Quantifying Annual Nitrogen Loss to Groundwater Via Edge-of-Field Monitoring: Method and Application     

Michael Cardiff  Laura Schachter  Jake Krause  Madeline Gotkowitz  Brian Austin 《Ground water》2023,61(1):21-34

Increased nitrate concentrations in groundwater and surface waters represent one of the most widespread and acute impacts of modern agriculture on the environment. However, there is often a fundamental gap in understanding how individual agricultural fields and practices contribute to this broad-scale issue. To practically address nutrient dynamics at individual agricultural sites, methods for assessing nitrogen loss to groundwater that are minimally invasive and thus can encourage farmer “buy in” are necessary. We present an approach that uses edge-of-field monitoring at multilevel samplers along with a once-per-year tracer application (bromide) to calculate nitrogen loss on an annual basis. Using appropriate spatio-temporal integrals of measured concentrations, a net loss of nitrogen to groundwater (per field area) can be calculated. This approach directly measures impacts of nitrogen leaching below the water table, while avoiding permanent in-field installations that can interfere with farm operations. We present an application of this technique to assess nitrogen loss to groundwater over 5 years for a commercial agricultural field in Sauk County, WI. Results from Field 19 indicate that nitrogen losses are similar to (or slightly below) previously reported values for corn and potato crops. In all years, however, we estimate that more than 25% (>60 kg/ha) of nitrogen applied leached as nitrate to groundwater. Use of this mass flux estimation method was most reliable when: (1) tracer is injected directly at the water table, limiting “smearing” within the vadose zone; and (2) nitrate concentrations from laboratory analysis were obtained, rather than using ion-selective electrodes or nitrate test strips.  相似文献   

Biodiversity Conservation in the REDD   总被引：1，自引：0，他引：1  

Gary D Paoli  Philip L Wells  Erik Meijaard  Matthew J Struebig  Andrew J Marshall  Krystof Obidzinski  Aseng Tan  Andjar Rafiastanto  Betsy Yaap  JW Ferry Slik  Alexandra Morel  Balu Perumal  Niels Wielaard  Simon Husson  Laura D'Arcy 《Carbon balance and management》2010,5(1):1-9

Background

Forests occur across diverse biomes, each of which shows a specific composition of plant communities associated with the particular climate regimes. Predicted future climate change will have impacts on the vulnerability and productivity of forests; in some regions higher temperatures will extend the growing season and thus improve forest productivity, while changed annual precipitation patterns may show disadvantageous effects in areas, where water availability is restricted. While adaptation of forests to predicted future climate scenarios has been intensively studied, less attention was paid to mitigation strategies such as the introduction of tree species well adapted to changing environmental conditions.

Results

We simulated the development of managed forest ecosystems in Germany for the time period between 2000 and 2100 under different forest management regimes and climate change scenarios. The management regimes reflect different rotation periods, harvesting intensities and species selection for reforestations. The climate change scenarios were taken from the IPCC's Special Report on Emission Scenarios (SRES). We used the scenarios A1B (rapid and successful economic development) and B1 (high level of environmental and social consciousness combined with a globally coherent approach to a more sustainable development). Our results indicate that the effects of different climate change scenarios on the future productivity and species composition of German forests are minor compared to the effects of forest management.

Conclusions

The inherent natural adaptive capacity of forest ecosystems to changing environmental conditions is limited by the long life time of trees. Planting of adapted species and forest management will reduce the impact of predicted future climate change on forests.  相似文献   

Initial results in the development of a reporter cell line for toxicology studies at gene expression level: activation of the electrophile-responsive element by copper and methyl parathion     

Almeida DV  Trindade GS  Geracitano LA  Barros DM  Monserrat JM  Marins LF 《Marine environmental research》2008,66(1):158-160

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Antarctic marine chemical ecology: what is next?     

Conxita Avila  Sergi Taboada  & Laura Núñez-Pons 《Marine Ecology》2008,29(1):1-71

Antarctic ecosystems are exposed to unique environmental characteristics resulting in communities structured both by biotic interactions such as predation and competition, as well as abiotic factors such as seasonality and ice‐scouring. It is important to understand how ecological factors may trigger chemical mechanisms in marine Antarctic organisms as a response for survival. However, very little is known yet about the evolution of chemical compounds in Antarctic organisms. Investigations in chemical ecology have demonstrated over the last several years that defensive metabolites have evolved in numerous representative Antarctic species. This contradicts earlier theories concerning biogeographic variation in predation and chemical defenses. As reviewed here, a number of interesting natural products have been isolated from Antarctic organisms. However, we believe many more are still to be discovered. Currently, many groups such as microorganisms, planktonic organisms and deep‐sea fauna remain almost totally unknown regarding their natural products. Furthermore, for many described compounds, ecological roles have yet to be evaluated. In fact, much of the research carried out to date has been conducted in the laboratory, and only in a few cases in an ecologically relevant context. Therefore, there is a need to extend the experiments to the field, as done in tropical and temperate marine ecosystems, or at least, to test the activity of the chemicals in natural conditions and ecologically meaningful interactions. Defense against predators is always one of the main topics when talking about the roles of natural products in species interactions, but many other interesting aspects, such as competition, chemoattraction, fouling avoidance and ultraviolet (UV) protection, also deserve further attention. In our opinion, challenging future developments are to be expected for Antarctic marine chemical ecology in the years to come.  相似文献   

Seasonal changes of antioxidant and oxidative parameters in the coral Pocillopora capitata on the Pacific coast of Mexico     

Marco A. Liñán‐Cabello  Laura A. Flores‐Ramírez  Tania Zenteno‐Savin  Norma O. Olguín‐Monroy  Ramón Sosa‐Avalos  Manuel Patiño‐Barragan  Aramis Olivos‐Ortiz 《Marine Ecology》2010,31(3):407-417

The physiological responses of the coral Pocillopora capitata to environmental conditions common in winter and summer were studied in 2007 during February–March (winter) and June–July (summer) at La Boquita reef (Manzanillo, Colima, Mexico). Shallow and deep sampling stations were established at different distances from a small jetty built next to the Juluapan Lagoon. We analyzed superoxide radicals () and lipid peroxidants (TBARS); the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione‐S‐transferase (GST); chlorophyll a (Chl a), zooxanthellae density (ZD); and mycosporine‐like amino acids (MAAs). Our results showed that the , TBARS, CAT, GST, MAAs, and Chl a, levels were significantly higher in summer (P < 0.05); no seasonal difference was found for GPx, GR or ZD. We found significant differences (P < 0.05) in winter only for Chl a and ZD at shallow sites and, in contrast, for at deeper sites. The results of this study indicate that increasing temperature and radiation associated with seasonal changes (from winter to summer), the efficiency of the enzymes GST, CR and GPX, and the production of MAAs together form a powerful mechanism for P. capitata to offset the detrimental effects of environmental change.  相似文献   

Early onset of a microcystin-producing cyanobacterial bloom in an agriculturally-influenced Great Lakes tributary     

Mckay  Robert Michael L.  Tuttle  Taylor  Reitz  Laura A.  Bullerjahn  George S.  Cody  William R.  McDowell  Adam J.  Davis  Timothy W. 《中国海洋湖沼学报》2018,36(4):1112-1125

In late May 2016, a cyanobacterial harmful algal bloom(cHAB) was detected in the Maumee River, the largest tributary to Lake Erie, the southernmost lake of the Laurentian Great Lakes system. Testing on 31 May identified Planktothrix agardhii as the dominant cyanobacterium with cell abundance exceeding 1.7×10~9 cells/L and total microcystins(MC) reaching 19 μg/L MC-LR equivalents, a level over 10-fold higher than the 2015 revised U.S. Environmental Protection Agency(EPA) national health advisory levels for drinking water exposure to adults. Low river discharge coincident with negligible precipitation through the latter half of May coincided with an 80% decline in river turbidity that likely favored bloom formation by a low-light adapted P. agardhii population. Also contributing to the c HAB were high initial nutrient loads and an increase of the river temperature from 13℃ to 26℃ over this same period. The bloom persisted through 5 June with microcystins exceeding 22 μg/L MC-LR equivalents at the bloom peak. By 6 June, the river had returned to its muddy character following a rain event and sampling on 7 June detected only low levels of toxin(0.6 μg/L) at public water systems located near the bloom origin. The elevated toxin production associated with this early onset bloom was without precedent for the Maumee River and an unique attribute of the c HAB was the high proportion of potentially-toxic genotypes. Whereas Planktothrix spp. is common in lotic environments, and has been previously detected in the Maumee, blooms are not commonly reported. This early onset, microcystin-producing c HAB provided a rare opportunity to glean insights into environmental factors that promote bloom development and dominance by Planktothrix in lotic environments.  相似文献   

Hydroid assemblages from the Southwestern Atlantic Ocean (34–42° S)     

Gabriel N. Genzano  Diego Giberto  Laura Schejter  Claudia Bremec  & Pablo Meretta 《Marine Ecology》2009,30(1):33-46

This paper provides updated taxonomic knowledge about hydrozoan species and provides ecological information including geographical and bathymetric distributions and biological substrata for the various hydroid assemblages from the Sub-Antarctic Biogeographical Region, mainly Buenos Aires and the Uruguayan coasts. Five of the 41 species found are new records for the study region. Thirty-one species (75.6%), all found at depths of less than 80 m, have cosmopolitan distributions. Biodiversity decreased markedly below 80 m depth, where nine species (≈22%) distributed in the Southern hemisphere and one endemic species (2.4%) were found. Most species were non-specific epizoites, occurring on diverse substrata. A non-parametric multivariate similarity analysis revealed nine species groups that were correlated with large-scale and local oceanographic patterns and with the availability of suitable substrata. The main hydroid substrata for eight of the groups were cnidarians, molluscs (mainly blue mussels), quartzite rocks and sponges. In a single group found in Patagonian scallop beds, the main biological substrata were polychaete tubes, other hydroids and scallops.  相似文献   

Telecentres in mountain regions — A Peruvian case study of the impact of information and communication technologies on remoteness and exclusion     

Richard Heeks  Laura León Kanashiro 《山地科学学报》2009,6(4):320-330

Communities in developing country mountain areas, in part due to their remoteness, find themselves excluded from social, political and economic systems; and excluded from access to resources. This paper aims to study the impact of information and communication technologies （ICTs） on remoteness and exclusion. It utilises two models - the resource movement framework, and the ＂information chain＂ - to analyse a telecentre in one district of mountainous Huancavelica, Peru＇s poorest region, set in the high Andes. It finds ICTs enabling new and positive resource flows for the two key user groups： teenaged school students and young farmers. These help to maintain social networks. They also support information searches that have improved agricultural practice where other information chain resources have been available. But non-use and ineffective use of the telecentre are found where information chain resources are lacking. ICTs have some impacts on intangible elements of remoteness. In this particular example, they also offer access to some previously-excluded resources. But they have not really addressed the systematic exclusions faced by mountain communities. And they so far appear to be a technology of inequality; favouring those residents who begin with better resource endowments. The paper concludes by offering some recommendations for mountain ICT project practice.  相似文献   

gvSOS: A New Client for the OGC® Sensor Observation Service Interface Standard     

Alain Tamayo  Joaquín Huerta  Carlos Granell  Laura Díaz  Ricardo Quirós 《Transactions in GIS》2009,13(S1):47-61

A key problem with sensor networks is achieving interoperability between different networks potentially built using different software and hardware platforms. Services interfaced by the Open Geospatial Consortium (OGC) specifications allow GIS clients to access geospatial data without knowing the details about how these data are gathered or stored. Currently, OGC is working on a set of interoperable interfaces and metadata encodings known as Sensor Web Enablement (SWE) that enables the integration of heterogeneous sensor systems and measurements into geospatial information infrastructures. In this article we present the implementation of gvSOS, a new module for gvSIG to connect to Sensor Observation Services (SOS). The gvSOS client module allows gvSIG users to interact with SOS servers, displaying the information gathered by sensors as a layer composed by features. We present the software engineering development process followed to build the module. For each step of the process we specify the main obstacles found during the development such as restrictions of the gvSIG architecture, inaccuracies in the OGC specifications, and a set of common problems found in current SOS server implementations available on the Internet. For most of the problems found we propose a solution, or at least we present a path that might lead to it.  相似文献