Abstract Acute, lethal effects of fenthion (an organophosphate insecticide) on mysids (Mysidopsis bahia), grass shrimp (Palaemonetes pugio), pink shrimp (Penaeus duorarum) and sheepshead minnows (Cyprinodon variegatus) were determined in laboratory tests and after field applications. Exposures at four field sites ranged from short-term exposures (12 h or less) of rapidly decreasing fenthion concentrations to extended intervals (more than 72 h) with slowly increasing or decreasing fenthion concentrations. Laboratory-derived LC50s provided a reliable benchmark for predicting acute, lethal effects of fenthion on caged animals in the field when exposures persisted for 24 h or more but overestimated the toxicity for exposures of less than 24 h. Laboratory pulse-exposure tests with rapidly changing concentrations for 12 h were predictive of the nonlethal and lethal effects observed for short-term field exposures.
The design of efficient monitoring programmes required for the assurance of offshore geological storage requires an understanding of the variability and heterogeneity of marine carbonate chemistry. In the absence of sufficient observational data and for extrapolation both spatially and seasonally, models have a significant role to play. In this study a previously evaluated hydrodynamic-biogeochemical model is used to characterise carbonate chemistry, in particular pH heterogeneity in the vicinity of the sea floor. Using three contrasting regions, the seasonal and short term variability are analysed and criteria that could be considered as indicators of anomalous carbonate chemistry identified. These criteria are then tested by imposing a number of randomised DIC perturbations on the model data, representing a comprehensive range of leakage scenarios. In conclusion optimal criteria and general rules for developing monitoring strategies are identified. Detection criteria will be site specific and vary seasonally and monitoring may be more efficient at periods of low dynamics. Analysis suggests that by using high frequency, sub-hourly monitoring anomalies as small as 0.01 of a pH unit or less may be successfully discriminated from natural variability – thereby allowing detection of small leaks or at distance from a leakage source. Conversely assurance of no leakage would be profound. Detection at deeper sites is likely to be more efficient than at shallow sites where the near bed system is closely coupled to surface processes. Although this study is based on North Sea target sites for geological storage, the model and the general conclusions are relevant to the majority of offshore storage sites lying on the continental shelf.
This paper describes a numerical technique to analyze meteorological or oceanographic variables. Associated distributions of reliability are also produced. As used here, reliability is defined as 1/(2σ2), where σ is the standard error. The methods have been adapted to the analysis of 500-mb. height, sea level pressure, and sea surface temperature. Sample case studies using the first two versions are presented. As applied to 500-mb. height, for example, the technique in its current version blends information on Z and ▿Z (from winds). Information on ▿2Z (e.g., from satellite data) could also be included. All data are combined in proportion to their reliabilities. Wind components are first geostrophically converted into height differences between adjacent grid points. These estimates are then assembled with the first-guess gradients over a 5×5 set of grid points (omitting the corner ones) surrounding the wind report. Height estimates are next extrapolated to their nearest grid points using the analyzed gradient fields. These modified estimates are then assembled with the first-guess heights. The assembled height and gradient fields are then blended to form the final height and reliability fields. Provision is also made to check height and wind reports for detectable gross errors. In the sea level pressure version, ship winds are used but not those from land stations. In the analysis of sea surface temperature, the only information on gradient is that contained in the first-guess field. Otherwise, the procedures for these two versions are similar to those employed to analyze 500-mb. height.
Harnessing natural solutions to mitigate climate change requires an understanding of carbon fixation, flux, and sequestration across ocean habitats. Recent studies have suggested that exported seaweed particulate organic carbon is stored within soft-sediment systems. However, very little is known about how seaweed detritus disperses from coastlines, or where it may enter seabed carbon stores, where it could become the target of conservation efforts. Here, focusing on regionally dominant seaweed species, we surveyed environmental DNA (eDNA) from natural coastal sediments, and studied their connectivity to seaweed habitats using a particle tracking model parameterized to reproduce seaweed detritus dispersal behavior based on laboratory observations of seaweed fragment degradation and sinking. Experiments showed that seaweed detritus density changed over time, differently across species. This, in turn, modified distances traveled by released fragments until they reached the seabed for the first time, during model simulations. Dispersal pathways connected detritus from the shore to the open ocean but, importantly, also to coastal sediments, and this was reflected by field eDNA evidence. Dispersion pathways were also affected by hydrodynamic conditions, varying in space and time. Both the properties and timing of released detritus, individual to each macroalgal population, and short-term near-seabed and medium-term water-column transport pathways, are thus seemingly important in determining the connectivity between seaweed habitats and potential sedimentary sinks. Studies such as this one, supported by further field verification of sedimentary carbon sequestration rates and source partitioning, are still needed to help quantify the role of seaweed in the ocean carbon cycle. Such studies will provide vital evidence to inform on the potential need to develop blue carbon conservation mechanisms, beyond wetlands.
A Routine is described which is a collection of computer-programed techniques designed for the interpretation of meteorological satellite videograph observations. From the inferred evolution of the mass-structure distribution, the Routine diagnoses the horizontal velocity distribution for one or more isentropic surfaces. Using the horizontal velocity distribution as input, the Routine further derives net horizontal and net, vertical, parcel-displacements (in the synoptic range of scale) for specified regions and periods of time. This permits pattern configurations of layer-cloudiness to be remapped to later positions which arc consistent with the mass-motion evolutions. The use of the Routine for interpreting satellite cloud observations is illustrated by the presentation of two case studies. The layer-cloudiness distributions for the initial and terminal times of each case are analyzed primarily from the TIROS operational nephanalysis. The initial distribution of layer-cloudiness is remapped in accordance with the net horizontal displacement field. The cloud evolutions are shown and comparisons are made between the joint 24-hr. cloud displacement and net vertical, parcel-displacement patterns and the verifying 1ayer-cloudiness distributions. A close correspondence is found between the terminal position of the displaced cloudiness and the verifying cloudiness distributions. The patterns evolved in the horizontally displaced cloudiness are realistic reflections of the stages of development associated with vortex cloud patterns. Net vertical, parcel-displacement fields are generated which are consistent with conventional synoptic desiderata and the observed cloudiness. The, results indicate that the major portion of layer-cloudiness distributions in the synoptic range of scale in extratropical latitudes can be accounted for by the time-integrated, horizontal and vertical parcel-displacements. The implications of these results to the objective use of satellite data are discussed.
Abstract Coastal wetland habitats may receive pesticide inputs indirectly from agricultural and forest control of weeds and insects in upland drainage areas; indirectly or directly from weed, insect, and biofouling control from development of adjacent lands for agricultural, recreational, or residential uses; and directly from control activities practiced within wetlands for protection of public health or for nuisance abatement. Persistent and bioaccumulative pesticides used at upland sites have threatened coastal wetland biota. For more biodegradable contemporary pesticides, concerns for ecological impact are more a function of the proximity of the site of application relative to the wetland, and time available for degradation and sorption. In addition, the rate and extent of localized mixing, flushing, and stratification within the wetland can greatly affect exposure concentrations and durations for wetland biota. The short-term, direct toxic effects of pesticides on aquatic biota inhabiting coastal wetlands have been characterized in laboratory and field studies; however, assessment of the cumulative and indirect effects of repeated exposures to multiple chemicals at sublethal concentrations is a major research need.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='translate(288.889 -214.211)'/%3e%3cuse xlink:href='%23a' transform='translate(108 342.749)'/%3e%3cuse xlink:href='%23a' transform='translate(469.189 342.749)'/%3e%3c/svg%3e)
