Mercury speciation in the Scheldt Estuary

Surface waters of the Scheldt Estuary were sampled on various occasions between 1991 and 1994. Longitudinal particulate Hg (PM) concentrations ranged from 0.4 – 1.7 μgHg/g and are essentially controlled by physical mixing of polluted fluvial particulates with relatively unpolluted marine particulates. Total dissolved mercury (TDM)concentrations ranged from 0.5 to 5.2 ng/L and are strongly influenced by removal and mobilization processes in the upper estuary, while in the lower estuary mixing processes cause a progressive decrease in TDM towards the mouth. Speciation studies showed that dissolved Hg is predominantly bound to strong complexing ligands (organic substances) in the upper estuary, but this fraction decreases with increasing salinity. In June 1993, however, the reactive mercury fraction was also high in the upper estuary. Model calculations showed that a conditional stability constant for Hg- humic acid interactions of 10¹⁹ was a good estimate for the Scheldt estuary. Dissolved methylmercury was analyzed on three occasions. Significant seasonal variations were observed with concentrations ranging from 11 to 120 pg/L in the winter and 80 to 400 pg/L in summer. Supersaturation of Hg° is observed throughout the whole estuary resulting in an estimated evasion flux of 140–1400 ng/m² day.     

Urban green spaces analysis for development planning in Colombo,Sri Lanka,utilizing THEOS satellite imagery – A remote sensing and GIS approach

Upon conclusion of the 30 years of civil conflict, Sri Lanka has entered into a new era of development. The beautification project of Colombo, Sri Lanka's commercial capital, can be considered as one of the most important projects among urban planning and restoration endeavours implemented throughout the island. In such urban development endeavour, green spaces planning play a crucial role in improving the environmental quality and standard of living of the residents. The objective of this study is to analyse the environmental quality in Colombo city based on green spaces and to provide appropriate recommendations to raise the environmental quality to international standards.In this study, green space areas were extracted from Thailand Earth Observation System (THEOS) satellite imagery using Normalized Difference Vegetation Index (NDVI). Extracted green space areas were further analysed quantitatively with air quality indicators and population density utilizing deductive indexing method at Grama Niladhari (GN) administrative division level to identify correlations of these factors. An environmental criticality map based on population density and percentage green spaces has been constructed to identify the areas with high criticality. The study revealed that 24% of the entire Colombo Municipal Council (CMC) area consists of green spaces. This study also revealed that 34 GN divisions out of 55 lack the minimum per capita green space recommended by World Health Organization for healthy living. Recommendations are presented regarding regions where new green spaces should be established to enhance the environmental standard of living up to international standards.     

Reprint of 'Are forest researchers only scientists? Case studies on the roles of researchers in Japanese and Swedish forest policy processes'

The aim of this study is to clarify the roles of researchers in forest policy development processes. Comparative case studies between Japan and Sweden were conducted. The research–integration–utilisation (RIU) model on scientific knowledge transfer was employed as a framework. Based on the RIU model, ‘scientist’, ‘integrator’, and ‘policy entrepreneur’ were defined as three hypothesised roles of researchers, discussed in conjunction with Pielke's ‘honest broker’ model. It was found that researchers played important roles, both as scientists and integrators in Japan. In Sweden, researchers played only the role of scientist. However, no researchers working as policy entrepreneurs were found in either country. These results indicate that the RIU model could work as a basis for the comparison between countries and the clarification of the roles of researchers in forest policy processes. The case study analysis also specified three additional topics for further discussion: (1) different types of science-based policy advice; (2) the relationship between power allies and consensus building; and (3) the reason why the roles of researchers differ between Japan and Sweden.     

Natural Mercury Levels in Geological Enriched and Geological Active Areas: Case Study of Katun River and Lake Teletskoye,Altai (Siberia)

Natural geological Hg deposits control the Hg levels inthe upper Katun river. Very high levels of total Hg areobserved in the watercolumn (up to 20 ng L^-1) and thesediments (up to 244 μg g^-1) close to the depositarea, but almost normal levels (1.8 ng L^-1 in the watercolumn and 0.14 μg g^-1 in the sediments) are reached60 km downstream of that zone. In general, low dissolvedmethylmercury (MMHg) concentrations were found (0.04–0.05 ngL^-1) due to unfavourable methylation conditions. The MMHgconcentrations in the sediments vary from 23.3 ng g^-1, inthe vicinity of the geological Hg deposits, to 0.17 ng g^-1 60 km downstream.Total Hg levels in Lake Teletskoye (a geological activearea) are slightly increased (1.1–1.8 ng L^-1) compared toLake Baikal and fairly constant alover the Lake, suggestingmultiple sources. High mercury concentrations in springs andsoils coincide with high radon concentrations in the samecompartments as well as high soil exhalation fluxes. Theseresults in combination with the fact that Lake Teletskoye islocated in an active fault zone suggest that the Rn and Hgsources may be fault aligned spring waters and deep seatedgases escaping through open cracks. Methylmercuryconcentrations in the Lake (0.03–0.1 ng L^-1) werecomparable to the concentrations found in Katun river butrelative to the total Hg burden this means a higher percentage.     

Nutrient Removal from Simulated Wastewater Using Canna indica and Schoenoplectus validus in Mono- and Mixed-Culture in Wetland Microcosms

In order to understand the bioaccumulation of mercury in fish in the Iranian coastal waters of the Caspian Sea and the Persian Gulf, different fish species were sampled from both regions in January 2002. Mullet fishes were sampled from the Caspian Sea and six other species from the Persian Gulf: Largetooth flounder, Spotfin flathead, Japanese threadfin bream, Greater lizardfish, Elongate sole and Giant seacatfish. In the Persian Gulf, total Hg concentrations in fish ranged from 0.0123 to 0.0867 mg kg^?1 w.w. (0.0614 to 0.433 mg kg^?1 d.w.). Methylmercury accounts for 64–100% of the total mercury. Highest mercury concentrations were observed in the predatory fish: Giant seacatfish, Threadfin bream and the larger Greater lizardfish caught near Mogham Port. In these species the methylmercury fraction is always higher than 90%. A low methylmercury fraction was only observed in the smallest specimen of flounder and Elongate sole. In the Caspian Sea Hg concentrations in Mullet ranged from 0.0102 to 0.108 mg kg^?1 w.w. The observed concentrations are comparable to those found in other areas of the Persian Gulf as well as in other marine environments and are much lower then the WHO guideline of 0.5 mg kg^?1 w.w.     

Global patterns of diversity in the urban forest: Is there evidence to support the 10/20/30 rule?

Diversity in the urban forest is important as it reduces risks from pests and diseases and from climate change and improves resilience in the supply of ecosystem services. To manage and improve diversity, there has been wide-spread acceptance of the 10/20/30 ‘rule of thumb’ proposed by Santamour, which states that municipal forests should comprise no more than 10% of any particular species, 20% of any one genus or 30% of any single family. While the implementation of targets based on Santamour's rule has contributed to a more diverse and resilient urban forest in many cities, there has been little empirical investigation of actual patterns of diversity occurring globally in different climates and land uses. In this study, we explored diversity and the relative abundance of the most common species, genus and family in 151 urban forest inventories from 108 different cities around the world. Observed patterns showed that relative abundance of the most common taxon was a good predictor of diversity and could be a useful measure of diversity for urban forest managers. Relative abundance of the most common taxon was much higher than the proposed benchmark at the species level, but comparable with proposed benchmarks at the genus and family level. Patterns varied by both climate and land use. Diversity was consistently lower in Continental climates and in streetscapes, and higher in Temperate climates and in urban forests that spanned multiple land uses. Further considerations in setting diversity benchmarks are discussed.     

Landscape perception and recreation needs in urban green space in Fuyang,Hangzhou, China

This study analyzes the landscape characteristics and the residents’ recreational activities in the urban green spaces in Fuyang, Hangzhou, China. It explores the correlation of the desire to be in close proximity to urban green space to engage in recreational activities (the need for recreation) related to residents’ demographic and socio-economic factors: gender, education, monthly income and dwelling location. Residents’ preferences for landscape elements and attributes of urban green space are examined using principal components analysis. In addition, regression analysis identifies that coherence and vegetation are the most relevant factors correlated with perceived overall recreational appropriateness of the three most frequently visited urban parks. The purpose of the study is to attempt to quantify people's recreation needs in urban green space; identify the landscape components in urban green space which can encourage more outdoor visits and/or greater recreational activities; and provide proposals and strategies on planning, management and conservation for recreation-oriented urban green space which will enhance people's enjoyment and wellbeing by improving landscape esthetic quality, recreational and ecological function.     

Linking demand and supply factors in identifying cultural ecosystem services of urban green infrastructures: A review of European studies

Urban green infrastructure provides a number of cultural ecosystem services that are greatly appreciated by the public. In order to benefit from these services, actual contact with the respective ecosystem is often required. Furthermore, the type of services offered depend on the physical characteristics of the ecosystem. We conducted a review of publications dealing with demand or social factors such as user needs, preferences and values as well as spatially explicit supply or physical factors such as amount of green space, (bio)diversity, recreational infrastructure, etc. and linking demand and supply factors together. The aim was to provide an overview of this highly interdisciplinary research, to describe how these linkages are being made and to identify which factors significantly influence dependent variables such as levels of use, activities or health and well-being benefits. Commonly used methods were the combination of questionnaires with either on-site visual recording of elements or GIS data. Links between social and physical data were usually established either by using statistical tools or by overlaying different thematic maps. Compared to the large number of variables assessed in most studies, the significant effects in the end were relatively few, not consistent across the studies and largely dependent on the context they were seen in. Studies focused on aesthetic and recreational services, while spiritual, educational and inspirational services were not considered when creating links to spatially explicit ecological structures. We conclude that an improvement and harmonization of methodologies, cross-country studies and an expansion of this line of research to a wider range of services and more user groups could help clarify relationships and thereby increase applicability for urban management and planning.     

Mercury contamination of the harbour porpoise Phocoena phocoena and other cetaceans from the North Sea and the kattegat

Total Hg levels were determined in 17 harbour porpoises Phocoena phocoena collected in the North Sea and the Kattegat (muscle, liver and kidney), as well as in a sperm whale Physeter macrocephalus, a common dolphin Delphinus delphis and two bottle-nose dolphins Tursiops truncatus collected in Belgium. Juvenile porpoises (total body length less than 140 cm) were characterized by total Hg concentrations increasing with length (t.i. with age) with median values of 3.1 μg g^?1 dw in muscle, 6.2 in liver and 5.7 in kidney, and liver to muscle resp. liver to kidney ratios varying between 1 and 2. In adults, liver concentrations were higher (up to 500 μg g^?1 dw) with liver to muscle and to kidney ratios up to 20. Median McHg concentrations in 5 of the porpoises were 4.0 μg g^?1 dw in muscle and 6.9 in liver. These values did not increase as strongly with length (t.i. with age, at least for juveniles) as total Hg did; as a consequence, the relative McHg levels decreased from 100% in juveniles to 2 or 3 % in the liver of adults. Such results seem to reflect the existence of a slow mineralization phenomenon and storage of inorganic Hg, mainly in the liver.