The environmental impact of a chloro-alkali factory in a river basin in Eastern India

Summary It has been established that the electrodes of the dialyser in a chloro-alkali plant in Eastern India release mercury beyond the permissible limits into the River Koel. Mercury in elemental form, as well as certain organo-mercury compounds, including methyl mercury, have been detected at a distance of 25 km from the discharge point. Even at a distance of 5–10 km, the mercury content of the sediment may be as high as 0.6–3.2 mg kg^–1 above the value of sediment upstream of the plant. This sediment itself is contaminated, probably by battery and paint factories, etc., still further upstream. Thus, the chloro-alkali factory has contributed 60–320 times above the permissible limit (0.01 mg kg^–1) of mercury release, at a distance of 5–10 km from the point of release. Furthermore, various phytoplankton and zooplankton have been contaminated, leading to very high mercury contents in certain fish. This food chain, therefore, threatens man himself.Dr Sajalendu Nanda is currently a Research Associate at Bangur Institute of Neurology in Calcutta. He possesses an MSc in Environmental Biology and a PhD in Ecology. His address for correspondence is c/o Dr P.K. Tapaswi, Professor-in-Charge at the Biological Sciences Division of the Indian Statistical Institute.     

Efficiency of a protected-area network in a Mediterranean region: a multispecies assessment with raptors

Three different systems of designating protected areas in a Mediterranean region in southeastern Spain were studied, referring to their effectiveness and efficiency for protecting both the breeding territories and the suitable habitat of a set of ten raptor species. Taking into consideration the varying degrees of endangerment of these species, a map of multispecies conservation values was also drawn up and superimposed on the three protected-area systems studied. In order to compare the levels of protection afforded by the three systems, we considered two indices that measured their relative effectiveness and efficiency. The effectiveness estimated the proportion of territories or optimal habitat protected by the networks while efficiency implicitly considered the area of each system (percentage of breeding territories or optimal habitat protected per 1% of land protected). Overall, our results showed that the most efficient system was that formed by the set of regional parks and reserves (17 protected breeding territories per 100 km²), although, given its small total area, it was by far the least effective (only protecting the 21% of the breeding territories of all species and 17% of the area of high conservation value). The systems formed by the Special Protection Areas (designated under the EU “Birds Directive”) and by the Special Conservation Areas (designated under the EU “Habitats Directive”) notably increased the percentages of protected territories of all species (61%) and area of high conservation value (57%), but their efficiency was not as high as expected in most cases. The overall level of protection was high for all species except for the Lesser Kestrel (Falco naumanni), an endangered falcon that inhabits pseudo-steppe and traditional agricultural habitats, which are clearly underrepresented in the protected-area network of the study region.     

Reductive dechlorination of tetrachloroethene in a sand reactor using a potentiostat

In this study, an electrochemical system was investigated to enhance abiotic dechlorination of chlorinated solvents in contaminated soil in situ. A potentiostatic electrolysis sand reactor was developed and tested to evaluate tetrachloroethene (PCE) dechlorination in saturated sand. When operated with recirculating nutrient-supplemented water the reactor sustained a low oxidation reduction potential (ORP) at the cathode (<-400 mV standard hydrogen electrode [SHE]), a pH less than 9.4, and electric current >5 mA at room temperature with the cathodic potential controlled at -950 mV SHE. Tetrachloroethene in the electrolysis reactor had a half-life of 6.8 d compared with the control bioreactor without electrolysis, which had a PCE half-life of 16.4 d. Ethane and ethene were the main dechlorination products in the test reactor, while trichloroethene (TCE) accumulated in the nutrient-amended control reactor without electrolysis. An electrolysis reactor operated with water not amended with nutrients showed a PCE half-life of 7.6 d, suggesting that most of dechlorination activity in the reactor was abiotic. Since complete dechlorination can be achieved under moderate pH and temperature, this type of electrolysis technology is attractive as a remedial method for subsurface chloroethene contamination.     

Changes in a reach of a northern California stream following wildfire

One reach of a northern California stream, burned by intense wildfire in 1979, was studied to monitor changes and recovery from the fire. Benthic macroinvertebrates collected three weeks and one to four, six, eight, and 11 years following the wildfire were used to assess stream condition and compared to samples from a reach of a nearby unburned stream. Transportable sediment was measured 11 years following the fire. The fire was also used as a worst case example to compare results with a standard cumulative watershed effects assessment methodology. Benthic invertebrate density and taxa richness of the burned reach were both low compared to the unburned reach three weeks after the fire. Mean density was significantly higher in the burned reach in the three years following the fire, while taxa richness was significantly lower in the burned reach over the same time period. Higher density and lower richness in the burned reaches persisted throughout the study period but were not significant after three years. Mean Shannon diversity of the burned reach was significantly lower than that of the unburned reach for each year of the study, although absolute differences diminished throughout the 11-year study period. Transportable sediment was significantly higher in the burned reach than the unburned comparison. Pearson correlations between sediment and biological metrics were weak. Although the correlation between invertebrate diversity and a measure of watershed disturbance (equivalent roaded acres) was high (r=0.95) for the burned watershed, the measure appeared to be a poor indicator of cumulative effects on stream condition. The measure (ERA) was poorly correlated with invertebrate diversity in the unburned reach and, while the ERA calculations indicated substantial recovery, biological and physical measures indicated recovery of the burned stream reach was incomplete.     

Development of a Commodity-by-industry Economic-Ecological Model of Water Demand in a Rural Economy

The main objective of this paper is to develop a commodity-by-industry economic-ecological model (CIEEM) based on data collected in a rural village in Nigeria and to assess its utility for measuring the implication of various economic activities on the demand for scarce water resources. Our primary concern is model construction and determination of the direct and total requirements of both economic commodities (inter-industry transactions) and ecological commodities (water, land and vegetation) used in the economy. Also considered is the discharge of ecological commodities (waste water and solid wastes) back to the environment. Results show that, despite sparse sectoral interdependence within the economic system, inputs and outputs of ecological commodities include significant indirect components that can only be captured in an input-output framework. The most intensive users of water based on the direct effects are animal husbandry, construction and irrigated agriculture; based on total effects they are catering/trading, construction and animal husbandry, in descending order.     

Experiences from a Community Nature Project in a Housing Estate in Singapore

A city farm concept called the Nature Corner project, which involves both animals and plants, was initiated in Ghim Moh housing estate, Singapore, in 1997. The objectives of the community project were to introduce nature to residents and to encourage social interaction. The paper analyses the project's set-up, assesses the funding, maintenance and other issues involved and discusses the findings of a 1998 sample survey of users and non-users of the project. It was found from the survey that the project has been quite successful in introducing nature to users but less successful in encouraging social interaction among them.     

Experiences from a Community Nature Project in a Housing Estate in Singapore

A city farm concept called the Nature Corner project, which involves both animals and plants, was initiated in Ghim Moh housing estate, Singapore, in 1997. The objectives of the community project were to introduce nature to residents and to encourage social interaction. The paper analyses the project's set-up, assesses the funding, maintenance and other issues involved and discusses the findings of a 1998 sample survey of users and non-users of the project. It was found from the survey that the project has been quite successful in introducing nature to users but less successful in encouraging social interaction among them.     

Development of a framework to implement a recycling program in an elementary school

This study developed a system to plan, evaluate, implement, and monitor a waste reduction and source-separation program, which was then tested through a field study in a New York City elementary school. Despite efforts to implement integrated waste management in elementary schools, appropriate planning tools that document performance and support program development are lacking. To fill this gap, a system for analyzing existing programs was developed. After identifying the phases required for a successful program, a scoring system was developed to quantify the performance of existing programs. To assess existing protocol, recommendations from leading municipalities were reviewed, and the performance of existing programs was quantified within the scoring system. The existing protocol was found to contain similarities, but an overarching approach was needed to connect the provisions with programs that have been successfully deployed. From this analysis, a scoring system was developed to take into consideration the major elements needed for a waste reduction and source-separation plan, colloquially referred to as a recycling plan, as well as the specifics of implementation. This system allows for the review of programs already developed, and can pinpoint limitations prior to implementation. The framework was evaluated through the test case school, with both waste audit data and diagrams. From the lessons learned, successful techniques and recommendations for utilizing this framework were created.     

石油类在河流中自净能力的研究

根据河流的特点,利用示踪剂对河流中石油类污染物的衰减情况进行了分析,建立了污染物扩散模式,确定了河流不同断面的石油通量,求出了石油类污染物的衰减系数。为污染物的排放量和河流环境容量的确定提供了保证。     

Biogeochemistry of fluoride in a plant-solution system

Fluoride (F-) pollutants can harm plants and the animals feeding on them. However, it is largely unknown how complexing and chelating agents affect F bioavailability. Two studies were conducted that measured F- bioavailability and uptake by rice (Oryza sativa L.). In the first study, rice was grown in solution culture (pH 5.0) with 0, 2, or 4 mM F- as KF to compare the interaction of F- with humic acid (HA) and with a conventional chelating agent, N-hydroxyethylenthylenediaminetriacetic acid (HEDTA). In the second study, F was supplied at 0, 0.5, 1.0, and 2.0 mM KF with an additional 2 mM F- treatment containing solution Ca at 2x (2 mM Ca) the level used in the first study, to test the effect added Ca had on F- availability and uptake. Total biomass was greatest with HEDTA and F- < 1 mM. Leaf and stem F concentrations increased exponentially as solution F- increased linearly, with nearly no F partitioning into the seed. Results suggest that F was taken up as HF0 while F- uptake was likely restricted. Additionally, F- competed with HA for Ca, thus preventing the formation of Ca-HA flocculents. The addition of soluble Ca resulted in the precipitation of CaF2 solids on the root surface, as determined by tissue analysis and energy dispersive X-ray spectroscopy.     

Impact of mercury on the activity pattern of a marker enzyme in a freshwater bivalve

Sessile benthic organisms are universally accepted as bio-indicators of environmental pollution and lysosomal membrane is often the target of injury by xenobiotics resulting in destabilization. Effect of mercury on the activity pattern of the marker enzyme, Acid Phosphatase in the gill and hepatopancreas of the freshwater mussel, Lamellidens corrianus (Lea) at 24, 72, and 168 h, post-exposure discussed. ACP activity was determined as given in Sigma Technical Bulletin (No. 104) and μmol of p-nitrophenol liberated/mg protein/h calculated. The work aimed to study the duration of exposure and concentration of the metal influence, the direction of the response of the enzyme in the two tissues studied and results show that the concentration of the metal as well as the period of exposure do influence the enzyme activity and may have predictive value as a biomarker of impending population changes. Higher concentration of the metal is assumed to have induced stress proteins like metallothioneins.     

A phenomenographical approach to the study of pre-adolescents' use of maps in a wayfinding exercise in a suburban environment

This paper reports the investigative study, which used a phenomenographical approach, on how a group of 12-year-old students found their way around a designated suburban route by referring to a sequential listing of streets along the route and a street directory map of the suburban area. While the content of this study belongs to map use and wayfinding experience of the pre-adolescent students, the approach used is phenomenographic in that it identified the qualitatively different ways that the students experienced the suburban environment. The students' experiences were interpreted using a behaviourial matrix of their actions while they traversed the route. Qualitative variations in their approaches to wayfinding using maps were obtained from interviews which were conducted immediately after the students completed their route navigation. Four qualitatively different approaches were determined from their reflections of their own wayfinding behaviours. They are the restricted and neophytic approach; careful and sequential approach; deductive and familiarized approach; and the visualized and co-ordinated spatial approach. These approaches reflect the different behaviours and abilities of the students to: plan their route using a street directory map; plan the route street by street or a number of streets at a time; use street signs and other landmarks during the actual task; utilize local knowledge of the route; maintain their orientation; visualize spatial patterns; and use the scale on the map to help planning.     

Design and Performance of a Channel Reconstruction Project in a Coastal California Gravel-Bed Stream

A 0.9 km-reach of Uvas Creek, California, was reconstructed as a sinuous, meandering channel in November 1995. In February 1996, this new channel washed out. We reviewed project documents to determine the basis for the project design and conducted our own historical geomorphological study to understand the processes operating in the catchment and project reach. The project was designed using a popular stream classification system, based on which the designers assumed that a "C4" channel (a meandering gravel-bed channel) would be stable at the site. Our historical geomorphological analysis showed that the reach had been braided historically, typical of streams draining the Franciscan Formation in the California Coast Ranges, with episodic flows and high sand and gravel transport. After the project washed out, Uvas Creek reestablished an irregular, braided sand-and-gravel channel, although the channel here was narrower than it had been historically, probably due to such factors as incision caused by gravel mining. Our study casts doubt on several assumptions common in many stream restoration projects: that channel stability is always an appropriate goal; that channel forms are determined by flows with return periods of about 1.5 years; that a channel classification system is an easy, appropriate basis for channel design; and that a new channel form can be imposed without addressing the processes that determine channel form.     

Denitrification as a nitrogen removal mechanism in a Vermont peatland

Atmospheric deposition of nitrogenous compounds to ombrotrophic peatlands (i.e., those that have peat layers higher than their surroundings and receive nutrients and minerals exclusively by precipitation) has the potential to significantly alter ecosystem functioning. This study utilized the acetylene inhibition technique to estimate the relative importance of denitrification in nitrogen removal from a primarily ombrotrophic peatland, in an attempt to estimate the threat of increased nitrogen loadings to these areas. Estimates of mean rates of denitrification ranged from -2.76 to 84.0 ng N(2)O-N cm(-3) h(-1) (equivalent to -150 to 4800 microg N(2)O-N m(-2) h(-1)) using an ex situ core technique and from -8.30 to 5.98 microg N(2)O-N m(-2) h(-1) using an in situ chamber technique. Core rates may have been elevated over natural field levels due to effects of disturbance on substrate availability, and chamber rates may have been low due to diffusional constraints on acetylene and N(2)O. Net nitrification was also measured in an attempt to evaluate this process as a source of nitrate for denitrifiers. The low rates of net nitrification measured, in combination with the low rates of in situ denitrification and the very low amounts of free nitrate measured in this peatland, suggests that inorganic N turnover in this wetland is low. Results showed that nitrate was a limiting factor for denitrification in this peatland, with mean rates from nitrate-amended cores ranging from 13.1 to 260 ng N(2)O-N cm(-3) h(-1), and it is expected that increases in nitrogen loadings will increase denitrification rates in this ecosystem.     

Sediment delivery linkages in a chaparral watershed following a wildfire

The purpose of this research is to study the temporal and spatial sediment delivery to and within the stream network following a wildfire on a chaparral watershed in Arizona, USA. Methods include interpretation of channel processes (aggradation, degradation) from sequential aerial photographs, field measurements of sediment delivery, and overland flow from ten microwatersheds having different vegetation cover (no vegetation, chaparral cover, and bare with vegetation buffer strips). The response of the watershed to the fire was very complex. The fire reduced the chaparral cover to zero in most locations and severe erosion led to filling of the channels by sediment. With vegetation recovery, sediment delivery from the watershed practically ceased. Vegetation buffer strips were mainly responsible for arresting the sediment delivered from bare hillslopes. Relatively clear water, entering the channels, caused degradation in the tributaries that delivered the sediment into the main stream at El Oso Creek. Due to high water infiltration by immense volumes of sediment deposits in the middle reach, the sediment from the tributaries was deposited as in-channel fans. In contrast, the upper reach of El Oso Creek behaved similarly to the tributaries. It aggraded after the fire and was followed by degradation. The low reach of El Oso Creek is degrading because it is still adjusting base level to the incision of the master stream. Implications of this study are that land managers, concerned to avoid severe erosion and sedimentation following disturbance, should concentrate on the establishment and enhancement of vegetation buffer strips along channel banks.     

Assessment of Tree Rings as a Hydrologic Record in a Humid Subtropical Environment1

Crockett, Kris, Jonathan B. Martin, Henri D. Grissino-Mayer, Evan R. Larson, and Thomas Mirti, 2010. Assessment of Tree Rings as a Hydrologic Record in a Humid Subtropical Environment. Journal of the American Water Resources Association (JAWRA) 1-13. DOI: 10.1111/j.1752-1688.2010.00464.x Abstract: Information about long-term variability of streamflow is important to allocate water resources, but few historical records extend more than 75 years into the past, requiring proxy records to evaluate flow prior to that time. Flow proxies have been found in tree-ring widths in temperate regions, but have rarely been used in humid subtropical environments because the relationship between tree growth and climate was believed to be weakened by limited seasonality and stress on tree growth from drought conditions. Tree-ring residual chronologies from two forests sampled from northern Florida correlate well with historical annual discharge (r² values as high as 0.47) from 3 of 15 river-gauging stations that were used to compare with the tree-ring chronologies. The best correlations occur where streamflow has little contribution from spring discharge or continuous flow from lakes and wetlands. Streams lack correlations with the tree-ring residual chronologies (r² values as low as 0.0002) where springs and continuous discharge from lakes mute variations in their flow. Tree-ring chronologies appear to be useful for reconstruction of prehistorical variations of some streamflow in humid subtropical regions, but interpretations of the reconstructions must consider the local hydrologic conditions.     

Farming in the urban environment of a developing nation — a case study from Ibadan metropolis in Nigeria

Summary The major characteristics, problems and prospects of farming in an urban environment of a developing nation are investigated using the Ibadan metropolitan area of Nigeria as a case study. Eight hundred farmers, made up of both part-time and full-time farmers were interviewed in five urban fringe settlements in the study area. Findings revealed that farming in the urban environment is guided by the logic of survival since most of the farmers engaged in urban cultivation are mainly low-income earners and they farm mainly to reduce their expenses on food and to supplement the family's income. The major problem confronting farming in the area is competition from non-agricultural land uses. Nevertheless, more than half (50.5 percent) of the farmers, who had been approached to sell their farmlands for non-agricultural uses in the area, rejected the offer, indicating that the prospects of continued farming are thought to be good. Measures like the sale of urban land at its agricultural value, provided the land remains in cultivation, as well as the further provision of land in and around the farmers' working places, could improve their access to land for extended farming.Dr Adeniyi Gbadegesin is a lecturer in the Department of Geography at the University of Ibadan. He has published papers widely on agricultural topics.     

Mechanisms of thorium migration in a semiarid soil

Thorium concentrations at Kirtland Air Force Base training sites in Albuquerque, NM, have been previously described; however, the mechanisms of thorium migration were not fully understood. This work describes the processes affecting thorium mobility in this semiarid soil, which has implications for future remedial action. Aqueous extraction and filtration experiments have demonstrated the colloidal nature of thorium in the soil, due in part to the low solubility of thorium oxide. Colloidal material was defined as that removed by a 0.22-microm or smaller filter after being filtered to nominally dissolved size (0.45 microm). Additionally, association of thorium with natural organic matter is suggested by micro- and ultrafiltration methods, and electrokinetic data, which indicate thorium migration as a negatively charged particle or anionic complex with organic matter. Soil fractionation and digestion experiments show a bimodal distribution of thorium in the largest and smallest size fractions, most likely associated with detrital plant material and inorganic oxide particles, respectively. Plant uptake studies suggest this could also be a mode of thorium migration as plants grown in thorium-containing soil had a higher thorium concentration than those in control soils. Soil erosion laboratory experiments with wind and surface water overflow were performed to determine bulk soil material movement as a possible mechanism of mobility. Information from these experiments is being used to determine viable soil stabilization techniques at the site to maintain a usable training facility with minimal environmental impact.     

Fate of prions in soil: a review

Prions are the etiological agents of transmissible spongiform encephalopathies (TSSEs), a class of fatal neurodegenerative diseases affecting humans and other mammals. The pathogenic prion protein is a misfolded form of the host-encoded prion protein and represents the predominant, if not sole, component of the infectious agent. Environmental routes of TSE transmission areimplicated in epizootics of sheep scrapie and chronic wasting disease (CWD) of deer, elk, and moose. Soil represents a plausible environmental reservoir of scrapie and CWD agents, which can persist in the environment for years. Attachment to soil particles likely influences the persistence and infectivity of prions in the environment. Effective methods to inactivate TSE agents in soil are currently lacking, and the effects of natural degradation mechanisms on TSE infectivity are largely unknown. An improved understanding of the processes affecting the mobility, persistence, and bioaviailability of prions in soil is needed for the management of TSE-contaminated environments.