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首页> 外文期刊>Estuarine Coastal and Shelf Science >Nutrient fluctuations in the Quatipuru river: A macrotidal estuarine mangrove system in the Brazilian Amazonian basin
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Nutrient fluctuations in the Quatipuru river: A macrotidal estuarine mangrove system in the Brazilian Amazonian basin

机译：Quatipuru河中的养分波动：巴西亚马逊河盆地的巨潮河口红树林系统

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The temporal and spatial variability of dissolved inorganic nutrients (N0_3~-, NO_2~-, NH_4~+, PO_4~(3-) and DSi), total nitrogen (TN), total phosphorus (TP), nutrient ratios, suspended particulate matter (SPM) and Chlorophyll-a (Chl-a) were evaluated for the macrotidal estuarine mangrove system of the Quatipuru river (QUATIES), east Amazon coast, North Brazil. Temporal variability was assessed by fortnightly sampling at a fixed station within the middle portion of the estuary, from November 2009 to November 2010. Spatial variability was investigated from two field surveys conducted in November 2009 (dry season) and May 2010 (rainy season), along the salinity gradient of the system. The average DIN (NO_3~- + NO_2~- + NH_4~+) concentration of 9 μM in the dry season was approximately threefold greater in comparison to the rainy season. NH_4~+ was the main form of DIN in the dry season, while NO_3~- predominated in the rainy season. The NH_4~+ concentrations in the water column during the dry season are largely attributed to release by tidal wash-out of the anoxic interstitial waters of the surficial mangrove sediments. On the other hand, the higher NO_3~- levels during the wet season, suggested that both freshwater inputs and nitrification processes in the water column acted in concert. The river PO_4~(3-)" concentrations (DIP ＜ 1 μM) were low and similar throughout the year. DIN was thus responsible for the major temporal and spatial variability of the dissolved DIN:DIP (N:P) molar ratios and nitrogen corresponded, in general, to the prime limiting nutrient for the sustenance of phytoplankton biomass in the estuary. During the dry season, P-limitation was detected in the upper estuary. PO_4~(3-) adsorption to SPM was detected during the rainy season and desorption during the dry season along the salinity gradient. In general, the average Chl-a level (14.8 μg L~(-1)) was 2.5 times higher in the rainy season than in the dry season (5.9 μg L~(-1)). On average levels reached maxima at about 14 km from the estuaries' mouth, but shifts of the maximum Chl-a zone were subject to a dynamic displacement influenced by the tidal regime and seasonality of freshwater input. Our results showed that the potential phytoplankton productivity in QUATIES was subject to temporal and spatial variability between N and P limitation. The mangrove forests also played a relevant role as a nutrient source as established by the high variability of the nutrient behaviour along the estuarine gradient, consequently affecting the productivity in QUATIES.
机译：溶解的无机养分（N0_3〜-，NO_2〜-，NH_4〜+，PO_4〜（3-）和DSi），总氮（TN），总磷（TP），养分比，悬浮颗粒物的时空变化（SPM）和叶绿素a（Chl-a）被评估为巴西北部东亚马逊海岸的Quatipuru河（QUATIES）的潮汐河口红树林系统。通过从2009年11月至2010年11月在河口中部的固定站点每两周采样一次来评估时间变异性。空间变异性是根据2009年11月（旱季）和2010年5月（雨季）进行的两次野外调查进行的，沿着系统的盐度梯度。与雨季相比，旱季的平均DIN（NO_3〜-+ NO_2〜-+ NH_4〜+）浓度约为9μM。 NH_4〜+是干旱季节DIN的主要形式，而NO_3〜-在雨季占主导地位。干旱季节水柱中的NH_4〜+浓度主要归因于潮汐冲刷表层红树林沉积物的缺氧间隙水。另一方面，在雨季较高的NO_3〜-水平表明，水柱中的淡水输入和硝化过程共同起作用。河流中PO_4〜（3-）“的浓度（DIP ＜1μM）全年较低且相似。因此，DIN导致溶解的DIN：DIP（N：P）摩尔比和氮的主要时空变化通常对应于河口浮游植物生物量维持的主要限制营养素；在干燥季节，在河口上方检测到P限制；在雨季，检测到PO_4〜（3-）对SPM的吸附一般而言，雨季的平均Chl-a水平（14.8μgL〜（-1））比雨季（5.9μgL〜（-）高2.5倍。 1））。平均水位在距河口约14 km处达到最大值，但最大Chla区的移动受到潮汐和淡水输入季节的影响而发生动态位移。 QUATIES的潜在浮游植物生产力受时间和吐痰的影响N和P限制之间的最大变异性。沿河口梯度的养分行为高度可变，建立了红树林作为养分来源的重要作用，因此影响了QUATIES的生产力。

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