Patchy distributions: Optimising sample size

A method for estimating sample size which does not require an a priori definition of desired precision, or the assumption that the population is normally distributed with constant variance, has recently been proposed. This paper discusses this method and presents five modifications which make the method easier to use and reduce the probability of estimating a larger sample size than is actually required. The method is extended and used to estimate the mean abundance of patchily distributed benthic organisms. The technique can be used to guide the design of any environmental sampling programme, be it physical, chemical or biological, where comparisons between times and/or locations are required. Trade-offs between numbers of replicates and numbers of levels/sites are discussed.     

Assessing land use impacts on flood processes in complex terrain by using GIS and modeling approach

A distributed hydrologic modeling and GIS approach is applied for the assessment of land use impact in the Steinsel sub-basin, Alzette, Grand-Duchy of Luxembourg. The assessment focuses on the runoff contributions from different land use classes and the potential impact of land use changes on runoff generation. The results show that the direct runoff from urban areas is dominant for a flood event compared with runoff from other land use areas in this catchment, and tends to increase for small floods and for the dry season floods, whereas the interflow from forested, pasture and agricultural field areas contributes to the recession flow. Significant variations in flood volume, peak discharge, time to the peak, etc., are found from the model simulation based on the three hypothetical land use change scenarios.     

Sampling Benthic Macroinvertebrates in a Large Flood-Plain River: Considerations of Study Design, Sample Size, and Cost

Estimation of benthic macroinvertebrate populations over large spatial scales is difficult due to the high variability in abundance and the cost of sample processing and taxonomic analysis. To determine a cost-effective, statistically powerful sample design, we conducted an exploratory study of the spatial variation of benthic macroinvertebrates in a 37 km reach of the Upper Mississippi River. We sampled benthos at 36 sites within each of two strata, contiguous backwater and channel border. Three standard ponar (525 cm²) grab samples were obtained at each site ('Original Design'). Analysis of variance and sampling cost of strata-wide estimates for abundance of Oligochaeta, Chironomidae, and total invertebrates showed that only one ponar sample per site ('Reduced Design') yielded essentially the same abundance estimates as the Original Design, while reducing the overall cost by 63%. A posteriori statistical power analysis ( = 0.05, = 0.20) on the Reduced Design estimated that at least 18 sites per stratum were needed to detect differences in mean abundance between contiguous backwater and channel border areas for Oligochaeta, Chironomidae, and total invertebrates. Statistical power was nearly identical for the three taxonomic groups. The abundances of several taxa of concern (e.g., Hexagenia mayflies and Musculium fingernail clams) were too spatially variable to estimate power with our method. Resampling simulations indicated that to achieve adequate sampling precision for Oligochaeta, at least 36 sample sites per stratum would be required, whereas a sampling precision of 0.2 would not be attained with any sample size for Hexagenia in channel border areas, or Chironomidae and Musculium in both strata given the variance structure of the original samples. Community-wide diversity indices (Brillouin and 1-Simpsons) increased as sample area per site increased. The backwater area had higher diversity than the channel border area. The number of sampling sites required to sample benthic macroinvertebrates during our sampling period depended on the study objective and ranged from 18 to more than 40 sites per stratum. No single sampling regime would efficiently and adequately sample all components of the macroinvertebrate community.     

Background Levels of Metals in Soils, McMurdo Station, Antarctica

McMurdo Station is the largest research station in Antarctica, with a population that ranges each year from 250 to 1200 people. Because of its size and 40-year history of use, a number of locations around the station have become contaminated with wastes. Soils and sediments in these areas have been shown to contain elevated levels of petroleum-related products, PCBs, other organics, and metals. While some remedial investigations have been conducted, background levels of metals in soils have not been determined. This paper reports on background levels of metals in a natural basalt-derived soil (gray soil) and scoria (soft porous rock used as fill, red soil) near McMurdo Station using two fundamentally different analytical procedures, concentrated acid extraction/analysis and total metals. These data facilitate determining the extent and levels of metal contamination near McMurdo Station and provide reference levels of metals for comparison with existing and future remediation data. There were statistically significant differences between metals concentrations in both gray and red soils, and no correlations between the level of extracted versus total metal. Generally, only a small fraction of a metal was extractable.     

Flue gas treatability studies: a tool for techno-economic control of industrial air pollution

Air pollution problems in developing countries have gained larger fraction in the last decade especially due to non functioning and non implementation of effective air pollutioncontrol devices in industries. In industrial wastewater management, adequate treatability studies are conducted to arrive at a techno-economic treatment option. However no suchstudies were done for reducing air pollution or emission fromindustries until now in India. Little information was availableabout such studies in other countries. This article provides information about a novel technique known asflue gas treatability studies and to undertake such studies, a pilot scale system is installed in Air Pollution Control Divisionof M/s National Environmental Engineering research Institute, NEERI, Nagpur-20, India. This study is a tool for techno-economicselection of air pollution control systems specially for small/medium scale industrial emissions.     

Planning Tools for Developing Comprehensive Regional Monitoring Programs

We present a planning framework that structures thelarge amount of interrelated information involved indeveloping regional monitoring programs. By regionalwe mean programs that recognize the importance ofprocesses that occur on larger geographic scales andthat cut across more than one ecosystem component. Theframework helps visualize functional relationshipsamong qualitative ingredients such as public concernsand more concrete details such as individual dataelements. It portrays the flow of information amongthe components of a regional program and ties eachaspect of the program to management decision-makingneeds. This makes it easier, during the planningprocess, to ensure that monitoring will actuallyproduce useful information. Further, the frameworksnovel, graphically oriented, and readily accessibleformat makes key information equally available to thewide range of participants (regulators, scientists,managers, public) whose input and support arenecessary for program success.     

Effects of acid rain on growth and nutrient concentrations in Scots pine and Norway spruce seedlings grown in a nutrient-rich soil

The effects of artificially applied acid precipitation on growth and nutrient concentrations of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst.) seedlings were investigated in a long-term acid irrigation experiment in field conditions. Seedlings of northern and southern origin were planted in boxes containing peat and composted soil rich in nutrients, and sprinkler irrigated with water acidified with nitric and sulphuric acids to pH 3 or pH 4 for periods varying from two to three and a half growing seasons during 1986-1989. Water irrigated (pH 5.4-7.6) and non-irrigated groups of seedlings were also included in the experiment. At the end of the experiment needles, main and lateral shoots and roots were collected from the seedlings for the determination of height growth and biomass partitioning, and for the analysis of S, N, Mg, P, K, Ca, Mn and Fe concentrations. The treatment effects compared to the irrigated control were studied using multivariate analyses of variance and covariance. In the pine seedlings the total dry matter production increased by 25-70% compared with the irrigated controls when the total wet deposition to the seedlings exceeded 67 kg S ha(-1) and 36 kg N ha(-1) (e.g. after two growing seasons' exposure of the pH 3 treatment). The increase was mainly due to an increase in needle dry weight (54-72% greater at pH 3) and root weight (20-65% greater at pH 3), whereas the height growth or shoot weight growth were less affected. The northern provenance pine seedlings responded more clearly to the pH 3 irrigation than the southern ones. The treatments had no consistent effects on any of the growth variables studied in the spruce seedlings, however. The pines had higher root and foliage Ca concentrations as a result of the acid irrigation, whereas in spruce, acid rain decreased the Ca concentration in needles and shoots. Root Mn and Fe concentrations were higher in both species as a result of the pH 3 treatment. A higher soil conductivity and Ca concentration resulted from the prolonged pH 3 treatment. The results strongly support the hypothesis that the long-term growth and nutrient allocation response of conifers to acid precipitation is dependent both on the tree species and on the nutritional status of the soil.     

Ecoprofit-Styria-prepare Thirteen pollution prevention case studies in the Styrian industry

The paper focuses upon the organization of a federal state-funded pollution prevention project in the Styrian industry. The project includes 13 companies from the textile, pulp and paper, machine building, wood working and printed circuit board manufacturing industries, covering most of the sectors and sizes in the Styrian industry. It started in January 1994 and will last for one year. It will demonstrate the possibilities of pollution prevention and the need for further research work. This project will make use of the methods and tools that were refined in the Austrian Prepare project. As a first step, a systematic balance of all the inputs and outputs of a company is made, after which the weak points and inefficiencies of material and energy use are identified and the options for improvements, both economical and ecological, are defined. Consequently, modifications in products and production lead to a situation with less waste and emissions. The preliminary lessons from these projects are presented: as a rule, the utilities (consumption of process materials and water, cleaning, energy, preparatory and finishing steps) are treated as black boxes and usually represent a considerable optimization potential. In these areas especially there is usually a lack of information and coordination as well as a need for a systematic and comprehensive approach. Leadership in the company and creative consultants are needed for starting lasting successful pollution prevention projects.     

Biologie und Biochemie des Elements Selen

The importance of selenium as an essential trace element has progressively emerged during the last years due to the analysis of selenium deficiency diseases and to the identification and characterization of a number of selenoenzymes. Selenium is incorporated in the catalytic site of the enzymes as an integral selenocysteine residue. The pathway of selenocysteine biosynthesis and incorporation has been elucidated recently for Escherichia coli. This article presents an overview on these subjects and describes the mechanisms which confer selenocysteine specificity in the framework of protein biosynthesis. In addition, some considerations concerning the phylogeny of selenocysteine incorporation are presented and a model for the evolution of the selenocysteine pathway is proposed.