MONITORING SUSPENDED PARTICULATE MATTER IN PUERTO RICO: FIELD MEASUREMENTS AND REMOTE SENSING1

ABSTRACT: The spatial distribution of suspended particulatematter (SPM) was estimated in Mayagüez Bay on the west coast of Puerto Rico by using traditional ship board measurements and remotely sensed data acquired over four days during January 1990. This effort was part of a joint project between NASA and the University of Puerto Rico to develop techniques to monitor the water quality of a Caribbean coastal zone. This paper presents the methods and algorithms developed to map and analyze short term changes in the source and spatial distribution of SPM in Mayagüez Bay by using remotely sensed data acquired by the Calibrated Airborne Multispectral Scanner (CAMS). A PC-based data acquisition system was developed to record continuous ship measurements of select in- water variables. Spectral reflectances derived from CAMS red and near-IR data were corrected for atmospheric effects and then used to generate maps of SPM. These maps displayed SPM plumes associated with the mouths of the bay's three river systems. Significant day-to-day differences in the spatial characteristics were observed, suggesting that changes in river discharge occurred. However, an analysis of estimated river discharge, sediment yield, local wind field, and thermal river plume indicates that observed sediment plumes result primarily from wind-driven resuspension events.     

Respiratory regulation and the role of the blood in the burrowing shrimp Callianassa californiensis (Decapoda: Thalassinidae)

Questions relating to oxygen extraction and hemolymph oxygen transport have been investigated in the burrowing shrimp Callianassa californiensis Dana. The relationship of oxygen consumption to oxygen tension was determined in intermolt and postmolt shrimp. Soft postmolt individuals had higher rates of oxygen consumption and a somewhat lower critical oxygen tension than intermolt specimens. Both oxygen-carrying capacity and hemocyanin content are somewhat lower in postmolt compared to intermolt shrimp. The measured gradient between postbranchial (pericardial sinus) and prebranchial (abdominal sinus) hemolymph oxygen content is small and highly variable, and is not affected by exposure to anoxic stress. Hemolymph pH and buffering capacity are high. The oxygen consumption-oxygen tension relationships and respiratory properties of the hemolymph are discussed in relation to the hypoxic environment associated with the habitat of these crustaceans.Supported in part by Institutional Sea Grant 04-3-158-4 and Public Health Service Grant HL 12326.Communicated by J.S. Pearse, Santa Cruz     

Respiratory and behavioral responses of the grass shrimp Palaemonetes pugio to cadmium and reduced dissolved oxygen

Adult grass shrimp (Palaemonetes pugio) were collected during July and August, 1973, and exposed for 48-h periods to a series of sublethal cadmium (Cd) concentrations: 0.1 and 0.56 mg l^-1 for metabolic studies; and 0.01, 0.05, 0.1, 0.3, 0.56 mg l^-1 for locomotor studies. Treatment effects were tested singly and in combination at selected dissolved oxygen (DO) concentrations ranging from near saturation to 0.8 mgl^-1. Shrimp not exposed to Cd exhibited metabolic regulation between 6.5 and, 4.6 mg DOl^-1, with progressively lower O₂ consumption rates at lower DO concentrations. Oxygen consumption of Cd-exposed shrimp was suppressed overall relative to the non-Cd treated shrimp, and with one exception, the magnitude of metabolic suppression directly corresponded to Cd concentration. Locomotor activity of non-Cd exposed shrimp was relatively independent of DO concentration down to 2.8 mg DO l^-1 and became significantly suppressed at 1.8 mg DO l^-1 and below. Significant suppression of locomotion was evident in shrimp exposed to 0.56 mg Cd l^-1, but was not seen in treatment groups of 0.3 mg Cd l^-1 or lower. No interaction on locomotor activity of shrimp was detected between Cd exposure and oxygen concentration. The reduction of locomotor activity and metabolism at 0.56 mg Cd l^-1 exposure is similar to that occurring under reduced oxygen condition. It is hypothesized that Cd acts in some manner to suppress O₂ availability to P. pugio, a suggestion consistent with literature reports on adverse effects of Cd on fish respiratory enzymes and gill tissue.Contribution No. 351 of the U.S. Environmental Protection Agency, Environmental Research Laboratory, Narragansett, Rhode Island. Although the research described in this article was funded by the U.S. Environmental Protection Agency, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred     

Modeling the effects of ozone on soybean growth and yield

A simple mechanistic model was developed based on an existing growth model in order to address the mechanisms of the effects of ozone on growth and yield of soybean [Glycine max. (L.) Merr. 'Davis'] and interacting effects of other environmental stresses. The model simulates daily growth of soybean plants using environmental data including shortwave radiation, temperature, precipitation, irrigation and ozone concentration. Leaf growth, dry matter accumulation, water budget, nitrogen input and seed growth linked to senescence and abscission of leaves are described in the model. The effects of ozone are modeled as reduced photosynthate production and accelerated senescence. The model was applied to the open-top chamber experiments in which soybean plants were exposed to ozone under two levels of soil moisture regimes. After calibrating the model to the growth data and seed yield, goodness-of-fit of the model was tested. The model fitted well for top dry weight in the vegetative growth phase and also at maturity. The effect of ozone on seen yield was also described satisfactorily by the model. The simulation showed apparent interaction between the effect of ozone and soil moisture stress on the seed yield. The model revealed that further work is needed concerning the effect of ozone on the senescence process and the consequences of alteration of canopy microclimate by the open-top chambers.     

Effects of copper and cadmium on growth,swimming and predator avoidance in Eurytemora affinis (Copepoda)

In this study we demonstrate the sensitivity of swimming behavior and predator-escape responses of nauplii of the estuarine copepod Eurytemora affinis to sublethal doses of Cu and Cd. Behavior was generally altered at metal doses below those affecting growth rates or survival of the copepods. Swimming velocities of Cu-dosed nauplii were different from controls at all concentrations of Cu tested (10–50 g l^-1 total Cu) after 24- to 48-h exposure, whereas development rate of nauplii was significantly reduced only after 96 h at 25 g l^-1. The 96 h LC50 for Cu was approximately 30 g l^-1 Cu. Naupliar swimming velocity was also affected by Cd. Swimming speeds were reduced after 24 h at 130 g l^-1, and development was slowed after 48 h at 116 g Cd l^-1. The 96-h LC50 was >120 g l^-1. Little is known of the adaptive role of specific motile behaviors in the success of larval copepods. We investigated the relationship of swimming speed to predator — prey interactions of the nauplii using both real and simulated predators. Nauplii exposed to Cu for 24 h were observed to be generally hyperactive, a condition which could increase their encounter frequency with predators. Reduced numbers of escape responses of nauplii to a simulated predator, another indication of increased vulnerability to predation, were observed only after 48-h exposure to Cu. Nevertheless, feeding rates of non-dosed larval striped bass on dosed nauplii (24 h at 25 g Cu l^-1) were significantly higher than on control nauplii. Feeding rates of larval mysid shrimp, however, were not higher on similarly dosed nauplii; 24 h exposure of nauplii to >30 g Cu l^-1 did result in increased predation by mysids.Contribution No. 272 of the US EPA Environmental Research Laboratory, Narragansett, Rhode Island 02882, USA     

Vested Interest theory and disaster preparedness

Three studies were designed to extend a combination of vested interest theory (VI) and the extended parallel process model of fear appeals (EPPM) to provide formative research for creating more effective disaster preparedness social action campaigns. The aim was to develop an effective VI scale for assessing individual awareness and ‘vestedness’ relevant to disaster preparedness. Typical preparedness behaviours are discussed with emphasis on earthquakes and tornados in particular. Brief overviews of VI and the EPPM are offered, and findings are presented from three studies (one dealing with earthquakes, and two with tornados) conducted to determine the factor structure of the key VI components involved, and to develop and test subscales derived from the two theories. The paper finishes with a discussion of future research needs and suggestions on how the new subscales may be applied in the design and execution of more effective disaster preparedness campaigns.     

Trialling a web-based spatial information management tool with Land Managers in Victoria,Australia

A prototype web-based spatial information management tool (called eFarmer) was tested for its useability and usefulness by 46 Land Managers and 5 extension staff in Victoria, Australia. Participants had a range of enterprises (dairy, beef/sheep grazing, cropping, lifestyle land use), property sizes and computer ownership and expertise. A follow up study was conducted with 12 dairy farmers, where features regarding assessment of nutrient losses from paddocks (Farm Nutrient Loss Index, FNLI) were added to eFarmer. Over 27,000 maps (including 11,000 with aerial photography) were accessed by Land Managers during a 5-month trial period. Despite limited training and support, 1350 people are registered users, and approximately 700 have actively used the tool. Reasons for the success include providing improved access to spatial information, enabling measurement of farm features and creation of farm maps, providing a basis for decision-making about farm inputs, support for better farm and landscape scale action planning and production and Land Managers being able to seek management advice from the extension staff who facilitated eFarmer testing programs. For dairy farmers in the FNLI trial, awareness of off-site impacts increased and most changed management practices. Provision of on-going training and support will be at least as important as further development of the tool itself. Web-based spatial information tools have potential to improve the awareness of Land Managers about their environmental impacts and influence their decision-making. Access to spatial information has potential to reduce information asymmetry between Land Managers, extension staff and catchment planners in a constructive way. It will also change the role of extension staff away from being an expert with answers, to a facilitator enabling learning. Results have applicability in countries where there is a high level of farm computer ownership, relevant spatial information is available in GIS format, where governments are happy to make spatial information available to the public and there is pressure for increased environmental awareness and improved decision making by Land Managers.     

Sorption and bioreduction of hexavalent uranium at a military facility by the Chesapeake Bay

Directly adjacent to the Chesapeake Bay lies the Aberdeen Proving Ground, a U.S. Army facility where testing of armor-piercing ammunitions has resulted in the deposition of >70,000 kg of depleted uranium (DU) to local soils and sediments. Results of previous environmental monitoring suggested limited mobilization in the impact area and no transport of DU into the nation's largest estuary. To determine if physical and biological reactions constitute mechanisms involved in limiting contaminant transport, the sorption and biotransformation behavior of the radionuclide was studied using geochemical modeling and laboratory microcosms (500 ppb U(VI) initially). An immediate decline in dissolved U(VI) concentrations was observed under both sterile and non-sterile conditions due to rapid association of U(VI) with natural organic matter in the sediment. Reduction of U(VI) to U(IV) occurred only in non-sterile microcosms. In the non-sterile samples, intrinsic bioreduction of uranium involved bacteria of the order Clostridiales and was only moderately enhanced by the addition of acetate (41% vs. 56% in 121 days). Overall, this study demonstrates that the migration of depleted uranium from the APG site into the Chesapeake Bay may be limited by a combination of processes that include rapid sorption of U(VI) species to natural organic matter, followed by slow, intrinsic bioreduction to U(IV).