Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    How natural processes contribute to flood protection - A sustainable adaptation scheme for a wide green dike
    Marijnissen, Richard ; Esselink, Peter ; Kok, Matthijs ; Kroeze, Carolien ; Loon-Steensma, Jantsje M. van - \ 2020
    Science of the Total Environment 739 (2020). - ISSN 0048-9697
    Clay mining - Climate adaptation - Flood risk - Nature-based solutions - Salt marsh - Sea-level rise

    Effective adaptation to sea-level rise is critical for future flood protection. Nature-based solutions including salt marshes have been proposed to naturally enhance coastal infrastructure. A gently sloping grass-covered dike (i.e. Wide Green Dike) can be strengthened with clay accumulating locally in the salt marsh. This study explores the feasibility of extracting salt-marsh sediment for dike reinforcement as a climate adaptation strategy in several sea-level rise scenarios, using the Wide Green Dike in the Dutch part of the Ems-Dollard estuary as a case study. A 0-D sedimentation model was combined with a wave propagation model, and probabilistic models for wave impact and wave overtopping. This model system was used to determine the area of borrow pits required to supply clay for adequate dikes under different sea-level rise scenarios. For medium to high sea-level rise scenarios (>102 cm by 2100) thickening of the clay layer on the dike is required to compensate for the larger waves resulting from insufficient marsh accretion. The model results indicate that for our case study roughly 9.4 ha of borrow pit is sufficient to supply clay for 1 km of dike reinforcement until 2100. The simulated borrow pits are refilled within 22 simulation years on average, and infilling is projected to accelerate with sea-level rise and pit depth. This study highlights the potential of salt marshes as an asset for adapting flood defences in the future.

    Comments on the article of "Agriculture green development : A model for China and the world"
    Kroeze, Carolien - \ 2020
    Frontiers of Agricultural Science and Engineering 7 (2020)1. - ISSN 2095-7505 - p. 106 - 107.
    Assessing seasonal nitrogen export to large tropical lakes
    Goshu, Goraw ; Strokal, M. ; Kroeze, C. ; Koelmans, A.A. ; Klein, J.J.M. de - \ 2020
    Science of the Total Environment 731 (2020). - ISSN 0048-9697
    Eutrophication - Modelling seasonality - Nitrogen - River export - Sub-basin - Tropical Lake

    Rivers are exporting increasing amounts of nitrogen (N) to lakes, which is leading to eutrophication. However, the seasonality apparent in nutrient loading, especially in tropical areas, is thus far only partially understood. This study aims to better understand the seasonality and the sources of dissolved inorganic nitrogen (DIN) inputs from sub-basins to tropical lakes. We integrated existing approaches into a seasonal model that accounts for seasonality in human activities, meteorology and hydrology, and we applied the model to the sub-basins of a representative tropical lake: Lake Tana, Ethiopia. The model quantifies the river export of DIN by season, source and sub-basin and also accounts for open defecation to land as a diffuse source of N in rivers. Seasonality parameters were calibrated, and model outputs were validated against measured nitrogen loads in the main river outlets. The calibrated model showed good agreement with the measured nitrogen loads at the outflow of the main rivers. The model distinguishes four seasons: rainy (July–September), post-rainy (October–December), dry (January–March) and pre-rainy (April–June). The river export of DIN to Lake Tana was about 9 kton in 2017 and showed spatial and temporal variability: It was highest in the rainy and lowest in the dry seasons. Diffuse sources from agriculture were important contributors of DIN to rivers in 2017, and animal manure was the dominant source in all seasons. Our seasonal sub-basins and rivers model provides opportunities to identify the main nutrient sources to the lake and to formulate effective water quality management options. An example is nutrient application level that correspond to the crop needs in the sub-basins. Furthermore, our model can be used to analyse future trends and serves as an example for other large tropical lakes experiencing eutrophication.

    Global Change Can Make Coastal Eutrophication Control in China More Difficult
    Wang, Mengru ; Kroeze, Carolien ; Strokal, Maryna ; Vliet, Michelle T.H. van; Ma, Lin - \ 2020
    Earth's Future 8 (2020)4. - ISSN 2328-4277
    Climate change - Coastal eutrophication - Nutrient export - Socio-economic change - Source attribution - Sub-basins

    Fast socio-economic development in agriculture and urbanization resulted in increasing nutrient export by rivers, causing coastal eutrophication in China. In addition, climate change may affect hydrology, and as a result, nutrient flows from land to sea. This study aims at a better understanding of how future socio-economic and climatic changes may affect coastal eutrophication in China. We modeled river export of total dissolved nitrogen (TDN) and phosphorus (TDP) in 2050 for six scenarios combining socio-economic pathways (SSPs) and Representative Concentration Pathways (RCPs). We used the newly developed MARINA 2.0 (Model to Assess River Inputs of Nutrients to seAs) model. We found that global change can make coastal eutrophication control in China more difficult. In 2050 coastal waters may be considerably more polluted or considerably cleaner than today depending on the SSP-RCP scenarios. By 2050, river export of TDN and TDP is 52% and 56% higher than in 2012, respectively, in SSP3-RCP8.5 (assuming large challenges for sustainable socio-economic development, and severe climate change). In contrast, river export of nutrients could be 56% (TDN) and 85% (TDP) lower in 2050 than in 2012 in SSP1-RCP2.6 (assuming sustainable socio-economic development, and low climate change). Climate change alone may increase river export of nutrients considerably through hydrology: We calculate 24% higher river export of TDN and 16% higher TDP for the SSP2 scenario assuming severe climate change compared to the same scenario with low climate change (SSP2-RCP8.5 vs. SSP2-RCP2.6). Policies and relevant technologies combining improved nutrient management and climate mitigation may help to improve water quality in rivers and coastal waters of China.

    Reply to Comment on "Multi-Scale Modeling of Nutrient Pollution in the Rivers of China"
    Chen, Xi ; Strokal, Maryna ; Vliet, Michelle T.H. Van; Stuiver, John ; Wang, Mengru ; Bai, Zhaohai ; Ma, Lin ; Kroeze, Carolien - \ 2020
    Environmental Science and Technology 54 (2020)3. - ISSN 0013-936X - p. 2046 - 2047.
    Reducing nutrient pollution in water systems in China: challenges, trends and solutions
    Wang, Mengru - \ 2020
    Wageningen University. Promotor(en): C. Kroeze; L. Ma. - Wageningen : Wageningen University - ISBN 9789463951975 - 254

    China has been developing fast over the last decades. Intensive human activities in food production and urbanization have led to increasing nitrogen (N) and phosphorus (P) losses to water systems, causing freshwater and coastal water pollution. Reducing water pollution is important in China, especially given its commitments to the Sustainable Development Goals (SDGs) (e.g., SDGs 6 – “clean water and sanitation” and 14 – “life below water”). Nutrient models have been used to analyze the causes of nutrient pollution in water systems and to explore solutions for China. Existing modeling studies focus on either nutrient flows in human activities (e.g., food production) at administrative (e.g., province, country) scales, or on nutrient fluxes from land to water systems at bio-geophysical scales (e.g., river basins). However, a better understanding of how human activities at the administrative scales affect nutrient fluxes at bio-geophysical scales of water systems is needed for China.

    Nutrient pollution in water systems may continue to increase in the future because of the expected changes in socio-economic development (e.g., population, economy) in China. Climate change may also influence hydrology (e.g., runoff, river discharges), and thus will influence nutrient transport in water systems (e.g., rivers). However, how socio-economic and climatic changes, together, will affect future nutrient pollution in water systems in China is not well studied. Such analysis can be done by implementing the global Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs) in nutrient models for China. Moreover, many policies in China attempt to reduce future water pollution by nutrients. However, limited insights are available on the effectiveness of these policies for reducing future water pollution by nutrients.

    The objective of this PhD thesis is to improve our understanding of nutrient pollution in water systems in China, with a focus on the challenges, trends, and solutions. To this end, I formulated six sub-objectives for my research on nutrient pollution in water systems (sub-objectives 2, 4, and 6) from human activities on land (sub-objectives 1, 3, and 5).

    Sub-objectives focusing on the challenges:

    1. To identify hotspots for nutrient losses from food production (Chapter 2)

    2. To compare nutrient loads to Lake Taihu with the critical nutrient loads of the lake (Chapter 3, case study)

    Sub-objectives focusing on the trends:

    1. To analyze how socio-economic development affects future nutrient losses from food production (Chapter 4)

    2. To analyze how global change affects future river export of nutrients to seas (Chapter 5)

    Sub-objectives focusing on the solutions:

    1. To explore how current and improved nutrient management affects future nutrient losses from food production (Chapter 6)

    2. To explore future scenarios to reduce nutrient pollution in water systems and to meet the SDGs (Chapter 7)

    To meet the objectives, I developed and applied new versions of the NUFER (NUtrient flows in Food chains, Environment and Resources use) and MARINA (Model to Assess River Inputs of Nutrients to seAs) models. I analyzed nutrient flows in China’s food system for counties, provinces and China using the NUFER model. I analyzed river export of nutrients by 12 large Chinese rivers.

    The main findings are:

    1. In recent past, nutrient losses from food production increased dramatically in China (Chapter 2)

    2. Hotspots covered less than 10% of the Chinese land, but contributed by more than half to N and P losses to the environment in 2012 (Chapter 2)

    3. To meet critical loads, river export of TDN and TDP to Lake Taihu needs to be reduced by 46–92% (Chapter 3)

    4. Opportunities are reducing synthetic fertilizer and improving wastewater treatment (Chapter 3)

    5. Nitrogen losses from food production to water systems in the future may increase by up to 65% relative to today if nutrient management does not improve (Chapter 4)

    6. Climate change makes water pollution control in China more difficult (Chapter 5)

    7. Current policies aimed at zero growth in fertilizer use are not very effective in reducing nutrient pollution from food production in China (Chapter 6)

    8. SDG 6&14 can be met with improved nutrient management in agriculture and sewage systems, efficient food consumption, and climate mitigation (Chapter 7)

    9. Future scenarios contributing to SDGs 6 and 14 may also contribute to other SDGs (Chapter 7)

    I reflected on the research in this thesis, drew five main lessons for future nutrient modeling, and discussed the implications of this thesis on future policies (Chapter 8). The main lessons are: 1) linking NUFER and MARINA models can help to better explore solutions to reduce nutrient pollution in water systems at administrative and bio-geophysical scales, 2) preferred spatial scales of modeling depending on the research objectives, 3) indicators can help to better understand and communicate the modeling results, 4) combining different types of scenarios is useful in exploring solutions in environmental modeling, and 5) the modeling approach in this thesis can be used to analyze nutrient pollution in water systems in other world regions.

    The development of recent environmental policies in China confirms two main findings of this thesis: 1) nutrient pollution in water systems has increased dramatically in China, and 2) direct discharge of animal manure and human waste are the important sources of nutrient pollution in water systems in China. My PhD thesis supports the formulation of future environmental policies for water pollution control in China. The linked NUFER-MARINA approach provides novel insights to nutrient pollution at both administrative (e.g., county, province, and country) and bio-geophysical (e.g., sub-basin) scales. Such insights are useful for formulating policies that are often implemented at administrative scales to reduce water pollution at bio-geophysical scales. The potential options for reducing water pollution proposed in this thesis can be considered by policymakers as a starting point. Further improvement of these options using the participatory approach can be done to account for different perspectives and uncertainties for policy implementation. Quantitative indicators for water pollution in this thesis are helpful in understanding and communicating the modeling results with policymakers and stakeholders. All this hopefully will contribute to reducing water pollution by nutrients, and meeting the SDGs 6 and 14 in China.

    The Sensitivity of a Dike-Marsh System to Sea-Level Rise—A Model-Based Exploration
    Marijnissen, R.J.C. ; Kok, Matthijs ; Kroeze, C. van; Loon-Steensma, J.M. van - \ 2020
    Journal of Marine Science and Engineering 8 (2020)1. - ISSN 2077-1312 - 17 p.
    Integrating natural components in flood defence infrastructure can add resilience to sea-level rise. Natural foreshores can keep pace with sea-level rise by accumulating sediment and attenuate waves before reaching the adjacent flood defences. In this study we address how natural foreshores affect the future need for dike heightening. A simplified model of vertical marsh accretion was combined with a wave model and a probabilistic evaluation of dike failure by overtopping. The sensitivity of a marsh-dike system was evaluated in relation to a combination of processes: (1) sea-level rise, (2) changes in sediment concentration, (3) a retreat of the marsh edge, and (4) compaction of the marsh. Results indicate that foreshore processes considerably affect the need for dike heightening in the future. At a low sea-level rise rate, the marshes can accrete such that dike heightening is partially mitigated. But with sea-level rise accelerating, a threshold is reached where dike heightening needs to compensate for the loss of marshes, and for increasing water levels. The level of the threshold depends mostly on the delivery of sediment and degree of compaction on the marsh; with sufficient width of the marsh, lateral erosion only has a minor effect. The study shows how processes and practices that hamper or enhance marsh development today exacerbate or alleviate the challenge of flood protection posed by accelerated sea-level rise.
    Cost-effective management of coastal eutrophication: A case study for the yangtze river basin
    Strokal, M. ; Kahil, T. ; Wada, Y. ; Albiac, J. ; Bai, Z. ; Ermolieva, T. ; Langan, S. ; Ma, L. ; Oenema, O. ; Wagner, F. ; Zhu, X. ; Kroeze, C. - \ 2020
    Resources, Conservation and Recycling 154 (2020). - ISSN 0921-3449
    Cost-effective management - Eutrophication - Integrated modelling - Nitrogen and phosphorus - Nutrient management - Waste recycling

    Many water resources are threatened with nutrient pollution worldwide. This holds for rivers exporting increasing amounts of nutrients from the intensification of food production systems and further urbanization. This riverine nutrient transport causes coastal eutrophication. This study aims to identify cost-effective management options to simultaneously reach environmental targets for river export of nitrogen and phosphorus by the Yangtze River (China) in 2050. A newly developed modelling approach is used that integrates the Model to Assess River Inputs of Nutrients to seAs (MARINA) with a cost-optimization procedure, and accounts for socio-economic developments, land use and climate changes in a spatially explicit way. The environmental targets for river export of nutrients aim to reduce the gap between baseline and desirable nutrient export. Our baseline is based on MARINA projections for future river export of nutrients, while the desirable nutrient export reflects a low eutrophication potential. Results show the possibilities to close the gap in river export of both nutrients by 80–90% at a cost of 1–3 billion $ per year in 2050. Recycling of animal waste on cropland is an important cost-effective option; reducing synthetic fertilizer inputs provides an opportunity to compensate for the additional costs of the recycling and treatment of manure and wastewater. Our study provides new insights on the combination of cost-effective management options for sub-basins of the Yangtze. This can support the design of cost-effective and sub-basin specific management options for reducing future water pollution.

    Integrative Proteomic Profiling Reveals PRC2-Dependent Epigenetic Crosstalk Maintains Ground-State Pluripotency
    Mierlo, Guido van; Dirks, René A.M. ; Clerck, Laura De; Brinkman, Arie B. ; Huth, Michelle ; Kloet, Susan L. ; Saksouk, Nehmé ; Kroeze, Leonie I. ; Willems, Sander ; Farlik, Matthias ; Bock, Christoph ; Jansen, Joop H. ; Deforce, Dieter ; Vermeulen, Michiel ; Déjardin, Jérôme ; Dhaenens, Maarten ; Marks, Hendrik - \ 2019
    Cell Stem Cell 24 (2019)1. - ISSN 1934-5909 - p. 123 - 137.e8.
    chromatin profiling - embryonic stem cells - epigenetics - ground-state pluripotency - H3K27me3 - histone modifications

    Marks and colleagues use integrative mass spectrometry to profile post-translational histone modifications and the chromatin-associated proteome in ground-state pluripotency. This reveals H3K27me3 and PRC2 as widespread hallmarks on euchromatin and heterochromatin. They show that ubiquitous chromatin-associated PRC2 protects the epigenome from priming, in particular from gaining DNA methylation.

    From sustainable drinking water to tsunami hazards : modelling water science for impact
    He, Xiaogang ; Student, Jillian ; Kroeze, Carolien - \ 2019
    Journal of integrative Environmental Sciences 16 (2019)1. - ISSN 1943-815X - p. 157 - 161.
    Water pollution from food production: lessons for optimistic and optimal solutions
    Li, Ang ; Kroeze, Carolien ; Kahil, Taher ; Ma, Lin ; Strokal, Maryna - \ 2019
    Current Opinion in Environmental Sustainability 40 (2019). - ISSN 1877-3435 - p. 88 - 94.

    Food production is a source of various pollutants in aquatic systems. For example, nutrients are lost from fertilized fields, and pathogens from livestock production. Water pollution may impact society and nature. Large-scale water pollution assessments, however, often focus on single pollutants and not on multiple pollutants simultaneously. This study draws lessons from air pollution control for large-scale water quality assessments, where multi-pollutant approaches are more common. To this end, we present a framework for future water pollution assessments searching for optimistic and optimal solutions. We argue that future studies could shift their focus to better account for societal and economic targets. Participatory approaches can help to ensure the feasibility of future solutions to reduce water pollution from food production.

    Increasing nitrogen export to sea: A scenario analysis for the Indus River
    Wang, Mengru ; Tang, Ting ; Burek, P. ; Havlík, Petr ; Krisztin, Tamás ; Kroeze, Carolien ; Leclère, D. ; Strokal, Maryna ; Wada, Yoshihide ; Wang, Yaoping ; Langan, S. - \ 2019
    Science of the Total Environment 694 (2019). - ISSN 0048-9697
    Indus River - Nitrogen sources - Representative concentration pathways - River export of nitrogen (N) - Shared socio-economic pathways - Sub-basins

    The Indus River Basin faces severe water quality degradation because of nutrient enrichment from human activities. Excessive nutrients in tributaries are transported to the river mouth, causing coastal eutrophication. This situation may worsen in the future because of population growth, economic development, and climate change. This study aims at a better understanding of the magnitude and sources of current (2010) and future (2050) river export of total dissolved nitrogen (TDN) by the Indus River at the sub-basin scale. To do this, we implemented the MARINA 1.0 model (Model to Assess River Inputs of Nutrients to seAs). The model inputs for human activities (e.g., agriculture, land use) were mainly from the GLOBIOM (Global Biosphere Management Model) and EPIC (Environmental Policy Integrated Model) models. Model inputs for hydrology were from the Community WATer Model (CWATM). For 2050, three scenarios combining Shared Socio-economic Pathways (SSPs 1, 2 and 3) and Representative Concentration Pathways (RCPs 2.6 and 6.0) were selected. A novelty of this study is the sub-basin analysis of future N export by the Indus River for SSPs and RCPs. Result shows that river export of TDN by the Indus River will increase by a factor of 1.6–2 between 2010 and 2050 under the three scenarios. >90% of the dissolved N exported by the Indus River is from midstream sub-basins. Human waste is expected to be the major source, and contributes by 66–70% to river export of TDN in 2050 depending on the scenarios. Another important source is agriculture, which contributes by 21–29% to dissolved inorganic N export in 2050. Thus a combined reduction in both diffuse and point sources in the midstream sub-basins can be effective to reduce coastal water pollution by nutrients at the river mouth of Indus.

    How to avoid coastal eutrophication - a back-casting study for the North China Plain
    Li, Ang ; Strokal, Maryna ; Bai, Zhaohai ; Kroeze, Carolien ; Ma, Lin - \ 2019
    Science of the Total Environment 692 (2019). - ISSN 0048-9697 - p. 676 - 690.
    China - Coastal eutrophication - Manure management - MARINA 1.0 model - Nutrients - River pollution

    Eutrophication is a serious problem in Chinese seas. We explore possibilities to avoid coastal eutrophication without compromising food production in the North China Plain. We used the Model to Assess River Inputs of Nutrient to seAs (MARINA 1.0) for back-casting and scenario analysis. Avoiding coastal eutrophication by 2050 implies required reductions in river export of total nitrogen (TN) and phosphorus (TP) by 50–90% for the Hai, Huai and Huang rivers. We analyzed the potential to meet these targets in 54 scenarios assuming improvements in manure recycling, fertilizer application, animal feed and wastewater treatment. Results indicate that combining manure recycling while reducing synthetic fertilizer use are effective options to reduce nutrient inputs to seas. Without such options, direct discharge of manure are important sources of water pollution. In the 7–25 scenarios with the low eutrophication potential, 40–100% of the N and P in untreated manure is recycled on land to replace synthetic fertilizers. Our results can support the formulation of effective environmental policies to avoid coastal eutrophication in China.

    Multi-scale Modeling of Nutrient Pollution in the Rivers of China
    Chen, Xi ; Strokal, Maryna ; Vliet, Michelle T.H. Van; Stuiver, John ; Wang, Mengru ; Bai, Zhaohai ; Ma, Lin ; Kroeze, Carolien - \ 2019
    Environmental Science and Technology 53 (2019)16. - ISSN 0013-936X - p. 9614 - 9625.
    Chinese surface waters are severely polluted by nutrients. This study addresses three challenges in nutrient modeling for rivers in China: (1) difficulties in transferring modeling results across biophysical and administrative scales, (2) poor representation of the locations of point sources, and (3) limited incorporation of the direct discharge of manure to rivers. The objective of this study is, therefore, to quantify inputs of nitrogen (N) and phosphorus (P) to Chinese rivers from different sources at multiple scales. We developed a novel multi-scale modeling approach including a detailed, state-of-the-art representation of point sources of nutrients in rivers. The model results show that the river pollution and source attributions differ among spatial scales. Point sources accounted for 75% of the total dissolved phosphorus (TDP) inputs to rivers in China in 2012, and diffuse sources accounted for 72% of the total dissolved nitrogen (TDN) inputs. One-third of the sub-basins accounted for more than half of the pollution. Downscaling to the smallest scale (polygons) reveals that 14% and 9% of the area contribute to more than half of the calculated TDN and TDP pollution, respectively. Sources of pollution vary considerably among and within counties. Clearly, multi-scale modeling may help to develop effective policies for water pollution
    Impact hotspots of reduced nutrient discharge shift across the globe with population and dietary changes
    Wang, Xu ; Daigger, Glen ; Vries, Wim de; Kroeze, Carolien ; Yang, Min ; Ren, Nan Qi ; Liu, Junxin ; Butler, David - \ 2019
    Nature Communications 10 (2019)1. - ISSN 2041-1723

    Reducing nutrient discharge from wastewater is essential to mitigating aquatic eutrophication; however, energy- and chemicals-intensive nutrient removal processes, accompanied with the emissions of airborne contaminants, can create other, unexpected, environmental consequences. Implementing mitigation strategies requires a complete understanding of the effects of nutrient control practices, given spatial and temporal variations. Here we simulate the environmental impacts of reducing nutrient discharge from domestic wastewater in 173 countries during 1990–2050. We find that improvements in wastewater infrastructure achieve a large-scale decline in nutrient input to surface waters, but this is causing detrimental effects on the atmosphere and the broader environment. Population size and dietary protein intake have the most significant effects over all the impacts arising from reduction of wastewater nutrients. Wastewater-related impact hotspots are also shifting from Asia to Africa, suggesting a need for interventions in such countries, mostly with growing populations, rising dietary intake, rapid urbanisation, and inadequate sanitation.

    Seasonality in river export of nitrogen : A modelling approach for the Yangtze River
    Chen, Xuanjing ; Strokal, Maryna ; Kroeze, Carolien ; Ma, Lin ; Shen, Zhenyao ; Wu, Jiechen ; Chen, Xinping ; Shi, Xiaojun - \ 2019
    Science of the Total Environment 671 (2019). - ISSN 0048-9697 - p. 1282 - 1292.
    Diffuse and point sources - MARINA model - Nitrogen - Sub-basins - Water quality - Yangtze River

    In China, many estuaries suffer from eutrophication problems such as green tides and hypoxia. This is often a result of human activities on land leading to increased nutrient exports by rivers. River pollution shows seasonal trends that are not well understood. Therefore, the main objective of this study is to improve our understanding of the seasonal variation in river export of dissolved inorganic nitrogen (DIN) by source and at the sub-basin scale. To this end, we modified the existing MARINA model 1.0 (Model to Assess River Input of Nutrient to seAs) to account for seasonality in river export of DIN, and applied it to the Yangtze River. The resulting MARINA model version 1.1 takes a mass-balance approach and accounts for seasonality in human activities (e.g., crop planting and fertilization) and meteorology. The model distinguishes four seasons: winter (December–February), spring (March–May), summer (June–August) and fall (September–November). Our results for Yangtze indicate that N inputs to land and river export of DIN to sea are higher in summer and lower in winter. In spring, summer and fall, diffuse sources from agriculture contribute 43–85% to DIN export. In spring and fall, use of synthetic N fertilizers in cropland is an important source of DIN. In summer, both atmospheric N deposition and synthetic N fertilizers dominate. Animal manure is typically applied on land in spring and fall, contributing then to DIN. In winter, point sources of animal manure are responsible for 34–74% of DIN river export. In general, more DIN is exported to the sea from activities in middlestream and downstream sub-basins. Our results can serve as an example for other large rivers worldwide, and support the formulation of effective strategies to reduce seasonal eutrophication.

    Re-evaluating safety risks of multifunctional dikes with a probabilistic risk framework
    Marijnissen, Richard ; Kok, Matthijs ; Kroeze, Carolien ; Loon-Steensma, Jantsje Van - \ 2019
    Natural Hazards and Earth System Sciences 19 (2019)4. - ISSN 1561-8633 - p. 737 - 756.

    It is not uncommon for a flood defence to be combined with other societal uses as a multifunctional flood defence, from housing in urban areas to nature conservation in rural areas. The assessment of the safety of multifunctional flood defences is often done using conservative estimates. This study synthesizes new probabilistic approaches to evaluate the safety of multifunctional flood defences employed in the Netherlands and explores the results of these approaches. In this paper a case representing a typical Dutch river dike combining a flood safety function with a nature and housing function is assessed by its probability of failure for multiple reinforcement strategies considering multiple relevant failure mechanisms. Results show how the conservative estimates of multifunctional flood defences lead to a systematic underestimation of the reliability of these dikes. Furthermore, in a probabilistic assessment uncertainties introduced by multifunctional elements affect the level of safety of the dike proportional to the reliability of the dike itself. Hence, dikes with higher protection levels are more suitable to be combined with potentially harmful uses for safety, whereas dikes with low protection levels can benefit most from uses that contribute to safety.

    Modelling global river export of microplastics to the marine environment : Sources and future trends
    Wijnen, Jikke van; Ragas, Ad M.J. ; Kroeze, Carolien - \ 2019
    Science of the Total Environment 673 (2019). - ISSN 0048-9697 - p. 392 - 401.
    Coastal seas - Future scenarios - GREMiS model - Microplastics - Plastic soup - River transport

    Microplastics, transported by rivers to oceans, are triggering environmental concern. This study aims to better understand river export of microplastics from land to sea. We developed the Global Riverine Export of Microplastics into Seas (GREMiS) model, a global, spatially explicit model for analysing the annual microplastics export to coastal seas. Our results indicate that riverine microplastics export varies among world regions, with several hotspots, e.g., South East Asia, and, depending on the 2050 scenario, may be doubled (‘Business as usual’) or halved due to improved waste management (‘Environment profits’). Globally, our model simulations indicated fragmentation of macroplastics as the main source of microplastics, but this result heavily depends on the assumed fragmentation rate. Sewerage discharges contributed only 20%, ranging from 1% (Africa) to 60% (OECD countries) and decreasing by 2050 as a result of improved sanitation. We conclude that, combating microplastics in the aquatic environment requires more region-specific analyses.

    Scenarios for withdrawal of oil palm plantations from peatlands in Jambi Province, Sumatra, Indonesia
    Afriyanti, Dian ; Hein, Lars ; Kroeze, Carolien ; Zuhdi, Mohammad ; Saad, Asmadi - \ 2019
    Regional Environmental Change 19 (2019)4. - ISSN 1436-3798 - p. 1201 - 1215.
    Carbon emission - Mitigation - Oil palm - Peatlands - Restore - Withdrawal
    In Indonesia, peatlands are still being converted into oil palm plantations. The associated fires and peat oxidation result in smoke and large carbon emissions. In the medium term, peatlands should be used for production systems that do not require (or require much less) drainage. In this context, this study aims to explore scenarios for the withdrawal of oil palm plantations from peatlands in Jambi province and the associated carbon emissions in the coming decades. We first analyzed past land-use change trends in Jambi peatlands. Then, we analyzed three scenarios for the future: (1) a baseline scenario, assuming further expansions by smallholders, but not by companies, (2) a scenario assuming withdrawal from peat by companies only, and (3) a scenario assuming withdrawal from peat by companies and smallholders. In both scenarios 1 and 2, it is assumed smallholders keep on expanding oil palm plantations in peatlands up to 2020 but not thereafter. To accommodate economic interests of growers, withdrawal of oil palm plantations is assumed to only take place when the palm trees are 25 years old and their productivity starts declining. Our study shows that there has been a rapid expansion of oil palm plantations in peatlands of Jambi from 30,000 ha in 1987 to 483,000 ha in 2014. In our baseline scenario, involving commitments from companies but not from smallholders, the area of oil palm further increases by 20% between 2014 and 2040; this implies that by 2040, almost all peatlands, including those in the buffer zone of Berbak National Park, will have been converted to plantations. The corresponding greenhouse gas emissions are 53 Mt CO 2 -equivalent per year (from both peat decomposition and fires). In the scenario assuming withdrawal of company plantations from peatlands, the plantation area will be reduced to half that in the baseline scenario in 2040. This would decrease CO 2 -equivalent emissions in 2040 to below 2010 levels (27.9 Mt per year). Our study shows that a substantial decrease in emissions is only possible in scenario 3 with an almost full withdrawal of plantations from peatlands by 2040. This reduces CO 2 -equivalent emissions to the level of 2000 (4.3 Mt per year) and leads to safeguarding the remaining pristine peat swamp forest in Berbak National Park.
    Editorial overview : Water quality: A new challenge for global scale model development and application
    Hofstra, Nynke ; Kroeze, Carolien ; Flörke, Martina ; Vliet, Michelle T.H. van - \ 2019
    Current Opinion in Environmental Sustainability 36 (2019). - ISSN 1877-3435 - p. A1 - A5.
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