Sustained viability and profileration of hemocytes from the cultured pharynx of Styela clava

In order to acquire more in-depth information on the site(s) of hemopoiesis in marine animals, we successfully cultured pharyngeal explants of the tunicate Styela clava over a period of 82 d. Transmission electron microscopy of resident hemocytes within explants revealed changes in hemocyte composition. Hemoblast-like cells increased shortly after commencement of the cultures (8.1% at Day 0 increasing to a maximum of 28.7% at Day 7). Autoradiography using ³H-thymidine incorporation confirmed that hemocyte proliferation in pharyngeal explants still continued after 37 d culture. During culture, the migration of many free cells into the medium resulted in sparse, residential hemocytes in the pharyngeal explants. Hemocyte migration increased by up to 4.3x10⁵ cells/explant (max.) at 17 to 24 d, but finally decreased to 4.9x10⁴ cells/explant at 75 to 82 d. Vital neutral-red staining revealed that many emerging cells were not hemocytes such as those found in the normal hemolymph. The continued development of in vitro approaches will strengthen analyses of immune-defense responses in tunicates which, as protochordates, are the immediate invertebrate ancestors of vertebrates.     

Evidence of sulphur and nitrogen deposition signals at the United Kingdom Acid Waters Monitoring Network sites

Some recent studies of trends in sulphate in surface waters have alluded to possible lag effects imposed by catchment soils, resulting in discrepancies between trends in deposition and run-off. To assess the extent of these possible effects in the UK, sulphate concentration data from the United Kingdom Acid Waters Monitoring Network (AWMN) sites are compared with estimates of sulphur deposition at each site. From these data, input-output budgets are computed at an annual time scale. The estimated budgets suggest a close association between catchment sulphur inputs and outputs at an annual scale, with well-balanced annual budgets at most sites, indicative of only minor lag effects. A similar analysis of the AWMN site nitrogen budget shows little evidence of an association between nitrogen inputs and outputs at this time scale.     

ADDITION OF SPURS TO STONE TOE PROTECTION FOR WARMWATER FISH HABITAT REHABILITATION1

ABSTRACT: Longitudinal stone toe is one of the most reliable and economically attractive approaches for stabilizing eroding banks in incised channels. However, aquatic habitat provided by stone toe is inferior to that provided by spur dikes. In order to test a design that combined features of stone toe and spurs, eleven stone spurs were placed perpendicular to 170 m of existing stone toe in Goodwin Creek, Mississippi, and willow posts were planted in the sandbar on the opposite bank. Response was evaluated by monitoring fish and habitats in the treated reach and an adjacent comparison reach (willow post planting and standard toe without spurs) for four years. Furthermore, physical habitats within the treated reach were compared with seven reaches protected with standard toe on a single date three years after construction. Overall results indicated that spur addition resulted in modest increases in baseflow stony bankline, water width and pool habitat availability, but had only local effects on depth. These relatively small changes in physical habitat were exaggerated seasonally by beaver dams that appeared during periods of prolonged low flow in late Summer and Autumn. Physical changes were accompanied by shifts in fish species composition away from a run-dwelling assemblage dominated by large numbers of cyprinids and immature centrarchids toward an assemblage containing fewer and larger centrarchids. Biological responses were at least partially due to the effects of temporary beaver dams.     

A goal interval programming model for resource allocation in a marine environmental protection program

A multidimensional “goal programming” model is developed to aid resource allocation decisions in the U. S. Coast Guard's Marine Environmental Protection (MEP) program. It is then extended to a model of “goal interval programming” (GIP ) type where exact values for the indicated goals, as in ordinary goal programming, are replaced by ranges. Deviations outside these ranges are also accommodated by piecewise linear functions with slopes that vary with distance from the goal intervals. Uses and generalizations are discussed in the context of applications to allocating manhours and planning the activities of the Coast Guard's MEP program.     

Recovery of forest structure and spectral properties after selective logging in lowland Bolivia.

Effective monitoring of selective logging from remotely sensed data requires an understanding of the spatial and temporal thresholds that constrain the utility of those data, as well as the structural and ecological characteristics of forest disturbances that are responsible for those constraints. Here we assess those thresholds and characteristics within the context of selective logging in the Bolivian Amazon. Our study combined field measurements of the spatial and temporal dynamics of felling gaps and skid trails ranging from <1 to 19 months following reduced-impact logging in a forest in lowland Bolivia with remote-sensing measurements from simultaneous monthly ASTER satellite overpasses. A probabilistic spectral mixture model (AutoMCU) was used to derive per-pixel fractional cover estimates of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), and soil. Results were compared with the normalized difference in vegetation index (NDVI). The forest studied had considerably lower basal area and harvest volumes than logged sites in the Brazilian Amazon where similar remote-sensing analyses have been performed. Nonetheless, individual felling-gap area was positively correlated with canopy openness, percentage liana coverage, rates of vegetation regrowth, and height of remnant NPV. Both liana growth and NPV occurred primarily in the crown zone of the felling gap, whereas exposed soil was limited to the trunk zone of the gap. In felling gaps >400 m2, NDVI, and the PV and NPV fractions, were distinguishable from unlogged forest values for up to six months after logging; felling gaps <400 m2 were distinguishable for up to three months after harvest, but we were entirely unable to distinguish skid trails from our analysis of the spectral data.     

Trends in surface water chemistry of acidified UK freshwaters, 1988-2002

Analysis of water chemistry data from 15 years of monitoring at 22 acid-sensitive lakes and streams in the UK reveals coherent national chemical trends indicative of recovery from acidification. Excess sulphate and base cations exhibit significant decline, often accompanied by an increase in an alkalinity-based determination of acid neutralising capacity (AB-ANC) and, at fewer sites, a decline in hydrogen and labile aluminium. Acid neutralising capacity determined by "charge-balance" (CB-ANC) exhibits few trends, possibly due to compound errors associated with its determination. Trend slopes in excess sulphate correlate with those for base cations, hydrogen ion and AB-ANC, with between-site variability linked to catchment hydrology, sea-salt inputs and forestry. Nitrate concentrations have not changed significantly but show high sensitivity to varying climate. Trends in AB-ANC are influenced by significant increases in dissolved organic carbon, the cause of which it is vital to establish before trends in the former can definitively be attributed to decreasing acidic deposition.     

Individualized water source as an indicator of attitudes about water management and conservation in humid regions

Public perceptions about water quantity and water as a common pool resource are understudied in humid regions. As water demand increases, the need to more closely manage water, even in humid areas, will increase, requiring better understanding how people perceive their water supply, how they view paying for water conservation and how water user characteristics influence attitudes. A survey finds correlations between utilizing an individual water source (e.g. well or spring) and attitudes toward water management and conservation. Compared to respondents with a shared water source, those with an individual source believe they are segregated from regional water concerns. They are less willing to pay for water management or conservation measures and less supportive of any government intervention in water management. These results suggest that planners and water managers may face resistance to conservation policies or any policy based on the idea of water as a common pool resource.     

Receptor Oriented Methods of Air Particulate Source Apportionment

Receptor models have evolved rapidly over the past 13 years but have just recently been recognized as a distinct discipline. The general category of receptor models includes both microscopic and chemical methods of apportioning source contributions to ambient air particulates. The number and variations of these methods have grown rapidly over the past few years and include such methods as automated scanning electron microscopy, chemical mass balance and multivariate procedures. These methods as well as hybrid procedures such as target transformation factor analysis, are reviewed and their boundary conditions, strengths, and weaknesses discussed.     

Closing Comments

“Industrial fabric filtration, the sleeping giant, is stirring. It appears that we are about to experience a new period of innovation and development similar to the one that occurred during the 1950’s.” The above remarks by Professor First, as presented in the Symposium, unerscore the renewed interest in filtration as a means for controlling submicron particulate emissions. Bur-chard and others pointed out the significance of fine particulate emissions, especially with regard to health effects and visibility degradation, and Walsh discussed the data required to employ fabric filters appropriately for particulate emission control.     

The reactions of paraquat and divalent metal ions with humic acid: Factors influencing stoichiometry 2

Abstract

Laurentide humic acid has been titrated with paraquat and with selected divalent metal ions. In some cases, the humic acid was spiked with one cation before titration with another one. Several equivalence points were determined for the binding of the divalent cations, including paraquat. Three equivalence points agreed well with values predicted from the acidic properties of the humic acid. Eight independent experiments gave nine replicate values for an equivalence point that corresponds to 79.2 mole % of the total pairs of carboxyl groups. It is postulated that this represents a large molecular weight or structural fraction of the humic acid. The remaining 20.8 mole % can either bind one divalent cation to two carboxylate anions or bind one divalent cation to one carboxylate anion, with another anion providing for charge balance. Aggregation ‐ disaggregation and dissolution ‐precipitation phenomena may determine which case prevails, and they in turn are sensitive to the chemical compositions of samples. It should be possible to develop analytical chemical methods for characterizing the stoichiometric properties of humic acid samples.