Phenological match drives pollen-mediated gene flow in a temporally dimorphic tree.

Variation in flowering phenology is common in natural populations, and is expected to be, together with inter-mate distance, an important driver of effective pollen dispersal. In populations composed of plants with temporally separated sexual phases (i.e. dichogamous or heterodichogamous populations), pollen-mediated gene flow is assumed to reflect phenological overlap between complementary sexual phases. In this study, we conducted paternity analyses to test this hypothesis in the temporally dimorphic tree Acer opalus. We performed spatially explicit analyses based on categorical and fractional paternity assignment, and included tree size, pair-wise genetic relatedness and morph type as additional predictors. Because differences between morphs in flowering phenology may also influence pollination distances, we modelled separate pollen dispersal kernels for the two morphs. Extended phenological overlap between male and female phases (mainly associated with inter-morph crosses) resulted in higher siring success after accounting for the effects of genetic relatedness, morph type and tree size, while reduced phenological overlap (mainly associated with intra-morph crosses) resulted in longer pollination distances achieved. Siring success also increased in larger trees. Mating patterns could not be predicted by phenology alone. However, as heterogeneity in flowering phenology was the single morph-specific predictor of siring success, it is expected to be key in maintaining the temporal dimorphism in A. opalus, by promoting not only a prevalent pattern of inter-morph mating, but also long-distance pollination resulting from intra-morph mating events.

Treatment of the azo dye direct blue 2 in a biological aerated filter under anaerobic/aerobic conditions.

The main objective of this research was to determine the feasibility to treat the azo dye direct blue 2 together with municipal wastewater in a biological aerated filter (BAF) using lava stones as support of the microorganisms and under combined anaerobic/aerobic conditions. A 3 m high pilot biological aerated filter was fed with municipal wastewater and, after several weeks, the azo dye direct blue 2 was added to the wastewater to reach a final concentration of 50 mg/L (34 mgCOD/L). Under continuous operation, two strategies were tested: Alternating aeration (12 h anaerobic and 12 h aerobic) and combined aeration (the lower part of the filter anaerobic and the upper part aerobic). The results indicate that municipal wastewater acted as a good electron donor resulting in satisfactory COD and dye removal rates. Better dye removal (61%) was obtained with combined aeration than with alternating aeration (45%). After beginning the azo dye addition, the COD removal rates decreased from 87 to 81% for both alternating and combined aeration procedures. The average ammonia nitrogen removal, without the addition of the dye, was 73% and increased to 90% shortly after beginning the dye addition, then it decreased to 81% during the combined aeration period. Excellent nitrification was observed in the upper aerobic part of the filter. For the combined aeration phase, the conditions change from anaerobic to aerobic does not seem to affect the behavior of the COD and TSS curves.

Two combined techniques to enhance anaerobic digestion of sludge.

The rate-limiting step during anaerobic digestion is the hydrolysis of the particulate organic matter and methanogenesis. Certain elements, such as iron, nickel and cobalt and some growth factors such as coenzymes are needed for the adequate growth of the organisms. The main objective of this research was to enhance anaerobic digestion of primary sludge combining thermal and alkaline pre-treatment with stimulation of the methanogenic activity by adding yeast extract. Primary sludge was exposed, separately, to alkaline and thermal pre-treatment procedures. After this pre-treatment, different amounts of yeast extract were added to the sludge. The best COD, TSS and VSS removal rates were observed without pre-treatment and with the addition of 0.1% in weight of yeast extract. The highest specific methane production was obtained with thermal pre-treatment and 0.1% yeast addition. A second experimental stage was run for a closer analysis of the preliminary results. Thermal pre-treatment and 0.1% yeast addition was tested. The best results regarding both COD, TSS and VSS removal rates and methane production were obtained without thermal pre-treatment and with addition of yeast extract. The calculated F-values for the ANOVA-test show that the main influencing factor was the addition of yeast extract where the Biochemical Methane Production was doubled compared with the blank. The highest values for the hydrolysis constants were obtained at hydraulic retention times of six days after adding 0.1% of yeast extract.