Methods for constructing and balancing ecosystem flux charts: new techniques and software

We describe a general computer program which employs novel techniques to analyze carbon (energy) and nutrient flows in complex food webs. The program uses estimates of metabolic/physiological parameters and ecosystem fluxes to simultaneously calculate the most likely balanced flux charts for carbon and a nutrient. We give an example of how the model can explore the theoretical issues involved with nutrient limitation and recycling.     

Utility of dynamics as indicators of stress in population models

The relationships between the dynamics of environmentally and chemically stressed populations and indicators of the effects of the stressor are explored in a model framework. The physiologically structured population, represented by a system of McKendrick–von Foerster hyperbolic partial differential equations, includes the dynamics of numerous individuals distinguished by ecotype. Chemical uptake of nonpolar narcotics is modeled by first order kinetics. Classical methodologies, frequency analysis and phase space reconstruction, are explored in a search for indicators of magnitude of stress. When these techniques proved generally unsuccessful for the objective of indicator selection in our model setting, summary statistics, as related to bifurcation diagrams, were constructed and appear more useful as indicators. It is concluded that physiological structures generally lead to more feasible measurable indicators of magnitude of stress than do specifics of population dynamics.     

环境中萘和甲基萘的气相色谱测定

针对发生的甲基萘油车泄漏事故进行了水样和空气样品中萘和甲基萘的测定，水样中直接进样，对空气样品则以甲醇为吸收液吸收，富集，氢火焰毛细管色谱法测定。     

Development of a practical forest ecosystem classification from existing biophysical studies: An approach used in northwestern Quebec

While forest ecosystem classification work in Quebec has traditionally concentrated on inventory and mapping, more effort is now being placed on developing field guides similar to those produced in other Canadian provinces. As part of a project to produce a practical forest ecosystem field guide for the Amos Lowlands Ecological Region in northwestern Quebec, existing sub-regional ecological studies were exploited in order to develop a regional classification of forest ecosystems, or forest stations. Review of four fundamental studies provided a list of 107 ecological phases, each representing a particular combination of forest composition, surface deposit type and moisture regime. A series of silvicultural and environmental interpretations were developed and values for each were attributed to the ecological phases. Cluster analysis was then performed to classify phases into 29 broader units. A large, regional biophysical database which became available later in the project provided a means of validating and effectively modifying the classification. The justifications for using the original approach are discussed.     

Fractionation of heavy metals and phosphorus in suspended sediments of the Yamuna river,India

The Yamuna river is the largest tributary of the Ganges river system. It originates in the Himalayas and flows through a varied geological terrain encompassing a large basin area. Metals Fe, Mn, Pb, Zn, Cu in different chemical fractions of suspended sediments such as exchangeable, carbonates, Fe–Mn oxides, organics and residual fractions were studied. Phosphorus associated with different chemical forms are discussed. The metals are mostly associated with residual fractions in the sediments followed by organics, Fe–Mn oxides, exhangeable and carbonates. Intensive use of chemical fertilizers and pesticides in agriculture in the basin affects the high inorganic phosphorus content in sediments.     

Environmental and sustainability indicators and the concept of situational indicators. A systems approach

Through a systems approach indicators are shown to have the nature of variables, adopting different values or states, while other associated terms allude to special meanings assigned to specific values of the indicators. Practical implications are discussed. The concept of situational indicators of sustainability is introduced, representing a non-numerical function of both “pressures” or “driving forces” and “state” variables. A cost-effective multi-tiered approach to situational indicators is proposed. The concept of situational indicators is shown to be a particular case of indicators of systems behavior. A general systems formulation of the problem of sustainability highlights the importance of indicators of systems behavior and the central role of models in their definition.     

Fuel characteristics and emissions from biomass burning and land-use change in Nigeria

Nigeria is one of the 13 low-latitude countries that have significant biomass burning activities. Biomass burning occurs in moist savanna, dry forests, and forest plantations. Fires in the forest zone are associated with slash-and-burn agriculture; the areal extent of burning is estimated to be 80% of the natural savanna. In forest plantations, close to 100% of litter is burned. Current estimates of emissions from land-use change are based on a 1976 national study and extrapolations from it. The following non-carbon dioxide (CO₂) trace gas emissions were calculated from savanna burning: methane (CH₄), 145 gigagrams (Gg); carbon monoxide (CO), 3831 Gg; nitrous oxide (N₂O), 2 Gg; and nitrogen oxides (NO_x), 49 Gg. Deforestation rates in forests and woodlands are 300 × 10³ ha (kilohectare, or kha) and 200 × kha per year, respectively. Trace gas emissions from deforestation were estimated to be 300 Gg CH₄, 2.4 Gg N₂O, and 24 Gg NO_x. CO₂ emissions from burning, decay of biomass, and long-term emissions from soil totaled 125 561 Gg. These estimates should be viewed as preliminary, because greenhouse gas emission inventories from burning, deforestation, and land-use change require two components: fuel load and emission factors. Fuel load is dependent on the areal extent of various land uses, and the biomass stocking and some of these data in Nigeria are highly uncertain.     

Risk assessment of water pollutants

The sources of toxic xenobiotics and different factors such as ecological diversity, differences in comparative anatomy, physiology and biochemistry, food chain variation, interrelationship within species and life span, etc., are considered during risk assessment of pollutants, and their impact on aquatic ecotoxicology is identified. A fugacity and multimedia compartment model is suggested, based on toxicodynamic (toxicity of the chemical) and toxicokinetic (metabolism of the chemical) considerations to predict and screen the behaviour of pollutants quantitatively in the aquatic environment. The significance of the risk analysis approach in anticipatory actions and regulation of pollution levels is discussed.     

The efficacy of a limestone doser to mitigate stream acidification in a Maryland coastal plain stream: Implications for migratory fish species

The objective of this two-year study was to determine the efficacy of an automated limestone slurry doser to neutralize acidic pulses and improve water quality conditions for enhancing survival of early life stages of migratory fish species in a Maryland coastal plain stream. Implications for survival of early life stages of migratory fish species such as yellow perch (Perca flavescens), white perch (Morone americana), blueback herring (Alosa aestivalis) and alewife (Alosa pseudoharengus) are discussed based on the improved chemical conditions in the dosed area of the stream. Despite problems with overdosing in 1991 and failure of the stage transducer to work properly in 1992, the doser was generally effective in neutralizing acidic pulses (pH depressions) in the stream during three major rain events in both years. Chemical conditions (pH and inorganic monomeric aluminum) reported in the non-dosed area during major rainfall events were potentially stressful to both alewife and blueback herring although neither species was reported spawning in the stream during either year. Mitigating the potential impact of acidic conditions on early life stages of important migratory fish species was not sufficient to ensure spawning. It is therefore recommended that habitat improvement measures and well designed fish stocking programs be implemented concurrently with doser operations if the goal is to create optimum spawning conditions for migratory species.     

The need for long-term stream monitoring programs in forest ecosystems of the Pacific Northwest

Concepts, planning and design procedures are examined that are needed in the development of long-term stream monitoring programs in forested regions. A long-term stream monitoring program is viewed as the key component for bringing together management organizations, researchers and decision-makers to improve the management of natural resources. The keystones of such ecosystem monitoring are long-term data records that provide the basis for analysis of environmental assessment objectives, predictions and analysis of outcomes which in-turn can be used to modify and improve future projects. Management organizations that initiate long-term monitoring programs are urged to use monitoring actions and information to facilitate decision-making processes that pertain to conserving and allocating resources for future beneficial uses. Recommendations are provided for careful planning and definition of interactive activities of monitoring programs and that should provide information feedbacks that can be used to evaluate issues pertaining to beneficial uses of resources. Procedural requirements and literature sources are suggested for developing long-term stream monitoring programs. They include reviews of background and historical information to provide precise definitions of long-term objectives, planning considerations and monitoring methods. Examples are given of specific procedures that need to be identified during the planning process. They include the application of management standards to variable conditions encountered within natural ecosystems and the detection of the timing of recovery phases of stream ecosystem development following a disturbance. These procedures are viewed as being essential for improving applications of management standards and perceived thresholds to stream and watershed ecosystems monitoring programs.