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BG | Volume 16, issue 14
Biogeosciences, 16, 2821–2836, 2019
https://doi.org/10.5194/bg-16-2821-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-16-2821-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
Special issue: Biogeochemical processes in highly dynamic peat-draining rivers...
Biogeosciences, 16, 2821–2836, 2019
https://doi.org/10.5194/bg-16-2821-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-16-2821-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article 18 Jul 2019
Research article | 18 Jul 2019
Dissolved inorganic nitrogen in a tropical estuary in Malaysia: transport and transformation
Shan Jiang et al.Related authors
Ying Wu, Kun Zhu, Jing Zhang, Moritz Müller, Shan Jiang, Aazani Mujahid, Mohd Fakharuddin Muhamad, and Edwin Sien Aun Sia
Biogeosciences, 16, 4517–4533, https://doi.org/10.5194/bg-16-4517-2019, https://doi.org/10.5194/bg-16-4517-2019, 2019
Short summary
Short summary
Our understanding of terrestrial organic matter (TOM) in tropical peat-draining rivers remains limited, especially in Southeast Asia. We explored the characteristics of TOM via bulk parameters and lignin phenols of sediment in Malaysia. This showed that the most important plant source of the organic matter in these rivers is woody angiosperm C3 plants with limited diagenetic alteration. This slower degradation of TOM may be a link to higher total nitrogen content, especially for the small river.
Yan Chang, Moritz Müller, Ying Wu, Shan Jiang, Wan wan Cao, Jian guo Qu, Jing ling Ren, Xiaona Wang, En ming Rao, Xiao lu Wang, Aazani Mujahid, Mohd Fakharuddin Muhamad, Edwin Sia Sien Aun, Faddrine Holt Ajon Jang, and Jing Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-233, https://doi.org/10.5194/bg-2019-233, 2019
Revised manuscript under review for BG
Short summary
Short summary
Se is an essential micronutrient for many organisms. Our knowledge of dissolved Se biogeochemical cycling in tropical estuaries is very limited. We have found that the dissolved organic selenium was the major speciation in the peat-draining rivers and estuaries. The DOSe fractions may be associated with high-molecular-weight peatland-derived carbon compounds and may photodegrade to more bioavailable forms once transported to oligotrophic coastal water, where they may promote productivity.
Zhuoyi Zhu, Joanne Oakes, Bradley Eyre, Youyou Hao, Edwin Sien Aun Sia, Shan Jiang, Moritz Müller, and Jing Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-157, https://doi.org/10.5194/bg-2019-157, 2019
Revised manuscript under review for BG
Short summary
Short summary
Samples were collected in August 2016 in the Rajang river and estuary, with tropical forest in its river basin and peatland in the estuary. Organic matter composition was influenced by transportation in the river basin, whereas peatland can added clear bio-degraded part to the fluvial organic matter, which implies modification of the initial lability and/or starting points in subsequent degradation/alternation process after the organic matter entering into the sea.
Xiaohui Zhang, Moritz Müller, Shan Jiang, Ying Wu, Xunchi Zhu, Aazani Mujahid, Zhuoyi Zhu, Mohd Fakharuddin Muhamad, Edwin Sien Aun Sia, Faddrine Holt Ajon Jang, and Jing Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-204, https://doi.org/10.5194/bg-2019-204, 2019
Revised manuscript under review for BG
Short summary
Short summary
This study offered detailed information on dFe concentrations, distribution and the magnitude of flux in the Rajang River, i.e. the largest river in Malaysia. Three blackwater rivers, draining from peatlands, were also included in our study. Compared with the Rajang River, the dFe concentrations and yield from three blackwater rivers were much higher. Anthropogenic activities in the watershed, such as palm oil plantation, may markedly increase the concentration dFe in these tropical rivers.
Ying Wu, Kun Zhu, Jing Zhang, Moritz Müller, Shan Jiang, Aazani Mujahid, Mohd Fakharuddin Muhamad, and Edwin Sien Aun Sia
Biogeosciences, 16, 4517–4533, https://doi.org/10.5194/bg-16-4517-2019, https://doi.org/10.5194/bg-16-4517-2019, 2019
Short summary
Short summary
Our understanding of terrestrial organic matter (TOM) in tropical peat-draining rivers remains limited, especially in Southeast Asia. We explored the characteristics of TOM via bulk parameters and lignin phenols of sediment in Malaysia. This showed that the most important plant source of the organic matter in these rivers is woody angiosperm C3 plants with limited diagenetic alteration. This slower degradation of TOM may be a link to higher total nitrogen content, especially for the small river.
Hermann W. Bange, Chun Hock Sim, Daniel Bastian, Jennifer Kallert, Annette Kock, Aazani Mujahid, and Moritz Müller
Biogeosciences, 16, 4321–4335, https://doi.org/10.5194/bg-16-4321-2019, https://doi.org/10.5194/bg-16-4321-2019, 2019
Short summary
Short summary
Nitrous oxide (N2O) and methane (CH4) are atmospheric trace gases which play important roles in the climate and atmospheric chemistry of the Earth. However, little is known about their emissions from rivers and estuaries. To this end, concentrations of N2O and CH4 were measured during a seasonal study in six rivers and estuaries in northwestern Borneo. The concentrations of both gases were mainly driven by rainfall. The rivers and estuaries were an overall net source of atmospheric N2O and CH4.
Edwin Sien Aun Sia, Zhuoyi Zhu, Jing Zhang, Wee Cheah, Shan Jiang, Faddrine Holt Jang, Aazani Mujahid, Fuh-Kwo Shiah, and Moritz Müller
Biogeosciences, 16, 4243–4260, https://doi.org/10.5194/bg-16-4243-2019, https://doi.org/10.5194/bg-16-4243-2019, 2019
Short summary
Short summary
Microbial community composition and diversity in freshwater habitats are much less studied compared to marine and soil communities. This study presents the first assessment of microbial communities of the Rajang River, the longest river in Malaysia, expanding our knowledge of microbial ecology in tropical regions. Areas surrounded by oil palm plantations showed the lowest diversity and other signs of anthropogenic impacts included the presence of CFB groups as well as probable algal blooms.
Yan Chang, Moritz Müller, Ying Wu, Shan Jiang, Wan wan Cao, Jian guo Qu, Jing ling Ren, Xiaona Wang, En ming Rao, Xiao lu Wang, Aazani Mujahid, Mohd Fakharuddin Muhamad, Edwin Sia Sien Aun, Faddrine Holt Ajon Jang, and Jing Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-233, https://doi.org/10.5194/bg-2019-233, 2019
Revised manuscript under review for BG
Short summary
Short summary
Se is an essential micronutrient for many organisms. Our knowledge of dissolved Se biogeochemical cycling in tropical estuaries is very limited. We have found that the dissolved organic selenium was the major speciation in the peat-draining rivers and estuaries. The DOSe fractions may be associated with high-molecular-weight peatland-derived carbon compounds and may photodegrade to more bioavailable forms once transported to oligotrophic coastal water, where they may promote productivity.
Zhuoyi Zhu, Joanne Oakes, Bradley Eyre, Youyou Hao, Edwin Sien Aun Sia, Shan Jiang, Moritz Müller, and Jing Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-157, https://doi.org/10.5194/bg-2019-157, 2019
Revised manuscript under review for BG
Short summary
Short summary
Samples were collected in August 2016 in the Rajang river and estuary, with tropical forest in its river basin and peatland in the estuary. Organic matter composition was influenced by transportation in the river basin, whereas peatland can added clear bio-degraded part to the fluvial organic matter, which implies modification of the initial lability and/or starting points in subsequent degradation/alternation process after the organic matter entering into the sea.
Yongli Zhou, Patrick Martin, and Moritz Müller
Biogeosciences, 16, 2733–2749, https://doi.org/10.5194/bg-16-2733-2019, https://doi.org/10.5194/bg-16-2733-2019, 2019
Short summary
Short summary
We found that peatlands in coastal Sarawak, Borneo, export extremely humified organic matter, which dominates the riverine organic matter pool and conservatively mixes with seawater, while the freshly produced fraction is low and stable in concentration at all salinities. We estimated that terrigenous fractions, which showed high photolability, still account for 20 % of the coastal dissolved organic carbon pool, implying the importance of peat-derived organic matter in the coastal carbon cycle.
Edwin Sien Aun Sia, Jing Zhang, Shan Jiang, Zhuoyi Zhu, Gonzalo Carrasco, Faddrine Holt Jang, Aazani Mujahid, and Moritz Müller
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-219, https://doi.org/10.5194/bg-2019-219, 2019
Revised manuscript under review for BG
Short summary
Short summary
Nutrient loads carried by large rivers and discharged into the continental shelf and coastal waters are vital to support primary production. Our knowledge of tropical river systems is fragmented with very few seasonal studies available for Southeast Asia (SEA). We present data from three sampling campaigns on the longest river in Malaysia, the Rajang river. Our results show the generalization of SEA as a nutrient hotspot might not hold true for all regions and requires further investigation.
Xiaohui Zhang, Moritz Müller, Shan Jiang, Ying Wu, Xunchi Zhu, Aazani Mujahid, Zhuoyi Zhu, Mohd Fakharuddin Muhamad, Edwin Sien Aun Sia, Faddrine Holt Ajon Jang, and Jing Zhang
Biogeosciences Discuss., https://doi.org/10.5194/bg-2019-204, https://doi.org/10.5194/bg-2019-204, 2019
Revised manuscript under review for BG
Short summary
Short summary
This study offered detailed information on dFe concentrations, distribution and the magnitude of flux in the Rajang River, i.e. the largest river in Malaysia. Three blackwater rivers, draining from peatlands, were also included in our study. Compared with the Rajang River, the dFe concentrations and yield from three blackwater rivers were much higher. Anthropogenic activities in the watershed, such as palm oil plantation, may markedly increase the concentration dFe in these tropical rivers.
Tim Rixen, Birgit Gaye, Kay-Christian Emeis, and Venkitasubramani Ramaswamy
Biogeosciences, 16, 485–503, https://doi.org/10.5194/bg-16-485-2019, https://doi.org/10.5194/bg-16-485-2019, 2019
Short summary
Short summary
Data obtained from sediment trap experiments in the Indian Ocean indicate that lithogenic matter ballast increases organic carbon flux rates on average by 45 % and by up to 62 % at trap locations in the river-influenced regions of the Indian Ocean. Such a strong lithogenic matter ballast effect implies that land use changes and the associated enhanced transport of lithogenic matter may significantly affect the CO2 uptake of the organic carbon pump in the receiving ocean areas.
Denise Müller-Dum, Thorsten Warneke, Tim Rixen, Moritz Müller, Antje Baum, Aliki Christodoulou, Joanne Oakes, Bradley D. Eyre, and Justus Notholt
Biogeosciences, 16, 17–32, https://doi.org/10.5194/bg-16-17-2019, https://doi.org/10.5194/bg-16-17-2019, 2019
Short summary
Short summary
Southeast Asian peat-draining rivers are potentially strong sources of carbon to the atmosphere due to the large amounts of organic carbon stored in those ecosystems. We present the first assessment of CO2 emissions from the Rajang River, the largest peat-draining river in Malaysia. The peatlands’ influence on the CO2 emissions from the Rajang River was smaller than expected, probably due to their proximity to the coast. Therefore, the Rajang was only a moderate source of CO2 to the atmosphere.
Patrick Martin, Nagur Cherukuru, Ashleen S. Y. Tan, Nivedita Sanwlani, Aazani Mujahid, and Moritz Müller
Biogeosciences, 15, 6847–6865, https://doi.org/10.5194/bg-15-6847-2018, https://doi.org/10.5194/bg-15-6847-2018, 2018
Short summary
Short summary
The carbon cycle is a key control for the Earth's climate. Every year rivers deliver a lot of organic carbon to coastal seas, but we do not know what happens to this carbon, particularly in the tropics. We show that rivers in Borneo deliver carbon from peat swamps to the sea with at most minimal biological or chemical alteration in estuaries, but sunlight can rapidly oxidise this carbon to CO2. This means that south-east Asian seas are likely hotspots of terrestrial carbon decomposition.
Celeste Sánchez-Noguera, Ines Stuhldreier, Jorge Cortés, Carlos Jiménez, Álvaro Morales, Christian Wild, and Tim Rixen
Biogeosciences, 15, 2349–2360, https://doi.org/10.5194/bg-15-2349-2018, https://doi.org/10.5194/bg-15-2349-2018, 2018
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The Papagayo upwelling system is a natural laboratory for studying ecosystems' response to ocean acidification (OA). We measured pH and pCO2 in situ with high temporal resolution and compared them with data available from upwelling season. Local coral reefs are exposed to acidic and undersaturated waters in upwelling and non-upwelling events. These restrictive conditions occur alongside local stressors, potentially decreasing reefs' resilience and increasing their vulnerability under future OA.
Birgit Gaye, Anna Böll, Joachim Segschneider, Nicole Burdanowitz, Kay-Christian Emeis, Venkitasubramani Ramaswamy, Niko Lahajnar, Andreas Lückge, and Tim Rixen
Biogeosciences, 15, 507–527, https://doi.org/10.5194/bg-15-507-2018, https://doi.org/10.5194/bg-15-507-2018, 2018
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The Arabian Sea has one of the most severe oxygen minima of the world's oceans between about 100 and 1200 m of water depth and is therefore a major oceanic nitrogen sink. Stable nitrogen isotopic ratios in sediments record changes in oxygen concentrations and were studied for the last 25 kyr. Oxygen concentrations dropped at the end of the last glacial and became further reduced during the Holocene, probably due to the increasing age of the low-oxygen water mass.
Tim Rixen, Birgit Gaye, Kay-Christian Emeis, and Venkitasubramani Ramaswamy
Biogeosciences Discuss., https://doi.org/10.5194/bg-2017-317, https://doi.org/10.5194/bg-2017-317, 2017
Manuscript not accepted for further review
Short summary
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Sediment trap experiments showed that in the river-influenced regions of the Indian Ocean lithogenic matter supplied from land controls the organic carbon export into the deep sea via its ballast effect in sinking particles. Carbonate produced by plankton is the main ballast material in the open ocean. The ballast effect increases the CO2 uptake of the organic carbon pump by enhancing the amount of nutrients used to bind CO2 and by favouring the sedimentation of organic matter.
Denise Müller, Hermann W. Bange, Thorsten Warneke, Tim Rixen, Moritz Müller, Aazani Mujahid, and Justus Notholt
Biogeosciences, 13, 2415–2428, https://doi.org/10.5194/bg-13-2415-2016, https://doi.org/10.5194/bg-13-2415-2016, 2016
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Estuaries act as sources of the greenhouse gases nitrous oxide (N2O) and methane (CH4) to the atmosphere. We provide first measurements of N2O and CH4 in two estuaries in north-western Borneo, a region which is dominated by peatlands. We show that N2O and CH4 concentrations in these estuaries are moderate despite high organic carbon loads, that nutrient enhancement does not lead to enhanced N2O emissions, and that the wet season dominates the variability of the emissions in these systems.
Zhuo-Yi Zhu, Ying Wu, Su-Mei Liu, Fred Wenger, Jun Hu, Jing Zhang, and Rui-Feng Zhang
Biogeosciences, 13, 975–987, https://doi.org/10.5194/bg-13-975-2016, https://doi.org/10.5194/bg-13-975-2016, 2016
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Svalbard archipelago has lots of valley glaciers, and its position in organic carbon flux to ocean remains unclear. In this work, we found that these valley glaciers have a much higher area-weighted and discharge-weighted organic carbon flux, relative to Greenland Ice Sheet, and are comparable to other valley glaciers like those in the Alaska region. Hence Svalbard glaciers are an important source for terrestrial carbon.
D. Müller, T. Warneke, T. Rixen, M. Müller, A. Mujahid, H. W. Bange, and J. Notholt
Biogeosciences, 13, 691–705, https://doi.org/10.5194/bg-13-691-2016, https://doi.org/10.5194/bg-13-691-2016, 2016
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We studied organic carbon and the dissolved greenhouse gases carbon dioxide (CO2) and carbon monoxide (CO) in two estuaries in Sarawak, Malaysia, whose coast is covered by carbon-rich peatlands. The estuaries received terrestrial organic carbon from peat-draining tributaries. A large fraction was converted to CO2 and a minor fraction to CO. Both gases were released to the atmosphere. This shows how these estuaries function as efficient filters between land and ocean in this important region.
D. Müller, T. Warneke, T. Rixen, M. Müller, S. Jamahari, N. Denis, A. Mujahid, and J. Notholt
Biogeosciences, 12, 5967–5979, https://doi.org/10.5194/bg-12-5967-2015, https://doi.org/10.5194/bg-12-5967-2015, 2015
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Tropical peatlands are an important source of organic carbon to rivers. However, due to the remoteness of these ecosystems, data are scarce. We present the first combined assessment of both lateral organic carbon fluxes and CO2 emissions from an undisturbed tropical peat-draining river. Compared to the organic carbon concentrations, CO2 fluxes to the atmosphere were actually relatively moderate, which we attributed to the short water residence time.
T. Rixen, A. Baum, B. Gaye, and B. Nagel
Biogeosciences, 11, 5733–5747, https://doi.org/10.5194/bg-11-5733-2014, https://doi.org/10.5194/bg-11-5733-2014, 2014
A. Flohr, A. K. van der Plas, K.-C. Emeis, V. Mohrholz, and T. Rixen
Biogeosciences, 11, 885–897, https://doi.org/10.5194/bg-11-885-2014, https://doi.org/10.5194/bg-11-885-2014, 2014
R. H. Li, S. M. Liu, Y. W. Li, G. L. Zhang, J. L. Ren, and J. Zhang
Biogeosciences, 11, 481–506, https://doi.org/10.5194/bg-11-481-2014, https://doi.org/10.5194/bg-11-481-2014, 2014
B. Gaye, B. Nagel, K. Dähnke, T. Rixen, N. Lahajnar, and K.-C. Emeis
Biogeosciences, 10, 7689–7702, https://doi.org/10.5194/bg-10-7689-2013, https://doi.org/10.5194/bg-10-7689-2013, 2013
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Biogeosciences, 16, 1053–1071, https://doi.org/10.5194/bg-16-1053-2019, https://doi.org/10.5194/bg-16-1053-2019, 2019
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Biogeosciences, 16, 289–307, https://doi.org/10.5194/bg-16-289-2019, https://doi.org/10.5194/bg-16-289-2019, 2019
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Ivan V. Krickov, Artem G. Lim, Rinat M. Manasypov, Sergey V. Loiko, Liudmila S. Shirokova, Sergey N. Kirpotin, Jan Karlsson, and Oleg S. Pokrovsky
Biogeosciences, 15, 6867–6884, https://doi.org/10.5194/bg-15-6867-2018, https://doi.org/10.5194/bg-15-6867-2018, 2018
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We tested the effect of climate, permafrost and physio-geographical landscape parameters on particulate C, N and P concentrations in small- and medium- sized rivers in the Western Siberian Lowland (WSL). We discovered a maximum of particulate C and N concentrations at the beginning of the permafrost appearance. A northward shift of permafrost boundaries may increase the particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2.
Wenjing Liu, Zhifang Xu, Huiguo Sun, Tong Zhao, Chao Shi, and Taoze Liu
Biogeosciences, 15, 4955–4971, https://doi.org/10.5194/bg-15-4955-2018, https://doi.org/10.5194/bg-15-4955-2018, 2018
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The southeastern coastal region is the top acid-rain-impacted area in China. It is worth evaluating the acid deposition impacts on chemical weathering and CO2 consumption there. River water geochemistry evidenced an overestimation of CO2 sequestration if H2SO4/HNO3 involvement was ignored, which accounted for 33.6 % of the total flux by silicate weathering in this area. This study quantitatively highlights the anthropogenic acid effects on chemical weathering and associated CO2 consumption.
Thi Phuong Quynh Le, Cyril Marchand, Cuong Tu Ho, Nhu Da Le, Thi Thuy Duong, XiXi Lu, Phuong Kieu Doan, Trung Kien Nguyen, Thi Mai Huong Nguyen, and Duy An Vu
Biogeosciences, 15, 4799–4814, https://doi.org/10.5194/bg-15-4799-2018, https://doi.org/10.5194/bg-15-4799-2018, 2018
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The Red River is a typical south-east Asian river, strongly affected by climate and human activity. This study showed the spatial and seasonal variability of CO2 emissions at the water–air interface of the lower part of this river due to natural conditions (meteo-hydrological-geomorphological characteristics) and human activities (dam impoundment, population, land use). The Red River water was supersaturated with CO2, providing a mean water–air CO2 flux of 530 ± 17 mmol m−2 d−1.
Wei Wen Wong, Jesse Pottage, Fiona Y. Warry, Paul Reich, Keryn L. Roberts, Michael R. Grace, and Perran L. M. Cook
Biogeosciences, 15, 3953–3965, https://doi.org/10.5194/bg-15-3953-2018, https://doi.org/10.5194/bg-15-3953-2018, 2018
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Over-enrichment of nitrate can pose substantial risk to the quality of freshwater ecosystems. Hence, understanding the dynamics of nitrate is the key to better management of waterways. This study evaluates the relationship between the effects of land use and rainfall on the major sources and processing of nitrate within and between five streams in five catchments spanning an agricultural land use gradient. We found that rainfall exerted significant control over the fate of nitrate.
Lishan Ran, Mingyang Tian, Nufang Fang, Suiji Wang, Xixi Lu, Xiankun Yang, and Frankie Cho
Biogeosciences, 15, 3857–3871, https://doi.org/10.5194/bg-15-3857-2018, https://doi.org/10.5194/bg-15-3857-2018, 2018
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We systematically assessed the transport and fate of riverine carbon in the moderate-sized Wuding catchment on the Chinese Loess Plateau by constructing a riverine carbon budget and further relating it to terrestrial ecosystem productivity. The riverine carbon export accounted for 16 % of the catchment's net ecosystem production (NEP). It seems that a significant fraction of terrestrial NEP in this catchment is laterally transported from the terrestrial biosphere to the drainage network.
Robert O. Hall Jr. and Hilary L. Madinger
Biogeosciences, 15, 3085–3092, https://doi.org/10.5194/bg-15-3085-2018, https://doi.org/10.5194/bg-15-3085-2018, 2018
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Streams exchange oxygen with the atmosphere, but this rate is difficult to measure. We added argon to small mountain streams to estimate gas exchange. We compared these rates with sulfur hexafluoride, an intense greenhouse gas. Argon worked well to measure gas exchange, but had higher-than-predicted rates than sulfur hexafluoride. Argon exchange is more likely to represent that for oxygen because they share similar physical properties. We suggest argon to measure gas exchange in small streams.
Ji-Hyung Park, Omme K. Nayna, Most S. Begum, Eliyan Chea, Jens Hartmann, Richard G. Keil, Sanjeev Kumar, Xixi Lu, Lishan Ran, Jeffrey E. Richey, Vedula V. S. S. Sarma, Shafi M. Tareq, Do Thi Xuan, and Ruihong Yu
Biogeosciences, 15, 3049–3069, https://doi.org/10.5194/bg-15-3049-2018, https://doi.org/10.5194/bg-15-3049-2018, 2018
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Human activities are drastically altering water and material flows in river systems across Asia. This review provides a conceptual framework for assessing the human impacts on Asian river C fluxes and an update on anthropogenic alterations of riverine C fluxes, focusing on the impacts of water pollution and river impoundments on CO2 outgassing from the rivers draining South, Southeast, and East Asian regions that account for the largest fraction of river discharge and C exports from Asia.
Chung-Te Chang, Jr-Chuan Huang, Lixin Wang, Yu-Ting Shih, and Teng-Chiu Lin
Biogeosciences, 15, 2379–2391, https://doi.org/10.5194/bg-15-2379-2018, https://doi.org/10.5194/bg-15-2379-2018, 2018
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Our analysis of ion input–output budget illustrates that hydrochemical responses to typhoon storms are distinctly different from those of regular storms. In addition, even mild land use change may have large impacts on nutrient exports/losses. We propose that hydrological models should separate hydrochemical processes into regular and extreme conditions to better capture the whole spectrum of hydrochemical responses to a variety of climate conditions.
Camille Minaudo, Florence Curie, Yann Jullian, Nathalie Gassama, and Florentina Moatar
Biogeosciences, 15, 2251–2269, https://doi.org/10.5194/bg-15-2251-2018, https://doi.org/10.5194/bg-15-2251-2018, 2018
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We developed the model QUALity-NETwork (QUAL-NET) to simulate water quality variations in large drainage networks. This model is accurate enough to represent processes occurring over short periods of time such as storm events and helps to fully understand water quality variations in stream networks in the context of climate change and varying human pressures. It was tested on the Loire River and provided good performances and a new understanding of the functioning of the river.
Michael P. Schwab, Julian Klaus, Laurent Pfister, and Markus Weiler
Biogeosciences, 15, 2177–2188, https://doi.org/10.5194/bg-15-2177-2018, https://doi.org/10.5194/bg-15-2177-2018, 2018
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We studied the diel fluctuations of dissolved organic carbon (DOC) concentrations in a small stream in Luxembourg. We identified an increased proportion of DOC from terrestrial sources as responsible for the peaks in DOC in the afternoon. Warmer water temperatures in the riparian zone in the afternoon increased the amount of water flowing towards the stream. Consequently, an increased amount of DOC-rich water from the riparian zone was entering the stream.
Trent R. Marwick, Fredrick Tamooh, Bernard Ogwoka, Alberto V. Borges, François Darchambeau, and Steven Bouillon
Biogeosciences, 15, 1683–1700, https://doi.org/10.5194/bg-15-1683-2018, https://doi.org/10.5194/bg-15-1683-2018, 2018
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A 2-year biogeochemical record provides annual sediment and element flux estimates for the non-dammed Sabaki River, Kenya, establishing a baseline for future research in light of impending construction of the first major upstream reservoir. Over 80 % of material fluxes occur across the wet season, with annual yields comparable to the adjacent, and dammed, Tana River. Observations at low-flow periods suggest large mammalian herbivores may be vectors of terrestrial subsidies to the water column.
Loris Deirmendjian, Denis Loustau, Laurent Augusto, Sébastien Lafont, Christophe Chipeaux, Dominique Poirier, and Gwenaël Abril
Biogeosciences, 15, 669–691, https://doi.org/10.5194/bg-15-669-2018, https://doi.org/10.5194/bg-15-669-2018, 2018
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Carbon leaching to streams represents a very small (~ 2 %) fraction of forest net ecosystem exchange (NEE). Such weak export of carbon from forest ecosystems, at least in temperate regions, is at odds with recent studies that attempt to integrate the contribution of inland waters in the continent carbon budget. Understanding why local and global carbon mass balances strongly diverge on the proportion of land NEE exported to aquatic systems is a major challenge for research in this field.
Katrin Magin, Celia Somlai-Haase, Ralf B. Schäfer, and Andreas Lorke
Biogeosciences, 14, 5003–5014, https://doi.org/10.5194/bg-14-5003-2017, https://doi.org/10.5194/bg-14-5003-2017, 2017
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We analyzed the relationship between terrestrial net primary production (NPP) and the rate at which carbon is exported from catchments in a temperate stream network. The carbon exported by streams and rivers corresponds to 2.7 % of the terrestrial NPP. CO2 evasion and downstream transport contribute about equally to this flux. A review of existing studies suggests that the catchment-specific carbon export varies in a relatively narrow range across different study regions and spatial scales.
Rémi Dupas, Andreas Musolff, James W. Jawitz, P. Suresh C. Rao, Christoph G. Jäger, Jan H. Fleckenstein, Michael Rode, and Dietrich Borchardt
Biogeosciences, 14, 4391–4407, https://doi.org/10.5194/bg-14-4391-2017, https://doi.org/10.5194/bg-14-4391-2017, 2017
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Carbon and nutrient export regimes were analyzed from archetypal headwater catchments to
downstream reaches. In headwater catchments, land use and lithology determine
land-to-stream C, N and P transfer processes. The crucial role of riparian
zones in C, N and P coupling was investigated. In downstream reaches,
point-source contributions and in-stream processes alter C, N and P export
regimes.
Rose M. Smith, Sujay S. Kaushal, Jake J. Beaulieu, Michael J. Pennino, and Claire Welty
Biogeosciences, 14, 2831–2849, https://doi.org/10.5194/bg-14-2831-2017, https://doi.org/10.5194/bg-14-2831-2017, 2017
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Urban streams receive excess nitrogen from numerous sources. We hypothesized that variations in carbon availability and subsurface infrastructure influence emissions of N2O and other greenhouse gases (CH4 and CO2) as excess N is utilized by microbes. We sampled eight streams draining four categories of stormwater and sanitary infrastructure. Dissolved nitrogen concentration was the strongest predictor of CO2 and N2O concentrations, while C : N ratio was the strongest predictor of CH4 in streams.
Benjamin Kupilas, Daniel Hering, Armin W. Lorenz, Christoph Knuth, and Björn Gücker
Biogeosciences, 14, 1989–2002, https://doi.org/10.5194/bg-14-1989-2017, https://doi.org/10.5194/bg-14-1989-2017, 2017
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Modern ecosystem restoration should consider a wide range of environmental characteristics, including functional ones, such as rates and patterns of ecosystem metabolism. We show that hydromorphological river restoration enhanced habitat availability and abundance of macrophytes, promoting river primary productivity and respiration. Incorporating ecosystem functioning into monitoring programs enables a more holistic assessment of river health and a better understanding of restoration effects.
Julia Vanessa Kunz, Michael D. Annable, Jaehyun Cho, Wolf von Tümpling, Kirk Hatfield, Suresh Rao, Dietrich Borchardt, and Michael Rode
Biogeosciences, 14, 631–649, https://doi.org/10.5194/bg-14-631-2017, https://doi.org/10.5194/bg-14-631-2017, 2017
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The hyporheic zone, the subsurface region of streams, is a key compartment for in-stream nutrient retention. Knowledge on actual hyporheic processing rates is still limited due to methodological restrictions which are mainly related to the high local and temporal variability of subsurface flow patterns and nutrient transformation processes. We present a new device which allows quantitative assessment of hyporheic nutrient fluxes and demonstrate its advantages in an exemplary field testing.
Jemma Louise Wadham, Jonathan Hawkings, Jon Telling, Dave Chandler, Jon Alcock, Emily O'Donnell, Preeti Kaur, Elizabeth Bagshaw, Martyn Tranter, Andre Tedstone, and Peter Nienow
Biogeosciences, 13, 6339–6352, https://doi.org/10.5194/bg-13-6339-2016, https://doi.org/10.5194/bg-13-6339-2016, 2016
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Fjord and continental shelf environments in the polar regions are host to some of the planet's most productive ecosystems and support economically important fisheries. A key limiting nutrient for many of these marine phytoplankton is nitrogen. Here we evaluate the potential for a melting Greenland Ice Sheet to supply nitrogen to Arctic coastal ecosystems. We show nitrogen fluxes of a similar order of magnitude to one large Arctic river but yields that are double those typical of Arctic rivers.
Mi-Hee Lee, Jean-Lionel Payeur-Poirier, Ji-Hyung Park, and Egbert Matzner
Biogeosciences, 13, 5421–5432, https://doi.org/10.5194/bg-13-5421-2016, https://doi.org/10.5194/bg-13-5421-2016, 2016
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Heavy storm events may increase the organic matter fluxes from forested watersheds and deteriorate water quality. Our study in two forested watershed in Korea revealed, that a larger proportion of coniferous forests likely leads to less organic carbon and larger of inorganic nitrogen fluxes to the receiving surface water bodies. More severe monsoon storms in the future will increase the fluxes of dissolved organic matter.
Thibault Lambert, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 5405–5420, https://doi.org/10.5194/bg-13-5405-2016, https://doi.org/10.5194/bg-13-5405-2016, 2016
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This paper aims to investigate the spatial variability in dissolved organic matter (DOM) in terms of both concentration and composition in the Congo River network. Stable carbon isotopes and absorption and fluorescent properties of DOM were used as proxies for DOM composition. This study shows that DOM degradation within the Congo Basin results in the transition from aromatic to aliphatic DOM as well as the role of landscape and water residence time on this transition.
Tae Kyung Yoon, Hyojin Jin, Neung-Hwan Oh, and Ji-Hyung Park
Biogeosciences, 13, 3915–3930, https://doi.org/10.5194/bg-13-3915-2016, https://doi.org/10.5194/bg-13-3915-2016, 2016
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Spray- and marble-type equilibrators and a membrane-enclosed CO2 sensor were compared to assess their suitability for continuous pCO2 measurements in inland waters. The results suggest that the fast response of the equilibration systems facilitates capturing large spatial variations in pCO2 during short underway measurements. The membrane-enclosed sensor would be suitable for long-term continuous measurements if biofouling could be overcome by antifouling measures such as copper mesh coverings.
Hongbing Ji, Cai Li, Huaijian Ding, and Yang Gao
Biogeosciences, 13, 3687–3699, https://doi.org/10.5194/bg-13-3687-2016, https://doi.org/10.5194/bg-13-3687-2016, 2016
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The mineral composition, C / N ratios as well as 13C and 15N, of POC was firstly analyzed in suspended and surface sediments in the Wujiang River after the Three Gorges Dam began impounding sediment in 2004. A comparison of POC yield was made between karstic rivers and non-karstic rivers to evaluate the influence of carbonate distribution on POC transport. Considering the cascade reservoir and climate in the Wujiang River, the impacts of reservoirs and extreme drought were estimated in this study.
Johanna I. F. Slaets, Petra Schmitter, Thomas Hilger, Tran Duc Vien, and Georg Cadisch
Biogeosciences, 13, 3267–3281, https://doi.org/10.5194/bg-13-3267-2016, https://doi.org/10.5194/bg-13-3267-2016, 2016
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Maize production on steep slopes causes erosion. Where the eroded material ends up is not well understood. This study assessed transport of sediment in mountainous Vietnam, where maize is cultivated on slopes and rice is cultivated in valleys. Per year, 64 tons per hectare of sediments are brought into the rice fields and 28 tons of those are deposited there. The sediment fraction captured by the paddies is mostly sandy, while fertile silt and clay are exported. Upland erosion thus impacts rice production.
Thibault Lambert, Cristian R. Teodoru, Frank C. Nyoni, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 2727–2741, https://doi.org/10.5194/bg-13-2727-2016, https://doi.org/10.5194/bg-13-2727-2016, 2016
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This manuscript presents a detailed analysis of transport and transformation of dissolved organic matter along the Zambezi River and its largest tributary. A particular focus is put on the effects of floodplains/wetlands and reservoirs as well as low-flow vs. high-flow conditions on the longitudinal patterns in DOM concentration and composition. It is the first study to present such a detailed analysis for a whole, large river system, and in particular for a tropical river other than the Amazon.
Arthur H. W. Beusen, Alexander F. Bouwman, Ludovicus P. H. Van Beek, José M. Mogollón, and Jack J. Middelburg
Biogeosciences, 13, 2441–2451, https://doi.org/10.5194/bg-13-2441-2016, https://doi.org/10.5194/bg-13-2441-2016, 2016
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Intensifying anthropogenic activity over the 20th century including agriculture, water consumption, urbanization, and aquaculture has almost doubled the global nitrogen (N) and phosphorus (P) delivery to streams and steadily increased the N : P ratio in freshwater bodies. Concurrently, the cumulative number of reservoirs has driven a rise in freshwater nutrient retention and removal. Still, river nutrient transport to the ocean has also nearly doubled, potentially stressing coastal environments.
Karen E. Frey, William V. Sobczak, Paul J. Mann, and Robert M. Holmes
Biogeosciences, 13, 2279–2290, https://doi.org/10.5194/bg-13-2279-2016, https://doi.org/10.5194/bg-13-2279-2016, 2016
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In this study, we provide new findings with regards to the spatial distribution of dissolved organic matter (DOM) concentration, bioavailability, and optical properties during mid-summer hydrologic conditions throughout the Kolyma River basin in northeast Siberia. This is particularly critical for this region, where the future fate of organic carbon currently frozen in permafrost soils (and whether it ultimately is released as CO2 and CH4) is tightly linked to the lability of this material.
Oleg S. Pokrovsky, Rinat M. Manasypov, Sergey V. Loiko, Ivan A. Krickov, Sergey G. Kopysov, Larisa G. Kolesnichenko, Sergey N. Vorobyev, and Sergey N. Kirpotin
Biogeosciences, 13, 1877–1900, https://doi.org/10.5194/bg-13-1877-2016, https://doi.org/10.5194/bg-13-1877-2016, 2016
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Climate change in western Siberia and permafrost boundary migration will essentially affect the elements controlled by underground water feeding (DIC, alkaline earth elements (Ca, Sr), oxyanions (Mo, Sb, As) and U). The thickening of the active layer may increase the export of trivalent and tetravalent hydrolysates in the form of organo-ferric colloids.
Jr-Chuan Huang, Tsung-Yu Lee, Teng-Chiu Lin, Thomas Hein, Li-Chin Lee, Yu-Ting Shih, Shuh-Ji Kao, Fuh-Kwo Shiah, and Neng-Huei Lin
Biogeosciences, 13, 1787–1800, https://doi.org/10.5194/bg-13-1787-2016, https://doi.org/10.5194/bg-13-1787-2016, 2016
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The mean riverine DIN export of 49 watersheds in Taiwan is ∼ 3800 kg N km−2 yr−1, 18 times the global average. The mean riverine DIN export ratio is 0.30–0.51, which is much higher than the average of 0.20–0.25 of large rivers around the world, indicating excessive N input relative to ecosystem retention capacity. The DIN export ratio is positively related to agriculture input, and levels of human disturbance and watersheds with high DIN export ratios are likely at advanced stages of N excess.
Michael N. Gooseff, David Van Horn, Zachary Sudman, Diane M. McKnight, Kathleene A. Welch, and William B. Lyons
Biogeosciences, 13, 1723–1732, https://doi.org/10.5194/bg-13-1723-2016, https://doi.org/10.5194/bg-13-1723-2016, 2016
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The landscape of the McMurdo Dry Valleys, Antarctica has been considered quite stable. In 2012, we discovered extensive permafrost degradation along several km of Crescent Stream. Here we document the responses to water quality, specifically changes to dissolved major ion and suspended sediment characteristics. Stream nitrate concentrations were greater than observed in the stream over the previous ~ 20 years, suggesting potentially significant impacts for stream and downstream lake ecosystems.
C. E. M. Lloyd, K. Michaelides, D. R. Chadwick, J. A. J. Dungait, and R. P. Evershed
Biogeosciences, 13, 551–566, https://doi.org/10.5194/bg-13-551-2016, https://doi.org/10.5194/bg-13-551-2016, 2016
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Our interdisciplinary research brings together methodologies from hydrology, soil science and biogeochemistry to address key questions about the transport of cattle slurry in the environment. The paper provides a novel approach to trace dissolved and particulate components of cattle slurry through an experimental hillslope system. This work provides one of the first examples of using biomarkers to assess the effects of slope gradient and rainfall intensity on the movement of slurry derived-OM.
N. Geeraert, F. O. Omengo, G. Govers, and S. Bouillon
Biogeosciences, 13, 517–525, https://doi.org/10.5194/bg-13-517-2016, https://doi.org/10.5194/bg-13-517-2016, 2016
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Rivers transport a large amount of carbon as dissolved organic carbon (DOC). Our incubation experiments on water of the Tana River, Kenya, showed that microbial decomposition of 10–60 % of the initial DOC occurred within the first 24–48 h. Simultaneously, there was a decrease in isotopic composition, indicating that DOC derived from C4 vegetation is preferentially decomposed. This has implications for the assessment of vegetation in a catchment based on isotope signatures of riverine carbon.
J. Temnerud, C. von Brömssen, J. Fölster, I. Buffam, J.-O. Andersson, L. Nyberg, and K. Bishop
Biogeosciences, 13, 399–413, https://doi.org/10.5194/bg-13-399-2016, https://doi.org/10.5194/bg-13-399-2016, 2016
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In this study we test whether river outlet chemistry can be used as an additional source of information to improve the prediction of the total organic carbon (TOC) of headwaters, relative to models based on map information alone. Including river outlet TOC as a predictor in the models gave 5-15 % lower prediction errors than using map information alone. Thus, data on water chemistry measured at river outlets offer information which can complement GIS-based modelling of headwaters chemistry.
A. Hartmann, J. Kobler, M. Kralik, T. Dirnböck, F. Humer, and M. Weiler
Biogeosciences, 13, 159–174, https://doi.org/10.5194/bg-13-159-2016, https://doi.org/10.5194/bg-13-159-2016, 2016
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We consider the time period before and after a wind disturbance in an Austrian karst system. Using a process-based flow and solute transport simulation model we estimate impacts on DIN and DOC. We show that DIN increases for several years, while DOC remains within its pre-disturbance variability. Simulated transit times indicate that impact passes through the hydrological system within some months but with a small fraction exceeding transit times of even a year.
J. Schelker, R. Sponseller, E. Ring, L. Högbom, S. Löfgren, and H. Laudon
Biogeosciences, 13, 1–12, https://doi.org/10.5194/bg-13-1-2016, https://doi.org/10.5194/bg-13-1-2016, 2016
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The scientific question that is addressed in this study is how forest disturbance affects organic and inorganic nitrogen export from a boreal landscape. The key findings are that the mobilization of inorganic nitrogen from the terrestrial environment to streams increased strongly as a response to harvesting, but the stream network removed a major fraction of this load before it reached the outlet, while organic nitrogen was not removed and transported downstream.
S. Duan and S. S. Kaushal
Biogeosciences, 12, 7331–7347, https://doi.org/10.5194/bg-12-7331-2015, https://doi.org/10.5194/bg-12-7331-2015, 2015
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There has been increased salinization of fresh water over decades during the urban evolution of watersheds. This study finds that salinization consistently increased sediment releases of labile organic carbon and total dissolved Kjeldahl nitrogen and sediment transformations of nitrate, and the salinization effects increased with percentage watershed urbanization. These findings are will be critical for forecasting changes in carbon and nutrient exports due to salt use in urban watersheds.
J. E. Vonk, S. E. Tank, W. B. Bowden, I. Laurion, W. F. Vincent, P. Alekseychik, M. Amyot, M. F. Billet, J. Canário, R. M. Cory, B. N. Deshpande, M. Helbig, M. Jammet, J. Karlsson, J. Larouche, G. MacMillan, M. Rautio, K. M. Walter Anthony, and K. P. Wickland
Biogeosciences, 12, 7129–7167, https://doi.org/10.5194/bg-12-7129-2015, https://doi.org/10.5194/bg-12-7129-2015, 2015
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In this review, we give an overview of the current state of knowledge regarding how permafrost thaw affects aquatic systems. We describe the general impacts of thaw on aquatic ecosystems, pathways of organic matter and contaminant release and degradation, resulting emissions and burial, and effects on ecosystem structure and functioning. We conclude with an overview of potential climate effects and recommendations for future research.
J. E. Vonk, S. E. Tank, P. J. Mann, R. G. M. Spencer, C. C. Treat, R. G. Striegl, B. W. Abbott, and K. P. Wickland
Biogeosciences, 12, 6915–6930, https://doi.org/10.5194/bg-12-6915-2015, https://doi.org/10.5194/bg-12-6915-2015, 2015
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We found that dissolved organic carbon (DOC) in arctic soils and aquatic systems is increasingly degradable with increasing permafrost extent. Also, DOC seems less degradable when moving down the fluvial network in continuous permafrost regions, i.e. from streams to large rivers, suggesting that highly bioavailable DOC is lost in headwater streams. We also recommend a standardized DOC incubation protocol to facilitate future comparison on processing and transport of DOC in a changing Arctic.
R. M. Cory, K. H. Harrold, B.T. Neilson, and G. W. Kling
Biogeosciences, 12, 6669–6685, https://doi.org/10.5194/bg-12-6669-2015, https://doi.org/10.5194/bg-12-6669-2015, 2015
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This study investigates how sunlight, dissolved organic matter (DOM) concentration and composition, and hydrology interact to control DOM degradation in headwater streams. In Imnavait Creek, a shallow, low-relief stream in the Arctic, DOM degradation by sunlight was limited by light under all conditions. Study results were used to synthesize controls on DOM degradation by sunlight for a river reach, expressed as a function of light attenuation and water residence times.
O. S. Pokrovsky, R. M. Manasypov, S. Loiko, L. S. Shirokova, I. A. Krickov, B. G. Pokrovsky, L. G. Kolesnichenko, S. G. Kopysov, V. A. Zemtzov, S. P. Kulizhsky, S. N. Vorobyev, and S. N. Kirpotin
Biogeosciences, 12, 6301–6320, https://doi.org/10.5194/bg-12-6301-2015, https://doi.org/10.5194/bg-12-6301-2015, 2015
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The governing parameter of DOC and major element concentrations and fluxes in western Siberia is latitude. High fluxes in the continuous permafrost zone of frozen peat bogs stem from the fact that the underlining mineral layer is not reactive, protected by the permafrost so that the major part of the active layer is located within the organic (peat) matrix and not the mineral matrix. Possible changes in export fluxes of DOC and major river water components under permafrost thaw are quantified.
D. Müller, T. Warneke, T. Rixen, M. Müller, S. Jamahari, N. Denis, A. Mujahid, and J. Notholt
Biogeosciences, 12, 5967–5979, https://doi.org/10.5194/bg-12-5967-2015, https://doi.org/10.5194/bg-12-5967-2015, 2015
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Tropical peatlands are an important source of organic carbon to rivers. However, due to the remoteness of these ecosystems, data are scarce. We present the first combined assessment of both lateral organic carbon fluxes and CO2 emissions from an undisturbed tropical peat-draining river. Compared to the organic carbon concentrations, CO2 fluxes to the atmosphere were actually relatively moderate, which we attributed to the short water residence time.
B. M. Voss, B. Peucker-Ehrenbrink, T. I. Eglinton, R. G. M. Spencer, E. Bulygina, V. Galy, C. H. Lamborg, P. M. Ganguli, D. B. Montluçon, S. Marsh, S. L. Gillies, J. Fanslau, A. Epp, and R. Luymes
Biogeosciences, 12, 5597–5618, https://doi.org/10.5194/bg-12-5597-2015, https://doi.org/10.5194/bg-12-5597-2015, 2015
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This study presents seasonal cycles of organic matter concentration and composition in the Fraser River. Dissolved organic matter patterns are linked to flushing of shallow soil layers during spring snowmelt and fall rain events. The preliminary Hg data set indicates significant changes in concentrations during the spring freshet. Organic carbon export, as both area-normalized yield and the proportion of basin primary productivity, in the Fraser River is typical of large rivers globally.
R. González-Pinzón, J. Mortensen, and D. Van Horn
Biogeosciences, 12, 5365–5369, https://doi.org/10.5194/bg-12-5365-2015, https://doi.org/10.5194/bg-12-5365-2015, 2015
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Hall et al. (2013) presented a synthesis of 969 nutrient tracer experiments and used a scaling method to test the hypothesis that nutrient demand is constant with increasing stream size. In this comment we present a reanalysis of a subset of the data used by Hall et al. (2013) and propose that their correlations between nutrient uptake lengths and specific discharge are inadvertently spurious. Therefore, the conclusions derived from such correlations are debatable.
A. J. Ulseth and R. O. Hall Jr.
Biogeosciences, 12, 4345–4359, https://doi.org/10.5194/bg-12-4345-2015, https://doi.org/10.5194/bg-12-4345-2015, 2015
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Dams impact river reaches. Upstream of dams, reservoirs transform terrestrial organic carbon and produce autochthonously derived organic carbon. In addition, tailwater reaches below dams may produce and export similar amounts of organic carbon to that stored behind dams. Our work demonstrates that not only do reservoirs need to be considered for their capacity to store and transform organic carbon but also the combined impact of their tailwater ecosystems should to be considered as well.
W. S. Zhang, D. P. Swaney, X. Y. Li, B. Hong, R. W. Howarth, and S. H. Ding
Biogeosciences, 12, 4275–4289, https://doi.org/10.5194/bg-12-4275-2015, https://doi.org/10.5194/bg-12-4275-2015, 2015
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This study provides a new approach to estimate both anthropogenic non-point source and point source nitrogen (N) inputs to the landscape, and determines their impacts on riverine ammonia-nitrogen (AN) flux, providing a foundation for further exploration of anthropogenic effects on N pollution. Our findings highlight the importance of anthropogenic N inputs from both point sources and non-point sources in heavily polluted watersheds, and provide some implications for N prediction and management.
J. R. Larouche, B. W. Abbott, W. B. Bowden, and J. B. Jones
Biogeosciences, 12, 4221–4233, https://doi.org/10.5194/bg-12-4221-2015, https://doi.org/10.5194/bg-12-4221-2015, 2015
R. Aguilera, R. Marcé, and S. Sabater
Biogeosciences, 12, 4085–4098, https://doi.org/10.5194/bg-12-4085-2015, https://doi.org/10.5194/bg-12-4085-2015, 2015
Short summary
Short summary
Nitrate and dissolved phosphate concentration time series (1980--2011) from 50 sampling stations across a large Mediterranean river basin were analyzed using dynamic factor analysis and complementary methods in order to disentangle the role of hydrology, land-use practices, and global climatic phenomena on nitrate and phosphate patterns, with the aim of understanding how the different aspects of global change affected nutrient dynamics in the basin.
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Short summary
Three cruises were conducted in the Rajang River estuary, Malaysia. The results revealed that the decomposition of terrestrial organic matter and the subsequent soil leaching were the main sources of dissolved inorganic nitrogen (DIN) in the fresh river water. Porewater exchange and ammonification enhanced DIN concentrations in the estuary water, while intensities of DIN addition varied between seasons. The riverine DIN flux could reach 101.5 ton(N) / d, supporting the coastal primary producers.
Three cruises were conducted in the Rajang River estuary, Malaysia. The results revealed that...
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