Warming of surface water in the large and shallow lakes across the Yangtze River Basin,China, and its driver analysis

Environmental Science and Pollution Research - A variety of physical, chemical, and biological processes within the lakes relies on the surface water temperature while the spatial pattern of large...     

Effects of taxonomy,sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes,China

Carbon (C), nitrogen (N) and phosphorus (P) are the three most important essential elements limiting growth of primary producers. Submerged macrophytes generally absorb nutrients from sediments by root uptake. However, the C:N:P stoichiometric signatures of plant tissue are affected by many additional factors such as taxonomy, nutrient availability, and light availability. We first revealed the relative importance of taxonomy, sediment, and water column on plant C:N:P stoichiometry using variance partitioning based on partial redundancy analyses. Results showed that taxonomy was the most important factor in determining C:N:P stoichiometry, then the water column and finally the sediment. In this study, a significant positive relationship was found between community C concentration and macrophyte community biomass, indicating that the local low C availability in macrophytes probably was the main reason why submerged macrophytes declined in Yangtze floodplain shallow lakes. Based on our study, it is suggested that submerged macrophytes in Yangtze floodplain shallow lakes are primarily limited by low light levels rather than nutrient availability.

     

Complex interactions between autotrophs in shallow marine and freshwater ecosystems: implications for community responses to nutrient stress

The relative biomass of autotrophs (vascular plants, macroalgae, microphytobenthos, phytoplankton) in shallow aquatic ecosystems is thought to be controlled by nutrient inputs and underwater irradiance. Widely accepted conceptual models indicate that this is the case both in marine and freshwater systems. In this paper we examine four case studies and test whether these models generally apply. We also identify other complex interactions among the autotrophs that may influence ecosystem response to cultural eutrophication. The marine case studies focus on macroalgae and its interactions with sediments and vascular plants. The freshwater case studies focus on interactions between phytoplankton, epiphyton, and benthic microalgae. In Waquoit Bay, MA (estuary), controlled experiments documented that blooms of macroalgae were responsible for the loss of eelgrass beds at nutrient-enriched locations. Macroalgae covered eelgrass and reduced irradiance to the extent that the plants could not maintain net growth. In Hog Island Bay, VA (estuary), a dense lawn of macroalgae covered the bottom sediments. There was reduced sediment-water nitrogen exchange when the algae were actively growing and high nitrogen release during algal senescence. In Lakes Brobo (West Africa) and Okeechobee (FL), there were dramatic seasonal changes in the biomass and phosphorus content of planktonic versus attached algae, and these changes were coupled with changes in water level and abiotic turbidity. Deeper water and/or greater turbidity favored dominance by phytoplankton. In Lake Brobo there also was evidence that phytoplankton growth was stimulated following a die-off of vascular plants. The case studies from Waquoit Bay and Lake Okeechobee support conceptual models of succession from vascular plants to benthic algae to phytoplankton along gradients of increasing nutrients and decreasing under-water irradiance. The case studies from Hog Island Bay and Lake Brobo illustrate additional effects (modified sediment-water nutrient fluxes, allelopathy or nutrient release during plant senescence) that could play a role in ecosystem response to nutrient stress.     

Glyphosate input modifies microbial community structure in clear and turbid freshwater systems

Since it was commercially introduced in 1974, glyphosate has been one of the most commonly used herbicides in agriculture worldwide, and there is growing concern about its adverse effects on the environment. Assuming that glyphosate may increase the organic turbidity of water bodies, we evaluated the effect of a single application of 2.4?±?0.1 mg l^?1 of glyphosate (technical grade) on freshwater bacterioplankton and phytoplankton (pico, micro, and nanophytoplankton) and on the physical and chemical properties of the water. We used outdoor experimental mesocosms under clear and oligotrophic (phytoplanktonic chlorophyll a?=?2.04 μg l^?1; turbidity?=?2.0 NTU) and organic turbid and eutrophic (phytoplanktonic chlorophyll a?=?50.3 μg l^?1; turbidity?=?16.0 NTU) scenarios. Samplings were conducted at the beginning of the experiment and at 1, 8, 19, and 33 days after glyphosate addition. For both typologies, the herbicide affected the abiotic water properties (with a marked increase in total phosphorus), but it did not affect the structure of micro and nanophytoplankton. In clear waters, glyphosate treatment induced a trend toward higher bacteria and picoeukaryotes abundances, while there was a 2 to 2.5-fold increase in picocyanobacteria number. In turbid waters, without picoeukaryotes at the beginning of the experiment, glyphosate decreased bacteria abundance but increased the number of picocyanobacteria, suggesting a direct favorable effect. Moreover, our results show that the impact of the herbicide was observed in microorganisms from both oligo and eutrophic conditions, indicating that the impact would be independent of the trophic status of the water body.     

DGGE、T-RFLP 、LH-PCR对两种活性污泥的微生物种群多样性分析的比较

采用基于PCR扩增的分子生态技术DGGE、T-RFLP和LH-PCR,对2种典型污水处理系统中的活性污泥（生活污泥、焦化污泥）进行微生物种群多样性分析;并以此比较3种技术的优劣,提出不同应用条件下研究方法的选择依据。根据实验结果：DGGE得到的条带较多,但误差来源也最多;T-RFLP技术较为灵敏,但需要选择适当的内切酶,严格控制酶切条件,并且文库比对误差较大;而LH-PCR操作简单,结果稳定性较高。虽然目前尚无法判断3种方法的准确性,但LH-PCR在活性污泥的微生物种群多样性分析中已显示出潜在优势。     

Characteristics of organic phosphorus fractions in different trophic sediments of lakes from the middle and lower reaches of Yangtze River region and Southwestern Plateau, China

In this study, the characteristics of organic phosphorus (Po) fractions in sediments of six lakes from the middle and lower reaches of Yangtze River region and Southwestern China Plateau, China were investigated using a soil Po fractionation scheme, and the relationships between Po, inorganic phosphorus (Pi) and pollution status were also discussed. The results show that the rank order of Po fractions was: residual Po>HCl-Po>fulvic acid-P>humic acid-P>NaHCO3-Po, with their average relative proportion 8.7:4.6:3.2:2.1:1.0. Po fractions, especially nonlabile Po, were significantly correlated with organic matter, Po and NaOH-Pi. Different distribution patterns of P fractions were observed in those two different regions. Po fractions in the heavily polluted sediments were higher than those in moderately and no polluted sediments, it is suggested that Po should be paid more attention in the lake eutrophication investigation.     

强化氧化后污染源浅层地下水中氯苯类污染物的自然衰减与微生物群落演化

监控自然衰减技术通常与其他地下水修复技术联用,以降低修复成本、减少环境影响,目前该技术在氯苯类污染地块的实践应用案例存在空白,其效果及作用机制尚不明确。以原位臭氧氧化和化学氧化中试后的氯苯类污染地块为研究对象,从实际工程案例的角度,监测强化氧化措施后2年内的氯苯类化合物的降解速率、细菌组成,评价不同修复措施后污染物自然衰减能力、探讨作用机制。结果显示,经过727 d的自然衰减,1,2-二氯苯和1,4-二氯苯在臭氧氧化区和化学氧化区中的降解率都超过了90%。臭氧氧化区地下水中1,2-二氯苯和1,4-二氯苯的一阶降解速率常数分别为0.005 2 d⁻¹ (R²=0.857) 和0.006 0 d⁻¹ (R²=0.967) ;化学氧化区地下水中污染物质量浓度在416 d后出现回升,不符合一阶衰减模型。细菌16S rRNA的高通量分析表明,臭氧和过硫酸钠氧化改变了地下水中细菌群落结构,在自然衰减过程中细菌群落结构逐渐恢复,环境因子S²⁻、ORP和pH值与细菌群落结构显著相关。本地块2个区域中试后416 d内都以化学氧化和微生物好氧降解为主,后向微生物厌氧降解转变。本研究可为氯苯类污染地下水修复工程的绿色高效实施提供参考。     

Nutrient dynamics in shallow lakes of northern greece

GOAL, SCOPE, BACKGROUND: Shallow lakes display a number of features that set them apart from the more frequently studied deeper systems. The majority of lakes in Northern Greece are small to moderate in size with a relatively low depth and are considered as sites of high value of the wetland habitat. However, the water quality of these lakes has only been evaluated segmentally and occasionally. OBJECTIVE: The objectives of this study were to thoroughly investigate nitrogen and phosphorus speciation in lakes of a high ecological significance located in N. Greece, in order to evaluate their eutrophication status and possible nutrient limitation factors, and to investigate the main factors/sources that affect the water quality of these systems. METHODS: An extensive survey was carried out during the period from 1998-1999. Water samples were collected on a monthly basis from lakes Koronia, Volvi, Doirani, Mikri Prespa and Megali Prespa located in N. Greece. Water quality parameters (temperature, dissolved oxygen, pH and conductivity), organic indices (COD, BOD5), and N- and P-species (NO3(-), NO2(-), NH4(+), and PO4(3-), Kieldahl nitrogen and acid-hydrolysable phosphorus) were determined according to standard methods for surface water. Statistical treatment of the data was employed. RESULTS AND CONCLUSIONS: The physicochemical parameters determined in the lakes studied revealed a high temporal variation. The trophic state of the lakes ranged from meso- to hypertrophic. The nutrient limiting factor varied among lakes suggesting either P-limitation conditions or mixed conditions changing from P- to N-limitation throughout the year. Urban/industrial activities and agricultural runoff are the major factors affecting all lakes, although with a varying contribution. RECOMMENDATION AND OUTLOOK: This lake-specific research offers valuable information about water quality and nutrient dynamics in lakes of significant ecological value located in N. Greece that can be useful for an effective pollution control/management of these systems. Due to the large intra-annual variability of certain physicochemical parameters, a properly designed monitoring program of lake water is recommended.     

Hydrochemical characteristics and quality assessment of shallow groundwater in Yangtze River Delta of eastern China

Environmental Science and Pollution Research - Water resource is in high demand within the Yangtze River Delta, given its developed economy. Long-term exploitation of this resource has posed risks...     

Short-term effects of diesel fuel on rhizosphere microbial community structure of native plants in Yangtze estuarine wetland

Purpose

In this work, short-term effects of diesel fuel on Huangpu?CYangtze estuarine wetland soil microbial community structure were studied under simulated conditions through phospholipid fatty acids (PLFAs) analysis. Four native plant species, bulrush (Scirpus tripueter), galingale (Cyperus rotundus), wildrice (Zizania latifolia), and reed (Phragmites australis) were tested in the experiments.

Method

In the pot experiment, 20?g rhizosphere soils were mixed with 20?g diesel-blended soils. The concentration of total petroleum hydrocarbon was 16,000?mg/kg. All pots were incubated for 14?days in dark at 28°C and watered with 12?mL sterile distilled water to keep a liquid level. Microbial activity of the samples was assessed by hydrolysis of fluorescein diacetate. Measurements of soil PLFAs and analysis on gas chromatography were performed.

Results

The microbial activity in the samples of reed was highest after the exposure. In all samples, the common PLFA was straight-chain saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA). After the exposure the relative abundance of MUFA and polyunsaturated fatty acid decreased by 20%, and the relative abundance of straight-chain SFA increased by 20%. The results of diversity and PCA indicated that the effect of diesel pollutant on the microbial community was far stronger than the root effect and the reed roots enhanced the tolerance of soil microorganisms to diesel significantly.

Conclusions

All results showed that the soil microbial community structure differed significantly with the exposure to diesel. In reed rhizosphere, the soil microorganisms exhibited a strong resistance to diesel fuel. It confirmed that the root of reed improved the biodegradation ability of soil microorganisms for diesel pollutants and they could be reasonably matched to cure and restore the ecological environment of oil-contaminated wetlands.     

Interactions between a polycyclic aromatic hydrocarbon mixture and the microbial communities in a natural freshwater sediment

The toxicity of a polycyclic aromatic hydrocarbon (PAH) mixture was assessed on the indigenous microbial communities of a natural freshwater sediment. The fate and effects of the PAH mixture (phenanthrene, fluoranthene and benzo(k)fluoranthene) were studied over 28 days. Bacterial communities were described by bacterial counts (total bacteria and viable bacteria), and by some hydrolytic enzyme activities (beta-glucosidase and leucine-aminopeptidase), PAH concentrations were measured in the overlying waters and in the sediments. No effect of PAH was detected at 30 mg/kg for all bacterial parameters. At 300 mg/kg, the quantity of total bacteria and the proportion of viable bacteria markedly decreased, compared to the control (0 mg PAH/kg). At 300 mg/kg, an increase of the beta-glucosidase activity and a decrease of the leucine-aminopeptidase activity were observed. For all treatments, the benzo(k)fluoranthene concentration in the sediment was stable over 28 days whereas, in the same time, only 3-6% of the initial concentrations of phenanthrene and fluoranthene remained. This study shows that (1) PAH induce perturbations of sediment microbial communities in terms of density and metabolism (but not always as an inhibition), (2) indigenous bacteria of sediments might be used for toxicity assessment of specific organic pollutants, (3) native microorganisms of sediment seem to have a high capacity for PAH degradation, depending on the physico-chemical properties and the bioavailability of the substance encountered.     

Comparison of the purification performance and microbial community functional diversity in flow-directional-switching and unidirectional-flow biotrickling filters

Because of the characteristics of low operating cost and convenient operation, the biotrickling filter is extensively researched and used to treat low concentration waste gas contaminated by volatile organic compounds (VOCs) and other odors. In this paper, two laboratory-scale biotrickling filters were constructed and toluene was selected as the sole carbon source, and the effects of different waste-gas flow configuration patterns on the purification capacity and the microbial community functional diversity of biotrickling filters were evaluated. The results indicated that the flow-directional-switching (FDS) biotrickling filter had better purification performance, and the maximum elimination capacity reached 480 g·m^?3·hr^?1, which was 17.1% higher than conventional unidirectional-flow (UF) biotrickling filter. Comparing the purification capacities of different sections in two biotrickling filters, the maximum toluene elimination capacity of section III in FDS system could reach 542 g·m^?3·hr^?1, which was 2.8 times as great as that in UF system, which resulted from the difference of elimination capacity in two systems. By analyzing the metabolic activity of two systems by community-level physiological profiling (CLPP) with Biolog (Biolog Inc., Hayward, CA) ECO-plate technique, metabolic activity in three sections of FDS system was higher than that of UF system. The metabolic activity was the highest in section III of FDS system and 46.8% higher than that of UF system. Shannon index and McIntosh index of section III in FDS system were 6.2% and 31.5% higher, respectively, than those of UF system.

Implications: The flow-directional-switching (FDS) biotrickling filter had a better purification performance than unidirectional-flow (UF) biotrickling filter at high inlet loadings, because FDS produced a more uniform distribution of biomass and microbial metabolic capacity along the length of the packed bed without diminishing activity and removal capacity in the inlet section.     

Conventional and emerging halogenated flame retardants (HFRs) in sediment of Yangtze River Delta (YRD) region,East China

The occurrence and distribution of polybrominated diphenyl ethers (PBDEs) and eleven non-PBDE halogenated flame retardants (HFRs) were investigated through the collection of marine and river sediment from Yangtze River Delta (YRD), East China. Among them, PBDEs, decabromodiphenyl ethane (DBDPE) and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH) were the three predominant HFRs with the highest detection frequencies in the sediment. Significant correlation between PBDEs and DBDPE indicated that they may have the similar emission sources. The production and use of DBDPE is growing rapidly and comparable concentrations between PBDEs and DBDPE in YRD sediment may suggest that DBDPE will likely become one of the major HFRs emerging in the environment in China. Of the seven detected non-PBDE HFRs, this is the first time that TBECH was reported in the Chinese environment and its predominance and prevalence in the YRD may imply its extensive use in these areas.     

Hydrogeological and biogeochemical constrains of arsenic mobilization in shallow aquifers from the Hetao basin, Inner Mongolia

Little is known about the importance of drainage/irrigation channels and biogeochemical processes in arsenic distribution of shallow groundwaters from the Hetao basin. This investigation shows that although As concentrations are primarily dependent on reducing conditions, evaporation increases As concentration in the centre of palaeo-lake sedimentation. Near drainage channels, groundwater As concentrations are the lowest in suboxic-weakly reducing conditions. Results demonstrate that both drainage and irrigation channels produce oxygen-rich water that recharges shallow groundwaters and therefore immobilize As. Groundwater As concentration increases with a progressive decrease in redox potential along the flow path in an alluvial fan. A negative correlation between SO₄²⁻ concentrations and δ³⁴S values indicates that bacterial reduction of SO₄²⁻ occurs in reducing aquifers. Due to high concentrations of Fe (>0.5 mg L⁻¹), reductive dissolution of Fe oxides is believed to cause As release from aquifer sediments. Target aquifers for safe drinking water resources are available in alluvial fans and near irrigation channels.     

贫营养条件下2种MBR污泥微生物的菌群对比

为了揭示贫营养环境下MBR污泥微生物群落结构的演替和菌群变化的异同,取洗浴再生水、工业再生水MBR的污泥进行周期培养,利用PCR-DGGE和克隆测序技术获得了DNA指纹图谱并建立系统发育树。研究表明,微生物群落结构在贫营养条件下演替明显,洗浴水污泥微生物形成新的优势菌群(Uncultured Pseudomonas)而工业水只维持了原有的部分菌群(Uncultured Sphaerotilus)。2种污泥培养过程中种群多样性变化突出且差异显著。同时洗浴水污泥菌群相似性在培养第8天时发生突变而工业水总体变化平缓。克隆测序表明2种MBR污泥中既有与贫营养环境适生的共性种属又有与各自来源相对应的特性种属。菌群特异性与废水来源紧密相关,是造成2种污泥对贫营养环境适应能力不同的根本原因。     

Levels and body distribution of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in freshwater fishes from the Yangtze River, China

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) were determined in muscle, liver and eggs of freshwater fishes from the lower reach of the Yangtze River, China. The present study is the first to report HBCD concentrations in the environment of China. The concentrations of PBDEs and HBCDs in muscle of freshwater fishes from the Yangtze River ranged from 18 to 1100ng/g and 12 to 330ng/g lipid weight (wt.), respectively. When compared with other regions of the world, the contamination of PBDEs in biota could be regarded as moderate, whereas contamination of HBCDs in biota was relatively high. The PBDE congener profiles in fishes of the present study were markedly different from those observed in freshwater and marine fishes from other regions of the world. In the present study, BDE-15, BDE-28 and BDE-47 were the predominant congeners in the fishes. This particular congener profile in fishes from the Yangtze River revealed that a specific commercial PBDE formulation (probably made in China) might have been used in the Yangtze River Delta region.     

Divergent toxicity of parathion in two freshwater invertebrates, orconectes rusticus and viviparus malleatus

The toxicity of parathion and its metabolite paraoxon was examined in the crayfish Orconectes rusticus and the snail Viviparus malleatus and attempts were made to relate this to parathion uptake and metabolism. The crayfish was found to be very susceptible with all animals tested dying at 0.1 ppb of parathion in 48 hours. The snail was resistant to exposure to 1000 ppm. The absence of lethality even to injected (50 mg/kg) parathion and paraoxon suggests an innate lack of susceptibility. Metabolism of the compounds could not be detected in vitro or in vivo in either species.