Detection of a changepoint, a mean-shift accompanied with a trend change, in short time-series with autocorrelation

Sturludóttir, Erla; Gunnlaugsdóttir, Helga; Nielsen, Ólafur K.; Stefansson, Gunnar

doi:10.1080/03610918.2014.1002849

Cited by 18 publications

(16 citation statements)

References 14 publications

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“…For PFOA in abiotic samples, the independent change point analysis revealed change points (Additional file 7, Figure S17) for sediment cores in three separate studies in Canada/USA [90], China [64] and Japan [3]. For the two cores in the Canada/USA study [90] where change points were identified (stations 1004 and 1034), statistically significant increasing trends were observed before and after the change points (in 1979 and 1988, respectively).…”

Section: Pfoa (C8 Pfca)mentioning

confidence: 95%

“…However, in no cases were there significant declining trends before or after a change point and change points were identified in the 1970s and 1980s well before any known intervention. In Chinese sediment cores [64], statistically significant increasing temporal trends were observed for PFHpA, PFNA, PFDA, PFUnDA, PFTrDA and PFTeDA.…”

Section: Other Pfcas (C7 C9-c14 Pfcas)mentioning

confidence: 98%

“…For the two cores in the Canada/USA study [90] where change points were identified (stations 1004 and 1034), statistically significant increasing trends were observed before and after the change points (in 1979 and 1988, respectively). For the Chinese study [64], there was no significant temporal trend in one sediment core (core 1) before the change point in 1967, after which a significant increasing trend was observed. For the two other cores in the Chinese study [64] (cores 2 and 3) no change point was detected.…”

Section: Pfoa (C8 Pfca)mentioning

confidence: 99%

“…For the Chinese study [64], there was no significant temporal trend in one sediment core (core 1) before the change point in 1967, after which a significant increasing trend was observed. For the two other cores in the Chinese study [64] (cores 2 and 3) no change point was detected. For the Japanese study [3], there was no statistically significant trend observed before or after the change point in 2001.…”

Section: Pfoa (C8 Pfca)mentioning

confidence: 99%

“…To detect a changepoint we used a technique similar to that outlined by Sturludottir et al [64]. The whole time-series was repeatedly divided into two parts with at least 3 years in each part and log-linear regression lines were fitted to each part and the residual variance was recorded for each combination.…”

Section: Data Synthesis and Presentationmentioning

confidence: 99%

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What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review

Land¹,

Wit²,

Bignert³

et al. 2018

Environ Evid

162

122

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Background: There is a concern that continued emissions of man-made per-and polyfluoroalkyl substances (PFASs) may cause environmental and human health effects. Now widespread in human populations and in the environment, several PFASs are also present in remote regions of the world, but the environmental transport and fate of PFASs are not well understood. Phasing out the manufacture of some types of PFASs started in 2000 and further regulatory and voluntary actions have followed. The objective of this review is to understand the effects of these actions on global scale PFAS concentrations.Methods: Searches for primary research studies reporting on temporal variations of PFAS concentrations were performed in bibliographic databases, on the internet, through stakeholder contacts and in review bibliographies. No time, document type, language or geographical constraints were applied in the searches. Relevant subjects included human and environmental samples. Two authors screened all retrieved articles. Dual screening of 10% of the articles was performed at title/abstract and full-text levels by all authors. Kappa tests were used to test consistency. Relevant articles were critically appraised by four reviewers, with double checking of 20% of the articles by a second reviewer. Meta-analysis of included temporal trends was considered but judged to not be appropriate. The trends were therefore discussed in a narrative synthesis.

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Section: Pfoa (C8 Pfca)mentioning

confidence: 95%

Section: Other Pfcas (C7 C9-c14 Pfcas)mentioning

confidence: 98%

Section: Pfoa (C8 Pfca)mentioning

confidence: 99%

Section: Pfoa (C8 Pfca)mentioning

confidence: 99%

Section: Data Synthesis and Presentationmentioning

confidence: 99%

See 3 more Smart Citations

What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review

Land¹,

Wit²,

Bignert³

et al. 2018

Environ Evid

162

122

View full text Add to dashboard Cite

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Temporal Trends (1981–2013) of Per‐ and Polyfluoroalkyl Substances and Total Fluorine in Baltic cod (Gadus morhua)

Schultes

Sandblom

Broeg

et al. 2020

Enviro Toxic and Chemistry

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Temporal trends from 1981 to 2013 of 28 per-and polyfluoroalkyl substances (PFASs) were investigated in liver tissue of cod (Gadus morhua) sampled near southeast Gotland, in the Baltic Sea. A total of 10 PFASs were detected, with ∑ 28 PFAS geometric mean concentrations ranging from 6.03 to 23.9 ng/g ww. Perfluorooctane sulfonate (PFOS) was the predominant PFAS, which increased at a rate of 3.4% per year. Most long-chain perfluoroalkyl carboxylic acids increased at rates of 3.9 to 7.3% per year except for perfluorooctanoate (PFOA), which did not change significantly over time. The perfluoroalkyl acid precursors perfluorooctane sulfonamide (FOSA) and 6:2 fluorotelomer sulfonic acid were detected, of which the former (FOSA) declined at a rate of -4.4% per year, possibly reflecting its phase-out starting in 2000. An alternate time trend analysis from 2000 to 2013 produced slightly different results, with most compounds increasing at slower rates compared to the entire study period. An exception was perfluorohexane sulfonate (PFHxS), increasing at a faster rate of 3.7% measured from 2000 on, compared to the 3.0% per year measured starting from 1981. Analysis of the total fluorine content of the samples revealed large amounts of unidentified fluorine; however, its composition (organic or inorganic) remains unclear. Significant negative correlations were found between concentrations of individual PFASs (with the exception of PFOS) and liver somatic index. In addition, body length was negatively correlated with PFOA and perfluorononanoate, but positively correlated with perfluorododecanoate (PFDoDA) and FOSA. Additional studies on endocrine, immunological, and metabolic effects of PFAS in marine fish are essential to assess the environmental risk of these substances. Environ Toxicol Chem 2020;39:300-309.

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Evaluation of ptarmigan management with a population reconstruction model

2018

Self Cite

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The rock ptarmigan (Lagopus muta) is a popular game bird in Iceland, but the population has endured a long‐term decline. A hunting ban was enforced in 2003, but 2 years later hunting was allowed again with added restrictions. The aim of this study was to investigate the effects of a change in hunting regulations on the ptarmigan population in northeast Iceland, 1998–2013, using a population reconstruction model and to estimate the abundance of juveniles and adults, natural survival, and harvest mortality. The estimated abundance at the beginning of the hunting season ranged from 42,000 (95% CI = 36,000–49,000) birds in 2002 to 158,000 (95% CI = 105,000–250,000) in 1998. The natural survival of adult rock ptarmigan was density dependent and ranged from 36% to 65% (95% CI = 30–75%). Survival for juveniles was constant and was estimated to be 19% (95% CI = 18–20%). We included a change point in the model to account for a change in the harvest mortality that could have occurred with the changes in the hunting regulations. The results indicated that the change in hunting regulations did reduce ptarmigan harvest mortality and changed the harvest strategies of hunters. Inclusion of a change point in models is useful for managers to test if a change in regulations had an effect on the target population. © 2018 The Wildlife Society.

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Detection of a changepoint, a mean-shift accompanied with a trend change, in short time-series with autocorrelation

Cited by 18 publications

References 14 publications

What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review

What is the effect of phasing out long-chain per- and polyfluoroalkyl substances on the concentrations of perfluoroalkyl acids and their precursors in the environment? A systematic review

Temporal Trends (1981–2013) of Per‐ and Polyfluoroalkyl Substances and Total Fluorine in Baltic cod (Gadus morhua)

Evaluation of ptarmigan management with a population reconstruction model

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