Wind impact on pollutant transport in a shallow estuary

A three-dimensional numerical model, EFDC （ environmental fluid dynamics code） is applied to the Pamlico River Estuary （PRE） in eastern North Carolina of the United States to examine the wind impact on pollutant age distributions and residence time. A series of model experiments representing base case, remote-wind-induced water level set-up and local winds cases are conducted. Model results indicate that the pollutant mean age and the system residence time are functions of gravitational circulation in the PRE. The system responses to remote-wind-induced water level set-up are different in different portions of the PRE. Under such condition, dissolved substances in the upstream portion of the PRE have a younger age and shorter residence time （compared with the base case） , by contrast, they have a older age and longer residence time in the downstream portion of the PRE. Upriver and downriver local winds appear to have opposite impacts on pollutant age distributions. The substances are retained much longer within the PRE under upriver wind than those under downriver wind. The model results also suggest that across - river winds may lead to longer residence time through enhanced turbulence mixing, which slows down the gravitational circulation in the PRE.     

地下卤水中镭的富集与测定方法研究

以自配人工卤水,采用硫酸钡（镭）共沉淀法富集其中的镭,同时用γ谱仪同步测量^226Ra和^228Ra的含量。不同pH和共沉淀剂作用下的化学及放化回收率计算表明,该方法操作简单,回收率高,适用于地下卤水及其它水体较高含量^226Ra、^228Ra的同步测定。用该方法测定的莱州湾地下卤水^226Ra和^228Ra含量分别为0．341Bq／L和1．615Bq／L,远高于海水中镭的含量。     

Assessing the extent of mangrove change caused by Cyclone Vance in the eastern Exmouth Gulf, northwestern Australia

Changes in mangal area were quantified in the eastern Exmouth Gulf over six years (1999–2004) after Cyclone Vance using Landsat TM satellite imagery and aerial photography. Vance was the strongest tropical cyclone ever to impact the Australian mainland before 2006 and produced wind gusts of more than 280 km h⁻¹. Image data were processed using ENVI™ and IDRISI™ software. Three sets of Landsat TM images from 1999 (a few days before the cyclone), 2002 and 2004 were used, along with 2004 digital aerial photography. A ‘common’ subset of 904 km² was selected from all images and classification was developed using ISODATA™ unsupervised classification to identify spectrally distinct areas followed by principal component analysis (PCA), vegetation indices and supervised classification. Some 12,800 ha of mangrove habitat was present before the cyclone and approximately 5700 ha (44%) was removed by it. Most mangroves lost (74%) between 1999 and 2004 were converted either to bare sediment or to live saltmarshes and this occurred mostly between 1999 and 2002. Five basic categories of damage were conspicuous from imagery and field observations, and evidence suggests that much of the loss was due to the longer term consequences of sediment deposition or smothering, rather than the immediate effects of wind or waves. Mangroves exhibited accelerated recovery between 2002 and 2004, and around 1580 ha regenerated during this time, amounting to a return of 68% of their former coverage. At this recovery rate we estimate that they should have returned to their pre-cyclone area by 2009. Over half of the saltmarsh habitats (54%) were removed by the cyclone (4060 ha) but their recovery has been far more rapid than mangroves. After 5 years, saltmarshes had returned to 87% of their previous area. The 5700 ha of mangrove habitat damaged by Cyclone Vance exceeds any anthropogenic impact that has ever taken place in Western Australia by several orders of magnitude.     

基于分光光度法的多量程海水营养盐原位传感器检测系统设计

针对传统海水营养盐检测方法不能满足海水营养盐长期原位监测需求的问题,研制了一种基于分光光度法的多量程海水营养盐原位传感器检测系统,通过对系统的高度集成及对多量程检测、低功耗技术、漏液保护技术的应用,实现了对海水5项营养盐参数快速、宽范围、高精度的原位测量。经过实验室和青岛中苑码头现场测试,表明本营养盐传感器检测系统具有低功耗、高可靠性能,可满足对5项营养盐参数的快速精确测量要求,实现了对海水营养盐参数的原位监测,为相关部门及时了解海洋生态环境和水体富营养化程度提供了数据支持,具有重大现实意义。     

Spatio-temporal variability of small fishes related with environmental factors in a typical domestic tap water lake,Eastern China

The knowledge of prey small ?sh stock, distribution and abundance is necessary to guide stocking of piscivorous ?sh for the biomanipulation in domestic tap water lakes. This study describes the current status of small ?sh community in Kuilei Lake(China), and examines the spatial and seasonal variations of the community in relation to key environmental factors. Based on submerged macrophyte cover and water depth, the lake was divided into ?ve major habitats:(1) macrophyte covered shallow habitat of water depth< 2.00 m,(2) uncovered or less-covered shallow habitat(2.00 m–3.50 m),(3) uncovered medium shallow habitat(3.50 m–5.00 m),(4) uncovered medium deep habitat(5.00 m–6.50 m) and(5) uncovered deep habitat(6.50 m–8.50 m). The abundance and composition of small ?sh were monitored by benthic fykenet sampling from April 2013 to January 2014. A total of 2881 individuals belonging to 5 families and 21 species were collected. Based on their abundance(accounted for 88.96% of the total) and occurrence(more than 33.33%), Acheilognathus chankaensis, Acheilognathus macropterus, Microphysogobio microstomus,Pseudorasbora parva and Rhinogobius giurinus were recognized as dominant small ?sh species. The results of correlation analysis identi?ed that species richness( Sr), Shannon-Wiener diversity index( H′)and Margalef′s richness index( D) were signi?cantly negatively correlated with water depth, but positively correlated with biomass of submerged macrophytes.Redundancy analysis(RDA) revealed that the spatial distributions of most small ?shes were negatively associated with water depth. The details of these ?ndings are bene?cial to understanding the adaptation of the small ?shes in degraded environments, and to developing suitable biomanipulation strategies for the management of ?sh resources and water quality in the lakes along the lower reach of the Changjiang(Yangtze) River basin.     

Network analysis to inform invasive species spread among lakes

Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.     

Network analysis to inform invasive species spread among lakes

Often facilitated by human-mediated pathways,aquatic invasive species are a threat to the health and biodiversity of global ecosystems.We present a novel approach incorporating survey data of watercraft movement in a social network analysis to reconstruct potential pathways of aquatic invasive species spread between lakes.As an example,we use the green alga Nitellopsis obtusa,also known as starry stonewort,an aquatic invasive species affecting the Great Lakes region in the United States and Canada.The movement of algal fragments via human-mediated pathways(i.e.,watercraft)has been hypothesized as the primary driver of starry stonewort invasion.We used survey data collected at boat ramps during the 2013 and 2014 openwater seasons to describe the flow of watercraft from Lake Koronis,where N.obtusa was first detected in Minnesota,to other lakes in the state.Our results suggest that the risk of N.obtusa expansion is not highly constrained by geographic proximity and management efforts should consider highly connected lakes.Estimating human movement via network analysis may help to explain past and future routes of aquatic invasive species infestation between lakes and can improve evidence-based prevention and control efforts.     

Nutrients and zooplankton composition and dynamics in relation to the hydrological pattern in a confined Mediterranean salt marsh (NE Iberian Peninsula)

The role of the hydrological regime in the nutrients and zooplankton composition and dynamics has been analysed in five lagoons of La Pletera salt marshes (NE Iberian Peninsula) during a complete hydrological cycle (2002–2003). Two of the lagoons have their origin in the old river mouths while the other three were recently created in the framework of a Life Restoration project. This fact has also allowed us to study the effect of the lagoon age on nutrient and zooplankton composition and dynamics. The salt marsh hydrology is determined by a prolonged period of confinement without water inputs, irregularly interrupted by sudden water inputs due to flooding events (sea storms or intense rainfalls). While the dynamics of oxidized nitrogen compounds in the lagoons depends on the water inputs variability within each hydrological cycle, the internal load of phosphorus, total nitrogen and organic matter is related more to the cumulative mechanisms during the confinement periods. Accumulation processes may be easily related to lagoon age, since old lagoons have higher content of nutrients and organic matter, suggesting that these lagoons progressively accumulate nutrients during the successive confinement events. This is the usual case for most Mediterranean salt marshes without an artificially manipulated water regime. The zooplankton community in La Pletera integrates the effects of both the hydrological regime and the lagoon age since the former determines the temporal pattern of the main zooplankton species and the latter explains differences in composition and structure between old and new lagoons.     

Effects of crab–halophytic plant interactions on creek growth in a S.W. Atlantic salt marsh: A Cellular Automata model

The Bahía Blanca Estuary (38° 50′ S, and 62° 30′ W) presents salt marshes where interactions between the local flora (Sarcocornia perennis) and fauna (Chasmagnathus granulatus) generate some kind of salt pans that alter the normal water circulation and condition its flow and course towards tidal creeks. The crab–vegetation dynamics in the salt marsh presents variations that cannot be quantified in a reasonable period of time. The interaction between S. perennis plant and C. granulatus crab is based on simple laws, but its result is a complex biological mechanism that causes an erosive process on the salt marsh and favors the formation of tidal creeks. To study it, a Cellular Automata model is proposed, based on the laws deduced from the observation of these phenomena in the field, and then verified with measurable data within macroscale time units. Therefore, the objective of this article is to model how the interaction between C. granulatus and S. perennis modifies the landscape of the salt marsh and influences the path of tidal creeks. The model copies the basic laws that rule the problem based on purely biological factors.The Cellular Automata model proved capable of reproducing the effects of the interaction between plants and crabs in the salt marsh. A study of the water drainage of the basins showed that this interaction does indeed modify the development of tidal creeks. Model dynamics would likewise follow different laws, which would provide a different formula for the probability of patch dilation. The patch shape can be obtained changing the pattern that dilates.     

Analysis, synthesis and modelling of high-resolution observations of salt-marsh eco-geomorphological patterns in the Venice lagoon

The present paper describes observations, analyses and models of salt-marsh channel network and vegetation patterns with the aim of contributing to the development of predictive models of ecological and morphological co-evolution. Existing and new observations are described, with particular emphasis on remote sensing and ancillary field surveys, which are shown to allow reliable, accurate and repeatable quantitative characterizations of landform and vegetation properties over the spatial scales of interest. The observed channel network morphological characters are then used as the basis and validation of models describing the emergence of channel network and vegetation spatial patterns. In particular, with reference to observations performed in the Venice Lagoon, the note describes: (i) new, 2-cm resolution, characterizations of channel network geometry obtained from “proximal sensing” photographic observations; (ii) the reliable quantitative maps of salt-marsh vegetation which may be retrieved from hyperspectral remote sensing data and field ancillary observations; (iii) a synthesis of recent and new analyses of the statistical properties of vegetation and landform spatial organization, that may be inferred from the maps so derived; (iv) recent and new conceptual and quantitative ecological and geomorphic models developed and validated by remote-sensing and field observations. A coherent observational and theoretical eco-morphodynamic framework is then proposed.