Concentrations,Cumulative Exposure and Critical Levels of Ozone in Ireland

Concentrations of tropospheric ozone(O₃) and exceedance of critical levels to vegetationhave been investigated and mapped for Ireland. Hourlyozone concentration data (1995–1997) at 7 sevenmonitoring stations and the CORINE landcover database,supported by a Geographical Information System, wereused. AOT40 (Accumulated exposure Over a Threshold of 40ppb) was calculated for daylight hours for each station,and mapped using surface interpolation. Average O₃concentrations vary from year to year, and were estimatedto be 28 ppb, 26 ppb and 24 ppb for 1995, 1996 and 1997respectively. Ozone concentrations show a large diurnalvariation, with a maximum in the afternoon and a minimumat night-time. The critical level for crops and (semi-)natural vegetation was exceeded in all years examined.The highest exceedance occurred in 1995, where thecritical level was exceeded for almost 35% of the mappedarea. Approximately 15% and 1% of the mapped area wasexposed to exceedance levels during 1996 and 1997respectively. The maximum cumulative exposures (AOT40)were approximately 5000, 3890 and 3230 ppbh in 1995, 1996and 1997 respectively. The critical level for forests wasnot exceeded during the period of investigation.     

Reconstruction of Long-Term Changes in Lake water Chemistry,Zooplankton and Benthos of a Small,Acidified High-Mountain Lake: Magic Modelling and Palaeolimnogical Analysis

Starolesnianske pleso is a small and shallow acid lake in the High Tatra Mountains, situated at 2000 m above sea level, on granitic bedrock, with sparse and thin soil cover. When detailed measurements began in the 1980s Starolesnianske pleso had pH below 5 and only one species of cladoceran zooplankton, the ubiquitous Chydorus sphaericusPalaeolimnological investigations show changes in cladoceran zooplankton and chironomid zoobenthic assemblages since about 1920 and a major change in 1970–1980. The dynamic acidification model MAGIC was used to reconstruct changes in water chemistry over the past 150 years. The results from MAGIC agree well with the sediment record; pH levels gradually decreased from 6.5 in the mid-1800s to about 5.6 in 1920 (first response in biota) to below 5.0 by 1970, and concentrations of inorganic aluminium rose dramatically beginning about 1960. In the 1990s the lake water chemistry showed clear signs of reversal in acidification brought about by a major decline in S deposition.     

Use of Natural 35S to Trace Sulphate Cycling in Small Lakes,Flattops Wilderness Area,Colorado, U.S.A.

Measurements of the cosmogenically-produced ³⁵S, a radioisotope of sulphur (t_1/2 = 87 days), are reported for the Ned Wilson Lake watershed in Colorado. The watershed contains two small lakes and a flowing spring presumed to be representative of local ground water. The watershed is located in the Flattops Wilderness Area and the waters in the system have low alkalinity, making them sensitive to increases in acid and sulphate deposition. Time series of ³⁵S measurements were made during the summers of 1995 and 1996 (July–September) at all three sites. The system is dominated by melting snow and an initial concentration of 16–20 mBq L^-1 was estimated for snowmelt based on a series of snow samples collected in the Rocky Mountains. The two lakes had large initial ³⁵S concentrations in July, indicating that a large fraction of the lake water and sulphate was introduced by meltwater from that year's snowpack. In 1995 and 1996, ³⁵S concentrations decreased more rapidly than could be accounted for by decay, indicating that other processes were affecting ³⁵S concentrations. The most likely explanation is that exchange with sediments or the biota was removing ³⁵S from the lake and replacing it with older sulphate devoid of ³⁵S. In September of 1995 and 1996, ³⁵S concentrations increased, suggesting that atmospheric deposition is important in the sulphate flux of these lakes in late summer. Sulphur-35 concentrations in the spring water were highly variable but never higher than 3.6 mBq L^-1 and averaged 2 mBq L^-1. Using a simple mixing model, it was estimated that 75% of the spring water was derived from precipitation of previous years.     

Response of Drinking-water Reservoir Ecosystems to Decreased Acidic Atmospheric Deposition in SE Germany: Signs of Biological Recovery

Strongly decreasing atmospheric emissions and acidic deposition during the 1990s have initiated chemical reversal from acidification in several drinking-water reservoirs of the Erzgebirge, SE Germany. We studied responses of phytoplankton, zooplankton and fish stocks in five reservoirs and at enclosure scale after experimental neutralization of 1,200 m³ of lake water. About 4 months after this treatment, diatoms and cryptomonads replaced the predominating chrysophytes and dinoflagellates. The colonization by acid-sensitive species of green algae, cryptomonads, rotifers and Cladocera (e.g. Bosmina longirostris) is explained by the occurrence of dormant stages or by survival of individuals in very low abundances. Analogous to the enclosure experiment, three reservoirs showed significantly (p < 0.01) falling trends of chlorophyll a and phytoplankton biovolume, mainly due to the decline of dinoflagellates. Picoplankton and diatoms increased slightly in two reservoirs. The zooplankton communities were dominated by rotifers and small Cladocera. Representatives of the genus Daphnia were lacking. Two reservoirs were re-colonized by zooplanktivorous fish populations of either perch (Perca fluviatilis) or sunbleak (Leucaspius delineatus). The latter exhibited extremely high fluctuating abundance and biomass and even suffered from a population crash. This natural mortality was caused by a limited food supply. Hence, severe top-down control may delay the recovery of larger zooplankton species like daphnids. Fishery management comprising the introduction of predatory fishes can help to control zooplanktivorous fish populations and to prevent their mass mortality.     

Forest Decline Evidence in Southern Turkey and its Possible Dependence on Ozone Trends

During the period between 1991 and 1997, crown condition was monitored at an experimental forest located in Southern Turkey, near Antalya. In order to determine the nutritional status of the stands in the study area, in the years 1992, 1993 and 1998, young and old needles were collected from the labelled trees and nutrient contents (N, P, K, Ca, Mg) of the needles were determined. Between the years 1991 and 1997, the degree of defoliation of the canopies, according to the damage indexes, changes from 10–25% to 25–60%. Between the years 1992 and 1998, examination of nutrition condition of the stands reveal that, sufficient and balanced nutrition status of the trees in the year 1992, becomes insufficient or unbalanced for P, K, and N in 1998.From October 1994 to January 1996, a continuous hourly ozone sampling was performed on the Mediterranean coast of Turkey (30.34°E, 36.47°N) near Antalya. The survey carried out in the summer of 1995 reveals that AOT40_f index is 14.612 ppm.h, which exceeds the critical level of 10 ppm.h. As the measured ambient ozone levels are higher than critical level, it has been proposed that ozone may be one of the anthropogenic stress factors causing the forest decline in Southern Turkey observed within this study.     

Epilithic Diatoms in an Alpine Lake (Traunsee,Austria) Affected by Soda and Salt Mining Industries

Traunsee, a 191 m deep Alpine lake in Austria, is affected by industrial tailings from the soda and salt mining industries since 1883. In 1998 littoral water chloride concentrations ranged between 40 and 85 mg L^-1 and the highest conductivity was 560 S cm^-1, which is almost double as high as the values reported from the two nearby reference lakes. Chloride concentrations increased towards the location of the industrial salt and soda emission into the lake. Analogously to the chloride gradient, the epilithic littoral diatom flora changes towards the waste inlet. Shifts in the species percentages towards the emission source, a high percentage of taxa with large conductivity tolerances, the presence of a small Achnanthes minutissima Kützing morphotype, and occurrences of taxa focused at habitats of higher electrolyte content, indicate subtle impacts on the epilithic diatom flora. An analysis of the seasonal succession of the epilithic diatoms at the waste inlet compared to a lake intern reference site, reveals that only during the late summer period in 1998 the diatom assemblage at the waste inlet became significantly different, indicating seasonally restricted effects of the industrial emissions.     

Invasives, Introductions and Acidification: The Dynamics of a Stressed River Fish Community

We describe the development of the fish community in the acidified and limed river Litleåna in southern Norway, and describe how chemical restoration, compensatory introductions of exotics, and accidental invasion of exotics interact to influence the population of the naturally occurring brown trout (Salmo trutta). The river Litleåna is a tributary to the river Kvina in Vest-Agder County, southern Norway. During the years 1996–2004, annual mean pH was 4.9–5.0 and 6.1–6.4 above and below the liming facility, which was installed in 1994. Originally, brown trout was the only fish species in the river, but brook trout (Salvelinus fontinalis) have been intentionally introduced, whereas European minnow (Phoxinus phoxinus) was introduced by accident. Fish densities were recorded by means of electrofishing annually over the ten year period 1995–2004. Although close to extinction before liming was initiated, brown trout fry densities increased from 1995 to 1999, with subsequent varying densities. There has been a simultaneous major increase in the occurrence and density of European minnow since 1997. Our results show that both brown trout and European minnow increase after liming. Minnow densities are negatively affected by low pH episodes in the river. The growth rates of brown trout fry are negatively correlated to minnow densities, indicating competition between the species. Brook trout densities have decreased since liming started, and during the brown trout recovery.     

The Effects of Three Thermo Electric Power Plants on Yerkesik-Denizova Forests in Mugla Province (Turkey)

Mugla is a city that is located in the southwest part of Turkey. Three thermo-electric power plants called Yatagan (3 × 210 MW) and Yenikoy (2 × 210 MW)and Kemerkoy (Gokova, 3 × 210 MW) havebeen constructed in this region and also have begun operation in 1982 – 1983 – 1984 (three units), in 1988 and in 1995, respectively. The Pinus brutia forests in Yerkesik–Denizova region have been under the common effects of Yenikoy and Yatagan thermo-electric power plants. Therefore, these Pinus brutia forests have startedto dry in groups since 1988. In addition, Kemerkoy thermo-electric power plant, began operation in 1995.Polluting gases arrived in Denizova-Yerkesik throughKoca Stream Valley Forests.Increasing quantities of polluting gases and especially SO₂ have dried the trees in large amounts in this 1650 ha forestland area. YataganThermo-electric power plant has caused drying of Pinus brutia in Bencik Mountain, which was on the south in 1984–1985. The same phenomenon was seen in Denizova-Yerkesik Forest in 1999–2000. It was observed that sulphur content was varying between 4218–6676 ppm at the Pinus brutia needle samples taken in this region on 16 December 2000. Sulphur contents were correlated with the age of needle (1–2 yr old), density of yellow stains on the needles and amount of drying needles. Particularly in 1996–2000 period, the destruction of chlorophyll in needles due to the impacts of SO₂ was also correlated with narrowing of the annual rings from one year to another. The narrowing ratio of yearly rings reached 60–504% for 94–95 yr old, and 375–661% for 58–63 yr old Pinus brutia trees during the 1986–1990, 1991–1995 and 1996–2000 periods.All these results clearly showed that the decrease in the chlorophyll content in needles under the effect of air pollution caused important reduction in the raw timber production and its inputs to the economy. In other words, drying due to increased ecological sensitivity or direct hazard of pollutants emitted by the power plants and cutting of trees have been notably increased in the region. This has created serious economic losses.     

Dynamics of Bacterial Abundance,Biomass, Activity,and Community Composition in the Oligotrophic Traunsee and the Traun River (Austria)

The holomictic Traunsee is the deepest and second largest lakein Austria. The special characteristic of this ecosystem isthe fact that local salt and soda industries presumably alterthe lake by the discharge of waste materials. Since thebeginning of the 20th century salt and soda works areannually releasing up to 50,000 tons of solid wastes and up to150,000 tons of chloride into Traunsee. To assess potentialeffects of these anthropogenic impacts on the bacterioplanktonthree sampling sites, influenced as well as not influenced bythe industrial discharge, were chosen for comparison andsampled monthly from November 1997 to October 1998. Bacterialabundance ranged between 0.4 to 3.0 × 10⁶ cells ml^-1 with decreasing numbers along the depth profile. Theproportion of actively respiring bacteria, i.e. INT [2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride]reducing cells, never exceeded 10% of DAPI (4',6'-diamidino-2-phenylindole) stained cells. Fluorescence in situ hybridization (FISH) was used to examine the seasonal and spatial distribution of dominant phylogenetic groups of thebacterioplankton. Up to 84% of bacteria detected with DAPIcould be detected via FISH applying the universal bacterialprobe EUB338. Percentages of alpha- and beta-Proteobacteriaand members of the Cytophaga-Flavobacterium cluster did notexceed 60% of DAPI-stained cells.Beta-Proteobacteriaappeared to be the most abundant group, not only in Traunsee butalso in two reference lakes, Attersee and Hallstättersee. No significant differences in any of the bacterial parameters couldbe detected between the three sampling sites and all measurementswere found in the range reported for oligotrophic lakes. The highdischarge of the Traun River, resulting in a lake water renewaltime of only one year, may diminish possible effects of industrial waste discharge in the pelagic zone.     

Distribution of Diatoms in a Forested Stream Containing a Series of Interconnected Lakes

We explored the spatial variation in diatom communities withinthe Turkey Lakes Watershed (TLW). The TLW is a single watershed in an old growth sugar maple forest that contains an alternatingseries of stream and lake embayments. Near the outlet of each lake, we sampled pools and riffles to determine abundance and diversity of diatom communities along this hydrologic system. Diatom diversity, measured by Shannon-Weaver Index, richness andevenness, increased steadily downstream before eventually decreasing near the watershed outlet. Canonical CorrespondenceAnalysis indicated that diatom genera were correlated with streamchemistry. Upper reaches were the least productive, characterizedby lower pH (<7), higher N:P (113:1 to 124:1, dominated by complex forms of N), and high mean relative abundances of Eunotia spp., Tabellaria spp., and Pinnularia spp. Middle and lower reaches were more productive, characterized byhigher pH (>7), lower N:P (71:1 to 90:1, dominated by simple forms of N, e.g., nitrate-N), and high mean relative abundances of Cymbella spp. and Brachysira spp. Achnanthesminutissima (Kutz.) Hustedt, the most abundant species, and Navicula spp., Nitzschia spp., Gomphonema spp., and Frustrulia spp. were represented at all stream sites. Thisstudy revealed that within the TLW, a hydrologic system of the same stream order, the diatom community was influenced by a nutrient gradient, where the stream and its intervening lakes contributed to a shift from acidic, inorganic N-poor upper reaches to a circum-neutral, inorganic N-richer outlet. By imparting genera-specific stresses, stream flow (i.e. pools vs. riffles) further shaped the diatom community.     

Finnish Lake Survey: The Role of Catchment Attributes in Determining Nitrogen, Phosphorus, and Organic Carbon Concentrations

This study is based on a Finnish lake survey conducted in 1995, a dataset of 874 statistically selected lakes from the national lake register. The dataset was divided into subgroups to evaluate lake water-catchment relationships in different geographical regions and in lakes of different size. In the three southernmost regions, the coefficients of determination in multiple regression equations varied between 0.40 and 0.53 for total nitrogen (TN) and between 0.37 and 0.53 for total phosphorus (TP); the best interpreters were agricultural land and water area in the catchment. In the two northernmost regions, TN concentrations in lake water were best predicted by the proportion of peatlands in the catchment, the catchment slope, and TP concentrations by lake elevation and latitude. Coefficients of determination in multiple regression equations in these northern regions varied between 0.39 and 0.67 for TN and between 0.41 and 0.52 for TP. For all the subsets formed, the best coefficients of determination explaining TN, TP, and total organic carbon (TOC) were obtained for a subset of large lakes (>10 km²), in which 72–83% of the variation was explained. This was probably due to large heterogeneous catchments of these lakes.     

Assessment of the Ecological Integrity of Traunsee (Austria) Via Analysis of Sediments and Benthic Microbial Communities

Since nearly one hundred years Traunsee experiences the import of tons of liquid and solid waste originating from salt and soda production. Today, the lake exhibits chloride concentrations of up to 170 mg L^-1 and 19% of the lake floor are directly or indirectly influenced by industrial deposits (ID). Based on the comparison of several microbial parameters in unaffected, directly affected and intermediate lake bottom sediments, the ecological integrity of the lake was evaluated. The highly alkaline ID, which were exclusively colonized by microorganisms, harbored a bacterial community reduced by a factor of 10 in abundance and biomass compared to undisturbed sediment areas within the lake. The bacterial community of ID was furthermore characterized by a reduced content of actively respiring cells (INT-formazan reduction), a lower frequency of dividing cells (FDC) and a significantly reduced cell and biomass production. A 80 to 90% reduction in carbon recycling is estimated for the area exclusively covered by ID. Protists, although occasionally absent from the industrial sediments, were in general found to be less sensitive to the contaminant stress. Differences in alkalinity and dissolved organic carbon (DOC) concentrations of sediment porewaters as well as the total organic content and C/N ratios of sediments partly explain the microbial pattern observed at the various sampling sites. Possible consequences of the continuous industrial tailings for the whole lake ecosystem and the validation of the ecological integrity are discussed.     

Protozooplankton in the Deep Oligotrophic Traunsee (Austria) Influenced by Discharges of Soda and Salt Industries

Traunsee is a deep oligotrophic lake in Austria characterised by an artificial enrichment of chloride in the hypolimnion (up to 170 mg L^-1) caused by waste disposal of soda and salt industries. Protists were collected monthly over one year, observed alive and after Quantitative Protargol Staining (ciliates) or via epifluorescence microscopy (heterotrophic flagellates). Three sites within the lake (0–40 m depths) were compared to deeper water layers from 60–160 m depths where chloride concentrations and conductivity were increased. In addition, we observed the protozooplankton of two neighbouring lakes, i.e. reference systems, during one sampling occasion. In Traunsee the abundance of ciliates was low (200–36 600 cells L^-1) in contrast to high species diversity (at least 60 different species; H_S = 2.6) throughout the year. The main pelagic species in terms of abundance were small oligotrichs and prostomatids like Rimostrombidium brachykinetum/hyalinum, Balanion planctonicum and Urotricha spp. throughout the investigation period. Among free-living heterotrophic flagellates, which occurred at densities of 40–2800 cells mL^-1, small morphotypes dominated in the pelagial. No differences at the community level between the three lakes could be observed and pelagic ciliates and flagellates seemed not to be affected by increased chloride concentrations or by enhanced conductivity.     

Translocation and Growth Experiments with the Macropohyte Potamogeton Lucens L. in Traunsee (Austria), with Respect to Industrial Tailings

The absence of Potamogeton lucens L. in an area of Traunsee, Austria, which is heavily impacted by industrial sludges was related to these deposits. The hypothesis that P. lucens L. is affected by the industrial tailings was confirmed by growth experiments of the translocated plants in the field. At the unpolluted reference site of the lake, the plants grew better, they were longer and produced more leaves than at the emission site.     

Effects of Decreased Atmospheric Heavy Metal Deposition in South Sweden on Terrestrial Birds and Small Mammals in Natural Populations

In southern Sweden, where exposure to long range distributedheavy metals is about the highest in Scandinavia, depositionsof cadmium (Cd) and lead (Pb) decreased about 20 and 70%,respectively, between mid-1980s and mid-1990s, as estimated bytheir concentrations in moss. Concentrations of Cd and Pb in tissues of the pied flycatcher (Ficedula hypoleuca) and bank vole (Clethrionomys glareolus) were also lower in 1996and 1997 compared to 1981 and 1982. It is concluded that the decreased deposition rate of these elements in southern Sweden had caused decreased exposure, and thus also to decreased potential risk of detrimental effects on insectivorous birds andherbivorous mammals. There was no indication that breeding results of pied flycatcher was influenced by the decreased deposition of toxic metals.     

Recycling and reuse of industrial wastes in Taiwan

Eighteen million metric tons of industrial wastes are produced every year in Taiwan. In order to properly handle the industrial wastes, the Taiwan Environmental Protection Administration (Taiwan EPA) has set up strategic programs that include establishment of storage, treatment, and final disposal systems, establishment of a management center for industrial wastes, and promotion of recycling and reuse of industrial wastes. The Taiwan EPA has been actively promoting the recycling and reuse of industrial wastes over the years. In July 1995 the Taiwan EPA amended and promulgated the Criteria for the Industrial Waste Storage, Collection and Processing Facility, July, 1995 that added articles related to general industrial waste recycling and reuse. In June 1996 the Taiwan EPA promulgated the Non-listed General Industrial Waste Reuse Application Procedures, June, 1996, followed by the Regulations Governing the Permitting of Hazardous Industrial Waste Reuse, June 1996, setting up a full regulatory framework for governing industrial waste reuse. To broaden the recycling and reuse of general industrial wastes, the Taiwan EPA has listed 14 industrial waste items for recycling and reuse, including waste paper, waste iron, coal ash, tempered high furnace bricks (cinder), high furnace bricks (cinder), furnace transfer bricks (cinder), sweetening dregs, wood (whole/part), glass (whole/part), bleaching earth, ceramics (pottery, brick, tile and cast sand), individual metal scraps (copper, zinc, aluminum and tin), distillery grain (dregs) and plastics. As of June 1999, 99 applications for reuse of industrial wastes had been approved with 1.97 million metric tons of industrial wastes being reused.     

The current situation of solid waste generation and its environmental contamination in China

In China, controlling environmental pollution resulting from solid waste (SW) and hazardous waste (HW) has become one of the most pressing tasks in the field of environmental engineering. It is reported that the annual generation of industrial solid waste (ISW) in China exceeded 0.6 billion tons in the 1990s, and is increasing every year. Although ISW management has been strengthened in recent years, about 40% of SW is put in uncontrolled landfill without appropriate treatment. According to statistics from the national Environmental Protection Agency, the cumulative ISW uncontrolled landfill in China had reached 6.6 billion tons by the end of 1995, occupying around 55 000 hectares of land. Although some major uncontrolled landfills were constructed, nonetheless groundwater contamination resulted from the use of low-standard liners and poor management. Furthermore, about 20 million tons of ISW was discharged into the environment illegally, and a third of this waste was discharged directly into water bodies, making ISW one of the greatest pollution sources for surface water and ground water. Environmental pollution accidents resulting from SW occur about 100 times a year in China, and environmental issues frequently arise because of ISW pollution. The practices of SW management, treatment, and disposal started relatively late in China, and for a long time the management of SW pollution has received little attention compared with water and air pollution management. China faces problems such as the insufficiency of management laws and regulations, insufficient investment, inadequate treatment and disposal technology, and a lack of qualified technicians. At present, most treatment and disposal technology cannot meet the requests for solid waste pollution control. In order to protect, restore, and improve environmental quality in China and to realize sustainable development, the safe management and disposal of solid and hazardous wastes is a pressing challenge. In recent years, much attention has been paid to SW management in China, and investment to develop management and treatment technologies has increased. In 1995, the Law for Solid Waste Pollution Protection was issued, and work on solid waste treatment and disposal began to be legally managed. SW treatment and disposal facilities have been constructed, and now operate in some large and medium-sized cities. In particular, rapid improvements have been seen in ISW recycling, collection, and disposal of municipal solid waste and regional HW management. All the figures in this paper are from 1995, and represent the situation in China in that year. Received: April 18, 2000 / Accepted: May 15, 2000     

Topographical imaging as a means of monitoring biodegradation of poly(hydroxyalkanoate) films

Poly(hydroxyalkanoates) (PHAs) are a class of bacterially-derived polymers that are naturally biodegradable through the action of extracellular depolymerase enzymes secreted by a number of different bacteria and fungi. In this paper we describe the development of topographical imaging protocols (by both scanning electron microscopy; SEM, and confocal microscopy; CM) as a means of monitoring the biodegradation of solution cast films of poly(3-hydroxybutanoate-co-3-hydroxyhexanoate) (P3HB/3HHx) and medium-chain-length (mcl-) PHA. Pseudomonas lemoignei and Comamonas P37C were used as sources for PHA depolymerase enzymes as these bacteria are known to degrade at least one of the polymers in question. SEM revealed the bacterial colonization of the film surfaces while CM permitted the comparative assessment of the roughness of the film surfaces upon exposure to the two bacterial strains. By dividing the total surface area of the film (A′) by the total area of the scan (A) it was possible to monitor biodegradation by observing differences in the topography of the film surface. Prior to inoculation, P3HB/3HHx films had an A′/A ratio of 1.06. A 24-h incubation with P. lemoignei increased the A′/A ratio to 1.47 while a 48- and 120-h incubation with Comamonas resulted in A′/A ratios of 1.16 and 1.33, respectively. These increases in the A′/A ratios over time demonstrated an increase in the irregularity of the film surface, indicative of PHA polymer breakdown. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

The Influence of Chironomus plumosus Larvae on Nutrient Fluxes and Phosphorus Fractions in Aluminum Treated Lake Sediment

One of the methods to diminish the internal phosphorus (P) loading is inactivation of P by aluminum (Al). After addition of Al to lake water an Al(OH)₃ floc is formed, which settles to the bottom and initially form a lid on the sediment surface. The effects of Chironomus plumosus larvae on sediment nutrient fluxes and P binding-sites in the sediment after addition of Al were tested. C. plumosus larvae were added to sediment cores in which sediment–water fluxes of nutrients were measured four times. After one month, the sediment was sectioned with depth and P fractions were measured by sequential chemical extraction. The chironomids created burrows through the Al layer which caused a significantly increased efflux of P from the Al treated sediment, because the P had only limited contact to the added Al. The chironomids also affected the P fractions in the sediment by their bioturbating activity. Thus, they caused increased Al concentrations in the upper part of the Al treated sediment. This created an enhanced contact between Al and P in the upper 7 cm of the sediment and, as a result, an increased binding of P to Al and a lowered porewater P. The DIP efflux is therefore expected to be lowered after the initial phase. Al had no effects on the nitrogen fluxes, but the chironomids enhanced the release, and decreased the release or increased the uptake by the sediments.     

Performance and Environmental Impact of Biodegradable Films in Agriculture: A Field Study on Protected Cultivation

The performance, the degradability in soil and the environmental impact of biodegradable starch-based soil mulching and low tunnel films were assessed by means of field and laboratory tests. The lifetime of the biodegradable mulches was 9 months and of the biodegradable low-tunnel films 6 months. The radiometric properties of the biodegradable films influenced positively the microclimate: air temperature under the biodegradable low tunnel films was 2 °C higher than under the low density polyethylene films, resulting in an up to 20% higher yield of strawberries. At the end of the cultivation period, the biodegradable mulches were broken up and buried in the field soil together with the plant residues. One year after burial, less than 4% of the initial weight of the biodegradable film was found in the soil. According to ecotoxicity tests, the kinetic luminescent bacteria test with Vibrio fischeri and the Enchytraeus albidus ISO/CD 16387 reproduction potential, there was no evidence of ecotoxicity in the soil during the biodegradation process. Furthermore, there was no change in the diversity of ammonia-oxidizing bacteria in the soil determined on the basis of the appearance of amoA gene diversity in denaturing gradient gel electrophoresis.