Rethinking the contribution of indigenous management in small-scale water provision among selected rural communities in Cameroon

This paper describes the pro-active role of rural communities in negotiating livelihood and sustenance through the improvement of some of their local water sources. It discusses the strategies put in place to ensure the availability of water, one of the world’s scarcest natural resources. Despite some external assistance, local communities are increasingly shouldering the responsibility of ensuring the availability of water through self-reliant efforts. These attempts are being undermined by a high incidence of waterborne and water-related diseases, which are impacting on health, and hygiene and other health care delivery systems. The management of potable water is proving to be a herculean task for most communities after the departure of funding partners. To guarantee the proper maintenance of pipe borne water schemes, communities are rethinking their strategies as they grapple with difficulties to put in place viable techniques for sustainability of water supply schemes.     

AN ALGORITHM FOR ESTIMATING SURFACE SUSPENDED SEDIMENT CONCENTRATIONS WITH LANDSAT MSS DIGITAL DATA1

ABSTRACT: Algorithms for Landsat MSS digital data are needed to reduce the necessity of calibrating each Landsat scene if these data are to be useful in monitoring programs for surface suspended sediments. In this study digital data were extracted from 16 Landsat Multispectral Scanner (MSS) scenes collected between March 1987 and August 1988 over Enid Reservoir in North Central Mississippi. These data were converted to radiance and reflectance data for comparison with field measurements of surface suspended sediment concentrations. Concentrations ranged from 2 to 168 mg/1 during the study with only four greater than 100 mg/l. Linear and polynomial regression analyses were used to relate the surface suspended sediment concentrations with radiance and reflectance. Reflectance in MSS band 2 (0.6 to 0.7 μm) and MSS band 3 (0.7 to 0.8 μm) were best related to the surface suspended sediment concentrations with coefficients of determination accounting for 71 percent and 68 percent of the variation in the data, respectively. Regressions with radiance data accounted for 36 percent (band 2) or less of the variation. Logarithmic transformations of either reflectance or sediment concentrations increase the coefficients of determination for MSS band 2 reflectance data to 81 percent. Regressions between the ratio of MSS band 1 to MSS band 2 reflectances and concentrations also accounted for 80 percent of the variation. An equation Log_e SS (mg/l) = 9.21R½+ 2.71R½2 + 8.45, where S is surface suspended sediment concentrations and R¹/₂ is the ratio of MSS band 1 to MSS band 2 reflectances, provided the best fit to the data with a coefficient of determination of 0.82. This equation is essentially the same as an algorithm proposed by Topliss et at. (1990), for estimating surface suspended sediment concentrations in Canadian coastal waters. These equations for Enid Reservoir and Canadian waters suggest that it may be possible to develop an algorithm for widespread use for estimating surface suspended sediments.     

THE POTENTIAL EFFECTS OF GLOBAL WARMING ON THE PRIMARY PRODUCTIVITY OF A SUBALPINE LAKE1

ABSTRACT Atmospheric scientists have predicted that large-scale climatic changes will result from increasing levels of tropospheric CO₂ We have investigated the potential effects of climate change on the primary productivity of Castle Lake, a mountain lake in Northern California. Annual algal productivity was modeled empirically using 25 years of limnological data in order to establish predictive relationships between productivity and the climatic variables of accumulated snow depth and precipitation. The outputs of monthly temperature and precipitation from three general circulation models (GCMs) of doubled atmospheric CO₂ were then used in the regression model to predict annual algal productivity. In all cases, the GCM scenarios predicted increased algal productivity for Castle Lake under cenditions of doubled atmospheric CO₂The primary cause of enhanced productivity was the increased length of the growing season resulting from earlier spring ice-out.     

Implications of environmental program planning for siting a nuclear waste repository at Yucca Mountain,Nevada, USA

The US Department of Energy (DOE) plans to conduct site characterization studies at Yucca Mountain, Nevada, to determine if the location is a suitable site for a nuclear waste repository. In lieu of traditional environmental review in accordance with the National Environmental Policy Act of 1969, the DOE is relying on an environmental assessment (EA) mandated by the Nuclear Waste Policy Act of 1982 as the cornerstone of its environmental program for the Yucca Mountain Project. Because of statutory restrictions, the EA is not based on comprehensive baseline information. Neither does it address fundamentals of environmental analysis such as ecological integrity and assessment of cumulative impacts. Consequently, the present environmental program for Yucca Mountain reflects decisions made without complete information and integrated environmental review. The shortcomings of the program risk compromising the natural integrity of Yucca Mountain and invalidating future assessment of the ability of a nuclear waste repository located at the site to protect the environment. Significant improvements are needed in the repository siting program before it can serve as a model of how society can evaluate the long-term environmental consequences of advanced technologies, as has been suggested.     

Optimizing carbon sequestration in commercial forests by integrating carbon management objectives in wood supply modeling

This paper provides a methodology for generating forest management plans, which explicitly maximize carbon (C) sequestration at the forest-landscape level. This paper takes advantage of concepts first presented in a paper by Meng et al. (2003; Mitigation Adaptation Strategies Global Change 8:371–403) by integrating C-sequestration objective functions in existing wood supply models. Carbon-stock calculations performed in Woodstock^TM (RemSoft Inc.) are based on C yields generated from volume table data obtained from local Forest Development Survey plots and a series of wood volume-to-C content conversion factors specified in von Mirbach (2000). The approach is used to investigate the impact of three demonstration forest-management scenarios on the C budget in a 110,000 ha forest in south-central New Brunswick, Canada. Explicit demonstration scenarios addressed include (1) maximizing timber extraction either by clearcut or selection harvesting for greatest revenue generation, (2) maximizing total C storage in the forest landscape and in wood products generated from harvesting, and (3) maximizing C storage together with revenue generation. The level of clearcut harvesting was greatest for scenario 1 (≥15 × 10⁴ m³ of wood and ≥943 ha of land per harvesting period), and least for scenario 2 (=0 m³ per harvesting period) where selection harvesting dominated. Because softwood saw logs were worth more than pulpwood ($60 m⁻³ vs. $40 m⁻³) and were strategic to the long-term storage of C, the production of softwood saw logs exceeded the production of pulpwood in all scenarios. Selection harvesting was generally the preferred harvesting method across scenarios. Only in scenario 1 did levels of clearcut harvesting occasionally exceed those of selection harvesting, mainly in the removal of old, dilapidated stands early in the simulation (i.e., during periods 1 through 3). Scenario 2 provided the greatest total C-storage increase over 80 years (i.e., 14 × 10⁶ Mg C, or roughly 264 Mg ha⁻¹) at a cost of $111 per Mg C due to lost revenues. Scenarios 3 and 1 produced reduced storage rates of roughly 9 × 10⁶ Mg C and 3 × 10⁶ Mg C, respectively; about 64% and 22% of the total, 80-year C storage calculated in scenario 2. The bulk of the C in scenario 2 was stored in the forest, amounting to about 76% of the total C sequestered.     

Food webs supporting fish over subtropical mudflats are based on transported organic matter not in situ microalgae

We present here a morpho-functional and behavioural study of the feeding adaptations developed by a deep-sea invertebrate, the caprellid amphipod Parvipalpus major, in an environment temporarily deprived of external food supply. The animals were taken intact from bathyal muddy sediments using a classic Barnett multi-tub corer at depths ranging from 424 to 761 m. They were transferred to the laboratory, kept in tanks with their native sediment at a constant temperature (10°C) and their behaviour was studied by video analysis. Their morphology consists of elongated somites, with pereopods 5–7 ending in elongated curved dactyls, which are longer than those of more coastal species. Analysis of the literature shows that the largest caprellids inhabit the deepest and muddiest zones. This particular morpho-functional adaptation enables the species to adopt an originally erect and steady stance by fixing onto soft muddy sediment, thus improving its ability to prospect for food in its surrounding environment. For the most part, P. major balances its body at its anchorage point as it searches for food in the water column, but occasionally it bends down to the substrate, and tosses some sediment into the water column. Food is then selected from the particles that float down. Presumably, after exhausting the food supply in one area, the animal jumps into the water column and moves about a body length further on. This would appear to be an original strategy for foraging larger areas of organic matter from fixed, but temporary, positions. Finally, we show that caprellids are able to practise coprophagy. To conclude, we suggest that there is a positive correlation between body elongation and depth, with improved anchoring and coprophagy being an optimal way to conserve energy in conditions of limited diet and improve adaptation to life on deep-sea muddy bottoms.Communicated by S.A. Poulet, Roscoff     

Isolation and 16S DNA characterization of soil microorganisms from tropical soils capable of utilizing the herbicides hexazinone and tebuthiuron

Six non-fermentative bacteria were isolated from Colombian (South America) and Hawaiian (USA) soils after enrichment with minimal medium supplemented with two herbicides, hexazinone (Hex) and tebuthiuron (Teb). Microscopic examination and physiological tests were followed by partial 16S DNA sequence analysis, using the first 527 bp of the 16S rRNA gene for bacterial identification. The isolated microorganisms (and in brackets, the herbicide that each degraded) were identified as: from Colombia. Methylobacterium organophilum [Teb], Paenibacillus pabuli [Teb], and Micrmbacterium foliorum [Hex]; and from Hawaii, Methylobacterium radiotolerans [Teb], Paenibacillus illinoisensis [Hex], and Rhodococcus equi [Hex]. The findings further explain how these herbicides, which have potential for illicit coca (Erythroxylum sp.) control, dissipate following their application to tropical soils.     

Measurement of 13C/12C of chloroacetic acids by gas chromatography/combustion/isotope ratio mass spectrometry

This paper describes a novel analytical methodology using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to measure the 13C/12C ratios of chloroacetic acids (CAAs). CAAs are a major class of environmental pollutants that are widely distributed throughout the world, often at relatively high concentrations, and are of concern due to their toxic effects, particularly on plants. The 13C/12C of CAA reagents was measured by IRMS subsequent to offline combustion. Aqueous solutions of these CAAs were derivatized to the corresponding methyl chloroacetates (MCAAs) with acidic methanol with a known isotopic composition, extracted into pentane, and analyzed by GC/C/IRMS. Measured 13C/12C ratios of derivatized MCAAs were in agreement with calculated values within 1 per thousand for monochloroacetic acid and trichloroacetic acid and within 2 per thousand for dichloroacetic acid, suggesting that methylation and other analytical methodology steps do not isotopically fractionate derivatized MCAAs. 13C/12C ratios of reagent CAAs from different sources had varying isotopic signatures suggesting differences in source carbon and/or production methods. Our results underscore the potential of stable isotopes to serve as tracers of environmental sources of CAAs.     

A new environmental chamber for evaluation of gas-phase chemical mechanisms and secondary aerosol formation

A new state-of-the-art indoor environmental chamber facility for the study of atmospheric processes leading to the formation of ozone and secondary organic aerosol (SOA) has been constructed and characterized. The chamber is designed for atmospheric chemical mechanism evaluation at low reactant concentrations under well-controlled environmental conditions. It consists of two collapsible 90 m³ FEP Teflon film reactors on pressure-controlled moveable frameworks inside a temperature-controlled enclosure flushed with purified air. Solar radiation is simulated with either a 200 kW Argon arc lamp or multiple blacklamps. Results of initial characterization experiments, all carried out at 300–305 K under dry conditions, concerning NO_x and formaldehyde offgasing, radical sources, particle loss rates, and background PM formation are described. Results of initial single organic–NO_x and simplified ambient surrogate–NO_x experiments to demonstrate the utility of the facility for mechanism evaluation under low NO_x conditions are summarized and compared with the predictions of the SAPRC-99 chemical mechanism. Overall, the results of the initial characterization and evaluation indicate that this new environmental chamber can provide high quality mechanism evaluation data for experiments with NO_x levels as low as 2 ppb, though the results indicate some problems with the gas-phase mechanism that need further study. Initial evaluation experiments for SOA formation, also carried out under dry conditions, indicate that the chamber can provide high quality secondary aerosol formation data at relatively low hydrocarbon concentrations.