The hydrochemistry of groundwater in the Densu River Basin, Ghana

Hydrochemical analyses of groundwater samples were used to establish the hydrochemistry of groundwater in the Densu River Basin. The groundwater was weakly acidic, moderately mineralized, fresh to brackish with conductivity ranging from of 96.6 μS cm^???1 in the North to 10,070 μS cm^???1 in the South. Densu River basin have special economic significance, representing the countries greatest hydrostructure with freshwater. Chemical constituents are generally low in the North and high in the South. The order of relative abundance of major cations in the groundwater is Na^?+??> Ca^2?+??> Mg^2?+??> K^?+? while that of anions is Cl^????> HCO $_{3}^{-} >$ SO $_{4}^{2-} >$ NO $_{3}^{-}$ . Four main chemical water types were delineated in the Basin. These include Ca–Mg–HCO₃, Mg–Ca–Cl, Na–Cl, and mixed waters in which neither a particular cation nor anion dominates. Silicate weathering and ion exchange are probably the main processes through which major ions enter the groundwater system. Anthropogenic activities were found to have greatly impacted negatively on the quality of the groundwater.     

Application of a combined measurement and modeling method to quantify windblown dust emissions from the exposed playa at Mono Lake, California

Particulate matter < or =10 microm (PM10) emissions due to wind erosion can vary dramatically with changing surface conditions. Crust formation, mechanical disturbance, soil texture, moisture, and chemical content of the soil can affect the amount of dust emitted during a wind event. A refined method of quantifying windblown dust emissions was applied at Mono Lake, CA, to account for changing surface conditions. This method used a combination of real-time sand flux monitoring, ambient PM10 monitoring, and dispersion modeling to estimate dust emissions and their downwind impact. The method identified periods with high emissions and periods when the surface was stable (no sand flux), even though winds may have been high. A network of 25 Cox sand catchers (CSCs) was used to measure the mass of saltating particles to estimate sand flux rates across a 2-km2 area. Two electronic sensors (Sensits) were used to time-resolve the CSC sand mass to estimate hourly sand flux rates, and a perimeter tapered element oscillating microbalance (TEOM) monitor measured hourly PM10 concentrations. Hourly sand flux rates were related by dispersion modeling to hourly PM10 concentrations to back-calculate the ratio of vertical PM10 flux to horizontal sand flux (K-factors). Geometric mean K-factor values (K(f)) were found to change seasonally, ranging from 1.3 x 10(-5) to 5.1 x 10(-5) for sand flux measured at 15 cm above the surface (q15). Hourly PM10 emissions, F, were calculated by applying seasonal K-factors to sand flux measurements (F = K(f) x q15). The maximum hourly PM10 emission rate from the study area was 76 g/m2 x hr (10-m wind speed = 23.5 m/sec). Maximum daily PM10 emissions were estimated at 450 g/m2 x day, and annual emissions at 1095 g/m2 x yr. Hourly PM10 emissions were used by the U.S. Environmental Protection Agency (EPA) guideline AERMOD dispersion model to estimate downwind ambient impacts. Model predictions compared well with monitor concentrations, with hourly PM10 ranging from 16 to over 60,000 microg/m3 (slope = 0.89, R2 = 0.77).     

Effective elution of RDX and TNT from particles of Comp B in surface soil

During live fire training exercises, large amounts of explosives are consumed. Low order detonations of high explosive payloads result in the patchy dispersal of particles of high explosive formulations over large areas of firing range soils. Dissolution of explosives from explosive formulation particles into soil pore water is a controlling factor for transport, fate, and effects of explosive compounds. We developed an empirical method to evaluate soils based on functionally defined effective dissolution rates. An automated Accelerated Solvent Extractor was used to determine the effective elution rates under controlled conditions of RDX and TNT from soil columns containing particles of Comp B. Contrived soils containing selected soil geosorbants and reactive surfaces were used to quantitatively determine the importance of these materials. Natural soils from training ranges of various soil types were also evaluated. The effects of geosorbants on effective elution rates were compound- and sorbent-specific. TNT elution was less than that of RDX and was greatly slowed by humic acid. Iron and iron-bearing clays reduced the effective elution rates of both RDX and TNT. This empirical method is a useful tool for directly generating data on the potential for explosives to leach from firing range soils, to identify general bulk soil characteristics that can be used to predict the potential, and to identify means to engineer soil treatments to mitigate potential transport.     

Incorporating Indigenous Rights and Environmental Justice into Fishery Management: Comparing Policy Challenges and Potentials from Alaska and Hawaiʻi

Colonial processes including the dispossession of indigenous lands and resources and the development of Western management institutions to govern the use of culturally important fish resources have served in many ways to marginalize indigenous interests within the United States fisheries. In recent years, several US fishery institutions have begun to develop policies that can confront this colonial legacy by better accommodating indigenous perspectives and rights in fishery management practices. This paper analyzes two such policies: the 2005 community quota entity program in Alaska which permits rural communities (predominantly Alaska Native villages) to purchase and lease commercial halibut fishing privileges and the 1994 State of Hawai?i community-based subsistence fishing area (CBSFA) legislation through which Native Hawaiian communities can designate marine space near their community as CBSFAs and collaborate with the state of Hawai?i to manage those areas according to traditional Hawaiian practices. The analysis reveals a striking similarity between the trajectories of these two policies. While they both offered significant potential for incorporating indigenous rights and environmental justice into state or federal fishery management, they have so far largely failed to do so. Environmental managers can gain insights from the challenges and potentials of these two policies. In order to introduce meaningful change, environmental policies that incorporate indigenous rights and environmental justice require a commitment of financial and institutional support from natural resource agencies, a commitment from indigenous groups and communities to organize and develop capacity, and careful consideration of contextual and cultural factors in the design of the policy framework.     

Substratum preferences in planula larvae of two species of scleractinian corals, Goniastrea retiformis and Stylaraea punctata

To test whether coral planulae recruit randomly to different coral reef habitats or have specific substratum preferences, the settling behavior of planulae from two shallow water coral species from Pago Bay, Guam (13°25.02N, 144°47.30E) were examined in the laboratory in June and July of 1995. Goniastrea retiformis is generally restricted to the shallow reef front (<10 m depth) in areas dominated by crustose coralline algae (CCA), while Stylaraea punctata is abundant on inner reef flats were CCA coverage is low and sand and carbonate rubble covered by biofilms is common. When presented with four substrata (1) carbonate rock scrubbed free of biofilm and dried as a control, (2) the CCA Hydrolithon reinboldii, (3) the CCA Peyssonelia sp., and (4) naturally conditioned carbonate rubble covered by a biofilm, G. retiformis larvae showed a significant preference for H. reinboldii, and S. punctata larvae for the carbonate biofilm treatment. The preference shown by S. punctata larvae for biofilmed surfaces did not diminish with increasing larval age up to 11 days. These results suggest that the larvae of both species are capable of habitat selection, and that the preferred substrata among those tested bears a relationship to the habitats in which adult colonies were found. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Lead reduces shell mass in juvenile garden snails (Helix aspersa)

In an earlier paper examining inherited tolerance to Pb, the shell growth of laboratory-bred offspring of Helix aspersa from contaminated sites was compared with that ofjuveniles from naive populations on dosed and undosed diets. Eight-week-old snails were fed either 500 microg g(-1) Pb or a control food in competitive trials between two populations. In the first series of trials, a parental history of exposure to Pb did not confer any advantage to either of two populations (BI and MI) competing with a na?ve population (LE). whether Pb was present in the diet or not. However, in the analysis of their metal concentrations reported here, LE are found to retain higher levels of Pb in the soft tissues than either BI or MI. Compared to their siblings on the unleaded diet, dosed LE and BI juveniles had lower soft tissue concentrations of Ca and Mg. Although the growth in shell height is unaffected by diet, LE and BI juveniles build lighter shells on the Pb-dosed diet, achieving around 75% of the shell mass of their controls. In contrast, the shell weights of dosed MI juveniles are depressed by only 15% and show no change in the essential metal concentrations of their soft tissues. A second experiment using five populations fed only the dosed food show that the shell weight/soft tissue weight ratios are comparable to the dosed snails of the previous experiment. Building a lighter shell thus appears to be the common response of all Helix populations to a high Pb diet, at least amongst juveniles. The reduction in its mass means that less Ca and Mg is added to the shell and, along with the lowered soft tissue concentrations observed in some populations. may be a consequence of an increased effort to excrete Pb. The possibility that the MI population shows a genotypic adaptation. perhaps as some form of modification of its Ca metabolism, is briefly discussed.     

Normal second-trimester amniotic fluid alphafetoprotein and acetylcholinesterase associated with fetal sacrococcygeal teratoma

Amniocentesis was performed at 19 weeks' gestation on a patient with two sequential serum alphafetoprotein values above 2 times median. Ultrasound examination suggested a possible sacrococcygeal teratoma. However, both amniotic fluid alphafetoprotein and acetylchol-inesterase were normal, and the patient elected to continue her pregnancy. At 24 weeks fetal demise was confirmed, and prostaglandin induction of labour produced a macerated female fetus with a large sacrococcygeal teratoma.     

AERCOARE: An overwater meteorological preprocessor for AERMOD

AERCOARE is a meteorological data preprocessor for the American Meteorological Society and U.S Environmental Protection Agency (EPA) Regulatory Model (AERMOD). AERCOARE includes algorithms developed during the Coupled-Ocean Atmosphere Response Experiment (COARE) to predict surface energy fluxes and stability from routine overwater measurements. The COARE algorithm is described and the implementation in AERCOARE is presented. Model performance for the combined AERCOARE-AERMOD modeling approach was evaluated against tracer measurements from four overwater field studies. Relatively better model performance was found when lateral turbulence measurements were available and when several key input variables to AERMOD were constrained. Namely, requiring the mixed layer height to be greater than 25 m and not allowing the Monin Obukhov length to be less than 5 m improved model performance in low wind speed stable conditions. Several options for low wind speed dispersion in AERMOD also affected the model performance results. Model performance for the combined AERCOARE-AERMOD modeling approach was found to be comparable to the current EPA regulatory Offshore Coastal Model (OCD) for the same tracer studies. AERCOARE-AERMOD predictions were also compared to simulations using the California Puff-Advection Model (CALPUFF) that also includes the COARE algorithm. Many model performance measures were found to be similar, but CALPUFF had significantly less scatter and better performance for one of the four field studies. For many offshore regulatory applications, the combined AERCOARE-AERMOD modeling approach was found to be a viable alternative to OCD the currently recommended model.

Implications: A new meteorological preprocessor called AERCOARE was developed for offshore source dispersion modeling using the U.S. Environmental Protection Agency (EPA) regulatory model AERMOD. The combined AERCOARE-AERMOD modeling approach allows stakeholders to use the same dispersion model for both offshore and onshore applications. This approach could replace current regulatory practices involving two completely different modeling systems. As improvements and features are added to the dispersion model component, AERMOD, such techniques can now also be applied to offshore air quality permitting.     

The hydrochemistry of groundwater in rural communities within the Tema District, Ghana

A detailed study has been carried out on groundwater in rural communities in the Tema District of the Greater Accra region of Ghana to establish the hydrochemistry and identify the various sources of contaminants as well assess the physical and chemical quality of the groundwater to ascertain their wholesomeness and the health impacts of the groundwater on the communities. The groundwater was found to vary considerably in terms of chemical and physical properties. Generally, the water was mildly acidic (pH 4.3–7.4), brackish to fresh, and undersaturated with respect to gypsum and halite. The majority of groundwater clustered toward Ca–Mg–SO₄ and Na–Cl facies. About 70% of boreholes sampled have elevated levels of NO₃ ^??–N, Cl^???, and SO₄ ^2? emanating from anthropogenic activities.     

GROUNDWATER RECHARGE1

The increasing need for water has increased interest in artificial recharge by water-management agencies. An evaluation of current knowledge of processes and problems of artificial recharge indicates that a great deal of additional research is necessary before recharge feasibility can be evaluated in most situations. Experience in using recharge wells on the Southern High Plains of New Mexico and Texas indicates success when using good quality water, and failure when recharge water contains high concentrations of particulate matter. Surface spreading is a more suitable method when water has a high sediment content, but may not be feasible in some hydrogeologic situations. Theoretically, well construction is important to the success of injection recharge operations, but little experimental work exists to support this view. Results of recharge experiments on the Southern High Plains support these conclusions.