Macroalgal communities face the challenge of changing biotic interactions: review with focus on the Baltic Sea

In diverse littoral communities, biotic interactions play an important role in community regulation. This article reviews how eutrophication modifies biotic interactions in littoral macroalgal communities. Eutrophication causes blooms of opportunistic algae, increases epibiotism, and affects regulation by grazers. Opportunistic algae and epibionts harm colonization and growth of perennial algae. Grazing regulates the density and species composition of macroalgal communities, especially at the early stage of algal colonization. Eutrophication supports higher grazer densities by increasing the availability and quality of algae to grazers. This may, on the one hand, enhance the capability of grazers to regulate and counteract the increase of harmful, bloom-forming macroalgae; on the other hand, it may increase grazing pressure on perennial species, with a poor tolerance of grazing. In highly eutrophic conditions, bloom-forming algae may also escape grazing control and accumulate. Increasing epibiotism and grazing threaten in particular the persistence of habitat-forming perennials such as the bladderwrack. An interesting property of biotic interactions is that they do not remain fixed but are able to evolve, as the traits of the interacting species adapt to each other and to abiotic conditions. The potential of plants and grazers to adapt is crucial to their chances to survive in changing environment.     

Permafrost and changing climate: the Russian perspective

The permafrost regions occupy about 25% of the Northern Hemisphere's terrestrial surface, and more than 60% of that of Russia. Warming, thawing, and degradation of permafrost have been observed in many locations in recent decades and are likely to accelerate in the future as a result of climatic change. Changes of permafrost have important implications for natural systems, humans, and the economy of the northern lands. Results from mathematical modeling indicate that by the mid-21st century, near-surface permafrost in the Northern Hemisphere may shrink by 15%-30%, leading to complete thawing of the frozen ground in the upper few meters, while elsewhere the depth of seasonal thawing may increase on average by 15%-25%, and by 50% or more in the northernmost locations. Such changes may shift the balance between the uptake and release of carbon in tundra and facilitate emission of greenhouse gases from the carbon-rich Arctic wetlands. Serious public concerns are associated with the effects that thawing permafrost may have on the infrastructure constructed on it. Climate-induced changes of permafrost properties are potentially detrimental to almost all structures in northern lands, and may render many of them unusable. Degradation of permafrost and ground settlement due to thermokarst may lead to dramatic distortions of terrain and to changes in hydrology and vegetation, and may lead ultimately to transformation of existing landforms. Recent studies indicate that nonclimatic factors, such as changes in vegetation and hydrology, may largely govern the response of permafrost to global warming. More studies are needed to better understand and quantify the effects of multiple factors in the changing northern environment.     

The changing sediment load of the Mekong River

The sediment loads of many of the world's major rivers have changed significantly in recent years due to land-use change, reservoir construction, and other human impacts on their drainage basins. For many rivers, the loads have decreased, whereas for others, they have increased. Such changes can have important implications for both the natural functioning of the system as well as for human exploitation of the river system. This paper considers the evidence for recent changes in the sediment load of the Mekong River. The available data have a number of limitations in terms of both sampling frequency and the period of coverage, but they have been processed to provide a basis for considering the changes in the sediment load of the river over the period extending from the early 1960s to 2002. Although there is evidence of increasing loads at some measuring stations, the overall trends show little evidence of major changes, and the system provides evidence of buffering through storage. As of 2002, the construction of major dams on the headwaters in China appears to have had little impact on the sediment load, although as further larger dams are commissioned, the sediment load of the Mekong can be expected to decrease.     

Epidemiological Aspects of Air Pollution

An urban air pollution incident, like a natural or man-made catastrophe, presents a crisis situation which can only be relieved if adequate contingency plans have been prepared in advance and an effective control organization is in a state of operational readiness to meet the threatened emergency. Although many air pollution incident control plans have been proposed in the past, most have remained in the conceptual or theoretical stages of preparation, because the relative infrequency of serious urban air pollution crises and the disruptive nature of major emission control operations tend to limit the opportunities available for field testing of these plans. In this respect, air pollution incident control planning is analogous to strategic planning for a military operation, where the only completely legitimate test of a strategy is applied on the battlefield. In order to accomplish the transition from conceptual planning to a practical, operational field strategy for air pollution incident control, a program of incident control tests has been initiated in Chicago. These field tests, which use the city as a laboratory for the development of control strategies, are analogous to a series of military war games in which communication systems, command and control organizational structures, personnel roles, surveillance and monitoring equipment, control resources and pollution source controllability are tested under conditions which approximate as closely as possible the situation which prevails during an actual air pollution incident. This paper discusses the evolution of an incident control strategy from an initial, fixed response emission control exercise, through a meteorologically initiated control test to a fairly realistic war game series which is still developing.     

Evidence for changing the critical level for ammonia

The current critical level for ammonia (CLE_NH3) in Europe is set at 8 μg NH₃ m⁻³ as an annual average concentration. Recent evidence has shown specific effects of ammonia (NH₃) on plant community composition (a true ecological effect) at much smaller concentrations. The methods used in setting a CLE_NH3 are reviewed, and the available evidence collated, in proposing a new CLE_NH3 for different types of vegetation. For lichens and bryophytes, we propose a new CLE_NH3 of 1 μg NH₃ m⁻³ as a long-term (several year) average concentration; for higher plants, there is less evidence, but we propose a CLE_NH3 of 3 ± 1 μg NH₃ m⁻³ for herbaceous species. There is insufficient evidence to provide a separate CLE_NH3 for forest trees, but the value of 3 ± 1 μg NH₃ m⁻³ is likely to exceed the empirical critical load for N deposition for most forest ecosystems.     

Response and adaptability of mangrove habitats from the Indian subcontinent to changing climate

Mangroves, a predominant coastal habitat in the tropics, are constantly threatened by various anthropogenic pressures that are deteriorating the mangroves to a great extent. Global emissions of greenhouse gases are likely to raise the world temperature and the sea level at the rate of 0.3 degrees C and 6 mm 10 y(-1) by the year 2100. Mangrove habitats would be more vulnerable to climatic changes and resultant sea level rise (SLR) because of their unique location at the interface of the sea. By altering ecobiological processes, the intertidal and supratidal zones may extend further inland, resulting in changes in the existing ecological setup. The limitation of the landward margin would cause vertical rise, resulting in water-logging and ultimately killing the mangroves and dependent biota. The present document describes mangrove habitats and related issues from the Indian subcontinent in the context of climate variations and SLR, and recommends integrated long-term monitoring.     

Investigating the tipping point of crop productivity induced by changing climatic variables

Environmental Science and Pollution Research - South Asia is comprised of several countries, including Bangladesh, Pakistan, India, and Sri Lanka, all ranked highly at risk of climatic variability....     

An Epidemiological Appraisal of the Effects of Ambient Air on Health: Particulates and Oxides of Sulfur

This review has attempted to evaluate the present state of our knowledge of the effects on health in man of environmental exposure to oxides of sulfur, sulfates, and particulate matter. There has been a great deal of activity in this field over the last 15 years, and therefore any collation of this material will represent the selected biases of the reviewer. The conclusions reached can be summarized as follows: (1) These pollutants, as they have been measured in epidemiological investigations, can only be considered as indirect indices of general air pollution and in many cases cannot be separated from each other. Therefore, we cannot incriminate a specific source of any one pollutant as the producer of the most harmful substance to reach the ambient air. Conversely, we cannot excuse any specific source of one pollutant because that specific pollutant has not been found to cause disease at a given concentration. The measurements in ambient air are the net results from all sources of pollution in combination with factors influenced by weather and meteorological considerations. (2) Direct effects from acute, high ambient air pollution disasters have been adequately demonstrated. Significant excess mortality has occurred in association with particular air pollution episodes. All of these episodes have occurred during cold weather, and the effects of temperature must also be considered along with elevated levels of smoke and sulfur oxides. (3) Specific working groups exposed to unusually high levels of these pollutants do not demonstrate dramatic effects. This is presumably related to the fact that susceptible people are self-selected out of these environments. (4) Associations between the prevalence of chronic respiratory disease in the general population and specific levels of these air pollutants have been demonstrated. The major thrusts of epidemiological investigations have been to study the effects of chronic exposure to ambient levels of smoke and sulfur dioxide. The studies to date have collected and analyzed point-prevalence data and information obtained from retrospective investigations. Although epidemiological investigations cannot prove a cause-and-effect relationship, the consistency of the results is such that one must conclude that a causal association is likely. In this reviewer’s opinion we have reached the stage at which we no longer need to demonstrate the effect of past exposure to these pollutants. What is needed now is to demonstrate the effects of current and continued exposure. This will require a better understanding of the natural history and pathophysiology of the diseases thought to be associated with chronic exposure to smoke and sulfur dioxide. Because of the nature of chronic respiratory disease, groups of subjects for whom exposure is known, must be followed over extended periods of time. The logical extension of these observations will be the follow-up of large populations for whom exposure has been reduced. Only by studies of this kind may we be able to prove the cause-and-effect relationship which most likely exists.     

Forest ecosystems and the changing patterns of nitrogen input and acid deposition today and in the future based on a scenario

A global assessment of the impact of the anthropogenic perturbation of the nitrogen and sulfur cycles on forest ecosystems is carried out for both the present-day [1980-1990] and for a projection into the future [2040-2050] under a scenario of economic development which represents a medium path of development according to expert guess [IPCC IS92a]. Results show that forest soils will receive considerably increasing loads of nitrogen and acid deposition and that deposition patterns are likely to change. The regions which are most prone to depletion of soils buffering capacity and supercritical nitrogen deposition are identified in the subtropical and tropical regions of South America and Southeast Asia apart from the well known 'hotspots' North-Eastern America and Central Europe. The forest areas likely to meet these two risks are still a minor fraction of the global forest ecosystems, though. But the bias between eutrophication and acidification will become greater and an enhanced growth triggered by the fertilizing effects of increasing nitrogen input cannot be balanced by the forest soils nutrient pools. Results show increasing loads into forest ecosystems which are likely to account for 46% higher acid loads and 36% higher nitrogen loads in relation to the 1980-1990 situation. Global background deposition of up to 5 kg N ha-1 a-1 will be exceeded at more than 25% of global forest ecosystems and at more than 50% of forest ecosystems on acid sensitive soils. More than 33% of forest ecosystems on acid sensitive soils will receive acid loads which exceeds their buffering capacity. About 25% of forest areas with exceeded acid loads will receive critical nitrogen loads.     

Effects of a reactive barrier and aquifer geology on metal distribution and mobility in a mine drainage impacted aquifer

The Nickel Rim aquifer has been impacted for five decades by a metal-rich plume generated from the Nickel Rim mine tailings impoundment. Metals released by the oxidation of pyrrhotite in the unsaturated zone of the tailings migrate into the downgradient aquifer, affecting both the groundwater and the aquifer solids. A reactive barrier has been installed in the aquifer to remove sulfate and metals from the groundwater. The effect of the reactive barrier on metal concentrations in the aquifer solids has not previously been studied. In this study, a series of selective extraction procedures was applied to cores of aquifer sediment, to ascertain the distribution of metals among various solid phases present in the aquifer. Extraction results were combined with groundwater chemistry, geochemical modelling and solid-phase microanalyses, to assess the potential mobility of metals under changing geochemical conditions. Reactions within the reactive barrier caused an increase in the solid-phase carbonate content downgradient from the barrier. The concentrations of poorly crystalline, oxidized phases of Mn and Fe, as well as concentrations of Cr(III) associated with oxidized Fe, and poorly crystalline Zn, are lower downgradient from the barrier, whereas total solid-phase metal concentrations remain constant. Iron and Mn accumulate as oxidized, easily extractable forms in a peat layer overlying the aquifer. Although these oxides may buffer reducing plumes, they also have the potential to release metals to the groundwater, should a reduced condition be imposed on the aquifer by remedial actions.     

春蚕期桑叶氟化物含量变化规律分析与研究

春蚕桑叶氟化物中毒引起政府部门的高度重视。通过对历年来桑叶含氟量监测数据统计分析,找出春蚕期桑叶含氟量日均值变化规律,并对规律成因进行探讨研究,为春蚕防氟工作提供科学依据。     

The environmental impact of changing consumption patterns: a survey

How does environmental impact change when national income increases? So far, this question has been mainly discussed from the point of view of production, but in recent years several studies have dealt with the question of decoupling from the point of view of consumption. The optimistic subscribers to decoupling argue that, with increasing income, the composition of consumption changes in the direction of more environment-friendly goods and services. This paper discusses this hypothesis critically on the basis of several studies dealing with historical experience. First, it is argued that an overall assessment of the environmental impact is most appropriately based on an input approach. Then data on input intensities for different categories of consumption goods are combined with data on changes in consumption patterns, and it is concluded that the historical changes in the composition of consumption seem to have done little to counterbalance the environmental effects of growth.     

Assessing the effects of changing demographic and consumption patterns on sea tenure regimes in the Roviana Lagoon,Solomon Islands

This paper investigates how sea tenure institutions in the Roviana Lagoon, Solomon Islands, mediate among population, consumption, and the environment. The focus is on explaining how growth in population and consumption alter sea tenure regimes, and the factors that shape either their institutional robustness or vulnerability. The paper also addresses the regional differences among sea tenure institutional arrangements, the processes that are producing them, and the social and environmental outcomes of these institutions as they engage external forces and internal changes. A major question is how existing forms of sea tenure respond comparatively when faced with parallel demographic and economic transformations? Two villages representing different sea tenure arrangements within the Roviana Lagoon are compared. Results show that inhabitants in these villages perceive their systems of sea tenure governance similarly; yet their managerial responses to changes brought about by growth in population and consumption differ, and the responses produce contrasting environmental effects.     

土地利用变更的土壤及地下水污染调查方法及实例

以南京大厂区某地块的土壤及地下水污染调查为实例,提出了资料收集、源项分析、监测因子筛选、监测布点．场地地质水文勘探和土壤及地下水采样分析的土壤及地下水污染调查方法,探讨了评价标准和确定土壤及地下水污染范围的方法。     

Importance of water level management for peatland outflow water quality in the face of climate change and drought

Environmental Science and Pollution Research - The impact of different climate scenarios, drought, and water level management on the outflow water quality of peatlands has been investigated. A...     

Multi-element composition of historical lichen collections and bark samples,indicators of changing atmospheric conditions

Thirty six element signatures were compared in historical Parmelia sulcata samples from the Natural History Museum herbarium collected over the period 1797–1967 with those recorded in the same species and tree bark sampled in 2000 from Burnham Beeches, lying 40 km west of London. Nineteen elements reached highest concentrations in herbarium samples, consistent with a pollution legacy and dust contamination in the herbarium. Healthy Parmelia sampled east and down-wind of London at a farm during peak SO₂ emissions in 1967 contained highest V, Ni, Zn, Cd, Se, Ge contents, supporting derivation from fuel combustion; the same sample was previously determined as having a low δ34S and high S and N contents. Lowest V, Co, Ni, Cu, Zn, Sn, Ba, Pb, Mo, Sb, Li, B, Cs, U, Th, Ga contents were recorded in a sample with a high δ34S and low S content collected in 1887 from a remote region from Ross-shire, Scotland. Se and Cd enrichment, never-the-less suggest a transboundary pollution influence. Lichen Pb concentrations from Burnham Beeches were amongst the lowest recorded in spite of lichens being collected close to roads. Herbarium samples help interpret changes in element deposition where few data exist, in spite of dust contamination.     

The changing state of contamination in the Lagoon of Venice. Part 1: organic pollutants

The Lagoon of Venice is a transitional environment suffering from industrial, urban and agricultural impact. Recently the mechanical clam fishing, preventing a regular deposition of sediments has made sampling of cores suitable for radiodating very problematic. Therefore, in this study, in order to assess temporal and spatial trends of contamination, the same sampling scheme was repeated three times over a 12-year period. The concentrations of PCBs, PAHs and organochlorine pesticides were measured in the uppermost 5 cm of sediments collected in 25 sites in the central portion of the lagoon during three campaigns conducted in 1987, 1993 and 1998. Analytical results, validated statistically, indicated that, while PCB and pesticide concentrations tend to decrease during the considered period of time, PAH do not, showing that the input rate of these compounds to the lagoon environment is still important. A spatial trend of pollution was also found in the lagoon for PCBs and pesticides, which decrease from the sources, namely the industrial zone and the mouths of rivers, to areas closer to the sea: a reduction up to 80% and 90%, respectively, was monitored. PAH contamination, originating chiefly from incomplete combustion of fossil fuels, as inferred from ratios of congeners, was mainly located around the historical center of Venice, where most of the boat traffic is concentrated and has an increasing trend.