湖水含盐量和Cu^(2+)浓度变化对Kinneret湖浮游植物的影响

通过人为改变湖水中的Cu2 + 浓度和含盐量的方法 ,Cu2 + 浓度和含盐量变化对Kinneret湖水中浮游植物可能造成的影响进行了分析。结果表明 ,湖水Cu2 + 浓度增加会抑制Kinneret湖水中藻类等浮游植物的生长 ,这对改善湖水水质来说是非常有利的 ,但高的Cu2 + 浓度对农作物生长和人类健康是有害的。在另一方面 ,对含盐量较低的约旦河水来说 ,适当增加Cu2 + 浓度则有利于藻类的生长。Kinneret湖中浮游植物的年平均生物量随湖水含盐量的下降而有增加的趋势 ,特别是当含盐量低于 2 0 0 μg/L左右时 ,浮游植物中蓝藻占的比例会升高 ,这对作为饮用水资原的Kinneret湖水来说是不利的。由此可见 ,适当控制和维持Kinneret湖水Cu2 + 浓度和含盐量对湖水水质保护具有重要的意义。

人为因素导致的盐度变化对Kinneret湖水细菌种群的影响

由于Ｋｉｎｎｅｒｅｔ湖周围的诸多盐泉被人为地导入其下游的约旦河，使得Ｋｉｎｎｅｒｅｔ湖水的盐度逐渐下降，这对作为主要工农业用水和饮用水资源的Ｋｉｎｎｅｒｅｔ湖来说是非常有价值的。然而，对湖水中的细菌来说则可能产生不同的影响。作者通过实验研究发现，湖水盐度的变化导致细菌种群的改变，从而使我们观察到盐度与细菌之间的关系。这些结果表明：盐度变化对湖水水质保护对策和将来一段时间内湖水管理政策的制定都具有重要的意义。

多甲藻对不同光照强度的反应:色素沉着及暗光适应的可能性(英文)

在ＨＰＬＣ色素分析的基础上，研究了多甲藻对不同光照强度（１６．６—２５０μ·Ｅｍ－２ｓ－１） 的反应。类胡萝卡素中最重要的多甲藻素和硅甲藻黄素占叶黄素总量的９０％。随光照强度的 逐步增加，多甲藻细胞中叶绿素ａ含量呈现明显的下降趋势。结果表明硅甲藻黄素和β胡萝卜 素具有光保护作用：１）当多甲藻暴露于较强光下时，硅甲藻黄素／叶绿素ａ之比呈现出明显增 加的趋势。β胡萝卜素／叶绿素ａ之比也显现出明显的增加趋势。２）β胡萝卜素／叶绿素ａ之比 在有光条件下比在完全黑暗条件下要高；３）硅甲藻黄素／叶绿素ａ之比在高辐照度、低辐照 度，及由高到低、由低到高辐照度处理时，显示出组间差异。由此可推出色素代谢可能的途径 及其湖沼学意义。

Water Quality Assessment, Trophic Classification and Water Resources Management

Quantification of water quality (WQ) is an integral part of scientifically based water resources management. The main objective of this study was comparative analysis of two approaches applied for quantitative assessment of WQ: the trophic level index (TLI) and the Delphi method (DM). We analyzed the following features of these conceptually different approaches: A. similarity of estimates of lake WQ;B. sensitivity to indicating disturbances in the aquatic ecosystem structure and functioning;C. capacity to reflect the impact of major management measures on the quality of water resources. We compared the DM and TLI based on results from a series of lakes covering varying productivity levels, mixing regimes and climatic zones. We assumed that the conservation of aquatic ecosystem in some predefined, “reference”, state is a major objective of sustainable water resources management in the study lakes. The comparison between the two approaches was quantified as a relationship between the DM ranks and respective TLI values. We show that being a classification system, the TLI does not account for specific characteristics of aquatic ecosystems and the array of different potential uses of the water resource. It indirectly assumes that oligotrophication is identical to WQ improvement, and reduction of economic activity within the lake catchment area is the most effective way to improve WQ. WQ assessed with the TLI is more suitable for needs of natural water resources management if eutrophication is a major threat. The DM allows accounting for several water resource uses and therefore it may serve as a more robust and comprehensive tool for WQ quantification and thus for sustainable water resources management.

The effect of cylindrospermopsin on the bacterioplankton community:a microcosm experiment on water from Dishui Lake,Shanghai,China

Eutrophication and climate warming have intensified the global expansion of invasive cyanobacteria such as Cylindrospermopsis spp.and Chrysosporum spp.Cylindrospermopsin(CYN)produced by species of the latter two genera may harm phytoplankton,zooplankton,and fishes.However,effects of CYN on the bacterioplankton community have not been studied.Based on high-throughput sequencing,we explored the effect of CYN on the structure and function of the bacterioplankton community by adding pure CYN to in-situ water collected from a brackish coastal shallow lake:Dishui Lake,China.We found that most bacterioplankton taxa had a certain tolerance potential to CYN,but that high concentrations of CYN(40μg/L)caused a significant decrease in microbial abundance and functional groups.Of the dominant phyla,Actinobacteria had the strongest tolerance to CYN.Network analysis indicated that CYN caused shifts in the community structure of the bacterioplankton,reducing community stability and structural complexity.High CYN concentrations also reduced the correlation between the different bacterioplankton groups,and the abundances of some bacterial taxa associated with the denitrification function and the process of carbon transfer in the microbial food web were inhibited.Our study provide s new insight into the response of the bacterioplankton communities to harmful algal toxins produced by cyanobacteria.

FISH FAUNA OF THE HWAJINPO LAKE,KOREA

The Fish fauna of the Hwajinpo Lake,one of the lagoons on the east coast of Korea,was investigated during six days between November,2003 and May,2004.Fifteen species belonging to eight families and six orders were collected.Among the 15 species recorded,brackish water and/or marine fishes were represented by six species,while three additional species were identified as migratory fish,and six species were purely freshwater fish.During the six months,all of the survey period with six sampling dates,nine species belonging to six families were collected at Station 1,with Chaenogobius urotaenia presenting the highest biomass (39%).Twelve species belonging to six families were collected at Station 2,with Carassiu cuvieri showing the highest biomass (20%).Five species belonged to three families at Station 3,with Hemiculter eigenmanni showing the highest biomass (69%).The dominant and subdominant species were C.cuvieri (16%),Carassius auratus and Tribolodon hakonensis (14%),respectively.Also,diversity indices were 0.95 (Station 3) and 2.08 (Station 2),while the dominant indices were 38.40 (Station 2) and 87.18 (Station 3).The evenness indices were calculated with 0.59 (Station 3) and 0.84 (Station 2).

Importance of periphytic biofilms for carbon cycling in paddy fields:A review

Paddy fields play an important role in global carbon(C) cycling and are an important source of methane(CH_(4)) emissions. Insights into the processes influencing the dynamics of soil organic C(SOC) in paddy fields are essential for maintaining global soil C stocks and mitigating climate change. Periphytic biofilms composed of microalgae, bacteria, and other microorganisms are ubiquitous in paddy fields, where they directly mediate the transfer of elements at the soil-water interface. However, their contributions to C turnover and exchange have been largely neglected. Periphytic biofilms affect and participate in soil C dynamics by altering both abiotic(e.g., pH and redox potential) and biotic conditions(e.g., microbial community composition and metabolism). This review summarizes the contributions of periphytic biofilms to soil C cycling processes, including carbon dioxide fixation, SOC mineralization, and CH_(4) emissions. Future research should be focused on: i) the mechanisms underlying periphytic biofilm-induced C fixation and turnover and ii) quantifying the contributions of periphytic biofilms to soil C uptake, stabilization, and sequestration in paddy fields.

Composition regulates dissolved organic matter adsorption onto iron (oxy)hydroxides and its competition with phosphate: Implications for organic carbon and phosphorus immobilization in lakes

Dissolved organicmatter(DOM)is a heterogeneous pool of compounds and exhibits diverse adsorption characteristics with or without phosphorous(P)competition.The impacts of these factors on the burial and mobilization of organic carbon and P in aquatic ecosystems remain uncertain.In this study,an algae-derived DOM(ADOM)and a commercially available humic acid(HA)with distinct compositions were assessed for their adsorption behaviors onto iron(oxy)hydroxides(FeOx),both in the absence and presence of phosphate.ADOM contained less aromatics but more protein-like and highly unsaturated structures with oxygen compounds(HUSO)than HA.The adsorption capacity of FeOx was significantly greater for ADOM than for HA.Protein-like and HUSO compounds in ADOM and humic-like compounds and macromolecular aromatics in HA were preferentially adsorbed by FeOx.Moreover,ADOM demonstrated a stronger inhibitory effect on phosphate adsorption than HA.This observation suggests that the substantial release of autochthonous ADOM by algae could elevate internal P loading and pose challenges for the restoration of restore eutrophic lakes.The presence of phosphate suppressed the adsorption of protein-like compounds in ADOM onto FeOx,resulting in an increase in the relative abundance of protein-like compounds and a decrease in the relative abundance of humic-like compounds in post-adsorption ADOM.In contrast,phosphate exhibited no discernible impact on the compositional fractionation of HA.Collectively,our results show the source-composition characters of DOM influence the immobilization of both DOM and P in aquatic ecosystems through adsorption processes.The preferential adsorption of proteinaceous compounds within ADOM and aromatics within HA highlights the potential for the attachment with FeOx to diminish the original source-specific signatures of DOM,thereby contributing to the shared DOM characteristics observed across diverse aquatic environments.

Corrigendum to“Optical measurements of dissolved organic matter as proxies for COD_(Mn)and BOD_(5)in plateau lakes”[Environ.Sci.Ecotech.19(2024)100326]

The authors regret that the following statements in the original article were wrong and have been corrected.The authors would like to apologise for any inconvenience caused.

Corrigendum to“Optical measurements of dissolved organic matter as proxies for COD_(Mn)and BOD_(5)in plateau lakes”[Environ.Sci.Ecotech.19(2024)100326]

The authors regret that the following statements in the original article were wrong and have been corrected.The authors would like to apologise for any inconvenience caused.

Optical measurements of dissolved organic matter as proxies for COD_(Mn)and BOD_(5)in plateau lakes

The presence of organic matter in lakes profoundly impacts drinking water supplies,yet treatment processes involving coagulants and disinfectants can yield carcinogenic disinfection by-products.Traditional assessments of organic matter,such as chemical oxygen demand(COD_(Mn))and biochemical oxygen demand(BOD_(5)),are often time-consuming.Alternatively,optical measurements of dissolved organic matter(DOM)offer a rapid and reliable means of obtaining organic matter composition data.Here we employed DOM optical measurements in conjunction with parallel factor analysis to scrutinize COD_(Mn)and BOD_(5)variability.Validation was performed using an independent dataset encompassing six lakes on the Yungui Plateau from 2014 to 2016(n=256).Leveraging multiple linear regressions(MLRs)applied to DOM absorbance at 254 nm(a254)and fluorescence components C1-C5,we successfully traced COD_(Mn)and BOD_(5)variations across the entire plateau(68 lakes,n=271,R^(2)>0.8,P<0.0001).Notably,DOM optical indices yielded superior estimates(higher R^(2))of COD_(Mn)and BOD_(5)during the rainy season compared to the dry season and demonstrated increased accuracy(R^(2)>0.9)in mesotrophic lakes compared to oligotrophic and eutrophic lakes.This study underscores the utility of MLR-based DOM indices for inferring COD_(Mn)and BOD_(5)variability in plateau lakes and highlights the potential of integrating in situ and remote sensing platforms for water pollution early warning.

Response of community composition and biomass of submerged macrophytes to variation in underwater light, wind and trophic status in a large eutrophic shallow lake

Light climate is of key importance for the growth, community composition of submerged macrophytes in lakes and, they, in turn, are affected by lake depth and the degree of eutrophication. To test the relationships between submerged macrophyte presence and the ratio of Secchi disk depth(SDD) to water depth, i.e. SDD/depth, nutrients and wind, we conducted an extensive sampling campaign in a macrophyte-dominated area of the eastern region( n = 36) in 2016 in Lake Taihu, China, and combined the data gathered with results from extensive physico-chemical monitoring data from the entire lake. We confirmed that SDD/Depth is the primary factor controlling the community composition of macrophytes and showed that plant abundance increased with increasing SDD/Depth ratio( p < 0.01), but that only SDD/Depth > 0.4 ensured growth of submerged macrophytes. Total phosphorus and total nitrogen also influenced the growth and community composition of macrophytes( p < 0.01), while Chl a was an indirectly affecting factor by reducing underwater light penetration. Wave height significantly influenced plant abundance( p < 0.01), whereas it had little effect on the biomass( p > 0.05). The key to restore the macrophyte beds in the lake is to reduce the nutrient loading. A decrease of the water level may contribute as well in the shallow bays but will not bring plants back in the main part of the lake. As the tolerance of shade and nutrients varied among the species studied, this should be taken into account in the restoration of lakes by addition of plants.

Importance and vulnerability of lakes and reservoirs supporting drinking water in China

Drinking water is closely related to human health,disease and mortality,and contaminated drinking water causes 485,000 deaths from diarrhea each year worldwide.China has been facing increasingly severe water scarcity due to both water shortages and poor water quality.Ensuring safe and clean drinking water is a great challenge and top priority,especially for China with 1.4 billion people.In China,more than 4000 centralized drinking water sources including rivers,lakes and reservoirs,and groundwater have been established to serve urban residents.However,there is little knowledge on the percentage,serving population and water quality of three centralized drinking water source types.We collected nationwide centralized drinking water sources data and serving population data covering 395 prefecture-level and county-level cities and water quality data in the two most populous provinces(Guangdong and Shandong)to examine their contribution and importance.Geographically,the drinking water source types can be classified into three clear regions exhibiting apparent differences in the respective contributions of rivers,lakes and reservoirs,and groundwater.We further found that overall,lakes and reservoirs account for 40.6%of the centralized drinking water sources vs.river(30.8%)and groundwater(28.6%)in China.Lakes and reservoirs are particularly important in the densely populated eastern region,where they are used as drinking water sources by 51.0%of the population(318 million).Moreover,the contribution to the drinking water supply from lakes and reservoirs is increasing due to their better water quality and many cross-regional water transfer projects.These results will be useful for the government to improve and optimize the establishment of centralized drinking water sources,which provide safe and clean drinking water in China to safeguard people's lives and health and realize sustainable development goals.

Biodegradable dissolved organic carbon shapes bacterial community structures and co-occurrence patterns in large eutrophic Lake Taihu

Interactions between dissolved organic matter(DOM)and bacteria are central in the biogeochemical cycles of aquatic ecosystems;however,the relative importance of biodegradable dissolved organic carbon(BDOC)compared with other environmental variables in structuring the bacterial communities needs further investigation.Here,we investigated bacterial communities,chromophoric DOM(CDOM)characteristics and physico-chemical parameters as well as examined BDOC via bioassay incubations in large eutrophic Lake Taihu,China,to explore the importance of BDOC for shaping bacterial community structures and co-occurrence patterns.We found that the proportion of BDOC(%BDOC)correlated significantly and positively with the DOC concentration and the index of the contribution of recent produced autochthonous CDOM(BIX).%BDOC,further correlated positively with the relative abundance of the tryptophan-like component and negatively with CDOM aromaticity,indicating that autochthonous production of protein-like CDOM was an important source of BDOC.The richness of the bacterial communities correlated negatively with%BDOC,indicating an enhanced number of species in the refractory DOC environments.%BDOC was identified as a significant stronger factor than DOC in shaping bacterial community composition and the co-occurrence network,suggesting that substrate biodegradability is more significant than DOC quantity determining the bacterial communities in a eutrophic lake.Environmental factors explained a larger proportion of the variation in the conditionally rare and abundant subcommunity than for the abundant and the rare bacterial subcommunities.Our findings emphasize the importance of considering bacteria with different abundance patterns and DOC biodegradability when studying the interactions between DOM and bacteria in eutrophic lakes.

Human impact on current environmental state in Chinese lakes

Anthropogenic and natural disturbance to inland aquatic ecosystems displays a notable spatial difference, yet data to measure these differences are scarce. This study encompasses 217 lakes distributed over five lake regions of China and elucidates the environmental factors determining the spatial variability of the water quality and trophic status. A significant correlation between human modification index in surrounding terrestrial systems(HMT)and trophic status of lake ecosystems(TSI) was found, and the regression slope in each region was similar except in the Qinghai-Tibet Plateau region. It was further noted that the pattern of environmental factor network(EF network) differed among freshwater and saline lakes. The EF network was complex for freshwater lakes in less human-influenced areas, but intensive man-made influence disrupted most relationships except for those between total nitrogen, total phosphorus, chlorophyll-a, and water turbidity. As for regions including saline lakes, correlations among water salinity and organic forms of carbon and nitrogen were apparent. Our results suggest that HMT and EF network can be useful indicators of the ecological integrity of local lake ecosystems, and integrating spatial information on a large scale provides conservation planners the option for evaluating the potential risk on inland aquatic systems.

气候变化驱动湖泊快速变暖和热浪增加

气候变化导致的湖泊表层水体变暖和热浪增加可能严重威胁湖泊生态系统.由于大尺度模拟时,湖泊模型精度受限,故对湖泊水温变化的准确量化依然存在不确定性.本研究以中国湖泊为例,采用了一种耦合卫星观测水温和湖泊物理模型的方法模拟了1980-2100年间的水温,并探索了水温在多方面的变化.研究发现1980-2021年间中国湖泊表层水温以0.11℃/10a的速率上升,约为使用单独湖泊模型模拟结果的一半.湖泊水温在不同季节、不同地区的非对称增温导致水温的春夏季季节性在中国东部平原湖泊减弱,在高原湖泊增强.伴随湖泊水温的长期上升趋势,湖泊热浪的持续时间平均每10年延长7.7天.在温室气体高排放情景下,21世纪末湖泊表层水温的气候态年均值相比历史时期将增加2.2℃热浪的年持续时间将增加197天.湖泊物理环境的剧变意味着湖泊将面临严重的人类活动压力,这会进一步威胁水生生态系统的生物多样性和人类健康.

罕见极端高温事件导致中国湖泊急剧变暖

在气候变化背景下,全球极端事件近年来显著增加,严重威胁湖泊生态系统健康及生态服务功能.本研究基于2000~2022年MODIS卫星遥感数据,量化了2022年罕见极端高温事件对我国湖泊的影响.结果表明,该极端高温事件导致中国湖泊表层水温平均升高了1.63℃,远超过去20年的增温幅度.其中,淮河流域和西南诸河流域湖泊受此影响最为明显,分别升高了2.01和1.81℃.不仅如此,该事件引发了长江流域严重干旱,造成鄱阳湖水位下降了55.07%、面积减少了73.32%,从而导致鱼类等水生生物大量死亡、鸟类失去栖息地,多地饮用水短缺.

Metagenomic analysis to determine the characteristics of antibiotic resistance genes in typical antibiotic-contaminated sediments

Comprehensive studies of the effects of various physical and chemical variables(including heavymetals),antibiotics,and microorganisms in the environment on antibiotic resistance genes are rare.We collected sediment samples from the Shatian Lake aquaculture area and surrounding lakes and rivers located in Shanghai,China.The spatial distribution of sediment ARGs was assessed by metagenomic analysis that revealed 26 ARG types(510 subtypes),dominated by Multidrug,β-lactam,Aminoglycoside,Glycopeptides,Fluoroquinolone,and Tetracyline.Redundancy discriminant analysis indicated that antibiotics(SAs and MLs)in the aqueous environment and sediment along with water TN and TP were the key variables affecting the abundance distribution of total ARGs.However,the main environmental drivers and key influences differed among the different ARGs.For total ARGs,the environmental subtypes affecting their structural composition and distribution characteristics were mainly antibiotic residues.Procrustes analysis showed a significant correlation between ARGs and microbial communities in the sediment in the survey area.Network analysis revealed that most of the target ARGs were significantly and positively correlated with microorganisms,and a small number of ARGs(e.g.,rpoB,mdtC,and efpA)were highly significantly and positively correlated with microorganisms(e.g.,Knoellia,Tetrasphaera,and Gem-matirosa).Potential hosts for the major ARGs included Actinobacteria,Proteobacteria,and Gemmatimonadetes.Our study provides new insight and a comprehensive assessment of the distribution and abundance of ARGs and the drivers of ARG occurrence and transmission.

Salinization Increase due to Climate Change Will Have Substantial Negative Effects on Inland Waters: A Call for Multifaceted Research at the Local and Global Scale

Globally,temperature and precipitation patterns are predicted to change markedly as a result of climate change.Particularly,the regions with a cold or hot semi-arid climate and the Mediterranean climate zone are expected to be strongly affected.1,2 A 25%–30%decrease in precipitation and increased evaporation are expected by the end of the 21st century in the Mediterranean region,to be accompanied by an even stronger reduction in runoff of up to 30%–40%,1,2 and this will lead to increasing salinization of lakes in these areas.

From unusual suspect to serial killer: Cyanotoxins boosted by climate change may jeopardize megafauna

The recent mass mortality event of more than 330 African elephants in Botswana has been attributed to biotoxins produced by cyanobacteria;however,scientific evidence for this is lacking.Here,by synthesizing multiple sources of data,we show that,during the past decades,the widespread hypertrophic waters in Southern Africa have entailed an extremely high risk and frequent exposure of cyanotoxins to the wildlife within this area,which functions as a hotspot of mammal species richness.The hot and dry climatic extremes have most likely acted as the primary trigger of the recent and perhaps also of prehistoric mass mortality events.As such climate extremes are projected to become more frequent in Southern Africa in the near future,there is a risk that similar tragedies may take place,rendering African megafauna species,especially those that are already endangered,in risk of extinction.Moreover,cyanotoxin poisoning amplified by climate change may have unexpected cascading effects on human societies.Seen within this perspective,the tragic mass death of the world's largest terrestrial mammal species serves as an alarming early warning signal of future environmental catastrophes in Southern Africa.We suggest that systematic,quantitative cyanotoxin risk assessments are made and precautionary actions to mitigate the risks are taken without hesitation to ensure the health and sustainability of the megafauna and human societies within the region.