Dissolved Inorganic Phosphate Concentration in Stream Water in Japan and Factors Controlling the Concentration

Wakamatsu, Takashi; Konohira, Eiichi; Shindo, Junko; Yoshioka, Takahito; Okamoto, K.; Itaya, Akemi; Kim, Min‐Sik

doi:10.2965/jswe.29.679

Cited by 13 publications

(17 citation statements)

References 11 publications

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“…The total P concentrations observed in our study were consistent with those reported in the previous studies (Yamamoto et al 2004(Yamamoto et al , 2008. The TP concentrations of forest-dominated streams in Japan were also within the range of trace to 0.12 mg L À1 (median of 0.007 mg L À1 ) (Wakamatsu et al 2006). Tea field soils were characterized by an extremely low pH (<4.0) and a large amount of activated reactive aluminum (Kawai and Ikegaya 1961;Goto et al 1994;Kato et al 2000), contributing the strong P retention in the tea field soils.…”

supporting

confidence: 82%

Impact of agricultural land use on N and P concentration in forest-dominated tea-cultivating watersheds

Nagumo

Yosoi

Aridomi

2012

Soil Science and Plant Nutrition

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The increase in nitrogen (N) and phosphorus (P) and the decrease in dissolved silica (DSi) in aquatic environments attributed to human activities has been the focus of many studies. The resultant increases in the N/DSi and P/DSi ratios have been associated with the disturbance and deterioration of aquatic ecosystems. We investigated the impact of land use on riverine N and P as well as their ratio to DSi in 4 mountainous forest-dominated tea-cultivating areas in Shizuoka, central Japan. More than 50% of the drainage basins investigated were under forested land, while the land under tea (Camellia sinensis) fields varied from 0 to 18% and orchard fields reached up to 30% in some cases. The total nitrogen (TN) concentration was 5 mg L À1 at maximum, the majority of which was dominated by nitrate-N. An increase in the tea field area (%) within the basin resulted in significant increase in the TN concentration (p < 0.001) and in a considerably higher impact factor of 0.1-0.2 for the tea field. Orchard fields also affected the TN concentration in corresponding areas. An increase in the tea field area significantly contributed to an increase in the TN/DSi mole-based ratio. These results indicated that tea fields are a major source of riverine N. To maintain the TN/ DSi below the critical level (TN/DSi ratio <1.0), tea fields should be cultivated only in a maximum of 30% of the watershed area, and the TN concentration should be limited to 2.5 to 4.0 mg L À1. Based on the level of precaution (TN/DSi <0.3), the TN concentration should be strictly limited to less than 1 mg L À1, which is identical to the Japanese critical standard for environmental conservation of lakes and coastal seas. On the other hand, TP concentrations were almost always below 0.1 mg L À1 and the TP/DSi ratios were considerably lower than the critical level (TP/DSi <0.07). Excess N load in the tea-cultivating watersheds might accelerate the P shortage in aquatic ecosystems. N concentration should be reduced to prevent future problems. In most of our mountainous tea-cultivating watersheds, 1 mg L À1 of TN concentration could be achieved, and generally a minimum of 2.5 to 4.0 mg L À1 should be achieved. To reduce the riverine TN concentration, the fertilizer N rate should be reduced by using modern practices to enhance N fertilizer use efficiency, such as slow-released coated urea combined with cultivar selection, without producing inferior quality tea leaves.

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supporting

confidence: 82%

Impact of agricultural land use on N and P concentration in forest-dominated tea-cultivating watersheds

Nagumo

Yosoi

Aridomi

2012

Soil Science and Plant Nutrition

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“…Yoh et al, 2001;Shibata et al, 2001). According to the large-scale survey of DIP concentration in Japanese forested streams (Wakamatsu et al, 2006), 67.9% of our sites (Table 3) could be classified as low P (< 0.13 µmol l -1 ), 11.7% could be medium P (0.13-0.32 µmol l -1 ), and 21.4% could be high P (> 0.32 µmol l -1 ).…”

Section: Characteristics Of Nutrient Concentrations and N:p Ratio Undmentioning

confidence: 90%

“…Previous studies did indicate that certain factors, including atmospheric deposition (Kunimatsu et al, 2001;Komai, 2004), vegetation (Fukushima and Matsushige, 1995), geology (Wakamatsu et al, 2006), and watershed management (Takeda, 2002), had an influence on the concentrations of P components in forested watersheds. Spatial differences in atmospheric deposition have generally contributed to the regional distribution of nitrate concentration in forested streams.…”

Section: Introductionmentioning

confidence: 99%

“…Fukushima and Matsushige (1995) found a positive relationship between the concentrations of P components and mean forest age. More recently, a nationwide survey in forested streams (Wakamatsu et al, 2006) has showed a distinct regional pattern in DIP concentrations and its association with bedrock types. Watersheds on sedimentary rocks (Paleozoic sedimentary rocks in particular) had higher DIP concentration than those on igneous or metamorphic rocks (Wakamatsu et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…More recently, a nationwide survey in forested streams (Wakamatsu et al, 2006) has showed a distinct regional pattern in DIP concentrations and its association with bedrock types. Watersheds on sedimentary rocks (Paleozoic sedimentary rocks in particular) had higher DIP concentration than those on igneous or metamorphic rocks (Wakamatsu et al, 2006). Motoshita et al (2003) found a high correlation between DTP and dissolved organic matter (DOM), which suggests that DOM has a significant influence on P leaching.…”

Section: Introductionmentioning

confidence: 99%

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Baseflow concentrations of nitrogen and phosphorus in forested headwaters in Japan

Zhang

Fukushima

Shi

et al. 2008

Science of The Total Environment

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A comprehensive investigation on all dissolved nitrogen and phosphorus components at both local and regional scales in the headwaters from forested watersheds is valuable to improve our understanding of the factors controlling water quality. Here, we investigated the baseflow concentrations of dissolved nitrogen and phosphorus components, N:P ratio, and their associations with region and vegetation type in forested headwaters in fives regions of Japan. We found that inorganic nitrogen and phosphorus were the dominant components in the 26 temperate forested streams, rather than organic forms. There were significant positive correlations between the concentrations of N and P components. Furthermore, the regional patterns of the concentrations of nitrate, dissolved inorganic P (DIP), and dissolved total N (DTN) and P (DTP) were similar. Our results suggest that the regional patterns of the concentrations of N and P components should be related to the regional atmospheric deposition of both N and P nutrients. We also found that the nitrate and DTN concentrations were higher in man-made evergreen conifer (EC) than those in the natural deciduous broadleaf (DB). In contrast, the DIP and DTP concentrations in EC were lower than those in DB. The uniformly higher N:P ratio in EC- than in DB-forested streams for each region suggest that EC-forested streams could be more affected by P-limited than DB-forested streams when N inputs from atmospheric sources increased.

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Effects of bedrock groundwater discharge on spatial variability of dissolved carbon, nitrogen, and phosphorous concentrations in stream water within a forest headwater catchment

Egusa

Kumagai

Oda

et al. 2020

Hydrological Processes

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The quantitative evaluation of the effects of bedrock groundwater discharge on spatial variability of stream dissolved organic carbon (DOC), dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP) concentrations has still been insufficient. We examined the relationships between stream DOC, DIN and DIP concentrations and bedrock groundwater contribution to stream water in forest headwater catchments in warm‐humid climate zones. We sampled stream water and bedrock springs at multiple points in September and December 2013 in a 5 km2 forest headwater catchment in Japan and sampled groundwater in soil layer in small hillslopes. We assumed that stream water consisted of four end members, groundwater in soil layer and three types of bedrock groundwater, and calculated the contributions of each end member to stream water from mineral‐derived solute concentrations. DOC, DIN and DIP concentrations in stream water were compared with the calculated bedrock groundwater contribution. The bedrock groundwater contribution had significant negative linear correlation with stream DOC concentration, no significant correlation with stream DIN concentration, and significant positive linear correlation with stream DIP concentration. These results highlighted the importance of bedrock groundwater discharge in establishing stream DOC and DIP concentrations. In addition, stream DOC and DIP concentrations were higher and lower, respectively, than those expected from end member mixing of groundwater in soil layer and bedrock springs. Spatial heterogeneity of DOC and DIP concentrations in groundwater and/or in‐stream DOC production and DIP uptake were the probable reasons for these discrepancies. Our results indicate that the relationships between spatial variability of stream DOC, DIN and DIP concentrations and bedrock groundwater contribution are useful for comparing the processes that affect stream DOC, DIN and DIP concentrations among catchments beyond the spatial heterogeneity of hydrological and biogeochemical processes within a catchment.

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Dissolved Inorganic Phosphate Concentration in Stream Water in Japan and Factors Controlling the Concentration

Cited by 13 publications

References 11 publications

Impact of agricultural land use on N and P concentration in forest-dominated tea-cultivating watersheds

Impact of agricultural land use on N and P concentration in forest-dominated tea-cultivating watersheds

Baseflow concentrations of nitrogen and phosphorus in forested headwaters in Japan

Effects of bedrock groundwater discharge on spatial variability of dissolved carbon, nitrogen, and phosphorous concentrations in stream water within a forest headwater catchment

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