Etiologies, observations and reporting of estuarine finfish lesions.

Lesions in estuarine finfish are associated with a variety of organisms including parasites and bacterial, viral, and fungal infectious agents. In addition, trauma, suboptimal water quality, and other abiotic stress factors may result in the loss of homeostasis. We have observed solitary ulcerative lesions on menhaden sampled from the Chesapeake Bay, Maryland, the Pimlico River, North Carolina, and the St. Johns River, Florida. Histologically, the lesions demonstrated a marked chronic inflammatory infiltrate and granulomas in response to fungal hyphae throughout large areas of exposed necrotic muscle. Gram-negative rod-shaped bacteria were also observed in the lesions, a common finding in ulcers of aquatic organisms. Similar observations in menhaden and other species have been described previously in the literature as ulcerative mycosis, mycotic granulomatosis, red spot disease, and epizootic ulcerative syndrome. Despite the many different known causes of fish lesions, the popular press and the scientific literature have recently emphasized Pfiesteria piscicida and other Pfiesteria-like dinoflagellates (and their bioactive compounds) as the primary causative agent for finfish lesions, particularly mycotic granulomatous ulcers in Atlantic menhaden. While some laboratory data suggest that Pfiesteria may play a role in field-observed lesions, much more cause-and-effect evidence is needed to determine the importance of other risk factors, both alone or and in combination with Pfiesteria. In order to better understand the etiology of lesion initiation and progression in estuarine finfish, accurate assessments of environmental conditions collected on appropriate temporal and spatial scales, and fish morphological indicators consistent with gross and histological pathologic terminology, should be used for reporting fish lesion observations and kills. Further, this outlook will help to avoid bias and may foster a broader perspective for examining the health of estuarine systems in general.     

Petrogenesis of municipal solid waste combustion bottom ash

A petrographic study was conducted on a suite of bottom ash particles from 3 different modern municipal solid waste combustors. The object of the study was to evaluate the mineralogical characteristics and formation process of the bottom ash by using standard geological techniques of light microscopy, electron microscopy, and X-ray microanalysis. This information was subsequently used to model the bottom ash petrogenesis based upon an examination of the mineralogy, melt structure, and composition of the ash.Bottom ash can be divided into two major groups: 1) refractory waste products and 2) melt products. The refractory waste products consist largely of rock and mineral fragments, various waste metals, and unmelted glass shards. The melt products consist of two distinct glasses: 1) isotropic glass, and 2) opaque glass. Complex silicate minerals are precipitated from and are abundant in the isotropic glass whereas both metal oxide and silicate minerals are precipitated from the opaque glass.The isotropic and opaque glasses formed simultaneously in different locations on the combustor grate. The contrast in melting (liquidus) temperatures shown by these glasses suggests that the isotropic melts were produced at localized hot spots (1500°C to 1650°C) and the opaque melts formed at cold spots (1150°C to 1400°C) on the grate. This could be the result of heterogeneous distribution of combustible municipal solid waste on the grate or from localized hot spots where air is introduced through the grates. In some instances the two glasses then had the opportunity to variably mix with each other. Fe-oxides represent waste metal fragments that were assimilated by melting and later recrystallized.Bottom ash is produced via a co-mingled two melt system that forms melilite-bearing, alkaline, volcanic-like rocks. The great similarity of the bottom ash residues between these 3 different MSW combustors suggests that, despite variable combustor designs and heterogeneous waste feed, high temperature combustion of MSW produces bottom ash of fairly uniform composition and structure that formed via the petrogenetic process described above. Alterations to the combustion process or implementations of secondary treatment technologies may render the bottom ash residue into a more environmentally stable material better suited for aggregate or long term secure disposal in landfills.     

Geological and hydrogeological assessment of the Brito Formation: Municipio de Tola,Nicaragua

Hydrogeology Journal - There are sparse hydrogeological data and insufficient hydrogeological knowledge in many areas of the world reliant on groundwater. Nicaragua’s Pacific coast is one...