Effects of Sewage Sludge on Plant Community Composition in Restored Limestone Quarries

The effects of sewage sludge, used to improve fertility of replaced soil, on vegetation were studied in limestone quarry restoration. Plant community growing in the first stages after sludge application was surveyed in six quarries of NE Spain. Areas with a mixture of sewage sludge and residual soil were compared to areas where the application consisted only of residual soil (a mixture of previous top soil and mine spoils). Sewage sludge was hypothesized to increase total biomass and cover, modifying species composition and delaying the early successional recover of the community. The results showed that both biomass and plant cover increased because of sewage sludge addition. The floristic composition was dominated by ruderal species that did not show any dependence on sewage sludge application. Convergence on similarity between sludge and control plots was not detected along a 5‐year period. Although species richness was significantly lower in sludge plots, diversity and equitability indexes did not show differences between treatments. The results did not show differences in the proportion of non‐native species. The proportion of legumes was lower in sludge plots. These results show that the plant communities resulting from the addition of sewage sludge to the soil used in limestone quarry restoration have more biomass and cover, but less number of species, and they do not show a clear trend to converge to those areas restored only with non‐amended soil.     

A yield control approach to assess phytoavailability of Zn and Cu in irradiated,composted sewage sludges and composted manure in field experiments: II. Copper

Organic wastes such as sewage sludges contain copper (Cu). Increased attention to environmental protection requires that wastes be treated with pathogen-eliminating procedures before application to farmland. It is not clear, however, if such procedures affect the plant availability of Cu in the wastes. This 2-year field research investigated the effect of irradiation and composting on Cu availability in sludges and manure using a yield control approach. Four organic wastes [digested and dewatered (DSS), digested and irradiated (DISS), composted (DICSS) sewage sludges and composted livestock manure (CLM)] were applied at four rates (10, 20, 30 and 40 t solid ha^–1 year^–1) with supplemented N and K fertilizers. A control treatment (CT) received N and K fertilizers only. Beans, lettuce and petunias were grown in first year and lettuce were harvested twice in second year. Beans appeared to have a strong ability to absorb Cu compared with the other test crops. In general, crop Cu concentration responses to Cu applied in DSS and DISS were well described by quadratic equations. Tested by a paired t-test, Cu concentration in bean pods was higher in DISS than in DSS treatment, indicating that irradiation increased phytoavailability of Cu. However, the parabolic response of crop Cu to Cu applied in DISS, suggesting that the increases were confined to the lower rates of DISS. Copper applied in DICSS did not increase Cu concentration in any of the test crops. At a given level of applied Cu, crop Cu tended to be lower in DICSS than in DSS or DISS treatment. Sludge composting depressed phytoavailability of Cu. Copper concentration in CLM was much lower than in sludges and sludge composts, but application of CLM increased Cu concentration in bean pods. The pattens of Cu concentration in the two cuts of lettuce in 1991 to Cu applied in CLM were similar, where low rates of CLM application slightly reduced Cu concentration, then the Cu concentration increased with increased rates. The dynamics of available Cu supply were different in the sludge composts and manure composts.     

Impact of sewage pollution on two species of sea urchins in the Mediterranean Sea (Cortiou,France): Radial asymmetry as a bioindicator of stress

BackgroundThe surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.MethodsWe used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs and primary tubercles.ResultsFor both species, the most polluted sampling site, Cortiou, displayed the highest level of FA, while the Maire and East Maire sampling sites displayed the lowest levels. A. lixula revealed systematic differences in FA among sampling sites for all characters and P. lividus showed differences in FA for the number of primary tubercles.ConclusionsStatistical analyses of FA show a concordance between the spatial patterns of FA among sampling sites and the spatial distribution of sewage discharge pollutants in the Cortiou area. High developmental stress in these sampling sites is associated with exposure to high concentrations of heavy metals and many harmful organic substances contained in wastewater. FA estimated from structures with complex symmetry appears to be a fast and reliable tool to detect subtle differences in FA. Its use in biomonitoring programs for inferring anthropogenic and natural environmental stress is suggested.     

GRACILARIA EDULIS (RHODOPHYTA) AS A BIOLOGICAL INDICATOR OF PULSED NUTRIENTS IN OLIGOTROPHIC WATERS

The response of the marine macroalga Gracilaria edulis (Gmelin) Silva to nutrient pulses of varying magnitude was investigated to test its applicability as a marine bioindicator at two oligotrophic locations. After exposure to nutrient pulses, algal amino acid, tissue nitrogen, and chlorophyll a content were assessed relative to algae incubated under control conditions (no nutrient enrichment). The smallest nutrient pulse involved a nutrient enrichment experiment conducted within a coral atoll, whereas two larger pulses resulted from sewage discharge to a tropical coastal bay. After exposure to the smallest nutrient pulse (10 × ambient), only changes in macroalgal amino acid concentration and composition were detected (mainly as increases in citrulline). At 100 × ambient concentrations, increases in tissue % nitrogen of the macroalgae were detected, in addition to responses in amino acids. Macroalgae exposed to the highest nutrient pulse (1000 × ambient) responded with increased chlorophyll a , tissue nitrogen, and amino acids within the three day incubation period. In contrast to these algal responses, analytical water sampling techniques failed to detect elevated nutrients when nutrient pulses were not occurring. The responses of this algal bioindicator to variable nutrient pulses may provide a useful tool for investigating the source and geographical extent of nutrients entering oligotrophic coastal waters.     

Ground beetle communities on reclaimed mine spoil: Effects of organic matter application and revegetation

On a study site in the Lusatian lignite mining region (Germany), sandy mine spoil was ameliorated with either sewage sludge, compost or mineral fertilizer. Plots were sown with the grass Secale multicaule and planted with pine seedlings except for a control that was not meliorated and not revegetated. Pitfall catches of ground beetles in 1996/97 yielded high numbers of species and individuals directly after revegetation. The dominant beetles were xerophilic species, known to prefer open sandy sites. Catches in different plots were positively correlated with the amount of vegetation cover and declined as follows: amelioration with sewage sludge > compost > mineral fertilizer > untreated control. Even beetles characteristic of open sandy sites showed a distinct preference for plots with high vegetation cover treated with organic waste. For the dominant species, an attraction to shelter and a more balanced, humid microclimate is assumed. A year-to-year comparison showed an increase in beetles typical of dry grasslands and ruderal sites in the second year, while characteristic species of open sandy sites decreased. Application of organic waste combined with revegetation led to an immediate increase in beetle numbers. In the long term, revegetation would be expected to reduce suitable habitats for endangered ground beetles which prefer open sites with poor sandy soils. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.     

藻菌共生处理污水的机制与应用研究进展

在污水处理领域,藻菌共生有同步脱氮、除磷效率高、排放温室气体量低、生物质可资源化回收等优势,近年来受到学者的重视.目前鲜有综述污水处理中藻类与细菌、真菌及混合藻菌间互作机制的文章.本文从藻类-细菌、藻类-真菌、混合藻-混合菌3个方面介绍藻菌共生处理污水的研究进展,重点阐述藻菌间营养物质交换、信号传导及生物絮凝3种不同互...     

Bacterial pathogens in wild birds: a review of the frequency and effects of infection

The importance of wild birds as potential vectors of disease has received recent renewed empirical interest, especially regarding human health. Understanding the spread of bacterial pathogens in wild birds may serve as a useful model for examining the spread of other disease organisms, both amongst birds, and from birds to other taxa. Information regarding the normal gastrointestinal bacterial flora is limited for the majority of wild bird species, with the few well-studied examples concentrating on bacteria that are zoonotic and/or relate to avian species of commercial interest. However, most studies are limited by small sample sizes, the frequent absence of longitudinal data, and the constraints of using selective techniques to isolate specific pathogens. The pathogenic genera found in the gut are often those suspected to exist in the birds' habitat, and although correlations are made between bacterial pathogens in the avian gut and those found in their foraging grounds, little is known about the effect of the pathogen on the host, unless the causative organism is lethal. In this review, we provide an overview of the main bacterial pathogens isolated from birds (with particular emphasis on enteropathogenic bacteria) which have the potential to cause disease in both birds and humans, whilst drawing attention to the limitations of traditional detection methods and possible study biases. We consider factors likely to affect the susceptibility of birds to bacterial pathogens, including environmental exposure and heterogeneities within the host population, and present probable avenues of disease transmission amongst birds and from birds to other animal taxa. Our primary aim is to identify gaps in current knowledge and to propose areas for future study.     

The Effects of Bacterial Leaching on Metal Partitioning in Sewage Sludge

The partitioning of Mn, Al, Zn, Cu and Ti ions in municipal sewage sludge was investigated before and after bioleaching processes effectuated by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Oxidation–reduction potential increase and pH decrease were obtained as a result of bacterial activity. A less pronounced and constant decrease was obtained with A. ferrooxidans, whereas A. thiooxidans presented a lag phase before a steep pH decrease. Metal solubilization was accomplished in experimental systems supplemented with energy source, Fe²⁺ for A. ferrooxidans and S⁰ for A. thiooxidans. Solubilization efficiency differed for each metal except for Al, and was relatively similar for either organism. Metal partitioning was conducted using a five-step sequential extraction procedure before and after the bioleaching. The results indicated that Zn and Mn ions were mostly associated with the organic fraction, whereas Cu, Al and Ti ions with the sulphide/residue fraction. The bioleaching process caused prompt solubilization of metals mostly associated with the more labile fractions (exchangeable, adsorbed and organically bound metals), whereas those associated to the less labile ones (EDTA and sulphide/residue fractions) were exchanged towards more labile fractions.