Historical trends in teacher personality from human language.

Understanding the historical perception and value of teacher personalities reveals key educational priorities and societal expectations. This study analyzes the evolution of teachers' ascribed Big Five personality traits from 1800 to 2019, drawing on millions of English-language books. Word frequency analysis reveals that conscientiousness is the most frequently discussed trait, followed by agreeableness, openness, extraversion, and neuroticism. This pattern underscores society's focus on whether teachers are responsible. Polarity analysis further indicates a higher prevalence of low neuroticism descriptors (e.g., patient and tolerant) in descriptions of teachers compared to the general population, reinforcing the perception of teachers as stable and dependable. The frequent use of terms like "moral", "enthusiastic", and "practical" in describing teachers highlights the positive portrayal of their personalities. However, since the mid-20th century, there has been a notable rise in negative descriptors related to openness (e.g., traditional and conventional), coupled with a decline in positive openness terms. This shift suggests an evolving view of teachers as less receptive to new ideas. These findings offer valuable insights into the historical portrayal and societal values attributed to teacher personalities.

The urban in ecology: a quantitative textual analysis of the scientific literature over a century.

Many authors have described 'urban ecology' as a subfield of ecology that emerged in the 1990s and has expanded exponentially. We propose to take a step further and analyse the expansion of the 'urban' in ecology with a novel quantitative approach, with the aim to better understand the relationship between ecology and the urban. Previous quantitative assessments of the urban in ecology have focused on short to medium time spans (5 to 40 years) and on research coined as 'urban ecology', and have rarely considered the content of publications (e.g., vocabulary and topics) using quantitative methods. In this paper, we conduct a bibliometric assessment and an in-depth quantitative textual data analysis of a corpus of 960 articles published from 1922 to 2018 in 10 leading English-language journals in ecology and conservation biology. We address the following questions: (1) When and how have urban environments been integrated into ecological research during the past century? (2) What urban research topics have been investigated in ecology during the same period? (3) How have these research topics changed through time? Our results show that the urban was never entirely absent from publications in ecology. The quantitative analyses highlight three turning points (1970s, 1990s and 2000s) in the relationship between ecology and the urban. Moreover, they help visualize the shift from particularly scattered publications at the beginning of the period to publications characterized by a more homogeneous vocabulary, reflecting the stabilization of a research field focused on the urban in ecology. Supplementary Information: The online version contains supplementary material available at 10.1007/s11252-024-01603-4.

Historical trends of metals concentration in PM10 collected in the Mexico City metropolitan area between 2004 and 2014.

In this work, we report metals concentrations in 80 PM10 samples collected at four sites in the Mexico City Metropolitan Area (MCMA): Tlalnepantla (NE), Xalostoc (NE), Merced (C), and Pedregal (S), during the dry/cold season (October to January) for the 2004-2014 period. Mean PM10 mass concentration (66.1 µg m-3) significantly exceeds the annual mean air quality guidelines recommended by the World Health Organization. The statistical analysis of concentration data and meteorological parameters allows us to recognize the importance of wind intensity speed (Wsp) and wind direction conditions in the enrichment of PM concentrations. The proximity and magnitude of the emitting source is also relevant for PM concentration. Such conditions favored that higher metal concentration was recognized at the north of the studied area. By means principal component analysis (PCA) was difficult to identify the groups of metals associated with specific sources (anthropogenic and geogenic) given the high complexity of the study area and the long period of time evaluated. Metal concentration trend shows an important positive trend for Pt, V and Cr, while PM10, Ni, Cu, Ag and Sb show a trend of moderate increase. In contrast, Pb and Co registered a strong percentage reduction, while Hg, Mn, As and Cd show a slight reduction, probably resulting from the implementation of regulatory measures and influenced by urban changes associated at the north of the studied area. The results of this research provide information that should be considered for evaluating the impact of anthropogenic sources and applying regulatory measures to control emissions.

Historical trends of PCBs and PBDEs as reconstructed in a lake sediment from southern Tibetan Plateau.

High-altitude lake sediment can be used as a natural archive to reconstruct the history of pollutants. In this work, the temporal distribution of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined using a high-resolution gas chromatography coupled with high-resolution mass spectrometer (HRGC/HRMS) in an alpine lake sediment core collected from the southern Tibetan Plateau (TP) to examine whether the expected decreasing trends due to the implementation of the international Conventions could be observed. The concentrations of PCBs and PBDEs in the sediment core were in the range of 11.8-142 pg/g dw and ND-457 pg/g dw, and their fluxes were in the range of 2.51-31.7 ng/(m2·yr) and ND-43.2 ng/(m2·yr), respectively. The prevalence of low-chlorinated (tri-CB) PCBs and low-brominated (tri- to tetra-) PBDEs in most sections of the sediment profiles was observed, suggesting that the light molecular weight PCBs and PBDEs have most likely reached lake sediments by long-range atmospheric transport from distant sources. Despite the restrictions on their applications, the sediment records for the concentrations and fluxes showed no corresponding decreasing trend with restrictions for PCBs, which suggested that these POPs (e.g., PCBs) were still emitted to the environment owing to the influence of primary or secondary emissions. To our knowledge, this is the first report on input history of atmospheric PCBs and PBDEs recorded in TP Lake sediment.

Feasibility of analyzing DNA copy number variation in breast cancer tumor specimens from 1950 to 2010: how old is too old?

PURPOSE: The purpose of the study was to assess the feasibility of quantifying long-term trends in breast tumor DNA copy number variation (CNV) profiles. METHODS: We evaluated CNV profiles in formalin-fixed paraffin-embedded (FFPE) tumor specimens from 30 randomly selected Kaiser Permanente Northern California health plan women members diagnosed with breast cancer from 1950 to 2010. Assays were conducted for five cases per decade who had available tumor blocks and pathology reports. RESULTS: As compared to the tumors from the 1970s to 2000s, the older tumors dating back to the 1950s and 1960s were much more likely to (1) fail quality control, and (2) have fewer CNV events (average 23 and 31 vs. 58 to 69), fewer CNV genes (average 5.1 and 3.7k vs. 8.1 to 10.3k), shorter CNV length (average 2,440 and 3,300k vs. 5,740 to 9,280k), fewer high frequency Del genes (37 and 25% vs. 54 to 76%), and fewer high frequency high_Amp genes (20% vs. 56 to 73%). On average, assay interpretation took an extra 60 min/specimen for cases from the 1960s versus 20 min/specimen for the most recent tumors. CONCLUSIONS: Assays conducted in the mid-2010s for CNVs may be feasible for FFPE tumor specimens dating back to the 1980s, but less feasible for older specimens.

Historical record of anthropogenic polycyclic aromatic hydrocarbons in a lake sediment from the southern Tibetan Plateau.

High-altitude lake sediments can be used as natural archives to reconstruct the history of pollutants. In this work, the temporal distribution of polycyclic aromatic hydrocarbons (PAHs) was determined in a sediment core collected from the southern Tibetan Plateau (TP), which was dated by using the 210Pb dating method and validated with the 137Cs fallout peak. The concentrations of the anthropogenic PAHs (Σ8PAH) in the sediment core ranged from 0.83 to 12 ng/g dw, and the fluxes of the Σ8PAH were in the range of 2.1-27 g/cm2/year. The temporal variations in the concentration and input flux of anthropogenic PAHs were low with little variability before the 1950s, and then gradually increased from the 1950s to the 1980s, and an accelerated increase was observed after the early 1980s. The content of total organic carbon played an insignificant role in affecting the time trends of PAHs in the sediment core. Diagnostic concentration fractions of PAH components indicate PAHs in the lake sediment of the southern TP which are mainly from biomass burning and/or from long-range atmospheric transport.

Historical trends of organochlorine pesticides (OCPs) recorded in sediments across the Tibetan Plateau.

Sediment cores from four lakes across the Tibetan Plateau were used as natural archives to study the time trends of organochlorine pesticides (OCPs). The total concentrations of dichlorodiphenyltrichloroethane (ΣDDT) and hexachlorocyclohexane isomers (ΣHCH) were in the range of 0.04-1.61 and 0.08-1.88 ng/g based on dry weight (dw), while the input fluxes were in the range of 0.3-236 and 0.7-295 pg/cm2/y in the core sediments, respectively. The input fluxes of ΣDDT and ΣHCH generally peaked in sediment layers corresponding to the 1970s-1990s and peaked in top sediment layers. The ratio of α/γ-HCH decreased in the top layer sediments, implying that the contribution of lindane (pure γ-HCH) has been increasing in recent years. In addition, the ratio of o,p'-DDT/p,p'-DDT increased significantly over the last 15-20 years, suggesting that dicofol (characterized by high ratio of o,p'-DDT/p,p'-DDT about 7.0) has recently become a relatively more important source of DDT compared to technical DDT itself. The time trends of OCPs recorded in lake sediments examined the impact on such remote alpine regions by human activities.

Age-Specific Prevalence of Binge and High-Intensity Drinking Among U.S. Young Adults: Changes from 2005 to 2015.

BACKGROUND: This study examined changes during the past decade, from 2005 to 2015, in binge and high-intensity drinking in 7 separate age groups of U.S. 12th graders and young adults. METHODS: National longitudinal data (N = 6,711) from Monitoring the Future were used to examine trends in consuming 5+, 10+, and 15+ drinks on the same occasion in the past 2 weeks from ages 18 to 29/30 overall and by gender. Results were compared with trends in past 12-month and 30-day alcohol use for the same age groups. RESULTS: Between 2005 and 2015, binge (5+) and high-intensity drinking (10+, 15+) generally decreased for individuals in their early 20s, remained somewhat stable for individuals in their mid-20s, and increased for individuals at the end of young adulthood (age 29/30). The observed historical trends in binge and high-intensity drinking were similar to those for past 12-month and past 30-day alcohol use for those aged 18 to 20, but diverged for most other age groups in young adulthood. Trends were generally similar for men and women, except that the increase in prevalence began earlier in young adulthood for women than for men. CONCLUSIONS: Binge and high-intensity drinking among U.S. 12th graders and young adults are dynamic phenomena. Prevention and intervention efforts aimed at reducing the harms resulting from 5+, 10+, and 15+ drinking should acknowledge and focus on differences in trends in these behaviors by age and gender.

Air quality trends and implications pre and post Covid-19 restrictions.

Air pollution causes millions of premature deaths every year. Thus, air quality assessment is essential to preserve human health and support authorities to identify proper policies. In this study, concentration levels of 6 air contaminants (benzene, carbon monoxide, nitrogen dioxide, ground level ozone, particulate matters) as monitored in 2019, 2020 and 2021 by 37 stations, located in Campania (Italy) were analysed. Particular attention has been paid to March-April 2020 period to get clues on the possible effects of the lockdown regulations, imposed in Italy from March 9th to May 4th to limit COVID-19 spread, on atmospheric pollution. Air Quality Index (AQI), an algorithm developed by the United States Environmental Protection Agency (US-EPA), allowed us to classify the air quality from moderately unhealthy to good for sensitive groups. The evaluation of air pollution impact on human health by using the AirQ+ software evidenced a significant decrement of adult mortality in 2020 respect to 2019 and 2021. Among the six pollutants considered, PM10 and PM2.5 resulted the less affected by the lockdown restrictions. Finally, a comparison between NO2 ground level concentration and the reprocessed Level 2 NO2 tropospheric column concentration obtained from satellite surveys highlighted as concentration measured at the ground level stations can be strongly influenced by the station position and its surroundings.

The timing and magnitude of anthropogenic mercury pollution: A 200-year record from multi-lake sediment cores in northeast China.

The recent substantial expansion of human activities in northeast (NE) China has resulted in increased emission of environmental pollutants. Longer-term records of such environmental pollutants provide a benchmark against which it is possible to evaluate the nature, extent and timing of anthropogenic environmental changes. Based on measurements of mercury (Hg) concentrations and accumulation rates in 11 lake sediment cores from the Songnen Plain in NE China, we here present a reconstruction of the historical deposition of Hg as an indicator of the changing scale of human impact. The results demonstrate an increasing trend of Hg concentration, concurrent with elevated anthropogenic emissions, beginning from the early 1900s, accelerating through the mid-1950s and slightly decreasing from the late 1990s onwards. The increase in anthropogenic Hg coincides with the reform and opening up of China, which precipitated social and economic transformation, and rapid industrial and economic growth. Measurements of the Hg enrichment factor in all the cores enables identification of the anthropogenic contribution to Hg accumulation. The geoaccumulation index indicates that the lakes are in general moderately polluted by Hg. The historical trend of Hg accumulation rate parallels the temporal progression of biomass burning and fossil fuel consumption in the region. The findings elucidate the extent of anthropogenic pollution in the Anthropocene and underline the importance of identifying Hg sources to reduce emissions and guide the implementation of effective mitigation strategies.

More Bored Today Than Yesterday? National Trends in Adolescent Boredom From 2008 to 2017.

PURPOSE: Boredom is an accepted part of adolescence. Developmental and contextual factors are likely to conspire to increase boredom during adolescence, which, in turn, relates to health risk behaviors. However, literature is lacking in the developmental course of boredom across adolescence as well as historical variation in boredom. The present study used multicohort nationally representative samples of U.S. secondary school students to identify historical trends and grade level differences in boredom overall and by sex. METHODS: The present study includes 8th, 10th, and 12th graders from 2008 to 2017 who completed the Monitoring the Future self-report survey (n = 106,784). Joinpoint was used to identify historical trends in boredom and linear regression to identify grade level differences. RESULTS: Boredom increased historically both across and within grades with girls generally demonstrating greater increases than boys. Across grade, boredom appears to peak in 10th grade for boys and decrease across grade for girls. CONCLUSIONS: Study findings indicate boredom has been increasing among adolescents over the past several years, with greater increases among girls. Increases may be concomitant with recent increases in mental health difficulties, suggesting that the overarching psychosocial profile of U.S. adolescents is becoming less optimal. Findings also suggest boredom peaks in 10th grade overall although when analyzing separately by sex, girls' boredom declines from 8th to 12th grade. It is clear that boredom is a worthy target for intervention both in clinical and prevention contexts.

Occurrence and distribution of organophosphate esters in sediment from northern Chinese coastal waters.

Organophosphate esters (OPEs) are used as flame retardants and plasticizers in many consumer products. Owing to OPEs' toxicity, exposure of organisms in aquatic ecosystems is a concern. Information that pertains to the occurrence and distribution of OPEs in marine aquatic environment, however, is scarce. In this study, concentrations and profiles of 14 OPE triesters were determined in sediment collected in coastal waters (Bohai Sea and East China Sea) of northern China. The total concentrations of OPEs (ΣOPEs) in surface sediment were in the range of 1.76-49.9 (median: 9.13) ng/g dry weight (dw), which were comparable to or lower than the range of concentrations reported for surface sediments worldwide. Tris(2-chloro-propyl) phosphate (TCIPP), tris(2-chloroethyl) phosphate (TCEP), tri-isobutyl phosphate (TiBP), and tri-n-butyl phosphate (TnBP) were the predominant OPEs found in surface sediment, collectively accounting for 81% of the total concentrations. ΣOPE concentrations in sediment core (range: 8.58-169, median: 31.6 ng/g dw) were generally higher than those found in surface sediment. The vertical distribution of OPEs in sediment core showed a gradual increasing trend in concentrations during the past decade.

Centennial records of cadmium and lead in NE China lake sediments.

Cores (15 to 40 cm of depth) were collected from 11 lakes of the Songnen Plain in northeastern China to reconstruct changes in potentially harmful trace element (PHTE) inputs as tracers of human activities. In each profile, most PHTE enrichment factors do not differ significantly from the pre-industrial values (EF < 1.5), except for Cd (EF = 2-5.5). This shows that detrital material accounts for a large part of the PHTE supply to the Songnen Plain lakes. Radiometric dating of the cores (210Pb, 137Cs) showed that Cd contamination started from the mid-20th century and sharply increased in the 1980s', a pattern that matches the rapid economic and industrial growth of China. Comparison with other records in China suggests that a large part of the anthropogenic Cd in these lakes is likely local in origin. Although the Cd inputs, controlled by carbonate minerals, probably originated from a combination of sources, an intensification in agricultural practices, through the use of chemical fertilizers, manure and wastewater would explain these discrepancies between records. These findings highlight the importance of local factors on the Cd geochemical cycle in China. The large anthropogenic component of the Cd inventory compared to other PHTEs (Cu, Ni, Pb, Sb, V, Zn) and its high toxicity indicate that it should be prioritized in future environmental management.

[Historical Trends of Atmospheric Pb and Hg Emissions from Fossil Fuel Combustion in Shanghai].

Rapid urbanization in Shanghai over the past century has led to increased resource and energy consumption, in turn leading to the release of significant amounts of toxic pollutants into the urban environment. In order to investigate historical variations in atmospheric metal emissions from typical combustion sources in Shanghai, historical emissions of Pb and Hg from coal-fired sectors (coal-fired power plant, industrial sector, and domestic use) and vehicle exhaust in Shanghai during the period 1949-2015 were estimated, based on consumption of fossil fuels (coal and gasoline) and emission factors. Results showed that Pb and Hg emissions exhibited rapidly fluctuating increases from 1949 to the 1980s or 1990s, before beginning to decrease sharply due to various pollution control measures. Hg emissions from coal-fired sources played a dominant role during the 1980-2015 period, contributing a high proportion (87.5%-99.7%) to the total. The dominant sources of atmospheric Pb emissions have experienced historical variations. Coal-fired emissions became the major contributor (78.2%-83.5% of total) following omission of leaded gasoline from the Shanghai market since 1997. However, the rapid increase of gasoline consumption since 2005 has led to gasoline-fired emissions again becoming the main contributor (55.5%-79.1%).

Historical trends of anthropogenic metals in sediments of Jiaozhou Bay over the last century.

Reconstructing heavy metal historical trends are essential for better understanding anthropogenic impact on marine ecosystems. In this work, the ecological risk and sources of Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb in Jiaozhou Bay were studied and the anthropogenic metal emissions was also quantified. The ecological risk was mainly caused by Cd, As and Cu, which presented an increasing trend with increased anthropogenic activities since the 1950s. The statistical analysis show that Cr, Mn, Ni, Cu and Zn were primarily from natural sources. Cadmium and Mn might originate from both natural and anthropogenic sources. Arsenic and Pb were sourced from agricultural activities and atmospheric precipitation, respectively. The anthropogenic flux of Cr, Mn, Ni, Cu, Zn, As, Cd and Pb were 138, 586, 63, 66, 161, 35, 0.31 and 44 mg/m2/a since the 1950s. Over 40.0% of Cu and As were quantified from anthropogenic emissions since the 1950s.

Spatio-temporal trends of polybrominated dibenzo-p-dioxins and dibenzofurans in archived sediments from Tokyo Bay, Japan.

The present study examined the occurrence and potential sources of mono- to octa-brominated dibenzo-p-dioxins/dibenzofurans (Mo-OBDD/Fs) in Tokyo Bay, Japan, using surface sediments and 210Pb-dated sediment cores (covering the period 1895-2000) collected in 2002. The results showed a clear difference in the spatio-temporal trend between PBDFs and PBDDs. The spatial distribution of PBDF concentrations in the surface sediments showed a decreasing trend from the head to the mouth of the bay, which was similar to that of polybrominated diphenyl ethers (PBDEs) reported previously for the same sediment samples. In the sediment cores, PBDF and PBDE concentrations increased drastically after the 1960s and reached the highest levels in the late 1990s. In addition, a significant positive correlation was observed between the concentrations of their predominant congeners, 1,2,3,4,6,7,8-HpBDF and BDE-209. These results indicate that main contamination sources of PBDFs were technical PBDE formulations, especially DecaBDE. In contrast, total PBDDs in the surface sediments were rather uniform in the whole area of the bay. Furthermore, in the sediment cores, PBDD levels showed marginal fluctuation over the past century, with the predominance of 2,7-/2,8-DiBDDs and 1,3,7-/1,3,8-TrBDDs in all the sediment layers. It is noteworthy that these PBDD congeners were also found in the sediment layers corresponding to the pre-industrial era, supporting their natural formation in the coastal environment.

Occurrence, spatial distribution, historical trend and ecological risk of phthalate esters in the Jiulong River, Southeast China.

The occurrence and spatial distribution of phthalate esters (PAEs) in the Jiulong River of southeast China were investigated in water and sediment samples collected from 35 stations along the river in Mar. 2014. The historical trend of the past 26years was reconstructed with a sediment core collected in Dec. 2012 via a 210Pb dating technique. The potential ecological risk of PAEs was assessed using the risk quotient (RQ) method. Of the 16 PAE congeners analyzed, only 6 PAEs, including dimethyl phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), di-n-butyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP), were identified and quantified; the remaining 10 PAEs were below their respective limits of quantification (LOQs) for the analytical methods used here. The cumulative concentration of 6 PAEs (∑6PAEs) found in the samples spanned a range of 3.48-17.7µg/L in water and 0.046-1.65mg/kg in sediment. The most abundant PAEs in the water-phase were DEHP and DIBP, together accounting for 84.9% of ∑6PAEs in the North River, 82.8% of ∑6PAEs in the West River and 91.6% of ∑6PAEs in the estuary. DEHP and DINP were the richest congeners in the sediment-phase, with proportions of 84.9% in the North River, 81.0% in the West River and 65.4% in the estuary. The spatial distribution of ∑6PAEs in water and sediment phases showed that the riverside environment had influence on the distribution pattern. The reconstruction profile of the PAE congeners and the ∑6PAEs vs the depth of the sediment core indicated that PAEs became increasingly present pollutants around 2006 in the Jiulong River. The results of the potential ecological risk assessment of the RQ method revealed that DIBP and DEHP posed a high risk because of their relatively higher concentrations, while DBP and DINP posed a medium risk to the aquatic system. The baseline data of PAEs in this river will be benefits to the regulatory attention and future strategies of the pollutants control along the river network.

Sedimentary records of polycyclic aromatic hydrocarbons (PAHs) in remote lakes across the Tibetan Plateau.

Sediment cores from five lakes across the Tibetan Plateau were used as natural archives to study the time trends of polycyclic aromatic hydrocarbons (PAHs). The depositional flux of PAHs generally showed an increasing trend from the deeper layers towards the upper layer sediments. The fluxes of PAHs were low with little variability before the 1950s, and then gradually increased to the late 1980s, with a faster increasing rate after the 1990s. This temporal pattern is clearly different compared with those remote lakes across the European mountains when PAHs started to decrease during the period 1960s-1980s. The difference of the temporal trend was attributed to differences in the economic development stages and energy structure between these regions. PAHs are dominated by the lighter 2&3-ring homologues with the averaged percentage over 87%, while it is notable that the percentage of heavier 4-6 ring PAHs generally increased in recent years, which suggests the contribution of local high-temperature combustion sources becoming more predominant.

Aproximación histórica tendencial a la superación bioética del médico general integral para la práctica pediátrica

RESUMEN El desarrollo histórico supone la evolución de los procesos de superación del médico general integral e implica considerar los saberes bioéticos en beneficio de un mejor desempeño en la atención a niños y adolescentes en el contexto comunitario. El trabajo tuvo el objetivo de exponer los elementos teórico-prácticos que conforman una aproximación histórica-tendencial a la superación bioética del médico general integral para la práctica pediátrica, en el periodo de 1984 al 2020. Se utilizaron métodos teóricos: análisis-síntesis, histórico-lógico y hermenéutico. Se revisaron normativas, indicaciones y resoluciones relacionadas con la docencia médica y la superación. El estudio evidenció un desarrollo progresivo de acciones y estrategias que conciben la integración de contenidos bioético-pediátricos en la superación del médico general integral. Se identificaron aspectos didáctico-metodológicos que advierten sobre las posibilidades de continuar perfeccionando la preparación del profesional a partir de propuestas didácticas que favorezcan la apropiación de saberes integrados.

ABSTRACT The historical development supports the evolution of the improvement processes of comprehensive general doctor and implies considering bioethical knowledge in benefit of a better performance in the care of children and adolescents in the comunity context. The objective of this work dealt with the practical-theoretical elements that make up a historical trend approach to the bioethical improvement of the comprehensive general doctor for the pediatric practice at the period from 1984 to 2020. Analysis-synthesis, historical-logical and hermeneutical were the theoretical methods used. Regulations, indications and resolutions related to medical teaching and improvement were reviewed. The study showed a progressive development of actions and strategies that conceive the integration of pediatric bioethics content in the improvement of the comprehensive general doctor. Didactic-methodological aspects were identified that warn about the possibilities to continue improving the professional preparation based on didactic proposals that favor the appropriation of integrated knowledge.

Historical trend in heavy metal pollution in core sediments from the Masan Bay, Korea.

The spatiotemporal distribution and their mass accumulation rate (MAR) of heavy metals were investigated to evaluate the time-dependent historical trends of heavy metal concentration. The three short cores used for this study were collected from the catchment area (MS-PC5, 60cm length), the central part (MS-PC4, 40cm length) and the offshore (MS-PC2, 60cm length) of the Masan Bay, Korea. The concentration of heavy metals (Co, Ni, Cu, Zn, Cr and Pb) in catchment area is as much as 1.5-2 times higher than central part of the Bay, and about 2 times higher than offshore area approximately. In particular, MAR of metals (Cu, Zn and Pb) show clear spatiotemporal variation, so that MAR's of heavy metal may provide more accurate information in evaluating the degree of pollution. Temporally, the heavy metal concentration had been increased since the late 1970s, but it seems to decrease again since the 2004yr in catchment area. This may came from concentrated efforts for the government to reduce industrial waste release.