Liaodong Bay Research Articles

Effects of Liaoning Hongyanhe Nuclear Power Plant on the Zooplankton Community in Summer of 2017

To evaluate the effects of the Hongyanhe Nuclear Power Plant on the zooplankton community in the surrounding seawater during summer, multiple environmental factors and zooplankton distribution along the east coast of Liaodong Bay were investigated in the summer of 2017. In particular, the influences of seawater temperature, salinity, and chlorophyll a (Chl a) on the zooplankton community were analyzed. Zooplankton abundances and Chl a concentrations along the east coast of Liaodong Bay showed an initial increase followed by a decrease from July to September. During the three months, the zooplankton abundance was the highest (8116.70 ind m−3) in August. The Shannon-Wiener index showed a downtrend from July to September, with the average value falling from 1.65 in July to 1.50 in September. Calanus sinicus, Paracalanus parvus, copepodid, and bivalve larvae were the dominant species/groups in the three months. The effects of the nuclear power plant’s outlet on the environment factors were mainly reflected in the increased seawater temperature. Redundancy analysis showed that the zooplankton community was jointly affected by seawater temperature, salinity and Chl a concentration, and the degree of this impact varied monthly. The impact of seawater temperature on the zooplankton community was stronger than that of salinity. The primary impact of the Hongyanhe Nuclear Power Plant on the structure and distribution of the zooplankton community in the surrounding seawater during the summer was increased seawater temperature, which caused a reduction in the abundance of dominant species/groups.

E&P Notes (September 2020)

Petrobras Slices Time, Cost of Post-Salt Drilling Lynnmarie P. Flowers, Technology Editor Petrobras has cut in half the time and cost of drilling some wells using its patented True One Trip Ultra Slender (TOTUS) concept. The technique can be used in certain mature fields of the postsalt where geological and reservoir characteristics favor its application. With TOTUS, the firm drilled a well in 44 days in early July, compared to the historic average of 96 days, resulting in a cost reduction of approximately 50% or $30 million. The development of post-salt wells offshore Brazil has been a challenging project. Faced with water depths of 2000-plus m - and a salt layer 2000 m thick - to reach reservoirs at 7000 m below sea level, Petrobras had the need to use novel technological and procedural techniques. Canada’s Oil Production Sinks to 2016 Levels In the first half of 2020, Canada’s production declined 20% from its 2019 average of 5.5 million B/D as a result of low crude oil prices, reduced demand, and continued production curtailments imposed by the government of Alberta. Last year, when Canada was the world’s fourth-largest producer, the province accounted for more than 80% of its production. Canada produced about the same amount of petroleum and other liquids in 2019 as it did in 2018, when western Canadian select crude oil was trading at historically low prices. The government of Alberta imposed production curtailments in early 2019 to reduce associated bitumen production and reduce inventories and growing constraints on export pipeline capacity. These restrictions were extended through the end of this year. MOL Pakistan Discovers Gas and Condensate As the operator of the TAL Block in Pakistan, MOL has made a new gas and condensate discovery at the Mamikhel South-1 exploratory well. This marks the company’s thirteenth discovery in Pakistan, its tenth in the TAL Block, and the second time in 3 months to discover hydrocarbon reserves. In March, MOL Norge discovered oil and gas in the North Sea. MOL has made 13 oil, gas, and condensate discoveries in Pakistan since 2000 including over 400 million BOE hydrocarbon reserves. It is responsible for 89 million BOED gross production (as of Q1 2020) in the TAL Block, where it has an 8.4% share. DTEK To Conduct Large-Scale Green Seismic Exploration DTEK Oil & Gas this year will conduct a large-scale seismic survey using green technology on a gas-and-condensate field in Ukraine. The recording of seismic data in real time will allow DTEK to assess the quality of data logged during execution, increasing the quality of geophysical information recorded during the course of work. The cordless “green seismic” technology is connected via wireless systems in lieu of cables, enabling the exploration of complex and previously inaccessible landscapes, shortening project-completion time, and reducing environmental impact. The technology does not require special heavy machinery for installation. Supreme Court Ruling on Oklahoma Tribal Land Raises Questions for Oil Industry A US Supreme Court decision recognizing about half of Oklahoma as Native American reservation land has implications for oil and gas development and raises regulatory and tax questions that could take years to settle. On 9 July, the court overturned an Oklahoma tribe member’s criminal conviction - in the McGirt v. Oklahoma decision - because the crime was com-mitted on reservation land and therefore outside the reach of state criminal law. CNOOC Starts Production From Luda Project Exploration and production independent CNOOC has produced first oil from its Luda 21-2/16-3 regional development in the Bohai Sea, offshore China. The project currently contains one central platform, three wellhead platforms, and one production platform. CNOOC expects to drill 69 development wells; peak production is expected to reach 25,600 B/D in 2022. Situated about 25 miles north of the Luda 10-1 oil field and 55 miles northwest of the Suizhong 36-1 onshore terminal, the Liaodong Bay development is operating in an average water depth of 82 ft. Cairn Sells Senegal Interest to Lukoil Russia’s Lukoil will sell its entire 40% interest in the Rufisque, Sangomar, and Sangomar Deep (RSSD) contract area to Edinburgh oil and gas producer Cairn Energy for up to $400 million. Lukoil intends to return at least $250 million to shareholders as a special dividend after the sale. The blocks of the project covering 2212 km2 are located on the deepwater shelf of the Republic of Senegal 80 km from the shore with the sea depth of 800-2175 m. The blocks include two discovered fields, Sangomar and FAN. The cash consideration payable on completion is $300 million, and up to $100 million depending on the timing of first oil and the average Brent oil price in the first 6 months of production.

Phytoplankton biomarkers in surface sediments from Liaodong Bay and their potential as indicators of primary productivity

This paper reported the distribution of phytoplankton biomarkers in surface sediments of Liaodong Bay, Bohai Sea. The primary productivity indicated by biomarkers is consistent with the results from modern water column phytoplankton surveys, indicating that the biomarkers can be used to reconstruct the primary productivity. The productivity in the bay mouth is higher than in the shallow coast area, indicating that the main controlling factor is the turbidity rather than terrestrial nutrients. The high primary productivity near Juhua Island is mainly related to eutrophication caused by human culture and land-based sewage discharge. The relative proportion of biomarkers showed that diatom and dinoflagellate contributed more to the coastal area and were mainly related to the competitive advantage under the condition of high nutrient salts, while a high proportion of haptophytes was found in the middle, which corresponded to the high salinity water.

Efficient tidal channel networks alleviate the drought-induced die-off of salt marshes: Implications for coastal restoration and management

Massive die-off in salt marshes is one of the most common examples of widespread degradation in marine and coastal ecosystems. In salt marshes, tidal channel networks facilitate the exchange of water, nutrients, sediments and biota with the open marine environments. However, quantitative analyses of the role of channel networks in alleviating vegetation die-off in salt marshes are scarce. Here we quantified the spatial-temporal development of marsh vegetation die-off in the northern Liaodong Bay by analyzing aerial images before, during, and after a drought (from 2014 to 2018). We found that Suaeda salsa marshes have recently experienced large-scale die-off. The extent of vegetation die-off increases with increasing distance from the channel network. Moreover, our results suggested that efficient tidal channel networks (high drainage density, low mean unchanneled path length) can mitigate die-off at the watershed scale. We presented possible abiotic & biotic processes in channel networks that explain this spatial dynamic. Our study highlights the importance of efficient tidal channel networks in mitigating die-off and enhancing the resistance of marshes to droughts, and call for incorporating theses dynamics in coastal restoration and management.

Forecast of the Change Tendency of Sea Ice Extent in Liaodong Bay

Since massive sea ice occurs in the sea area of Liaodong Bay area, sea ice products are greatly demanded by offshore drilling platforms, marine transportation and coastal aquaculture. It is imperative to develop from sea ice monitoring to live + forecast of development tendency. An one-month latency response can be found between the maximum sea ice extent and the minimum average temperature as per their relationship. Hence, analysis on the latency correlation has been conducted through constructing sea ice tendency forecasting models for the sea ice developing and melting stages. According to the result, the negative accumulated temperature is a favorable forecasting factor since sea ice in Liaodong Bay is affected by the accumulated change of previous temperature factor. Besdies, the sea ice extent is significantly correlated with the accumulated freezing temperature of ≤-2°C in the sea ice developing stage. And in the melting stage, the average maximum temperature of 11 days has the most significant correlation. What’s more, as the accumulated temperature change rate is similar to the fluctuation of curve of the sea ice extent, the accuracy of the forecast model is climbed to 79% upon studying the relationship between the difference and the accumulated temperature change rate of the forecast model and the sea ice monitoring extent.

Modal Parameters Identification of A Real Offshore Platform From the Response Excited by Natural Ice Loading

This paper investigates the possibility of utilizing response from natural ice loading for modal parameter identification of real offshore platforms. The test platform is the JZ20-2MUQ jacket platform located in the Liaodong Bay, China. A field experiment is carried out in winter season, as the platform is excited by floating ices. The feasibility is demonstrated by the acceleration response of two different segments. By the SSI-data method, the modal frequencies and damping ratios of four structural modes can be successfully identified from both segments. The estimated information from both segments is almost identical, which demonstrates that the modal identification is trustworthy. Furthermore, by taking the Jacket platform as a benchmark, the numerical performance of five popular time-domain EMA methods is systematically compared from different viewpoints. The comparisons are categorized as: (1) stochastic methods versus deterministic methods; (2) high-order methods versus low-order methods; (3) data-driven versus covariance-driven stochastic subspace identification methods.

Impact of Large-Scale Reclamation on Resources and Environment in West Liaodong Bay and Remediation and Restoration Suggestions—A Case Study of Xingcheng Coastal Industrial Area

Based on the case study of reclamation in west Liaodong Bay in Xingcheng City, this paper analyzes the construction background and implementation process of reclamation in the coastal industrial area, and assesses the major resource and environmental issues arising from reclamation. Since the reclamation of Xingcheng Coastal Industrial Area has caused the losses of lagoon coastal wetlands, coastline resources, hydrodynamic environment of islands and reefs and ecology as well as the changes of hydrodynamic and scouring and silting environment in local sea areas. The paper suggests that measures, such as watercourse and coast remediation and restoration, coastal wetland restoration, hydrodynamic recovery of islands and reefs, water system construction, reproduction and release, should be taken to mitigate the adverse impact of reclamation on resources and the environment to a certain extent.

Spatio-temporal distribution of plastic and microplastic debris in the surface water of the Bohai Sea, China

As an emerging marine environmental issue, marine plastic debris pollution has attracted worldwide attention. Studies have covered more and more areas of the world's oceans. To further understand the sources and variation of marine plastic debris in the surface water of the Bohai Sea, in this study, plastic debris was collected during the four seasons of 2016–2017. The results showed the mean density of plastic debris over these seasons was 0.49 ± 0.18 particles/m3. Macro-, meso-, and micro- plastics accounted for 5%, 26%, and 69% of the total number of plastic debris, respectively. The density of the microplastics was 0.35 ± 0.13 particles/m3. The highest density was found in spring, followed by summer and winter, and the lowest in autumn. High distribution densities were observed in the Liaodong Bay and the Bohai Strait, which were attributed to the dynamics of the rim current, terrain, and fishery activities. Capsule abstractRiverine input, dynamics of the rim current, terrain, and fishery activities contribute to the variations in marine plastic debris in the surface water of the Bohai Sea.

Sedimentology of the deltaic Paleogene Shahejie Formation in the D‐1 area of Liaodong Bay, East China

The Liaodong Bay area in north‐east China has abundant hydrocarbon resources. The study area (referred to as D‐1) is located in the south‐east portion of the Liaodong Graben, a tectonic unit of Liaodong Bay, where the focus for exploration is on sandstone units in the Palaeogene Shahejie Formation. Here, hydrocarbons with an oil production capacity of 629 m3/day have been discovered in well D‐1‐2SA. The reservoir facies have been analysed by combining the cuttings, logging, seismic data, sedimentary facies, and sequence stratigraphy. In the sequence stratigraphic study, the second member from the base of the formation is divided into one third‐ and four fourth‐order depositional sequences. The sedimentary facies include fan deltaic, braided river deltaic, and lagoonal systems. Seismic attribute inversion of the sequence framework, depositional models, and sediment distribution has been conducted for each system tract. The reservoirs facies in the D‐1 area are characterized by medium to low porosity, and medium to low permeability. The development of reservoirs facies is related to the subaqueous depositional channels of the fan deltaic system with the best quality for hydrocarbon storage. These channels have strong root mean square amplitudes used for seismic attribute identification for reservoir targets. The formations of the source‐to‐sink system with granitic and metamorphic source rocks and relative distant transportation are considered to have the best potential for hydrocarbon reservoirs.

Tintinnid community throughout the Bohai Sea during the spring

As one of the important microzooplankton in marine pelagic habitats, tintinnids are classified as neritic genera, oceanic genera and cosmopolitan genera. Until now, we know little about the interaction between neritic and oceanic genera in continental shelves. Low species richness area was found in the mixing area between neritic and oceanic genera in the East China Sea. In this study, we investigated the spatial distribution of tintinnid community throughout the entire Bohai Sea in May (spring) of 2014 to find out: (1) whether the tintinnid assembalges differed in the three major bays bordering this shallow inland sea; (2) whether there was low species richness area in the Bohai Sea. Three genera and 11 species attributed to neritic and cosmopolitan taxa were reported from this region. Tintinnid abundance averaged (81±216) ind./L (0–1 234 ind./L). Tintinnid community differed within the three major bays, with each characterized by different tintinnid taxa. Referring to the average abundance of three bays, tintinnids were most abundant in the Laizhou Bay ((328±445) ind./L), and least abundant in the Liaodong Bay ((34±57) ind./L). A low species richness area occurred in the central Bohai Sea (20–40 m isobaths), in some stations of which no tintinnid was recorded. Our study demonstrates that tintinnid community varied greatly over small spatial scales, and low species richness area was found in the mixing area between neritic and oceanic genera within this inland sea.

Spatial distribution, control factors and sources of heavy metal in the surface sediments of Fudu Estuary waters, East Liaodong Bay, China

To investigate the sediment quality of Fudu Estuary waters in East Liaodong Bay, the grain size, concentrations of total organic carbon (TOC) and heavy metal (Cr, Cu, Zn, As, Cd, Pb) of 25 surface sediments were tested. The concentration of heavy metals was found to be higher in the Southwest of Yingkou Port and outside the Fudu Estuary. Cd is the principal contaminant with mild pollutant and moderate ecological risk. Cr may cause negative biological effects. The abnormal enrichment of Cu and TOC may respectively be caused by riverside industrial activities and mariculture. The abnormal enrichment of Pb in Moon Bay Beach and the Lagoon was suggested to be caused by the mooring of boats or excessive tourist activities. Grain size dominates the concentrations of heavy metals in the study area. The impact of coastal engineering on sediment quality through changing sedimentary dynamics should also be given particular attention.

Aging and Seasonal Serum Cortisol Concentrations in Captive Spotted Seals (Phoca largha) from the Liaodong Bay Colony

Aging and Seasonal Serum Cortisol Concentrations in Captive Spotted Seals (Phoca largha) from the Liaodong Bay Colony

Methodology for forecast and control of coastal harmful algal blooms by embedding a compound eutrophication index into the ecological risk index

Harmful algae bloom (HAB) is a major global ecological hazard and is a serious problem in the Bohai Sea. There have been few successful controls of HABs associated with HAB accurate predictions due to a lack of link between ecological risks and control measures. A methodology is proposed that embeds the compound eutrophication index (CEI) into an ecological risk index (ERI) for HAB prediction, which can define critical factors associated with measures of HAB control. CEI can be calculated by means of a function with 15 control elements. These are multiplied with the occurrence probability and ecosystem vulnerability to HAB events to calculate the ERI of HAB. Based on the results of CEI and ERI, it has experienced eutrophication and has been at a high-risk state since 1989 in the Bohai Sea. There is good correlation between CEI and chlorophyll a concentration, and HAB risk evaluation in accordance with ERI embedded CEI is considerable reliability in both location and time in the Bohai Sea. The ERI value averages 24% ± 35% with peak values (73% ± 4.3%) in summer, and high values (at the level of grade III of ERI, 6%) are mostly in Bohai Bay, Laizhou Bay, Liaodong Bay and the coastal sea waters of Qinhuangdao city. The contribution of terrigenous pollutant emission and concentration effects to the ERI is 63%, with reclamation and hydrodynamic effects accounting for 22%, and runoff and sediment effects accounting for 15%. Thus, actions associated with terrigenous pollutant emission/concentration would be more effective than other measures in prevention and control of HAB.

Sediment mixing of extrabasinal and intrabasinal sources in a narrow elongated half-graben? Constraints on provenance and seismic geomorphological analysis of the Upper Eocene Liaoxi Sag in the offshore northern Bohai Bay Basin (China)

The interaction of provenance systems is very complicated in narrow elongated half-graben basins, such as some small sags in the Liaodong Bay region, offshore northern Bohai Bay Basin (China). Province identification was conducted through an integrated analysis of petrographic data, heavy minerals, detrital zircon U-Pb data, and three-dimensional (3D) seismic data from the upper Eocene Liaoxi Sag, offshore Bohai Bay Basin. The (light or heavy) mineral indices together with their spatio and temporal distribution show that the Mesozoic-dominated extrabasinal source and the Neoarchaean-dominated intrabasinal source contributions to provenance mixing can be distinguished in the oilfield area. The detrital zircons sampled from the potential sediment mixing area have ages from intrabasinal and extrabasinal sources, suggesting the potential evolution of the hanging wall drainages between the syn-rift and post-rift stages. The overlapping deltaic area between the western shoal margin braided-river delta and the eastern border-fault fan deltas, providing direct visualization of provenance mixing, is well imaged, particularly during the SQ3 lowstand period, but it is not apparent from seismic geomorphological evidence throughout the entire SQ4. Further investigation also reveals that this absence may be attributed to the gradually submerged Liaoxi Low Uplift and the more frequent delta autogenic shifting due to lake-level rise. Shallower water and more efficient wave transport, however, could be another cause of sediment mixing given the presence of widely distributed lacustrine beach bars between transverse deltas from both margins during the post-rift stage. This study enhances an integrated approach to provenance analysis for distinguishing extrabasinal and intrabasinal sources as well as provenance mixing in a narrow half-graben basin on an oilfield scale, even with limited cores and cuttings for instrumental analysis in the offshore region. The study also provides further implications for reservoir properties and connectivity from different source-to-sink systems.

Grain-Size Distribution of Surface Sediments in the Bohai Sea and the Northern Yellow Sea: Sediment Supply and Hydrodynamics

The grain-size distribution of surface sediments in the Bohai Sea (BS) and the northern Yellow Sea (NYS), and its relationship with sediment supply and hydrodynamic environment were investigated based on grain-size compositions of surface sediments and modern sedimentation rates. The results showed that the surface sediments in the BS and the NYS were primarily composed of silty sand and clayey silt with a dominant size of silt. In addition, the Yellow River delivered high amount of water and sediments to the BS, and they are dominated in surface sediments (mainly silt) in the Bohai Bay, the Yellow River mouth, the center of the BS, and the north coast of Shandong Peninsula. The coarse-grained sediments were mainly deposited at the river mouth due to the estuarine filtration and physical sorting. Meanwhile, there was a significant relationship among the modern sedimentation rate, the surface sediment grain size distribution and sediment transport pattern. The areas with coarser surface sediments generally corresponded low sedimentation rates because of strong erosion; whereas the sedimentation rate was relatively high at the place that the surface sediments were fine-grained. Furthermore, the grain-size trend analysis showed that the areas with fine-grained surface sediments such as the mud area in the central BS and the upper Liaodong Bay were the convergent centers of surface sediments, except for the Bohai Bay and the subaqueous Yellow River Delta where offshore sediment transport was evident.

Analysis of Spatial and Temporal Variations of Vegetation Index in Liaodong Bay in the last 30 years based on the GEE Platform

In order to determine the space-time characteristics of vegetation growing, aiming at the problems of poor efficiency in remote sensing information extraction of traditional methods, based on the Google Earth Engine (GEE) platform, NDVI data was extracted using Landsat image in the growing season from 1990 to 2019, and the space-time characteristics of vegetation were discussed with unitary linearity regression. The results showed that, 1) Taking 2010 as the turning point, NDVI of surface vegetation in Liaodong Bay showed a trend of first increase, then decrease and then increase during the past 30 years. The total area of vegetation cover have less change, while the proportion of medium-high coverage (0.6<NDVI<0.8) and high coverage (0.8<NDVI<1) increased significantly, 2) The spatial distribution of NDVI in Liaodong Bay have obvious differences, which shows a trend of gradual decrease from the Liaohe estuary delta to both sides. Affected by the development of coastal resources, NDVI increased firstly and then decreased from land to sea. In conclusion, the space-time change of NDVI in Liaodong Bay is affected by human development activities and ecological restoration. As an important quantitative factor, NDVI can provide basic data for the evaluation of environmental carrying capacity and ecological restoration.

Synrift basin inversion: Significant role of synchronous strike-slip motion in a rift basin

Abstract In rift basins with superposed strike-slip deformation, the structural style of wrench elements and the roles they play in synrift architecture and evolution are important, poorly understood issues for basin analysis and hydrocarbon exploration. The NE-SW–striking Tan-Lu fault zone, located in eastern China, runs through the Liaodong Bay subbasin within the Cenozoic Bohai Bay Basin and experienced dextral strike-slip motion during the later synrift stage of the basin (ca. 40 Ma to 23 Ma). Investigations of the Liaodong Bay subbasin indicate that rift-fault reactivation and wrench-fault development during strike-slip reactivation were strongly controlled by the distribution and geometry of preexisting rift faults, and local synrift basin inversion, induced by strike-slip reactivation of a preexisting graben during a later synrift stage, was a significant manifestation of synchronous strike-slip motion modifying synrift architecture and evolution. Moreover, synrift basin inversion within the Liaodong Bay subbasin manifested in two ways. First, stronger inversion occurred along the restraining bends of preexisting extensional faults. This induced uplift of the footwalls of graben-controlling faults, leading to deformation characterized by abundant shortcut thrusts and folds. The Liaodong uplift formed via this mechanism, triggered by strike-slip movement along the Tan-Lu fault zone at ca. 40 Ma. Second, weaker inversion induced by newly formed, subvertical, strike-slip faults occurred near the central part of the graben, with the characteristics of positive flower structures. Although inversion was limited to a very local area along a narrow fault zone, it substantially modified the basin’s physiography. In this rift system, coincident with local inversion-induced uplift, large-scale, rift-related subsidence occurred beyond the inversion belt within the flanking graben, leading to complexity and variety in intrabasinal structural deformation and filling, and exerting a complex influence on hydrocarbon prospects. This model of synrift basin inversion has profound implications for the interpretation of inversion structures and basin dynamics in any rift basin with superposed strike-slip deformation.

Combining 3D-CNN and Squeeze-and-Excitation Networks for Remote Sensing Sea Ice Image Classification

Sea ice is one of the most prominent marine disasters in high latitudes. Remote sensing technology provides an effective means for sea ice detection. Remote sensing sea ice images contain rich spectral and spatial information. However, most traditional methods only focus on spectral information or spatial information, and do not excavate the feature of spectral and spatial simultaneously in remote sensing sea ice images classification. At the same time, the complex correlation characteristics among spectra and small sample problem in sea ice classification also limit the improvement of sea ice classification accuracy. For this issue, this paper proposes a new remote sensing sea ice image classification method based on squeeze-and-excitation (SE) network, convolutional neural network (CNN), and support vector machines (SVMs). The proposed method designs 3D-CNN deep network so as to fully exploit the spatial-spectrum features of remote sensing sea ice images and integrates SE-Block into 3D-CNN in-depth network in order to distinguish the contributions of different spectra to sea ice classification. According to the different contributions of spectral features, the weight of each spectral feature is optimized by fusing SE-Block in order to further enhance the sample quality. Finally, information-rich and representative samples are chosen by combining the idea of active learning and input into SVM classifier, and this achieves superior classification accuracy of remote sensing sea ice images with small samples. In order to verify the effectiveness of the proposed method, we conducted experiments on three different data from Baffin Bay, Bohai Bay, and Liaodong Bay. The experimental results show that compared with other classical classification methods, the proposed method comprehensively considers the correlation among spectral features and the small samples problems and deeply excavates the spatial-spectrum characteristics of sea ice and achieves better classification performance, which can be effectively applied to remote sensing sea ice image classification.

A Study on the Cause of Layered Seawater Intrusion in the Daqing River Estuary of Liaodong Bay, China

Groundwater over-pumping in estuary cities leads to a series of groundwater environmental problems that seriously restricts economic development. On the basis of field investigation and long-term monitoring data analysis, a three-dimensional numerical model was built in the estuary of the Daqing River in Liaodong Bay, China. The Quaternary overburden can be generalized into five layers according to particle composition and parameters in the vertical direction. There are many scattered irrigation wells pumping in the second layer, and three water source areas mainly pumping groundwater in the fourth layer. Long-term over-pumping in multi-layered aquifers causes onshore layered seawater intrusion. The laws of layered intrusion under the layered pumping were calculated and analyzed with SEAWAT-2000, and the sensitivity was analyzed with the Sobol method. Results showed that the intrusion area had an obvious layered law. Layered pumping directly affected the layered intrusion area, as different permeability, tide and barrage further affected it. The prediction study showed that the cone of depression recovered after the pumping-limit of water source areas, and the intrusion area started to retreat in the fourth layer. At that time, the pumping quantity of irrigation wells became the main reason for the increase of the intrusion area. If the water source areas are used to bear part of the irrigation demand, so as to reduce the pressure of pumping in the second layer, the overall intrusion area can be reduced by about 0.23 km2 under the same pumping quantity.

Benthic foraminifera and its response to heavy metal pollution: A case study from Liaodong Bay, China

Benthic foraminifera can be used as an environmental bioindicator, especially in the polluted environment where their sensitivity to pollutants may be expressed by a modification in the assemblage. Based on the quantitative and qualitative analysis of 189 surface sediment samples in Liaodong Bay, 76 benthic foraminifera species which belong to 40 genera were recognized. Q-mode factor analysis was made for the 32 benthic foraminifera species, and three assemblages are recognized: Ammonia aomoriensis- Cribroelphidium magellanicum- Protelphidium tuberculatum; Textularia foliacea- Polskiammina asiatica; and Rotalidium annectens- Buccella frigida. To study the effects of heavy metal elements on benthic foraminifera fauna, seven heavy metals elements have been analyzed in all the surface sediment samples, the results show that the heavy metal elements in Liaodong Bay are mainly distributed in Jinzhou Port, and that the overall characteristics are high in northwest and low in southeast. The distribution of foraminifera and heavy metals elements reveals that there is a significant correlation between them. Cribroelphidium magellanicum and Protelphidium tuberculatum have maintained a high level in heavy metal enrichment areas, and may be used as an indicator of heavy metal contamination along the coast of Liaodong Bay.