Special Issue "Proceedings from the Fifth International Symposium on Recent Advances in Environmental Health Research"

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Abstract: This paper examines the microstructures and nanostructures for natural (mined) chrysotile asbestos nanotubes (Mg₃ Si₂O₅ (OH)₄) in comparison with commercial multiwall carbon nanotubes (MWCNTs), utilizing scanning and transmission electron microscopy (SEM and TEM). Black carbon (BC) and a variety of specific soot particulate (aggregate) microstructures and nanostructures are also examined comparatively by SEM and TEM. A range of MWCNTs collected in the environment (both indoor and outdoor) are also examined and shown to be similar to some commercial MWCNTs but to exhibit a diversity of microstructures and nanostructures, including aggregation with other multiconcentric fullerenic nanoparticles. MWCNTs formed in the environment nucleate from special hemispherical graphene “caps” and there is evidence for preferential or energetically favorable chiralities, tube growth, and closing. The multiconcentric graphene tubes (~5 to 50 nm diameter) differentiate themselves from multiconcentric fullerenic nanoparticles and especially turbostratic BC and carbonaceous soot nanospherules (~8 to 80 nm diameter) because the latter are composed of curved graphene fragments intermixed or intercalated with polycyclic aromatic hydrocarbon (PAH) isomers of varying molecular weights and mass concentrations; depending upon combustion conditions and sources. The functionalizing of these nanostructures and photoxidation and related photothermal phenomena, as these may influence the cytotoxicities of these nanoparticulate aggregates, will also be discussed in the context of nanostructures and nanostructure phenomena, and implications for respiratory health.

Abstract: Breast cancer is the leading cause of death among women between 40 and 55 years of age and is the second overall cause of death among women. Fortunately, the mortality rate from breast cancer has decreased in recent years due to an increased emphasis on early detection and more effective treatments. Despite early detection, conventional and chemotherapeutic methods of treatment, about 7% of women still died every year. Hence, the aim of the present study was to assess the therapeutic efficacy of Vernonia amygdalina (VA) leaf extracts as anti-cancer agent against human breast cancer in vitro using the MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] and alkaline single cell gel electrophoresis (Comet) assays, respectively. In this experiment, human breast adenocarcinoma (MCF-7) cells were treated with different doses of VA leaf extracts for 48 hours. Data obtained from the MTT assay showed that VA significantly ((P < 0.05) reduced the viability of MCF-7 cells in a dose-dependent manner upon 48 hours of exposure. Data generated from the comet assay also indicated a slight dose-dependent increase in DNA damage in MCF-7 cells associated with VA treatment. We observed a slight increase in comet tail-length, tail arm and tail moment, as well as in percentages of DNA cleavage at all doses tested, showing an evidence that VA-induced minimal genotoxic damage in MCF-7 cells. Taken together, our findings suggest that VA treatment moderately (P < 0.05) reduces cellular viability and induces minimal DNA damage in MCF-7 cells. These findings provide evidence that VA extracts represent a DNA-damaging anti-cancer agent against breast cancer and its mechanisms of action functions, at least in part, through minimal DNA damage and moderate toxicity in tumors cells.

Abstract: Evidence suggests that most chemotherapeutic agents are less effective as treatment in patients with estrogen receptor-negative (ER-) breast carcinomas compared to those with estrogen receptor-positive (ER+) breast carcinomas. Moreover, African American Women (AAW) is disproportionately diagnosed with ER- breast cancer compared to their white counterparts. Novel therapies effective against ER- breast carcinomas are urgently needed to ameliorate the health disparity. Previous reports show that low concentrations (microgram/ml) of water-soluble leaf extracts of a Nigerian edible plant, V. amygdalina (VA), potently retards the proliferative activities of ER+ human breast cancerous cells (MCF-7) in vitro in a concentration-dependent fashion. However, the anti-proliferative activities of VA in either ductal or ER- carcinoma cells have not been characterized. The exposure of BT-549 to increasing concentrations of VA (10, 100, and 1000 µg/mL) inhibited cell growth by approximately 14% (P<0.05), 22% (p<0.05), and 50% (p<0.005) respectively. The cell count studies were corroborated by DNA synthesis studies. Treatments of BT-549 with 10, 100, and 1000 µg/mL VA inhibited DNA synthesis in a concentration dependent fashion by 22%, 76% (P<0.05), and 86% (p<0.01) respectively. BT-549 cells were insensitive to 10 and 100 nM paclitaxel (TAX) treatments. Isolation of DNA from dried VA leaves yielded approximately 12.2 and 1 kbp genomic DNA that were Eco RI-insensitive but Hind III and Bam HI-sensitive. These pieces of information may be used to enhance the safety of medicinal botanical VA through authentication, and adulteration detection.

Abstract: The economy of the state of Tabasco is based on oil extraction. However, this imposes major effects to the environment and communities. Examples are the Polycyclic Aromatic Hydrocarbons (PAHs) that may be found in the soil, water and sediment of the region. Their volatility makes them available to living beings and results in genotoxic activity. The purpose of this study was to quantify the levels of PAHs in the air at several points in the state, and to analyze their relationship with possible damage to DNA on local inhabitants. Single Cell Gel Electrophoresis Assay (Comet Assay) was applied to peripheral blood lymphocytes of five groups of children between six and 15 years of age. PAH samples were analyzed following US/EPA TO-13-A method. Results indicated the presence in the air of most of the 16 PAHs considered as high priority by EPA, some of which have been reported with carcinogenic activity. Differences (p<0.05) were found between PAHs concentration in the gaseous component and in the particulate component of air samples, with the greatest values for the gaseous component. Greatest PAH concentrations were detected in areas with high oil extraction activities. Children groups from high oil activity areas presented genotoxic damage labeled from moderate to high according to DNA migration from nuclei (Tail Length: 14.2 - 42.14 μm and Tail/Head: 0.97 - 2.83 μm) compared with control group (12.25 and 0.63 μm, respectively). The group with greatest cell damage was located in the area with the greatest oil activity. We conclude that the presence of PAHs in the air may represent a health risk to populations that are chronically exposed to them at high oil activity regions.

Abstract: An assessment of potential health impacts of dioxin and dioxin-like compounds in recycled water for indirect potable reuse was conducted. Toxic equivalency factors (TEFs) for 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs) congeners have been developed by the World Health Organization to simplify the risk assessment of complex mixtures. Samples of secondary treated wastewater in Perth, Australia were examined pre-and post-tertiary treatment in one full-scale and one pilot water reclamation plant. Risk quotients (RQs) were estimated by expressing the middle-bound toxic equivalent (TEQ) and the upper-bound TEQ concentration in each sampling point as a function of the estimated health target value. The results indicate that reverse osmosis (RO) is able to reduce the concentration of PCDD, PCDF and dioxin-like PCBs and produce water of high quality (RQ after RO=0.15). No increased human health risk from dioxin and dioxin-like compounds is anticipated if highly treated recycled water is used to augment drinking water supplies in Perth. Recommendations for a verification monitoring program are offered.

Abstract: We observed a slight drop in the growth of Xenopus laevis and Pseudacris triseriata larvae following acute exposure (24-48 h) during egg development to three concentrations of TCDD (0.3, 3.0, 30.0 μg/l). Our exposure protocol was modeled on a previous investigation that was designed to mimic the effects of maternal deposition of TCDD. The doses selected were consistent with known rates of maternal transfer between mother and egg using actual adult body burdens from contaminated habitats. Egg and embryonic mortality immediately following exposure increased only among 48 h X. laevis treatments. Control P. triseriata and X. laevis completed metamorphosis more quickly than TCDDtreated animals. The snout-vent length of recently transformed P. triseriata did not differ between treatments although controls were heavier than high-dosed animals. Likewise, the snout-vent length and weight of transformed X. laevis did not differ between control and TCDD treatments. These findings provide additional evidence that amphibians, including P. triseriata and X. laevis are relatively insensitive to acute exposure to TCDD during egg and embryonic development. Although the concentrations selected for this study were relatively high, they were not inconsistent with our current understanding of bioaccumulation via maternal transfer.

Abstract: Nearly three decades after its discovery, HIV infection remains the number one killer disease in Sub-Saharan Africa where up to 67% of the world’s 33 million infected people live. In Cameroon, based on a Demographic Health Survey carried out in 2004, the national HIV prevalence is estimated at 5.5% with women and youths being predominantly infected. Orphans and vulnerable children (OVC) from the HIV and AIDS pandemic have increased steadily over the years; hospital occupancy is estimated at about 30%, hence stretching the health system; co-infections like HIV/tuberculosis have been reported to reach 40-50% of infected cases and 95% of teachers are said not to be productive on several counts. Thus, the impact is multi-sectorial. Furthermore, the HIV epidemic in Cameroon is peculiar because of the wide HIV-1 genetic diversity of HIV-1 Group M observed with several subtypes reported (A, B, C, D, F, G, H, J, K), predominantly subtype A. There are also circulating recombinant forms, mainly CRF02_AG. In addition, HIV-1 Groups O and N have all been noted in Cameroon. These findings have great implications not only for HIV diagnosis, but also for responsiveness to therapy as well as for vaccine development. In 1986, the initial response of the Cameroon government to the increasing trends in the HIV/AIDS infection was to create a National AIDS Control Committee to coordinate a national AIDS programme. By 2000, the first National Strategic Plan was drawn for 2000-2005. The second National Strategic Plan for 2006-2010 is currently being implemented and covers various axes. Some results obtained show that there has been significantly positive outcomes noted in the various arms of intervention by the Cameroon government.

Abstract: The South East Asian Tsunami in Thailand and Hurricane Katrina in the United States were natural disasters of different origin but of similar destruction and response. Both disasters exhibited synonymous health outcomes and similar structural damage from large surges of water, waves, and flooding. A systematic discussion and comparison of the disasters in Thailand and the Gulf Coast considers both calamities to be similar types of disaster in different coastal locations. Thus valuable comparisons can be made for improvements in response, preparedness and mitigation. Research needs are discussed and recommendations made regarding potential methologies. Recommendations are made to: (1) improve disaster response time in terms of needs assessments for public health and environmental data collection; (2) develop an access-oriented data sharing policy; and (3) prioritize natural geomorphic structures such as barrier islands, mangroves, and wetlands to help reduce the scale of future natural disasters. Based on the experiences gained opportunities to enhance disaster preparedness through research are presented.

Abstract: Epidemiological studies commonly test multiple null hypotheses. In some situations it may be appropriate to account for multiplicity using statistical methodology rather than simply interpreting results with greater caution as the number of comparisons increases. Given the one-to-one relationship that exists between confidence intervals and hypothesis tests, we derive a method based upon the Hochberg step-up procedure to obtain multiplicity corrected confidence intervals (CI) for odds ratios (OR) and by analogy for other relative effect estimates. In contrast to previously published methods that explicitly assume knowledge of P values, this method only requires that relative effect estimates and corresponding CI be known for each comparison to obtain multiplicity corrected CI.

Abstract: Based on a citizen’s report, a house-to-house survey was conducted in Talwandi Sabo and Chamkaur Sahib Community Development Blocks in Bathinda and Roop Nagar District respectively in Punjab state located in a northern part of India to identify the number of existing cancer cases, and the number of cancer deaths that occurred in the last 10 years. Age adjusted prevalence of confirmed cancer cases per 100,000 population was 125 (107/85315) in Talwandi Sabo and 72 (71/97928) in Chamkaur Sahib. Cancer of female reproductive system, i.e., breast, uterus/cervix and ovary were more common in Talwandi sabo whereas cancer of blood and lymphatic system, esophagus, and bones were more common in Chamkaur Sahib. Cancer deaths per 100,000 populations per year were 52 in Talwandi Sabo compared to 30 at Chamkaur Sahib. A comparison of the characteristics of randomly selected individuals, from the villages where a cancer case existed or death due to cancer had occurred in last 2 years, revealed that involvement in cultivation, pesticide use, alcohol consumption and smoking were more common in Talwandi Sabo as compared to Chamkaur Sahib. Limited studies show that in drinking water the levels of heavy metals such as As, Cd, Cr, Se, Hg were generally higher, and pesticides such as heptachlor, ethion, and chloropyrifos were also higher in samples of drinking water, vegetables, and blood in Talwandi Sabo as compared to Chamkaur Sahib. As multiple factors were responsible for significantly higher prevalence of cancer cases in Talwandi Sabo, therefore, a multi-pronged strategy to discourage the indiscriminate use of pesticides, tobacco and alcohol needs to be adopted for cancer prevention, and a cancer registry should be set up for elucidation of the role of pesticides and heavy metals in the etiology of cancer in this area.

Abstract: Commercially available St. John’s wort supplement (SJWS) composed of an herbal mixture of St. John’s Wort (SJW), Rosemary (RM) and Spirulina (SP) is used as a dietary supplement for the treatment of psychiatric disorders. Although the minor ingredients, (RM and SP) are proven antioxidants, their quantity is quite insignificant as compared to the SJW, which is the major ingredient. Most of the toxic effects of SJWS are attributed to the main constituents of SJW which differ due to the influence of light (hypericin) and variations in temperature above freezing point (hyperforin). However, there are no reports on toxicity of SJWS maintained at room temperature in pharmacies and supermarkets. In view of the folkloric importance, immense (prescribed or unprescribed) use and a paucity of literature on SJWS, it was found worthwhile to (1) determine the genotoxic effects of SJWS in somatic and germ cells of mice and (2) investigate the role of biochemical changes, as a possible mechanism. The protocol included the oral treatment of mice with different doses (380, 760 and 1520 mg/kg/day) of SJWS for 7 days. The following experiments were conducted: (i) cytological studies on micronucleus test, (ii) cytogenetic analysis for meiotic chromosomes, (iii) cytological analysis of spermatozoa abnormalities, (iv) quantification of proteins and nucleic acids in hepatic and testicular cells and (v) estimation of malondialdehyde (MDA) and nonprotein sulfhydryl (NP-SH) in hepatic and testicular cells. The treatment increased the frequency of micronuclei in polychromatic erythrocytes (PCE) in the femora. It caused aberrations in chromosomes of testes and induced spermatozoa abnormalities. These changes might be attributed to the epigenetic mechanisms as revealed by an increase in concentrations of MDA and depletion of nucleic acids and NP-SH levels in both hepatic and testicular cells observed in the present study. Since, the samples of SJWS used were not drawn from extremities of light and temperature; the observed effect might not be related to the main constituents of SJW. However, these changes might be ascribed to the combined effect of terpenes, tannins, quercetin and flavonoids present in SJW.

Abstract: Oral health is an integral component of general health and well being and a basic human right. Dental public health is probably the most challenging specialty of dentistry. Because of the lack of adequate resources among other factors, many people are likely to suffer from dental diseases. Despite great improvements in the oral health status of populations across the world, the burden and impact of dental diseases are still high. This is particularly true among underprivileged groups in both developed and developing communities. Oral diseases and conditions, including oral cancer, oral manifestations of HIV/AIDS, dental trauma, craniofacial anomalies, and noma, all have broad impacts on health and well-being. Oral cancer, the sixth most common cancer worldwide continues to be most prevalent cancer related to the consumption of tobacco, alcohol and other carcinogenic products. Nevertheless, significant reduction in mortality can be achieved by advances in early diagnosis and implementation of multidisciplinary treatment programs leading to improvement of survivorship and better quality of life. The present study was designed to evaluate the immunologic and biochemical markers in oral carcinogenesis using circulating immune complexes (CIC), copper, iron, and selenium concentrations as assessment endpoints. Study results indicated an increase in CIC and copper levels, and a decrease in iron and selenium concentrations in oral cancer patients compared to controls. The implications of these findings for public health are discussed.

Abstract: The present study was undertaken to evaluate the influence of butachlor, a widely used herbicide, on antioxidant enzyme system and lipid peroxidation formation in African cat fish (Clarias gariepinus). Fish were exposed to sub-lethal concentrations of butachlor 1, 2, 2.5 ppm and sacrificed 24hrs after treatment. A significant increase in malondialdehyde formation was observed in the liver, kidney, gills and heart of the fish following exposure to different concentrations of butachlor. Superoxide dismutase and catalase activities increased in the liver and kidney but decreased in the gills and heart in a concentration-dependent pattern. Glutathione level and glutathione-Stransferase activities increased (P<0.05) in the liver but decreased in the kidneys, gills and heart when fishes were exposed to the three concentrations of butachlor. The results suggest that butachlor induced oxidative stress in the various tissues of the fish particularly in the kidney and as such the organ may be subjected to severe oxidative toxicity due to depressed glutathione detoxification system.

Abstract: Lead (Pb), depending upon the reactant surface, pH, redox potential and other factors can bind tightly to the soil with a retention time of many centuries. Soil-metal interactions by sorption, precipitation and complexation processes, and differences between plant species in metal uptake efficiency, transport, and susceptibility make a general prediction of soil metal bioavailability and risks of plant metal toxicity difficult. Moreover, the tight binding characteristic of Pb to soils and plant materials make a significant portion of Pb unavailable for uptake by plants. This experiment was conducted to determine whether the addition of ethylenediaminetetraacetic acid (EDTA), ethylene glycol tetraacetic acid (EGTA), or acetic acid (HAc) can enhance the phytoextraction of Pb by making the Pb soluble and more bioavailable for uptake by coffeeweed (Sesbania exaltata Raf.). Also we wanted to assess the efficacy of chelates in facilitating translocation of the metal into the above-ground biomass of this plant. To test the effect of chelates on Pb solubility, 2 g of Pb-spiked soil (1000 mg Pb/kg dry soil) were added to each 15 mL centrifuge tube. Chelates (EDTA, EGTA, HAc) in a 1:1 ratio with the metal, or distilled deionized water were then added. Samples were shaken on a platform shaker then centrifuged at the end of several time periods. Supernatants were filtered with a 0.45 μm filter and quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES) to determine soluble Pb concentrations. Results revealed that EDTA was the most effective in bringing Pb into solution, and that maximum solubility was reached 6 days after chelate amendment. Additionally, a greenhouse experiment was conducted by planting Sesbania seeds in plastic tubes containing top soil and peat (2:1, v:v) spiked with various levels (0, 1000, 2000 mg Pb/kg dry soil) of lead nitrate. At six weeks after emergence, aqueous solutions of EDTA and/or HAc (in a 1:1 ratio with the metal) or distilled deionized water were applied to the root zones. Plants were harvested at 6 days after chelate addition to coincide with the duration of maximum metal solubility previously determined in this study. Results of the greenhouse experiment showed that coffeeweed was relatively tolerant to moderate levels of Pb and chelates as shown by very slight reductions in root and no discernable effects on shoot biomass. Root Pb concentrations increased with increasing levels of soil-applied Pb. Further increases in root Pb concentrations were attributed to chelate amendments. In the absence of chelates, translocation of Pb from roots to shoots was minimal. However, translocation dramatically increased in treatments with EDTA alone or in combination with HAc. Overall, the results of this study indicated that depending on the nature and type of Pb-contaminated soil being remediated, the bioavailability and uptake of Pb by coffeeweed can be enhanced by amending the soil with chelates especially after the plants have reached maximum biomass.

Abstract: Lead (Pb) is recognized as one of the most pervasive environmental health concerns in the industrialized world. While there has been a substantial reduction in the use of Pb in gasoline, water pipes, and Pb-based residential paint, residual Pb from their use is still in the environment and constitutes an important source of Pb in the atmosphere, water, and soil. Soil acts as a sink for these anthropogenic sources of Pb, accumulating the deposits over time in the upper 2 - 5 cm of undisturbed soil. Generally, Pb binds strongly to soil particles and renders a significant soil-metal fraction insoluble and largely unavailable for phytoremediation or plant uptake. A major objective of current phytoremediation research, therefore, is to induce desorption of Pb from the soil matrix into solution and increase the propensity for plant uptake. We hypothesized that the bioavailability of Pb for plant uptake can be increased through chelate amendments. To test this hypothesis, we mixed delta top soil and peat (2:1) and added lead nitrate [Pb (NO3)2] to generate a Pb-contaminated soil concentration of 2000 mg Pb/kg dry soil. After incubating the Pb-spiked soil in a greenhouse for 6 weeks, Sesbania plants were grown in the soil and harvested at 6, 8, and 10 weeks after emergence. Six days before each harvest, a chelating agent, ethylenediaminetetraacetic acid (EDTA) was applied to the root zone as an aqueous solution in a 1:1 ratio with the Pb concentration in the soil. Sequential extraction procedures were used to assess selective chemical fractions of Pb in the soil. Our results showed that a higher exchangeable fraction of Pb was available for plant uptake after chelate amendment compared to pre-chelate amendment. We also saw higher root and shoot Pb uptake after chelate amendment compared to pre-chelate amendment, especially at 10 weeks after emergence. Together, these results suggest that chelate amendments can promote the bioavailability of Pb in the soil and increased the propensity for uptake by plants into roots and shoots. Further, these results indicate that Sesbania exaltata can be grown under elevated Pb conditions and may be suitable as a potential crop rotation species for phytoextraction.

Abstract: An area near the city of Chihuahua has been traditionally irrigated with wastewater to grow forage crops. It has been hypothesized that metal levels could be found in these soils high enough to cause potential health problems to the population. The objective of this study was to determine heavy metal concentrations in different soils due to irrigation practices. Four soil types were evaluated; a soil with a past and present history of wastewater irrigation (S1), a soil with a history of wastewater irrigation until 2003 (S2), a soil with no irrigation history (S3), and a soil similar to S1 and adjacent to the river where the wastewater is transported (S11). Three soil depths were evaluated; 0-15, 15-30 and 30-50 cm. Consequently, a total of 150 soil samples were analyzed evaluating pH, EC, OM and the following elements; Na, K, Cd, Pb, Ni, Cr, Cu and Fe. The pH (P=0.000) and EC (P=0.000) were different for each soil type but no differences were noted for soil depth and the interaction. Maximum pH levels were noted in S3 with a value of 8.74 while maximum EC was observed in S1 with a value of 0.850 dSm^-1. The OM level was different for soil type (P=0.000), soil depth (P=0.005) and the interaction (P=0.014). S1 and S11 obtained maximum levels of OM while minimum levels were noted in S3. Maximum OM levels were observed at the 0-15 cm depth followed by the 15-30 cm depth and finally at the 30-50 cm depth. The highest concentration of metals was as follows: K in S1 (359.3 mg kg^-1); Cd in S1 (4.48 mg kg^-1); Pb in S11 (155.83 mg kg^-1); Ni in S1 (10.74 mg kg^-1); Cu in S1 (51.36 mg kg^-1); B in S3 (41.5 mg kg^-1); Fe in S3 (20,313.0 mg kg^-1), Cr in S3 (44.26 mg kg^-1) and Na in S3 (203.0 mg kg^-1). The conclusion is that some metals are present in the soils due to anthropogenic activities but others are present in natural forms.

Abstract: Lead (Pb) is a common environmental contaminant found in soils. Unlike other metals, Pb has no biological role, and is potentially toxic to microorganisms. Effects of low (1 ppm) and high (500-2000) levels of lead (Pb) upon the soil microbial community was investigated by the PCR/DGGE analysis of the 16S and nirK gene markers, indicative of general microbial community and denitrifying community, respectively. Community analysis by use of those markers had shown that Pb has detectable effects upon the community diversity even at the lowest concentration tested. Analysis of sample diversity and similarity between the samples suggested that there are several thresholds crossed as metal concentration increase, each causing a substantial change in microbial diversity. Preliminary data obtained in this study suggest that the denitrifying microbial community adapts to elevated levels of Pb by selecting for metal-resistant forms of nitrite reductases.

Abstract: Industrial districts became important instruments which are used by the Public Power to induce economic decentralization and create new development poles. For this reason the legislative process is an indispensable means to define the priorities in the uses of soil, also to conduct and follow the process of industrial registration. However, the industrial district establishment shall not be analyzed by taking into account just the economic factor, but also the environmental issue of the enterprise. Thus, this research has the objective of determining adequate places for industrial districts implantation, having as a pilot area the city of São Leopoldo, Rio Grande do Sul State, Brazil. A Geographic Information System for execution of spatial analysis and criteria creation on a large volume of environmental information will be used as a tool, which will be guided by the Municipal, State and Federal legislation and a Quickbird satellite image that covers the interest area. The main information used on this research are: altimeter, hydrography, soil use, pedology, geology and infrastructure. The results are visualized in scenarios modeled in accordance with the restrictions imposed upon the information, allowing at the end, to combine all scenarios and create through the multiple criteria method a map that indicates adequate places for implantation of industrial districts.

Abstract: In this paper, we present the applications of spatial technologies—Geographic Information Systems (GIS) and remote sensing—in the international monitoring of river basins particularly analyzing the ecological, hydrological, and socio-economic issues along the Senegal River. The literature on multinational water crisis has for decades focused on mediation aspects of trans-boundary watershed management resulting in limited emphasis placed on the application of advances in geo-spatial information technologies in multinational watershed conservation in the arid areas of the West African sub-region within the Senegal River Basin for decision-making and monitoring. While the basin offers life support in a complex ecosystem that stretches across different nations in a mostly desert region characterized by water scarcity and subsistence economies, there exists recurrent environmental stress induced by both socio-economic and physical factors. Part of the problems consists of flooding, drought and limited access to sufficient quantities of water. These remain particularly sensitive issues that are crucial for the health of a rapidly growing population and the economy. The problems are further compounded due to the threats of climate change and the resultant degradation of almost the region’s entire natural resources base. While the pace at which the institutional framework for managing the waters offers opportunities for hydro electricity and irrigated agriculture through the proliferation of dams, it has raised other serious concerns in the region. Even where data exists for confronting these issues, some of them are incompatible and dispersed among different agencies. This not only widens the geo-spatial data gaps, but it hinders the ability to monitor water problems along the basin. This study will fill that gap in research through mix scale methods built on descriptive statistics, GIS and remote sensing techniques by generating spatially referenced data to supplement the existing ones for the management of the Senegal River Basin. The results show the incidence of change predicated on pressures from demography, natural forces and the proliferation of river basin development which resulted in more irrigated areas to meet the needs of the inhabitants of the basin. With the substantial increase in bare surface areas, the basin faces growing exposure to the threats of desertification.

Abstract: Remote sensing of terrestrial vegetation has been successful thanks to the unique spectral characteristics of green vegetation, low reflectance in red and high reflectance in Near-InfraRed (NIR). These spectral characteristics were used to develop vegetation indices, including Normalized Difference Vegetation Index (NDVI). However, the NIR absorption by water and light scattering from suspended particles reduces the practical application of such indices in aquatic vegetation studies, especially for the Submerged Aquatic Vegetation (SAV) that grows below water surface. We experimentally tested if NDVI can be used to depict canopies of aquatic plants in shallow waters. A 100-gallonoutdoor tank was lined with black pond liners, a black panel or SAV shoots were mounted on the bottom, and filled with water up to 0.5 m. We used a GER 1500 spectroradiometer to collect spectral data over floating waterhyacinth (Eichhornia crassipes) and also over the tanks that contain SAV and black panel at varying water depths. The measured upwelling radiance was converted to % reflectance; and we integrated the hyperspectral reflectance to match the Red and NIR bands of three satellite sensors: Landsat 7 ETM, SPOT 5 HRG, and ASTER. NDVI values ranged 0.6-0.65 when the SAV canopy was at the water level, then they decreased linearly (slope of 0.013 NDVI/meter) with water depth increases in clear water. When corrected for water attenuation using the data obtained from the black panel, the NDVI values significantly increased at all depths that we tested (0.1 – 0.5 m). Our results suggest the conventional NDVI: (1) can be used to depict SAV canopies at water surface; (2) is not a good indicator for SAV that is adapted to live underwater or other aquatic plants that are submerged during flooding even at shallow waters (0.3 m); and (3) the index values can significantly improve if information on spectral reflectance attenuation caused by water volume increases is collected simultaneously through ground-truthing and integrated.

Abstract: Coastal atmospheric conditions widely vary from those over inland due to the land-sea interface, temperature contrast and the consequent development of local circulations. In this study a field meteorological experiment was conducted to measure vertical structure of boundary layer during the period 25-29 June, 2007 at three locations Seabee base, Harrison and Wiggins sites in the Mississippi coast. A GPS Sonde along with slow ascent helium balloon and automated weather stations equipped with slow and fast response sensors were used in the experiment. GPS sonde were launched at three specific times (0700 LT, 1300 LT and 1800 LT) during the experiment days. The observations indicate shallow boundary layer near the coast which gradually develops inland. The weather research and forecasting (WRF) meso-scale atmospheric model and a Lagrangian particle dispersion model (HYSPLIT) are used to simulate the lower atmospheric flow and dispersion in a range of 100 km from the coast for 28-30 June, 2007. The simulated meteorological parameters were compared with the experimental observations. The meso-scale model results show significant temporal and spatial variations in the meteorological fields as a result of development of sea breeze flow, its coupling with the large scale flow field and the ensuing alteration in the mixing depth across the coast. Simulated ground-level concentrations of SO₂ from four elevated point sources located along the coast indicate diurnal variation and impact of the local sea-land breeze on the direction of the plume. Model concentration levels were highest during the stable morning condition and during the sea-breeze time in the afternoon. The highest concentrations were found up to 40 km inland during sea breeze time. The study illustrates the application of field meteorological observations for the validation of WRF which is coupled to HYSPLIT for dispersion assessment in the coastal region.