THE NEED FOR HIGH RESOLUTION TIME SERIES DATA TO CHARACTERIZE HAWAIIAN STREAMS1

ABSTRACT: Streams in the Hawaiian Islands differ from many streams on the U.S. mainland presenting unique challenges to investigators attempting to characterize Hawaiian streams. Hawaiian streams are short; watersheds are small and steep; and rain events are usually short in duration but intense. As a result, most streams in Hawai'i are flashy. Time scales for storm hydrographs in Hawai'i are on the order of hours instead of days and flash flooding is a common hazard. To characterize the streams we were investigating, we found it necessary to obtain streamflow and water quality measurements at relatively short time intervals. While this resolution resulted in large sometimes onerous quantities of data, we would have otherwise missed certain phenomena, such as 60‐fold flow changes in 15 minutes or 30‐fold turbidity changes in five minutes. Even at five‐minute intervals, we found that attempts to predict TSS using a relationship obtained from in situ turbidity were not always satisfactory. Depending on the precision required, either higher resolution measurements or in vitro turbidity measurements of the TSS samples might be necessary. Finally, these high resolution measurements enabled us to observe other cyclical events that might have been missed if the measurement intervals were greater than one hour.     

A comparison of five high-resolution spatially-explicit,fossil-fuel,carbon dioxide emission inventories for the United States

The quantification of fossil-fuel-related emissions of carbon dioxide to the atmosphere is necessary in order to accurately represent carbon cycle fluxes and to understand and project the details of the global carbon cycle. In addition, the monitoring, reporting, and verification (MRV) of carbon dioxide emissions is necessary for the success of international agreements to reduce emissions. However, existing fossil-fuel carbon dioxide (FFCO₂) emissions inventories vary in terms of the data and methods used to estimate and distribute FFCO₂. This paper compares how the approaches used to create spatially explicit FFCO₂ emissions inventories affect the spatial distribution of emissions estimates and the magnitude of emissions estimates in specific locales. Five spatially explicit FFCO₂ emission inventories were compared: Carbon Dioxide Information and Analysis Center (CDIAC), Emission Database for Global Atmospheric Research (EDGAR), Fossil Fuel Data Assimilation System (FFDAS), Open-source Data Inventory for Anthropogenic CO₂ (ODIAC), and Vulcan. The effects of using specific data and approaches in the creation of spatially explicit FFCO₂ emissions inventories, and the effect of resolution on data representation are analyzed using graphical, numerical, and cartographic approaches. We examined the effect of using top-down versus bottom-up approaches, nightlights versus population proxies, and the inclusion of large point sources. The results indicate that the approach used to distribute emissions in space creates distinct patterns in the distribution of emissions estimates and hence in the estimates of emissions in specific locations. The different datasets serve different purposes but collectively show the key role of large point sources and urban centers and the strong relationship between scale and uncertainty.     

Determination of nitrogen reduction levels necessary to reach groundwater quality targets in Slovenia

Within a collaborative project between Slovenian Environment Agency （ARSO） and Research Center Jfilich （FZJ）, nitrogen reduction levels necessary to reach groundwater quality targets in Slovenia were assessed. For this purpose the hydrological model GROWA- DENUZ was coupled with agricultural N balances and applied consistently to the whole territory of Slovenia in a spatial resolution of 100 x 100 m. GROWA was used to determine the water balance in Slovenia for the hydrologic period 1971-2000. Simultaneously, the displaceable N load in soft was assessed from agricultural Slovenian N surpluses for 2011 and the atmospheric N deposition. Subsequently, the DENUZ model was used to assess the nitrate degradation in soil and, in combination with the percolation water rates from the GROWA model, to determine nitrate concentration in the leachate. The areas showing predicted nitrate concentrations in the leachate above the EU groundwater quality standard of 50 mg NO3/L have been identified as priority areas for implementing nitrogen reduction measures. For these ＂hot spot＂ areas DENUZ was used in a backward mode to quantify the maximal permissible nitrogen surplus levels in agriculture to guarantee a nitrate concentration in percolation water below 50 mg NO3/L. Model results indicate that additional N reduction measures should be implemented in priority areas rather than area-covering. Research work will directly support the implementation of the European Union Water Framework Directive in Slovenia, e.g., by using the maximal permissible nitrogen surplus levels as a framework for the derivation of regionally adapted and hence effective nitrogen reduction measures.     

Twenty years of PET bottle to bottle recycling—An overview

Polyethylene terephthalate (PET) has become the most favourable packaging material world-wide for beverages. The reason for this development is the excellent material properties of the PET material, especially its unbreakability and the very low weight of the bottles compared to glass bottles of the same filling volume. Nowadays, PET bottles are used for softdrinks, mineral water, energy drinks, ice teas as well as for more sensitive beverages like beer, wine and juices. For a long time, however, a bottle-to-bottle recycling of post-consumer PET packaging materials was not possible, because of the lack of knowledge about contamination of packaging polymers during first use or recollection. In addition, the decontamination efficiencies of recycling processes were in most cases unknown. During the last 20 years, PET recollection as well as recycling processes made a huge progress. Today, sophisticated decontamination processes, so-called super-clean recycling processes, are available for PET, which are able to decontaminate post-consumer contaminants to concentration levels of virgin PET materials. In the 1991, the first food contact approval of post-consumer PET in direct food contact applications has been given for post-consumer recycled PET in the USA. Now, 20 years after the first food approval of a PET super-clean recycling process, this article gives an overview over the world-wide progress of the bottle-to-bottle recycling of PET beverage bottles, e.g. the recollection amount of post-consumer PET bottles and the super-clean recycling technologies.     

Stage-specific biomass overcompensation by juveniles in response to increased adult mortality in a wild fish population

Recently developed theoretical models of stage-structured consumer-resource systems have shown that stage-specific biomass overcompensation can arise in response to increased mortality rates. We parameterized a stage-structured population model to simulate the effects of increased adult mortality caused by a pathogen outbreak in the perch (Perca fluviatilis) population of Windermere (UK) in 1976. The model predicts biomass overcompensation by juveniles in response to increased adult mortality due to a shift in food-dependent growth and reproduction rates. Considering cannibalism between life stages in the model reinforces this compensatory response due to the release from predation on juveniles at high mortality rates. These model predictions are matched by our analysis of a 60-year time series of scientific monitoring of Windermere perch, which shows that the pathogen outbreak induced a strong decrease in adult biomass and a corresponding increase in juvenile biomass. Age-specific adult fecundity and size at age were higher after than before the disease outbreak, suggesting that the pathogen-induced mortality released adult perch from competition, thereby increasing somatic and reproductive growth. Higher juvenile survival after the pathogen outbreak due to a release from cannibalism likely contributed to the observed biomass overcompensation. Our findings have general implications for predicting population- and community-level responses to increased size-selective mortality caused by exploitation or disease outbreaks.