Soil Acidification, Mineral Neoformation and Heavy Metal Contamination Driven by Weathering of Sulphide Wastes in a Ramsar Wetland

Past waste disposal practices have left large volumes of sulphidic material stockpiled in a Ramsar wetland site on the Atlantic coast of southwestern Spain, leading to severe land degradation. With the aim of addressing this legacy issue, soil core samples were collected along two transects extending from the abandoned stockpiles to the adjacent marshland and subjected to XRD, SEM-EDS, ICP-OES and ICP-MS analyses. Sulphide oxidation has been shown to be a major driver of acid generation and metal leaching into the environment. The marsh soil receiving acid discharges from the sulphide wastes contains elevated levels (in mg kg−1) of Pb (up to 9838), As (up to 1538), Zn (up to 1486), Cu (up to 705), Sb (up to 225) and Tl (up to 13), which are retained both in relatively insoluble secondary minerals (mainly metal sulphates and oxides) and in easily soluble hydrated salts that serve as a transitory pool of acidity and available metals. By using a number of enrichment calculation methods that relate the metal concentrations in soil and their baseline concentrations and regulatory thresholds, there is enough evidence to conclude that these pollutants may pose an unacceptable risk to human and ecological receptors.

A report of Siwalik forest around Letang Raja-Rani wetland, Morang, eastern Nepal

Species composition, phytosociological status and soil characteristics of Siwalik forest occurring around Raja-Rani wetland, Letang municipality, eastern Nepal was studied. A total of 47 tree species belonging to 40 genera and 26 families were reported. Dominant and co-dominant trees were Shorea robusta (IVI=133.4) and Schima wallichii (IVI=70.6), respectively. In the forest total tree density, basal cover area, seedling density, fallen dead density and dead standing density were 378.4 trees ha-1, 163.7 m2 ha-1, 105250 individual ha-1, 4 trees ha-1 and 1.6 trees ha-1, respectively. Irregular girth class distribution and high stump density (136.8 tree ha-1) denote disturbance. Soil physicochemical characteristics were: acidic soil (pH 4.8), moisture (12.5%), water holding capacity (50.05%), bulk density (1.17 g cm-3), porosity (0.55%), humus (8.6%), organic carbon (0.52%), nitrogen (0.1%), phosphorus (33 kg ha-1), and potassium (300 kg ha-1). Regulating human encroachment to ensure natural regeneration of species to maintain the viability of the Letang Raja-Rani wetland site and integrity of the local ecosystem is strongly recommended.

Bryophytes as key indicators of ecosystem function and structure of northern peatlands

Bryophytes play a number of important roles in the functioning and structure of northern peatlands where they form the ground layer of fens and bogs. Sphagnum, dominant in bogs and poor fens, and brown mosses, dominant in rich fens, make up a large percentage of the organic matter that is stored as deep deposits of peat. In this paper we review the mechanisms of resistance to decay in these two moss groups. We then document a case study of a rich fen dominated mostly by Hamatocaulis vernicosus, that has remained stable for over 8000 calendar years. At this site, we use macrofossil abundances, including bryophyte habitat positions on water level and chemistry gradients, to infer past environmental conditions. Lastly, we provide a new ecohydrologic framework for wetland classes centered on bryophyte abundances across water level, nutrient, and salinity gradients and argue that bryophyte species are among the most significant indicators for classifying wetland site-types.

Revealing of Socio-Economic Sustainable Livelihood importance of Rudrasagar lake of Tripura, India

Rudrasagar is a natural waterlogged wetland, also this wetland known as the Ramsar site since 2005. This wetland site is historically as well as ecologically important for the nearby inhabitants. There is an agency namely, Rudrasagar Udvastu Fisherman Samabai Samity Ltd. (RUFSS) manages this wetland activity who are directly dependent and sustains themselves. Pisciculture and agriculture are the main occupations in the local community. This is an integral part of inhabitants; it is not only important economically but socially as well as ecologically. Rudrasagar Lake has 240 hectors according to the Melaghar revenue office. The Rudrasagar lake depth is less in the dry season as well as high in the rainy season. Therefore, the inhabitants are mostly dependent on this lake for their sustainable livelihood. Because of these activities, there are presumption about the degrading of the lake's ecological quality. For the purpose of this study six villages namely, Chandanmura, Rajendranagar, Latamura, Kemtali, Baidermura, and Rangamur took as a sample. With the notion in mind of sustainable livelihood, this research will find the socio-economic importance of the Rudrasagar lake and its legal safeguards.

Microbial Diversity and Mercury Methylation Activity in Periphytic Biofilms at a Run-of-River Hydroelectric Dam and Constructed Wetlands

ABSTRACT Periphytic biofilms have the potential to greatly influence the microbial production of the neurotoxicant monomethylmercury in freshwaters although few studies have simultaneously assessed periphyton mercury methylation and demethylation rates and the microbial communities associated with these transformations. We performed a field study on periphyton from a river affected by run-of-river power plants and artificial wetlands in a boreal landscape (Québec, Canada). In situ incubations were performed on three sites using environmental concentrations of isotopically enriched monomethylmercury (MM198Hg) and inorganic mercury (200Hg) for demethylation and methylation rate measurements. Periphytic microbial communities were investigated through 16S rRNA gene analyses and metagenomic screenings for the hgcA gene, involved in mercury methylation. Positive mercury methylation rates ([5.9 ± 3.4] × 10−3 day−1) were observed only in the wetlands, and demethylation rates averaged 1.78 ± 0.21 day−1 for the three studied sites. The 16S rRNA gene analyses revealed Proteobacteria as the most abundant phylum across all sites (36.3% ± 1.4%), from which families associated with mercury methylation were mostly found in the wetland site. Metagenome screening for HgcA identified 24 different hgcA sequences in the constructed wetland site only, associated with 8 known families, where the iron-reducing Geobacteraceae were the most abundant. This work brings new information on mercury methylation in periphyton from habitats of impacted rivers, associating it mostly with putative iron-reducing bacteria. IMPORTANCE Monomethylmercury (MMHg) is a biomagnifiable neurotoxin of global concern with risks to human health mostly associated with fish consumption. Hydroelectric reservoirs are known to be sources of MMHg many years after their impoundment. Little is known, however, on run-of-river dams flooding smaller terrestrial areas, although their numbers are expected to increase considerably worldwide in decades to come. Production of MMHg is associated mostly with anaerobic processes, but Hg methylation has been shown to occur in periphytic biofilms located in oxic zones of the water column. Therefore, in this study, we investigated in situ production of MMHg by periphytic communities in habitats impacted by the construction of a run-of-river dam by combining transformation rate measurements with genomic approaches targeting hgcAB genes, responsible for mercury methylation. These results provide extended knowledge on mercury methylators in river ecosystems impacted by run-of-river dams in temperate habitats.

LAKE SETTLEMENTS OF THE UPPER VOLGA REGION IN THE 7—6th mil. CAL BC: ARCHAEOLOGICAL AND PALAEOECOLOGICAL CONTEXT OF THE FIRST POTTERY’ «INVASION» (ZAMOSTJE 2)

In the Middle Holocene, favorable living conditions were formed environmental on the territory of the modern Upper Volga River, which, after the retreat of the latest glacier, abounded with a branched system of feeders. They contributed to the economic stability driven by hunting for elk and beaver, waterfowl and marsh birds, as well as intensive fishing. In the recent decades, it was considered proven that ceramics were perceived by the native population, and the Early Neolithic, thus, was developed on a local basis. The new data accumulated in recent years makes it possible to bring up this topic again. Natural, economic and cultural changes during the period from the end of the 7th to the beginning of the 6th millennium cal BC are considered on the example of the well-known multi-layer wetland site Zamostje 2, with preserved wooden fishing structures and a large number of bone and antler artefacts. The period of sharp climatic changes, known as the 8200 Cold Event, synchronous with the upper Mesolithic layer, influenced the site landscape, but, as it seems, did not affect the lifestyle of the local population. The comparison between the two main archaeological layers of the lake settlement — the Late Mesolithic Upper layer (LM UL) and the Early Neolithic (EN), represented by the Upper Volga culture (UVc), shows both clear traces of continuity, primarily in the structure of the economy and production toolkits as well as new cultural influences reflected in the types of projectile hunting weapons and fishing gear. The function of the Early Neolithic pots, reconstructed on the basis of lipid analysis, also indicates the preservation of the comprehensive Mesolithic diet.