Examining 239+240 Pu, 210 Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia

Sanders, Christian J.; Santos, Isaac R.; Maher, Damien T.; Breithaupt, Joshua L.; Smoak, Joseph M.; Ketterer, Michael E.; Call, Mitchell; Sanders, Luciana M.; Eyre, Bradley D.

doi:10.1016/j.jenvrad.2015.04.018

Cited by 71 publications

(33 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Samples were prepared for Pu dating following the method of Ketterer et al (2004) with modifications to enable larger sample mass to be processed as a result of the likely lower Pu concentrations in the Southern Hemisphere (Sanders et al, 2016). To obtain a larger mass, sediment intervals were joined and homogenized so the sediment intervals for the 240+239 Pu dating was 4 cm intervals.…”

Section: Methodsmentioning

confidence: 99%

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

et al. 2018

Self Cite

View full text Add to dashboard Cite

Abstract. Forests along the Amazon Basin produce significant quantities of organic material, a portion of which is deposited in floodplain lakes. Deforestation in the watershed may then have potentially important effects on the carbon fluxes. In this study, a sediment core was extracted from an Amazon floodplain lake to examine the relationship between carbon burial and changing land cover and land use. Historical records from the 1930s and satellite data from the 1970s were used to calculate deforestation rates between 1930 to 1970 and 1970 to 2010 in four zones with different distances from the margins of the lake and its tributaries (100, 500, 1000 and 6000 m buffers). A sediment accumulation rate of ∼ 4 mm yr −1 for the previous ∼ 120 years was determined from the 240+239 Pu signatures and the excess 210 Pb method. The carbon burial rates ranged between 85 and 298 g C m −2 yr −1 , with pulses of high carbon burial in the 1950s, originating from the forest vegetation as indicated by δ 13 C and δ 15 N signatures. Our results revealed a potentially important spatial dependence of the organic carbon (OC) burial in Amazon lacustrine sediments in relation to deforestation rates in the catchment. These deforestation rates were more intense in the riparian vegetation (100 m buffer) during the period 1930 to 1970 and the larger open water areas (500, 1000 and 6000 m buffer) during 1970 to 2010. The continued removal of vegetation from the interior of the forest was not related to the peak of OC burial in the lake, but only the riparian deforestation which peaked during the 1950s. Therefore, this supports the conservation priority of riparian forests as an important management practice for Amazon flooded areas. Our findings suggest the importance of abrupt and temporary events in which some of the biomass released by deforestation, especially restricted to areas along open water edges, might reach the depositional environments in the floodplain of the Amazon Basin.

show abstract

Section: Methodsmentioning

confidence: 99%

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…These isotopes can also be used as tracers of bioturbation (Crusius et al, 2004) or acceleration of sedimentation during the past 50 years (Appleby, 1998;Cearreta et al, 2002;Lynch et al, 1989;Sharma et al, 1987 in these regions (Kelley et al, 1999;Ruiz-Fernández and Hillaire-Marcel, 2009), the greater solubility of 137 Cs in seawater and the presence of sands, particularly in seagrass sediments (Koch, 2001), are conditions that do not favor the adsorption of 137 Cs (He and Walling, 1996a), and may lead to its mobility (Davis et al, 1984), due to its low partition coefficient in Pu half-life = 6,500 yr), although are also dependent on the distribution of bomb-test fallout, would appear to offer several advantages over 137 Cs in these environments, as 239+240 Pu is relatively immobile under 5 both freshwater and saltwater conditions (Crusius and Anderson, 1995). For instance, Sanders et al (2016) determined sedimentation rates and 239+240 Pu penetration depths to study nutrient and C org accumulation in intertidal mangrove mudflats of Moreton Bay, Australia. Nevertheless and because of the limitations to validate older 210 Pb dates near the base of the core, and the low inventories of bomb-test fallout in coarse sediments, alternative tracers might need to be used.…”

mentioning

confidence: 99%

Reviews and syntheses: <sup>210</sup>Pb-derived sediment and carbon accumulation rates in vegetated coastal ecosystems: setting the record straight

Arias‐Ortiz¹,

Masqué²,

García-Orellana³

et al. 2018

Preprint

View full text Add to dashboard Cite

Abstract. Vegetated coastal ecosystems, including tidal marsh, mangrove and seagrass, are being increasingly assessed for their potential in carbon dioxide sequestration worldwide. However, there is a paucity of studies that have effectively estimated the accumulation rates of sediment organic carbon (C org ) beyond the mere quantification of C org stocks. Here, we discuss the use of the 210 Pb dating technique as a practical tool to measure the rate of C org accumulation in vegetated coastal ecosystems. We critically review the status of

show abstract

“…The 210 Pb and 226 Ra activities were calculated by using a factor that includes the gamma detector efficiency, as previously determined from certified reference material IAEA-300 (Baltic Sea Sediment) and the gamma-ray intensity. The 210 Pb and 226 Ra activities were measured using the 46.5 KeV and 351.9 KeV gamma peaks, respectively (Sanders et al, 2016). Prior to radionuclide measurements, samples were set aside for at least 3 weeks, to allow for 222 Rn ingrowth and to establish secular equilibrium between 226 Ra and its granddaughter 214 Pb.…”

Section: Methodsmentioning

confidence: 99%

“…Anthropogenic radionuclides from the Cold War era above-ground nuclear tests are routinely used to date sediments around the globe (Ketterer et al, 2004a;Sanders et al, 2016;Sanders et al, 2010). These radionuclides, including Pu isotopes, fission products ( 137 Cs,90 Sr, 129 I) and activation products ( 3 H, 14 C), were deposited globally from the early 1950's to the late 1960's from USA and former Soviet Union nuclear bomb testing (Abril, 2003;Alhajji et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

et al. 2017

View full text Add to dashboard Cite

Anthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20 th century. The 240 Pu + 239 Pu ( 240+239 Pu) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year -1 ), Tapajos (10.2 and 2.4 mm year -1 ) and Madeira (3.4, 4.2 and 6.2 mm year -1 ). The results from this study show that 240+239 Pu fallout activities, and the well documented ( 240 Pu/ 239 Pu) atomic ratios of the above ground nuclear tests which began in the 1950's, are sufficient and well preserved in Amazon floodplain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the 240+239 Pu and 210 Pb dating methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20 th century. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous ~60 years) along the Amazon Basin.

show abstract

Examining 239+240 Pu, 210 Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia

Cited by 71 publications

References 43 publications

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

Reviews and syntheses: <sup>210</sup>Pb-derived sediment and carbon accumulation rates in vegetated coastal ecosystems: setting the record straight

<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

Contact Info

Product

Resources

About

Examining 239+240 Pu, 210 Pb and historical events to determine carbon, nitrogen and phosphorus burial in mangrove sediments of Moreton Bay, Australia

Cited by 71 publications

References 43 publications

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

Historic carbon burial spike in an Amazon floodplain lake linked to riparian deforestation near Santarém, Brazil

Reviews and syntheses: &lt;sup&gt;210&lt;/sup&gt;Pb-derived sediment and carbon accumulation rates in vegetated coastal ecosystems: setting the record straight

<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

Contact Info

Product

Resources

About

Reviews and syntheses: <sup>210</sup>Pb-derived sediment and carbon accumulation rates in vegetated coastal ecosystems: setting the record straight