John Derome

Effects of heavy metal contamination on macronutrient availability and acidification parameters in forest soil in the vicinity of the Harjavalta CuNi smelter, SW Finland

Four experiments were established (1992) in Scots pine stands at distances of 0.5, 2, 4 and 8 km along a line running to the SE of the Cu-Ni smelter at Harjavalta, SW Finland, in order to investigate the effects of Cu and Ni emissions on macronutrient availability and estimates of cation exchange capacity (CEC) and base saturation (BS). The accumulation of Cu and Ni (total, exchangeable) in forest soil close to the smelter has resulted in a deficit of base cations (exchangeable Ca, Mg, K and BS) in the organic layer caused by inhibition of mineralisation and the displacement of base cations from cation exchange sites by Cu and Ni cations. No signs of soil acidification were found in the topmost layers of the soil measured as a change in pH, exchangeable acidity and Al. The determination of CEC by the summation method in heavy-metal polluted forest soils is not recommended unless heavy metal cations are also included in the calculations.

Metal and macronutrient fluxes in heavy-metal polluted Scots pine ecosystems in SW Finland

Abstract Cu, Ni, Zn, SO 4 –S and macronutrient fluxes in Scots pine ecosystems were investigated during 1992–1996 at distances of 0.5, 4 and 8 km from the Harjavalta Cu–Ni smelter, SW Finland. The flux of water percolating down to a soil depth of 5 cm at 0.5 km was more than double that at 4 and 8 km. There was a net loss of Zn from the 40-cm thick soil layer, but a net gain for Cu, Ni and SO 4 –S. Copper was more strongly retained in the organic layer than Ni. Cu, Ni and Zn fluxes at 0.5 km were extremely large compared to those at 4 and 8 km. The fluxes of Ca, Mg, K and PO 4 –P to a depth of 5 cm at 0.5 km distance were much higher than the input via bulk precipitation, and the flux of Mg higher than the input in throughfall. There was a net loss of Mg and K at a depth of 40 cm compared to the input via bulk precipitation.

Effects of Nitrogen Inputs on Forest Ecosystems Estimation Based on Long-Term Fertilization Experiments

The material consists of 40 fertilization experiments in Scots pine and Norway spruce stands. The total amount of nitrogen applied during a 20-year period averages 315 kg ha- 1, which is equivalent to the total atmospheric nitrogen load in central Finland during a single rotation period according to current deposition levels.

Understorey vegetation along a heavy-metal pollution gradient in SW Finland

Understorey vegetation of Scots pine forests was studied along a 8-km transect running SE from a Cu-Ni smelter at Harjavalta, SW Finland. Long-term accumulation of heavy metals and sulphur in the forest ecosystem has drastically changed plant communities. Vegetation was almost absent up to a distance of 0.5 km from the smelter. The total coverage and the number of plant species increased with increasing distance from the smelter. Ordination by global non-metric multidimensional scaling (GNMDS) indicated that the floristic composition was differentiated in response to the pollution level. The main compositional gradient of GNMDS was correlated with the heavy metal concentrations in the organic soil layer and with the size of the overstorey trees. Vascular plants were more pollution-resistant than ground lichens, whereas mosses were the most sensitive plant group. In addition to heavy metals, nutrient imbalances and the considerably reduced water-holding capacity of the surface soil also restrict plant recolonisation on the degraded sites.

Compensatory fertilization of Scots pine stands polluted by heavy metals

The results from four compensatory fertilization experiments located at different distances (0.5, 2, 4 and 8 km) along a heavy metal deposition gradient extending from the Harjavalta Cu-Ni smelter in SW Finland are presented. The experiments were established in middle-age Scots pine stands growing on dryish sites of sorted glaciofluvial sediments. The soil type in all the experiments is ferric podsol. The treatments in the experiments consisted of liming, a powdered slow-release mineral mixture and stand-specific fertilization which comprised at least methylene urea and ammonium nitrate.Monitoring of deposition and soil solution and studies on soil chemical and microbiological properties, on the nutrient status of trees and needle litterfall, on fine root dynamics and on the growth of the tree stands were carried out during a 5-year period.There was a severe shortage of exchangeable Ca and Mg in the organic layer of the most polluted stands. Although the uppermost mineral soil layer had relatively high exchangeable Ca and Mg concentrations, the trees were not able to utilize these nutrient reserves presumably due to the toxic effects of Cu and Ni on the plant roots and mycorrhizas.The treatments that included limestone markedly decreased the Cu and Ni concentrations in the soil solution and soil organic layer, presumably due to immobilisation through precipitation or absorption. The Ca and Mg concentrations correspondingly increased, which certainly contributed to the partial recovery of fine root and stand growth. The powdered mineral mixture and the combination of methylene urea and ammonium nitrate had no short-term effect on the microbial biomass and activity. All the fertilizer treatments increased volume growth in the most polluted stand. The stand-specific fertilization increased needle mass in heavily polluted stands, but the response of the needle mass to fertilizer treatments was low in the less polluted stands. No clear evidence was found to support the role of nutrient status in tree resistance.

Ectomycorrhizal root tips in relation to site and stand characteristics in Norway spruce and Scots pine stands in boreal forests

Variations in ectomycorrhizal (EcM) short root tips of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) in 16 stands throughout Finland were studied, and their relationships with latitude, organic layer C:N ratio, temperature sum and foliage biomass were determined. There were no significant differences in EcM root tip frequency (number per milligram of fine roots) or root tip mass between tree species or between northern and southern sites. The EcM root tip number per unit area of the organic layer plus the 0-30 cm mineral soil layer varied between 0.8 and 2.4 million per m(2) for Norway spruce and between 0.7 and 2.9 million per m(2) for Scots pine, and it was higher in the northern Scots pine stands than in the southern Scots pine stands. Over 80% of the EcM root tips of both species were in the organic layer and the upper 0-10 cm mineral soil layer. We related EcM root tips to foliage mass because these two components are the most important functional units in boreal tree physiology. Both species, especially the Scots pine trees, had more EcM root tips in relation to foliage mass in northern Finland than in southern Finland. Scots pine trees had more EcM root tips in relation to foliage mass than Norway spruce in the same climatic region. The EcM root tip:foliage biomass ratio of Norway spruce was positively related to the C:N ratio in the organic layer, whereas that of Scots pine was negatively related to the temperature sum. The number of EcM root tips per milligram of fine root biomass was constant, implying that trees of both species increase nutrient uptake by increasing fine root production and hence their total number of EcM tips and the area of soil occupied by mycelia. Both tree species responded to nitrogen (N) deficiency by maintaining more EcM tips per foliage unit, and this may be related to a higher proportion of N uptake in an organic form.

Detoxification and amelioration of heavy-metal contaminated forest soils by means of liming and fertilisation

Four experiments were established in 1992 in Scots pine stands (Pinus sylvestris L.) on relatively infertile sites at distances of 0.5, 2, 4 and 8 km to the south-east of the Cu-Ni smelter at Harjavalta, south-west Finland, in order to investigate the effects of liming, correction fertiliser and site-specific fertiliser treatments on heavy metal (Cu, Ni) and macronutrient (Ca, Mg, K) availability in the organic layer. The organic layer samples were analysed for total, plant-available (BaCl(2)+EDTA) and water-extractable Ca, Mg, K, Cu and Ni. A high proportion of the Cu and Ni at 0.5 km was in a non-toxic, immobilised form. Liming had only a relatively small reducing effect on free and exchangeable Cu and Ni concentrations at 0.5 km. The lack of pH increase following liming may be due to the precipitation of Fe, present in very high concentrations close to the smelter, as Fe(OH)(3), resulting in the loss of neutralising bicarbonate and hydroxyl ions, but the release of Ca and Mg. Liming strongly increased Ca and Mg availability. The correction fertiliser had no effect on Ca or K availability at any of the sites.

Organic material as a copper immobilising agent: a microcosm study on remediation

Remediation of heavy metal polluted forest soil was studied using nine different organic immobilising agents in a laboratory microcosm study. Composted sewage sludge, compost of organic household waste, a mixture of compost and woodchips, a mixture of compost and barkchips, garden soil, birch leaves, barkchips, humus or peat was applied on the surface of a polluted soil. Changes in the exchangeable Cu concentration, microbial respiration activity, microbial biomass and structure of the microbial community were assessed at four points during a 16-month period. Cu fractions, Cu 2+ and complexed Cu, and toxicity of the soil solution to bacteria, bacterial growth rate, number of bacterial cells, and bacterial copper tolerance were determined on samples taken after 16 months. Sewage sludge, compost, the compost mixtures, and garden soil decreased the exchangeable Cu concentration in the polluted soil, but had no effect on microbial activities, bacterial tolerance to copper or on the structure of the microbial community directly attributable to remediation. Zur Remediation von Schwermetall belasteten Waldboden wurden in einem Mikrokosmosversuch neun verschiedene Schwermetall immobilisierende organische Substanzen getestet. Klarschlamm, Haushaltskompost, eine Mixtur von Haushaltskompost und Holzspanen, eine Mixtur von Haushaltskompost und Rindenspanen, Gartenerde, Birkenblatter, Rindenspane, Humus oder Torf wurde einem belasteten Waldboden als neue organische Schicht aufgetragen. Uber den 16 Monate lang andauernden Laborversuch haben vier Beprobungen stattgefunden und die Konzentration von austauschbaren Cu, die Mikrobielle Respiration, die Mikrobielle Biomasse, und die Zusammensetzung der Bodenmikroflora wurden jeweils bestimmt. Zusatzlich wurden bei der letzten Beprobung (16 Monate) auch zwei verschiedene Cu Fraktionen, Cu ++ und komplekziertes Cu, die Toksizitat des Bodenwassers gegenuber Bakterien, die Bakterielle Wachstumsrate, die Bakterienanzahl und die Tolreranz der Bakterien gegen Cu bestimmt. Die Auftragung von Klarschlamm, Kompost, der beiden Kompostmixturen oder Gartenerde auf die Bodenoberflache erniedrigte die Konzentration von austauschbaren Cu des Bodens aber hatte keine lang anhaltenden Remedierungsefekte auf die Bodenbiologie des Schwermetal belasteten Waldbodens.

Element distribution in Empetrum nigrum microsites at heavy metal contaminated sites in Harjavalta, western Finland.

Small-scale element distribution in soil-plant-systems in patches of Empetrum nigrum (microsites) at heavy metal contaminated sites located 0.5 and 4 km from the copper-nickel smelter at Harjavalta was investigated. The Cu concentrations of E. nigrum varied between 12 and 2300 mg/kg dw and showed increasing accumulation with increasing tissue age. Stems contained more Cu than leaves of the same age. The distribution pattern of Ni and Pb in the above-ground biomass followed that of Cu. Roots contained relatively low concentrations of all airborne heavy metals. In the soil, the highest concentrations of total Cu occurred in the humus (Oh) layer: on average 49,450 mg/kg dw at 0.5 km distance and 12,025 mg/kg dw at 4.0 km. Despite the extremely high Cu concentrations in the topsoil, the concentrations in the mineral soil below a depth of 10 cm did not exceed 2.5 mg/kg dw at any site.

Simple procedure for ion chromatographic determination of anions and cations at trace levels in ice core samples

Several suppressed and non-suppressed ion chromatography (IC) elution systems were compared for the determination of ng ml ˇ1 levels of major cations and anions, including formate and methyl sulphonate, in ice core samples using a small (0.2‐ 0.8 ml) sample volume. The use of a suppression unit considerably enhanced the sensitivity of the anion determinations, but had no remarkable effect on the sensitivity of the cation determinations. Optimized analytical conditions were further validated in terms of accuracy, precision and total uncertainty and the results showed the reliability of the IC methods. In addition, contamination problems associated with handling the ice core were investigated, and a simple and almost contamination free ice handling procedure is presented. # 1999 Elsevier Science B.V. All rights reserved.