珠江口表层沉积物中氮、磷的形态分布特征及污染评价

珠江口是生态敏感的典型河口区,也是富营养化和赤潮多发区。为了搞清楚该区域沉积物中营养物质的含量及平面分布特征,进一步研究营养盐在沉积物-水体间的循环机制,同时也为珠江口污染防治和生态环境保护提供科学依据,对珠江口16个站位的表层沉积物中氮、磷的形态、含量及分布特征进行了研究。其中总氮用凯氏定氮法测定,无机氮提取后直接测定各形态含量,各种形态的磷采用化学分步提取法进行。提取液中硝酸盐氮用锌-镉还原法,亚硝酸盐氮用重氮-偶氮比色法,氨氮用靛酚蓝法,无机磷酸盐用磷钼蓝法测定。沉积物中TOC的测定用重铬酸钾氧化-还原滴定法。在测定结果的基础上采用单项指标标准指数法对沉积物中氮和磷的污染程度进行了评价。研究结果表明:沉积物中总氮的含量较高,平均值高达1649mg/kg;有机氮所占的比例很高,平均达83.17%,平均含量为1374mg/kg;氨氮是无机氮的主要形式,平均占无机氮的98%,平均含量为209.64mg/kg;硝酸盐氮和亚硝酸盐氮在沉积物无机氮中比例很低,平均值为54.87mg/kg。表层沉积物中总磷的含量平均值为455.94mg/kg;有机磷占总磷含量的39.41%,平均含量为179.69mg/kg;铁结合磷和铝结合磷平均含量为94.97mg/kg。在平面分布上,各站间不同形态氮、磷的含量差异与陆源输入、沉积物粒径及水动力条件等因素有关。单项指标标准指数法对沉积物中氮和磷的污染评价结果表明:珠江口沉积物中总磷含量较低,标准指数都小于1;而总氮的含量较高,其标准指数变化范围为1.96—3.86,说明珠江口沉积物环境质量受氮的污染相对严重。     

Laboratory Simulation on Phosphorus Releasing near the Water／Sediment Interface in the East China Sea off the Changjiang Estuary

Surface sediment samples taken from the East China Sea off the Changjiang estuary are used as raw materials for phosphorus releasing experiment. It is found that after being thoroughly mixed with seawater for about 10 minutes, phosphorus released from the sediments reaches its maximum value. Adsorption kinetics can be fitted with both Elovich equation and two-constant rate equation. The releasing amount is closely related to the composition of the sediments. Phosphorus release from silty and muddy sediment is higher than from that dominated by sandy composition. For the desorption reaction, iron-phosphorus(Fe-P) is the most active one, with a releasing ratio higher than other phosphorus forms,followed by absorbed-phosphorus (Ad-P) and organic bound phosphorus (OP). All of them can be referred to as bio-available phosphorus. The results demonstrate that phosphorus in sediments can be released into seawater under suitable hydrodynamic conditions, and have a great impact on the nutrition state and primary productivity of marine biosphere.     

珠江口沉积物有机质特征、来源及其对碳存储的意义

河口沉积物作为承接陆海过程的重要载体, 是有机质赋存的主要形式之一。本文研究了珠江口沉积物总有机碳、总氮含量和沉积物可溶性有机物三维荧光特征, 以及其在口内区、混合区和口外区空间差异和影响因素, 并结合碳稳定同位素(δ¹³C)估算了珠江口各区域沉积物中不同来源有机质的贡献。结果显示: (1)沉积物总有机碳和总氮含量空间变化相似, 口内区和混合区域沉积有机质含量显著高于口外区; 主成分分析发现, 口内区沉积有机质含量主要受径流输入的影响, 口外区主要受Fe³⁺的影响; (2)MixSIAR稳定同位素混合模型结果显示, 口内区和混合区沉积有机质以陆源为主, 口外区则以海源为主; (3)珠江口沉积物新生有机质较多, 可快速被利用, 总体上不利于有机碳存储; 而陆源输入导致口内区和混合区沉积有机质腐殖化程度较高, 有机碳可存储性相对较高, 口外受海源有机质和铁氧化物—有机质复合体的影响, 有机碳可存储性相对较低。本研究可为深入认知河口区沉积有机质的生物地球化学过程及有机碳存储提供参考。     

长江口悬沙动力特征与输运模式

本项研究用ADCP在长江河口进行高频、高分辨率三维流速和声学浊度的定点观测,通过对定点站位潮周期内的悬沙浓度、流速和盐度的分析,计算悬沙输运率;悬沙输运机制分析表明平流作用、斯托克斯漂移效应在悬沙输运中占据主导地位.此外,从河口内向河口外,潮周期内的水动力特征与悬沙净输运具有明显的地域性差异,主要表现在悬沙输送的贡献因子、盐度的垂向混合和分布特征、垂向流速等方面.在拦门沙下游和口外地区,悬沙均向西、北方向输送,而拦门沙上游则向东、南方向输送.这种悬沙输运格局,对于长江口拦门沙及附近最大浑浊带的形成有着重要的作用.     

九龙江口水体中各形态磷的行为

１９９御３月至１９９６年２月，逐月从九龙江口的淡水端到入海端的全段河口区采取表层水样。测定并计算水体溶解态和颗粒态的磷：ＤＩＰ，ＤＯＰ，ＤＴＰ，ＰＩＰ，ＰＯＰ，ＰＴＰ和ＴＰ。结果表明，河流为九龙江口带来大量的磷。其主要以无机态的ＰＩＰ，ＤＩＰ形式存在。     

藻类生长对沉积物上磷迁移转化的影响

通过模拟中肋骨条藻(Skeletonema costatum)和沉积物共存体系,探究了富营养化条件下,藻类与沉积物对无机磷的吸收/吸附作用的相互影响。采用自制的金汞伏安微电极测定了藻与沉积物共存体系中溶解氧(DO)的含量变化,分析了体系中溶解氧含量变化与磷消耗速率以及沉积物中磷形态分布变化之间的关系。结果表明,在本课题研究范围内,共存的藻类与沉积物互相影响彼此对磷的消耗过程,1.0×10^4、5.0×10^4和1.0×10^5 cells/mL三种初始藻密度的中肋骨条藻(Skeletonema costatum)48 h后对磷的吸收百分比分别达54.7%、73.4%、93.8%,添加沉积物后分别降至21.3%、34.1%和51.9%;沉积物对培养基介质中的无机磷的吸附百分比为42.5%,加入三种不同藻密度的藻体后分别降至9.1%、2.8%及0.3%。高密度藻与沉积物共存体系的耗磷速率与体系DO含量呈显著负相关(p<0.05)。体系中DO浓度降低会促进沉积物中Fe-P向水体中释放,从而导致沉积物中铁结合态磷(Fe-P)含量的降低。可交换态磷(Ex-P)、有机磷(OP)和Fe-P是藻类存在时沉积物向水体中较易释放的形态。     

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。     

不同时间尺度下长江口海域表层悬浮体浓度变化

长江入海泥沙是中国东部陆架海沉积物的主要来源之一。本文基于MODIS-Aqua卫星的遥感资料并结合实测悬浮体浓度,建立了基于颗粒物后向散射系数的悬浮体浓度的反演方法,获取了2002—2017年长江口海域的表层悬浮体浓度分布,并分析其在潮周期、季节内以及年际等不同时间尺度下的变化特征。结果表明,在潮周期内,长江口122.3°E以西海域表层悬浮体浓度大潮高于小潮,落潮大于涨潮,高潮大于低潮;在季节尺度内.6—8月表层悬浮体浓度逐渐增加。而122.3°E以东海域,则出现相反的情况;长江口122.3°E以西海域的夏季平均表层悬浮体浓度年际变化明显,主要受长江入海水沙量年际变化的影响。长江口122.3°E以东海域表层悬浮体浓度的年际变化几乎不受长江入海泥沙的影响。风向对悬浮体浓度的扩散具有显著的作用,南风有利于高浓度悬浮体向外海扩散,东风则抑制扩展。     

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.     

Phosphorus speciation and availability in intertidal sediments of a temperate estuary: relation to eutrophication and annual P-fluxes

For a better understanding of the phosphorus dynamics and bioavailability in temperate climates, sequential chemical extraction techniques were used to study sediment P-pools distribution and relative importance in a eutrophicated estuary.Results indicate a shift in importance from the iron-bound P fraction to the CaCO₃-bound P fraction with increasing salinity, which suggests a decrease in bioavailable P from the most inner part of the estuary seaward, as the CaCO₃ associated P is believed to be less available for organisms. Salt marsh plants also influence sediment P speciation, through higher organic P fractions (mainly humic acid associated P) when compared to non-vegetated sediments. The ratio of iron-bound P to iron-oxyhydroxides may be used as an indicator of P availability, since it reflects the number of available P sorption sites in the metal oxides. This ratio was lowest in the intermediate zone of the estuary (13.7) when compared to the outer site (29.6) and the upper site (26.1), suggesting saturation of sorption sites. Co-incident with this, the intermediate site is characterized by the occurrence of macroalgal blooms during summer. In the present case, superficial sediments in the Mondego estuary do not show a clear seasonal trend, either in total amounts of exchangeable P or P speciation. Pools of exchangeable P in the surface sediment were 30 times higher than the annual net-export of P (14 ton year⁻¹) from the estuary. The annual P release from the sediment appears diminutive in comparison with the pool-size. Management measures to reduce nutrient input into coastal water systems should therefore consider that phosphorus availability may persist as a result of sediment supply, even after reducing the external point sources.     

河口及莱州湾沉积物中磷的化学形态及其含量

对13个河口站位的沉积物以及莱州湾两个站位的柱状沉积物中的磷的三种基本结合态进行了测定。结果表明：河口沉积物中总磷量与河流污染程度有关。磷的主要存在形态是以磷灰石结合态磷（PAI）存在的无机结合态磷（PIN）。莱州湾的柱状沉积物磷含量以及存在形态在离岸近和表层站位受到河流一定程度的影响，而在深层和离岸远的站位受河流影响的程度降低，各种形态的磷含量已趋于平衡。     

缢蛏(Sinonovacula constricta)生物扰动对养殖废水处理系统中沉积物磷赋存形态垂直分布的影响

为研究缢蛏(Sinonovacula constricta)生物扰动在养殖废水生态处理系统中对沉积物不同垂直分层的各种磷形态迁移转化的影响,于2016年5—7月在养殖废水处理池的贝藻处理区采集不同缢蛏养殖密度下的实验围隔箱内的底泥,测定不同垂直方向上的磷形态、微生物活性(FDA)以及碱性磷酸酶活性(APA)。结果表明,在底栖动物缢蛏生物扰动作用下,改变了沉积物内部的微环境,促进了微生物的生长,增大了沉积物中总微生物活性以及碱性磷酸酶活性。而沉积物中有机磷(OP)含量显著减少(P0.05);非磷灰石态无机磷(NAIP)、磷灰石态无机磷(AP)和无机磷(IP)含量显著增加(P0.05),这表明在缢蛏的生物扰动下OP可能转变成为AP、NAIP等无机磷成分;总磷含量呈降低趋势。本试验结果表明,缢蛏生物扰动下对于养殖废水生态处理系统沉积物垂直方向上的磷赋存形态具有显著的影响,且高密度组的生物扰动作用对沉积物中磷形态迁移转化的影响强于低密度组。     

Phosphorus in Bottom Sediments of Pomeranian Bay (Southern Baltic—Poland)

The paper presents the results of determination of inorganic and organic forms of phosphorus in bottom sediments of Pomeranian Bay. The sediments were collected in March and July of 1996. The following characteristics of the sediments were determined: organic matter content, forms of inorganic phosphorus: loosely adsorbed phosphorus and phosphorus bound to aluminium, calcium and iron, as well as total inorganic phosphorus. Pomeranian Bay is a shallow basin, with depth averaging between 12 and 15 m and sandy sediments prevailing. Smaller silt fractions occur only in the vicinity of the wina River estuary and in deeper northern regions of the Bay. Calcium-bound phosphorus is the dominant form of inorganic phosphorus in the Pomeranian Bay. Iron-bound phosphorus is the second most prevailing form, and aluminium-bound phosphorus the third. Loosely bound phosphorus was present in the lowest amounts. Total inorganic phosphorus in the Bay consisted of the four forms listed above, except in estuarine regions where an additional form of phosphorus occurred, most probably occluded phosphorus. High organic phosphorus concentrations were found at the wina River estuary and in the northern part of the Bay (Saßnitz Deep) corresponding to the higher organic matter content of these sediments. Sediments of Pomeranian Bay contained less phosphorus than those from the Gulf of Gda sk or Puck Bay and other parts of the Baltic Sea, suggesting that the amount of phosphorus in the sediments was determined by a number of inter-related factors, such as sediment type, amount of organic matter, the chemical composition of the sediment and oxygen content of near-bottom water.     

长江口及邻近海域沉积物再悬浮对水体磷酸盐的影响的模拟研究

以长江口及邻近海域为研究区域,采用改进后的SEDEX法对沉积物中各形态磷的含量进行了分析,并通过模拟实验探讨了沉积物再悬浮对上覆水体磷酸盐浓度的影响。结果表明:碎屑磷（De-P）是沉积物磷的主要赋存形态,占总磷（TP）的50%以上;其次是可提取态有机磷（Or-P）和非活性有机磷（Re-P）;生物可利用磷（BAP）占总磷的比例约为21%,可提取态有机磷（Or-P）是生物可利用磷（BAP）的主要存在形态。沉积物再悬浮时,水体磷酸盐的浓度显著升高,说明沉积物再悬浮会引起沉积物中磷的释放;水体磷酸盐浓度升高主要源于沉积物中磷的释放,而间隙水的贡献较低。沉积物发生再悬浮时,厌氧条件相对于好氧条件,更有利于沉积物磷的释放。     

珠江河口悬浮泥沙遥感数据集

选择 1 995— 2 0 0 0年间NOAA系列卫星AVHRR遥感器获取的珠江口及其邻近海域可见光和近红外遥感数据 ,利用基于海面 遥感器光谱反射率斜率传递现象的悬浮泥沙遥感算法 ,建立珠江口及其邻近海域 1 5 2个时相的悬浮泥沙数据集 ,进行悬浮泥沙浓度分布和变动规律的特征累积频率悬浮泥沙浓度、均值与均方差统计。结果表明 ,珠江口河口浅滩是悬浮泥沙浓度的高值区。随着径流、潮流的相互关系的变动 ,珠江口的悬浮泥沙浓度具有明显的季节变化 ,内伶仃洋悬浮泥沙浓度季节变动幅度最大 ,而磨刀门外浑浊水体的延伸方向变动幅度最大。     

The distribution and flux of particulate matter in the Bideford River Estuary,Prince Edward Island,Canada

The temporal and spatial distribution of total and organic particulate matter is investigated in the Bideford River estuary. Particulate matter is homogenously distributed in both the water column and the surface sediment, due to high rates of resuspension and lateral transport. The measured mean sedimentation rate for the estuary is 183·5 g of particulate matter m^?2 day^?1, of which more than half is due to resuspension.The surface sediment of the estuary is quantitatively the dominant reservoir of organic matter, with an average of 902·5 g of particulate organic carbon (POC) m^?2 and 119·5 g of particulate organic nitrogen (PON) m^?2. Per unit surface area, the sediment contains 450 times more POC and 400 times more PON than the water column. Terrestrial erosion contributes high levels of particulate matter, both organic and inorganic, to the estuary from the surrounding watershed. Low rates of sediment export from the estuary result in the accumulation of the terrigenous material. The allochthonous input of terrigenous organic matter masks any relationship between the indigenous plant biomass and the organic matter.In the water column, a direct correlation exists between the organic matter, i.e. POC and PON, concentration and the phytoplankton biomass as measured by the plant pigments. Resuspension is responsible for the residual organic matter in the water column unaccounted for by the phytoplankton biomass.The particulate content of the water column and the surface sediment of the estuary is compared to that of the adjacent bay. Water-borne particulate matter is exported from the estuary to the bay, so that no significant differences in concentration are noted. The estuarine sediment, however, is five to six times richer in organic and silt-clay content than the bay sediment. Since sediment flux out of the estuary is restricted, the allochthonous contribution of terrigenous particulate matter to the bay sediment is minor, and the organic content of the bay sediment is directly correlated to the autochthonous plant biomass.     

桑沟湾磷循环

The phosphorus cycle is studied during 2013–2014 in the Sanggou Bay(SGB), which is a typical aquaculture area in northern China. The forms of measured phosphorus include dissolved inorganic phosphorus(DIP), dissolved organic phosphorus(DOP), particulate inorganic phosphorus(PIP), and particulate organic phosphorus(POP).DIP and PIP are the major forms of total dissolved phosphorus(TDP) and total particulate phosphorus(TPP),representing 51%–75% and 53%–80%, respectively. The concentrations and distributions of phosphorus forms vary among seasons relative to aquaculture cycles, fluvial input, and hydrodynamic conditions. In autumn the concentration of DIP is significantly higher than in other seasons(P0.01), and higher concentrations are found in the west of the bay. In winter and spring the phosphorus concentrations are higher in the east of the bay than in the west. In summer, the distributions of phosphorus forms are uniform. A preliminary phosphorus budget is developed, and shows that SGB is a net sink of phosphorus. A total of 1.80×10~7 mol/a phosphorus is transported into the bay. The Yellow Sea is the major source of net input of phosphorus(61%), followed by submarine groundwater discharge(SGD)(27%), river input(11%), and atmospheric deposition(1%). The main phosphorus sink is the harvest of seaweeds(Saccharina japonica and Gracilaria lemaneiformis), bivalves(Chlamys farreri),and oysters(Crassostrea gigas), accounting for a total of 1.12×10~7 mol/a. Burial of phosphorus in sediment is another important sink, accounting for 7.00×10~6 mol/a. Biodeposition by bivalves is the major source of phosphorus in sediment, accounting for 54% of the total.     

长江口内外表层沉积物中营养元素的分布特征研究

通过对长江口内外9个表层沉积物中不同形态碳、氮、磷含量的测定,得到了长江口内外表层沉积物中营养元素的分布特征,探讨了影响其分布的主要因素。长江口内外表层沉积物中的营养元素在河流段的分布波动较大,在口门附近海域分布较平缓。在三种营养元素中,IC、ON和IP分别为C、N、P的优势形态。在影响表层沉积物中营养元素分布的因素中,沉积物的粒度和上覆水体的盐度在其中起着重要的作用,同时还受到近岸排污和海洋生物生产的影响。     

Suspended-sediment response to pulses in river flow and semidiurnal and fortnightly tidal variations in a mesotidal estuary

The effects of the tidal regime and high river flows on the suspended sediment concentration field have been separated and the retention time of fluvial sediment has been determined. The study was carried out in the upper Sado estuary, Portugal, and included surveys at high and low tide in different semidiurnal tide ranges every month for 1 year, including contrasting freshwater discharge. DDT and its metabolites (DDD and DDE) were determined in the suspended sediment and in the whole soft tissues of oysters, and they have been used as tracers of the derived flood material in the upper estuary. The tide is responsible for the relatively slow relaxation time following a winter runoff event.     

Response of sediment dynamics in the York River Estuary,USA to tropical cyclone Isabel of 2003

Tropical Cyclone Isabel of 2003 generated large storm surge, strong waves, and subsequent river flooding in the York River Estuary, USA during its passage across the Chesapeake Bay region. A 3D model was used to investigate the changes of sediment concentration, sediment flux, and the recovery time of the York River Estuary to its naturally evolved condition without the storm. The results showed that two sediment concentration peaks appeared during the storm event. The first one was induced by the large upstream flow and waves during the storm surge rising period, and the later one was caused by the strong downstream flow during the descent of the storm surge. The advection, which was induced by the barotropic gradient, dominated the sediment flux during the storm event. The sediment fluxes increased by a factor of 100 during the rise and descent of the storm surge. A large amount of sediment that was transported into the estuary and eroded from the seabed during the rising of the storm surge was quickly transported out of the estuary during the descent of the storm surge. Waves played a key role in stirring the seabed and increasing the sediment concentration during the storm. Subsequent high freshwater inflow changed the sediment loading and hydrodynamics in the estuary, and thus, influenced the estuarine turbidity maximum (ETM) dynamics profoundly. The ETM moved downstream with the river flooding initially and returned upstream with the waning of river flooding and the re-establishment of gravitational circulation. The effect of river flooding on sediment concentration varied spatially and depended on the changes of ETM locations and vertical mixing. The model results suggest that a large amount of sediment was transported out of the estuary during the storm event and the subsequent river flooding had a larger impact on recovery time of the estuary.