Different reduced sulfur compounds (H2S, FeS, S2O32−) were tested as electron donors for dissimilatory nitrate reduction in nitrate‐amended sediment slurries. Only in the free sulfide‐enriched slurries was nitrate appreciably reduced to ammonia (), with concomitant oxidation of sulfide to S0 (). The initial concentration of free sulfide appears as a factor determining the type of nitrate reduction. At extremely low concentrations of free S2− (metal sulfides) nitrate was reduced via denitrification whereas at higher S2− concentrations, dissimilatory nitrate reduction to ammonia (DNRA) and incomplete denitrification to gaseous nitrogen oxides took place. Sulfide inhibition of NO‐ and N2O‐ reductases is proposed as being responsible for the driving part of the electron flow from S2− to NH4+.

Different reduced sulfur compounds (H ., S, FeS, S,O:-> were tested as electron donors for dissimilatory nitrate reduction in nitrate-amended sediment slurries. Only-in the free sulfide-enriched slurries was nitrate appreciably reduced to ammonia (0.30 pmol NHl/ymol NO;), with concomitant oxidation of sulfide to So (0.55 pmol S'/pmol S*-). The initial concentration of free sulfide appears as a factor determining the type of nitrate reduction. At extremely low concentrations of free S'-(metal sulfides) nitrate was reduced via denitrification whereas at higher S*-concentrations, dissimilatory nitrate reduction to ammonia (DNRA) and incomplete denitrification to gaseous nitrogen oxides took place. Sulfide inhibition of NO-and N,O-reductases is proposed as being responsible for the driving part of the electron flow from S'-to NH:.

No abstract

This study analyses the water temperature changes in Lake Banyoles over the past four decades. Lake Banyoles, Spain’s second highest lake, situated in the western Mediterranean (NE Iberian Peninsula). Over the past 44 years, the warming trend of the lake’s surface waters (0.52 °C decade−1) and the cooling trend of its deep waters (−0.66 °C decade−1) during summer (July–September) have resulted in an increased degree of stratification. Furthermore, the stratification period is currently double that of the 1970s. Meanwhile, over the past two decades, lake surface turbidity has remained constant in summer. Although turbidity did decrease during winter, it still remained higher than in the summer months. This reduction in turbidity is likely associated with the decrease in groundwater input into the lake, which has been caused by a significant decrease in rainfall in the aquifer recharge area that feeds the lake through groundwater sources. As a unique freshwater sentinel lake under the influence of the climate change, Lake Banyoles provides evidence that global warming in the western Mediterranean boosts the strength and duration of the lake’s stratification and, in response, the associated decrease in the turbidity of its epilimnion.

No abstract