Quantifying the effects of forestry practices on the recovery of upland streams and lochs from acidification

Trends in long-term chemistry data are presented for 37 acidified upland streams and lochs, located in four areas (A, B, C and D) across Scotland, to provide a comparison between recovery rates of moorland catchments and forest catchments at different stages of the management cycle. For all sites, non-marine sulfate (nm-SO(4)) showed a significant decline in annual median concentrations, the greatest decline being in streams draining felled catchments, which showed a 50% greater decline than catchments with moorland or young, aggrading forests. A similar pattern was found for chloride (Cl) concentrations in Area C, which reflected the reduced interception of sea-salt aerosols following clearfelling. However, high elevation moorland sites in Area D also revealed significant declines in Cl while trends in aggrading forest sites in this area were insignificant. Alkalinity (ALK) and pH increased more at sites where felling had taken place than at moorland or young forest sites while aggrading forest catchments appeared to be most resistant to changes in pH and ALK. Associated with these acid-base changes was a corresponding decline in labile aluminium (Al-L) concentrations. The pattern of nitrate (NO(3)) change was especially affected by the timing of felling in forested catchments. Large negative trends in NO(3) at stream sites were associated with felling during the early part of the study period. This downward trend was further enhanced as NO(3) concentrations fell below pre-felling levels as the second rotation crop became established. Few forest sites showed significant increases in NO(3) due to felling in the latter part of the study period. Most moorland loch sites showed a small but significant increase in NO(3,) probably in response to similar increases in N deposition and/or climatic impacts. Dissolved organic carbon (DOC) increased significantly at both forest and moorland sites, however, the extent of these increasing trends appeared to be positively correlated with absolute DOC concentrations. Despite the complex response of streams and lochs during the various stages of the forest cycle, especially for NO(3), both forest and moorland catchments showed generally similar and rapid responses to reductions in S deposition. Nevertheless, forested sites are still more acid and have higher concentrations of toxic forms of Al than moorland sites. Although the proposed emission reductions in Europe are likely to result in a continuing decline in S and N loadings to catchments, the continuing policy of planting second rotation forests in these acidified catchments may, in the long-term, delay or halt chemical and biological recovery. However, in the short-term, any increase in the uptake of N deposition by aggrading forests should help to counteract the acidifying effects of a small increase in the interception of S and N compounds.     

Database for a debate: a review of upland research

ENVIRONMENTAL GROUPS IN POLITICS by Philip Lowe and Jane Goyder, George Allen and Unwin, London, 1983. £15 (hardback); £6.95 (paperback).

LANDSCAPE, LAND USE AND THE LAW: AN INTRODUCTION TO THE LAW RELATING TO THE LANDSCAPE AND ITS USE by J. D. C. Harte, 450 pages, E. &; F. N. Spon Ltd., London, 1985. £25 (hardback); £14.95 (paperback).

ARCADIA FOR ALL: THE LEGACY OF A MAKESHIFT LANDSCAPE by Dennis Hardy and Colin Ward, Mansell, London, 1984. £9.95.     

An investigation into the effects of forestry plantations on the water quality of upland reservoirs in northern ireland

A study was made of a wide range of Northern Ireland lakes to determine the effect of the fertilisation of forestry plantations. Lakes with fertilised forest catchments contained very high phosphorus levels. Bioassay with Selenastrum suggested that nitrogen and phosphorus were the only elements limiting growth and the supply of iron and trace metals was sufficient for large crops in nearly all cases.     

Importance of interactions between the water column and the sediment for microbial concentrations in streams

The effect of interactions between the sediment and water column on concentrations of microbes in streams is quantified with a one-dimensional, steady state model. The effects of nine main parameters describing the flow, sediment transport, and microbial growth and decay are encapsulated in two dimensionless parameters: the Damköhler number Da, or the ratio of the time scales of advection and net growth, and the sediment interaction parameter S, or the ratio of the amount of microbes lost or gained in the sediment and the amount of microbes lost or gained in the water column. Applications of the model illustrate the importance of the sediment and identify parameters that require further study. The model predicts the field measurements of Jamieson et al. (2005b) within a factor of 2 in two of three cases, while concentrations predicted by ignoring the sediment exceed the measured values. In general, the effects of ignoring interactions with the sediment depend on Da and S. The loading predicted to meet water quality standards when the sediment is considered can be either greater than or less than the loading predicted when it is not considered. The applications of the model and an analysis of uncertainty suggest that further work on the settling velocity, attached fraction, resuspension rate, and net growth rate in the sediment would help to improve predictions of the fate and transport of microbes.     

From crisis to conservation: a critical review of the intertwined economic and political factors driving built heritage conservation policy in Hong Kong and a possible way forward

This paper provides a deeper understanding of Hong Kong’s built heritage conservation policies as they have been developed during the city’s colonial and post-colonial periods, especially the political and social factors that have prompted and influenced their development and evolution. Initial observations and thoughts are derived from the authors’ extensive conservation involvement with UNESCO and local and overseas governments as well as their experience with some of Hong Kong’s key statutory boards and government committees that deal with built heritage conservation. Through their first-hand experience, coupled with extensive research, the authors argue that conservation policies in Hong Kong have not been created with a local vision, but instead have been catalysed by external factors, in particular, those relating to economics and politics. The paper concludes with a recommendation that Hong Kong should focus on social considerations in reshaping future conservation policy, as articulated in UNESCO’s Historic Urban Landscape approach.     

Effects of soil conservation measures in a partially vegetated area after forest fires

After forest fires on the east coast of Korea in 2000, some burnt areas were left untreated. Although 80% of the area was reasonably revegetated within 3 months, about 20% of the area was partially vegetated, mainly due to a low density of sprouters and poor growing conditions (eroded soil and steep slopes). Three years after the fires, the effect of soil conservation measures, such as mulching with wood chips, seeding with native plant species and log erosion barriers (LEBs), on runoff and soil erosion were examined using runoff plots. Wood chip mulching greatly reduced runoff and sediment yields and these effects were consistent regardless of the volume of rainfall. Neither seeding nor LEBs reduced runoff and sediment yields. No positive or negative effects of mulching, seeding or LEBs on ground vegetation cover were observed. The ineffectiveness of seeding and LEBs may have been due to the steep slope, the failure of germination and establishment of seeded plants, and the small diameter of logs. Treating hill slopes with mulch should be considered where post-fire regeneration is slow and there is an absence of organic material such as litter.     

A pilot study of the efficacy of residuum lodges for managing sediment delivery to impoundment reservoirs

Residuum lodges comprise small dams constructed on feeder streams immediately before they enter a reservoir, behind which ponds form, where sediment is deposited. Despite their construction on many impoundment reservoirs (IRE) and catchwaters, little research has previously investigated their efficacy at removing sediments from feeder streams. The current pilot study has, therefore, been carried out at an IRE supplying Halifax, West Yorkshire, UK, where a residuum lodge was recently cleaned out. Sediment concentrations reaching the reservoir were reduced by up to 42% although no certain impacts were noted on the other water quality variables that were measured. Moreover, it was found that the clearance operation did not result in the release of excessive quantities of sediment into the reservoir. It was estimated that the cleared residuum lodge would take 12 years to refill. A survey of other residuum lodges in the Yorkshire region showed there to be considerable differences in their remaining capacities.     

Captured streams and springs in combined sewers: A review of the evidence,consequences and opportunities

Captured streams and springs may be flowing in combined sewers, increasing clean baseflow in pipes and wastewater treatment works (WwTWs), reducing pipe capacity and increasing treatment costs. The UK water industry is aware of this in principle, but there has been no explicit discussion of this in the published literature, nor have there been any known attempts to manage it. Instead, the current focus is on the similar intrusion of groundwater infiltration through pipe cracks and joints. We have conducted a thorough review of literature and international case studies to investigate stream and spring capture, finding several examples with convincing evidence that this occurs. We identify three modes of entry: capture by conversion, capture by interception, and direct spring capture. Methods to identify and quantify capture are limited, but the experience in Zurich suggests that it contributed 7–16% of the baseflow reaching WwTWs. There are negative impacts for the water industry in capital and operational expenditure, as well as environmental and social impacts of loss of urban streams. For a typical WwTW (Esholt, Bradford) with 16% of baseflow from captured streams and springs, we conservatively estimate annual costs of £2 million to £7 million. A detailed case study from Zurich is considered that has successfully separated captured baseflow into daylighted streams through the urban area, with multiple economic, environmental and social benefits. We conclude that there is a strong case for the UK water industry to consider captured streams and springs, quantify them, and assess the merits of managing them.     

Synthesis of dawsonite: a method to treat the etching waste streams of the aluminium anodising industry

Synthesis of dawsonite was studied as a way to deal with the etching waste streams of the aluminium anodising industry in order to reduce the emissions to the environment and also to recover useful and marketable mineral resource materials. The process of synthesis was carried out using two different waste streams arising from the etching section of an anodising process when a cascade rinsing system is employed, the spent etching bath solution (132 g/l of Al and 151 g/l of Na), and the first stage effluent from the cascade rinsing system (67 g/l of Al and 71 g/l of Na). The synthesis of dawsonite was studied as a function of NaHCO3/Al molar ratio (1-10), crystallization temperature (30-150 degrees C), and reaction time (2-48 h) using supersaturated NaHCO3 solutions. A NaHCO3/Al molar ratio of 3 was optimal to obtain dawsonite as a single phase, and a reaction time of 24 h and high crystallization temperature (150 degrees C) to improve its crystallinity. The mineral characterisation was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential thermal analysis (DTA), all of which indicated characteristics typical of the desired compound. Almost 100% of the aluminium initially present in the etching waste streams was recovered in the form of dawsonite when the appropriate conditions for its synthesis were used.     

Reproducibility of the BCR sequential extraction procedure in a long-term study of the association of heavy metals with soil components in an upland catchment in Scotland

Humic iron podzol soils from three different plots at the Glensaugh Research Station, Aberdeenshire have been sampled on an annual basis since 1990 and analysed using both total digestion and the original BCR sequential extraction procedure. Particular care was required during the oxidation of these organic soils to prevent loss of material. The residue from the sequential extraction was analysed so that the values for total concentration derived from the total digestion and from the sum of the concentrations in the fractions of the extraction procedure could be compared. The comparison was good for all three soils indicating that not only did the sequential extraction give good recovery but that this was reproducible over a period of several years. The proportion of metals extractable at each step remained relatively constant thereby demonstrating the reproducibility of the procedure and the stability of the metals in the soils over the time scale of the sampling used. Whereas the total concentrations of Cr, Cu and Ni were highest in the soil from a roadside plot, this was not the case for Cd, Pb and Zn. In the case of Pb, concentrations in soils (0-25-cm depth) well away from the road were over 100 mg/kg and well above the expected background level. The distribution of metals between each of the extracted fractions varied not only between each metal but also between each of the three soils indicating that both metal and soil influenced the measured distribution. The distribution of Pb in the roadside soil was different from those in the other two soils and over 10% was extracted in the first, acetic acid soluble, fraction.     

Significance of the soil in environmental quality improvement--a review

The broad outlines of plant and animal ecology are indicated and ecosystems are defined. The impact of agriculture and industry on these systems is indicated. The major forces bringing about instability of the soil are pointed out. Wind erosion, water erosion, nutrient and oxygen balances are described in principle. Intensification and specialization of agriculture are described in some detail. These intensive practices are compared to the older “normal” agriculture. Hence, the courses of the modern agricultural problems in environmental pollution and waste management are indicated. The magnitude of the pesticide problem is defined and the need for regulation is emphasized. Special consideration is given to chlorinated hydrocarbons and mercury compounds. The process of eutrophication is defined and is described as a natural process. Sources of artificial enrichment of the water are described as well as city and rural waste water.The remedial measures that need to be taken to maintain and/or improve the environment are discussed. Systems of handling animal wastes are described in some detail. Dry, slurry, and wet systems are described in regard to management. The control of excessive fertilizer nutrients, pesticides, and agricultural chemicals including heavy metals is outlined in some detail. Animal manure management as a part of the soil fertility system is described. Nitrogen and phosphorus management is discussed in some detail. Utilization of city waste water and sewage treatment plant sludges are indicated. Solid waste disposal on the land as a means of environmental improvement is considered from the point of view of disposing of raw sewage, sewage sludge, and solid wastes generally. Fruit and vegetable processing wastes can be treated by a process of overland flow in order to bring about adequate oxidation of these wastes. Wastes from packing plants for animal processing are much stronger wastes and require more complex treatment than fruit and vegetable processing wastes. Oil-spills as a pollutant on land are described in more or less quantitative terms. Remedial measures are given.     

Water quality in the Scottish uplands: a hydrological perspective on catchment hydrochemistry

Land above 300 m covers approximately 75% of the surface of Scotland and most of the nation's major river systems have their headwaters in this upland environment. The hydrological characteristics of the uplands exert an important influence on the hydrochemistry of both headwater streams and downstream river systems. Thus, many of the spatial and temporal patterns in the chemical quality of surface waters are mediated by hydrological processes that route precipitation through upland catchments. These hydrological pathways also have an important influence on how the hydrochemistry of upland streams is responding to increasing pressures from environmental changes at the global and regional scales. At the present time, atmospheric deposition remains an issue in many parts of the Scottish uplands, where critical loads of acidity are exceeded, particularly in areas affected by increasing N deposition. Moreover, climatic change forecasts predict increasingly wetter, warmer and more seasonal conditions, which may modify the hydrochemical regimes of many river systems, particularly those with a strong snowmelt component. On a more localised scale, land management practices, including felling of commercial forests, expansion of native woodlands, agricultural decline and moorland management all have implications for the freshwater environment. Moreover, increasing public access to upland areas for a range of recreational activities have implications for water quality. Understanding the hydrology of the uplands, through integrated field and modelling studies, particularly of the hydrological pathways that regulate chemical transfers to streamwaters, will remain an important research frontier for the foreseeable future.     

Modeling PAH mass transfer in a slurry of contaminated soil or sediment amended with organic sorbents

A three-compartment kinetic partitioning model was employed to assess contaminant mass transfer and intraparticle diffusion in systems comprising dense slurries of polluted soil or aquifer sediment with or without sorbent amendments to sequester polycyclic aromatic hydrocarbons (PAHs). The model was applied to simulate temporal changes in aqueous and particle-bound PAH concentrations comparing different pollution sources (heavy oil or tar sludge) and various sorbent amendments (polyoxymethylene (POM), coke breeze, and activated carbon). For the model evaluation, all the parameters needed were directly measured from a series of experiments, allowing full calibration and verification of model predictions without parameter fitting. The numerical model reproduced two separate laboratory-scale experiments reasonably: PAH uptake in POM beads and PAH uptake by semipermeable membrane devices. PAH mass transfer was then simulated for various scenarios, considering different sorbent doses and mass transfer rates as well as biodegradation. Such model predictions provide a quick assessment tool for identifying mass transfer limitations during washing, stabilization, or bioslurry treatments of polluted soil or sediment in mixed systems. It appears that PAHs would be readily released from materials contaminated by small oil droplets, but not tar decanter sludge. Released PAHs would be sequestered rapidly by activated carbon amendment but to a much lesser extent by coke breeze. If sorbing black carbon is present in the slurries, POM pellets would not be effective as a sequestration amendment. High first-order biodegradation rates in the free aqueous phase, e.g., in the order of 0.001 s(-1) for phenanthrene, would be required to compete effectively with adsorption and mass transfer for strong sorbents.     

Ethical practices in the landscape profession: a research note

This paper addresses the concept of ethics within the landscape professions. A definition of ethics shows how important the perceived role played by an individual is. Four elements of ethics — professional, personal, business and environmental — are identified along with their associated responsibilities, relationships and conflicts. The role of professionals in society is discussed with special reference to the environmental role of landscape professionals. The paper refers to interviews, which took place in the summer of 1994, with the Registrar and President of the Landscape Institute and relates those discussions to the ethical elements defined earlier. The paper concludes that the environmental ethic is presently left up to the individual professional and is not taken up by the professional body. Concern for the environmental ethic in the twenty first century is raised as an issue for both individuals and the Landscape Institute.     

Ethical practices in the landscape profession: a research note

This paper addresses the concept of ethics within the landscape professions. A definition of ethics shows how important the perceived role played by an individual is. Four elements of ethics — professional, personal, business and environmental — are identified along with their associated responsibilities, relationships and conflicts. The role of professionals in society is discussed with special reference to the environmental role of landscape professionals. The paper refers to interviews, which took place in the summer of 1994, with the Registrar and President of the Landscape Institute and relates those discussions to the ethical elements defined earlier. The paper concludes that the environmental ethic is presently left up to the individual professional and is not taken up by the professional body. Concern for the environmental ethic in the twenty first century is raised as an issue for both individuals and the Landscape Institute.     

Biological process of soil improvement in civil engineering:A review

The concept of using biological process in soil improvement which is known as bio-mediated soil improvement technique has shown greater potential in geotechnical engineering applications in terms of performance and environmental sustainability.This paper presents a review on the soil microorganisms responsible for this process,and factors that affect their metabolic activities and geometric compatibility with the soil particle sizes.Two mechanisms of biomineralization,i.e.biologically controlled and biologically induced mineralization,were also discussed.Environmental and other factors that may be encountered in situ during microbially induced calcite precipitation(MICP) and their influences on the process were identified and presented.Improvements in the engineering properties of soil such as strength/stiffness and permeability as evaluated in some studies were explored.Potential applications of the process in geotechnical engineering and the challenges of field application of the process were identified.     

The influence of soil characteristics on the extractability of Cd, Pb and Zn in upland and moorland soils

A study was undertaken to investigate the feasibility of using existing data sets of total soil metal concentrations and soil parameters, such as pH, to predict available metal concentrations on a regional or national basis. The attraction of such an approach is that it would provide valuable data for initiatives requiring information on the availability and mobility of metals in soils without the need for costly soil sampling and analysis. Ninety-seven topsoil and subsoil samples were collected from 6 soil series in a catenary sequence in north Wales to provide data for the development of an empirical model. These were analysed for total, 0.01 M CaCl2-extractable and porewater metal concentrations and for a range of soil properties including pH, solid and dissolved organic matter and cation exchange capacity. Regression analysis showed that, of the soil parameters measured, pH was the most important predictor variable for the estimation of CaCl2-extractable Cd, Pb and Zn. pH accounted for up to 86% of the variance in the proportion of 'total' metals which were extracted by CaCl2, a reagent that is commonly used to estimate plant uptake of elements. However, the relationships recorded between soil parameters and Kd (total metal/porewater metal) were much weaker, indicating that porewater metal concentrations can less readily be predicted from total soil metal concentrations and soil properties.