An efficient way for assessing the nutrient status of an ecosystem is the establishment of nutrient input-output mass balance budgets at the catchment scale. For example, outputs (i.e. losses in streamwater, through havesting etc.) greater than inputs (i.e. weathering, dry and wet deposition, fertiliser) indicate that a depletion of the given element is taking place. In forest ecosystems, element input via throughfall is an important pathway in nutrient cycling. Precipitation interacts with the stand canopy, resulting in increased/decreased solute inputs to the forest floor. For example, acid deposition (H, N) may be substantially increased through the filtering action of the tree canopy. Indeed, canopy throughfall chemical composition includes wet deposition (rainfall), dry deposition intercepted by the canopy and elements leached from the foliar tissue (canopy leaching). Moreover, interactions between canopy and atmosphere or precipitation depend on several factors such as: season, tree species and physiology, stand structure and health. However, canopy leaching results from an internal nutrient cycling process. Ignoring this component in throughfall measurements thus leads to an overestimation of the inputs to the ecosystem. In this paper, main results of studies performed in the Belgian Ardennes at the watershed (80 ha) and plot scale are summarised. The aim of this research was to quantify long-term nutrient budgets in a forested watershed, within a context of sustainable management. In this area, soils are naturally acidic and poor in magnesium, so that forest dieback symptoms reported from 1983 onwards were related to increased pollution exacerbating magnesium deficiency. There is concern that acid (S and N) deposition, together with sylvicultural management (harvesting, spruce monocultures etc.) could deplete the available cation pool and that soils would not be able to support intensive sylviculture on the long term. We measured concentrations and fluxes of major ions in bulk deposition, throughfall and stream water over 13 years. Throughfall deposition under coniferous (Picea abies (L.) Karst.) and several deciduous tree species was also compared. A canopy budget method was used for distinguishing between external (dry deposition) and internal (canopy leaching) sources of ions in the throughfall flux. The contribution of canopy leaching in throughfall measurements and consequences for mass balance calculations will be discussed. Furthermore, nutrient fluxes through the ecosystem will be examined with regard to the long term nutrient status of the system.

Human transport by land, sea and air has increased exponentially through time in intensity, paralleling rises in population, prosperity and rates of technological change. Transport has considerable ecological effects, many of them detrimental to environmental sustainability. This volume brings together international experts from a variety of disciplines to review the ecological effects and their causes in terms of road, rail, ship and aircraft transport. The contributors have different attitudes and agendas. Some are ecologists, some planners, others social scientists. Focus ranges from identification of threats and amelioration of damaging effects through to future design of transport systems to minimize environmental degradation. Some chapters consider restricted areas of the globe; others the globe itself. Views encompass deep pessimism and cautious optimism. Uniquely, the volume considers transport effects in all environments. This is the first book that attempts to discuss the relationship between human transport and all ecosystems. It appeals not only to the specialist environmentalist by picking out novel topics, but also to anyone involved in transport issues as it tackles the issues from an historical perspective, encompassing the past, present and future of the effects of human transport.

An in situ erosion flume was used to measure the stability of sediment deposits in Hamilton Harbour, Ontario, Canada. The flume consists of a rectangular duct with an opening at the bottom. A submerged pump attached to the downstream end of the flume circulates the ambient water through the flume, thereby generating turbulent shear flows inside the flume. When the flume rests on a sediment deposit, the exposed part of the sediment deposit is subjected to the flow shear stress. By applying a continually increasing flow shear stress on the sediment deposit and by measuring the amount of sediment erosion, it is possible to assess the erosional stability of the sediment deposits. An under water video camera was mounted on the flume to get visual images of the sediment erosion process. The flume was used at two sites in the Harbour. The erosional resistances measured by the flume for the two sites were different. Measurement of dry density of the sediment deposits using an ultrasonic device was carried out to explain the differences in the stability of sediment deposits from the two sites.

Cootes Paradise is a coastal wetland, adjacent to Hamilton Harbour at the western tip of Lake Ontario. The marsh has been considerably degraded due to the excessive sediment and nutrient input from sewage treatment plants (STPs), marsh tributaries and Combined Sewer Overflows (CSOs). Although there has been reduction in nutrient loadings from external sources, high nutrient levels, and a prolific algal growth remain a problem in Cootes Paradise. To assess the importance of external versus internal nutrient loadings to the marsh, nutrient fluxes from sediments were estimated using porewater profiles at three locations from 2001 and five additional sites from 2002. The fluxes varied between 0.27 and 5.25 mg P m-² day-¹, with sites receiving outfalls of STP and CSO having highest fluxes (~5 mg P m-² day-¹). Mean phosphorus release rate of 2.02 mg P m-² day-¹ was calculated from the spatial distribution of the non-apatite inorganic phosphorus (NAI-P) in sediments, employing a relationship between the NAI-P and P fluxes. The results confirm that sediment P geochemistry is important in regulating the P pool in porewater which, consequently, governs the P fluxes from sediments.

Cohesive sediments besides their typical heterogeneity are characterised by structural discontinuity. Particularly, organic consolidated muds are a good example of sediments that consist of vast aggregates, pore water and gaseous products. The texture of a cohesive sediment bed is a result of a number of mutually affecting factors, such as deposition history, mineral and organic composition, kind of biota and oxygen uptake. The presented work attempts to quantify the effect of sediment physical properties and sediments structure on the sediment erosion potential, considering incipient motion and erosion rate. This quantification is made on the basis of comparative testing of both unremoulded and remoulded samples of a river mud. Due attention is paid to sediment handling to preserve the delicate structure of the sediment for the laboratory experiments. Mud with two degrees of consolidation has been examined in a tilting flume under different flow situations. The test results show a typical increase of erosion strength with dry matter concentration of the mud. It has also been found that the structural properties increase the erosion strength for the less consolidated mud. An opposite effect has been recorded for a more consolidated deposit. As a consequence, due to the sediment structure, the original beds differ much less in erosion resistance in relation to the dry mass concentration than their disturbed analogues. Finally, the erosion resistance of the examined mud is compared with data from the literature.

Lignite mining and processing has caused a pronounced impact both directly and indirectly on soils and ecosystems across large areas of the former GDR. We studied soils of pine forest ecosystems at sites affected by severe alkaline dust and sulphur deposition, stemming from lignite fired power plant emission, and at dumped sites from lignite mining. In this paper we summarize our main results and evaluate the long-term impact of lignite mining and combustion on the environment. The pine ecosystems on naturally developed soils show a clear effect of deposition history along a former deposition gradient with distinct changes in chemical properties of organic surface layers and mineral soil as well as in element turnover and cycling rates. Afforested sites on mining dumps are directly affected by the composition of the dumped substrates. Over a large area (800 km²) these substrates are dominated by Tertiary sediments with varying amounts of lignitic particles and pyrite that result in phytotoxic site conditions (pH < 3, high salt and metal contents). High amelioration doses of liming material (up to 200 t ha-¹) were applied for restoration purposes. We studied the development of these sites over a period of 60 years using a false-time series approach. Beside the extreme soil conditions, element budgets of these sites are characterized by very high element release rates over decades caused by pyrite oxidation and primary mineral weathering.

The adsorption and degradation of chlorobenzene on partially modified organoclays and by the autochthonous microorganism Rhodococcus B528 were studied by means of the batch technique. Organoclays were prepared from Na-montmorillonite (MM) by using dodecyltrimethylammonium (C₁₂) and dioctadecyldimethylammonium (2C₁₈) bromides. The degree of modification was 35 (2C₁₈-35-MM) and 89% (C₁₂-89-MM) of the cation exchange capacity of MM. The adsorption experiments were carried out using headspace GC. The intercalation of chlorobenzene into the interlayers of organo-MM was detected by X-ray diffraction. The adsorption isotherms found were of the S1 type indicating a cooperative effect. Chlorobenzene showed a higher affinity for 2C₁₈-35-MM than C₁₂-89-MM, which could not only be explained by the organic carbon content. The comparison with 2,4-dichlorophenol adsorption has implied that for the studied systems the different adsorption mechanisms are primarily governed by the different molecular properties and not by the type of absorbent. The presence of 2C₁₈-35-MM caused no negative effect on the investigated microorganisms and complete biodegradation of chlorobenzene was achieved without desorption limitation for growth, demonstrating the applicability of partially modified organoclays for bioremediation.

Atmospherically deposited lead in the upper layer of the heavily eroded peatlands of the Peak District, southern Pennines, UK, reaches concentrations in excess of 1,000 mg kg-¹. Erosion of the upper peat layer in this region is releasing lead, associated with eroded peat particles, into the fluvial system. Understanding the process mechanisms that control dissolved lead concentrations in contaminated peatland streams is vital for understanding lead cycling and transport in peatland streams. Many headwater streams of the southern Pennines recharge drinking water reservoirs. Measurements in the Upper North Grain (UNG) study catchment show that mean sediment-associated and dissolved lead concentrations are 102 ± 39.4 mg kg-¹ and 5.73 ± 2.16 μg l-¹, respectively. Experimental evidence demonstrates that lead can desorb from suspended sediments, composed of contaminated peat, into stream waters. In-stream processing could therefore account for the elevated dissolved lead concentrations in the fluvial system of UNG.