Assessment Of Long-term Trends Research Articles

Passive sampling: An effective method for monitoring seasonal and spatial variability of dissolved hydrophobic organic contaminants and metals in the Danube river

Application of passive samplers is demonstrated for assessment of temporal and spatial trends of dissolved polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and priority metals in the middle stretch of the Danube river. Free dissolved concentrations of PAHs, measured using SPMD samplers, ranged from 5 to 72 ng L−1. Dissolved PCBs in water were very low and they ranged from 5 to 16 pg L−1. Concentration of mercury, cadmium, lead and nickel, measured using DGT samplers, were relatively constant along the monitored Danube stretch and in the range <0.1, <1–20, 18–74, and 173–544 ng L−1, respectively. Concentrations of PAHs decreased with increasing temperature, which reflects the seasonality in emissions to water. This has an implication for the design of future monitoring programs aimed at assessment of long term trends. For such analysis time series should be constructed of data from samples collected always in the same season of the year.

Perfluoroalkyl Contaminants in Lake Ontario Lake Trout: Detailed Examination of Current Status and Long-Term Trends

Perfluoroalkyl contaminants (PFCs) were determined in Lake Ontario Lake Trout sampled annually between 1997 and 2008 in order to assess how current trends are responding to recent regulatory bans and voluntary phase-outs. We also combined our measurements with those of a previous study to provide an updated assessment of long-term trends. Concentrations of PFCs generally increased from the late 1970s until the mid-1980s to mid-1990s, after which concentrations either remained unchanged (perfluorooctane sulfonate (PFOS) and perfluorocarboxylates) or declined (perfluorodecanesulfonate (PFDS)). The temporal trends were assessed using three models, quadratic, exponential rise to maximum, and two-segment linear piecewise function, and then evaluated for best fit using Akaike Information Criteria. For PFOS and perfluorocarboxylates, the exponential rise to maximum function had the best fit. This is particularly interesting for PFOS as it suggests that although concentrations in Lake Ontario Lake Trout may have stopped increasing in response to voluntary phase-outs in 2000-2002, declines have yet to be observed. This may be due to continuing input of PFOS from products still in use and/or slow degradation of larger precursor molecules. A power analysis of PFOS suggested that 15 years of data with a within-year sample size of 10 is required to obtain sufficient power (80%) to detect a 5% decreasing trend. However, the length of the monitoring program had a greater influence on the ability to detect a trend compared to within-year sample size. This provides evidence that additional sampling years are required to detect a response to bans and phase-outs, given the variability in the fish data. The lack of observed declines of perfluorocarboxylate residues in fish may be expected as regulations for these compounds were only recently enacted. In contrast to the other compounds, the quadratic model had the best fit for PFDS. The results of this study emphasize the importance of long-term monitoring for assessing the effectiveness of bans and phase-outs on PFCs in the environment.

An assessment of long-term trends in hydrologic components and implications for water levels in Lake Superior

The combination of climate change and natural periodicities in meteorological variables are demonstrating significant impacts on the water resources of Lake Superior within the Laurentian Great Lakes system of North America. Statistical analyses of long-term records are used to demonstrate how changes over time may be interpreted very differently, depending upon the timeframe over which the analyses are made. Non-linear regression modelling shows that, while increasing trends in overland and overlake precipitation, flows and runoff occurred during the first decades of the twentieth century, very different trends are apparent for the period 1970–2005. For this latter period, increasing rates of air overlake temperature and lake evaporation are occurring but all other parameters are demonstrating decreasing trends. The result is a decline in water levels in Lake Superior at the rate of approximately 1 cm per year over the last 35 years. The results are used to show that to avoid decreasing water levels in Lake Superior, the discharge through St Mary's River must be decreased to approximately one-half the long-term annual average, the results of which will have dramatic implications for ships' cargo levels and hydroelectric energy generation.

Can pine needles indicate trends in the air pollution levels at remote sites?

Data from ten years of integrated monitoring were used here to evaluate whether pine needles are a feasible tool for an assessment of long-term trends of the atmospheric contamination. Pine needles collected once a year were compared to high volume air samples collected for 24 h, every 7 days, and passive air samples integrated over 28-day periods. Results showed the same concentration patterns of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) captured in needles and high volume samples. Passive air samplers were less efficient in sampling the particle-bound compounds. Theoretical air volume equivalent to each needle sample (V EQ) was calculated as a ratio of the needle concentration over the mean air concentration. Results indicated different equivalent volumes for PAHs and organochlorines, possibly due to the faster degradation rates of PAHs in needles. The most important finding is that in the long term a needle monitoring gives very similar information on temporal trends of the atmospheric pollution as does a high volume air monitoring.

Assessment of Long-term Trends in the Oxygen Resources of a Recovering Urban Lake, Onondaga Lake, New York

Long-term trends in dissolved oxygen (DO) resources are documented for ionically enriched, hypereutrophic Onondaga Lake, New York, for 1978–2002. Assessments of oxygen resources are based on DO profiles of 1 m resolution conducted hourly to weekly during April-October. Closure of an industry that operated on the lake's shore until 1986 resulted in an abrupt decrease in primary production and organic carbon deposition and marked changes in hypolimnetic and epilimnetic DO regimes. The hypolimnetic DO response was gradual, reflecting the influence of sediment feedback. The onset of complete hypolimnetic anoxia, which occurred by early June through the 1980s, took place approximately one month later over 1997–2002. The anoxic factor decreased significantly over the study interval, from 97±5 d to 67±2 d. Epilimnetic DO concentrations responded rapidly to the abrupt change in lake metabolism. Before closure of the industry, 41% of the April to mid-September DO observations deviated from saturation concentrations by >30%. In the years immediately following industry closure, this degree of disequilibrium occurred in 23% of DO observations. Percent saturation values during fall turnover increased gradually during the study, from 49±2 to 65±2. DO concentrations in the lake's upper waters have been subject to substantial diel fluctuations (>4 mg/L), with daily minima and maxima generally occurring at approximately 7:00 and 16:00, respectively. Measurements made at 11:00 and 22:00 were most likely to be representative of daily average conditions. Diel variations and sampling frequency were demonstrated to be important issues for the evaluation of status with respect to water quality standards for DO. Levels of DO in the lake's upper waters have been positively correlated with chlorophyll a concentrations (r = 0.52). Despite marked improvements in DO resources, the lake continues to lack cool, well-oxygenated waters during summer necessary to support coldwater fish species.

A new definition for myocardial infarction: what difference does it make?

As a response to changing diagnostic tools of myocardial infarction (MI), new case definitions for acute coronary events were published in 2003 as the American Heart Association Scientific Statement. We assessed the new definition in hospitalized patients in a large population-based MI register study. We identified all suspected acute coronary syndromes with data either on troponin T or on troponin I and at least one of the enzymatic markers of myocardial injury (n=6104). The 2003 definition with the use of troponins identified 83% more definite MIs than the WHO MONICA definition using cardiac enzymes. The additional patients were older, had more often diabetes, and received less often thrombolysis and revascularization than those having MI by both definitions. Adjusting for age, sex, study area, and study year, the additional patients with their first MI aged 25-74 had a higher risk of cardiovascular death within 1 year than patients having definite MI by both definitions (hazard ratio 1.6, 95% CI 1.1-2.2). The changing diagnostic criteria present a considerable challenge for the assessment of long-term trends in MI events in the community as well as for longitudinal studies of the natural history of MI. The 2003 definition, when applied using troponins, identified a sizable new group of MI patients, among persons with suspected acute coronary syndrome, at high risk of a recurrent event.

Housing Outcomes: An Assessment of Long-Term Trends

The main conclusions drawn from the authors' analysis are as follows. There has been significant improvement in the physical adequacy of the housing stock over the past few decades, particularly for households in the lowest income quintile. As a result, today there is very little difference across income quintiles in terms of the physical adequacy of the units occupied. A similar result holds for persons per room. Because newly constructed housing units have tended to increase in size over time while the number of persons per household has declined, persons per room has steadily declined for all income quintiles and there is now little difference across them. Assessments of neighborhood quality have also improved, although not nearly as much as the physical quality of the housing stock, and a sharp divergence of assessments of neighborhood quality remains across the income quintiles. In contrast, financial commitment has not improved, particularly for lower income households. The share of this group's income devoted to housing increased significantly in the late 1970s (a period of rapid inflation) and remained high in the 1980s (a period of generally high interest rates). While there has been some improvement for the population as a whole in the 1990s - likely due in part to the slowing of inflation and the associated drop in long-term interest rates - this improvement has not been experienced by households in the lowest income quintile.

Specimen banking at National Institute for Environmental Studies, Japan

The National Institute for Environmental Studies (NIES) in Japan has had more than fifteen years practical experience in specimen banking. Stored specimens are used for the assessment of long-term trends of pollutants. The use of new analytical techniques facilitates the finding of the pollutants of the past.

Monitoring Breeding Bird Populations in Grand Teton National Park: 1995-1997

In summer 1997 our NPS-funded project # CA-1460-5-0010, covering a 3-y period from summer 1995 through summer 1997, was completed. The immediate goals of the project were to instigate a system for monitoring the densities of breeding bird species, by establishment of flxed sites as a basis for a long term monitoring plan and of census protocols that can detect changes of breeding species and their densities over successive years. The monitoring scheme is conducted largely within Grand Teton National Park (GTNP), but covers habitats and an avifauna representative of the Greater Yellowstone Ecosystem (GYE) and the central-northern Rocky Mountains in general. The project emphasizes the need for long­term and on-going studies on breeding bird species and densities and their importance as a tool for evaluating the impact of both local and distant influences on breeding bird populations. For residents, species that remain all year in or near the breeding habitat, local effects include those operating on-site during the non-breeding season as well as during the breeding season. For migrant species, those that breed on-site but leave to spend the non-breeding season in other locations, often distant and usually of quite different habitat composition, there are both on-site influences on breeding population densities, such as inter-year changes in vegetation structure and productivity, and off-site or distant influences, including factors that affect over-wintering success in the non­breeding habitat and others that influence a successful transit between wintering and breeding grounds. The assessment of long-term trends in bird densities may be used as a form of bioassay of the state of the local environments. Information from such studies can provide region-wide indicators that, given a sufficiently comprehensive data base, can segregate local from distant influences on populations. Such indicators can be incorporated into management strategies to aid in determining which local strategies may be necessary (and feasible) to help maintain the biota.

Monitoring and modeling of coastal waters in support of environmental preservation

The improved monitoring and modeling capability resulting from recent technological advances in oceanographic sensors, computer processing power, and telecommunications can play a major role in environmental preservation. In particular, this capability can help improve: safe navigation and thus the prevention of maritime accidents that lead to hazardous spills; the effective cleanup of hazardous spills when they do occur; the real-time assessment of water quality problems; the assessment of long-term trends and variability due to both anthropogenic and climate change effects; and the understanding of key physical, chemical, and ecological processes.

The suitability of a single intertidal fish trap for the assessment of long-term trends in fish and epibenthic invertebrate populations

The suitability of a single intertidal fish trap for the assessment of long-term trends in fish and epibenthic invertebrate relies upon the assumption of an on-average constant sampling fraction from the study population. This assumption was examined by comparing trends over years in five different traps within the study area. For some species, like cod, the traps showed more or less parallel fluctuations. This is in agreement with the assumption. However, for other species, like mackerel, the assumption was invalidated by distinct trends over years.

Total Phosphorus and Dissolved Oxygen Trends in the Central Basin of Lake Erie, 1970–1991

Five yearly estimators of total phosphorus (TP) concentrations in the central basin of Lake Erie from 1970 to 1986 were calculated and compared to evaluate their utility in the assessment of long term trends. Data were selected from stations within a defined polygon for those years in which at least four surveys were conducted, including spring and fall isothermal conditions and at least two surveys during stratification. Included were an arithmetic average of all survey means during each year, a time-weighted average of all survey means, a spring (isothermal) average, a summer (stratified) average, and an autumn (isothermal) average. The rate of decline in TP concentrations from the spring-only estimator (−0.276 μg TP L -1 yr -1) was similar to that of the time-weighted multiple survey estimator (−0.214 μg TP L -1 yr -1). Additional spring survey data from 1987 through 1991 confirmed that the negative trend continued. The stratified season and the autumn-only estimators exhibited no significant trends, but were biased low and high, respectively, relative to the spring and multiple survey estimators. Despite the reductions in TP concentrations since 1970, the annual normalized rate of oxygen depletion in the hypolimnion of the central basin showed only a slight downward trend (-0.03 mg L -1 mo -1). In 1988 and 1989, however, the depletion rates were lower than any reported during the previous 20 years.

The FINMONICA Stroke Register. Community-based stroke registration and analysis of stroke incidence in Finland, 1983-1985.

In the early 1980s, a standardized community-based stroke register was started in three geographic areas in Finland: North Karelia and Kuopio in eastern Finland and Turku/Loimaa in southwestern Finland. The results from the first 3 years, 1983-1985, confirmed the high incidence of stroke in Finland. The incidence of stroke was higher in eastern Finland than in the southwestern part of the country. The age-standardized annual incidence among men aged 25-74 years varied from 206 per 100,000 population in southwestern Finland to 322 per 100,000 population in the province of Kuopio in eastern Finland. Among women aged 25-74, incidence was 119 and 187 per 100,000 population in these two areas, respectively. The age-standardized male:female ratio in incidence was 1.7, slightly higher than that previously reported in Finland. Out of 3,574 stroke events registered, 78% were first events without a history of previous stroke. People aged 65-74 years accounted for 45% of all events among men and 62% of all events among women. The authors' experience shows that the geographic variation in stroke incidence and attack rates is difficult to assess even within a country with a relatively uniform health care system. Rigorous standardization and quality control is needed for the assessment of long-term trends; this is the primary goal of the FINMONICA Stroke Register. The findings of this study suggest that the incidence of stroke is still high in Finland, although mortality from stroke has steeply declined during the past 15-20 years. The number of stroke survivors in Finland may actually be increasing. Since the occurrence of stroke is high in Finland as compared with other countries, intensified primary and secondary prevention measures are needed to reduce it.