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Sewage sludge application in forest plantations is an interesting complementary alternative practice to sewage sludge reutilization and recycling, with a significant and sustainable net effect in climate change mitigation. However, to optimize it a detailed knowledge of its effects on ecosystem components such as plants, soil, water and fauna is needed. We investigated the effects of sewage sludge application on soil, tree growth and floristic diversity in a ten-year-old plantation of European larch (Larix decidua Mill.). Our one-hectare study site, located at Melisey, Haute-Saone, France (47°753' Lat., 6°580' Long.), was subdivided into six plots. Three plots, alternating with three control plots (no sewage sludge application), were amended in June 2008 with 0.4tDWha-1 obtained from a municipal urban wastewater treatment plant in Melisey. Within each plot, one subplot was delimited and sludge was again manually applied at 3t of DWha-1 in July 2009 and March 2010 to the soil surface of the amended subplots without incorporation. The results showed no effect on radial and height growth of European larch amended with 0.4tDWha-1. While a significant temporary increase in pH, macro-element contents (N, P and Ca) and the trace metal (Cu and Zn) concentration in the soil was observed, it had no significant effect on needles and sporocarp contents. The number of species in the amended subplots with 3tDWha-1year-1 increased by 80% compared to the control. However, the relative species abundance present only in amended subplots remains

Wastewater plants generated annually millions of tons of sewage sludge (SS). Large amounts of this organic residue are spread on agricultural lands as a fertilizer, although it is viewed as a major potential source of contamination, presenting a danger to the terrestrial and aquatic environments. This study was undertaken to evaluate the impact of this practice on the duckweed Lemna minor and the snail Cantareus aspersus. Sludge was applied to soil either at six different loading rates equal to 0, 0.4, 3, 10, 30, and 60 tons dry matter (DM) ha(-1) for L. minor test or at three rates equal to 0, 30, and 60 tons DM ha(-1) for C. aspersus test. At the highest rate of SS application (60 tons DM ha(-1)), the eluates showed that an increase in pH (6.1) resulted in a decrease in Al levels. Thus, the high stimulation of L. minor growth observed after this high rate of SS application can be explained by (i) a reduction in Al toxicity after precipitation and (ii) macro- and micronutrient enrichment. At a rate of SS application of only 30 tons DM ha(-1), growth appeared to be slightly significant (p 0.05), in spite of the significant increase in essential mineral elements. However, it is very difficult to discriminate between Al toxicity and pH effects. For the test with C. aspersus, the snail biomass was not affected by sludge application over the exposure period. Mortality was extremely low, with a rate of less than 4 % at the last sampling date. Yet, Cu, Pb, and Cd accumulated significantly in the soft body of snails exposed to SS application, suggesting that the amount of metals excreted is lower than that absorbed. In contrast, Zn levels remain constant, inferring that absorption and elimination of Zn are balanced at the beginning of the experiment.

Algal proliferation has commonly been reported to occur on monuments, such as crypts, churches, and caves, as soon as artificial lighting is used. In this work we study the effects of UV–C irradiation on algae collected in different caves in Dordogne (southwest of France). First, the effect of UV–C irradiation was tested on algal cell suspensions during increasing exposure times. After treatment, the photosynthetic capacity was assayed using a polarometric method, and algal cell viability was then estimated using a Trypan blue test after a rest period of 15 h. UV–C irradiation was then studied on algal cells cultivated on a solid support consisting of pieces of calcareous stone. Drops of concentrated algal cells were inoculated on stone and exposed to UV–C radiation for 3, 6, or 9 h. After this irradiation, half of the samples were submitted to a high white light intensity (1400 μmol m−2 s−1 of photosynthetically active radiation, PAR) for 6 h while the other half were incubated in the culture room. Subsequently, algal macroscopic parameters such as covering rate and colonized area were measured by macro photography. Both experiments led to the conclusion that UV–C irradiation has deleterious effects on photosynthetic parameters and growth of algal cells.

In the conservation field of buildings, historical monuments and subterranean environments, very few studies highlight the importance to find alternative methods to chemical products against algal biofilm proliferation. Indeed, biofouling by microorganisms is a well-known biodeterioration phenomenon. Algae are considered as pioneers in the biodeterioration of stone, and that's why they are subject to a special interest in this chapter. Conservators of monuments or art works used many chemical applications to prevent or to control the algal proliferation on stone. But, due to the changes in European standards on their use, the chemical products must be replaced by environmentally friendly processes. The ultraviolet irradiation appeared to be a suitable process to control algal proliferation in these environments. Firstly in this chapter, we describe the problematic of algal biofilms (proliferation and biodeterioration) on different substrata and also the effects of applied chemical treatments. Secondly, we define and characterize the UV light and its effects on living organisms. Finally, we present the experimental design and the obtained results on algae harvested in caves at the cellular and molecular scales (pigment contents, photosynthetic activity, DNA damages...) and at the biofilm scale (proliferation measurements). This study shows that the UV treatment can be used as a conservation tool to eradicate algal biofilms which proliferate in buildings and monuments.