Sediment, carbon and nitrogen capture in mountainous irrigated rice systems

Anthropogenic influences have caused landscapes to change worldwide in the last decades, and changes have been particularly intense in montane Southeast Asia. Traditional swiddening cropping systems with low environmental impacts have been largely replaced by forms of permanent upland cultivation, often with maize. The associated soil fertility loss at the plot scale is well documented. In valley bottoms of these areas, paddies have been cultivated for centuries, and are considered some of the most sustainable production systems in the world in part maintained by the influx of fertile sediments through irrigation. Altered cropping patterns on the slopes therefore also have potential repercussions on rice production, and hence on food security, but the consequences of shifted sediment and nutrient redistribution at the landscape scale are not well understood. In order to assess these effects, methodologies were developed in this thesis that enable low-cost, continuous monitoring of sediment and nutrient transport in irrigated watersheds (Chapter 2), as well as quantification of the uncertainty on constituent loads (Chapter 3). These methods are applied in a case study to determine sediment, organic carbon and nitrogen trap efficiency of paddy rice fields in a mountainous catchment in Vietnam (Chapters 4 and 5). The upland area had an average erosion rate of 7.5 Mg ha-1 a-1. Sediment inputs to the paddy area consisted of 64 Mg ha-1 a-1, of which irrigation water provided 75% and the remainder came from erosion during rainfall events. Erosion contributed one third of the sand inputs, while sediments from irrigation water were predominantly silty, demonstrating the protective effect of the reservoir which buffered the coarse, unfertile material. Almost half of the total sediment inputs were trapped in the rice area. As all of the sand inputs remained in the rice fields, the upland-lowland linkages could entail a long-term change in topsoil fertility and eventually a rice yield loss. Quantification of nutrient re-allocation in Chapter 5 showed that irrigation was even more important as a driver of sediment-associated organic carbon and nitrogen inputs into the rice fields, contributing 90% of carbon and virtually all nitrogen. Direct contributions from erosion to the nutrient status of the paddies were negligible, again underscoring the protective function of the surface reservoir in buffering irrigated areas from unfertile sediment inputs. 88% of the sediment-associated organic carbon and 93% of the nitrogen were captured by the rice fields. Irrigation water additionally brought in dissolved nitrogen, resulting in a total nitrogen input of 1.11 Mg ha 1 a-1. Of this amount, 24% was determined to be in the plant-available forms of ammonium and nitrate, a contribution equivalent to 66% of the recommended nitrogen application via chemical fertilizer. The dependence of paddy soil fertility on agricultural practices in the uplands illustrates the vulnerability of irrigated rice to unsustainable land use in the surrounding landscape. Unfortunately, alternatives for upland land use that are not detrimental to soil quality are hard to come by, due to the economic reality of high maize prices on the world market. Conservation measures and agroforestry systems offer potential, but without some form of payment for environmental services, adoption rates remain low. Finding sustainable solutions is especially urgent as climate change is likely to increase the number of extreme rainfall events and hence intensify the redistribution processes already taking place. In this light, the role of trapping elements in landscapes such as paddy fields and surface reservoirs becomes more important as well. As these features are widely spread throughout tropical landscapes, their role in global sediment and nutrient cycles must be taken into account. The methodologies developed in this thesis, for sediment and nutrient transport monitoring and for uncertainty assessment, can aid in closing the data gap that currently hinders a reliable assessment of the consequences of anthropogenic and climate change, both on food security and on environmental impacts, locally, regionally and globally.Weltweit haben anthropogene Einflüsse Landschaften in den letzten Jahrzehnten wesentlich verändert. Dieser Wandel war besonders stark in Bergregionen Südostasiens. Traditioneller Wanderackerbau mit geringen Umweltauswirkungen wurde weitgehend durch Formen permanenten Anbaus - oft auf Basis von Mais - ersetzt. Der damit einhergehende Verlust an Bodenfruchtbarkeit auf Feldebene ist gut beschrieben. In Tallagen dieser Region werden Reisfelder seit Jahrhunderten kultiviert und gelten als einige der nachhaltigsten Pflanzenproduktionssysteme der Welt. Dies wird teilweise durch den Eintrag fruchtbarer Sedimente über das Bewässerungswasser ermöglicht. Veränderte Landnutzungsmuster in Hanglagen können sich daher auch auf die Reisproduktion auswirken und in Folge die Nahrungssicherung beeinträchtigen. Allerdings werden die Konsequenzen einer veränderten Sediment- und Nährstoffumverteilung auf der Landschaftsebene bisher kaum verstanden. Um diese Auswirkungen zu erfassen, wurden im Rahmen dieser Dissertation Methoden entwickelt, die ein kostengünstiges, kontinuierliches Monitoring der Sediment- und Nährstofftransports in bewässerten Wassereinzugsgebieten (Kapitel 2) sowie die Quantifizierung von Ungewissheiten in deren Zusammensetzung erlauben (Kapitel 3). Diese Methoden werden in einer Fallstudie angewandt, um den Wirkungsgrad des Sedimenteintrags in bewässerten Reisfeldern auf Wassereinzugsgebietsebene in einer Bergregion Vietnams zu bestimmen (Kapitel 4 und 5). In der Hangzone lag die durchschnittliche Erosionsrate bei 7.5 Mg/ha und Jahr. Der Sedimenteintrag in die Nassreisfläche betrug 64 Mg/ha und Jahr. Hierzu trug das Bewässerungswasser 75 % bei, der Rest durch Erosion während Starkregenereignissen. Erosion lieferte ein Drittel des Sandeintrags, während die Sedimente des Bewässerungswassers überwiegend schluffig waren. Dies demonstriert den Puffereffekt des Stausees, der das gröbere, unfruchtbare Material aufnahm. Fast die Hälfte der Sedimentfracht verblieb in der Reisanbauzone. Da der gesamte Sandanteil in den Reisfeldern verblieb, könnte sich in der Beziehung zwischen Hang- und Tallagen langfristig eine Veränderung der Bodenfruchtbarkeit im Oberboden einstellen und in Folge eventuell ein Verlust an Reiserträgen. Die Quantifizierung der Nährstoffumverteilung in Kapitel 5 zeigte, dass die Bewässerung einen noch größeren Einfluss auf die Einträge an organischem Kohlenstoff und Stickstoff in die Reisfelder hatte und dabei 90% des Kohlenstoffs und fast den gesamten Stickstoff beitrug. Direkte Beiträge der Erosion zur Nährstoffversorgung der Reisfelder waren vernachlässigbar, was wiederum die Schutzfunktion des Stausees im Hinblick auf den Schutz des Bewässerungsgebietes vor unfruchtbaren Sedimenteinträgen unterstreicht. 88% der Sedimentfracht an organischem Kohlenstoff und 93% des Stickstoffs verblieben in den Reisfeldern. Das Bewässerungswasser trug zusätzlich gelösten Stickstoff ein, was einen Gesamteintrag an Stickstoff in Höhe von 1.11 Mg ha-1 a-1 zur Folge hatte. Hiervon waren 24% pflanzenverfügbar in Form von Ammonium und Nitrat, wodurch das Bewässerungswasser einen Beitrag zum pflanzenverfügbaren N lieferte, äquivalent zu der Hälfte der empfohlenen chemischen Dünger-Anwendung. Die Abhängigkeit der Bodenfruchtbarkeit der Reisböden von Anbaupraktiken in den Hanglagen illustriert die Anfälligkeit des Nassreises gegenüber einer nicht nachhaltigen Landnutzung in der umgebenden Landschaft. Alternativen für eine Nutzung der Hanglagen, die nicht abträglich für die Bodenqualität sind, sind leider rar wegen der hohen Weltmarktpreise für Mais. Bodenschonende Anbausysteme oder Agroforstsysteme haben Potenzial, werden aber ohne irgendeine Form der Kompensationszahlung für Ökosystemleistungen in ihrer Übernahmerate gering bleiben. Das Finden nachhaltiger Lösungen ist besonders dringend, da der Klimawandel vermutlich eine Zunahme extremer Regenereignisse bewirkt, in deren Folge die bereits bestehenden Umlagerungsprozesse noch intensiviert werden. In diesem Zusammenhang gewinnen Landschaftselemente wie Nassreisfelder und Stauseen als Filter zunehmend an Bedeutung. Da diese Merkmale in Landschaften der Tropen weit verbreitet sind, muss man ihre Rolle im Zusammenhang mit globalen Sediment- und Nährstoffkreisläufen sehen. Die im Rahmen dieser Dissertation zum Monitoring von Sediment- und Nährstofftransport sowie zur Überprüfung von Messunsicherheit entwickelten Methoden können helfen, Wissenslücken zu schließen, die aktuell eine verlässliche Einschätzung der Konsequenzen anthropogenem Handelns einschließlich der Auswirkungen des Klimawandels in Hinblick auf Nahrungssicherheit und Auswirkungen auf die Umwelt im lokalen, regionalen und globalen Kontext erschweren

Expressions of self-ageism in four European countries:a comparative analysis of predictors across cultural contexts

Self-ageism has a significant negative impact on older people's ageing experiences and health outcomes. Despite ample evidence on cross-cultural ageism, studies have rarely looked into the way cultural contexts affect self-ageism. In this article, we compare expressions of self-ageism and its possible predictors across four European countries based on two questionnaires in a study sample of 2,494 individuals aged 55 and older. We explore how predictors of self-ageism are moderated by cultural values in a comparative fixed-effects regression model. We empirically show that similarly to ageism, self-ageism is not present in the same way and to the same extent in every country. Moreover, the level to which cultures value hierarchy and intellectual autonomy significantly moderates the association between self-ageism and individual predictors of self-ageism. Our study adds to the small existing body of work on self-ageism by confirming empirically that certain expressions of self-ageism and individual predictors are susceptible to change in different cultural contexts. Our research results suggest that self-ageism interventions may benefit from a culturally sensitive approach and imply that more culturally diverse comparisons of self-ageism are necessary to figure out fitting ways to reduce self-ageism

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Fossil redox-conditions influence organic matter composition in loess paleosols

The soil memory recorded in paleosols of loess-paleosol sequences is an important contributor to our understanding of past climatic conditions. Molecular proxies based on the organic matter preserved in paleosols form an essential part of this record, but the long-term preservation of SOM is poorly understood, especially for sediment traps and slope profiles. This paper addresses the composition of organic material from the Early Weichselian A-horizons of the Rocourt paleosol, a major paleostratigraphic marker for the Eemian and Early Weichselian in Western Europe. NaOH-extractable organic matter from an exceptionally thick Rocourt profile in the Kesselt Quarry (Belgian Loess Belt) was analyzed by pyrolysis-Gas Chromatography/Mass Spectrometry (pyrolysis-GC/MS) and the results evaluated against paleopedological data. The molecular composition of the organic matter at Kesselt was compared with reference samples from two nearby quarries (including the type locality at Veldwezelt-Hezerwater), and to a sample from the contemporary Nussloch sequence in Germany. The SOM composition found at the four sites indicated a large content of microbial matter and was dominated by carbohydrates and N compounds, many of which were not reported before from SOM pyrolysates. Differences in the molecular composition between samples, both within profiles and between sites, coincided with differences in landscape position (slope-shoulder-plateau) and fossil redox conditions (surface gleys). Samples form drier and more upland situations contained more burnt material, while samples from slope profiles and surface gleys contained even more microbial material, in particular chitin. Results therefore suggest that the admixture of microbial SOM is considerable in loess-paleosols and that differences in edaphic conditions (in particular slope position and soil moisture) and occurrence of wildfires are important for the long-term preservation of SOM. These should therefore be considered when interpreting biogeochemical proxies.status: publishe

Fossil redox-conditions influence organic matter composition in loess paleosols

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Paleo-pedological record of the Rocourt Pedosequence at Veldwezelt–Hezerwater (Belgian Pleistocene loess belt). Part 1 : Evolution of the parent material

As the environment influences soil formation, loess–paleosols are important archives of former climatic conditions. However, this record is highly complex and all features need to be evaluated in order to obtain consistent information on soil formation. This study revises the pedological record of the Rocourt-paleosol complex, an important pedo-stratigraphic marker for the Eemian and Early Weichselian, at an exceptionally well-preserved in-situ sequence (Veldwezelt–Hezerwater, Belgian loess belt). Contrasting hypotheses exist considering the evolution of the parent material after the deposition of the Saalian loess and on the importance of aggrading aeolian deposition. In this study, soil morphological features and depth functions of X-ray diffraction, grain-size distribution, CEC, base saturation, total Fe, Al, K, Na and Ca content, pH and electrical conductivity were established to reconstruct deposition dynamics, weathering and carbonate content of the parent material. Texture analysis confirms the petrostratigraphic homogeneity of the parent material and suggests that it developed under a regime of fluctuating rates of primary dust deposition intermixed with periods of (fluvial) reworking of the dust. Strong weathering was identified in the lower stratigraphic unit, supporting the general consensus that it formed during the Eemian in Saalian loess. Less information is present to confirm the origin of the upper, less developed illuvial units, which may have formed by welding or by pedogenesis in locally edistributed or aeolian material. The overlying A-horizons are clearly less weathered,and evidence for early recalcification indicates that deposition of unweathered, calcareous sediments gained importance during the formation of these horizons.status: publishe

Patterns of soil organic Carbon, Nitrogen and 137Cs in the high wetlands at the foot of the Huayna-Potosí Glacier (La Paz, Bolivia)

1 .pdf copy (1 Pag.) of the abstract published by the Organization. © Author(s) 2018. CC Attribution 4.0 license.Rapid changes of glacierized areas of the Andes in Bolivia are affecting high altitude wetlands threatening their sustainability with further socioeconomic consequences for the population in the area. At the food of Huayna- Potosí (16 S, 68 W, 6088 m a.s.l.) in the Cordillera Real there are eight permanent wetlands (bofedales) that are affected by the rapid retreat of the Huayna-Potosí Glacier. Their characteristic perennial vegetation fulfills the function of forage provision to the camelid cattle typical of the region. Groundwater, rain, melting glaciers and snow are sources of water for these bofedales that play an important role in the storage and provision of water to the Tuni reservoir that supplies water to La Paz. During a two weeks expedition in the frame of IAEA INT5153 project in May 2017, a field survey of the Huayna-Potosí Glacier area was undertaken following the glacier retreat where rocks highly reactive are recently exposed.Peer reviewe

Combining 137Cs and soil organic carbon for assessing patterns of soil formation in the rapidly changing proglacial environment of the Grey Glacier (Torres del Paine, Chilean Patagonia)

1 .pdf copy (1 Pag.) of the abstract published by the Organization. © Author(s) 2019. CC Attribution 4.0 license.As in other regions of the world, glaciers in South America like in Torres del Paine National Park are shrinking. The trends of increasing temperatures would accelerate melting process that will affect not only populations but also natural resources as water and soil that support life. Recent works in other polar and cold regions have shown the usefulness of combining fallout radionuclides and soil organic carbon (SOC) for tracking recent glacier retreat on glacial formations of proglacial environments.Peer reviewe

Data from: Reference data for the Ruff Figural Fluency Test stratified by age and educational level

The Ruff Figural Fluency Test (RFFT) was developed to avoid the difficulties that were encountered in earlier tests of figural fluency. Although the test characteristics of the RFFT seem to be good and it is a valuable addition to neuropsychological assessments, reference data are still scarce. To this aim, we required 2,404 community dwelling persons in Groningen, the Netherlands to perform the RFFT. All 1,651 persons with a complete RFFT and known educational level formed the reference sample. Their age ranged from 35 to 82 years and their educational level from primary school to university grade. Ninety-six percent of the persons were of Western European descent. All tests were analyzed by two independent examiners and subsequently three measures were calculated: number of unique designs, number of perseverative errors and error ratio. The main finding was that performance on the RFFT was dependent on age and educational level. This was not only observed in older persons but also in young and middle-aged persons. Reference data for the three RFFT measures are presented in groups of five years of age ranging from 35-39 years to 75 years or older

Data from: Longitudinal Study of Performance on the Ruff Figural Fluency Test in Persons Aged 35 Years or Older

The Ruff Figural Fluency Test (RFFT) is a cognitive test tomeasure executive function. Longitudinal studies have shown thatrepeated testing improves performance on the RFFT. Such a practice effect may hinder the interpretation of test results in a clinical setting. Therefore, we investigated the longitudinal performance on the RFFT in persons aged 35-82 years. Performance on the RFFT was measured three times over an average follow-up period of six years in 2,515 participants of the Prevention of REnal and Vascular ENd-stage Disease (PREVEND) study in Groningen, the Netherlands: 53% men; mean age (SD), 53 (10) years. The effect of consecutive measurements on performance on the RFFT was investigated with linear multilevel regression models that also included age, gender, educational level and the interaction term consecutive measurement number x age as independent variables. It was found that the mean (SD) number of unique designs on the RFFT increased from 73 (26) at the first measurement to 79 (27) at the second measurement and to 83 (26) at the third measurement