Performance evaluation of phycocyanin probes for the monitoring of cyanobacteria

The performance of two field probes (YSI 6600 and TriOS), used for the measurement of in vivo phycocyanin fluorescence, was compared and validated in the laboratory in 2008 and 2009 with cultures of Microcystis aeruginosa and field samples. The background noise of the two probes was low and the detection limits were estimated at 1500 cells mL(-1) for the YSI and 0.69 μg PC L(-1) for the TriOS. The linearity and repeatability of both probes have been excellent. Strong relationships were observed between the in vivo fluorescence and the total cyanobacterial biovolume (R(2) = 0.82 YSI; 0.83 TriOS) or the abundance (R(2) = 0.71 YSI; 0.75 TriOS) of cyanobacteria. However, the difference between cell densities determined by microscopy and measured by the YSI can be very large and has been associated to the variability of cell volume among cyanobacteria. This last observation makes the YSI a qualitative tool if a post-calibration is not done. The analysis of filtrated samples showed that dissolved phycocyanin (extracellular) may represent a significant fluorescence signal. No relationship could be established between the abundance, the total cyanobacterial biovolume or the in vivo fluorescence of phycocyanin and the concentrations of cyanotoxins (R(2) ≤ 0.22).     

Modeling eelgrass spatial response to nutrient abatement measures in a changing climate

For many coastal areas including the Baltic Sea, ambitious nutrient abatement goals have been set to curb eutrophication, but benefits of such measures were normally not studied in light of anticipated climate change. To project the likely responses of nutrient abatement on eelgrass (Zostera marina), we coupled a species distribution model with a biogeochemical model, obtaining future water turbidity, and a wave model for predicting the future hydrodynamics in the coastal area. Using this, eelgrass distribution was modeled for different combinations of nutrient scenarios and future wind fields. We are the first to demonstrate that while under a business as usual scenario overall eelgrass area will not recover, nutrient reductions that fulfill the Helsinki Commission’s Baltic Sea Action Plan (BSAP) are likely to lead to a substantial areal expansion of eelgrass coverage, primarily at the current distribution’s lower depth limits, thereby overcompensating losses in shallow areas caused by a stormier climate.     

Contrasting influence of soil nutrients and microbial community on differently sized basal consumers

There is increasing evidence of the coexistence of trophic and environmental constraints belowground. While too often ignored in current literature, the extent to which phosphorus is relevant for soil biota was demonstrated in this study by positive correlations of soil C/P and N/P ratios with all the measured microbial parameters (biomass, density and activity), with the numerical abundance of roundworms (Nematoda) and potworms (Enchytraeidae) from lower trophic levels and with the roundworm biomass. Total worm biomass seems dependent on land use, being in rangelands about twice as high as in croplands, although the relative contribution of potworms remains comparable for both land use types (49?±?20 % SD versus 45?±?27 % SD). Besides soil [P], soil type plays an important role in the relative biomass of potworms compared to roundworms. Soil parameters (here pH, C/P and N/P ratios) are better predictors for the abundance and biomass of roundworms than microbial parameters. We also propose a graphical way to visualize the major responses of basal consumers to their microbial drivers.     

Veränderung von Biokonzentration und Wirkung vom PSM in Anwesenheit von Huminstoffen

Humic substances, in aqueous bodies primarily fulvic acids, may demonstrate an inhibitory as well as an activating influence on organisms. We present evidence with bacteria-containing algal cultures and with cultures of the nematodeCaenorhabditis elegans. Structural elements of the fulvic acids which may be responsible for such effects are not yet known. Furthermore, the presence of fulvic acids may lead to increases in bioconcentration of xenobiotics. Increase in the toxicity of xenobiotics in the presence of humic substances have also been described. We present studies applying lethal as well as sublethal toxicity endpoints.     

Atmospheric photochemistry and secondary aerosol formation of urban air in Lyon, France

Photochemical aging of volatile organic compounds (VOCs) in the atmosphere is an important source of secondary organic aerosol (SOA). To evaluate the formation potential of SOA at an urban site in Lyon (France), an outdoor experiment using a Potential Aerosol Mass (PAM) oxidation flow reactor (OFR) was conducted throughout entire days during January-February 2017. Diurnal variation of SOA formations and their correlation with OH radical exposure (OHexp), ambient pollutants (VOCs and particulate matters, PM), Relative Humidity (RH), and temperature were explored in this study. Ambient urban air was exposed to high concentration of OH radicals with OHexp in range of (0.2–1.2)×10¹² molecule/(cm³?sec), corresponding to several days to weeks of equivalent atmospheric photochemical aging. The results informed that urban air at Lyon has high potency to contribute to SOA, and these SOA productions were favored from OH radical photochemical oxidation rather than via ozonolysis. Maximum SOA formation (36 µg/m³) was obtained at OHexp of about 7.4 × 10¹¹molecule/(cm³?sec), equivalent to approximately 5 days of atmospheric oxidation. The correlation between SOA formation and ambient environment conditions (RH & temperature, VOCs and PM) was observed. It was the first time to estimate SOA formation potential from ambient air over a long period in urban environment of Lyon.     

Measurement of heterogeneous uptake of NO2 on inorganic particles, sea water and urban grime

Heterogeneous reactions of NO₂ on different surfaces play an important role in atmospheric NO_x removal and HONO formation, having profound impacts on photochemistry in polluted urban areas. Previous studies have suggested that the NO₂ uptake on the ground or aerosol surfaces could be a dominant source for elevated HONO during the daytime. However, the uptake behavior of NO₂ varies with different surfaces, and different uptake coefficients were used or derived in different studies. To obtain a more holistic picture of heterogeneous NO₂ uptake on different surfaces, a series of laboratory experiments using different flow tube reactors was conducted, and the NO₂ uptake coefficients (γ) were determined on inorganic particles, sea water and urban grime. The results showed that heterogeneous reactions on those surfaces were generally weak in dark conditions, with the measured γ varied from <10^?8 to 3.2 × 10^?7 under different humidity. A photo-enhanced uptake of NO₂ on urban grime was observed, with the obvious formation of HONO and NO from the heterogeneous reaction. The photo-enhanced γ was measured to be 1.9 × 10^?6 at 5% relative humidity (RH) and 5.8 × 10^?6 at 70% RH on urban grime, showing a positive RH dependence for both NO₂ uptake and HONO formation. The results demonstrate an important role of urban grime in the daytime NO₂-to-HONO conversion, and could be helpful to explain the unknown daytime HONO source in the polluted urban area.     

Overview of the Brazilian Citriculture Certification

This study aims to characterize the different types of certification in the Brazilian citriculture as well as analyze the major changes in the market. The paper also has the objective to discuss how social and environmental factors influence the demand for food certifications and the sustainability and ethics aspects in the field. Therefore, a literature review on the subject was carried out as well as a qualitative research using interviews with certifiers, governmental institutions, farmers, cooperatives and producer associations. The certification is becoming mandatory for those working in foreign markets and for those working nationally; it can be a competitive differential. The organic certification in citriculture shows the highest number of growers. Companies with large areas of citrus and the orange juice processing industry are adhering to this certification in order to maintain themselves competitive in the market. There is an enormous potential of Brazilian citriculture certification, because the certified area is still less than 6 % of the total area. Certification reduces the asymmetry of information and consists of an important step towards sustainability although incapable of solely guaranteeing it.     

Heat warnings and avoidance behavior: evidence from a bike-sharing system

Environmental Economics and Policy Studies - Governments throughout the globe usually implement early warning systems to prevent health-related costs from exposure to extreme heat. In a warming...     

Sea-level rise in Indonesia: on adaptation priorities in the agricultural sector

Adaptation to climate-change impacts requires understanding of where impacts are to be expected and what their magnitude may be. Adaptation funds are only a limited resource for helping affected parties in coping with climate-change impacts. The application of suitable methods helps to determine the recipients of adaptation aid. A quantification of impacts based on different impact analyses can aid in taking on various perspectives on the same problem in order to identify the appropriate perspective for the given decision-making context or for identifying impact patterns. Once executed, this prioritizes adaptation needs and finding a suitable allocation rule, given the policy makers perception of the decision-making context. The study introduces a set of methods of spatially explicit, sub-national (province level), and country-wide impact analyses regarding inundation impacts on agricultural areas for four important food crops in Indonesia. These methods are applied to a 1 and 2 m sea-level rise scenario and include a novel approach for impact analyses, data envelopment analysis, which is not widely used in environmental studies as of yet. Based on the given case study, the paper demonstrates the applicability of these methods and identifies impact patterns.