M.M.; Ratheesh Kumar, C.S.; Manju, M.N., and Chandramohanakumar, N., 2016. Nutrient distribution and bioavailability in a tropical microtidal estuary, southwest India. This study estimates the spatial and seasonal variations of phosphorus and nitrogen fractions in the surface sediments of Cochin Estuary to assess their bioavailability and the factors governing biogeochemical distribution. Seasonal variations of the dissolved nutrients suggest that phosphorous buffering activity is very high in the estuary, and there could be a nitrogen limitation in the absence of any external input. Iron-bound and calcium-bound inorganic fractions were the major forms of sedimentary phosphorus in the central estuary. Upstream regions were characterised by higher proportions of organic phosphorus, mainly as alkali-soluble fractions. Bioavailable fractions ranged from 2.61% to 90.43% of total phosphorus and show a significant increase during the lean pre-monsoon period. This increase, which ...

Surface sediment samples from five mangrove ecosystems along the Kerala coast, north of Kochi were analysed for elemental ratios, stable isotopes of carbon and hydrocarbon biomarkers (n-alkanes, n-alkenes and hopanes) to assess the sources and early diagenesis of sedimentary organic matter. The elemental and isotopic ratios along with sedimentary chlorophyll a content, suggested substantial contribution of planktonic organic matter apart from mangrove/terrestrial derived organic matter. The sources of organic matter showed variability in relation with the geographical setting of mangrove systems as well as with seasons. The n-alkanes in mangrove sediments consist of organic matter derived from varying contributions of planktonic, bacterial and terrestrial sources. The distributional features of n-alkanes with low molecular weight ( C 20 ) indicated the preponderance of algal derived organic matter, whereas the unresolved complex mixtures for low molecular n-alkanes indicated active microbial reworking. The n-alkane derived molecular indices enable the effective source appropriation of different end members in the study region, while diagenetic alteration products of lipids such as n-alkenes, branched alkanes and n-alkylcyclohexanes along with hopanes are indicative of organic matter diagenetic pathway in sediments. The n-alkenes in the study area probably derived from decarboxylation reactions of unsaturated fatty acids and other terrestrial inputs. The higher input of mangrove/terrestrial derived organic matter is evident by the average chain length data. Information obtained using biomarkers will allow to discriminate organic carbon sources in these mangrove ecosystems.

Biomass productivity, lipid content, lipid productivity and fatty acid methyl ester (FAME) profiles of three pelagic and two benthic diatom strains (Chaetoceros calcitrans, Thalassiosira sp., Skeletonema sp., Navicula sp., Nitzschia sp.) were evaluated to identify potent strains for biodiesel production. Navicula sp. and Thalassiosira sp. were found to be higher biomass producing strains, whereas Nitzschia sp. showed lower biomass productivity. Lipid content was higher for Thalassiosira sp. and lower for Skeletonema sp. Navicula sp. was found to be the most suitable biodiesel feedstock in terms of saturated (65.59%) and monounsaturated (27.92%) fatty acids. Cluster analysis of the strains based on growth parameters and FAME profiles revealed close resemblance between Chaetoceros calcitrans and Skeletonema sp. and also between Thalassiosira sp. and Navicula sp. But Nitzschia sp. was secerned from the other strains. Principal Component Analysis (PCA) provided a confirmation that lipid content alone ...

The spatial and temporal variations of some trace metals in the surface sediments of Cochin Estuary were analyzed along with their geochemical associations to identify the possible sources, bioavailability and the health risks posed by them. The dominance of kaolinite and suggested that clay minerals distribution is influenced by sediment sorting. Total metal analysis revealed enrichment for Cd, Pb and Zn due to anthropogenic activities. The speciation analysis established that notwithstanding the large availability, carbonate as well as organic and sulfides bound fractions showed negligible associations with most of the metals. Hydrous Fe–Mn oxides appeared to play a major role in controlling the fate and transport of these metals in the sediments of Cochin Estuary. Lower contribution of the residual fractions for Cd (21%–26%), Pb (

Phthalic acid esters (PAEs) are a group of endocrine-disrupting chemicals listed as priority pollutants by United States Environmental Protection Agency (USEPA, 2009). This study provides baseline information on seasonal distribution and contamination status of six phthalic acid esters (∑6PAEs) in sediments of a tropical estuary (Cochin-India). In general, the sediments accumulated more PAEs during the post monsoon (mean 2325 ngg−1; between 1402 and 3121 ngg-1) and monsoon (mean 1372 ngg−1; between 331 and 4015 ngg−1) periods indicating land run off as the major transport pathway. Moderate run off and comparatively high residence time lead to effective sorption and settling of PAEs in the surface sediments during post monsoon season. Despite a high discharge of PAEs in to the water column, their deposition on to the sediments occurs at a lower rate during monsoon than that post monsoon season. PAEs were (mean 810 ngg−1; between 44 and 1722 ngg-1) lowest in pre monsoon season. The pre monsoon season is characterized by a minimal runoff consequent to the trapping of these organic pollutants in the river catchment area. The mid and high molecular PAEs (DEHP-Di ethylhexyl phthalate, BBP-Benzyl butyl phthalate and DnBP-Di-n-butyl phthalate) were the dominant congeners relative to the low molecular weight congeners (DMP-Dimethyl phthalate and DEP-Diethyl phthalate). DEHP and BBP levels exceeded permissible risk levels indicating a serious ecological hazard to the estuarine ecosystem.

Distribution and ecological risks of Phthalic acid esters (PAEs) are poorly studied in estuarine environments in India. An attempt is made to chart the sources and assess the ecological risk of six PAE congeners (∑6PAEs), present in dissolved and particulate forms in a tropical ecosystem (Cochin Estuary, India). Terrestrial input, as attested by a clear seasonality with substantial enrichment during monsoon (2–28 μg/L and 31–1203 μg/g; dissolved and particulate PAEs respectively) and post-monsoon (1–7 μg/L and 7–321 μg/g; dissolved and particulate PAEs respectively), was identified as the primary source. DnBP (di-n-butyl phthalate) and DEHP (diethylhexyl phthalate) were found to be the dominant species except for dissolved PAEs at pre-monsoon season. Statistical analysis identified two major clusters, in the ∑6PAEs, composed of medium to high molecular weight PAEs (derived from plastic products) and low molecular weight PAEs (derived from cosmetic products). Calculated Risk Quotient (RQ) indicated values indicated moderate to high ecological risk for DnBP and DEHP congeners is a grim pointer to their detrimental effects on human health through consumption of contaminated organisms. Although substantial enrichment of suspended matter gets flushed out of the estuary during monsoon, there is a net PAE accumulation in the estuary during post-monsoon following an increased sedimentary restitution. Data of PAEs generated herein raises a challenge for immediate enactment of statutory legislation to curb and regulate hazardous contamination of estuaries by phthalic acid esters.

This review examines the chemical compositions and bioactivities of mangrove plants belonging to the Rhizophoraceae family. The Rhizophoraceae family of true mangrove plants is the most common and is also widely distributed species. It consists of 24 species across four genera. Of the 24 species, 12 species remain unexamined for their phytochemical constituents. There have been 268 metabolites reported from 16 species. The key phytochemical constituents identified across the family are the diterpenoids and triterpenoids. The major diterpenoids include pimaranes, beyeranes, kaurenes, dolabranes and labdanes whereas the significant triterpenoids are lupanes, dammaranes and oleananes. Disulphides, dolabranes and labdanes are considered to be the chemotaxonomic markers of the genera Bruguiera, Ceriops and Rhizophora respectively.

Surface sediments samples were collected from 9 stations of the Cochin estuary during the monsoon, post-monsoon and pre-monsoon seasons and were analyzed for grain size, total organic carbon (OC), total nitrogen (TN) and stable isotopic ratios of carbon (δ¹³C) and nitrogen (δ(¹⁵N) to identify major sources of organic matter in surface sediments. Sediment grain size is found to be the key factor influencing the organic matter accumulation in surface sediments. The δ¹³C values ranges from -27.5‰ to -21.7‰ in surface sediments with a gradual increase from inner part of the estuary to the seaward side that suggest an increasing contribution of marine autogenous organic matter towards the seaward side. The δ¹⁵N value varies between 3.1‰ and 6.7‰ and it exhibits complex spatial and seasonal distributions in the study area. It is found that the dynamic cycling of nitrogen through various biogeochemical and organic matter degradation processes modifies the OC/TN ratios and δ¹⁵N to a considerable degree. The fraction of terrestrial organic matter in the total organic matter pool ranges from 13% to 74% in the surface sediments as estimated by δ¹³C based two end member mixing model.

The study of phosphorous dynamics in mangrove ecosystems of the northern Kerala coast aims to delineate its relationships with other biogeochemical parameters. Our intension is to check the validity of the hypothesis that these mangrove ecosystems act as an efficient trap of organic phosphorous by acting as P sink. The dissolved inorganic phosphate displayed higher concentration in monsoon that could be correlated with higher P leaching from mangrove litter as well as terrigenous input during wet season. Fe(OOH)≈P was much higher in monsoon (235.23 to 557.70 μg g(-1)) and lower in pre-monsoon (36.50 to 154.97 μg g(-1)), and displayed significant contribution towards the inorganic sedimentary P fractions. In monsoon, adsorption of P on iron hydroxides is enhanced by fresh water conditions, but pre-monsoon is characterised by the reductive dissolution of iron oxy hydroxides and the subsequent efflux of P to water column. CaCO3≈Pinorg may be present as an inert fraction in the sediment matrix, and did not display any interrelationship with other geochemical parameters. The abundant total organic P (25 to 73 %) fractions, largely derived from P bound with humic/fulvic acid, played a major role in immobilising P and regulating its dynamics in the nearby estuarine and coastal environment.

Seasonal studies were carried out from 21 stations, comprising of three zones, of Cochin Estuary, to assess the organic matter quality and trophic status. The hydographical parameters showed significant seasonal variations and nutrients and chlorophylls were generally higher during the monsoon season. However, chemical contamination along with the seasonal limitations of light and nitrogen imposed restrictions on the primary production and as a result, mesotrophic conditions generally prevailed in the water column. The nutrient stoichometries and delta C-13 values of surficial sediments indicated significant allochthonous contribution of organic matter. Irrespective of the higher content of total organic matter, the labile organic matter was very low. Dominance of carbohydrates over lipids and proteins indicated the lower nutritive aspect of the organic matter, and their aged and refractory nature. This, along with higher amount of phytodetritus and the low algal contribution to the biopolymeric carbon corroborated the dominance of allochthonous organic matter and the heterotrophic nature. The spatial and seasonal variations of labile organic components could effectively substantiate the observed shift in the productivity pattern. An alternative ratio, lipids to tannins and lignins, was proposed to ascertain the relative contribution of allochthonous organic matter in the estuary. This study confirmed the efficiency of an integrated biogeochemical approach to establish zones with distinct benthic trophic status associated with different degrees of natural and anthropogenic input. Nevertheless, our results also suggest that the biochemical composition alone could lead to erroneous conclusions in the case of regions that receive enormous amounts of anthropogenic inputs.

Trace metal concentrations (Fe, Co, Ni, Cu, Zn, Cd, and Pb) in the muscle, gill and liver of the fishes Mugil cephalus, Etroplus suratensis, Sillago sihama, and Arius arius collected from the Cochin backwaters during monsoon, post-monsoon and pre-monsoon periods were studied. The seasonal average ranges of these metal concentrations in the muscle, gill and liver of fishes were respectively as follows: Fe (546.51 to 956.05 μg/g, 602.87 to 1028.05 μg/g and 706.72 to 1114.58 μg/g); Co (12.50 to 28.05 μg/g, 21.43 to 35.73 μg/g and 30.90 to 52.23 μg/g); Ni (4.45 to 6.63 μg/g, 6.73 to 14.83 μg/g and 11.59 to 39.18 μg/g); Cu (5.12 to 6.16 μg/g, 17.79 to 30.53 μg/g and 33.19 to 44.70 μg/g); Zn (48.97 to 144.50 μg/g, 89.02 to 246.79 μg/g and 200.82 to 403.40 μg/g); Cd (1.17 to 2.35 μg/g, 2.01 to 3.50 μg/g and 3.49 to 4.37 μg/g); and Pb (1.01 to 1.95 μg/g, 1.32 to 2.07 μg/g and 2.11 to 3.03 μg/g). The elevated accumulation of metals in the fishes was well above the natural background levels during all the seasons a...

The sources of organic matter in three typical mangrove systems of Cochin estuary were assessed for the first time with help of sediment bulk parameters and fatty acid biomarkers. The C/N and δ13C analysis showed intermediate values to that of autochthonous and terrestrial inputs of organic matter, signaling to a mixed origin. The biochemical composition of sedimentary organic matter revealed a dominance of lipids over proteins and carbohydrates, indicating the nutritive or energetic value as well as the freshness of organic matter in all the systems. Fatty acids ranging from C8 to C24 were identified in the study. C20:5n-3 was one of the major fatty acids at station 1, indicating significant benthic phytoplankton contribution. The zooplankton biomarkers C20:1 and C24:1 were also present in appreciable levels, suggesting the tidal influx. Principal fatty acids at station 2 were the zooplankton biomarkers C20:1 and C24:1 implying significant estuarine contribution through tidal influx. The major fatty acid...

Hydrography of the eastern Arabian Sea and associated chemical and biological responses were studied during the withdrawal phase of summer monsoon 2003. The shelf region off the southwest coast of India (10°N–15°N) continued to exhibit upwelling of colder ( 2.0 μM, phosphate >0.8 μM, silicate >4.0 μM) and relatively low oxygenated waters (~180 μM). The vertical advection of nutrients, coupled with anthropogenic terrestrial inputs, enhanced the levels of chlorophyll and primary productivity near the coastal margin off Cochin. The influence of both natural and anthropogenic nutrient loadings on the coastal system of the western continental shelf of India leads to eutrophication and hypoxia with negative impacts on the environment in general and fisheries in particular.

The steroidal composition of the marine sponge Axinella carteri, collected from Lakshadweep archipelago in the Arabian Sea was found to be a prolific source for a variety of rare steroids. The GC–MS study afforded us with the occurrence of 8 steroids belonging to four different types of nucleus, including the unique occurrence of an unconventional steroid A-norcholestan-2-one in Axinella carteri. The biological activity was predicted using the soft ware PASS. It was found that majority of the steroids extracted from Axinella carteri exhibited the potential of being agonistic to nerve growth factor (NGF).

Samples of macro algae collected at random distances from the coral and near shore environment of Lakshadweep archipelago were analyzed for their trace metal content (Fe, Mn, Zn, Cu, Co, Cr, Cd, Pb, and Ni). All the species showed an affinity towards essential elements, and the concentration of Fe seemed to be the highest in all the species, irrespective of their classification. The trace metal content reported in this study was much lower than the limit prescribed by Food and Agricultural Organization (FAO) in seafood for human consumption. None of the species of algae had the tendency to bioconcentrate Pb in their system as the detection level was below 0.1 mg/kg. The metal selectivity index calculated in statistical analysis emphasized the ability of algae to accumulate a particular metal from among the metals studied. To show the similarity between species and metal uptake, a group linkage clustering technique was used and the results were depicted using dendrogram. The marked similarities in the leve...

Background: Turbinaria conoides, a brown seaweed, is a rich source of oxygenated fucosterols which are capable of suppressing the proliferation of cancer cells. Their specific therapeutically significant biological activity is directly related to the unique structural features of the molecule. This study specifically focuses on extracting unconventional sterol molecules (side chain extension) from this seaweed which can be used as a lead molecule to evolve therapeutical agents. Materials and Methods: To isolate unconventional sterol molecule, for structural elucidation and bioactivity study, sufficient amount of T. conoides was collected from Mandapam, an unique biodiverse environment along the Southeast coast of India. State-of-the-art methods available for the purification and characterization of molecule (High-resolution fast-atom bombardment mass spectrometry, ultraviolet-visible spectroscopy, attenuated total reflection–fourier transform infra-red, One-dimensional nuclear magnetic resonance, and two-dimensional nuclear magnetic resonance) were put in. In vitro bioassays (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium bromide, double staining, and flowcytometry) were carried out against A549 and human liver cancer cell line (HepG2) malignant cells to assess the cytostatic potential. Data were statistically validated. Results: A unique unconventional sterol molecule (Turbiconol) with ethyl and methyl group at C-27 was isolated. This molecule induced apoptosis in A549 and HepG2. However, cell cycle assessment revealed G0/G1 cell cycle arrest in Hep G2 and G2/M checkpoint was responsible for the suppression of A549 cell line. Conclusion: A novel unconventional compound, turbiconol, is reported in this study. In vitro results highlight the potential of this molecule in developing therapeutical combination which can be used for novel treatment methods.

The phosphorus fractions in three tropical mangrove systems of Cochin region were analysed by sequential extraction method. Iron-bound phosphorus was the major fraction in the first two stations, while station 3 was exclusively dominated by calcium-bound phosphorus. Compared to other stations, about tenfold increase in total phosphorus content was observed at station 3. This station is a congregation of communally breeding birds, and there is accumulation of bird guano. Mineralogical analysis showed the presence of monetite, a thermodynamically metastable calcium phosphate mineral, in this unique system. The excreta and carcass of the birds in this sanctuary seems to be the reason for the formation of monetite, which is favoured by periodic fluctuations in redox potential. The high mass percentages of calcium and phosphorus by XRF and SEM–EDS analysis confirm the existence of calcium phosphate mineral at station 3. First two stations did not show any noticeable difference in phosphorus fractions and inorganic fractions constituted to about 65% of total phosphorus. But at station 3, inorganic fractions were about 92%. Low C:P ratios and low organic phosphorus content indicated active mineralisation of phosphorus at station 3. Bioavailable fractions of phosphorus at stations 1 and 2 were about 75%, whereas 98% of the total phosphorus was bioavailable at station 3. Since the bulk of the total phosphorus is bioavailable, these mangrove sediments have the potential to act as source of phosphorus to the overlying waters.

Phosphorus fractionation was employed to find the bioavailability of phosphorus and its seasonal variations in the Panangad region of Cochin estuary, the largest estuarine system in the southwest coast of India. Sequential extraction of the surficial sediments using chelating agents was taken as a tool for this. Phosphate in the water column showed seasonal variations, with high values during the monsoon months, suggesting external runoff. Sediment texture was found to be the main factor influencing the spatial distribution of the geochemical parameters in the study region. Similarly, total phosphorus also showed granulometric dependence and it ranged between 319.54 and 2,938.83 μg/g. Calcium-bound fraction was the main phosphorus pool in the estuary. Significant spatial variations were observed for all bioavailable fractions; iron-bound inorganic phosphorus (5.04-474.24 μg/g), calcium-bound inorganic phosphorus (11.16-826.09 μg/g), and acid-soluble organic phosphorus (22.22-365.86 μg/g). Among the non-bioavailable phosphorus, alkali-soluble organic fraction was the major one (51.92-1,002.45 μg/g). Residual organic phosphorus was comparatively smaller fraction (3.25-14.64% of total). The sandy and muddy stations showed distinct fractional composition and the speciation study could endorse the overall geochemical character. There could be buffering of phosphorus, suggested by the increase in the percentage of bioavailable fractions during the lean pre-monsoon period, counteracting the decreases in the external loads. Principal component analysis was employed to find the possible processes influencing the speciation of phosphorus in the study region.

The mangroves of Kerala are fast disappearing due to developmental activities. There are very few studies conducted in the chemical aspects of these ecosystems. The main objective of this study is to assess the spatial and seasonal variation of hydrographical as well as nutrients in mangrove ecosystems along Kerala coast. Five sampling sites least intervened by industries were selected for the study. Sampling was done for a period of six months in monthly intervals. A monsoonal hike of dissolved nutrients was observed in all ecosystems except in the constructed mangrove wetland. The constructed wetland exhibited a different hydrography and nutrient level in all seasons. The mangrove forest in this area consists of the species Bruguiera gymnorrhiza which has been planted since forty years. Key words: wetlands; mangroves; nutrients; season; constructed wetland DOI: 10.3126/jowe.v3i0.2264 Journal of Wetlands Ecology, (2009) Vol. 3, pp 32-42

Surface sediments from the western continental shelf of India were analysed for total organic carbon (TOC), total nitrogen (TN), total hydrolysable carbohydrates (TCHO) and proteins (PRT) during the late summer monsoon (September–October, 2003) and pre-monsoon (March–April, 2004) seasons. The region experienced entirely different hydrographic characteristics and productivity patterns during the two seasons. Low oxygenated, cold, nutrient rich (DO 2 μM) surface waters and the existence of subsurface suboxia were the hydrographic features during late summer due to the persistence of upwelling. Meanwhile, during pre-monsoon the region was oligotrophic and oxygen saturated (DO>200 μ M, NO3

The distribution and speciation of Fe, Mn and Cu in six geographically different mangroves of the south west coast of India have been examined. The metal concentrations in sediments ranged from 0.53–95.44 mg/g for iron, 12.16–325.98 μg/g for manganese and 0.13–243.32 μg/g for copper. The metal levels in sediments were comparable with those from similar aquatic systems. Speciation of metals in sediments and principal component analysis (PCA) of the speciation data indicates that ultimate storage of iron is in the inorganic pyrite form. Manganese and copper exhibit temporary storage by associations with organic matter.

Variability of nature and composition of organic matter in the surficial sediments of mangrove and estuarine systems of Cochin were investigated. Assessment of biochemical composition and elements such as carbon, nitrogen and sulphur were employed for this. Irrespective of the higher content of total organic matter, the labile organic matter was very low in both mangrove and estuarine sediments. Concentrations of biochemical compounds were comparatively higher in mangrove sediments. Total lipids were the dominant class among labile organic compounds in both mangrove and estuarine sediments contributing 51.4% and 45.3%, respectively. Protein to carbohydrate ratio was higher in estuarine sediments when compared to mangroves, indicating low dead organic matter accumulation, probably due to the strong hydrodynamic conditions in estuaries. Correlation analysis showed that sediment texture had no significant correlation with any of the sedimentary parameters in mangroves, whereas in estuaries, it showed significant correlations with most of the sedimentary parameters. Principal component analysis indicated three different dominant processes in mangroves namely mangrove litter addition, diagenesis and other geochemical process like siltation and sorption/desorption, while in estuaries the dominant process seems to be diagenesis.

This paper focuses on the distribution of an important micronutrient element, phosphorus in the various coral reef sedimentary environments of the Lakshadweep Archipelago, in the Indian Ocean. One of the salient features observed is the high concentration of organic and residual phosphorous compared to inorganic phosphorous. This is particularly evident at stations characterised by higher total phosphorous concentrations. The concentrations of total phosphorous decrease with depth because of the upward migration of phosphate produced by mineralization of organic phosphorous and also as a result of the reduction of iron oxides to which phosphate is adsorbed. Among the inorganic forms, the major contribution towards total phosphorous pool was from calcium bound phosphorous. Sedimentary pH was not found to be a decisive factor in the distributional features of phosphorous forms in the surficial stations as well as in the core profile. In this study, organic carbon displayed co-variability with silty ...

Geochemical characteristics of surficial sediments in the Panangad region of Cochin estuary, the largest brackish-water humid ecosystem in the south-west coast of India, were analysed. Temporal variations in nutrient stoichiometry, seasonal characteristics of redox elements Fe and S, and the phosphorus geochemistry were employed for the purpose. The stoichiometric analysis pointed towards autochthonous origin of organic matter, possibility of nitrogen limitation, and allochthonous modification of redox conditions. Seasonal variations were not statistically significant for all the geochemical parameters, whereas significant spatial variations were observed with lower values at sandy stations, suggesting that the texture of the sediments is the main factor influencing the sediment geochemistry. Significant inter-relations between the geochemical parameters also suggest a common control mechanism. Based on these geochemical characteristics, the study region can be effectively categorized into two distinct zo...

Temporal and spatial variations of heavy metals in the Cochin estuary and its adjacent coastline during three seasons were studied to investigate the impact of anthropogenic heavy metal pollution. Total organic carbon, sand, silt, clay and 10 metals (Cd, Pb, Cr, Ni, Co, Cu, Zn, Mn, Mg and Fe) in the surface sediments were analysed. Multivariate statistical analyses like canonical correspondence analysis, principal component analysis and cluster analysis were used for source identification, integration of geochemical data and clustering of stations based on similarities. Enrichment factor, contamination factor and geoaccumulation index were used to assess the contamination level. From the study, it can be understood that estuary and coast are highly polluted especially with Cd, Zn, Pb and Ni. Anthropogenic influence of heavy metals was evidenced from both the principal component analysis and cluster analysis. Finer fractions (mud) of the sediment and the associated Fe oxy hydroxides might be playing major role in the transport of heavy metals in the system. Very high enrichment factor value observed suggested high anthropogenic pressure in the study area. All the stations in the northern part of the estuary showed very high enrichment factors indicating heavy load of Zn and Cd in this area which might have reached from the industrial area lying to the north side of the Cochin estuary. Pollution indices suggested that both the estuary and its adjacent coast were showing low contamination with respect to Cr, Mg, Mn and Fe; all other metals were causing low to extremely high levels of pollution in the study area.

The study area, Kuttanad Waters is a part of the Cochin estuarine system on the west coast of India. Kuttanad is well known for its agricultural activity and so the major contribution to the inorganic ions of nitrogen will be from fertilisers applied in agriculture. Based on observed salinity the stations have been divided into three zones. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. The chemical speciation scheme applied here distinguishes three forms of ammoniacal nitrogen species: exchangeable, fixed, and organic ammoniacal nitrogen. No significant trends were observed in the seasonal distribution of total, exchangeable, fixed and organic nitrogen. A significant concentration of exchangeable ammonia was observed in the sediment due to their predominantly reducing environment, which restricts nitrification. High NH4-N concentrations in the pore waters, along with the sedimentary composition leads to a significantly high quantity of fixed NH4-N....

Seasonal changes in the concentration of nutrients and various organic compounds were studied in the waters surrounding mangroves and in the marshy areas of mangroves. Higher amounts of nutrients and organic compounds were observed during low tide. This is due to the remineralisation of plant detritus in this area. High concentration of carbohydrates, proteins, chlorophyll and phosphate were observed during monsoon, which can be attributed to the leaching of plant detritus as well as the land run-off. During pre-monsoon and post-monsoon high tannin and lignin concentration was noted. A 24-hour sampling was also done to study the tidal impact on the concentrations of various organic compounds and nutrients in this ecosystem. Even though a tidal impact was observed, a clear picture was not reported in this study.

The fertility of the coastal and estuarine waters is of great concern because of its influence on the productivity of these waters. Seasonal variations in the distribution of organic carbon, total nitrogen and total phosphorus in the sediments of Kuttanad Waters, a part of the tropical Cochin Estuary on the south west coast of India, are examined to identify the contribution of sediments to the fertility of the aquatic systems. The adjoining region has considerable agricultural activity. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. Organic carbon, total phosphorus and total nitrogen were higher in the fresh water zones and lower in the estuarine zones. Total phosphorus and organic carbon showed the lowest values during monsoon periods. No significant trends were observed in the seasonal distributions of total nitrogen. Ratios of C/N, C/P and N/P, and the phosphorus and nitrogen content indicate significant modification in the character of the organic matter. Substantial amounts of the organic matter can contribute to reducing conditions and modify diagenetic processes.