Severe photobiont injuries of lichens are strongly associated with air pollution

The photobiont ultrastructure of the epiphytic lichens Bryoria fuscescens and Bryoria fremontii was studied along the pollution gradient from two Cu-Ni smelters in Nikel and Monchegorsk in northern Finland and north-western Russia. The relationship between ultrastructural characteristics of B. fuscescens and environmental factors (i.e. climate, atmospheric SO₂ and bark element concentrations) was studied by using a principal component analysis (PCA) aiming to assess the air quality in a northern environment. Based on PCA, increased plasmolysis and mitochondrial changes in the Trebouxia photobiont were significantly correlated with elevated pollutant concentrations. Degenerated cells, showing altered chloroplasts and electron-translucent pyrenoglobuli, occurred in lichens growing 35–50 km from the Monchegorsk smelter. Cell wall and cytoplasmic lipid volumes, and size of pyrenoglobuli, positively correlated with the distance from the Monchegorsk smelter. Vacuoles and electron-opaque vacuolar deposits were significantly increased at the Finnish site in the vicinity of a pulp mill. Swelling of mitochondrial cristae and thylakoids showed little correlation with environmental factors, but indicated of initial stage of injuries and were observed at several slightly polluted sites in northern Finland and north-western Russia. The results suggest that the severe photobiont injuries of lichens are strongly associated with poor air quality.     

Surface hydrophobicity causes SO2 tolerance in lichens

BACKGROUND AND AIMS: The superhydrophobicity of the thallus surface in one of the most SO(2)-tolerant lichen species, Lecanora conizaeoides, suggests that surface hydrophobicity could be a general feature of lichen symbioses controlling their tolerance to SO(2). The study described here tests this hypothesis. METHODS: Water droplets of the size of a raindrop were placed on the surface of air-dry thalli in 50 lichen species of known SO(2) tolerance and contact angles were measured to quantify hydrophobicity. KEY RESULTS: The wettability of lichen thalli ranges from strongly hydrophobic to strongly hydrophilic. SO(2) tolerance of the studied lichen species increased with increasing hydrophobicity of the thallus surface. Extraction of extracellular lichen secondary metabolites with acetone reduced, but did not abolish the hydrophobicity of lichen thalli. CONCLUSIONS: Surface hydrophobicity is the main factor controlling SO(2) tolerance in lichens. It presumably originally evolved as an adaptation to wet habitats preventing the depression of net photosynthesis due to supersaturation of the thallus with water. Hydrophilicity of lichen thalli is an adaptation to dry or humid, but not directly rain-exposed habitats. The crucial role of surface hydrophobicity in SO(2) also explains why many markedly SO(2)-tolerant species are additionally tolerant to other (chemically unrelated) toxic substances including heavy metals.     

Effects of heavy metal soil pollution and acid rain on growth and water use efficiency of a young model forest ecosystem

In a 4-year lysimeter experiment, we investigated the effects of topsoil heavy metal pollution (3,000 mg kg⁻¹ Zn, 640 mg kg⁻¹ Cu, 90 mg kg⁻¹ Pb and 10 mg kg⁻¹ Cd) and (synthetic) acid rain (pH 3.5) on tree growth and water use efficiency of young forest ecosystems consisting of Norway spruce (Picea abies), willow (Salix viminalis), poplar (Populus tremula) and birch (Betula pendula) trees and a variety of understorey plants. The treatments were applied in a Latin square factorial design (contaminated vs uncontaminated topsoil, acidified rain vs ambient rain) to 16 open-top chambers, with 4 replicates each. Each open-top chamber contained two lysimeters, one with a calcareous, and the other with acidic subsoil. The four tree species responded quite differently to heavy metal pollution and type of subsoil. The fine root mass, which was only sampled at the end of the experiment in 2003, was significantly reduced by heavy metal pollution in P. abies, P. tremula and B. pendula, but not in S. viminalis. The metal treatment responses of above-ground biomass and leaf area varied between years. In 2002, the heavy metal treatment reduced above-ground biomass and leaf area in P. tremula, but not in the other species. In 2003, metals did not reduce above-ground growth in P. tremula, but did so in the other species. It appears that the responses in above-ground biomass and leaf area, which paralleled each other, were related to changes in the relative competitive strength of the various species in the two experimental years. S. viminalis gained relative to P. tremula in absence of metal stress, in particular on calcareous subsoil, while P. abies showed the largest increases in growth rates in all treatments. Above- and below-ground growth was strongly inhibited by acidic subsoil in S. viminalis and to a lesser degree also in P. abies. In P. abies, this subsoil effect was enhanced by metal stress. Acid rain was not found to have any substantial effect. Whole-system water use efficiency was reduced by metal stress and higher on calcareous than on acidic subsoil.     

The acid drops project: pollution monitoring by young people

The spectrum of research at the Field Studies Council spans generations of scientists, from fully qualified and experienced staff to quite young children engaged in serious environmental monitoring. Pollution monitoring networks run by young people have a proven history, starting in 1971 with the Advisory Centre for Education air and water surveys, up to the present day with the Watch/Field Studies Council acid rain projects. Each project has demonstrated how a well coordinated network of unqualified volunteers, using inexpensive kits and simple techniques, can produce data worthy of scientific attention.     

广州市酸雨成分及其相关分析

分析了2003年11月-2004年10月广州市龙洞79次降雨的化学组分及其各组分之间的相关关系。得出:(1)观测期间总降雨量1359.8,单次降雨的pH值在3.22-7.29之间,平均4.83;以pH<5.6为酸雨的临界值,则酸雨频率占降雨次数的77.2%或占降雨量的81.5%;(2)广州降水的化学组成以SO₄^2-、Cl^-和NO₃^-为主要阴离子,阳离子中以Ca²⁺、NH₄⁺、Na⁺所占比例较大;(3)广州地区酸雨属硫酸型,降雨中的SO₄^2-、NO₃^-、PO₄^3-、Cl^-、NH₄⁺、K⁺、Na⁺、Ca²⁺、Mg²⁺离子浓度分别为0.150,0.045,0.002,0.163,0.058,0.006,0.013,0.083和0.007mol·L^-1,单次降雨的SO₄^2-/NO₃^-比值在0.42-17.6之间,年平均为3.33,该值比西南地区相应值低许多,而且与同一地点5年前测定的结果相比较,SO₄^2-/NO₃^-比值有变小的趋势,说明广州地区NO_x排放量高逐渐增加;(4)广州地区酸雨有着明显的季节变化规律,春、夏、秋季酸雨比较严重,冬季酸雨较少出现,这与西南地区的重庆(冬季酸雨较春季严重)酸雨季节规律相反;(5)通过SPSS统计分析得出,雨量与各化学组分含量成负相关,说明雨量对大气污染物质的稀释作用;酸雨各化学成分之间存在着一定的相关性,如SO₄^2-与Ca²⁺,NO₃^-与NH₄⁺,K⁺与Na⁺、Mg²⁺离子,Na⁺与Mg²⁺等都存在显著的正相关,利用这种相关可以建立某些酸雨成分的预测模型。     

Air pollution by SO2 amplifies the effects of water stress on enzymes and total soluble proteins of spruce needles

Measurements of soluble protein levels and catalytic capacity (maximum extractable activity) of isocitrate, glucose-6-phosphate and glutamate dehydrogenases were performed in needles of Picea abies L. Karst. under phytotron-controlled conditions in filtered or SO₂ polluted (0.08 ppm, 3.1 μmol m⁻³) air. In watered plants, pollution had no significant effects, although sulphur accumulated in the needles. Water deprivation (1 or 2 weeks depending on the experiments) of non-polluted plants decreased protein concentration and modified enzyme capacity, particularly for isocitrate and glucose-6-phosphate dehydrogenases. These effects were amplified in the polluted plants. Visible damage occurred only in plants subjected to both pollution and water stress. The results indicate that in spruce needles vulnerability of cell metabolism to the effects of a drought period is increased when water deprivation occurs under SO₂ pollution.     

Acid deposition in Snowdonia, North Wales

GRITTEN, R. H., 1992. Acid deposition in Snowdonia, North Wales. It has come as something of a surprise that the Snowdonia National Park, one of the least polluted areas in Europe, is suffering from the effects of acid deposition. A high annual rainfall and a hard geology combine to make the area vulnerable to wind-blown pollutants. The most sensitive ecosystems in the area are lakes and rivers which, showing signs of acid stress, are suffering diminishing salmonid and macroinvertebrate faunas. Upland populations of dippers also appear to be at risk and there is much evidence to show that coniferous afforestation is exacerbating the problems of acidification. There are indications that both broadleaved and coniferous trees are being damaged by acid deposition and certain upland plant communities are at risk. The possible effects on human health are also very worrying. It is the job of the National Park Authority to preserve the landscape of Snowdonia. How do we protect it from acid deposition?     

Effects of sulphur dioxide on leaf photosynthesis: the role of temperature and humidity

The effect of temperature and humidity on SO₂–induced photosynthetic depression was determined in gas exchange experiments with leaves of Vicia faba , L. Stomatal behaviour was sensitive to humidity resulting in higher uptake rates of SO₂ and stronger reductions of photosynthesis at low VPD (vapour pressure deficit). After a fumigation period of 2 h, when the photosynthetic rate had stabilized, photosynthesis of leaves exposed to SO₂ at 8°C was reduced much more than at 18°C at the same rate of SO₂ uptake. Data analysis with a mechanistic model revealed that this effect was due to the slower rate of S(IV) oxidation at lower temperatures, resulting in higher accumulation of S(IV) and thus stronger reduction of photosynthesis. These results were confirmed by experimental analyses of the S(IV) concentration in leaves following fumigation, which showed that more S(IV) accumulated in leaves exposed at a lower temperature. This may explain the high sensitivity of plants exposed to SO₂ under winter conditions, when both VPD and temperature are low.     

Biston betularia (the peppered moth) in West Kirby, Wirral, 1959–1989: updating the decline in f. carbonaria

Since 1985 the fall in carbonaria has continued and in 1989 it reached 29.6%. It is surmised that carbonaria will be down to mutant values by about the year 2010.