Dynamic stoichiometric response to food quality fluctuations in the heterotrophic dinoflagellate Oxyrrhis marina

With respect to nutrients, plants are rather non-homoeostatic while most metazoans have much more confined ranges of nutrient ratios. It was recently highlighted that the homoeostatic ability of microzooplankters lies in between these two extremes. Nevertheless, we know very little on the dynamics of stoichiometric changes. Hence, we investigated how the stoichiometry of the heterotrophic dinoflagellate Oxyrrhis marina is affected (1) during a starvation period and (2) when fed nutrient deplete Rhodomonas salina after having been pre-conditioned on nutrient replete algae and vice versa. We observed that the dinoflagellate was able to maintain its N:P ratio constant over 78 h of starvation. We inferred that under starvation, nitrogen-limited O. marina mainly used fat as energy source while nitrogen-rich individuals also used proteins as fuel in cellular respiration. Further, we showed that O. marina presents resistance to nutrient limitation, with stronger regulation against P-limitation than against N-limitation. This resilience in microzooplankton stoichiometry following food quality stress would have great implications for both top-down (nutrient remineralisation) and bottom-up controls (quality as food).     

Towards a coherent European approach for taxation of combustible waste

Although intra-European trade of combustible waste has grown strongly in the last decade, incineration and landfill taxes remain disparate within Europe. The paper proposes a more coherent taxation approach for Europe that is based on the principle of Pigovian taxation, i.e. the internalization of environmental damage costs. The approach aims to create a level playing field between European regions while reinforcing incentives for sustainable management of combustible waste. Three important policy recommendations emerge. First, integrating waste incineration into the European Emissions Trading System for greenhouse gases (EU ETS) reduces the risk of tax competition between regions. Second, because taxation of every single air pollutant from waste incineration is cumbersome, a differentiated waste incineration tax based on NO_x emissions can serve as a second-best instrument. Finally, in order to strengthen incentives for ash treatment, a landfill tax should apply for landfilled incineration residues. An example illustrates the coherence of the policy recommendations for incineration technologies with diverse environmental effects.     

Water quality dynamics and hydrology in nitrate loaded riparian zones in the Netherlands

Riparian zones are known to function as buffers, reducing non-point source pollution from agricultural land to streams. In the Netherlands, riparian zones are subject to high nitrogen inputs. We combined hydrological, chemical and soil profile data with groundwater modelling to evaluate whether chronically N loaded riparian zones were still mitigating diffuse nitrate fluxes. Hydraulic parameters and water quality were monitored over 2 years in 50 piezometres in a forested and grassland riparian zone. Average nitrate loadings were high in the forested zone with 87 g NO(3)(-)-N m(-2) y(-1) and significantly lower in the grassland zone with 15 g NO(3)(-)-N m(-2) y(-1). Groundwater from a second aquifer diluted the nitrate loaded agricultural runoff. Biological N removal however occurred in both riparian zones, the grassland zone removed about 63% of the incoming nitrate load, whereas in the forested zone clear symptoms of saturation were visible and only 38% of the nitrate load was removed.     

SOMPROF: A vertically explicit soil organic matter model

Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to interactions with the soil temperature and moisture profile, as well as on long (years to centuries) time scale because of depth-specific stabilization mechanisms of organic matter. It is likely that a representation of the SOM profile and surface organic layers in SOM models can improve predictions of the response of land surface fluxes to climate and environmental variability. Although models capable of simulating the vertical SOM profile exist, these were generally not developed for large scale predictive simulations and do not adequately represent surface organic horizons. We present SOMPROF, a vertically explicit SOM model, designed for implementation into large scale ecosystem and land surface models. The model dynamically simulates the vertical SOM profile and organic layer stocks based on mechanistic representations of bioturbation, liquid phase transport of organic matter, and vertical distribution of root litter input. We tested the model based on data from an old growth deciduous forest (Hainich) in Germany, and performed a sensitivity analysis of the transport parameters, and the effects of the vertical SOM distribution on temporal variation of heterotrophic respiration. Model results compare well with measured organic carbon profiles and stocks. SOMPROF is able to simulate a wide range of SOM profiles, using parameter values that are realistic compared to those found in previous studies. Results of the sensitivity analysis show that the vertical SOM distribution strongly affects temporal variation of heterotrophic respiration due to interactions with the soil temperature and moisture profile.     

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 3: alternatives to systemic insecticides

Environmental Science and Pollution Research - Over-reliance on pesticides for pest control is inflicting serious damage to the environmental services that underpin agricultural productivity. The...     

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides

Environmental Science and Pollution Research -     

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules,metabolism, fate,and transport

Environmental Science and Pollution Research - With the exponential number of published data on neonicotinoids and fipronil during the last decade, an updated review of literature has been...