The objective of this work was to analyze the potential of Rhizophora mangle as a bioindicator of seven heavy metals, Fe, Cu, Zn, Mn, Ni, Cr, and Cd, in the mangrove sediments of the Navachiste lagoon complex (NAV). The concentration of trace metals (TM) in sediments and tis-sues (leaf, stembark, and root of R. mangle) were determined by digestion with nitric acid (HNO3), whereas the metal absorbance was measured by atomic absorption spectrophotometry with an air-acetylene flame. The enrichment factor, the bioavailable fraction, the seasonal varia-tion of heavy metal concentrations and their correlation with those determined in R. mangle tissues were assessed. Metal concentrations found in sediments were as following: Fe>Mn>Zn>Cr>Ni>Cu>Cd, and for tissues: Mn>Fe>Zn>Cu>Cr>Ni>Cd, and regarding the roots, the findings were as following: Fe>Mn>Zn>Cu>Cr>Ni>Cd. The highest trace metal concentra-tions were correlated with silt, clay, and organic matter in sediments with basic pH. The highest salinities were found adjacent to R. mangle trees. Of all the trace metals analyzed, there was only a positive linear regression between the bioavailability of Mn in the sediment with the concen-tration of Mn in leaf tissue consistently throughout the year. The Cu bioavailability in the sedi-ment showed similar positive linear regressions except for winter, where it did not show this pattern. These results suggest that the concentrations of Mn and Cu in the R. mangle leaf could be a potential bioindicator of environmental exposure to anthropogenic sources of contamination by these trace metals in sediments

Unplanned urbanisation and industrialisation have severely degraded natural ecosystems, particularly wetlands. The Ganges-Brahmaputra Basin support 630 million inhabitants; yet continue to be altered rapidly, jeopardizing the region’s social and ecological integrity. By conducting qualitative interviews and participant observation in a wetland dependent village located in the Lower Gangetic Floodplains we investigated how degrading wetlands in sub-urban landscapes were affecting socio-ecological systems. Not only did the wetlands provide livelihood options, mainly fishing and farming, but also provided prestige and autonomy. Vulnerable sections of the society across class, age and gender were solely dependent on the wetland. In absence of political will to safeguard wetland health, industries emerged by altering wetlands, which hampered local community’s livelihood and lifestyle. Further, our study demonstrated that local ecological knowledge could provide qualitative baseline information for fast-tracking identification of important wetlands and creating inventories to initiate wetland conservation and management. Finally, we recommend local governance structures should be strongly tied to international or national wetland policies so that wetland functions along with human health and well-being could be sustained. We strongly advocate that contradictions in policies be resolved to strengthen efforts to conserve wetlands which provide resilience to marginal communities in the face of calamities.

Liquefaction risk assessment is critical for the safety and economics of structures. As the soil strata of Ramsar area in north Iran is mostly composed of poorly graded clean sand and the ground water table is found at shallow depths, it is highly susceptible to liquefaction. In this study, a series of isotropic and anisotropic consolidated undrained triaxial tests are performed on reconstituted specimens of Ramsar sand to identify the liquefaction potential of the area. The specimens are consolidated isotropically to simulate the level ground condition, and anisotropically to simulate the soil condition on a slope and/ or under a structure. The various states of soil behavior are studied by preparing specimens at different initial relative densities and applying different levels of effective stress. The critical state soil mechanics approach for identifying the liquefaction susceptibility is adopted and the observed phenomena are further explained in relation to the micro-mechanical behavior. As only four among the 27 conducted tests did not exhibit liquefactive behavior, Ramsar sand can be qualified as strongly susceptible to liquefaction. Furthermore, it is observed that the pore pressure ratio is a good indication of the liquefaction susceptibility