Application of the comet and micronucleus assays to butterfish (Pholis gunnellus) erythrocytes from the Firth of Forth, Scotland.

This report describes an investigation of genotoxic effects in an inter-tidal fish species sampled along a pollution gradient in the Firth of Forth, Scotland, UK. The comet assay is an electrophoretic technique for measuring DNA breakage in nuclei from individual cells and has only recently been applied to field investigations of genotoxicity. The measurement of nuclear anomalies (NA), such as the presence of micronuclei (MN) and 'lobes', has been successfully utilised in many field studies of genotoxic effects of contaminated sediments. These two techniques were applied to nucleated red blood cells (RBC) from the butterfish, Pholis gunnellus. The comet assay was adapted and validated for use in this species. Fish were sampled from the inner Firth of Forth, which has a legacy of industrial contamination and the outer Firth of Forth which is comparatively clean. The analysis of DNA strand breakage using this technique did not reveal any significant differences between animals sampled from inner and outer zones of the Firth. In contrast, MN and NA frequencies were elevated in the inner polluted zone of the Firth compared to the outer zone. This study suggests: (1) there are genotoxic effects associated with contaminants in the inner Firth of Forth, and (2) the comet assay may not be a suitable genotoxicity biomarker in fish.     

WATERSHED SCALING EFFECT ON BASE FLOW NITRATE,VALLEY AND RIDGE PHYSIOGRAPHIC PROVINCE1

ABSTRACT: A study of stream base flow and NO₃‐N concentration was conducted simultaneously in 51 subwatersheds within the 116‐square‐kilometer watershed of East Mahantango Creek near Klingerstown, Pennsylvania. The study was designed to test whether measurable results of processes and observations within the smaller watersheds were similar to or transferable to a larger scale. Ancillary data on land use were available for the small and large watersheds. Although the source of land‐use data was different for the small and large watersheds, comparisons showed that the differences in the two land‐use data sources were minimal. A land use‐based water‐quality model developed for the small‐scale 7.3‐square‐kilometer watershed for a previous study accurately predicted NO₃‐N concentrations from sampling in the same watershed. The water‐quality model was modified and, using the imagery‐based land use, was found to accurately predict NO₃‐N concentrations in the subwatersheds of the large‐scale 116‐square‐kilometer watershed as well. Because the model accurately predicts NO₃‐N concentrations at small and large scales, it is likely that in second‐order streams and higher, discharge of water and NO₃‐N is dominated by flow from smaller first‐order streams, and the contribution of ground‐water discharge to higher order streams is minimal at the large scale.     

MERCURY IN WATER AND SEDIMENT OF STEAMBOAT CREEK,NEVADA: IMPLICATIONS FOR STREAM RESTORATION1

ABSTRACT: The objective of this study was to characterize the sources, concentrations, and distribution of total and methylmer‐cury in water, and channel and bank sediments of Steamboat Creek, Nevada. This information was needed to begin to assess the potential impacts of stream restoration on mercury pollution in this tributary to the Truckee River. The Truckee River flows into Pyramid Lake, a terminal water body home to one endangered and one threatened fish species, where stable pollutants will accumulate over time. Mercury in Steamboat Creek was originally derived from its headwaters, Washoe Lake, where several gold and silver mills that utilized mercury were located. In the 100 plus years since ore processing occurred, mercury‐laden alluvium has been deposited in the stream channel and on streambanks where it is available for remobilization. Total mercury concentrations measured in unfiltered water from the creek ranged from 82 to 419 ng/L, with greater than 90 percent of this mercury being particle‐bound (> 0.45 (m). Mercury in sediments ranged from 0.26 to 10.2 μg/g. Methylmercury concentrations in sediments of Steamboat Creek were highest in wetlands, lower in the stream channel, and still lower in streambank settings. Methylmercury concentrations in water were 0.63 to 1.4 ng/L. A streambank restoration plan, which includes alterations to channel geometry and wetland creation or expansion, has been initiated for the creek. Data developed indicate that streambank stabilization could reduce the mercury loading to the Creek and that wetland construction could exacerbate methylmercury production.     

Extruded Cornstarch-Glycerol-Polyvinyl Alcohol Blends: Mechanical Properties, Morphology, and Biodegradability

Elongation properties of extruded cornstarch were improved by blending with glycerol. Further blending of starch-glycerol with polyvinyl alcohol (PVOH) resulted in significant improvements in both tensile strength (TS) and elongation at break. Samples of starch-glycerol without PVOH equilibrated at 50% relative humidity had a TS of 1.8 MPa and elongation of 113%, whereas those containing PVOH had a TS and elongation of 4 MPa and 150%, respectively. Dynamic mechanical analysis (DMA) of starch-glycerol-PVOH blends showed that decreases in glass transition temperatures (T _g values) were proportional to glycerol content. Scanning electron microscopy (SEM) of fractured surfaces revealed numerous cracks in starch-glycerol (80:20) samples. Cracks were absent in starch-glycerol (70:30) samples. In both blends, many starch granules were exposed at the surface. No exposed starch granules were visible in blends with added PVOH. Starch-glycerol samples incubated in compost lost up to 70% of their dry weight within 22 days. Addition of PVOH lowered both the rate and extent of biodegradation.     

The natural production of organobromine compounds

Organobromine chemicals are produced naturally by an array of biological and other chemical processes in our environment. Some of these compounds are identical to man-made organobromine compounds, such as methyl bromide, bromoform, and bromophenols, but many others are entirely new moleclar entities, often possessing extraordinary and important biological properties. Although only a few natural organobromine compounds had been discovered up to 1968, this number as of early 1999 is more than 1,600, and new examples are being discovered continually. Organobromine compounds are produced naturally by marine creatures (sponges, corals, sea slugs, tunicates, sea fans) and seaweed, plants, fungi, lichen, algae, bacteria, microbes, and some mammals. Many of these organobromine compounds are used in chemical defense, to facilitate food gathering, or as hormones.     

Small island developing states and sustainable development of ocean resources

Because of their economic and environmental vulnerability, small island developing states (SIDS) have peculiar developmental problems that severely affect their ability to implement the measures necessary for attaining sustainable development as recommended in UNCED's Agenda 21. Although this has been recognised by the Commission on Sustainable Development (CSD), and although there has been international acceptance of a SIDS Programme of Action (POA), SIDS have not been the focus of adequate attention by international and donor agencies. As a result, progress toward implementing the POA has been disappointing. This study examines the question of how sustainable management and development of ocean resources can contribute significantly to the achievement of the objectives of the SIDS POA.     

A numerical model for transient-hysteretic flow and solute transport in unsaturated porous media

A two-dimensional flow and transport model was developed for simulating transient water flow and nonreactive solute transport in heterogeneous, unsaturated porous media containing air and water. The model is composed of a unique combination of robust and accurate numerical algorithms for solving the Richards', Darcy flux, and advection-dispersion equations. The mixed form of Richards' equation is solved using a finite-element formulation and a modified Picard iteration scheme. Mass lumping is employed to improve solution convergence and stability behavior. The flow algorithm accounts for hysteresis in the pressure head-water content relationship. Darcy fluxes are approximated with a Galerkin and Petrov-Galerkin finite-element method developed for random heterogeneous porous media. The transport equation is solved using an Eulerian-Lagrangian method. A multi-step, fourth-order Runge-Kutta, reverse particle tracking technique and a quadratic-linear interpolation scheme are shown to be superior for determining the advective concentration. A Galerkin finite-element method is used for approximating the dispersive flux. The unsaturated flow and transport model was applied to a variety of rigorous problems and was found to produce accurate, mass-conserving solutions when compared to analytical solutions and published numerical results.     

Can a key boreal Calanus copepod species now complete its life-cycle in the Arctic? Evidence and implications for Arctic food-webs

The changing Arctic environment is affecting zooplankton that support its abundant wildlife. We examined how these changes are influencing a key zooplankton species, Calanus finmarchicus, principally found in the North Atlantic but expatriated to the Arctic. Close to the ice-edge in the Fram Strait, we identified areas that, since the 1980s, are increasingly favourable to C. finmarchicus. Field-sampling revealed part of the population there to be capable of amassing enough reserves to overwinter. Early developmental stages were also present in early summer, suggesting successful local recruitment. This extension to suitable C. finmarchicus habitat is most likely facilitated by the long-term retreat of the ice-edge, allowing phytoplankton to bloom earlier and for longer and through higher temperatures increasing copepod developmental rates. The increased capacity for this species to complete its life-cycle and prosper in the Fram Strait can change community structure, with large consequences to regional food-webs.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01667-y.     

Women farmers’ perceived indices of occurrence and severity of observed climate extremes in rural Savannah,Ghana

Environment, Development and Sustainability - Climate extremes over the years have been a major concern for the globalized world. The hardest hit from these climate extremes are women farmers with...