首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
In the first study on this scale, distribution and transport of selected hydrophobic halogenated organic compounds associated with suspended sediment from the lower Mississippi River and its principal tributaries were determined during two spring and two summer cruises. Lipophilic organic compounds identified on the suspended sediment included hexachlorobenzene, pentachlorobenzene, pentachloroanisole, dacthal, chlordane (cis- and trans-), nonachlor (trans-), chlorthalonil, and penta-, hexa-, hepta-, and octachlorobiphenyls. Most of these compounds come from nonpoint sources. Mass loadings of most of the compounds increased from upstream to downstream on the main stem of the Mississippi River. Of the tributaries studied, the Ohio River had the most significant effect on contaminant loads. Suspended sediment transport to the Gulf of Mexico of the most abundant, widely distributed compound class, PCBs, was estimated at 6,750 kg per year. Received: 9 April 1998/Accepted: 28 October 1998  相似文献   

2.
3.
Spatio-temporal variations in sediment quality (20 sample sites) of the Ebro River basin between 2001 and 2011 have been assessed. The self-organizing map classified the sediment samples according to similarities in their chemical compositions. Its powerful visualization tools helped establish the main pollution contribution on each sample. Most of the samples showed low values of the mean-probable effect concentration quotient through time. However, six samples presented several quality issues related to some trace elements or polycyclic aromatic hydrocarbons. Finally, geoaccumulation index values calculated using estimates of background trace element concentrations suggested anthropogenic influences in more than half of the samples.  相似文献   

4.
5.
We determined levels of Se, As, Cd, Pb, and Zn in aquatic insects at coal mine–impacted and reference sites in streams in the Rocky Mountain foothills of west central Alberta from 2001–2003. Selenium levels were greater at coal mine–impacted sites than at reference sites in caddisflies but not in mayflies or stoneflies. Arsenic levels were greater at coal mine–impacted sites than at reference sites in caddisflies and stoneflies but not in mayflies. Zn levels were higher at coal mine–impacted sites than at reference sites in all three groups of insects. At coal mine–impacted sites, Se levels in mayflies and caddisflies were greater than those in stoneflies while at reference sites mayflies contained greater concentrations of Se than either caddisflies or stoneflies. Arsenic levels in mayflies were greater than those in caddisflies at reference and coal mine–impacted sites and were greater than those in stoneflies at reference sites. At both types of sites Cd differed amongst insect taxa in the order of mayflies > caddisflies > stoneflies. The same was true of Zn at coal mine–affected sites. At reference sites, stoneflies had greater concentrations of Zn than both mayflies and caddisflies. At both types of sites, Pb levels were greater in mayflies and caddisflies than they were in stoneflies. Of the five trace elements considered in this study, only Se was sufficiently elevated in aquatic invertebrates to be of potential concern for consumers such as fish and aquatic birds. Such was the case at both coal mine–impacted and reference sites.  相似文献   

6.
7.
Bulletin of Environmental Contamination and Toxicology -  相似文献   

8.
Solar radiation exposure can increase the toxicity of bioaccumulated oil compounds in a diversity of aquatic species. We investigated the photoenhanced toxicity of weathered South Louisiana crude oil in sediment and water accommodated fractions (WAF) to larval zebrafish. Larvae were first exposed for 24 h to one of six treatments: no oil (sediment or water), 7.5 g oil/kg sediment, oil-only WAF, oil WAF plus the dispersant Corexit 9500A, or dispersant alone. Larvae were then exposed to high or low levels of sunlight in control water for 3 or 3.5 h. Hydrocarbon concentrations were measured in exposure media, including alkanes, polycyclic aromatic compounds and total petroleum hydrocarbons. Significant phototoxicity was observed in larvae exposed to oiled sediment, oil-only WAF, and oil plus dispersant WAF. The results indicated that petroleum from the northern Gulf of Mexico can be phototoxic to larval fish exposed to oil in either the water column or sediment.  相似文献   

9.
The concentrations of iron, lead, cadmium, copper, manganese, mercury and arsenic were measured in water, sediment, five macrophytes (Typha angustifolia, Iris pseudacorus, Polygonum amphybium, Myriophyllum spicatum and Lemna gibba) and five fish species (Sander lucioperca, Abramis brama, Carassius gibelio, Silurus glanis and Arystichtys nobilis) in the Gru?a Reservoir, used for water supply and recreational fishing. The concentrations of all examined elements were higher in sediment than in water. The values of the ratio between element concentrations in the sediment and those in the water were the highest for Fe and As. Among the five plant species, the highest concentrations of Pb and Mn were observed in T. angustifolia, while the highest concentrations of Fe, Cu and Hg were in L. gibba. I. pseudacorus and P. amphybium had the highest concentrations of Cd and As, respectively. Among the fish species, C. gibelio showed the highest tendency of element accumulation (Fe, Cd, Cu), followed by S. lucioperca (Pb, Hg), A. brama (Mn) and A. nobilis (As). The average concentrations of elements in fish muscle, except for As in A. nobilis (2.635 ± 0.241 mg kg?1 ww), were below the limits that are considered safe for human consumption in accordance with the European Commission Regulation and Official Gazette of Serbia.  相似文献   

10.
The purpose of this article is to describe health conditions in a pan-mining community, in particular the interaction of mercury contamination with other health problems. This study was carried out in a panning mine located on Rato Creek, a tributary of the Tapajó s River Basin in the municipality of Itaituba, State of Par The study population consisted of 223 individuals. An epidemiological questionnaire was applied, medical treatment was given, and biological specimens were collected. Testing of fecal samples showed that 96.1% of the individuals had parasites and 66.4% were anemic. Prevalence of hepatitis B virus was 85.0%, and 11 individuals (6.0%) were virus carriers (HBsAg positive). Of 186 patients tested for malaria, 65 individuals (35.0%) had the infection, of whom 34 (52.3%) were asymptomatic. Prevalence of syphillis was 41.6%. Urine mercury levels were measured in 173 individuals. Some 16 (9.2%) of those tested had mercury levels between 10 and 19 ug/l, while 9 patients (5.2%) had levels above 20 ug/l. An overview of general health conditions showed a combination of problems in individuals, who lacked adequate diagnosis, in addition to a high level of self-medication, given the absence of health facilities. In addition, these individuals are threatened by critical levels of mercury contamination. In conclusion, this article gives a general overview of health conditions in these pan-mining communities, demonstrating the multicausal nature of health conditions in the Amazon region, a fact which should be considered when planning appropriate strategies for clinical treatment.  相似文献   

11.
12.
In a cross-sectional, panel study, we examined the relationship between state firearm laws and the extent of interstate transfer of guns, as measured by the percentage of crime guns recovered in a state and traced to an in-state source (as opposed to guns recovered in a state and traced to an out-of-state source). We used 2006–2016 data on state firearm laws obtained from a search of selected state statutes and 2006–2016 crime gun trace data from the Bureau of Alcohol, Tobacco, Firearms, and Explosives. We examined the relationship between state firearm laws and interstate transfer of guns using annual data from all 50 states during the period 2006–2016 and employing a two-way fixed effects model. The primary outcome variable was the percentage of crime guns recovered in a state that could be traced to an original point of purchase within that state as opposed to another state. The main exposure variables were eight specific state firearm laws pertaining to dealer licensing, sales restrictions, background checks, registration, prohibitors for firearm purchase, and straw purchase of guns. Four laws were independently associated with a significantly lower percentage of in-state guns: a waiting period for handgun purchase, permits required for firearm purchase, prohibition of firearm possession by people convicted of a violent misdemeanor, and a requirement for relinquishment of firearms when a person becomes disqualified from owning them. States with a higher number of gun laws had a lower percentage of traced guns to in-state dealers, with each increase of one in the total number of laws associated with a decrease of 1.6 percentage points in the proportion of recovered guns that were traced to an in-state as opposed to an out-of-state source. Based on an examination of the movement patterns of guns across states, the overall observed pattern of gun flow was out of states with weak gun laws and into states with strong gun laws. These findings indicate that certain state firearm laws are associated with a lower percentage of recovered crime guns being traced to an in-state source, suggesting reduced access to guns in states with those laws.  相似文献   

13.
14.
15.
16.
We investigate the geographic patterns of drug poisoning deaths involving heroin by county for the USA from 2000 to 2014. The county-level patterns of mortality are examined with respect to age-adjusted rates of death for different classes of urbanization and racial and ethnic groups, while rates based on raw counts of drug poisoning deaths involving heroin are estimated for different age groups and by gender. To account for possible underestimations in these rates due to small areas or small numbers, spatial empirical Baye’s estimation techniques have been used to smooth the rates of death and alleviate underestimation when analyzing spatial patterns for these different groups. The geographic pattern of poisoning deaths involving heroin has shifted from the west coast of the USA in the year 2000 to New England, the Mid-Atlantic region, and the Great Lakes and central Ohio Valley by 2014. The evolution over space and time of clusters of drug poisoning deaths involving heroin is confirmed through the SaTScan analysis. For this period, White males were found to be the most impacted population group overall; however, Blacks and Hispanics are highly impacted in counties where significant populations of these two groups reside. Our results show that while 35–54-year-olds were the most highly impacted age group by county from 2000 to 2010, by 2014, the trend had changed with an increasing number of counties experiencing higher death rates for individuals 25–34 years. The percentage of counties across the USA classified as large metro with deaths involving heroin is estimated to have decreased from approximately 73% in 2010 to just fewer than 56% in 2014, with a shift to small metro and non-metro counties. Understanding the geographic variations in impact on different population groups in the USA has become particularly necessary in light of the extreme increase in the use and misuse of street drugs including heroin and the subsequent rise in opioid-related deaths in the USA.  相似文献   

17.
Objectives India has more unvaccinated children than any other country despite provision of free vaccines through the government’s Universal Immunization Program. In this study, we calculated the proportion of children aged 12–48 months who were fully vaccinated, under-vaccinated, or who had not received any vaccines. Childhood, household, and sociocultural factors associated with under-vaccination and non-vaccination were evaluated. Methods Using data from India’s 4th District-level Health and Facility Survey, 2012–2013 (DLHS-4) and the 2012–2013 Annual Health Survey (AHS), we calculated the proportion of children who were non-vaccinated, under-vaccinated, or fully vaccinated with 1 dose of Bacillus Calmette–Guérin, 3 doses of oral polio vaccine, 3 doses of diphtheria–pertussis–tetanus, and 1 dose of measles-containing vaccine. The odds of full vaccination compared to non-vaccination and under-vaccination relative to various factors was assessed using a multivariable, multinomial logistic regression which accounted for survey design. Results Of 1,929,580 children aged 12–48 months, 59% were fully vaccinated, 34% were under-vaccinated, and 7% were non-vaccinated. Compared to children born in government institutions, children delivered in non-institutional settings with a skilled birth attendant present had higher odds of non-vaccination (OR 1.66) and those without a skilled attendant present had still greater odds of non-vaccination (OR 2.39) and under-vaccination (OR 1.11). Conclusions for Practice India’s vaccination rates among children aged 12–48 months remains unacceptably low. The Indian government should encourage institutional delivery or birthing with a skilled attendant to ensure women receive adequate health education through antenatal care that includes the importance of childhood vaccination.  相似文献   

18.
The Suquía River middle-lower basin (Córdoba, Argentina) is subject to a strong anthropogenic impact because it receives pollutants from different sources. Recent studies have shown the importance and the need of approaching the monitoring process of water quality from integral perspectives through the use of chemical as well as biological methods. The main goal of this study was to evaluate the fish species Jenynsia multidentata as a bioindicator of environmental pollution in the middle-lower basin of the Suquía River using biotransformation and antioxidant enzymes as well as gill and liver histopathology as biomarkers. We also studied the fish-assemblage characteristics through the fish species pattern variation and the application of a biotic index based on fish data. Our study also included the analysis of a water-quality index, heavy-metal concentrations in sediment and water, and pesticide concentrations in sediment. The chemical analyses of the middle-lower Suquía River basin showed a water-quality degradation gradient. Fish-assemblage structure changed with increasing water pollution, showing a simpler structure at the most polluted area. According to the bioitc index, the variation pattern of fish assemblages reflected the aquatic environmental deterioration. Both molecular and histopathological biomarkers reflected the same trend in relation to water quality. However, enzymes varied with more acute precision between seasons. In addition, each enzyme presented with different sensibility. At tissue level, the histopathological analysis detected chronic contamination at both stations and seasons. The present work, which comprises different levels of biological organization together with chemical analyses, generated particular although complementary information, thus evidencing the same trend of aquatic contamination. Thus, the development of integral investigations gives a comprehensive approach and becomes the most effective tool to construct policies both preventive and palliative. Our study constitutes a good model to be applied in other endorheic basins of South America.  相似文献   

19.
Bulletin of Environmental Contamination and Toxicology - Manure, soil, and vegetable samples were collected from different-sized livestock farms in Xinxiang, China. The residues of sulfadiazine,...  相似文献   

20.

Purpose

Our understanding of the temporal dynamics and age-specific mortality patterns of the 1918–1921 influenza pandemic remains scarce due to lack of detailed respiratory mortality datasets in the United States and abroad.

Methods

We manually retrieved individual death records from Arizona during 1915–1921 and applied time series models to estimate the age specific mortality burden of the 1918–1921 influenza pandemic. We estimated influenza-related excess mortality rates and mortality rate ratio increase over baseline based on pneumonia and influenza (P&I), respiratory, tuberculosis and all-cause death categories.

Results

Based on our analysis of 35,151 individual mortality records from Arizona, we identified three successive pandemic waves in spring 1918, fall 1918–winter 1919 and winter 1920. The pandemic associated excess mortality rates per 10,000 population in Arizona was estimated at 83 for P&I, 86 for respiratory causes, 84 for all-causes and 9 for tuberculosis. Age-specific P&I and tuberculosis excess death rates were highest among 25- to 44-year-olds and individuals ≥65 years, respectively. The 25- to 44-year-olds and 5- to 14-year-olds had highest P&I and tuberculosis mortality impact respectively when considering the ratio over background mortality.

Conclusions

The 1918–1921 influenza pandemic killed an estimated 0.8% of the Arizona population in three closely spaced consecutive waves. The mortality impact of the fall 1918 wave in Arizona lies in the upper range of previous estimates reported for other US settings and Europe, with a telltale age distribution of deaths concentrated among young adults. We identified a significant rise in tuberculosis-related mortality during the pandemic, lending support to the hypothesis that tuberculosis was a risk factor for severe pandemic infection. Our findings add to our current understanding of the mortality impact of this pandemic in the US and globally.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号