Effects of stream channelization on exports of nitrogen and phosphorus from north Carolina coastal plain watersheds

Nitrogen and phosphorus exports from channelizedstream watersheds were elevated over those from nearby natural swamp-stream watersheds. Nitrate exports were significantly greater from channelized-stream watersheds, and higher exports were attributed to faster groundwater drawdown, continual streamflow, and transformation of former floodplain to croplands following channelization. Exports of total organic nitrogen and total nitrogen were also significantly greater from channelized-stream watersheds. Differences in the exports of ammonium, filterable reactive phosphorus, and filterable unreactive phosphorus between the two watershed types were not detectable. Particulate phosphorus exports were significantly higher from channelized-stream watersheds, presumably because of greater erosion potential of nearby croplands and steep channel banks in the altered watersheds. The presence of nonpoint sources of pollution increased watershed exports of nutrients regardless of stream morphology. Examination of nutrient budgets for a portion of swamp floodplain at the base of one natural-stream watershed revealed that changes in local groundwater hydrology and stream morphology associated with channelization appeared to have greater effect on nutrient exports than simply the loss of bordering forested floodplain.     

Spatial Extent Of Degraded Sediment Quality In Puget Sound (Washington State, U.S.A.) Based Upon Measures Of The Sediment Quality Triad

A survey was designed and conducted to determine the severity, spatial patterns, and spatial extent of degraded sediment quality in Puget Sound (Washington State, USA). A weight of evidence compiled from results of chemical analyses, toxicity tests, and benthic infaunal analyses was used to classify the quality of sediments. Sediment samples were collected from 300 locations within a 2363 km² area extending from the US/Canada border to the inlets of southern Puget Sound and Hood Canal. Degraded conditions, as indicated with a combination of high chemical concentrations, significant toxicity, and adversely altered benthos, occurred in samples that represented about 1% of the total area. These conditions invariably occurred in samples collected within urbanized bays and industrial waterways, especially near the urban centers of Everett, Seattle, Tacoma, and Bremerton. Sediments with high quality (as indicated by no toxicity, no contamination, and the presence of a relatively abundant and diverse infauna) occurred in samples that represented a majority (68%) of the total study area. Sediments in which results of the three kinds of analyses were not in agreement were classified as intermediate in quality and represented about 31% of the total area. Relative to many other estuaries and marine bays of the USA, Puget Sound sediments ranked among those with minimal evidence of toxicant-induced degradation.     

Incidence of stress in benthic communities along the U.S. Atlantic and Gulf of Mexico coasts within different ranges of sediment contamination from chemical mixtures

Synoptic data on concentrations of sediment-associated chemical contaminants and benthic macroinfaunal community structure were collected from 1,389 stations in estuaries along the U.S. Atlantic and Gulf of Mexico coasts as part of the nationwide Environmental Monitoring and Assessment Program (EMAP). These data were used to develop an empirical framework for evaluating risks of benthic community-level effects within different ranges of sediment contamination from mixtures of multiple chemicals present at varying concentrations. Sediment contamination was expressed as the mean ratio of individual chemical concentrations relative to corresponding sediment quality guidelines (SQGs), including Effects Range-Median (ERM) and Probable Effects Level (PEL) values. Benthic condition was assessed using diagnostic, multi-metric indices developed for each of three EMAP provinces (Virginian, Carolinian, and Louisianian). Cumulative percentages of stations with a degraded benthic community were plotted against ascending values of the mean ERM and PEL quotients. Based on the observed relationships, mean SQG quotients were divided into four ranges corresponding to either a low, moderate, high, or very high incidence of degraded benthic condition. Results showed that condition of the ambient benthic community provides a reliable and sensitive indicator for evaluating the biological significance of sediment-associated stressors. Mean SQG quotients marking the beginning of the contaminant range associated with the highest incidence of benthic impacts (73–100% of samples, depending on the province and type of SQG) were well below those linked to high risks of sediment toxicity as determined by short-term toxicity tests with single species. Measures of the ambient benthic community reflect the sensitivities of multiple species and life stages to persistent exposures under actual field conditions. Similar results were obtained with preliminary data from the west coast (Puget Sound).     

A national ozone biomonitoring program--results from field surveys of ozone sensitive plants in northeastern forests (1994-2000)

Ozone biomonitoring is a detection and monitoring techniquethat involves documenting ozone-induced visible injury toknown ozone-sensitive species under conditions of ambientexposure. The USDA Forest Service administers a long-term,nationwide ozone biomonitoring program to address public andscientific concerns about ozone impacts on forest health. Asystematic grid is used as the basis for biomonitoring sitelocations. At each site, trained field crews evaluate amaximum of thirty plants of up to six species and record the amount and severity of leaf-injury on individualplants. Injury from ozone was found more often on biomonitoring sites in the eastern Unites States than in theinterior or west-coast areas. Further results from thenortheast reveal that in any year, there is a higherpercentage of ozone-injured plants with more severe symptomsin areas with relatively high ozone concentrations than inareas with relatively low ozone. In very dry years (e.g.,1999) the percentage of injured plants and injury severityestimates are both sharply reduced even though ambient ozoneexposures are high. These findings demonstrate thatbiomonitoring data provide meaningful evidence of when highozone concentrations during the growing season have biologicalsignificance. Any assessment of ozone stress in the forestenvironment must include both biomonitoring (i.e., plantresponse) and air quality data to be complete.     

Environmental health implications of global climate change

This paper reviews the background that has led to the now almost-universally held opinion in the scientific community that global climate change is occurring and is inescapably linked with anthropogenic activity. The potential implications to human health are considerable and very diverse. These include, for example, the increased direct impacts of heat and of rises in sea level, exacerbated air and water-borne harmful agents, and--associated with all the preceding--the emergence of environmental refugees. Vector-borne diseases, in particular those associated with blood-sucking arthropods such as mosquitoes, may be significantly impacted, including redistribution of some of those diseases to areas not previously affected. Responses to possible impending environmental and public health crises must involve political and socio-economic considerations, adding even greater complexity to what is already a difficult challenge. In some areas, adjustments to national and international public health practices and policies may be effective, at least in the short and medium terms. But in others, more drastic measures will be required. Environmental monitoring, in its widest sense, will play a significant role in the future management of the problem.     

Changes in housing in Guatemala following the 1976 earthquake: With special reference to earthen structures and how they are perceived by disaster victims*

This paper reports on what has happened to earthen structures in 26 Guatemalan communities studied over a 4-year period since the 1976 earthquake. The data were obtained from three waves of personal interviews with 1472 randomly sampled household heads. The results show that adobe, which was the primary housing material before the earthquake was heavily damaged in that event. As a consequence the number of adobe structures and of other earthen structures has been drastically reduced. The people of Guatemala individually and because of agency housing programs have abandoned adobe as a building material and turned to concrete block and wood. Surviving earthen structures have not been improved substantially and remain with largely the same structural features as before the earthquake. The greatest improvement is in the use of comer posts or columns in the walls but most of these are made of untreated crude logs or lumber, subject to rot and termite damage. Little information on aseismic housing seems to have spread either within the earthquake area or in the unaffected areas surrounding it. A program to spread information on how to use adobe in aseismic designs needs to be conducted along with one to assist citizens to aquire the resources necessary to improve the earthquake vulnerability of houses.     

Experimental design of the Svalbard shoreline field trials

Experimental oil spills on three mixed-sediment beaches in Svalbard, Norway, were designed to evaluate the effectiveness of in situ shoreline cleaning treatments to accelerate natural recovery. These were: sediment relocation (surf washing), mixing (tilling), bioremediation (fertilizer application), and bioremediation combined with mixing. Additionally, natural attenuation was studied as a treatment option. An intermediate fuel oil was applied to the sediment surface in the upper intertidal zone at three experimental sites, each of which had different sediment characteristics and wave-energy exposure. Over a 400-day period, the experiments quantified oil removal, documented changes in the physical character of the beach as well as oil fate and behaviour, assessed toxicity effects associated with treatment, and validated oil-mineral aggregate formation as a result of the selected treatment techniques. The three sites were chosen based on significant differences, and each treatment was quantitatively compared only with other treatments at that site.This paper describes the physical location and the experimental design of the field trials. Some of the key issues that were addressed in the design included: the methodology for application of oil, the application of treatment techniques, the realistic simulation of real-world conditions, and the sampling protocols to overcome sediment and oiling heterogeneity typical of mixed-sediment beaches in order to allow quantitative comparisons of the treatments.     

In-situ Treatment of Oiled Sediment Shorelines

Experimental oil spill studies were conducted to quantify the effectiveness of selected in-situ shoreline treatment options to accelerate natural oil removal processes on mixed-sediment (sand and pebble) shorelines. At each of three distinct shoreline sites, treatment test plots and control plots were established within a 40-, 80- and 143-m continuous stretch of oiled shoreline. A total of 5500 l of oil was deposited along a 3-m wide swath in the upper intertidal zone at each site. Approximately one week after oiling, a different treatment technique was applied to each plot. The treatment techniques were: sediment relocation (surf washing), mixing (tilling), bioremediation (fertilizer application), and bioremediation combined with mixing. One plot at each site was monitored for natural attenuation. The quantity of oil removed from the plots was measured six times up to 60 days post-treatment and then again one year later. Changes in the physical character of the beach, oil penetration, movement of oil to the subtidal environment, toxicity, and biodegradation were monitored over the 400-day period.The results verified quantitatively that relocation of oiled sediments significantly accelerated the rate of oil removal from the shoreline by more than one year. Microscopic observations and image analyses confirmed that the oil-mineral aggregate formation process was active and was increased by sediment relocation. Oil biodegradation occurred in this arctic environment, both in the oiled sediments and on the fine mineral particles removed from the sediment by natural physical processes. The biodegradation of oil in sediment was significantly stimulated by simple bioremediation protocols. Mixing (by tilling) did not clearly stimulate oil loss and natural recovery in the context of this experimental design. None of the treatment techniques elevated toxicity in the nearshore environment to unacceptable levels, nor did they result in consequential alongshore or nearshore oiling.     

Assessing non‐metro recovery across two continents: issues and limitations

Rural and remote areas of countries such as Australia and the United States are less well‐resourced and often poorer than their city counterparts. When a disaster strikes, therefore, their long‐term recovery can be impeded by being situated ‘over the horizon'. Nonetheless, they are likely to enjoy higher social capital, with ‘locals’ banding together to help restore economic and social life in the wake of a calamitous incident. At the same time, a repeat of extreme events, springing in part from alteration to the landscape through intense human occupation, threatens to derail sustainable recovery processes everywhere, suggesting that renewed emphasis needs to be placed on preparedness. Improved metrics are also required, spanning both pre‐ and post‐disaster phases, to determine effectiveness. Moreover, a focus on the ‘hardening’ of towns offers a better return in limiting damage and potentially hastens the speed of recovery should these places later fall victim to extreme events.