Changes in Carbon and Nitrogen with Particle Size in Bottom Sediments in the Dan River, China

Quaternary International xxx (2015) 1e9

Contents lists available at ScienceDirect

Quaternary International

journal homepage: www.elsevier.com/locate/quaint

Changes in carbon and nitrogen with particle size in bottom sediments in the Dan River, China

* Xiaojun Liu a, Zhanbin Li a, b, Peng Li b, , Bingbing Zhu c, Feifei Long b, Yuting Cheng b, Tian Wang b, Kexin Lu b a State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China b State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Area at XAUT, Xi'an, Shaanxi 710048, China c College of Tourism and Environment, Shannxi Normal University, Xi'an, Shannxi 710052, China article info abstract

Article history: Understanding the composition and changes in nutrients in sediments and soil will enable a better Available online xxx description of sedimentation and environmental processes. In this study, soil from the source (Ss) of the Dan River and sediments along the river were sampled. The particle size distribution (PSD) of sediment Keywords: and soil was analyzed, together with the total nitrogen (TN), total organic carbon (TOC) and the C/N ratio. Dan river The dominant particle size of Ss was <0.05 mm, while the sediments showed no obvious dominant Sediments particles. Concentrations of TN and TOC in sediments were significantly lower than in Ss. The <0.05 mm Carbon and nitrogen fraction of sediments manifested good ability to maintain TN and TOC, as indicated by average levels of Particle size Ratio of C/N 0.59 g N/kg and 13.85 g/kg, respectively. In the downstream portion of the Dan River, the TN contents decreased, while the TOC contents remained stable throughout the river. Cluster analysis indicated that TN division became simpler as the particle size decreased, while it became more complicated for TOC. There was no significant difference in the C/N ratio of Ss among particle sizes, and the ratio was below 25:1 for all groups. Conversely, the C/N ratio of sediments increased obviously with decreasing distance to the Danjiangkou reservoir. The nitrogen levels in particles <0.05 mm were preserved relatively well so that the C/N ratio of this fraction was relatively stable. The enrichment ratio of nutrients in sediments of the upstream portion of the river also showed that a finer fraction was associated with a greater capacity for holding nutrients, especially particles <0.05 mm. Overall, comprehensive control of sediments in rivers should focus on large particle sediments. © 2015 Elsevier Ltd and INQUA. All rights reserved.

1. Introduction overlying water by absorbing pollutants from water (Yi et al., 2008). As potential contaminant sources, sediments can exert adverse Sediments in rivers have been gaining increased attention effects on water through the release of pollutants such as nutrients, worldwide owing to their importance in biogeochemistry, engi- heavy metals and other organic micro-pollutants (Junakova and neering, ﬂuvial geomorphology and landeocean interactions Balintova, 2012), leading to eutrophication of rivers and lakes (Walling and Fang, 2003; Dai et al., 2009). Due to their capacity to (Abrams and Jarrell, 1995; Xie et al., 2003; Tian and Zhou, 2007). reserve or release different materials from the water column, Wu et al. (2012) reported that the sediment of the Haihe River is a sediment acts as both a sink and source of nutrients (Aigars and potential threat to river ecology because of its phosphorus, nitrogen Carman, 2001; Southwell et al., 2010, 2011; Liang and Zhang, and organic matter (OM) contents. Additionally, an enclosure 2011). Additionally, investigations of sediments can be used to experiment conducted in a hypereutrophic subtropical Chinese evaluate the anthropogenic inﬂuence on aquatic systems lake indicated that the release of phosphorus from sediments led to (Rognerud and Fjeld, 2001). Sediments can determine the quality of eutrophication of overlying water when external loading was reduced (Xie et al., 2003). In sediment, the regeneration of dissolved inorganic nitrogen (DIN), PO4 and SiO4 plays a vital role in * nutrient equilibrium mechanisms and the global biogeochemical Corresponding author. E-mail addresses: [email protected] (X. Liu), [email protected] (P. Li). cycle (Gle et al., 2008; Llebot et al., 2010). Rivers and lakes can http://dx.doi.org/10.1016/j.quaint.2015.02.024 1040-6182/© 2015 Elsevier Ltd and INQUA. All rights reserved.

Please cite this article in press as: Liu, X., et al., Changes in carbon and nitrogen with particle size in bottom sediments in the Dan River, China, Quaternary International (2015), http://dx.doi.org/10.1016/j.quaint.2015.02.024 2 X. Liu et al. / Quaternary International xxx (2015) 1e9 recover slowly owing to the large amount of easily releasable ni- source of the middle route of the SNWTP, the Yangtze River has trogen and phosphorus, even though pollution controls are attracted increasing attention because it is adjacent to a population implemented (Wu et al., 2011). Zhang et al. (2013) considered center and exposed to unsustainable overuse (Nilsson et al., 2005). sediment to be the source of DIN in summer and winter, but to act The Dan River, a tributary of the Yangtze River, is deeply affected by as a sink in spring. Various bio-availabilities and potential to impact increasing anthropogenic influences. For satisfactory analysis of eutrophication exist when there are different bound-forms of river and lake pollution, it is important to observe sediment par- phosphorus in sediments (Hua et al., 2000). ticles and nutrients (McCauley et al., 2000; Hawa Bibi et al., 2007; Li Furthermore, sediment transport and off-site transport of nu- et al., 2007). As the transformation model of river sediments has trients from sediments markedly impacts the water quality, not yet been investigated (Topalova et al., 2009), samples were ecological environment (Sanchez et al., 2012), global geochemical collected from along the Dan River to offer data and a theoretical cycle and transport of organic carbon from land to the oceans foundation. (Ludwig et al., 1996). The type of sediment, OM, dissolved oxygen (DO), benthic organisms and hydrodynamics affect the trans- 2. Materials and methods formation of nitrogen in sediment dramatically (Liu et al., 2012; Rigaud et al., 2013). Xiang and Zhou (2011) studied the sediments 2.1. Study area of Poyang Lake and found that the spatial distribution of phos- phorous decreased from the outlet to the entrance, and this trans- The research area is located in the watershed (33120e34110 N, formation resulted from geographical factors and sediment types. 109300e111 10 E) of the Dan River in Shaanxi Province (Fig. 1). The Particle size distribution (PSD) can respond to the characteristics Dan River originates in the southern part of Shaanxi Province and of deposition and transportation (Folk and Ward, 1957; Sahu, 1964; flows into the Danjiangkou Reservoir at Wuhan, where it supplies Friedman, 1979). Additionally, the initial motion of sediment can be water to Beijing and Tianjin Municipalities in He'nan and Hubei affected by particle shapes (Wang and Dittrich, 1999). Therefore, provinces (CWRPI, 2005). The basin covers a watershed area of analyzing PSD may help us understand the origin, transportation 7769.15 km2, 24.51% (1904.24 km2) of which is farmland. The and deposition of sediment nutrients (Watson et al., 2013). To date, subtropical and temperate climate cause uneven rainfall, with many studies have been conducted to investigate nutrients and 44.8% falling from July to September. The river has an average particle size of sediments (Beck and Jones, 1996; Kaiserli et al., runoff of 82 million m3 and a sediment concentration of 4.52 kg/m3. 2002; Makarova et al., 2004; Wang et al., 2006). Multiple con- The principal vegetation in the watershed is broad-leaved forest, taminants in water are highly correlated with sediments, especially coniferous forest, mixed coniferous and broad-leaved forest, shrubs fine sediments (Garcia, 2008). In the sediment samples from Kah- and herbs (Shen et al., 2006). The crops are dominated by rice siung Harbor (Taiwan), the concentrations of polycyclic aromatic (Oryza sativa L.), maize (Zea mays L.), wheat (Triticum aestivum L.), hydrocarbons and polychlorinated biphenyl with a low density and forest by-products including shitake (Lentinula edodes)(Li et al., fraction were much higher than those of particles with a high 2008). Yellow brown soil and cinnamon soil dominate this zone, density fraction (Huang et al., 2011). In urban sediments, an inverse while azonal soil development is influenced by human economic relationship between heavy metals and particle size was found activity and natural regional conditions. (Selbig et al., 2013). However, few studies have investigated the carbon, nitrogen and ratio of carbon to nitrogen with different 2.2. Sampling particle sizes in sediments along rivers. Further information regarding these relationships could expand our understanding of A total of 44 sample points (Fig. 1, white circular points) in the sediments control and fractal theory. bottom sediment of the Dan River at five kilometer intervals and 30 Recognizing the source materials in sediment is crucial to a thorough understanding of carbon (C) cycling in water environ- ments. Extensive studies of the carbonenitrogen ratio (C/N) have been conducted to illuminate the source and fate of organic matter (Tyson, 1995; Ogawa and Ogura, 1997; Cloern et al., 2002; Goni~ et al., 2003; Usui et al., 2006; Ramaswamy et al., 2008). Low nitrogen levels and a high C/N ratio could slow the digestion rate (Rughoonundun et al., 2012). A low C/N ratio of sediments goes against nitrogen mineralization, resulting in the sediment contributing little to biogeochemical cycles (Rao et al., 2007). The optimal C/N ratio for anaerobic digestion is 25e30 (Kayhanian and Tchobanoglous, 1992). After waste water is drained into rivers, eutrophication occurs and changes the nature and C/N ratio of the system (Gao et al., 2012). The sediment enrichment ratio (SER) can be defined as the ratio of the amount of particles in sediment divided by the amount in the original soil; therefore, the ratio can express the composition of the size distribution of the eroded sediment (Defersha and Melesse, 2012). The nitrogen enrichment ratio (NER) or carbon enrichment ratio (CER) is based on similar concepts, but refers to nutrient loss. The concentration of nutrients associated with sediment increases as more fine particles are washed from upstream to downstream owing to the large surface area of clay-sized sediment (http://www. sciencedirect.com/science/article/pii/S0341816211001949FAO,1996). The South to North Water Transfer Project (SNWTP) was conducted to address water shortage problems in China. As the water Fig. 1. Study area and sample sites.

Table 1 the most nutrients, with the content of TSN and SOC in particles Percentages of particle size for Ss and sediments (%) <0.05 mm being 0.60 g N/kg and 13.81 g/kg, respectively. When Samples Particle size (mm) compared with Ss, the nutrient concentrations of sediments were fi <0.05 0.05e0.15 0.15e0.25 0.25e0.5 0.5e11e2 signi cantly lower. For different particle sizes, the TN levels in sediments were 70.62%, 74.59%, 80.17%, 79.43%, 80.01% and 52.91% Ss 51.53 18.65 8.52 12.30 7.90 1.10 lower than in Ss samples for the respective particle size fractions Sediments 16.89 16.17 13.37 23.36 21.54 8.67 Sediment 67.23 13.30 57.02 89.85 172.83 685.44 (from largest to smallest), while the TOC levels were 41.78%, 40.67%, enrichment 46.71%, 50.09%, 53.77% and 18.00% lower, respectively. Further- ratios (SER) more, TN and TOC loss of the 0.05e0.25 mm fractions was more serious than that of any other fractions. Additionally, the proportion samples of source soils (Ss) (Fig. 1, black triangular points) were of nutrient loss from the <0.05 mm fraction was smallest, illus- selected in July, 2013. The distances from every point to the Dan- trating the relatively good nutrient retention capacity. jiangkou Reservoir ranged from 31.3 km to 171.5 km, and the points The nearest reservoir of the Dan River to the sample points is the were encoded as 1e44 (Fig. 1, white numbers). The undisturbed Danjiangkou reservoir. For further analysis of the sediment samples were loaded into polyethylene bags, frozen immediately, nutrient, the changes with distance from sample sites to the Dan- and then transported to the laboratory, where they were dried and jiangkou reservoir were analyzed (Fig. 2). The TN contents showed homogenized. For further analysis of total nitrogen, total phos- decreasing fluctuation from upstream to downstream, while the phorus and total organic carbon with different particle sizes, the TOC remained stable in most parts of the river. The coefficient of samples were hand-sieved into six size fractions, <0.05 mm, variation (CV) of TOC was larger than that of TN, while the mean CV 0.05e0.15 mm, 0.15e0.25 mm, 0.25e0.5 mm, 0.5e1.0 mm and of TOC and TN was 141.65% and 65.15%. As the particle size 1.0e2.0 mm. increased, the variability of TOC increased from 126.75% to 149.65%, while that of TN decreased from 82.42% to 58.80%. In addition, the < 2.3. Methods ranges of TN contents for particles 0.05 mm along the river were highest, while those for TOC were lowest. The particle distribution was measured using a Malvern laser particle analyzer (Mastersizer 2000), while total nitrogen was 3.3. Cluster analysis of TN and TOC of sediments analyzed using the Kjeldahl digestion procedure (Foss 8400), and total organic matter was determined using a total organic carbon Cluster analysis (CA) was applied to detect multivariate simi- analyzer (Multi N/C 3100). SPSS 16.0 was used for statistical ana- larities in TN and TOC using the ward method. A dendrogram lyses, such as variance analysis (ANOVA), cluster analysis (CA).

3. Results

3.1. Particle size distribution of soil and sediments

Significant differences (p < 0.01) in the size distribution of Ss and sediment samples were observed (Table 1). Specifically, the results revealed a clear dominance of clay and silt (51.53%), fol- lowed by the 0.05e0.15 mm size fraction (18.65%). In contrast, the sediment size fractions were distributed relatively equally, with a maximum value of 23.36% (0.25e0.5 mm). These findings indicate that erosion primarily removed particles smaller than 0.05 mm while causing deposition of large particles. The sediment enrichment ratios (SER) were computed as well. Fine particles showed a tendency to decrease, while the larger particles increased. As the size increased, the enrichment became more pronounced, reaching 685.44% for particles >1 mm.

3.2. Nutrient characteristics of sediment particles

The average contents of TOC and TN of sediments and Ss were measured for the six particle sizes (Table 2). The medium size Ss particles contained more nutrients, while the content of TSN and SOC in the 0.15e0.25 mm fraction was 1.65 g N/kg and 24.98 g/kg, respectively. However, for sediments, the ﬁnest particles contained

Table 2 TN and TOC levels in Ss and sediments

Source Nutrients Particle size (mm)

>1 0.5e1 0.25e0.50 0.15e0.25 0.05e0.15 <0.05

Ss TSN (g N/kg) 1.24 1.41 1.54 1.65 1.49 1.27 SOC (g/kg) 22.36 21.25 24.54 24.98 24.66 16.84 Sediments TSN (g N/kg) 0.36 0.36 0.31 0.34 0.30 0.60 Fig. 2. Variation of TN (a) and TOC (b) in sediment along the river with different SOC (g/kg) 13.02 12.61 13.07 12.47 11.40 13.81 particle sizes.

(Fig. 3) of particles 1.0e2.0 mm was generated based on the The C/N ratio of sediment increased with distance to the Dan- rescaled distance cluster method. Clear divisions in the sampling jiangkou reservoir (Fig. 6). The average C/N ratio of each size frac- points for TN and TOC were obtained. Specifically, all points were tion was 47.50(1.0e2.0 mm), 36.72 (0.5e1.0 mm), 53.94 divided into two clusters, one characterized by lower TN and TOC (0.25e0.5 mm), 44.71 (0.15e0.25 mm), 48.20 (0.05e0.15 mm) and contents and another by higher contents. These divisions for 28.70 (<0.05 mm). Sampling points closer to the Danjiangkou sampling points were consistent with hydrological and sedimen- reservoir showed greater changes in the C/N ratio. The maximum tation processes (Reczynski et al., 2010). As the particle size CV of the C/N ratio (263.77) occurred in the 0.15e0.25 mm fraction, decreased, the points division of TN became simpler, while for TOC while the lowest CV (136.23) was observed for the <0.05 mm the division became increasingly complicated. The dendrograms of fraction. These results show that the nitrogen could be maintained particles <0.05 mm are shown in Fig. 4. relatively well in the <0.05 mm fraction when compared with the other fractions. Although the organic carbon in sediment 3.4. Carbonenitrogen ratio (C/N) decreased, the TN contents decreased more during the erosion process from land to the river (Fig. 2). Consequently, the C/N ratio of As shown in Fig. 5, the average rates of total nitrogen (TN) and sediment was obviously greater than that of Ss. total organic carbon (TOC) of source soil were all less than 25:1, indicating that the decomposition and mineralization of organic 4. Discussion matter could be high, and that the moderate degree of mineralization of Ss resulted in accumulation of nitrogen. For all soil sam- Sediment generated by erosion of land accumulates in rivers and ples, the C/N ratio ranged from 2.86 to 107.00. Based on one way wetlands (Keddy, 2000). Accordingly, sequestering nutrients in ANOVA, the C/N ratio did not differ between groups (different sediment can improve the water quality of rivers (Wang et al., particle sizes) (P > 0.05). These findings illustrate that the particle 2004). The particle size characteristics of sediment are also size of soil had little effect on the C/N ratio. The moderate C/N ratio important to model predictions for related hydrological and of the source in the study area likely results in increased microflora ecological processes (Saye and Pye et al., 2006). The distributions of and better soil fertility. TOC and TN in particle-size fractions are of great significance for

Fig. 3. Cluster analysis of TN (a) and TOC (b) contents of sediments in the 1.0e2.0 mm fraction.

Fig. 4. Cluster analysis of TN (a) and TOC (b) contents for particles <0.05 mm. analysis of how sediments inﬂuence water quality in the river, which corresponds with the results of a study conducted in Taihang including nutrient accumulation and release (Reddy et al., 1993). Mountain (Qin et al., 2010). Although the CV of TOC contents in sediment tended to increase To evaluate the integral level, the TN and SOC contents were with increasing particle size, the greatest variation was observed calculated based on the PSD and the corresponding nutrient for the 0.05e0.15 mm fraction. This may indicate that microor- ganisms have intense activities that lead to more frequent release and accumulation of organic carbon relative to other particle sizes,

Fig. 5. Carbonenitrogen ratio of source soil of different particle sizes (mm). Fig. 6. C/N ratio along the Dan River for different particle sizes.

the TN content was higher for all sizes, supporting the theory that fine particles better retain nutrients. The changes in overall contents along the river are shown in Fig. 7. Comparison of the changes in particles revealed that the amplitude of TOC was reduced downstream. Consequently, the influence of the external factors was more obvious on individual sediment particle size fractions than on sediment as a whole. Large changes in the TOC along the Dan River were only observed in the downstream portions (samples 29e44). This sec- tion of the river was far from the expressway, while the upstream area was located close to the highway. Accordingly, the residential land was widely distributed in the downstream area and frequent anthropogenic activities exerted a great effect on water quality. Although the highway could play a role in water pollution (Stagge et al., 2012), the random dispersion of anthropogenic activities induced large variations in nutrient concentrations (Sylvan et al., Fig. 7. The change of overall contents along the Dan River. 2007; Diaz and Rosenberg, 2008; Selman and Greenhalgh, 2009). Fertilizer use, as well as industrial and residential sewage on farm land could lead to nutrient loss (Huang et al., 2014), resulting in concentrations. The average TN and SOC content of bottom sedi- large changes in the TOC contents in sediment. ment in Dan River was 9.73 g/kg and 0.37 g/kg, respectively. The Cluster analysis (CA) was carried out on group sediments of the concentration of SOC and CV value (48.11%, 55.36%, respectively) of sample facies and confirms the correlation between TOC and TN the nutrients was lower than that in individual size fraction (See (http://www.sciencedirect.com/science/article/pii/ Table 2). Conversely, with the exception of the 0.05 mm fraction, S0883292712001011Einax et al., 1998). The main purpose of CA is to

Fig. 8. Cluster analysis of TN (a) and TOC (b) contents in the <0.05 mm fraction considering altitude factor.

To compare the nitrogen and carbon contents between the Ss and sediments, sample points in the upstream portion of the Dan River (samples 1e16) were used to calculate the enrichment ratios (ER, %) and the ratio of nutrients (nitrogen and carbon) in sediment to those in Ss (Fig. 9). As the distance from the Danjiangkou reservoir decreased, the nitrogen enrichment ratio (NER) declined. At the head of the river, sediments nutrient loss was not very serious; however, it became greater as the distance from Dan- jiangkou reservoir decreased due to the release from sediments, which led to even less than 10% of nitrogen being left in some particles. Analysis of the carbon enrichment ratio (CER) showed a similar trend. The relatively higher release of nutrients may be correlated with the better water quality, which contained a lower concentration of nutrients. As the particle size increased, the CER and NER both increased, suggesting that the ﬁner particles had a greater capacity to hold nutrients. Overall, TN reduction was more severe than TOC and therefore requires greater attention when managing water pollution. Even though the soil loss for particles <0.05 mm was highest (69.73%), the nutrient loss and C/N ratio was lowest. When compared to other sizes, the clay fraction tended to erode and the nutrients (N and C) became more likely to adsorb onto this fraction (Zhang et al., 2011). Several investigators (Kiem and Kogel-Knabner,€ 2003; Wright and Hons, 2005; Yang et al., 2007) also observed higher C/N ratios in micro-aggregates, while Tripathi et al. (2014) obtained the opposite results. Due to the wealth of the clay fraction with more micro-aggregates, the C/N ratio decreased as the particle size decreased (Kandeler et al., 1999).

5. Conclusions

Bottom sediments and source soil (Ss) collected in July of 2013 Fig. 9. The nitrogen and carbon ER in the upstream portion of the river (NER: nitrogen from the Dan River were analyzed for particle size distribution, C ER; CER: carbon ER). and N. The following conclusions can be drawn from the results of this study: classify the objects into categories based on similarities (Ramaswamy et al., 2014); however, the results obtained are only 1. The PSD of sediments was more even than that of Ss. As the qualitative (Gielar et al., 2012). As particle size decreased, the particle size increased, the TSN and SOC contents increased, cluster of TN (Figs. 3 and 4) in sediments along the Dan River then decreased. The TN and TOC contents of sediments were tended to become simpler, indicating that the concentration of TN lower than that of Ss, but particles <0.05 mm were capable of was highest in several specific intervals (0.1e0.5 g/kg; 0.55e1.0 g/ maintaining nutrient levels. From the up to downstream portion kg). Conversely, the division of TOC contents decreased as the of the Dan River, the TN contents decreased, while the TOC particle size of sediments declined. These findings inferred that contents remained stable. carbon is more active between sediments and the aquatic envi- 2. Cluster analysis indicated that TN division became simpler as ronment, which corresponds to the release, absorption and trans- the particle size decreased, while it became more complicated formation process. All identified groups reflected the function and for TOC. These findings correspond to the hydrological and location within the geomorphic setting (Maghsoudi et al., 2014). sedimentation processes. Soil nutrients are influenced by factors such as soil character- 3. The C/N ratios of Ss were all below 25:1, and the differences istics, vegetation type and topography (Stewart et al., 2014), and among the six particle sizes were not significant (P > 0.05). As that the nutrients released by rainfall or wind transport (Caon et al., the distance to Danjiangkou reservoir decreased, the C/N ratio of 2014) have direct or indirect effects on sediment. To determine the sediments increased obviously, but the nitrogen in particles impact of terrain factors on TOC and TN, cluster analysis was <0.05 mm was preserved relatively well so that the C/N ratio executed after injecting altitude data. In contrast to the original remained more stable than for other sizes. results, including altitude data resulted in the clusters of TOC and TN being similar among different particle size fractions (Fig. 8). Overall, fine sediments, especially those smaller than 0.05 mm, Therefore, dendrograms generated using particles <0.05 mm were could be retained within the river ecosystem. Accordingly, larger listed as an example. Furthermore, the samples within a certain particles should receive greater attention because the fine sedi- range of altitude were classified into one group. For example, the ments appear to be more effective at preserving nutrition. altitude of samples 27e32 ranged from 322 m to 398 m, which was relatively small; accordingly, they were placed into the same cluster Acknowledgments as indicated in the figure. The prevailing fluid flow driven by different terrain has the potential to develop a diverse composition The research was supported by the National Natural Science of of underlying sediment (Turnewitsch et al., 2013), indicating that China (No. 41330858, No. 41271290, No. 41401316 and No. the TOC and TN contents in sediment were significantly influenced 41471226), the Special Fund of Scientific Research in the Public by topographic factors. Interest of Ministry of Water Resources (No. 201201084) and the

National Basic Research Program of China (No. 2011CB403302). Li, Siyue, Gu, Sheng, Liu, Wenzhi, Han, Hongyin, Zhang, Quanfa, 2008. Water quality We thank the reviewers for their useful comments and in relation to the land use and land cover in the Upper Han River basin, China. Catena 75, 216e222. suggestions. Liang, W., Zhang, S., 2011. Analysis of characteristics of contaminated surface sediments in Wuliangsuhai Lake. Water Saving Irrigation 4, 35e39. Liu, S.M., Li, L.W., Zhang, G.L., Liu, Z., Yu, Z., Ren, J.L., 2012. Impacts of human activities on nutrient transports in the Huanghe (Yellow River) estuary. Journal of References Hydrology 430e431, 103e110. Llebot, C., Spitz, Y.H., Sole, J., Estrada, M., 2010. The role of inorganic nutrients and Abrams, M.M., Jarrell, W.M., 1995. Soil-phosphorus as a potential non-point source dissolved organic phosphorus in the phytoplankton dynamics of a Mediterra- for elevated stream phosphorus levels. Journal of Environmental Quality 24 (1), nean bay A modeling study. Journal of Marine Systems 83, 192e209. 132e138. Ludwig, W., Probst, J.L., Kempe, S., 1996. Predicting the oceanic input of organic Aigars, J., Carman, R., 2001. Seasonal and spatial variations of carbon and nitrogen carbon by continental erosion. Global Biogeochemical Cycles 10, 23e41. distribution in the surface sediments of the Gulf of Riga, Baltic Sea. Chemo- Makarova, M.I., Haumaier, L., Zech, W., Malyshev, T.I., 2004. Organic phosphorus sphere 43 (3), 313e320. compounds in particle-size fractions of mountain soils in the northwestern Beck, Angus J., Jones, Kevin C., 1996. The effects of particle size, organic matter Caucasus. Geoderma 118, 101e114. content, crop residues and dissolved organic matter on the sorption kinetics of McCauley, D.J., DeGraeve, G.M., Linton, T.K., 2000. Sediment quality guidelines and atrazine and isoproturon by clay soil. Chemosphere 32, 2345e2358. assessment: overview and research needs. Environmental Science & Policy 3, Caon, Lucrezia, Vallejo, V. Ramon, Ritsema, Conen J., et al., 2014. Effects of wildfire S133eS144. on soil nutrients in Mediterranean ecosystems. Earth-Science Reviews 139, Maghsoudi, Mehran, Simpson, Ian A., Kourampas, Nikos, et al., 2014. Archaeological 47e58. sediments from settlement mounds of the Sagzabad Cluster, central Iran: hu- Cloern, J.E., Canuel, E.A., Harris, D., 2002. Stable carbon and nitrogen isotope man-induced deposition on an arid alluvial plain. Quaternary International 324, composition of aquatic and terrestrial plants of the San Francisco Bay estuarine 67e83. system. Limnology and Oceanography 47, 713e729. Nilsson, C., Reidy, C.A., Dynesius, M., Revenga, C., 2005. Fragmentation and flow CWRPI (Changjiang Water Resources Protection Institute), 2005. Report on the regulation of the world's large river systems. Science 308, 405e408. Environmental Impacts of Middle Route of South-to-North Water Transfer Ogawa, N., Ogura, N., 1997. Dynamics of particulate organic matter in the Tamagawa Project. Wuhan, China (in Chinese). Estuary and Inner Tokyo Bay. Estuarine and Coastal Shelf Science 44, 26e273. Dai, S.B., Yang, S.L., Li, M., 2009. Sharp decrease in suspended sediment supply from Qin, Shuping, Hu, Chunsheng, He, Xinhua, Dong, Wenxu, Cui, Junfang, Wang, Ying, China's rivers to the sea: anthropogenic and natural causes. Hydrological Sci- 2010. Soil organic carbon, nutrients and relevant enzyme activities in particle- ence Journal 54, 135e146. size fractions under conservational versus traditional agricultural management. Defersha, Mengistu B., Melesse, Assefa M., 2012. Effect of rainfall intensity, slope Applied Soil Ecology 45, 152e159. and antecedent moisture content on sediment concentration and sediment Ramaswamy, V., Gaye, B., Shirodka, P.V., Rao, P.S., Chivas, A.R., Wheeler, D., Thwin, S., enrichment ratio. Catena 90, 47e52. 2008. Distribution and sources of organic carbon, nitrogen and their isotopic Diaz, R.J., Rosenberg, R., 2008. Spreading dead zones and consequences for marine signatures in sediments from the Ayeyarwady (Irrawaddy) continental shelf, ecosystems. Science 321, 926e929. northern Andaman Sea. Marine Chemistry 111, 137e150. Einax, J.W., Truckenbrodt, D., Kampe, O., 1998. River pollution data interpreted by Ramaswamy, V., Paramasivam, K., Suresh, G., et al., 2014. Function of minerals in the means of chemometric methods. Microchemical Journal 58, 315e324. natural radioactivity level of Vaigai River sediments, Tamilnadu, India e spec- FAO, 1996. Irrigation and Drainage Papers. Version 55. 0254e5284. troscopical approach. Spectrochimica Acta Part A: Molecular and Biomolecular Folk, R.L., Ward, W., 1957. Brazos River bar: a study in the significance of grain size Spectroscopy 117, 340e350. parameters. Journal of Sedimentary Petrology 27, 3e26. Rao, Alexandra M.F., McCarthy, Mark J., Gardner, Wayne S., Jahnke, Richard A., 2007. Friedman, G.M., 1979. Differences in size distribution of populations of particles Respiration and denitrification in permeable continental shelf deposits on the among sands of various origins. Sedimentology 26, 859e862. South Atlantic Bight: Rates of carbon and nitrogen cycling from sediment col- Gao, Xuelu, Yang, Yuwei, Wang, Chuanyuan, 2012. Geochemistry of organic carbon umn experiments. Continental Shelf Research 27, 1801e1819. and nitrogen in surface sediments of coastal Bohai Bay inferred from their ratios Reczynski, Witold, Jakubowska, Malgorzata, Golas, Janusz, et al., 2010. Chemistry of and stable isotopic signatures. Marine Pollution Bulletin 64, 1148e1155. sediments from the Dobczyce Reservoir, Poland, and the environmental im- Garcia, M.H., 2008. Sedimentation Engineering: Processes, Measurements, plications. International Journal of Sediment Research 25, 28e38. Modeling, and Practice. ASCE manuals and reports on engineering practice, Reddy, K.R., Delaune, R.D., DeBusk, W.F., Koch, M.S., 1993. Long-term nutrient American society of civil engineers (ASCE) 110. accumulation rates in the Everglades. Soil Science Society of America Journal 57, Gielar, Agnieszka, Helios-Rybicka, Edeltrauda, Moller,€ Stefan, Einax, Jürgen W., 2012. 1147e1155. Multivariate analysis of sediment data from the upper and middle Odra River Rigaud, S., Radakovitch, O., Couture, R.M., Deflandre, B., Cossa, D., Garnier, C., (Poland). Applied Geochemistry 27, 1540e1545. Garnier, J.M., 2013. Mobility and fluxes of trace elements and nutrients at the Gle, C., Del Amo, Y., Sautour, B., Laborde, P., Chardy, P., 2008. Variability of nutrients sediment-water interface of a lagoon under contrasting water column and phytoplankton primary production in a shallow macrotidal coastal oxygenation conditions. Applied Geochemistry 31, 35e51. ecosystem (Arcachon Bay, France). Estuarine, Coastal and Shelf Science 76, Rognerud, S., Fjeld, E., 2001. Trace element contamination of Norwegian Lake 642e656. sediments. Ambio 30, 11e19. Goni,~ M.A., Teixeira, M.J., Perkey, D.W., 2003. Sources and distribution of organic Rughoonundun, Hema, Mohee, Romeela, Holtzapple, Mark T., 2012. Influence of matter in a river-dominated estuary (Winyah Bay, SC, USA). Estuar. Coast. Shelf carbon-to-nitrogen ratio on the mixed-acid fermentation of wastewater sludge Sci. 57, 1023e1048. and pretreated bagasse. Bioresource Technology 112, 91e97. Hawa Bibi, M., Ahmed, F., Ishiga, H., 2007. Assessment of metal concentrations in Sahu, B.K., 1964. Depositional mechanisms from the size analysis of clastic sedi- lake sediments of southwest Japan based on sediment quality guidelines. ments. Journal of Sedimentary Petrology 34, 73e83. Environmental Geology 52, 625e639. Sanchez, P.B., Oliver, D.P., Castillo, H.C., Kookana, R.S., 2012. Nutrient and sediment Hua, Z.Z., Zhu, X.Q., Wang, X.R., 2000. Study on bioavailability of Selenastrum concentrations in the PagsanjaneLumban catchment of Laguna de Bay, capricornutum influenced by released phosphorus. Acta Scientiae Circum- Philippines. Agricultural Water Management 106, 17e26. stantiae (20), 100e105. Saye, Samantha E., Pye, Kenneth, 2006. Variations in chemical composition and Huang, Yunjie, Lee, Chonlin, Fang, Mengder, 2011. Distribution and source differ- particle size of dune sediments along the west coast of Jutland, Denmark. entiation of PAHs and PCBs among size and density fractions in contaminated Sedimentary Geology 183, 217e242. harbor sediment particles and their implications in toxicological assessment. Selbig, William R., Bannerman, Roger, Corsi, Steven R., 2013. From streets to Marine Pollution Bulletin 62, 432e439. streams: Assessing the toxicity potential of urban sediment by particle size. Huang, Changchun, Wang, Xiaolei, Yang, Hao, Li, Yunmei, Wang, Yanhua, Chen, Xia, Science of the Total Environment 444, 381e391. Xu, Liangjiang, 2014. Satellite data regarding the eutrophication response to Selman, M., Greenhalgh, S., 2009. Eutrophication: Sources and Drivers of Nutrient human activities in the plateau lake Dianchi in China from 1974 to 2009. Sci- Pollution. World Resources Institute, Washington, DC. ence of The Total Environment 485e486, 1e11. Shen, Zehao, Zhang, Quanfa, Yue, Chao, Zhao, Jun, Hu, Zhiwei, Lv, Nan, Junakova, A.N., Balintova, M., 2012. Assessment of nutrient concentration in Tang, Yuanuan, 2006. The spatial pattern of land use/land cover in the water reservoir bottom sediments. Procedia Engineering 42, 165e170. supplying area of the middle route of the South to North water diversion Kaiserli, A., Voutsa, D., Samara, C., 2002. Phosphorus fractionation in lake Project. Acta Geographica Sinica 61, 633e644. sediments-Lakes Volvi and Koronia, N. Greece. Chemosphere 46, 1147e1155. Southwell, M.W., Kieber, R.J., Mead, R.N., Avery, G.B., Skrabal, S.A., 2010. Effects of Kandeler, E., Stemmer, M., Klimanek, E.-M., 1999. Response of soil microbial sunlight on the production of dissolved organic and inorganic nutrients from biomass, urease and xylanase within particle size fractions to long-term soil resuspended sediments. Biogeochemistry 98, 115e126. management. Soil Biology and Biochemistry 31, 261e273. Southwell, M.W., Mead, R.N., Luquire, C.M., Barbera, A., Avery, G.B., Kieber, R.J., Keddy, P.A., 2000. Wetland Ecology Principles and Conservation. Cambridge Uni- Skrabal, S.A., 2011. Influence of organic matter source and diagenetic state on versity Press, Cambridge. photochemical release of dissolved organic matter and nutrients from resus- Kiem, R., Kogel-Knabner,€ I., 2003. Contribution of lignin and polysaccharides to the pendable estuarine sediments. Marine Chemistry 126, 114e119. refractory carbon pool in C-depleted arable soils. Soil Biol. Biochem 35, 101e118. Stagge, James H., Davis, Allen P., Jamil, Eliea, et al., 2012. Kim Performance of grass Li, W., Liu, J., Wan, Z., 2007. Regulation of flow and sediment load in the Yellow swales for improving water quality from highway runoff. Water Research 46, River. International Journal of Sediment Research 22 (2), 103e113. 6731e6742.

Stewart, Katherine J., Grogan, Paul, Coxson, Darwyn, S., et al., 2014. Topography as a Watson, Elizabeth Burke, Pasternack, Gregory B., Gray, Andrew B., et al., 2013. key factor driving atmospheric nitrogen exchanges in arctic terrestrial ecosys- Particle size characterization of historic sediment deposition from a closed tems. Soil Biology and Biochemistry 70, 96e112. estuarine lagoon, Central California. Estuarine. Coastal and Shelf Science 126, Sylvan, J.B., Quigg, A., Tozzi, S., Ammerman, J.W., 2007. Eutrophication-induced 23e33. phosphorus limitation in the Mississippi River plume: evidence from fast Wright, A.L., Hons, F.M., 2005. Soil carbon and nitrogen storage in aggregates from repetition rate fluorometry. Limnology and Oceanography 52, 2679e2685. different tillage and crop regimes. Soil Sci. Soc. Am. J 69, 141e147. Tian, J.R., Zhou, P.J., 2007. Phosphorus fractions of floodplain sediments and phos- Wu, Min, Huang, Suiliang, Wen, Wei, Sun, Xueming, Tang, Xianqiang, Miklas, Scholz, phorus exchange on the sediment-waterinterface in the lower reaches of the 2011. Nutrient distributions associated with snow and sediment-laden layers in Han River in China. Ecological Engineering 30 (2), 264e270. sea ice of the southern Sea of Okhotsk. Journal of Environmental Sciences 23, Topalova, Yana, Todorova, Yovana, Panova, Antoaneta, Schneider, Irina, 2009. 1086e1094. Modelling of the relationship moisture content to nutrient transformation rate Wu, Min, Sun, Xueming, Huang, Suiliang, Tang, Xianqiang, SCHOLZ, Miklas, 2012. in river sediments. Ecological Modelling 220, 3325e3330. Laboratory analyses of nutrient release processes from Haihe River sediment. Tripathi, Rahul, Nayak, A.K., Bhattacharyya, Pratap, et al., 2014. Soil aggregation and International Journal of Sediment Research 27, 61e72. distribution of carbon and nitrogen in different fractions after 41 years long-term Xiang, Sulin, Zhou, Wenbin, 2011. Phosphorus forms and distribution in the sedi- fertilizer experiment in tropical riceerice system. Geoderma 213, 280e286. ments of Poyang Lake, China. International Journal of Sediment Research 26, Turnewitsch, Robert, Falahat, Saeed, Nycander, Jonas, et al., 2013. Deep-sea fluid and 230e238. sediment dynamics-Influence of hill- to seamount-scale seafloor topography. Xie, L.Q., Xie, P., Tang, H.J., 2003. Enhancement of dissolved phosphorus release Earth-Science Reviews 127, 203e241. from sediment to lake water by microcystis bloomsean enclosure experiment Tyson, R.V., 1995. Sedimentary Organic Matter. Chapman and Hall, London. in a hyper-eutrophic, subtropical Chinese lake. Environmental Pollution 122 (3), Usui, Toshihiro, Nagao, Seiya, Yamamoto, Masanobu, et al., 2006. Distribution and 391e399. sources of organic matter in surficial sediments on the shelf and slope off Yang, Zhihui, Singh, Bal Ram, Hansen, Sissel, 2007. Aggregate associated carbon, Tokachi, western North Pacific, inferred from C and N stable isotopes and C / N nitrogen and sulfur and their ratios in long-term fertilized soils. Soil Tillage Res. ratios. Marine Chemistry 98, 241e259. 95, 161e171. Walling, D.E., Fang, D., 2003. Recent trends in the suspended sediment loads of the Yi, Y.J., Wang, Z.Y., Zhang, K., Yu, G.A., Duan, X.H., 2008. Sediment pollution and its world rivers. Global and Planetary Change 39, 111e126. effect on fish through food chain in the Yangtze river. International Journal of Wang, Z.Y., Dittrich, A., 1999. Effect of particle's shape on incipient motion of Sediment Research 23 (4), 338e347. sediment. International Journal of Sediment Research 14 (2), 179e186. Zhang, Guanhua, Liu, Guobin, Wang, Guoliang, Wang, Yuxia, 2011. Effects of vege- Wang, Guoping, Liu, Jingshuang, Tang, Jie, 2004. The long-term nutrient accumu- tation cover and rainfall intensity on sediment-bound nutrient loss, size lation with respect to anthropogenic impacts in the sediments from two composition and volume fractal dimension of sediment particles. Pedosphere freshwater marshes (Xianghai Wetlands, Northeast China). Water Research 38, 21 (5), 676e684. 4462e4474. Zhang, Ling, Wang, Lu, Yin, Kedong, Lü, Ying, Zhang, Derong, Yang, Yongqiang, Wang, Shengrui, Jin, Xiangcan, Bu, Qingyun, Zhou, Xiaoning, Wu, Fengchang, 2006. Huang, Xiaoping, 2013. Pore water nutrient characteristics and the fluxes across Effects of particle size, organic matter and ionic strength on the phosphate the sediment in the Pearl River estuary and adjacent waters, China. Estuarine, sorption in different trophic lake sediments. Journal of Hazardous Materials Coastal and Shelf Science 1e11. A128, 95e105.