A review of liming as a technique for protecting salmonid fish populations in acidified surface waters

Liming is a common technique that has been used in many countries to raise the alkalinity of acidified surface waters and alleviate some of the damaging effects of acidification on salmonid fish populations. The most common liming substance used is calcite, a calcium carbonate compound that is relatively inexpensive, available in different particle sizes and dissolves relatively quickly. It can be applied directly to streams or lakes or it can be applied to catchment soils. When applied to catchment soils its effect can be long-lasting but it can cause significant damage to those catchment plant and animal communities that are naturally adapted to acidic conditions. When applied directly to surface waters its effect can be immediate but applications need to be continuous or frequently repeated to counter downstream dilution and loss. For streams the most effective method is to use an automatic doser controlled by pHmeasuring sensors upstream and downstream of the doser to enable the exact quantity of lime needed to be added to the water body. Although effective this is an expensive method and one that needs to be maintained continuously for several years until the critical load exceedance has been eliminated. An alternative or complementary method is partial catchment liming by targeting water sources and selected wetlands to minimise damage to catchment vegetation. Liming can be very effective in restoring and protecting salmonid fish populations, but if over-applied it can lead to unwanted increases in alkalinity and productivity that may produce symptoms of eutrophication and unwanted changes in the composition of plant and algal communities downstream

Land-use experiments in the Loch Laidon Catchment: 2007 data report on Stream Water Quality to the Rannoch Trust

In 1992 the Rannoch Trust established the Loch Laidon catchment land-use experiment, which is investigating the effects of summer cattle grazing on the terrestrial and aquatic upland environment. Situated in Perthshire, Scotland, the study area falls within a number of designations, including the Rannoch Moor Special Area of Conservation and Site of Special Scientific Interest, the Rannoch Lochs Special Protection Area and the Tayside Local Biodiversity Action Plan

Land-use experiments in the Loch Laidon Catchment. Eighth report on Stream Water Quality to the Rannoch Trust

This report presents the results from the Stream Water Quality component of the Loch Laidon catchment land-use experiment which began in 1992. The experiment was set up to examine the effects of cattle grazing on the aquatic and terrestrial habitats and biota of a moorland area of upland Scotland

Recent heavy metal contamination of the Thurne Broads

The banning of tributyltin (TBT) from boat antifouling paints in the late 1980s led to its replacement by alternative biocide additives (Voulvoulis et al., 2000; Marcheselli et al., 2010), including Cu (Dahl & Blanck, 1996) and Zn as active ingredients. It has been reported that Cu and Zn compounds associated with these biocides have caused substantial contamination of harbour and marina sediments (Eklund et al., 2010; Parks et al., 2010), with negative toxic consequences for aquatic organisms (Ytreberg et al., 2010). Indeed, it is evident that Cu and Zn compounds present in paint fragments are readily leached into the water column allowing entry into aquatic food webs (Jessop & Turner, 2011). Nevertheless, relatively little is known regarding antifoulant-derived metals contamination in freshwater lakes. The Norfolk and Suffolk Broads (Eastern England, UK) have been contaminated by antifoulant-derived heavy metals, particularly Cu and Zn which have increased since the banning of TBT (post-1987) in parts of the boated system (Boyle et al., in prep.). Further, recent studies suggest that current levels of sediment contamination by Cu may have negative ecological effects for aquatic ecosystems including inhibition of aquatic macrophyte germination and performance (Boyle et al., submitted; S. Lambert, unpublished data). In Hickling Broad (Thurne Broads system), post-TBT increases in Cu and Zn are also evident, with an interesting peak in Cu for the late 1990s in core HICK1 (Figure 1). This coincides with the large-scale loss of aquatic macrophytes (especially Characeae) from the lake in 1999 (Barker et al., 2008). HICK1 was collected in 2003. In the proposed study we sought to gain a fuller understanding of recent metal contamination in Hickling Broad up to the present day, whilst looking to verify and better contextualise the late 1990s Cu peak. Further, we aimed to determine whether the peak in Cu for Hickling Broad was also recorded at Horsey Mere which is used as a control site in this study i.e. is it just a Hickling phenomenon? Or is it a Thurne Broads system-wide effect

Palaeolimnological assessment of lake acidification and environmental change in the Athabasca Oil Sands Region, Alberta

13 páginas, 8 figuras, 4 tablas.Exploitation of the Athabasca Oil Sands has expanded hugely over the last 40 years. Regional emissions of oxidised sulphur and nitrogen compounds increased rapidly over this period and similar emissions have been linked to lake acidification in other parts of North America and Europe. To determine whether lakes in the region have undergone acidification, 12 lakes within the Regional Municipality of Wood Buffalo and the Caribou Mountains were selected to cover chemical and spatial gradients and sediment cores were obtained for palaeolimnological analyses including radiometric dating, diatom analysis, isotopic analysis of bulk sediment 13C and 15N, and spheroidal carbonaceous particles (SCPs). All lake sediment cores show evidence of industrial contamination based on SCPs, but there is no clear industrial signal in stable isotopes. Most lakes showed changes in diatom assemblages and sediment C:N ratios consistent with nutrient enrichment over various timescales, with potential drivers including climatic change, forest fires and anthropogenic nitrogen deposition. Only one of the 12 lakes investigated showed strong evidence of acidification with a decline in diatom-inferred pH from 6.3 to 5.6 since 1970 linked to increasing relative abundances of the acidophilous diatom species Actinella punctata, Asterionella ralfsii and Fragilariforma polygonata. Analysis of mercury (Hg) in the acidified lake showed increasing sediment fluxes over the last 20 years, a possible indication of industrial contamination. The acidified lake is the smallest of those studied with the shortest residence time, suggesting a limited capacity for neutralisation of acid inputs in catchment soils or by inlake processes.This work was funded by the NOx SOx Management Working Group of the Cumulative Environmental Management Association.Peer reviewe

Land-Use Experiments in the Loch Laidon Catchment

This report presents the results from the Stream Water Quality component of the Loch Laidon catchment land-use experiment which commenced in 1992. The experiment was established with the aim of examining the effects of cattle grazing on the aquatic and terrestrial habitats and biota of a moorland area of upland Scotland

Natural archives of long-range transported contamination at the remote lake Letšeng-la Letsie, Maloti Mountains, Lesotho

Naturally accumulating archives, such as lake sediments and wetland peats, in remote areas may be used to identify the scale and rates of atmospherically deposited pollutant inputs to natural ecosystems. Co-located lake sediment and wetland cores were collected from Letšeng-la Letsie, a remote lake in the Maloti Mountains of southern Lesotho. The cores were radiometrically dated and analysed for a suite of contaminants including trace metals and metalloids (Hg, Pb, Cu, Ni, Zn, As), fly-ash particles, stable nitrogen isotopes, polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants such as polychlorinated biphenyls (PCBs), polybrominated flame retardants (PBDEs) and hexachlorobenzene (HCB). While most trace metals showed no recent enrichment, mercury, fly-ash particles, high molecular weight PAHs and total PCBs showed low but increasing levels of contamination since c.1970, likely the result of long-range transport from coal combustion and other industrial sources in the Highveld region of South Africa. However, back-trajectory analysis revealed that atmospheric transport from this region to southern Lesotho is infrequent and the scale of contamination is low. To our knowledge, these data represent the first palaeolimnological records and the first trace contaminant data for Lesotho, and one of the first multi-pollutant historical records for southern Africa. They therefore provide a baseline for future regional assessments in the context of continued coal combustion in South Africa through to the mid-21st century

Freshwater umbrella - the effects of nitrogen deposition on freshwaters in the UK

In upland areas of the UK located away from direct human disturbance through agriculture, industrial activities and urban pollution, atmospheric pollution poses one of the major threats to the chemical and biological quality of lakes and streams. One of the most important groups of pollutants is nitrogen (N) compounds, including oxidised forms of N called NO_{x}, generated mainly by fossil fuel combustion especially in motor vehicles, and reduced forms of N (ammonia gas or dissolved ammonium compounds) generated mainly from agricultural activities and livestock. These nitrogen compounds may dissolve in rain or soilwater to form acids, or may be taken up as nutrients by plants and soil microbes in upland catchments, and then subsequently released in acid form associated with nitrate leaching at a later date. It is well established that nitrate leaching contributes to acidification of upland waters, with damage to aquatic ecosystems including plants, invertebrates and fish. However it has recently been suggested that nitrate leaching may also be associated with nutrient enrichment of upland waters that contain biological communities adapted to very low nutrient levels. Furthermore, important interactions have been found elsewhere between acid deposition and leaching of dissolved organic carbon (DOC) which has been found to be increasing in many upland waters of the northern hemisphere