The role of Nuta (large amorphous particles) as a nutrient regenerator in Osaka Bay

Large amorphous particles (Nuta) observed in coastal areas after phytoplankton blooms and red tide outbreaks were collected by Nuta traps. These particles are always thickly attached to mooring ropes and/or fishing nets. From the decomposition experiments of Nuta and the sinking particles, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) regenerations were active in Nuta, but were not active in sinking particles. In Nuta, regeneration abundances during 10 days were 567 g-N/mg of initial particulate organic nitrogen (PON), and 583 -P/mg of initial particulate phosphorus (PP), respectively. Thus DIP was more regenerated from Nuta than DIN. Ten days integral regeneration abundances of DIN and DIP from Nuta were estimated to be 36% and 79% of in situ DIN and DIP standing stocks, respectively. Nuta contributes an important role of nutrient regeneration particularly DIN, in coastal water. Carbon and nitrogen stable isotope ratios of suspended particles, sinking particles and Nuta indicated that these three different type of particles were almost the same origin, and thus Nuta in the coastal water should be made from phytoplankton debris.     

Distribution and seasonal variation of phosphorus in Tokyo Bay

Phosphorus dynamics in Tokyo Bay waters were investigated along with other oceanographic variables. Seasonal variations of dissolved inorganic phosphorus (DIP) and particulate phosphorus (PP) are inversely correlated with each other, and reflect variation in biological activity. A high concentration of PP in summer surface waters is caused by high primary production. The PP settled in the deeper layer is decomposed, and orthophosphate is regenerated within the water column and in sediments. Even during summer stratification period, the regenerated orthophosphate is occasionally advected upward by wind-induced water mixing and contributes to phytoplankton growth in the upper layer. Some dissolved organic phosphorus is producedin situ from PP, but it may be rapidly decomposed in the water column. The ratios of Cchlorophylla and CN in particulate matter suggest that phytoplankton in the summer surface waters of Tokyo Bay are limited neither by nitrogen nor by phosphorus. The PN ratio in particulate matter varies substantially but it is positively correlated with the ambient concentration of DIP. Phytoplankton take up and store phosphorus within their cells when ambient DIP exceeds their demand. An abundance of total phosphorus in the summer water column can be attributed to increased discharge of river waters, although enhanced release of orthophosphate from anoxic sediments cannot be discounted.     

Horizontal distribution of particulate matter and its characterization using phosphorus as an indicator in surface coastal water,Harima-Nada,the Seto Inland Sea,Japan

To study the horizontal distribution and characterization of suspended particulate matter (SPM) in the coastal environment, the distribution and seasonal variation of particulate phosphorus (PP), divided as organic (POP) and inorganic (PIP) fractions with POC, PON, and Chl.a, in 4 seasons throughout Harima-Nada of the Seto Inland Sea, Japan, were investigated. A high concentration of PIP was observed not only in the northern coastal area, which received much freshwater discharge, but also in the channel parts. In winter, when Δσt was low, the difference between surface and bottom σt, resuspension of sinking particles or/and surface sediment which has a high PIP/PP ratio seems to have occurred, and then a high concentration of PIP in surface water was observed. In spring and summer, PIP/PP ratios (0.24) of surface waters were close to those of phytoplankton (0.1–0.2). On the other hand, PIP/PP ratios in autumn and winter, when Δσt was low, were similar to those of surface sediment in Harima-Nada (0.32–0.39). SPM in Harima-Nada showed higher PP contents than other coastal environments, and its mean value of 9.10 mg P/g was close to the phytoplankton P content of 9.75 mg P/g. This suggests that SPM in Harima-Nada was strongly affected by phytoplankton. The C/N ratio in Harima-Nada in spring was high (11), although high Chl.a and low PIP/PP were observed, possibly resulting from preferential decomposition of nitrogen in comparison with carbon. We consider that the PIP/PP ratio is a good indicator to characterize SPM and to predict its origin as well as the C/N.     

长江口跨越锋面颗粒磷季节分布变化特征及影响因素

根据2006年夏、冬季以及2007年春、秋季“海监49号”科学考察船的调查数据,分析了长江口跨越锋面区域(31.00°～31.78°N、121.04°～123.99°E)颗粒总磷(PP),颗粒无机磷(PIP),颗粒有机磷(POP)的季节变化和空间分布特征.结果表明,PIP是水体颗粒磷的主要存在形式;受长江径流输沙量的影...     

九龙江口海域中磷的化学形态分布

根据１９８７年３月至１９８８年１２月笔者在九龙江口、厦门西海域的调查研究资料，着重讨论颗粒态磷（ＰＰ）、溶解态无机磷（ＤＩＰ）、溶解态有机磷（ＤＯＰ）、总磷（ＴＰ）等各种形态磷的含量分布、季节变化，及其与叶绿素（Ｃｈｌ．ａ）、总悬浮物量（ＴＳＭ）等其他要素的关系。     

Transfer and transport of phosphorus and silica in the turbidity maximum zone of the Changjiang estuary

The concentration of suspended particulate matter (SPM), sedimentation flux, and various forms of phosphorus and silica in turbidity maximum zone (TMZ) in the Changjiang (Yangtze) estuary was studied. Based on the budget of P and Si, their mass balances in the TMZ were calculated. Results show that the variation in concentration of dissolved inorganic silicon (DISi) was mainly controlled by seawater dilution, while that of dissolved inorganic phosphorus (DIP) was considerably affected by the buffering of suspended matter and sediment. Our experiments showed that the sedimentation fluxes of SPM and particulate inorganic phosphorus (PIP), total particulate phosphorus (TPP), particulate inorganic silicon (PISi), and biological silicon (BSi) in the TMZ were 238.4 g m⁻² d⁻¹ and 28.3, 43.1, 79.0, 63.0 mg m⁻² d⁻¹, respectively. In addition, a simple method to estimate the ratio of resuspension of sediment in the TMZ was established, with which the rate in surface and bottom waters of the TMZ accounted for 55.7 and 66.1% of the total SPM, respectively, indicating that the sediment resuspension in the TMZ influenced significantly the mass balances of P and Si. Particulate adsorbed P (60.8%) and 35.5% of total particulate P discharged from the river were filtered and then deposited in the TMZ. The input flux of PIP from the river mouth was 55.9% of that of DIP, being important as biologically available P, while that of PISi was only 3.5% of DISi, showing that particulate adsorbed Si was much less important than particulate adsorbed P.     

Laboratory study of nitrogen and phosphorus remineralization during the decomposition of coastal plankton and seston

The decomposition of cultured marine phytoplankton (Skeletonema costatum) and natural estuarine seston from Narragansett Bay, RI, was studied at two temperatures (8°C and 18°C) in bottles containing sterile bay-water (30‰) and in bay-water with micro-organisms small enough to pass through a glass fibre filter (nominally < 1μ). About 50% of the particulate organic nitrogen (PON) and particulate phosphorus (PP) was immediately released to the water in dissolved organic forms from both types of organic matter. Comparison of changes in the dissolved organic nitrogen (DON) fraction in the sterile and non-sterile systems indicated that nearly all of the DON initially released was subsequently remineralized. Ammonification proceeded only in non-sterile bay-water. 20–25% of the PP was converted to dissolved inorganic-P (DIP) fraction after only 7 h in both sterile and non-sterile bay-water. Following autolytic releases of DON, DOP and DIP the initial rates of N and P remineralization were temperature dependent: Q₁₀ values for PON and PP decay during first phase of microbially mediated decomposition ranged from 1·3 to 6·4. Rates of remineralization then slowed so that about equal amounts of nutrients were remineralized (45–50% of the N and 57–60% of the P in the phytoplankton and 60–63% of the N and 36–60% of the P in the natural seston) after 30 days storage at either temperature. During 30 days of decomposition in non-sterile seawater the N/P ratios in the dissolved inorganic fractions converged on the ratios of total-N/total-P initially present in the bottles. Kinetic analysis of the decay of total organic-N (TON) and total organic-P (TOP) in the non-sterile systems and analysis of similar sets found in the literature showed that the initial stages of the decomposition of N and P from planktonic POM in vitro could be modelled as the sequential decay, at first-order rates, of two particulate fractions. The first, more labile, fraction comprised about 60% of the particulate N and P. First-order rate constants (−k, base e) for decomposition during the 1st and 2nd phases were 0·02 to 0·2 day⁻¹ and 0·003 to 0·02 day⁻¹, respectively. The decay rates are far too slow to account for the ‘rapid in situ recycling’ of nutrients needed to support phytoplankton production when other means of nutrient resupply (by advection, fixation, rainfall, etc.) are very low.     

Modelling nitrogen and phosphorus cycles and dissolved oxygen in the Zhujiang Estuary Ⅰ. Model development

wrmcrloxHuman activities related to the population growth and developrnent of industry and rnwhci-pality have led to the incrouing hadings of various POllutants into estudries during the past fewdecades. These increasing edlutant lOadings have caused declined estuallne hedth which can bemereured by a vdriety of indices. In order to obtain solutions to environrnent problerns, re-sources manageTnnt apencies are supporting a holistic approach to envirorirnental management.An effcient strategy t…     

黄河下游营养盐浓度月际变化及其对水库泄洪事件的响应

根据2017年12月—2019年12月和2018年小浪底水库泄洪期间对黄河下游营养盐的月观测和日观测,系统的分析了黄河下游溶解态营养盐浓度、组成和通量变化.结果表明,除DON(溶解有机氮)、DSi(溶解态硅)和DIP(溶解无机磷)外,其他各溶解态营养盐浓度均呈丰水期低、枯水期高的特点.在观测期间,DSi/DIN(溶解态...     

Seasonal changes in nitrogen and phosphorus transport in the lower Changjiang River before the construction of the Three Gorges Dam

Water and sediment samples were collected at Datong from June 1998 to March 1999 to examine seasonal changes in the transports of nitrogen (N) and phosphorus (P) from the Changjiang River (Yangtze River) to the East China Sea (ECS). Dissolved inorganic nitrogen (DIN; dominated by nitrate) concentration exhibited small seasonality, and DIN flux was largely controlled by water discharge. Dissolved inorganic phosphorus (DIP) concentration was inversely correlated with water discharge, and DIP was evenly delivered throughout a year. The transports of DIN and DIP from the Changjiang River were consistent with seasonal changes in nutrient distributions and P limitation in the Changjiang Estuary and the adjacent ECS. Dissolved organic and particulate N (DON and PN) and P (DOP and PP) varied parallel to water discharge, and were dominantly transported during a summer flood. The fluxes of DOP and particulate bioavailable P (PBAP) were 2.5 and 4 times that of DIP during this period, respectively. PBAP accounted for 12–16% of total particulate P (PP), and was positively correlated with the summation of adsorbed P, Al–P and Fe–P. Ca–P, the major fraction of PP, increased with increasing percent of CaCO₃. The remobilization of riverine DOP and PBAP likely accounted for the summer elevated primary production in DIP-depleted waters in the Changjiang Estuary and the adjacent ECS. The Changjiang River delivered approximately 6% of DIN (1459 × 10⁶ kg), 1% of DIP (12 × 10⁶ kg), and 2% of dissolved organic and particulate N and P to the totals of global rivers. The construction of the Three Gorges Dam might have substantially reduced the particulate nutrient loads, thereby augmenting P limitation in the Changjiang Estuary and ECS.     

以各形态磷存量研究上升流水体老化变性指标

闽南-台湾浅滩渔场上升流区研究(1987年12月至1988年11月)及台湾海峡上升流区研究(1987年7月至1988年7月)结果表明,各种形态磷含量变化对上升流生态系具有重要作用.因此,提出以涌升水体中有机、颗粒形态磷和溶解无机态磷的相对比率来表示上升流水体的老化程度,即上升流水体老化指标(AIU)为(DOP+PP)与(DIP＋DOP＋PP)之比值.研究资料表明AIU这一表达式对于上述两上升流区是合适的,海域AIU的季节性变化与其近岸上升流的消长变化规律相一致.AIU较小的区域,其水体为新涌升水,与上升流中心位置相吻合.     

Nutrients,light and phytoplankton production in the shallow,tropical coastal waters of Bandon Bay,Southern Thailand

Phytoplankton primary production and its regulation by light and nutrient availability were investigated in the shallow, tropical coastal waters of Bandon Bay, Southern Thailand. The bay was meso‐eutrophicated and highly turbid, receiving river water discharge. Water column stratification was consistently weak during both rainy and dry seasons. Dissolved inorganic nitrogen (DIN) was higher off the river mouth than in the other regions, suggesting that river water discharge was a main source of DIN. By contrast, dissolved inorganic phosphorus (DIP) showed a significant negative correlation with total water depth, implying that regeneration around the sea floor was an important source of DIP. Surface DIN and DIP showed positive correlations with surface primary production (PP) and water column primary productivity (ΣPP*), respectively. The combined correlation and model analyses indicate that total water depth had an ambivalent influence on water column primary production (ΣPP); shallower water depth induced more active regeneration of nutrients, but it also caused higher turbidity and lower light availability as a result of enhanced resuspension of sediments. Furthermore, there was a vertical constraint for phytoplankton during the rainy season: total water depth tended to be shallower than euphotic zone depth. In conclusion, light limitation and vertical constraint owing to shallow water depth appear to be more important than nutrient limitation for water column primary production in Bandon Bay.     

长江口及邻近水域氮、磷的形态特征及分布研究

根据近几年大面调查的监测资料,对长江口及邻近水域氮、磷营养盐的形态组成、时空分布及氮磷比的变动规律及其影响因素进行了分析研究。结果表明,长江口及邻近水域中硝酸盐是水体无机氮存在的主要形态,其约占总无机氮的90%,无机氮含量河口高,向东南方向愈来愈低;从该水域总磷的形态组成来看,磷营养盐主要以溶解态和颗粒态共存的形式存在,TDP略高于TPP,无机磷的平面分布与无机氮十分相似,春季无机磷含量高于夏季;N/P值变动范围大和平均值较高是该水域的主要特征,N/P值与长江径流量的大小有关系,夏季N/P值比春季高,综合分析来看,磷营养盐和光照都有可能成为该水域浮游植物生长的重要限制因子。     

黄河下游营养盐浓度、入海通量月变化及“人造洪峰”的影响

于2009年至2011年在黄河下游采集溶解及颗粒态营养盐样品,分析了黄河下游各形态营养盐的浓度变化及营养盐入海通量,结果表明各形态氮的浓度多呈丰水期低、枯水期高,溶解无机氮是溶解态氮的主要存在形式;受黄河高悬浮颗粒物含量的影响,磷以颗粒态占绝对优势,而溶解态磷以溶解无机磷为主要存在形态;生物硅的含量平均约占硅酸盐与生物硅之和的20％,硅的浓度丰水期高于枯水期.颗粒态磷与生物硅的含量与悬浮颗粒物含量呈正相关.营养盐的组成具有高氮磷比、高硅磷比、低硅氮比的特点.近年来黄河下游溶解无机氮浓度显著升高而溶解无机磷变化不大,硅酸盐的浓度有所下降.黄河下游水沙通量、营养盐入海通量有明显的季节变化,丰水期占全年总入海通量的42％～84％.调水调沙期间,各营养盐的浓度和组成均有明显变化,氮的浓度、DIN/PO4-P下降,磷与硅的浓度、SiO3-Si/DIN、SiO3-Si/PO4-P升高,颗粒态营养盐的比例明显增加.短期内大量水沙及营养盐入海通量对黄河口及渤海生态系统产生重要影响.     

夏季辽河口各形态营养盐的河口混合行为

利用2009 年7 月对辽河口水域航次的调查结果, 对该水域营养盐的形态和分布特征进行了探讨,并对其主要控制过程进行了讨论。结果表明： 辽河口水域营养盐的变化范围较大。磷主要以磷酸盐的形式存在, 其余依次是颗粒态磷PP、溶解有机磷DOP, 三者含量相差不大; 氮主要以硝酸盐的形式存在, 其余依次是溶解有机氮DON、颗粒...     

台湾海峡中北部上升流区各种形态磷的化学特性

根据１９８８年７月调查资料讨论了台湾海峡中北部海域夏季上升流区各种形态磷的分布特征。结果表明，上升流中心区（即海坛岛东侧一带水域）具有低温、高盐、低溶解氧；ＤＩｐ，ＴＤＰ，ＰＰ，ＴＰ较高；ＤＯＰ较低（０．２７）；及ＤＩＰ／ＤＯＰ比值（约为１）较高的特性。ＤＯＰ是该海域磷的主要形态（占ＴＰ的４９．２％），其含量分布及其形态转化与生物活动直接相关，是该海域生物生产力高的体现。     

Nutrient budgets and trophic state in a hypersaline coastal lagoon: Lagoa de Araruama, Brazil

Lagoa de Araruama in the state of Rio de Janeiro, Brazil, is a hypersaline lagoon with salinity varying spatially from 45 to 56. We collected water samples during monthly cruises throughout the lagoon, and along the streams feeding the system, from April 1991 to March 1992. Nutrients and other water quality parameters exhibited great spatial and temporal variations. Mass balance calculations indicate large amounts of anthropogenic nutrient inputs. The data indicate that the lagoon currently is oligotrophic but is in a state of transition to become a mesotrophic system. Molar dissolved inorganic nitrogen:dissolved inorganic phosphorus (DIN/DIP) varied between 2.2:1 and 659:1 with a volume-weighted average of 22:1. The high DIN/DIP ratio contrasts with that found in nearby lagoons, suggesting that phytoplankton primary production is limited by phosphorus in Lagoa de Araruama. The major loss of DIP is apparently driven by biological assimilation and diagenic reactions in the sediments. Calculations indicate that the lagoon is slightly net autotrophic at +0.9 mol C m⁻² yr⁻¹. This suggests that the biomass of the primary producers is restricted by phosphorus availability. Phosphorus retention in the sediment and the hypersaline state of the lagoon prevent changes in autotrophic communities and the formation of eutrophic conditions.     

海水中碱性磷酸酶活力的测定及其在磷的循环中的作用初探

建立了海水介质中浮游植物、细菌及游离态三种碱性磷酸酶活力的分光测定法。在厦门西港海域及实验生态中分别测定了这三种碱性磷酸酶的活力;同时采用~(32)P示踪法探讨了碱性磷酸酶对小球藻直接利用溶解有机磷(DOP)的影响。结果表明,浮游植物体的碱性磷酸酶活力占主导地位;当水体溶解无机磷降低到一定浓度时,浮游植物体碱性磷酸酶活力可突增,它提供了浮游植物直接利用DOP的条件。     

Analysis of the spatial and temporal distributions of ecological variables and the nutrient budget in the Beibu Gulf

Based on a hydrodynamic-ecological model, the temperature, salinity, current, phytoplankton(Chl a),zooplankton, and nutrient(dissolved inorganic nitrogen, DIN, and dissolved inorganic phosphorous, DIP)distributions in the Beibu Gulf were simulated and the nutrient budget of 2015 was quantitatively analyzed. The simulated results show that interface processes and monsoons significantly influence the ecological processes in the gulf. The concentrations of DIN, DIP, phytoplankton and zooplankton are generally higher in the eastern and northern gulf than that in the western and southern gulf. The key regions affected by ecological processes are the Qiongzhou Strait in winter and autumn and the estuaries along the Guangxi coast and the Red River in summer.In most of the studied domains, biochemical processes contribute more to the nutrient budget than do physical processes, and the DIN and DIP increase over the year. Phytoplankton plays an important role in the nutrient budget; phytoplankton photosynthetic uptake is the nutrient sink, phytoplankton dead cellular release is the largest source of DIN, and phytoplankton respiration is the largest source of DIP. The nutrient flux in the connected sections of the Beibu Gulf and open South China Sea(SCS) inflows from the east and outflows to the south. There are 113 709 t of DIN and 5 277 t of DIP imported from the open SCS to the gulf year-around.     

POC fluxes from euphotic zone estimated from 234Th deficiency in winter in the northwestern North Pacific Ocean

1IntroductionThefluxesofcarbon,nutrients,andassoci-atedelementsinvolvedinthebiogeochemicalcyclesoutoftheeuphoticzoneareimportantinthestudyofglobalCO2 change.Someworkershaveproposedthatatthesteadystatethefluxofparticulateorganiccarbonoutoftheeuphoticzoneequalsthenewproduction(EppleyandPe-terson,1979;Eppley,1989).Generallytwometh-odscanbeemployedtoobtainthefluxdata.Oneistousesedimenttrapsintheupperocean(<200m)orfloatingsedimenttraps.Thoughthesedimenttraptechnologyhasshowntobeuse-fulfortimeser…