Effects of restoration and reflooding on soil denitrification in a leveed Midwestern floodplain.

River floodplains have the potential to remove nitrate from water through denitrification, the anaerobic microbial conversion of nitrate to nitrogen gas. An important factor in this process is the interaction of river water with floodplain soil; however, many rivers have been disconnected from their historic floodplains by levees. To test the effect of reflooding a degraded floodplain on nitrate removal, we studied changes in soil denitrification rates on the Baraboo River floodplain in Wisconsin, USA, as it underwent restoration. Prior to this study, the site had been leveed, drained, and farmed for more than 50 years. In late fall 2002, the field drainage system was removed, and a gate structure was installed to allow controlled flooding of this site with river water. Soil moisture was extremely variable among zones and months and reflected local weather. Soil organic matter was stable over the study period with differences occurring along the elevation gradient. High soil nitrate concentrations occurred in dry, relatively organic-poor soil samples and, conversely, all samples with high moisture soils characterized by low nitrate. We measured denitrification in static cores and potential denitrification in bulk samples amended with carbon and nitrogen, one year before and two years following the manipulation. Denitrification rates showed high temporal and spatial variability. Static core rates of individual sites ranged widely (from 0.00 to 16.7 microg N2O-N x [kg soil](-1) x h(-1), mean +/- SD = 1.10 +/- 3.02), and denitrification enzyme activity (DEA) rates were similar with a slightly higher mean (from 0.00 to 15.0 microg N2O-N x [kg soil](-1) x h(-1), 1.41 +/- 1.98). Denitrification was not well-correlated with soil nitrate, organic matter content, or moisture levels, the three parameters typically thought to control denitrification. Static core denitrification rates were not significantly different across years, and DEA rates decreased slightly the second year after restoration. These results demonstrate that restored agricultural soil has the potential for denitrification, but that floodplain restoration did not immediately improve this potential. Future floodplain restorations should be designed to test alternative methods of increasing denitrification.     

Inorganic nitrogen metabolism in marine bacteria: The intracellular free amino acid pools of a marine pseudomonad

The marine pseudomonad bacterium PL₁ contains an intracellular pool of free amino acids which consist mainly of glutamate with small amounts of glutamine and aspartate when grown in a nutrient medium containing 0.2 M NaCl. When the NaCl concentration of the growth medium is increased to 0.8 M, proline becomes a major component of the intracellular pool together with glutamate—at this molarity and under suitable nutrient conditions these amino acids comprise 20% of total bacterial amino acid nitrogen. When grown in a nutrient growth medium containing a constant level of NaCl, the intracellular pool size can vary by a factor of 4 depending on the concentration of carbon and nitrogen in the medium. Experiments show that the amino acid pool can act as a nitrogen reserve but has little function as a carbon reserve. At high NaCl concentrations there is a marked dependence for growth on the presence of sufficient potassium in the medium. However, no correlation between K⁺ and glutamate concentration in either nitrogen or K⁺-limited cultures has been found. None of the enzymes associated with glutamate biosynthesis was influenced by NaCl levels between 0.2 and 0.5 M. Neither Na⁺ or K⁺ stimulated the activity of these enzymes when tested in vitro.     

Sustainability and education for sustainability: An analysis of publications from the last decade

This study analyzes the characteristics of publications on sustainability topics and education for sustainability in the Web of Science (WOS) database during the period ranging from 2005 to 2014. We identified the topics that are being studied within those subjects and other relevant topics. We also analyzed a special edition of the Journal of Cleaner Production on “Higher Education for Sustainable Development: Emerging areas,” published in January, 2014. Our approach was both qualitative and quantitative and aimed at qualifying and quantifying certain variables related to the scientific literature on the broad subject of sustainability. The number of published pieces in the WOS focusing on sustainability issues during the period from 2005 to 2014 was 5,924. In our analysis of the special edition of the Journal of Cleaner Production, we found and analyzed 17 abstracts and full papers. The main results of our survey highlight the education, educational research, environmental sciences, ecology, and engineering areas as including the greatest number of publications. Articles, as opposed to conference proceedings or reviews, accounted for 63% of the published documents, and the year 2013 showed the largest number of publications. Huisingh, Suciu, Katane, and Barth are the most published authors on these topics. Furthermore, management, environmental studies, ecology, and environmental sciences are the “hot topics” with the best search results, meaning articles of impact and high quality. Finally, it should be emphasized that publications on the subject of sustainability appear most often in the sciences.     

Somatic Coliphage Profiles of Produce and Environmental Samples from Farms in Northern México

Somatic coliphages were quantified in 459 produce and environmental samples from 11 farms in Northern Mexico to compare amounts of somatic coliphages among different types of fresh produce and environmental samples across the production steps on farms. Rinsates from cantaloupe melons, jalapeño peppers, tomatoes, and the hands of workers, soil, and water were collected during 2011–2012 at four successive steps on each farm, from the field before harvest through the packing facility, and assayed by FastPhage MPN Quanti-tray method. Cantaloupe farm samples contained more coliphages than jalapeño or tomato (p range <0.01–0.03). Across production steps, jalapeños had higher coliphage percentages before harvest than during packing (p = 0.03), while tomatoes had higher coliphage concentrations at packing than all preceding production steps (p range <0.01–0.02). These findings support the use of targeted produce-specific interventions at multiple points in the process of growing and packing produce to reduce the risk of enteric virus contamination and improve food safety during fruit and vegetable production.     

Assessment of geochemical modeling applications and research hot spots—a year in review

Environmental Geochemistry and Health - Geochemical modeling has been employed in several fields of science and engineering in recent years. This review seeks to provide an overview of case studies...     

Morphological and statistical analysis of the impact of breakwaters under construction on a sand spit area (Douro River estuary)

The area of Cabedelo sand spit, located at the mouth of Douro River estuary (Porto, Portugal), reduced in recent decades. In order to study its evolution and also the impact of two breakwaters built to fix the river entrance, a dataset from 23 trimestral surveys using differential GPS techniques, conducted between 2001 and 2007, were considered. A time-series analysis and the estimation of relationships between Cabedelo spit area and several hydrodynamic parameters through statistical techniques were performed in order to determine which parameters have more influence in the Cabedelo spit behavior. From the time-series analysis a seasonal tendency is visible, with the lower values occurring in December and the higher values occurring in July. The estimation of a relationship between Cabedelo spit area and several independent variables reached better results when the dataset was divided in Part A (before the beginning of breakwaters construction) and Part B (during the breakwaters construction). An analysis of the morphological evolution of Cabedelo spit shoreline was also performed: (1) a simple analysis of retreat and accretion rates data with a geographical information system and (2) a more exhaustive analysis were performed using Empirical Orthogonal Functions (EOFs). The Cabedelo spit shoreline erosion occurs mostly on the West and North side, and the accretion mostly occurs in the area protected by the South breakwater. During the breakwater’s construction, the Cabedelo spit shoreline presented high retreat rates, with a mean value greater than 100 m. In terms of spatial variance (EOFs analysis), when the dataset was divided in two parts, the first Principal Component (PC) represents 60.10 % and 89.86 % of the mean squared value of the data, for Part A and Part B, respectively. As proved, the breakwaters would tend to stabilize the coastline leading to a higher first PC value after breakwaters construction (Part B).