In situ ground water denitrification in stratified, permeable soils underlying riparian wetlands

The ground water denitrification capacity of riparian zones in deep soils, where substantial ground water can flow through low-gradient stratified sediments, may affect watershed nitrogen export. We hypothesized that the vertical pattern of ground water denitrification in riparian hydric soils varies with geomorphic setting and follows expected subsurface carbon distribution (i.e., abrupt decline with depth in glacial outwash vs. negligible decline with depth in alluvium). We measured in situ ground water denitrification rates at three depths (65, 150, and 300 cm) within hydric soils at four riparian sites (two per setting) using a 15N-enriched nitrate "push-pull" method. No significant difference was found in the pattern and magnitude of denitrification when grouping sites by setting. At three sites there was no significant difference in denitrification among depths. Correlations of site characteristics with denitrification varied with depth. At 65 cm, ground water denitrification correlated with variables associated with the surface ecosystem (temperature, dissolved organic carbon). At deeper depths, rates were significantly higher closer to the stream where the subsoil often contains organically enriched deposits that indicate fluvial geomorphic processes. Mean rates ranged from 30 to 120 microg N kg(-1) d(-1) within 10 m versus <1 to 40 microg N kg(-1) d(-1) at >30 m from the stream. High denitrification rates observed in hydric soils, down to 3 m within 10 m of the stream in both alluvial and glacial outwash settings, argue for the importance of both settings in evaluating the significance of riparian wetlands in catchment-scale N dynamics.     

The city as a refuge for insect pollinators

Research on urban insect pollinators is changing views on the biological value and ecological importance of cities. The abundance and diversity of native bee species in urban landscapes that are absent in nearby rural lands evidence the biological value and ecological importance of cities and have implications for biodiversity conservation. Lagging behind this revised image of the city are urban conservation programs that historically have invested in education and outreach rather than programs designed to achieve high‐priority species conservation results. We synthesized research on urban bee species diversity and abundance to determine how urban conservation could be repositioned to better align with new views on the ecological importance of urban landscapes. Due to insect pollinators’ relatively small functional requirements—habitat range, life cycle, and nesting behavior—relative to larger mammals, we argue that pollinators put high‐priority and high‐impact urban conservation within reach. In a rapidly urbanizing world, transforming how environmental managers view the city can improve citizen engagement and contribute to the development of more sustainable urbanization.     

Effect on plant growth parameters and secondary metabolite content of lettuce (Lactuca sativa L.), coriander (Coriandrum sativum), and chili pepper (Capsicum annuum L.) watered with disinfected water by Ag-TiO2 nanoparticles

Environmental Science and Pollution Research - Nowadays, the use of different nanoscale structures has been introduced to a large number of research areas. One of these is the treatment and...     

Comparison of Outdoor and Classroom Ozone Exposures for School Children in Mexico City

Abstract

To evaluate methods of reducing exposure of school children in southwest Mexico City to ambient ozone, outdoor ozone levels were compared to indoor levels under three distinct classroom conditions: windows/doors open, air cleaner off; windows/doors closed, air cleaner off; windows/ doors closed, air cleaner on. Repeated two-minute average measurements of ozone were made within five minutes of each other inside and outside of six different school classrooms while children were in the room. Outdoor ozone two-minute average levels varied between 64 and 361 ppb; mean outdoor levels were above 160 ppb for each of the three conditions. Adjusting for outdoor relative humidity, for a mean outdoor ozone concentration of 170 ppb, the mean predicted indoor ozone concentrations were 125.3 (±5.7) ppb with windows/doors open; 35.4 (±4.6) ppb with windows/ doors closed, air cleaner off; and 28.9 (±4.3) ppb with windows/ doors closed, air cleaner on. The mean predicted ratios of indoor to outdoor ozone concentrations were 0.71 (±0.03) with windows/doors open; 0.18 (±0.02) ppb with windows/doors closed, air cleaner off; and 0.15 (±0.02) ppb with windows/doors closed, air cleaner on. As outdoor ozone concentrations increased, indoor ozone concentrations increased more rapidly with windows and doors open than with windows and doors closed. Ozone exposure in Mexican schools may be significantly reduced, and can usually be kept below the World Health Organization (WHO) guideline of 80 ppb, by closing windows and doors even when ambient ozone levels reach 30Q ppb or more.     

An Air Quality Modeling Study Comparing Two Possible Sites for the New International Airport for Mexico City

Abstract

Using an air quality model, two future urban scenarios induced by the construction of the new international airport for Mexico City are compared at a regional level. The air quality model couples the meteorology model MM5 and state-of-the-art photochemistry. The air quality comparison is made using metrics for the criterion gases selected for the study. From the two urban scenarios compared, the option for Tizayuca is moderately better than the option for Texcoco, because relative reductions in O₃ and other photochemical pollutants are achieved over highly populated areas. Regardless of the site, the air quality for the central region of Mexico in the future will deteriorate. In the region of central Mexico, SO₂ and NO₂ will become important pollutants.     

Contaminants in the coastal karst aquifer system along the Caribbean coast of the Yucatan Peninsula, Mexico

Intensive land development as a result of the rapidly growing tourism industry in the “Riviera Maya” region of the Yucatan Peninsula, Mexico may result in contamination of groundwater resources that eventually discharge into Caribbean coastal ecosystems. We deployed two types of passive sampling devices into groundwater flowing through cave systems below two communities to evaluate concentrations of contaminants and to indicate the possible sources. Pharmaceuticals and personal care products accumulated in the samplers could only have originated from domestic sewage. PAHs indicated contamination by runoff from highways and other impermeable surfaces and chlorophenoxy herbicides accumulated in samplers deployed near a golf course indicated that pesticide applications to turf are a source of contamination. Prevention and mitigation measures are needed to ensure that expanding development does not impact the marine environment and human health, thus damaging the tourism-based economy of the region.     

A Novel Formulation for Designing a Monitoring Strategy: Application to the Design of a River Quality Monitoring System

In this work, we propose a technique to automatically optimize the monitoring of any distributed indicator (concentration of a substance along a river, blood pressure of a patient over time, etc.) for which a reliable estimate is previously available. From a mathematical point of view, the problem is based on obtaining a reliable estimate of the chosen indicator (e.g., by numerical simulation), and then solving a multi-objective optimization problem (with mixed real and integer variables) whose solution must provide an efficient and satisfactory monitoring strategy. As an illustrative case, we show the steps to follow in order to implement that strategy when designing a system for monitoring water quality in a river. Finally, we present and analyze the results when applying the proposed technique to study a real case in the Neuse River (North Carolina, USA).     

Effects of induced paralysis on hemocytes and tissues of the giant lions-paw scallop by paralyzing shellfish poison

In general, bivalves are not affected by exposure to toxic dinoflagellates that produce paralyzing shellfish poisons (PSP). After injection with PSP extracted from the Gymnodinium catenatum, Nodipecten subnodosus is paralyzed, indicating that PSP provokes effects similar to what is observed in vertebrates, including paralysis and metabolic stress. To investigate the processes involved in poisoning by PSP, lions-paw scallops were injected with gonyautoxin (GTX) 2/3 epimers in the adductor muscle. Mild doses provoked adductor muscle contractions and paralysis, mantle retraction, and incapacity of shell closure, but scallops gradually recovered in a clear, dose-time recovery pattern. With high doses of GTX 2/3, scallops were permanently paralyzed, and hemocytes in hemolymph were reduced. Surprisingly, under these conditions, scallops continued normal feeding and did not show any microscopic defect in intestine or gills, but hemocytes infiltrated the adductor muscle and abnormal vitellogenesis and mantle melanization occurred. Paralysis stress was accompanied by negative scallop responses, based on visible effects, generation of nitric oxide, lipid peroxidation, and changes in antioxidant and hydrolytic enzymes in hemocytes and tissues. These data can be used to understand potential side effects of PSP in bivalves.     

A Framework of Lessons Learned from Community-Based Marine Reserves and Its Effectiveness in Guiding a New Coastal Management Initiative in the Philippines

Community-based coastal resource management has been widely applied within the Philippines. However, small-scale community-based reserves are often inefficient owing to management inadequacies arising because of a lack of local support or enforcement or poor design. Because there are many potential pitfalls during the establishment of even small community-based reserves, it is important for coastal managers, communities, and facilitating institutions to have access to a summary of the key factors for success. Reviewing relevant literature, we present a framework of lessons learned during the establishment of protected areas, mainly in the Philippines. The framework contains summary guidance on the importance of (1) an island location, (2) small community population size, (3) minimal effect of land-based development, (4) application of a bottom-up approach, (5) an external facilitating institution, (6) acquisition of title, (7) use of a scientific information database, (8) stakeholder involvement, (9) the establishment of legislation, (10) community empowerment, (11) alternative livelihood schemes, (12) surveillance, (13) tangible management results, (14) continued involvement of external groups after reserve establishment, and (15) small-scale project expansion.These framework components guided the establishment of a community-based protected area at Danjugan Island, Negros Occidental, Philippines. This case study showed that the framework was a useful guide that led to establishing and implementing a community-based marine reserve. Evaluation of the reserve using standard criteria developed for the Philippines shows that the Danjugan Island protected area can be considered successful and sustainable. At Danjugan Island, all of the lessons synthesized in the framework were important and should be considered elsewhere, even for relatively small projects. As shown in previous projects in the Philippines, local involvement and stewardship of the protected area appeared particularly important for its successful implementation. The involvement of external organizations also seemed to have a key role in the success of the Danjugan Island project by guiding local decision-makers in the sociobiological principles of establishing protected areas. However, the relative importance of each component of the framework will vary between coastal management initiatives both within the Philippines and across the wider Asian region.Published on line     

Identifying riparian sinks for watershed nitrate using soil surveys

The capacity of riparian zones to serve as critical control locations for watershed nitrogen flux varies with site characteristics. Without a means to stratify riparian zones into different levels of ground water nitrate removal capacity, this variability will confound spatially explicit source-sink models of watershed nitrate flux and limit efforts to target riparian restoration and management. We examined the capability of SSURGO (1:15 840 Soil Survey Geographic database) map classifications (slope class, geomorphology, and/or hydric soil designation) to identify riparian sites with high capacity for ground water nitrate removal. The study focused on 100 randomly selected riparian locations in a variety of forested and glaciated settings within Rhode Island. Geomorphic settings included till, outwash, and organic/alluvial deposits. We defined riparian zones with "high ground water nitrate removal capacity" as field sites possessing both >10 m of hydric soil width and an absence of ground water surface seeps. SSURGO classification based on a combination of geomorphology and hydric soil status created two functionally distinct sets of riparian sites. More than 75% of riparian sites classified by SSURGO as organic/alluviumhydric or as outwash-hydric had field attributes that suggest a high capacity for ground water nitrate removal. In contrast, >85% of all till sites and nonhydric outwash sites had field characteristics that minimize the capacity for ground water nitrate removal. Comparing the STATSGO and SSURGO databases for a 64000-ha watershed, STATSGO grossly under-represented critical riparian features. We conclude that the SSURGO database can provide modelers and managers with important insights into riparian zone nitrogen removal potential.