Effects of sensitizers on the photodegradation of the systemic fungicide triadimenol

The photochemical behaviour of triadimenol (1) under various conditions has been examined. Significant degradation is obtained only in the presence of electron-acceptor sensitizers as 9,10-dicyanoanthracene or 2,4,6-triphenylpyrylium tetrafluoroborate, and long irradiation times are required. 1H-1,2,4-Triazole (2), 4-chlorophenyl formate (3), 4-chlorophenol (4), 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1H-1,2,4-triazol-1-yl)butan-2-one (5), 4-chlorophenyl 2,2-dimethylpropanoate (6) and 4-chlorobenzoic acid (7) were identified as photoproducts by NMR and GC-MS.     

The impact of municipal solid waste management on greenhouse gas emissions in the United States

Technological advancements, environmental regulations, and emphasis on resource conservation and recovery have greatly reduced the environmental impacts of municipal solid waste (MSW) management, including emissions of greenhouse gases (GHGs). This study was conducted using a life-cycle methodology to track changes in GHG emissions during the past 25 years from the management of MSW in the United States. For the baseline year of 1974, MSW management consisted of limited recycling, combustion without energy recovery, and landfilling without gas collection or control. This was compared with data for 1980, 1990, and 1997, accounting for changes in MSW quantity, composition, management practices, and technology. Over time, the United States has moved toward increased recycling, composting, combustion (with energy recovery) and landfilling with gas recovery, control, and utilization. These changes were accounted for with historical data on MSW composition, quantities, management practices, and technological changes. Included in the analysis were the benefits of materials recycling and energy recovery to the extent that these displace virgin raw materials and fossil fuel electricity production, respectively. Carbon sinks associated with MSW management also were addressed. The results indicate that the MSW management actions taken by U.S. communities have significantly reduced potential GHG emissions despite an almost 2-fold increase in waste generation. GHG emissions from MSW management were estimated to be 36 million metric tons carbon equivalents (MMTCE) in 1974 and 8 MMTCE in 1997. If MSW were being managed today as it was in 1974, GHG emissions would be approximately 60 MMTCE.     

Stability of eelgrass (<Emphasis Type="Italic">Zostera marina</Emphasis> L.) depth limits: influence of habitat type

Seagrass meadows are generally considered stable although few studies have specified and tested this statement. On the basis of a large monitoring dataset from Danish coastal waters, we aimed to test whether the stability of deep eelgrass populations changes along a eutrophication gradient extending from inner bays over outer bays to open coastal waters. We defined stability in terms of the stability properties of constancy, resilience, and/or persistence. Our data allowed us to investigate the stability property constancy expressed as temporal variability in eelgrass depth limits over a time scale of 10 years. We hypothesised that colonisation depths were large and relatively constant along open coasts because of low and relatively constant levels of nutrients and turbidity. Conversely, colonisation depths were hypothesised to be low and variable in protected bays due to higher and more variable levels of nutrients and turbidity. We found that depth limits increased from inner bays towards open coastal waters, matching declines in nutrient concentration and increases in water clarity and oxygen concentration. Stability expressed as constancy of depth limits did not differ significantly between habitat types, and neither did stability of physicochemical variables. However, when data from all habitat types were analysed together, they showed that eelgrass populations at the depth limit were significantly more constant and thus, in this respect, more stable when occurring in deep waters as compared to shallow waters. Areas of good water quality may thus obtain the double benefit of deeper-growing and more stable eelgrass populations. The most likely reason why this pattern did not appear at habitat-type level is that the habitat types studied represented wide spatial variation in water quality and depth limit. We conclude that the question of whether eelgrass populations are stable depends on the stability property and the ecological situation in question. Populations may be considered unstable in terms of inter-annual variation but stable in terms of long-term persistence. Therefore, the common statement that eelgrass populations are stable is not universally true.Communicated by M. Kühl, Helsingør     

Trophic relationships in the recently impounded Bagré reservoir in Burkina Faso

The trophic dynamics of Bagré reservoir which has been recently impounded in Burkina Faso was based on the data collected during 1997–1998 period using the Ecopath model and software. Total fish biomass is 22.63 t km⁻² and mainly represents trophic levels (TLs) 2 and 3. The trophic food chain is relatively long and the overall transfer efficiency is quite low. Grazing foodweb based on primary producers is prominent in the reservoir ecosystem and detritus plays a less significant role. Seasonal and long-term variations in water quality have significant influences on the lower TLs clearly showing a bottom-up functioning of the ecosystem. Environmental degradations, such as siltation occurring in the lake, suggest possible risks in limiting ecosystem productivity.     

A study on the landfill leachate and its impact on the groundwater quality of the greater area

Characterisation of the leachate originating from the Ano Liosia landfill (situated in Attica region, Greece) as well as assessment on the quality of the local aquifer were carried out. The experimental results showed that most of the parameters examined in the leachate samples such as colour, conductivity, TS, COD, NH₃–N, PO₄–P, SO₄ ^2–, Cl^–, K⁺, Fe and Pb were found in high levels. The organic load was quite high since the COD concentrations were in the range of 3250–6125mgL^–1. In addition, the low BOD/COD ratio (0.096–0.195), confirmed that the majority of this organic matter is not easily biodegradable. The groundwater near the landfill site was characterised as not potable and not suitable for irrigation water, since most of the physical and chemical parameters examined – such as colour, conductivity, DS, hardness, Cl^–, NH₃–N, COD, K⁺, Na⁺, Ca²⁺, Fe, Ni and Pb exceeded the permissible limits given by EE, EPA and the Greek Ministry of Agriculture. Furthermore, this study presents the application of the hydrologic evaluation of landfill performance (HELP) model for the determination of the yearly leakage from the base of the landfill after the final capping.     

Effects of prenatal yolk androgens on armaments and ornaments of the ring-necked pheasant

Mothers may profoundly affect offspring phenotype and performance by adjusting egg components, including steroid hormones. We studied the effects of elevated prenatal testosterone (T) exposure in the ring-necked pheasant on the expression of a suite of male and female traits, including perinatal response to stress, immune response, growth, and secondary sexual traits. Prenatal T levels were increased by injecting the yolk of unincubated eggs with physiological doses of the hormone. Yolk T injection resulted in a reduced length of male tarsal spurs, a trait which positively predicts male success in intra- and intersexual selection and viability, whereas no direct effect on male wattle characteristics or plumage traits of either sex was observed. Female spur length was also negatively affected by T, but to a lesser extent than in males. In addition, the covariation between male secondary sexual traits, which are reliable quality indicators, differed between T and control males, suggesting that the manipulation may have altered the assessment of overall male quality by other males and females. In conclusion, the negative effects of elevated yolk T on spur length, a trait which positively predicts male fitness, coupled with the lack of effects on growth or other traits in both sexes, provided limited evidence for mothers being subjected to a trade-off between positive and negative consequences of yolk T deposition on offspring traits and suggest that directional selection for reduced yolk T levels may occur in the ring-necked pheasant.     

The value of small size: loss of forest patches and ecological thresholds in southern Madagascar.

Many services generated by forest ecosystems provide essential support for human well-being. However, the vulnerability of these services to environmental change such as forest fragmentation are still poorly understood. We present spatial modeling of the generation of ecosystem services in a human-dominated landscape where forest habitat patches, protected by local taboos, are located in a matrix of cultivated land in southern Madagascar. Two ecosystem services dependent on the forest habitats were addressed: (1) crop pollination services by wild and semidomesticated bees (Apoidea), essential for local crop production of, for example, beans, and (2) seed dispersal services based on the presence of ring-tailed lemurs (Lemur catta). We studied the vulnerability of these ecosystem services to a plausible scenario of successive destruction of the smallest habitat patches. Our results indicate that, in spite of the fragmented nature of the landscape, the fraction of the landscape presently covered by both crop pollination and seed dispersal services is surprisingly high. It seems that the taboo system, though indirectly and unintentionally, contributes to upholding the generation of these services by protecting the forest patches. Both services are, however, predicted to be very vulnerable to the successive removal of small patches. For crop pollination, the rate of decrease in cover was significant even when only the smallest habitat patches were removed. The capacity for seed dispersal across the landscape displayed several thresholds with habitat patch removal. Our results suggest that, in order to maintain capacity for seed dispersal across the landscape and crop pollination cover in southern Androy, the geographical location of the remaining forest patches is more crucial than their size. We argue that in heavily fragmented production landscapes, small forest patches should increasingly be viewed as essential for maintaining ecosystem services, such as agricultural production, and also should be considered in the ongoing process of tripling the area of protected habitats in Madagascar.     

Characterization of dissolved organic matter from saline soils by fluorescence spectroscopy

In this paper hydrophilic (HI) and hydrophobic (HO) fractions of dissolved organic matter (DOM) extracted from soils at different degrees of salinisation were characterised by means of fluorescence spectroscopy in the emission, excitation and synchronous-scan modes. Results provided evidence of the different chemical nature of DOM fractions and allowed to distinguish hydrophilic and hydrophobic fractions extracted from the same soil substrate. The strong decrease in fluorescence intensity observed with the increasing salinity of the soils can be utilised to obtain information on the salinity level of different soil substrates by comparison of spectral fluorescence intensities.