Allometry, biomass, and productivity of mangrove forests: A review

A review of traffic-related air pollution exposure assessment studies in the developing world.

Besides water vapour, greenhouse gases CO2, CH4, O3 and N2O contribute ~60%, 20%, 10% and 6% to global warming, respectively; minor contribution is made by chlorofluorocarbons and volatile organic compounds (VOC). We present CO2, CH4 and N2O fluxes from natural and relatively unmanaged soil–plant ecosystems (the ecosystems minimally disturbed by direct human or human-induced activities). All natural ecosystems are net sinks for CO2, although tundra and wetlands (including peatlands) are large sources of CH4, whereas significant N2O emissions occur mainly from tropical and temperate forests. Most natural ecosystems decrease net global warming potential (GWP) from –0.03 ± 0.35 t CO2-e ha–1 y–1 (tropical forests) to –0.90 ± 0.42 t CO2-e ha–1 y–1 (temperate forests) and –1.18 ± 0.44 t CO2-e ha–1 y–1 (boreal forests), mostly as CO2 sinks in phytobiomass, microbial biomass and soil C. But net GWP contributions from wetlands are very large, which is primarily due to CH4 emissions. Although the tropical forest system provides a large carbon sink, the negligible capacity of tropical forests to reduce GWP is entirely due to N2O emissions, possibly from rapid N mineralisation under favourable temperature and moisture conditions. It is estimated that the natural ecosystems reduce the net atmospheric greenhouse gas (GHG) emissions by 3.55 ± 0.44 Gt CO2-e y–1 or ~0.5 ppmv CO2-e y–1, hence, the significant role of natural and relatively unmanaged ecosystems in slowing global warming and climate change. However, the impact of increasing N deposition on natural ecosystems is poorly understood, and further understanding is required regarding the use of drainage as a management tool, to reduce CH4 emissions from wetlands and to increase GHG sink from the restoration of degraded lands, including saline and sodic soils. Data on GHG fluxes from natural and relatively unmanaged ecosystems are further compounded by large spatial and temporal heterogeneity, limited sensitivity of current instruments, few and poor global distribution of monitoring sites and limited capacity of models that could integrate GHG fluxes across ecosystems, atmosphere and oceans and include feedbacks from biophysical variables governing these fluxes.

TURNER REVIEW No. 18. Greenhouse gas fluxes from natural ecosystems

Air pollution trends over Indian megacities and their local-to-global implications

Humic acids (HAs) isolated from sewage sludge (SS) and control and SS-amended soils were characterized by fluorescence spectroscopy. The main feature of fluorescence spectra was a broad band with the maximum centered at excitation/emission wavelengths that were much shorter for SS-HA (340/438 nm) than for any soil HA (440/510 nm). Titration with Cu(II), Zn(II), Cd(II), and Pb(II) ions decreased fluorescence intensities of HAs. Titration data were fitted to a single-site fluorescence quenching model, and metal ion complexing capacities of each HA sample and stability constants of metal ion−HA complexes were calculated. The binding capacities of HAs and strengths of metal ion−HA complexes followed the order Pb(II) > Cu(II) > Cd(II) > Zn(II). With respect to the control soil HA, SS-HA, which showed the smallest contents of acidic functional groups and the lowest humification degree, was characterized by much smaller binding capacities and stability constants. The binding capacities and affinities of SS-amend...

Molecular and Quantitative Analysis of Metal Ion Binding to Humic Acids from Sewage Sludge and Sludge-Amended Soils by Fluorescence Spectroscopy

Impact of Sundarban mangrove biosphere on the carbon dioxide and methane mixing ratios at the NE Coast of Bay of Bengal, India

Ground-level concentration of nitrogen oxides (NOx) at some traffic intersection points in Calcutta

Humic (HA) and fulvic (FA) acids isolated from mangrove sediments of Sundarban, the largest delta on earth in the estuarine phase of the river Ganges, were studied and attempts were made to characterize their binding sites by quenching of Synchronous fluorescence (SyF) bands with Fe (III) and Cu (II) A modified Stern-Volmer relationship applicable for static quenching was applied for the determination of conditional stability constants and the data were compared with those determined by potentiometric titration In the excited state HA and FA showed different acidity constant compared to the ground state Values of the conditional stability constant (log Kc) for Fe (III) and Cu (II) indicated that binding sites were bidentate in nature FA were better chelators than the HA fractions High energy binding sites of both FA & HA were occupied by Fe(III) and the low energy binding sites, mainly responsible for mobilization and immobilization of metal, were occupied by Cu(II)

Interactions of Cu (II) and Fe (III) with mangal humic substances studied by synchronous fluorescence spectroscopy and potentiometric titration

On the nature and structure of ‘niobic acid’. Part IV: Formation of sulphatoniobates(V) and the properties of isopolyniobic acid produced therefrom

Steatite bodies were developed, using both pure and impure variety of Jaipur talcs. Bonding agents used were starch and wax. The bodies were fired in electric kiln using magnesite brick and magnesite powder as kiln setting materials. The bodies were tested for shrinkage, absorption and electrical properties like power factor, dielectric constant and loss factor. © 1965, Taylor and Francis Group, LLC

B. K. Sen

Papers

Impact of Sundarban mangrove biosphere on the carbon dioxide and methane mixing ratios at the NE Coast of Bay of Bengal, India

Ground-level concentration of nitrogen oxides (NOx) at some traffic intersection points in Calcutta

Interactions of Cu (II) and Fe (III) with mangal humic substances studied by synchronous fluorescence spectroscopy and potentiometric titration

On the nature and structure of ‘niobic acid’. Part IV: Formation of sulphatoniobates(V) and the properties of isopolyniobic acid produced therefrom

Some Problems Connected with the Manufacture of Steatites