Southern Lake Research Articles

Spatial Distribution of Aerobic Bacteria, Sources and Risks of Nitrogen and Phosphorus in Taihu Lake Sediments

The release of nitrogen and phosphorus from sediments into lake water will exacerbate the eutrophication of lakes and endanger ecological safety and human health. Microorganisms are indispensable in nitrogen and phosphorus conversion, and accurate analysis of the distribution characteristics and sources of nitrogen and phosphorus in sediments as well as their relationship with microorganisms is an important prerequisite for lake eutrophication control. Taking Taihu Lake as the study area, 30 surface sediment samples were collected, and the grain size, pH, organic matter (OM), dissolved organic carbon (DOC), total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (NO3--N), and dissolved organic nitrogen (DON) along with some other index contents were measured and analyzed; accordingly, spatial distribution characteristics were analyzed. While using nutrient agar (NA), the number of aerobic bacteria (AB) was determined by plate counting in the medium. Combined with principal component analysis (PCA) and Pearson correlation analysis, the spatial distribution characteristics and sources of sediments and AB in Taihu Lake were explored. The characteristics of sediment pollution in Taihu Lake were studied using the comprehensive pollution index and the organic pollution index methods. The results revealed that the average sediment indicators of the surface layer of Taihu Lake were as follows:AB was 9.25×104 CFU·g-1, average particle size (MZ) was 17.59 μm, pH was 7.62, ω(OM) was 15.05 g·kg-1, ω(DOC) was 71.60 mg·kg-1, ω(TP) was 598.13 mg·kg-1, ω(TN) was 1113.92 mg·kg-1, ω(NO3--N) was 3.22 mg·kg-1, and ω(DON) was 22.60 mg·kg-1. The comprehensive pollution index (FF) showed that 13% of the Taihu Lake was moderately polluted, while 87% was heavily polluted. Excluding the area in the center of the lake, the southern lake area, and some lakes in the western part of the East Taihu Lake, TN in the rest of the area was moderately and severely polluted. In addition to the heavy pollution of Zhushan Bay, the TP in Taihu Lake was generally at light and moderate pollution. The organic pollution index (OI) showed that the organic pollution of the sediments of Taihu Lake was relatively light, majorly caused by organic nitrogen (ON) pollution. DOC, DON, TN, and OM in Taihu Lake were primarily derived from the influence of aquatic plants, and TP And AB were primarily derived from the influence of the external input of rivers. This research will provide theoretical support for lake eutrophication treatment and also provide new ideas for further analysis of AB to remove nitrogen and phosphorus pollution from sediments.

Archaeobotanical Insights into Kañawa (Chenopodium pallidicaule Aellen) Domestication: A Rustic Seed Crop of the Andean Altiplano

Kañawa/Cañihua (Chenopodium pallidicaule Aellen) is the lesser-known cousin of the domesticated Andean pseudocereal quinoa (Chenopodium quinoa Willd.). In 1970, Daniel Gade hypothesized that Andean farmers may have domesticated volunteer wild kañawa plants that occupied quinoa or potato fields after observing that they could survive harsh climatic events such as drought or frost. To revisit this question of kañawa domestication, this paper provides an overview of the current botanical, genetic, and archaeological knowledge of kañawa domestication. It then provides patterns in the presence of wild and domesticated kañawa seeds from archaeological sites in the southern Lake Titicaca Basin of Bolivia, spanning the Formative and Tiwanaku periods from approximately 1500 BCE to 1100 CE. This archaeobotanical evidence supports Gade’s hypothesis that kañawa was a later domesticate, not appearing until after 250 CE. Regional paleoclimatic evidence of frequent climatic fluctuations lends support to the argument that kañawa contributed to a diversified food supply, which could provide a buffer against climate risks.

Estimates of adult Lake Trout mortality fromcoded wiretags in a population with developing natural reproduction in southern Lake Michigan

AbstractObjectiveOverfishing and Sea LampreyPetromyzon marinuspredation led to extirpation of Lake TroutSalvelinus namaycushfrom Lake Michigan in the 1950s. Large populations of hatchery‐reared fish were developed by the 1970s, but natural reproduction was limited until the early 2000s when it began to increase in the southern main basin. Hypothesizing that the relatively low mortality of spawning‐aged fish contributed to this reproductive success, we estimated the total annual mortality rate for this population.MethodsWe used catch curves to estimate the total instantaneous mortality rateZusing coded wire tags, which provided definitive ages. We made separate estimates from fish collected in three on‐going surveys: a spring gill‐net survey, a fall gill‐net spawning survey, and a sport fishery survey.ResultOur estimates ofZ ± SE were 0.297 ± 0.019, 0.239 ± 0.009, and 0.205 ± 0.007 for the spring, spawning, and sport fishery surveys, respectively. We suggest that the meanZ ± SE of all survey estimates of 0.247 ± 0.027 would be a reasonable estimate for this population, which equates to a total annual mortality of 22 ± 3%. This estimate is in the low range of rates reported for the species and is in the same range as other populations in the Great Lakes with well‐established natural reproduction.ConclusionWe concluded that these low total mortality rates contributed to the reproductive success in southern Lake Michigan through increasing spawning stock density and age structure and that previous estimates of another important population parameter, the instantaneous natural mortality rateM, were too high. Estimates ofMranged from 0.210 to 0.240 and were based on the Pauly equation, a growth‐ and temperature‐based estimator. We suggest maximum‐age‐based estimators ofMare more appropriate for Lake Trout. Several alternative maximum‐age‐based estimators produced estimates forMof 0.132–0.058, all of which are more compatible with our estimate ofZ.

Genetic diversity and population structure of Vernonia amygdalina Del. in Uganda based on genome wide markers.

Determining the extent and distribution of genetic diversity is an essential component of plant breeding. In the present study, we explored the genetic diversity and population structure of Vernonia amygdalina, a fodder, vegetable and medicinal species of Africa and some parts of Yemen. Most empirical studies demonstrate that populations that are separated by geographic or ecological factors may experience genetic differentiation resulting from restricted gene flow between populations. A total of 238 individuals were sampled from two populations: i) Lake Victoria crescent (LVC) and ii) Southern and Eastern Lake Kyoga basin (SEK) agroecological zones of Uganda and genotyped using DArT platform. Of the two populations, the overall mean observed heterozygosity (Ho) was low to medium (Ho = 0.07[silicoDArTs] and 0.2[SNPs]). Inbreeding levels were also very low (-0.04 to -0.08) suggesting the presence of random mating. Partitioning of genetic structure in the two populations indicated that SEK exhibited a higher genetic diversity than LVC. The principal coordinates analysis (PCA) showed no geographical structuring, consistent with the low genetic differentiation (Fst = 0.00) and the low Euclidean genetic distance (1.38-1.39) between the LVC and SEK populations. However, STRUCTURE analysis with admixture models revealed weak possible genetic clusters with very small genetic distance among them. Overall, the results suggest low genetic diversity and weak genetic differentiation between the two populations. One possible explanation of the results could be the presence of human assisted gene flow over long distances.

A Quantification of Heat Storage Change-Based Evaporation Behavior in Middle–Large-Sized Lakes in the Inland of the Tibetan Plateau and Their Temporal and Spatial Variations

A large number of different-sized lakes exist in the inland area of the Tibetan Plateau (TP), which are examples of the important connection between the atmosphere and hydrosphere through the analysis of lake surface convergence and evaporation processes. The evaporation level changes that occur in middle–large-sized lakes (surface area > 50 km2) in the area directly influence the regional mass and energy balance values, atmospheric boundary layer heat and humidity structures, and weather processes occurring in the lower-reach areas. The studies conducted in the literature at present, concerning lake evaporation processes, generally overlook the differences in lake heat storage behavior due to the reduced amount of data in the literature concerning lake bathymetry. According to the in situ bathymetric data obtained for 68 middle–large-sized lakes in the inner basin of the TP, in this study, we calculated their heat storage (G) change values by using the different vertical-depth water-temperature-change integral method, and we established a regression equation for the heat storage and lake surface net radiation values for 68 lakes. The evaporation rates of 134 middle–large-sized lakes larger than 50 km2 in the inland are of the TP were calculated by obtaining the G regression result and adopting it into the Penman model, as well as estimating the evaporation losses of theses 134 lakes from 2002 to 2018. The result shows that the annual average evaporation rate for these lakes is 927.39 mm/year, with an insignificant upward trend (0.10 mm/year). This method achieved good accuracy compared with the Bowen ratio method, which estimates the evaporation rate during the ice-free season, with a high correlation coefficient (R) value of 0.95 and least root mean square error (RMSE) value of 61 mm. The annual mean evaporation rate can be divided into the southern and northern lake groups along a 34°N line with a difference of 314.41 mm/year. The annual average evaporation volume of these lakes was 25.02 km3 and showed an upward trend of 0.35 km3/year. Among them, the annual average evaporation volume contribution ratio of level-1 lakes (50 km2 ≤ lake’s area < 100 km2, 61 lakes) was 14.04%, showing an upward trend, and the contribution of level-3 lakes (lake’s area ≥ 500 km2, 10 lakes) was 41.50%, showing a downward trend. There were no obvious changes in the level-2 lakes (100 km2 ≤ lake’s area < 500 km2, 63 lakes), which maintained at the same level in approximately 44.46%. Air temperature is the most important factor affecting the evaporation rate of lakes, while the lake surface area is the main factor affecting lake evaporation volume. Our study, considering the actual lake heat storage value, provides a useful reference for further improving lake water budget balance values and watershed hydrologic features in the inland closed lakes located in the TP.

The Impact of Charcoal Iron Production on the Landscape of the South Lakes, Cumbria (UK) During the Eighteenth Century Using Archival Material Combined with Remote Mapping Techniques

ABSTRACT The history of the charcoal iron trade in the Southern Lake District in Cumbria, England is well recognised, with activity controlled by a very small number of iron production companies intensifying during the eighteenth century. This activity, from the initial extraction of the ore, through the development of a transport infrastructure and the construction of furnaces, to the management of woodlands for charcoal production, has left its mark on the landscape. A wealth of untapped information is held in the region’s documentary archives, which provides data on the iron production companies themselves, primarily via account books and associated documents. These records include detail on the charcoal bought in—not only the dates and precise quantities, but the names of the source woodlands and even the names of the individual producers themselves. Using GIS, these sources have been examined in combination with remotely sensed data to provide new evidence of the impact of the iron trade on the woodlands of the Lake District. The results demonstrate that charcoal production was so vital to the iron industry that the woodlands were carefully and sustainably managed, the legacy of which we enjoy today.

Reassessment of the declines in the largest freshwater lake in China (Poyang Lake): uneven trends, risks and underlying causes

Water level decline in the largest freshwater lake in China (Poyang Lake) has raised grave concerns and continuous debates regarding the proposal of a water control project. Previous hydrologic investigations on the water level decline in Poyang Lake were conducted mostly during recession season and typical dry years and hence lacked the comprehensive view of associated risks and possible spatial heterogeneity of trend during low water level periods. The present study reassessed the long-term trend and regime shift of low water level variations and their associated risks based on hydrological data across multiple stations in Poyang Lake during 1952–2021. The underlying causes of the trends of water level decline were further investigated. Results showed uneven trends and risks of water level variations in different seasons and across different lake regions. The water level of all five hydrological stations in Poyang Lake significantly dropped in the recession season, and the risks of water level decline evidently increased since 2003, which could be largely attributed to the water level drop in the Yangtze River. In terms of the dry season, clear spatial differences of long-term trend of water level were found, with water level in the central and southern lake regions significantly dropping, which was probably caused by dramatic bathymetry undercutting in the central and northern lake regions. In addition, the impacts of topographic changes became significant when water level of Hukou fell below 13.8 and 11.8m for the northern and southern lake regions, respectively. By contrast, water level in the northern lake region showed increasing trends in the dry season. In addition, only the occurrence time of water level under moderate risk significantly advanced for all stations except for Hukou. The present study could provide a full picture of low water level trends, associated risks across different lake regions and underlying causes in Poyang Lake, thus providing insights into adaptive water resources management.

Study on Water Replacement Characteristics of Xinghai Lake Wetland Based on Landscape Water Quality Objectives

Many issues with water quality and water ecology are caused by the Xinghai Lake’s enormous catchment, significant evaporation rates, and one additional water supply. To quantitatively study Xinghai Lake’s water displacement characteristics, a two-dimensional hydrodynamic-tracer coupling model based on MIKE21 was developed. The findings indicate that: (1) Xinghai Lake’s water replacement cycle exhibits spatial heterogeneity, with a general characteristic of fast water renewal in the southern lake area and slow renewal in the northern lake area, and the gradient change of the water replacement cycle from south to north is influenced by a variety of factors, including the lake’s flow field, flow, topography, and wind field. (2) The throughput flow has an impact on the majority of the waters in Xinghai Lake. When there is a high water flow, the lake region has a high flow velocity, rapid water transport, and a large capacity for water exchange; when there is a low water flow, the lake area has a slow flow velocity, poor water flow, and a lengthy water exchange period. (3) The flow field of Xinghai Lake is complicated, the flow velocity is low, and it is a lake system where quick water exchange and slow water exchange coexist. This flow field is influenced by the interplay of wind-generated flow and throughput flow. (4) To speed up the water body’s rejuvenation, the Xinghai Lake wetland needs more inlets and exits to introduce new water sources.

Simulation of Neighborhood‐Scale Air Quality With Two‐Way Coupled WRF‐CMAQ Over Southern Lake Michigan‐Chicago Region

AbstractThe southern Lake Michigan region of the United States, home to Chicago, Milwaukee, and other densely populated Midwestern cities, frequently experiences high pollutant episodes with unevenly distributed exposure and health burdens. Using the two‐way coupled Weather Research Forecast and Community Multiscale Air Quality Model (WRF‐CMAQ), we investigate criteria pollutants over a southern Lake Michigan domain using 1.3 and 4 km resolution hindcast simulations. We assess WRF‐CMAQ's performance using data from the National Climatic Data Center and Environmental Protection Agency Air Quality System. Our 1.3 km simulation slightly improves on the 4 km simulation's meteorological and chemical performance while also resolving key details in areas of high exposure and impact, that is, urban environments. At 1.3 km, we find that most air quality‐relevant meteorological components of WRF‐CMAQ perform at or above community benchmarks. WRF‐CMAQ's chemical performance also largely meets community standards, with substantial nuance depending on the performance metric and component assessed. For example, hourly simulated NO2 and O3 are highly correlated with observations (r > 0.6) while PM2.5 is less so (r = 0.4). Similarly, hourly simulated NO2 and PM2.5 have low biases (<10%), whereas O3 biases are larger (>30%). Simulated spatial pollutant patterns show distinct urban‐rural footprints, with urban NO2 and PM2.5 20%–60% higher than rural, and urban O3 6% lower. We use our 1.3 km simulations to resolve high‐pollution areas within individual urban neighborhoods and characterize seasonal changes in O3 regimes across tight spatial gradients. Our findings demonstrate both the benefits and limitations of high‐resolution simulations, particularly over urban settings.

Composition and spore abundance of arbuscular mycorrhizal fungi in sweet potato producing areas in Uganda

IntroductionFarming systems influence composition and abundance of microbial communities.MethodologyA study was conducted using morphotyping and enumeration methods to determine the composition and spore abundance of Arbuscular Mycorrhizal Fungi (AMF) in sweet potato producing regions in eastern Uganda. Sampling was done from fields with crop types (CTs) including legumes (groundnuts, common beans, cowpea, soybeans, green grams), sorghum, sweet potato, and fallowed fields which were used as a control. Three agro-ecological zones (AEZs) i.e., Mt. Elgon High Farmlands (MEHF), Lake Victoria Crescent (LVC), and Southern and Eastern Lake Kyoga Basin (SELKB) were considered.Results and discussionA total of 6 AMF genera comprising of Glomus, Acaulospora, Scutellospora, Entrophospora, Archaeospora, and Gigaspora were isolated from the study sites. Agro-ecological zones had a significant (p<0.05) effect on Entrophospora spp. while crop types had a significant (p<0.05) effect on Gigaspora spp. although all the AMF genera were present in all AEZs and CTs. Spore abundance was similar across the AEZs except for MEHF (177) which was lower while spore abundance lowest in sweet potato (177) and largest in fallow (224), attributed to soil properties and similar crops included in the crop rotation program. The AMF can be isolated, identified, and multiplied to produce bioinoculants for the regions.

Key factors driving dissolved organic matter composition and bioavailability in lakes situated along the Eastern Route of the South-to-North Water Diversion Project, China

The Eastern Route of the South-to-North Water Diversion Project (SNWDP-ER) is a large scale multi-decade infrastructure project aiming to divert substantial amounts of water (≈45 billion m3 yr−1) to alleviate water shortage in comparatively arid regions of northern China. The project has ramifications for hydrological connectivity and biogeochemical cycling of dissolved organic matter (DOM) in regional lakes affected by the project. We carried out an extensive field sampling campaign along the SNWDP-ER in different hydrological seasons of 2018 and monthly observations in Lake Hongze and Lake Luoma from April 2018 to June 2021. We found the lakes connecting to the SNWDP-ER had higher mean DOC, specific UV absorbance, higher ratio of humic-like to protein-like fluorophores (Humic : Protein), and shallower spectral slope (S275–295) in the wet season compared to the wet-to-dry transition, and dry seasons. The southern lakes and Yangtze River had lower DOC concentration, bioavailable DOC (BDOC), and higher DOM aromaticity compared to the northern two downstream lakes. Ultrahigh-resolution mass spectrometry (FT-ICR MS) revealed higher relative abundance of CHO-containing and aromatic compounds in the Yangtze River and the southern three upstream lakes compared to the northern two lakes. The data from Lake Hongze and Lake Luoma, studied in different hydrological seasons, suggest that water delivery had high consistency in DOM composition and BDOC over the season. We conclude that positioning along the watercourse and seasonally variable hydrological conditions play an important role in influencing the DOM composition and bioavailability of key lakes connecting to the SNWDP-ER. Our results indicated that the water diversion project delivers water with low DOC concentration and higher aromaticity and thus is of higher quality since it has higher DOM removal potential during drinking water treatment.

A Bayesian network model for bluff retreat on the southern Lake Erie coast, United States

Coastal bluffs on the 73 km Pennsylvania mainland coast of Lake Erie consist of unconsolidated glacial through paleo-lacustrine Quaternary strata overlying Devonian shale bedrock. Erosion is a significant environmental hazard on this coast where the long-term average annual retreat rate at the bluff crest is ∼ 0.15 m/yr. As the primary geomorphic feature used to track land loss on high-relief coasts, understanding the processes that drive bluff-crest retreat and concomitant sediment and infrastructure losses remains a challenge in coastal-hazard management. This paper shows that bluff retreat on the Lake Erie coast of Pennsylvania can be successfully modeled using multivariate statistics that may have application to bluff settings across the Great Lakes basin and globally. A Bayesian Network (BN) model is developed using long-term historical data (1938–2007 training datasets) and validated against subsequent crest retreat mapped from recent lidar data. Seven field sites were sampled for environmental data that collectively covered ∼ 30 % of the 33.5 km length of the western Erie County littoral cell (WECLC). A BN with eight inputs correctly predicted bluff retreat rates for 95.4 % of transects and had a mean posterior predictive probability of 84.1 %. Scenarios show that greater crest-retreat rates were more likely to be associated with greater wave impact hours, less-resistant stratigraphy, narrower beaches, lower and steeper bluffs, a more energetic run-up regime, and a lower or absent bedrock-toe ledge. These diagnostic attributes should be useful across the WECLC to help identify, with finer spatial resolution, sectors with higher probabilities of having or developing significant erosion problems.

New radiocarbon dates and the prehistoric human occupation at the Lake Qinghai Basin, northeast Tibetan Plateau

The Tibetan Plateau is known as the rooftop of the planet. Its hypoxic atmosphere in low oxygen partial pressure, extreme seasonal climate variation, and aridity poses severe challenges as harsh living environments for prehistoric human to occupy in such high-altitude niches. However, the Lake Qinghai is the largest lake on the Tibetan Plateau and the basin has rich water, mineral, and wild food resources, and prehistoric human occupied the Lake Qinghai Basin long before local farming was in practice. In this paper we present results of faunal assemblages associated with variable stone artifacts and pottery shards with bone collagen accelerator mass spectrometry radiocarbon (AMS 14C) dates from 3 new archaeological sites to investigate human occupation history in the southern Lake Qinghai Basin. The AMS 14C dating results reveal that the occupation occurs intermittently from the late Glacial to entire Holocene. Through compilation and synthesis of regional archaeological records, we found that prehistoric humans went through 3 phases of subsistence strategies: 1) hunting large and medium ungulates; 2) hunting medium ungulates; 3) foraging small size mammals with birds and fish diets. At the end, prehistoric humans increasingly adapted to forage and consume caprinaes species (goat), which represents a precursor of domestication or semi-domestication of wild animals in the Lake Qinghai Basin. We further attribute the utilization of caprinaes animal resources to the lower limbs of toe and phalange bones with low nutritious values to advanced social organization that implied prehistoric humans separated hunting activity from protein processing practices. Our investigation of zooarchaeology with reliable bone collagen AMS 14C dates could become a novel approach to study adaptation strategy and social structure changes of prehistorical Tibetan humans.

Optimal operation toward energy efficiency of the long-distance water transfer project

Energy efficiency plays an important role in the sustainable operation of the world's largest water transfer project, i.e., China’s South-to-North Water Transfer Project, by reducing its energy-related operating costs. However, effective energy-saving measures are still under development for the project due to its huge scale and complexity. An optimized operational model was established in this study to reduce the energy use of the eastern route of the South-to-North Water Transfer Project by optimally scheduling the water-pumping process of the different pumps along the transfer route in the context of hydrological variability. The optimized operational rules and recommended operational parameters were obtained. The results show that the proposed operational rules in the form of piecewise functions can reduce the water pumping of the project, thus providing a basis for reducing energy consumption. The energy use of the project’s water pumping could also be reduced in the wet years by using the local water in midstream lakes along the transfer route rather than the pumped water from the Yangtze River at the southern terminus of the route. In addition, it was also found that the initial water storage of the lakes along the southern part of the route has a greater impact on the volume of the water pumping. Raising the water levels of these southern lakes using local runoff at the beginning of a year would help reduce the subsequent water pumping from the Yangtze River and the relative energy use of the project. In addition. the key areas for energy-saving along the eastern route of the South–North Water Transfer Project were identified, providing new insights for understanding the water-energy nexus behaviors of a long-distance water transfer project.

Результаты первой попытки привлечения пары орлана-белохвоста в искусственное гнездовье

Результаты первой попытки привлечения пары орлана-белохвоста в искусственное гнездовье

Lake dynamics in an Early Jurassic desert: Evidence from the Clarens Formation in southern Africa

ABSTRACTInterdune deposits are sensitive to climatic fluctuations and ancient interdune lacustrine systems can reveal the drivers of erg dynamics through time and space. This southern African study details the dynamics of interdune deposition in a vast ancient desert system that was active over Pangaea in the Middle Mesozoic and formed part of one of the largest known sand seas in Earth's history. Focusing on the Sinemurian to Pliensbachian Clarens Formation in the main Karoo Basin (south‐west Gondwana), three facies associations were identified that formed in meso‐scale and macro‐scale lakes amongst aeolian dunes and sand sheets of the Clarens erg system. The northern facies association is restricted to interdune hollows within an actively climbing dune system. High‐sediment availability and high‐wind speeds limited the space available for these meso‐scale lakes to expand. Here, migrating dunes outpaced the water table rise promoting the formation of discontinuous lenses of lake deposits, as is typical in erg centres. The southern facies associations developed both in spatially isolated meso‐scale lakes, where flooding was controlled by groundwater inundation (water table rise), as well as in macro‐scale lakes, where flooding was related to groundwater inundation and floods (surface runoff) that induced terminal splays. Relative to the north, the southern facies associations, with their more significant thickness and lateral extent, show that, here, the basin was characterized by a higher rate of relative subsidence. Moreover, the southern lake systems were established along the erg's margin, where the interdunes expanded during pluvial phases. Ultimately, the facies associations in the Clarens Formation show that the widespread arid conditions in the Early Jurassic of south‐west Gondwana were subjected to prolonged and repeated pluvial phases in an otherwise harsh environment. Given the prominence of Jurassic aeolianites across Pangea, this study provides a southern African perspective on global palaeo‐erg dynamics and Early Jurassic climatic shifts.

River–Lake System Connectivity Effectively Reduced the Salinity of Lake Water in Bosten Lake, Northwest China

High salinity in water constitutes a serious problem for the aquatic environment management of Bosten Lake. Weak water exchange and water movement are the essential factors for the high total dissolved solids (TDS) content of lake water. To improve the water quality of Bosten Lake, a river–lake system connectivity project (water diversion) was introduced starting at the end of 2018, which diverted fresh water from the Kaidu River and the Huangshuigou River to Bosten Lake. In this study, the effect and its mechanism of water diversion on the TDS content of Bosten Lake were evaluated using continuous-field monitoring data. The results showed that the water diversion effectively reduced the TDS content of the lake water and changed Bosten Lake from a brackish lake back to a freshwater lake. Water diversion also improved the spatial distribution of TDS content. One year, two years, and three years after the implementation of the water diversion project, the TDS content of northern, southern, and eastern lake water significantly decreased by more than 20%, 25%, and 30%, respectively. Our study demonstrated that water diversion significantly increased the annual endogenous TDS pollutant amount discharged from the lake and reduced and homogenized the TDS content of the whole lake. TDS content reduction of the lake was realized by water diversion accelerating water movement and water exchange in the lake, especially for the northern, southern, and eastern waters. Therefore, water diversion could be used as an effective measure for water quality improvement in semi-closed inland lakes in arid areas.

Sediment record in pollution, toxicity risk, and source assignment of polycyclic aromatic hydrocarbons (PAHs) in Erhai Lake, Southwest China

Surface sediments and sediment core had been collected from Erhai Lake, Southwest China to study the concentrations, toxicity risks, and sources of polycyclic aromatic hydrocarbons (PAHs). The average concentrations of Σ16PAHs, seven carcinogenic PAHs (carPAHs), and carcinogenic toxic equivalents (TEQcar) in the surface sediments and sediment core were 1634.50 ± 488.56 ng g−1 and 436.72 ± 128.17 ng g−1, 67.18–293.65 ng g−1 and 91.07–265.90 ng g−1, and 34.89 ± 13.17 ng g−1 and 36.99 ± 7.52 ng g−1, respectively. The Σ16PAHs and carPAHs concentrations in surface sediments were higher in the southern lake. The Σ16PAHs and TEQcar in the sediment core peaked in the 2010s and 1980s. The spatiotemporal variations in TEQcar and carPAHs were similar. Positive matrix factorization revealed that traffic emissions contributed 35.71 % of the TEQcar, whereas coal and biomass combustion contributed 12.89 % in the surface sediments. The contribution of gasoline and fossil fuel to TEQcar significantly increased from 19.2 % (1890s) to 66.5 % (1990s), that of benz[a]pyrene (coal combustion) decreased, and those of benz[b]fluoranthene and indeno[1,2,3-cd]pyrene (petroleum combustion and traffic emissions) increased from 1.92 % to 3.93 % and from 1.54 % to 2.52 % in the sediment cores, respectively, owing to changes in energy consumption.

Acanthogammarus victorii (Crustacea, Amphipoda) Cast Ashore in Southern Lake Baikal in December 2013: Possible Causes

Acanthogammarus victorii (Crustacea, Amphipoda) Cast Ashore in Southern Lake Baikal in December 2013: Possible Causes

Nature or nurture: a genetic basis for the behavioral selection of depth in siscowet and lean lake char (Salvelinus namaycush) ecomorphs

Leans and siscowets are lake char ecomorphs in Lake Superior that exhibit distinct depth selection behavior in the wild with leans occupying shallow (<50 m) depths and undergoing small vertical movements. In contrast, siscowets exhibit several types of depth selection behavior but generally remain at great depths (>80 m) and undergo extreme vertical movements. The present study used movement and temperature data from popup satellite archival tags (PSATs) to test the hypothesis that the difference in depth selection behavior of leans and siscowets is a genetic trait. Laboratory leans and siscowets produced from wild gametes taken from Lake Superior and reared in a common garden study for nine years were tagged with PSATs and released in southern Lake Superior. Tagged siscowets remained deep after release and exhibited extensive vertical movements. Most tagged leans remained <50 m after deployment and exhibited smaller vertical movements. Overall, the depths and temperatures occupied by the laboratory ecomorphs were significantly different throughout the deployment and the results support the hypothesis that depth selection in lake char ecomorphs is heritable.