Fish Species Used as Biomarker for Heavy Metal and Hydrocarbon Contamination for Cross River, Nigeria

Enhanced concentrations of Fe, Zn, Mn, Pb, Cu, Cd and total hydrocarbons (THC) determined in fish samples from the Cross River system, Nigeria have been associated with clinical defects (nausea, headache, hepatitis, body rashes) observed in coastal residents who are the major consumers of the fish species. Fish samples were collected from ten locations with varying degrees of exposure to human activities. Heavy metal concentrations in fish followed the sequence: Fe>Zn>Mn>Pb>Cu>Cd with the highest concentration of 243 g/g (Fe) wet weight occurring in Tympanotonus sp. Fe levels were significantly (P<0.001) higher than other metals analysed. The sequence in total hydrocarbon concentrations according to fish species was in the order of O. niloticus (55.1 g/g) > E. fimbriata > P. elongatus > Portonus sp. > C. nigrodigitatus > Tympanotonus sp. Generally, the demersal species showed a marked potential for tolerating high levels of heavy metals while the pelagic species showed preference for the accumulation of hydrocarbons. The degree of contamination depended on pollutant type, fish species, sampling location, trophic level and their mode of feeding. The persistent accumulation and tolerable potential of Tympanotonus, Portonus and P. elongatus suggest that they might be effectively utilized as self-integrating indicators for time-series monitoring of the rate of recovery of the impacted ecosystem by heavy metals. Possible sources of pollutant include leachates from municipal dumps, used crankcase oils from fluvial discharges (mechanic workshops) and occasional oil spills.     

Preparation and FT-IR characterization of metal phytate compounds

Phytic acid (inositol hexaphosphoric acid, IP6) has long been recognized as the predominant organic P form in soil and animal manure. Whereas many studies have investigated the wet chemistry of IP6, there is little information on the characterization of solid metal IP6 compounds. This information is essential for further understanding and assessing the chemical behavior of IP6 in diverse soil-plant-water ecosystems. As the first step in full characterization, we synthesized eight metal phytate compounds and investigated their structural features using Fourier transform infrared spectroscopy (FT-IR). The absorption features from 900 to 1200 cm(-1) in FT-IR could be used to identify these phytates as: (i) light divalent metal (Ca and Mg) compounds with a sharp band and a broad band, (ii) heavy divalent metal (Cu and Mn) compounds with splitting broad bands, and (iii) trivalent metal (Al and Fe) compounds with a broad band and a shoulder band. Three different types of chemical structures of metal-phytate compounds were presented based on the FT-IR information. We further demonstrated that metal orthophosphates possessed different FT-IR spectral characteristics from their IP6 counterparts. The unique spectral features of metal phytates from 1000 to 700 cm(-1) could be used to distinguish phytate compounds from metal phosphate compounds. Thus, FT-IR analysis after fine tuning could provide an analytical tool to investigate the basic metal phytate chemistry in molecular levels, such as the competitive interactions between phosphate and phytate with a specific metal ion, and the conversion (or hydrolysis) of metal phytate to metal phosphate under various conditions.     

Design of environmentally and socially conscious water metering tariffs for the UK

England is one of the few industrialised countries where water metering is not compulsory. Most households instead pay a fixed charge regardless of use. Yet water consumption is already at the limit of resources and beyond them in some regions. Despite the need to control demand, compulsory water metering has not been implemented largely because of concerns about the regressive impact on poorer households. This research analysed new data from Anglian Water on household water consumption and income to examine the distributional impacts of ten different hypothetical tariff designs. It was found that it was possible to design revenue-neutral metered tariffs that would cause only a small percentage of low-income households to lose and most to gain. With sensitive design, the social concerns about compulsory water metering can be dealt with.     

GROUPWISE MODELING STUDY OF BACTERIALLY IMPAIRED WATERSHEDS IN TEXAS: CLUSTERING ANALYSIS1

ABSTRACT: Under the Clean Water Act (CWA) program, the Texas Commission on Environmental Quality (TCEQ) listed 110 stream segments in the year 2000 with pathogenic bacteria impairment. A study was conducted to evaluate the probable sources of pollution and characterize the watersheds associated with these impaired water bodies. The primary aim of the study was to group the water bodies into clusters having similar watershed characteristics and to examine the possibility of studying them as a group by choosing models for total maximum daily load (TMDL) development based on their characteristics. This approach will help to identify possible sources and determine appropriate models and hence reduce the number of required TMDL studies. This in turn will help in reducing the effort required to restore the health of the impaired water bodies in Texas. The main characteristics considered for the classification of water bodies were land use distribution within the watershed, density of stream network, average distance of land of a particular use to the closest stream, household population, density of on‐site sewage facilities (OSSFs), bacterial loading from different types of farm animals and wildlife, and average climatic conditions. The climatic data and observed instream fecal coliform bacteria concentrations were analyzed to evaluate seasonal variability of instream water quality. The grouping of water bodies was carried out using the multivariate statistical techniques of factor analysis/principal component analysis, cluster analysis, and discriminant analysis. The multivariate statistical analysis resulted in six clusters of water bodies. The main factors that differentiated the clusters were found to be bacterial contribution from farm animals and wildlife, density of OSSFs, density of households connected to public sewers, and land use distribution.     

Effects of an Experimental Enrichment of Instream Habitat Heterogeneity on the Stream Bed Morphology and Chironomid Community of a Straightened Section in a Sandy Lowland Stream

A straightened stream stretch with poor habitat heterogeneity was divided into a “control” section with a low amount of submerged woody debris and an experimentally “wood-enriched” downstream section to study the effect of enhanced habitat diversity on the benthic invertebrate community. The downstream section was enriched by fixing 25 wood packages constructed from 9–10 branches on the stream bottom. Succession processes occurring in the two stream sections were compared by chironomid exuviae drift from July to November 2000 and from April to August 2001. During the first sampling period, more drifting chironomid exuviae (medians of control vs. wood-enriched: 446 vs. 331, no significant difference) and total number of taxa (44 vs. 36, Wilcoxon signed-rank test P = 0.019) were recorded for the control section. Although species compositions of both stream sections were highly similar (Sørensen index: 0.83) the diversity in the wood-enriched section was distinctly lower compared to the control section (Shannon–Weaver index: 1.19 vs. 1.50). During the second sampling period, exuviae numbers remained higher in the control section (median: 326 vs. 166), but total numbers of taxa were nearly equal (51 vs. 49), as well as species diversity (Shannon–Weaver index: 1.67 vs. 1.64). The lower chironomid diversity observed during the first sampling period coincided with a gradual but significant change of the streambed morphology in the wood-enriched section. There, the initially more U-shaped profile (V/U = 0.81 ± 0.37) had turned into a pronounced V shape (V/U = 1.14 ± 0.21), whereas the control section retained its unaltered U shape (V/U = 0.62–0.75). This small-scale study on experimental of woody debris in sandy lowland streams showed that the negative impact of increased hydraulic disturbance of the existing streambed more than outweighed any positive impact resulting from the increase in woody debris.     

INTEGRATING LANDSCAPE ASSESSMENT AND HYDROLOGIC MODELING FOR LAND COVER CHANGE ANALYSIS1

ABSTRACT: Significant land cover changes have occurred in the watersheds that contribute runoff to the upper San Pedro River in Sonora, Mexico, and southeast Arizona. These changes, observed using a series of remotely sensed images taken in the 1970s, 1980s, and 1990s, have been implicated in the alteration of the basin hydrologic response. The Cannonsville subwatershed, located in the Catskill/Delaware watershed complex that delivers water to New York City, provides a contrast in land cover change. In this region, the Cannonsville watershed condition has improved over a comparable time period. A landscape assessment tool using a geographic information system (GIS) has been developed that automates the parameterization of the Soil and Water Assessment Tool (SWAT) and KINEmatic Runoff and EROSion (KINEROS) hydrologic models. The Automated Geospatial Watershed Assessment (AGWA) tool was used to prepare parameter input files for the Upper San Pedro Basin, a subwatershed within the San Pedro undergoing significant changes, and the Cannonsville watershed using historical land cover data. Runoff and sediment yield were simulated using these models. In the Cannonsville watershed, land cover change had a beneficial impact on modeled watershed response due to the transition from agriculture to forest land cover. Simulation results for the San Pedro indicate that increasing urban and agricultural areas and the simultaneous invasion of woody plants and decline of grasslands resulted in increased annual and event runoff volumes, flashier flood response, and decreased water quality due to sediment loading. These results demonstrate the usefulness of integrating remote sensing and distributed hydrologic models through the use of GIS for assessing watershed condition and the relative impacts of land cover transitions on hydrologic response.     

A GIS-based approach for assessing the regional conservation status of genetic diversity: an example from the southern Appalachians

Conserving genetic diversity requires an assessment of the distribution of genetic variants in relation to patterns of land use and environmental variation at a regional scale. This assessment requires a novel approach to integrating and analyzing the genetic and environmental data across spatial scales. To explore the integration of genetic data with other geospatial data sets, we developed a GIS-based approach for examining patterns of genetic diversity for several species of salamanders in southern Appalachians. The genetic data, from allozyme surveys in the genetics literature, were integrated into a GIS database along with related attributes including population identifications and spatial locations. Using existing geospatial data, we classified sample locations as being either protected from anthropogenic disturbance (e.g., National Parks, Wilderness Areas) or as unprotected (e.g., private lands, multiple-use lands in National Forests). We used multidimensional scaling of allelic frequencies and contributions of populations to interpopulation differences in allelic richness to determine which populations had genetic characteristics most different from other populations in the sample. Measures of genetic differentiation were integrated into the GIS database to facilitate spatial analysis and visualization of the indices in relation to land use. This approach was useful for both identification of populations with components of genetic variation that were not well represented at protected sites and for identifying areas of species distributions where more genetic sampling would be necessary to make informed management decisions. Our approach could be readily adapted for use by managers and geneticists working with other species and types of genetic markers.     

ESTIMATION OF LONG-TERM DISCHARGE STATISTICS BY REGIONAL ADJUSTMENT1

ABSTRACT: A regional adjustment relationship was developed to estimate long-term (30-year) monthly median discharges from short term (three-year) records. This method differs from traditional approaches in that it is based on site-specific discharge data but does not require correlation of these data with discharges from a single hydrologically similar long-term gage. The method is shown to be statistically robust, and applicable to statistics other than the median.     

Environmental strategies: A case study of systematic evaluation

A major problem facing environmental managers is the necessity to effectively evaluate management alternatives. Traditional environmental assessments have emphasized the use of economic analyses. These approaches are often deficient due to difficulty in assigning dollar values to environmental systems and to social amenities. A more flexible decisionmaking model has been developed to analyze management options for coping with beach erosion problems at the Sandy Hook Unit of Gateway National Recreation Area in New Jersey. This model is comprised of decision-making variables which are formulated from a combination of environmental and management criteria, and it has an accept-reject format in which the management options are analyzed in terms of the variables. Through logical ordering of the insertion of the variables into the model, stepwise elimination of alternatives is possible. A hierarchy of variables is determined through estimating work required to complete an assessment of the alternatives for each variable. The assessment requiring the least work is performed first so that the more difficult evaluation will be limited to fewer alternatives. The application of this approach is illustrated with a case study in which beach protection alternatives were evaluated for the United States National Park Service.Portions of this paper have been excerpted from Sherman and Garès (1978).     

On the Design of Computer-Based Models for Integrated Environmental Science

The current research agenda in environmental science is dominated by calls to integrate science and policy to better understand and manage links between social (human) and natural (nonhuman) processes. Freshwater resource management is one area where such calls can be heard. Designing computer-based models for integrated environmental science poses special challenges to the research community. At present it is not clear whether such tools, or their outputs, receive much practical policy or planning application. It is argued that this is a result of (1) a lack of appreciation within the research modeling community of the characteristics of different decision-making processes including policy, planning, and (2) participation, (3) a lack of appreciation of the characteristics of different decision-making contexts, (4) the technical difficulties in implementing the necessary support tool functionality, and (5) the socio-technical demands of designing tools to be of practical use. This article presents a critical synthesis of ideas from each of these areas and interprets them in terms of design requirements for computer-based models being developed to provide scientific information support for policy and planning. Illustrative examples are given from the field of freshwater resources management. Although computer-based diagramming and modeling tools can facilitate processes of dialogue, they lack adequate simulation capabilities. Component-based models and modeling frameworks provide such functionality and may be suited to supporting problematic or messy decision contexts. However, significant technical (implementation) and socio-technical (use) challenges need to be addressed before such ambition can be realized.