Drainage Effects on Stream Nitrate-N and Hydrology in South-Central Minnesota (USA)

Excessive nitrate-N in south-central Minnesota ditches and streams is related to land-use change, and may be contributing to the development of the zone of hypoxia in the Gulf of Mexico. Intensive land-use (agricultural management) has progressively increased as subsurface drainage has improved crop productivity over the past 25 years. We have examined water at varying scales for delta18O and, nitrate-N concentrations. Additionally, analysis of annual peak flows, and channel geomorphic features provided a measure of hydrologic change. Laboratory and field results indicate that agricultural drainage has influenced riverine source waters, concentrations of nitrate-N, channel dimensions and hydrology in the Blue Earth River (BER) Basin. At the mouth of the BER shallow ground water comprises the largest source water component. The highest nitrate-N concentrations in the BER and tributaries typically occurred in May and June and ranged from 7-34 mg L(-1). Peak flows for the 1.01-2-yr recurrence intervals increased by 20-to-206% over the past 25 years. Geomorphic data suggest that small channels (ditches) were entrenched by design, whereas, natural that are disconnected from an accessible riparian corridor. Frequent access to a functioning riparian zone is important for denitrification.     

Geological CO2 Storage as a Climate Change Mitigation Option

Carbon dioxide (CO₂₎ capture and storage is increasingly being considered as an important climate change mitigation option. This paper explores provisions for including geological CO₂ storage in climate policy. The storage capacity of Norway's Continental Shelf is alone sufficient to store a large share of European CO₂ emissions for many decades. If CO₂ is injected into oil reservoirs there is an additional benefit in terms of enhanced oil recovery. However, there are significant technical and economic challenges, including the large investment in infrastructure required, with related economies of scale properties. Thus CO₂ capture, transportation and storage projects are likely to be more economically attractive if developed on a large scale, which could mean involving two or more nations. An additional challenge is the risk of future leakages from storage sites, where the government must take on a major responsibility. In institutional and policy terms, important challenges are the unsettled status of geological CO₂ storage as a policy measure in the Kyoto Protocol, lack of relevant reporting and verification procedures, and lack of decisions on how the option should be linked to the flexibility mechanisms under the Kyoto Protocol. In terms of competitiveness with expected prices for CO₂ permits under Kyoto Protocol trading, the relatively high costs per tonne of CO₂ stored means that geological CO₂ storage is primarily of interest where enhanced oil recovery is possible. These shortcomings and uncertainties mean that companies and governments today only have weak incentives to venture into geological CO₂ storage.     

Our future in the Anthropocene biosphere

The COVID-19 pandemic has exposed an interconnected and tightly coupled globalized world in rapid change. This article sets the scientific stage for understanding and responding to such change for global sustainability and resilient societies. We provide a systemic overview of the current situation where people and nature are dynamically intertwined and embedded in the biosphere, placing shocks and extreme events as part of this dynamic; humanity has become the major force in shaping the future of the Earth system as a whole; and the scale and pace of the human dimension have caused climate change, rapid loss of biodiversity, growing inequalities, and loss of resilience to deal with uncertainty and surprise. Taken together, human actions are challenging the biosphere foundation for a prosperous development of civilizations. The Anthropocene reality—of rising system-wide turbulence—calls for transformative change towards sustainable futures. Emerging technologies, social innovations, broader shifts in cultural repertoires, as well as a diverse portfolio of active stewardship of human actions in support of a resilient biosphere are highlighted as essential parts of such transformations.     

Fertilization trajectory of the root crop Raphanus sativus across atmospheric pCO2 estimates of the next 300 years

Plant biomass is known to increase in response to elevated atmospheric CO₂ concentration (pCO₂); however, no experiments have quantified the trajectory of crop fertilization across the full range of pCO₂ levels estimated for the next 300 years. Here we quantify the above- and below-ground biomass response of Raphanus sativus (common radish) across eight pCO₂ levels ranging from 348 to 1791 ppmv. We observed a large net biomass increase of 58% above ground and 279% below ground. A large part of the net increase (38% of the above-ground and 53% of the below-ground) represented biomass fertilization at the high levels of pCO₂ (700–1791 ppmv) predicted if fossil fuel emissions continue unabated. The trajectory of below-ground fertilization in R. sativus greatly exceeded a trajectory based on extrapolation of previous experiments for plants grown at pCO₂ < 800 ppmv. Based on the experimental parameters used to grow these plants, we hypothesize that these experiments represent the maximum CO₂ fertilization that can be achieved for this plant growing under low light levels. If the below-ground biomass enhancement that we have quantified for R. sativus represents a generalized root-crop response that can be extrapolated to agricultural systems, below-ground fertilization under very high pCO₂ levels could dramatically augment crop production in some of the poorest nations of the world, provided that water resources are sufficient and sustainable.     

Gene-TEQ--a standardized comparative assessment of effects in the comet assay using genotoxicity equivalents

Existing methods for the comparison of genotoxic effects in the comet assay bear considerable disadvantages such as the problem to link information about concentration dependence and severity of effects. Moreover, given the lack of standardized protocols and the use of various standards, it may be extremely difficult to compare different studies. In order to provide a method for standardized comparative assessment of genotoxic effects, the concept of genotoxicity equivalents (Gene-TEQ) was developed. As potential reference compounds for genotoxic effects, three directly acting (N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), methyl-methanesulfonate, and N-methyl-N-nitrosourea) and three indirectly acting (cyclophosphamide, dimethylnitrosamine, and 4-nitroquinoline-oxide) genotoxic substances were compared with respect to their cytotoxic (neutral red) and genotoxic (comet assay) concentration-response profiles in the permanent fish cell line RTL-W1. For further comparison, two sediment extracts from the upper Danube River were investigated as environmental samples. Based on the results of cytotoxicity and genotoxicity testing, MNNG was selected as the reference compound. At several exposure levels and durations, genotoxic effects of both the other pure substances and the environmental samples were calculated as percentages of the maximum MNNG effect and related to the absolute MNNG effect (EC values). Thus, genotoxicity equivalent factors (Gene-TEQs) relative to MNNG could be calculated. Gene-TEQs can easily be applied to pure substances, mixtures and field samples to provide information about their toxicity relative to the reference compound. Furthermore, the Gene-TEQ concept allows a direct comparison of environmental samples from different laboratories.     

Isolation and Identification of Microorganisms Able to Grow on the Polyester Amide BAK 1095

The polyester amide BAK 1095 is fully degraded by microorganisms. Bacteria that can grow on this polymer were isolated from various environments, such as freshwater, saltwater, arable land, woodland and compost. The mechanism of polymer degradation was examined using selected isolates. It was discovered that the bacteria selectively cleave the polymer at its ester bonds, releasing low-molecular water-soluble oligoamides. These can then be metabolised by other microorganisms [1, 2, 3]. The isolates were also tested for their ability to break down other ester-containing polymers such as Degranil W 50, a linear polyester urethane urea. Eight of the 12 strains examined were also able to break down this polymer.The isolated microorganisms predominantly belong to the genus Bacillus. Mesophilic, halophilic and thermophilic species were isolated. The studies show that polyester amide-degrading bacteria occur in numerous ecosystems and provide data on the microbial breakdown of random copolymers. Information was also obtained on the mechanism involved in the microbial breakdown of polyester amides.     

New Zealand drivers study: developing a methodology for conducting a follow-up study of newly licensed drivers

PROBLEM: In recent years, there has been a significant reduction in traffic crash injury among young people, but they continue to be overrepresented in the traffic crash statistics. To improve this situation, sound scientific evidence is needed to develop effective policies and programs. METHOD: The aim of the proposed study is to provide this evidence by examining early driving and driving-related experiences of newly licensed drivers as they progress through the learner-, restricted-, and full-license stages of the graduated licensing system and to determine the impact of these experiences on subsequent negative traffic-related outcomes (risky driving behavior, injury traffic crashes, noninjury traffic crashes, infringements, convictions). Given the size and complexity of the proposed study, a comprehensive pilot study was undertaken to determine the feasibility of conducting a New Zealand-wide cohort study of newly licensed drivers. RESULTS: This article describes the pilot study process and the methodology that has been developed for the New Zealand-wide study.