人类活动影响下的龙口海岸带海底地下水排泄通量研究

在沿海地区,以²²³Ra和²²⁴Ra为示踪剂建立的镭质量平衡模型已广泛应用于海底地下水排泄量(SGD)的研究中,然而目前国内外关于在人类活动复杂影响较大情况下的SGD研究却极为少见。本文对比研究了在有防渗墙(A区)和填海造陆(B区)两种不同人为因素影响下的龙口海岸带水体表现年龄、海底地下水排泄量及其携带的氮磷营养盐通量。结果表明,A区平均水体表现年龄为14.26 d,B区平均水体表现年龄为10.64 d。此外,B区沿岸地下水以及近岸海水中的Ra活度均普遍高于A区,而盐度低于A区。在SGD方面,A区的SGD速率为1.26~1.60 cm·d^-1,B区为1.43~1.82 cm·d^-1,考虑SGD在评估方法上存在一定的误差,因此两个区域的SGD速率相差不大。但与我国其他自然海域相比,这两个区域的SGD速率均处于较低水平。此外,B区的氮磷营养盐浓度普遍高于A区,而且由SGD驱动的氮磷营养盐通量不同,地下水输入的不平衡的营养盐极易改变龙口海域的营养盐结构,对海洋生态环境产生不利影响,这也进一步证实SGD在沿海生态环境以及水体污染治理中的重要地位。     

Nutrient and Radium Fluxes from Submarine Groundwater Discharge to Port Royal Sound, South Carolina

Water exchange between the coastal ocean and underlying aquifers provides a newly-recognized source of materials to the ocean. The flux of materials into the ocean from this process is termed submarine groundwater discharge (SGD). Both surficial and semi-confined aquifers contribute to SGD. Here we use ²²⁶Ra and ²²⁸Ra to quantify fluxes of SGD to Port Royal Sound, South Carolina, and to separate fluxes from the Upper Floridan (UFA) and surficial aquifers. Higher activity ratios of ²²⁸/²²⁶Ra in the surficial aquifer make this separation possible. We estimate total SGD fluxes of about 100 m³ s^-1 with about 80% being derived from the surficial aquifer. The SGD flux provides about1.8 × 10⁶ mol d^-1 of NH4 with almost 90% from the surficial aquifer. Because of strong differences in the concentration of PO4 within the UFA, PO₄ fluxes areless certain. Using the UFA wells with low PO₄ concentrations yields a flux of 1.2 × 10⁵ mol d^-1; using wells with high concentrations yields a flux of 2.0 × 10⁵ mol d^-1. In the first case virtually all of the PO₄ flux is from the surficial aquifer; in the second case, 40% is from the UFA.The UFA in this region has experienced dramatic changes as a result of withdrawals for human use. Prior to these withdrawals, total nutrient fluxes from the UFA may have been even larger. These changes in the UFA and similar coastal aquifers worldwide have the potential to significantly alter a major nutrient source for the coastal ocean.     

Submarine Groundwater Discharge-Derived Nutrient Loads to San Francisco Bay: Implications to Future Ecosystem Changes

Submarine groundwater discharge (SGD) was quantified at select sites in San Francisco Bay (SFB) from radium (²²³Ra and ²²⁴Ra) and radon (²²²Rn) activities measured in groundwater and surface water using simple mass balance box models. Based on these models, discharge rates in South and Central Bays were 0.3?C7.4?m³?day^?1?m^?1. Although SGD fluxes at the two regions (Central and South Bays) of SFB were of the same order of magnitude, the dissolved inorganic nitrogen (DIN) species associated with SGD were different. In the South Bay, ammonium (NH ₄ ⁺ ) concentrations in groundwater were three-fold higher than in open bay waters, and NH ₄ ⁺ was the primary DIN form discharged by SGD. At the Central Bay site, the primary DIN form in groundwater and associated discharge was nitrate (NO ₃ ^? ). The stable isotope signatures (??¹⁵N_NO3 and ??¹⁸O_NO3) of NO ₃ ^? in the South Bay groundwater and surface waters were both consistent with NO ₃ ^? derived from NH ₄ ⁺ that was isotopically enriched in ¹⁵N by NH ₄ ⁺ volatilization. Based on the calculated SGD fluxes and groundwater nutrient concentrations, nutrient fluxes associated with SGD can account for up to 16?% of DIN and 22?% of DIP in South and Central Bays. The form of DIN contributed to surface waters from SGD may impact the ratio of NO ₃ ^? to NH ₄ ⁺ available to phytoplankton with implications to bay productivity, phytoplankton species distribution, and nutrient uptake rates. This assessment of nutrient delivery via groundwater discharge in SFB may provide vital information for future bay ecological wellbeing and sensitivity to future environmental stressors.     

用镭-226示踪胶州湾的海底地下水排泄

海底地下水排泄（SGD）是全球水循环的一个组成部分,其输送的溶解物质不仅参与海洋的生物地球化学循环,而且影响近岸海域的生态环境。为了评估胶州湾海底地下水排泄状况,通过建立胶州湾内海水中²²⁶Ra的质量平衡模型来计算海底地下水排泄通量。胶州湾海水中²²⁶Ra的源主要有河流的输入、沉积物扩散输入和地下水的输入,海水系统在稳定状态下,这几种源应该与湾内海水和湾外海水的混合损失达到平衡。除了将地下水输入作为未知项外,对其他源和汇逐个进行量化,计算得知：2011年9-10月胶州湾的海底地下水排泄通量为7.85×10⁶ m³·d^-1;2012年4-5月胶州湾的海底地下水排泄通量为4.72×10⁶ m³·d^-1。在此基础上,对地下水输入胶州湾的营养盐进行了评价。     

Assessment of Submarine Groundwater Discharge (SGD) as a Source of Dissolved Radium and Nutrients to Moorea (French Polynesia) Coastal Waters

Previous work has documented large fluxes of freshwater and nutrients from submarine groundwater discharge (SGD) into the coastal waters of a few volcanic oceanic islands. However, on the majority of such islands, including Moorea (French Polynesia), SGD has not been studied. In this study, we used radium (Ra) isotopes and salinity to investigate SGD and associated nutrient inputs at five coastal sites and Paopao Bay on the north shore of Moorea. Ra activities were highest in coastal groundwater, intermediate in coastal ocean surface water, and lowest in offshore surface water, indicating that high-Ra groundwater was discharging into the coastal ocean. On average, groundwater nitrate and nitrite (N + N), phosphate, ammonium, and silica concentrations were 12, 21, 29, and 33 times greater, respectively, than those in coastal ocean surface water, suggesting that groundwater discharge could be an important source of nutrients to the coastal ocean. Ra and salinity mass balances indicated that most or all SGD at these sites was saline and likely originated from a deeper, unsampled layer of Ra-enriched recirculated seawater. This high-salinity SGD may be less affected by terrestrial nutrient sources, such as fertilizer, sewage, and animal waste, compared to meteoric groundwater; however, nutrient-salinity trends indicate it may still have much higher concentrations of nitrate and phosphate than coastal receiving waters. Coastal ocean nutrient concentrations were virtually identical to those measured offshore, suggesting that nutrient subsidies from SGD are efficiently utilized.     

镭同位素示踪隆教湾的海底地下水排泄

福建省漳州市隆教湾海水中镭同位素的研究,目的是评价海底地下水排泄量。在2007年6月的航次中,垂直于岸线的9km剖面上布置15个站位,每个站位用潜水泵采集表层海水样60L于塑料桶中。水样运回实验室后,立即用装有锰纤维的PVC管以虹吸的方式富集水样中的镭同位素,水通过PVC管的流速小于300ml/min。224Ra活度用连续射气法测定,测完224Ra后密封7d以上,然后用直接射气法测定226Ra活度。224Ra和226Ra活度都呈现自岸向海逐渐降低的规律,表明扩散控制镭同位素的分布,由224Ra获得68.83km2d-1的扩散系数,同时226Ra形成-0.963dpm100l-1km-1的活度梯度。用扩散系数和活度梯度建立的226Ra的离岸通量为6.62×1011dpmkm-2d-1,这个通量一定是得到SGD输入的镭支持,从而获得隆教湾的海底地下水排泄量是3.03×109m3km-2d-1。该排泄量包括陆源地下淡水排泄量和再循环海水排泄量,绝大部分可能是再循环海水,有待进一步研究。     

用氡-222评价五缘湾的地下水输入

海底地下水排泄(SGD)近年来成为陆-海相互作用的研究热点,地球化学示踪方法是其主要研究手段,尝试用天然示踪剂氡-222评价厦门五缘湾的SGD。为了评价五缘湾SGD的入海通量及其变化,对五缘湾海水中²²²Rn和²²⁶Ra活度、大气中²²²Rn活度、风速、水温和水深进行了连续2 d的测量,对沉积物进行了培养实验用以获得其²²²Rn扩散通量和孔隙水中²²²Rn活度。基于海水中²²²Rn通量的质量平衡,对实测的海水中²²²Rn活度实施了母体支持、涨落潮影响、大气逃逸损失、沉积物扩散输入、混合损失的校正,保守估计SGD输入的²²²Rn通量在0~126.7 Bq/(m²·h)范围内变化,对海水中²²²Rn的平均贡献达54%。以井水和孔隙水中²²²Rn的加权平均值作为SGD端元的代表,获得SGD的输入速率为0~29.3 cm/d,平均输入速率9.3 cm/d。SGD输入速率的动态变化基本围绕12 h的周期波动,是对本海域正规半日潮的具体响应。假设SGD以平均速率在五缘湾海底输入,则五缘湾海底的SGD输入量为1.86×10⁵ m³/d。以陆源地下淡水占SGD输入量的10%考虑,五缘湾的陆源地下淡水输入量约为1.86×10⁴ m³/d。     

Submarine Groundwater Discharge Estimates Using Radium Isotopes and Related Nutrient Inputs into Tauranga Harbour (New Zealand)

Land-based pollutants such as fertilizers and wastewater can infiltrate into aquifers and discharge into surrounding coastal water bodies as submarine groundwater discharge (SGD). Oceanic islands, with a large coast length to land area ratio, may be hot spots of SGD into the global ocean. Although SGD may be a major pathway of dissolved nutrients, carbon and metals to coastal waters, studies have been limited due to the difficulties in measuring this often diffuse process. This study used radium isotopes (²²³Ra, ²²⁴Ra, ²²⁶Ra) to investigate SGD and the associated fluxes of nutrients into Tauranga Harbour, New Zealand. We calculated the apparent water mass ages of the harbour to be between ~4.1 and 7.8 days, which was similar to a previous numerical model of ~2–8 days. A ²²⁶Ra mass balance was constructed to quantify SGD fluxes at the harbour scale. A minimum SGD flux rate of 0.53 cm day^?1 was calculated by using the maximum groundwater end-member value from 22 sample sites. However, using the geometric mean from these samples as a representative end-member, a final value of 2.83 cm day^?1 or a flux of 3.09 × 10⁶ m³ day^?1 was calculated. These values were between ~1 and 2.8 times greater than all the major river and creeks discharging into the harbour during the sampling period. Due to the higher observed nutrient concentrations in groundwater, the SGD-derived dissolved inorganic nitrogen (DIN), dissolved organic nitrogen (DON) and total dissolved phosphorus (TDP) fluxes were calculated to be 1.07, 0.87 and 0.05 mmol m² day^?1, respectively. These SGD inputs were ~5 times (for nitrogen) and ~8 times (for phosphorus) greater than the input from surrounding rivers and streams. The average N:P ratio in groundwater samples was 36:1 (which was greatly in excess of the Redfield ratio of 16). The harbour water had a N:P ratio of ~17:1. A positive relationship between radium isotopes and N:P ratios in the harbour further supported the hypothesis that SGD can have major implications for primary production, including recurrent algal bloom events which occur in the harbour. We suggest SGD as a major driver of nutrient dynamics in Tauranga Harbour and potentially other similar coastal lagoon systems and estuaries on oceanic islands.     

Variations of Hydrodynamics and Submarine Groundwater Discharge in the Yellow River Estuary Under the Influence of the Water-Sediment Regulation Scheme

The “Water-Sediment Regulation Scheme” (WSRS) is critically important to the hydrologic evaluation of the Yellow River estuary since a huge pulse of water and sediment are delivered into the sea during a short period. We used the natural geochemical tracers radium (²²³Ra, ²²⁴Ra, ²²⁶Ra) and radon (²²²Rn) isotopes as well as other hydrological parameters to investigate the mixing variations and submarine groundwater discharge (SGD) in the Yellow River estuary under the influence of the 2013 WSRS. Dramatically elevated radium and radon isotopic activities were observed during this WSRS compared with activities measured during a non-WSRS period. Radium “water ages” indicated that the offshore transport rate nearly tripled when the river discharge increased from 400 to 3400 m³/s. We calculated the SGD flux in the Yellow River estuary based on a radium mass balance model as well as radium and radon time-series models. The SGD flux was estimated at 0.02~0.20 m/day during a non-WSRS period and 0.67~1.22 m/day during the 2013 WSRS period. The results also indicate that large river discharge tends to lead more intense SGD along the river channel direction with a large amount of fresh SGD.     

国内外地下水入海通量研究现状与趋势

地下水向海排泄是海陆相互作用的重要过程,它可能是陆地污染物质和营养盐排放入海的重要通道,会对近岸的海域环境产生一定的影响。它已在国外受到相当多的重视,而我国的相关研究还很少见。文中介绍了该领域的三种主要方法:原位测量方法、模型技术和示踪技术,且探讨了其发展方向及趋势。     

Tidal pumping drives nutrient and dissolved organic matter dynamics in a Gulf of Mexico subterranean estuary

We hypothesize that nutrient cycling in a Gulf of Mexico subterranean estuary (STE) is fueled by oxygen and labile organic matter supplied by tidal pumping of seawater into the coastal aquifer. We estimate nutrient production rates using the standard estuarine model and a non-steady-state box model, separate nutrient fluxes associated with fresh and saline submarine groundwater discharge (SGD), and estimate offshore fluxes from radium isotope distributions. The results indicate a large variability in nutrient concentrations over tidal and seasonal time scales. At high tide, nutrient concentrations in shallow beach groundwater were low as a result of dilution caused by seawater recirculation. During ebb tide, the concentrations increased until they reached a maximum just before the next high tide. The dominant form of nitrogen was dissolved organic nitrogen (DON) in freshwater, nitrate in brackish waters, and ammonium in saline waters. Dissolved organic carbon (DOC) production was two-fold higher in the summer than in the winter, while nitrate and DON production were one order of magnitude higher. Oxic remineralization and denitrification most likely explain these patterns. Even though fresh SGD accounted for only ∼5% of total volumetric additions, it was an important pathway of nutrients as a result of biogeochemical inputs in the mixing zone. Fresh SGD transported ∼25% of DOC and ∼50% of total dissolved nitrogen inputs into the coastal ocean, with the remainder associated with a one-dimensional vertical seawater exchange process. While SGD volumetric inputs are similar seasonally, changes in the biogeochemical conditions of this coastal plain STE led to higher summertime SGD nutrient fluxes (40% higher for DOC and 60% higher for nitrogen in the summer compared to the winter). We suggest that coastal primary production and nutrient dynamics in the STE are linked.     

近岸海域^226Ra的时空变化与海底地下水排泄（SGD）估算

海底地下水排泄（submarine groundwater dischurge,SGD）是沿海地区陆地物质向海洋输送的重要途径,中国具有漫长的海岸线．准确地评估我国沿海地区的SGD及其对沿海海洋生态环境的潜在影响具有重要的理论与实践意义。本文以浙江舟山朱家尖海湾为研究区域,通过冬、夏两季地下水和海水的同步采样分析,在研究地下水和海水中镭（^226Ra）时空变化的基础上,利用^226Ra的质量平衡原理,估算了研究区内SGD的通量为240×10^5～230×10^6m^3／d,根据12月份枯水期推算的全年保守通量为864×10^7～828×10^8m^3／a,另外,根据年平均降水量等水文参数估算的氮、磷和硅营养盐年平均的入海通量分别为3.256t／a、0.029t／a和52.775t／a。     

海底地下水排放:重要的海岸带陆海相互作用过程

沿海地区海底地下水排放在北美和欧洲等发达地区受到了越来越多的重视,被认为是一个重要的海岸带陆海相互作用过程。但这一过程在我国尚未引起足够认识,有关研究极少见。海底地下水排放的研究历史不长,只是近十多年才有了快速的发展,有了越来越多的定量研究成果。其研究方法主要有水文计算法、现场实测法和地球化学示踪法,各种方法之间的对比实验是目前的热点问题。沿海地下水排放具有重要的环境意义,它可以是陆地营养物质和污染物质的一个重要排放通道,可以对海岸带环境产生一定影响。我国沿海地区应该加强有关的研究工作,为海岸带环境管理作出贡献。     

Scales of nutrient-limited phytoplankton productivity in Chesapeake Bay

The scales on which phytoplankton biomass vary in response to variable nutrient inputs depend on the nutrient status of the plankton community and on the capacity of consumers to respond to increases in phytoplankton productivity. Overenrichment and associated declines in water quality occur when phytoplankton growth rate becomes nutrient-saturated, the production and consumption of phytoplankton biomass become uncoupled in time and space, and phytoplankton biomass becomes high and varies on scales longer than phytoplankton generation times. In Chesapeake Bay, phytoplankton growth rates appear to be limited by dissolved inorganic phosphorus (DIP) during spring when biomass reaches its annual maximum and by dissolved inorganic nitrogen (DIN) during summer when phytoplankton growth rates are highest. However, despite high inputs of DIN and dissolved silicate (DSi) relative to DIP (molar ratios of N∶P and Si∶P>100), seasonal accumulations of phytoplankton biomass within the salt-intruded-reach of the bay appear to be limited by riverine DIN supply while the magnitude of the spring diatom bloom is governed by DSi supply. Seasonal imbalances between biomass production and consumption lead to massive accumulations of phytoplankton biomass (often>1,000 mg Chl-a m^?2) during spring, to spring-summer oxygen depletion (summer bottom water <20% saturation), and to exceptionally high levels of annual phytoplankton production (>400 g m^?2 yr^?1). Nitrogen-dependent seasonal accumulations of phytoplankton biomass and annual production occur as a consequence of differences in the rates and pathways of nitrogen and phosphorus cycling within the bay and underscore the importance of controlling nitrogen inputs to the mesohaline and lower reaches of the bay.     

Characterising the distribution of near-shore submarine groundwater discharge along a coastline using 222Rn and electrical conductivity

The spatial and temporal distribution of near-shore fresh submarine groundwater discharge (SGD) was characterised from the coastal aquifers of the Willunga Basin, South Australia, an extensive aquifer system that supports an important viticultural region. Measurements of electrical conductivity (EC) and ²²²Rn (radon) activity were collected at 19 sites along the coastline during the Southern Hemisphere spring (2011) and summer (2013). At each site, samples were collected from the surf zone as well asporewater from beach sediment in the intertidal zone. Surf-zone radon activity ranged from <5 to 70mBq L^–1, and intertidal porewater radon ranged over two orders of magnitude (220–36 940 mBq L^–1) along the Willunga Basin coastline during both surveys. Overall, surf-zone and porewater EC was lower in the spring 2011 survey than in the summer 2013 survey. Porewater EC was similar to that of coastal water at most sites along the coastline, except at three sites where porewater EC was found to be lower than coastal water during both surveys, and three sites where evaporated seawater was observed in the summer survey. Based on the patterns in radon and EC along the coastline, two sites of localised fresh SGD were identified, in addition to a groundwater spring that is known to discharge to the coast. The results indicate that near-shore fresh SGD occurs as localised seeps rather than diffuse seepage along the entire coastline. The apparent absence of groundwater discharge at most locations is also consistent with current evidence suggesting that extensive groundwater pumping within the basin has resulted in seawater intrusion across much of the coastline. These observations also suggest that previous studies are likely to have over-estimated SGD rates from the Willunga Basin because they assumed that SGD occurred along the entire coastline.     

Submarine groundwater discharge in a subsiding coastal lowland: A Ra and Rn investigation in the Southern Venice lagoon

Several recent studies have suggested that submarine groundwater discharge (SGD) occurs in the Venice lagoon with discharge rates on the same order or larger than the surface runoff, as demonstrated previously in several other coastal zones around the world. Here, the first set of ²²²Rn data, along with new ²²⁶Ra data are reported, in order to investigate the occurrence and magnitude of SGD specifically in the southern basin of the lagoon. The independent connection with the Adriatic Sea (at the Chioggia inlet), in addition to the relative isolation of the water body from the main lagoon, make this area an interesting case study. There is probably only minimal fresh groundwater flux to the lagoon because the surrounding aquifer is subsiding and mainly has a lower hydraulic head than seawater.The data show that the Ra and Rn activities are in slight excess in the lagoon compared to the open sea, with values on the same order as those observed in the northern and central basins. Taking into account the water exchange rate between the lagoon and adjacent seawater provided by previous hydrodynamic numerical modelling, it is shown that this excess cannot be supported at steady state by only riverine input and by diffusive release from the sediment interstitial water. High activities observed in groundwater samples collected from 16 piezometers tapping into the shallow aquifer over the coastal lowland substantiate that the excess radioactivity in the lagoon may indeed be due to the advection of groundwater directly into the lagoon bottom water through the sediment interface. However, the data show that the groundwater composition is extremely heterogeneous, with high Ra activities concentrated within a narrow coastal strip where the contact between fresh and saline water takes place, while Rn strongly decreases when approaching the lagoon shore across the 20 km coastal plain. Assuming that the average groundwater activities measured in the coastal strip are representative of the SGD composition, a SGD flux of 7.7 ± 3.5 × 10⁵ and 2.5 ± 2 × 10⁶ m³/d is calculated using a ²²⁶Ra and ²²²Rn budget, respectively, (i.e. about 1-3 times the surface runoff), substantially lower than in previous studies. The influence of all assumptions on SGD estimates (groundwater heterogeneity, diffusive sediment flux, one-box versus multi-boxes model calculations) is discussed, and a sensitivity analysis of the influence of imperfect exchange and mixing at the lagoon outlets that affects the lagoon composition is provided. Finally, the results confirm that the SGD flux, calculated with these assumptions, is largely (∼80%) composed of saline lagoon water circulating through the sediment under the lagoon margin, and that the fresh water discharge associated with SGD is at most a minor term in the lagoon hydrologic balance.     

Application of226Ra,228Ra,223Ra, and224Ra in coastal waters to assessing coastal mixing rates and groundwater discharge to oceans

The fate of dissolved material delivered to the coastal ocean depends on its reactivity and the rate at which it is mixed offshore. To measure the rate of exchange of coastal waters, we employ two short-lived radium isotopes,²²³Ra and²²⁴Ra. Along the coast of South Carolina, shore-perpendicular profiles of²²³Ra and²²⁴Ra in surface waters show consistent gradients which may be modeled to yield eddy diffusion coefficients of 350–540 m²s⁻¹. Coupling the exchange rate with offshore concentration gradients yields estimates of offshore fluxes of dissolved materials. For systems in steady state, the offshore fluxes must be balanced by new inputs from rivers, groundwater, sewers or other sources. Two tracers that show promise in evaluating groundwater input are barium and²²⁶Ra. These tracers have high relative concentrations in the fluids and low-reactivity in the coastal ocean. Applying the eddy diffusion coefficients to the offshore gradient of²²⁶Ra concentration provides an estimate of the offshore flux of²²⁶Ra. Measuring the concentrations of²²⁶Ra in subsurface fluids provides an estimate of the fluid flux necessary to provide the²²⁶Ra. These estimates indicate that the volume of groundwater required to support these fluxes is of the order of 40% of the surface water flow.     

Quantification of submarine groundwater discharge(SGD) using radon,radium tracers and nutrient inputs in Punnakayal,south coast of India

The present study focused on the estimation of submarine groundwater discharge(SGD)and the effects of nutrient fluxes due to the SGD process.The parameters of SGD such as magnitude,character,and nutrient flux in Punnakayal region of South East coast of India were evaluated using multiple tracers of groundwater inputs in 2019.It was found that the elevated values for the tracers in the study area,displayed a gradational change in the values as move from estuarine part to the offshore.Simultaneous occurrence of fresh and saline SGD is observed on the study sites.Also,indicated that the SGD fluxes ranged from 0.04 to 0.12 m^3 m^-2d^-1 at the estuary and0.03-0.15 m^3 m^-2d^-1at the groundwater site.A substantially increased value for 222 Rn activities is distinguished in the estuary to values over 312 dpm L^-1.Nutrient embellishments were generally greatest at locations with substantial meteoric elements in groundwater;however,the recirculation of saltwater through the geological formation could provide a way of transferring terrestrially-derived nutrients to the coastal zone at many places.     

Nutrient dynamics in the Pomeranian Bay (southern Baltic): Impact of the Oder River outflow

The Pomeranian Bay is a coastal region fed by the Oder River, one of the seven largest Baltic rivers, whose waters flow through a large and complex estuarine system before entering the bay. Nutrients (NO₃ ⁻, NO₂ ⁻, NH₄ ⁺, Ntot, PO₄ ³⁻, P_tot, DSi), chlorophylla concentrations, oxygen content, salinity, and temperature were measured in the Pomeranian Bay in nine seasonally distributed cruises during 1993–1997. Strong spatial and temporal patterns were observed and they were governed by: the seasonally variable riverine water-nutrient discharges, the seasonally variable uptake of nutrients and their cycling in the river estuary and the Bay, the character of water exchange between the Pomeranian Bay and the Szczecin Lagoon, and the water flow patterns in the Bay that are dominated by wind-driven circulation. Easterly winds resulted in water and nutrient transport along the German coastline, while westerly winds confined the nutrient rich riverine waters to the Polish coast and transported them eastward beyond the study area. Two water masses, coastal and open, characterized by different chemical and physical parameters and chla content were found in the Bay independently of the season. The role of the Oder estuary in nutrient transformation, as well as the role of temperature in transformation processes is stressed in the paper. The DIN:DIP:DSi ratio indicated that phosphorus most probably played a limiting role in phytoplankton production in the Bay in spring, while nitrogen did the same in summer. During the spring bloom, predominated by diatoms, the DSi:DIN ratio dropped to 0.1 in the coastal waters and to 0.6 in the open bay waters, pointing to silicon limitation of diatom growth, similar to what is being observed in other Baltic regions.     

海岸带水文地质学研究中的几个热点问题

对海岸带水文地质学中几个热点问题的研究现状和待解决的主要问题做了综述.主要包括如下几个方面:①海潮波动引起的滨海含水层系统地下水位波动的定量解析及其应用;②潮间带海水一地下水相互作用的定量模拟及其在海滩漏油污染治理中的应用;③滨海近岸包气带中海潮波动引起的地下水气两相流及其生态和工程效应;④海底地下水排泄量的定量估计.