大庆湖泊群水体和淡水鱼中多环芳烃污染特征及生态风险评估

2012年2~4月采集大庆湖泊群18个典型湖泊30个水体和36个鱼体样品,并对水体和5种鱼组织(鱼鳃、肝脏、鱼脑、肾脏和肌肉)样品中16种多环芳烃(PAHs)浓度进行分析测定.结果显示,水中PAHs总量为0.2~1.21μg·L-1,浓度最高值出现在月亮泡.利用统计学聚类分析方法对18个湖泊水体PAHs浓度进行分类,并进一步应用PAHs比值分析和物种敏感性分布模型对不同湖泊组湖泊水体PAHs分别进行来源分析和生态风险评估.结果表明,18个湖泊水体PAHs浓度统一聚类分成4个湖泊组,其中月亮泡(YLP)和东大海(DDH)两个湖泊分别单独成一类,其他14个湖泊被聚类分为XHH组和DQSK组两个湖泊组.湖泊水体中PAHs除了YLP组主要来自石油污染,其他湖泊PAHs的输入均为木柴和煤燃烧所致.根据国际和国内地表水环境质量标准,大庆湖泊群4个湖泊组水体PAHs浓度水平均有不同程度超标.其中YLP组和XHH组大部分水样中PAHs浓度超出美国环保署(US EPA)规定的16种PAHs限量值,尤其YLP组中致癌性最强的苯并[a]芘浓度已经超过了我国地表水环境质量标准;而DQSK组和DDH组也有少量几种PAHs超出水质标准.大庆湖泊群鲤鱼种和鲢鱼种5种组织器官内16种PAHs浓度检测结果及统计分析结果显示,除鲤鱼鳃中的蒽浓度显著高于鲢鱼鳃,其他15种PAHs在两类鱼种中无显著差异.而同鱼种不同组织器官中PAHs浓度存在明显差异性,肝脏和肾脏作为污染物外源传播的主要器官,其浓度明显高于肌肉、鳃和脑组织中PAHs的浓度,是PAHs在鱼体内累积的重要器官.对水生生物的生态风险和淡水鱼消费健康风险评估结果显示,4个典型湖泊组水体中PAHs对水生生物生态风险均较小,鲤鱼和鲢鱼鱼肉消费也均无饮食健康风险.     

四环素类抗生素对淡水绿藻的毒性作用

四环素类抗生素是目前世界上应用最为广泛的抗生素之一,也是我国畜禽养殖业中使用量最大的兽药和饲料添加剂.由于该类物质不易被生物体吸收且当前的污水处理设施对抗生素不能彻底去除,故大量抗生素及其代谢产物最终进入地表水环境,其对水生态系统和人体健康的潜在威胁值得关注.本研究以水生态系统初级生产者淡水绿藻为受试生物,系统考察四环素、金霉素和强力霉素对蛋白核小球藻、斜生栅藻细胞膜通透性和生长抑制作用的影响.结果表明,抗生素暴露96 h后,强力霉素在整个作用浓度范围内使供试淡水绿藻细胞膜通透性降低;而金霉素和四环素低浓度暴露可以增大藻细胞膜通透性,此后随着作用浓度的增大转为降低.3种抗生素对淡水绿藻生长抑制率大致呈现强力霉素>四环素>金霉素的顺序趋势.斜生栅藻对四环素类抗生素的毒性响应较蛋白核小球藻更为敏感.     

Effects of elevated CO2 concentration and nitrogen supply on biomass and active carbon of freshwater marsh after two growing seasons in Sanjiang Plain, Northeast China

An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m²) and CO₂ levels (350 and 700 μmol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO₂ concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO₂ concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO₂ elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO₂ concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m²). Elevated CO₂ concentration also increased the allocation of biomass and carbon in root. Under elevated CO₂ concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) > dissolved organic carbon (7.5%) > labile oxidable carbon (6.6%) > carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO₂ concentration.     

流域水生态功能区概念、特点与实施策略

我国正处在从传统的水质管理向水生态管理转变的关键阶段,水生态功能区是实施流域水生态系统管理的基本单元. 结合区划理论的发展,对国内外区划研究进展进行了系统总结,界定了水生态功能区的基本概念,提出了水生态功能区的基本特点及其在环境管理中的主要作用,辨析了水生态功能区与水功能区、生态功能区和主体功能区的关系,提出了水生态功能区实施的政策保障体系. 结果表明,水生态功能区是开展水生态系统健康评估、识别水生态功能和确定水生态保护目标的基本单元,具有基于流域单元进行划分、以水生态系统等级结构为主线、区域区划与类型区划相统一、陆地与水体保持一致性等特点;不同功能区在基本概念、法律和政策依据、分区目的、分区体系、分区指标和方法及其在管理中的作用等方面差异显著,水生态功能区是对上述功能区的发展、补充和完善;作为一个崭新概念,水生态功能区的实施需要从法律、机构、政策和技术等方面全面保障,在此基础上构建流域水环境综合管理技术体系,支撑流域生态文明建设.      

应用物种敏感性分布评价敌敌畏对淡水生物的生态风险

敌敌畏是一类重要的有机磷杀虫剂,但其对水生生态的影响至今研究较少。为了评价其生态风险,构建了淡水水生生物对敌敌畏的物种敏感性分布(species sensitivity distribution,SSD)模型,在此基础上,讨论了影响SSD模型的主要因素;并分析了该模型的不确定性;推导了敌敌畏对不同类别生物的5%危害浓度HC5(hazardous concentration for 5%the species)阈值;整理收集了我国重要流域水体中敌敌畏的环境浓度;结合SSD模型计算了对淡水生物的潜在影响比例(potentially affected fraction,PAF)。结果表明:1)不同模型的选择会影响HC5的结果,且Burr III模型拟合结果较好,推导的HC5值为0.37μg·L-1;2)无脊椎动物在敌敌畏低浓度范围内的敏感性明显高于脊椎动物。甲壳类动物与昆虫和蜘蛛类相似,敏感度较高,鱼类则较低;3)应用Burr III模型构建SSD时,参数k值对HC5最为敏感,蒙特卡罗随机模拟得到HC5变化范围为0.05~40.57μg·L-1,均值为5.07μg·L-1;4)敌敌畏对我国淡水生态影响较小,PAF均低于1%,其中黄河和太湖流域敌敌畏的生态风险高于其他河流湖泊,珠江口和南海北部较低。上述研究结果为评价敌敌畏对全国不同水体水生生物的潜在生态风险提供了科学依据。     

多溴联苯醚在典型电子垃圾污染区域水生食物链上的生物富集特征

为调查电子垃圾回收活动对当地水生生物造成的多溴联苯醚(PBDEs)污染,测定了广东某电子垃圾回收地附近水库中水生生物样品(水蛇、鱼类、草虾和田螺)和对照区样品(鲮鱼)中18种PBDEs含量,通过对样品氮同位素的测定,探讨了PBDEs在该地淡水食物链上的生物富集特征.研究结果显示,∑PBDEs(总PBDEs含量)在水蛇、鱼类、草虾和田螺中分别为39.6～186、1.82～75.7、4.60～17.1和7.26～17.0μg·g-1(脂重),比华南地区鱼体中∑PBDEs的平均含量高3个数量级,表明电子垃圾回收活动已对当地水生生物造成了PBDEs的严重污染.除BDE66、BDE99、BDE153、BDE183和BDE209外,其他13种PBDE单体在食物链上均存在着生物放大效应,但生物放大能力(B值)与正辛醇-水分配系数logKOW相关性不明显,可能是由于某些PBDE单体在生物体内存在代谢作用.以上结果表明,由电子垃圾回收活动导致的PBDEs污染存在较大的生态风险,应该引起高度关注.     

Contribution of winter fluxes to the annual CH4, CO2 and N2O emissions from freshwater marshes in the Sanjiang Plain

Introduction C arbon dioxide, m ethane and nitrous oxide play im portant roles in the radiation balance of the earth contributing to the greenhouse effect (Rodhe, 1990). N 2O also takes part in the destruction of stratospheric ozone (W ang, 1999). N atura…     

Stratification and Tidal Current Effects on Larval Transport in the Eastern English Channel: Observations and 3D Modeling

We study how the combination of tides and freshwater buoyancy affects the marine organisms accumulation and horizontal transport in the ROFI system of the eastern English Channel. The Princeton Ocean Model coupled with a particle-tracking module is used to study the migration of fish eggs and larvae under different forcing conditions. Results of modeling are validated against observed concentrations of Flounder (Pleuronectes flesus) larvae. Numerical Lagrangian tracking experiments are performed with passive and active particles, representing sea-water organisms. Passive particles are neutrally buoyant whereas active particles are able to exercise light dependent vertical migrations equating to the swimming behavior of larvae. The experiments reveal that the strongest accumulation of particles occurs along the French coast on the margin of the ROFI. This happens because the interaction between the turbulence, the freshwater buoyancy input, and tidal dynamics, produces particle trapping and vertical spreading within the frontal convergence zone. Tides and freshwater input induce net alongshore horizontal transport toward the North. Tidal currents modulate the magnitude of horizontal transport whereas the fresh water input controls more the location of accumulation zones. Tracking experiments with active particles indicate that the vertical migration leads to a significant departure from the passive particle transport pattern. Differences lie in the shape of the particle transport pattern and the rate of the northward migration. In particular, vertically migrating particles travel slower. To find possible Flounder migration pathways, particles are released within the assumed spawning area of Flounder. The model predicts larvae drift routes and demonstrates that throughout the entire particle-tracking period the horizontal structure of the particle distribution is consistent with the larvae concentrations observed during the field experiments.     

东湖“赤潮”的成因分析及发展趋势

2003年3月下旬东湖水质发生了异常现象,为找到水质明显变化的原因,武汉市环境监测中心站通过及时布点取样分析,监测分析水中的生物群落结构,确认东湖发生了"赤潮",并找出了污染源头。通过跟踪监测,了解多甲藻的变化趋势,并提出对涉及外来物种等海洋馆类建设项目的强化管理的建议。     

模拟Fe (III)和盐水输入对闽江河口潮汐湿地沉积物及间隙水Fe和S含量和形态的影响

河口潮汐湿地沉积物电子受体和盐度的变化将对间隙水、沉积物的地球化学参数及有机碳厌氧矿化途径产生重要影响.本研究于闽江河口塔礁洲淡水野慈姑(Sagittaria trifolia L.)湿地原位施加人造海水及Fe(III)溶液,模拟研究了盐水入侵及径流Fe(III)浓度增强对河口潮汐湿地沉积物、间隙水的地球化学参数(溶解性CH4、DOC、DOC∶DON、Fe2+和ΔSO2-4)和沉积物各形态固相铁(非硫Fe(II)、无定形Fe(III)、晶质Fe(III)、Fe S和Fe S2)含量的影响.结果表明,模拟盐水入侵及径流Fe(III)浓度增强均可降低间隙水溶解性CH4和DOC浓度,径流Fe(III)浓度增强增加了非硫Fe(II)和晶质Fe(III)含量,盐水入侵可减小间隙水ΔSO2-4含量.间隙水ΔSO2-4与DOC、DOC∶DON、溶解性CH4及Fe2+浓度相关.模拟盐水入侵及径流Fe(III)浓度增强可分别促进硫酸盐异化还原和铁异化还原速率,同时减小间隙水CH4浓度,改变河口潮汐湿地土壤有机质厌氧矿化优势途径.