南四湖及主要入湖河流表层沉积物对磷酸盐的吸附特征

研究了南四湖及其主要河流人湖口18个表层沉积物对磷的吸附能力、吸附动力学及其吸附等温线,并对湖区沉积物对磷吸附特征及其理化特征之间的关系进行了探讨.结果表明,对于处于不同营养水平的沉积物,对磷酸盐的吸附具有一致的特征.在前10h沉积物对磷酸盐的吸附量基本达到或超过平衡吸附量的80%,并且在0～1.0 h内吸附反应迅速.在本研究条件下,表层沉积物的cEPC的变化范围为0.010～0.157mg·L-1, Qmax的变化范围是86.74～118.32 mg·kg-1, TQmax的变化范围是99.97～281.11 mg·kg-1·cEPC、NAP、m、Qmax和TQmax与Ads-P都具有显著的正相关关系,沉积物Ads-P含量可以作为指导南四湖水体污染程度的一项指标. m与TQmax之间具有显著的正相关性,吸附效率不仅体现的是对外来磷的吸附效率,还应当包含对本身释放磷的再吸附的效率.对于南四湖沉积物TQmax、NAP和Qmax起到同样的贡献.沉积物的NAP与cEPC之间呈显著正相关性,总的趋势就是,当上覆水中磷含量相等时,具有高的NAP的沉积物易于向上覆水体释磷,反之具有较低NAP的沉积物易从水中吸附磷.     

金山湖底泥重金属稳定化处理效果及机制研究

采用氧化钙和过氧化钙及二者混合物对底泥中的重金属进行稳定化试验,研究了稳定化后底泥中重金属迁移情况,并对底泥重金属稳定化技术的机制进行初步探讨.酸雨淋溶试验结果表明,底泥经CaO、CaO CaO2、CaO2稳定化后, pH=2.9时, Zn迁移到第3层,其首层迁移量分别为96、97和93mg/kg,而空白试验中Zn迁移至第6层,首层迁移量为128mg/kg; pH:5.0时, Zn迁移到第3层,其首层迁移量分别为87、90和89mg/kg,而空白试验中Zn迁移至第5层,首层迁移量为112mg/kg,这说明稳定化底泥中Zn的迁移速度和首层迁移量均有降低,3种稳定化药剂能够降低其在土壤中的迁移能力;淋溶液pH值对Zn的迁移能力有影响, pH较高能够减缓Zn在土壤中的迁移速度,降低其首层迁移量; Ni和Cd的酸雨淋溶试验也可得出同样结论.重金属稳定化机制试验结果表明,经上述3种药剂稳定化处理后,底泥pH值由6.76分别上升到8.33、8.15和8.21, TOC含量分别降低5%、10.9%和13.1%; Zn、Ni和Cd的稳定态含量分别增加10.6%、1.7%和4.5%,这是导致重金属迁移能力下降的主要原因;由此可见,3种药剂对同一金属的稳定化作用无明显差异;从不稳定态向稳定态转化的比例来看,稳定化药剂对不稳定态金属的稳定能力次序为: Zn>Cd>Ni.     

加拿大海盆与楚科奇海柱状沉积物中硫酸盐还原菌的分布状况

对取自北极楚科奇海及加拿大海盆的10个沉积物岩芯分别在4℃、25℃培养温度下进行硫酸盐还原菌(SRB)分析,结合首次北极科考海洋沉积物SRB的研究成果,探讨了研究区SRB的分布特点.研究结果表明,4℃与25℃温度培养的SRB含量均为0～2.4 ×106个·g-1(湿样);4℃时SRB的检出率与平均含量分别为45.5%和2.06×104个·g-1(湿样),25℃培养条件下分别为73.7%和4.70×104个·g-1(湿样);柱状沉积物中SRB的检出率、含量范围、平均含量都明显高于表层沉积物中SRB的相关指标;岩芯中SRB含量分布与采样点的纬度、深度有一定关系,但这种关系不如表层沉积物中SRB分布表现的那么明显;4℃培养时,各层位SRB含量的平均值范围为51～1.2×106个·g-1(湿样),25℃时为2.04×102～2.47×105个·g-1(湿样);在所研究的深度范围内,4℃时培养SRB的垂直变化较为明显,而25℃时SRB的垂直变化相对缓和;根据4℃、25℃2个不同培养温度时SRB的检出率、含量对比看,似乎25℃时更有利于某些SRB的繁衍.     

红枫湖沉积物中重金属污染特征与生态危害风险评价

调查了红枫湖沉积物中重金属的含量、分布特征与富集情况. 分别以现代工业化前正常颗粒沉积物中重金属含量的最高背景值和红枫湖周边环境土壤的背景值为参比值,对红枫湖沉积物中重金属的富集系数和生态危害系数以及各采样点的生态危害指数进行了探讨,并结合瑞典学者Lars Hkanson潜在生态危害指数法对红枫湖沉积物中重金属的生态危害进行了评价. 结果表明:该湖泊沉积物中重金属含量分布呈现一定的区域特征,北湖湖区重金属平均含量高于南湖湖区;以现代工业化前正常颗粒沉积物中重金属含量的最高背景值为参比值,重金属的富集顺序为Cd＞Hg＞As＞Cu＞Zn＞Pb,污染水平顺序为Cd＞Hg＞As＞Cu＞Pb＞Zn;以红枫湖周边环境土壤平均值为参比值,重金属的富集顺序为Cu＞Cd＞Zn＞As＞Pb＞Hg,污染水平顺序为Cd＞Hg＞As＞Cu＞Pb＞Zn.       

河水-地下水交互带沉积物中抗生素和代谢产物提取方法优化及其分布特征

河水-地下水交互带是污染物发生富集、降解和转化等生物地球化学过程的重要场所.抗生素作为一类广泛关注的有机污染物,探索其在交互带中的分布特征对认识特殊生境下污染物迁移转化过程具有重要意义.由于交互带氧化还原条件变化敏感,沉积物组成特殊,建立了一种有效提取交互带中22种抗生素及4种磺胺类代谢产物的前处理方法,并对样品初始状态、提取温度、提取液p H值以及有机提取溶剂进行了优化.同时对汉江下游河水-地下水交互带沉积物中的抗生素含量进行分析,结果表明,采用p H=3的乙腈/乙二胺四乙酸二钠(Na₂EDTA)-Mcllvaine缓冲液(1∶1,体积比)对未经氧化的沉积物原样在40℃条件下进行3次微波提取,目标抗生素的回收效果最好.汉江下游交互带沉积物中共检出11种抗生素,其中以土霉素(OTC)和氧氟沙星(OFL)为主,最高检出含量分别为6.77 ng·g^-1和5.81 ng·g^-1.不同交互剖面中抗生素含量的垂向分布差异较大,主要与沉积物岩性、抗生素理化性质和地表水-地下水交互作用等影响因素有关.     

Repeatability,Sensitivity, and Uncertainty Analyses of the BANCS Model Developed to Predict Annual Streambank Erosion Rates

Accelerated streambank erosion caused by channel instability can be the leading cause of sediment impairment of streams. Obtaining accurate streambank erosion rates for sediment budgeting and prioritizing mitigation efforts can be difficult and costly. One approach to quantifying streambank erosion rates is through the development and implementation of an empirically derived “Bank Assessment for Non‐point Source Consequences of Sediment” (BANCS) model. This study aims to improve the BANCS model application by evaluating repeatability between users and identifying sensitive and/or uncertain model inputs. Statistical analysis of streambank evaluations conducted by 10 different individuals suggests the implementation of the BANCS model may not be repeatable. This finding may be due to sensitive model inputs, such as streambank height and near‐bank stress level prediction method selection, and/or uncertain model inputs, such as bank material identification and the associated adjustment of erosion potential. Furthermore, it was found assessing streambanks as a group by obtaining a measure of central tendency from individual evaluations, as well as obtaining a higher level of training, may improve model implementation precision. Application of these suggestions may result in improved prediction of streambank erosion rates utilizing the BANCS model methodology.     

底泥厌氧环境和光照对菹草萌发和幼苗生理的影响

通过向底泥中投加不同量的蔗糖使其发生厌氧反应以模拟不同程度的底泥厌氧环境，研究这种环境和光照强度对菹草石芽萌发和幼苗生理作用的影响。实验结果表明，底泥厌氧环境能显著降低菹草石芽的最终萌发率，且低光照会加剧这种趋势；尽管低光照不一定会提高最终的萌发率，但对提早石芽的萌发是有利的。在01%蔗糖投加处理中，幼苗的叶绿素和可溶性蛋白含量最高(平均为250和1928 mg/g FW)，其后随投加量的升高而降低，而游离氨基酸的含量却一直呈上升趋势，最高时达到024 mg/g FW ，但低光照却使它下降；可溶性糖含量基本不受底泥厌氧水平的影响，但随着光照减少而降低。随着厌氧水平的增加（从对照到05%蔗糖投加量），菹草的超氧物歧化酶(SOD)活性呈现上升趋势，但在10%蔗糖投加处理中活性降至最低；而过氧化物酶(POD)活性一直处于下降趋势。研究结论是：底泥厌氧对菹草石芽萌发影响显著，这种影响可能比低光照的限制作用还要重要。轻度的厌氧环境反而能促进菹草幼苗的生理代谢，但随厌氧水平的升高对碳氮平衡和其它生理活动产生不利影响。此外，底泥厌氧环境对菹草幼苗的抗氧化系统也有明显刺激作用。     

Trophic state, ecosystem efficiency and biodiversity of transitional aquatic ecosystems: analysis of environmental quality based on different benthic indicators

Estuaries and coastal lagoons are characterized by a strong spatial and temporal variability of physicochemical characteristics and productivity patterns. In these environments, the magnitude and direction of the ecological responses to inorganic nutrient increase (i.e. eutrophication) are difficult to predict. In the framework of the project, New Indicators of Trophic state and environmental quality of marine coastal ecosystems and transitional environments (NITIDA), we analysed benthic indicators of trophic state, ecosystem efficiency, and environmental quality in four different transitional environments. The trophic state of the sediments was assessed in terms of quantity and bioavailability of sediment organic C pools; ecosystem efficiency was determined in terms of the prokaryote efficiency in exploiting enzymatycally degraded organic C; environmental quality was determined in terms of meiofaunal diversity. Here, we provide a synopsis of the results obtained and a meta-analysis of the scores assessments obtained using the different ecological indicators of environmental quality and demonstrate that trophic state, ecosystem efficiency, and biodiversity in transitional ecosystems are closely linked. We conclude that the assessment of the environmental quality of transitional ecosystems should be based upon a battery of trophic state indicators and 'sensors' of ecosystem functioning, efficiency, and quality.     

TRACE METALS IN SEDIMENT: SPATIAL TRENDS AND SORPTION PROCESSES1

ABSTRACT: Sediment bound trace metals are often examined for spatial trends such as downstream patterns or distance from a source. Spatial trends may indicate either differences in metal inputs, or, when considerable sediment variability exists, differences in sediment sorption processes. These two possibilities become important not only when sediment contamination is evaluated within an area, but also when regulatory agencies attempt to make equivalent among area decisions. Sediments from an urban watershed were examined for: (1) downstream trace metal trends and (2) sediment sorption relationships. Analyses determined that downstream trenda as related to metal inputs could not be recognized by analyzing the < 2mm (≤, sand) sediment size fraction. Conversely, the trace metal concentrations were found to be distinctly related to sediment characteristics. The watershed's metal concentrations are similar to those found in uncontaminated to slightly contaminated sediments in the United States.     

HYDROLOGIC EFFECTS OF TWO METHODS OF HARVESTING MATURE SOUTHERN PINE1

ABSTRACT: Hydrologic responses to logging with skidders and responses to logging with a cable yarder are compared. After a 23-year calibration with an undisturbed control catchment, mixed stands of shortleaf pine (Pinus echinata Mill.) and hardwoods were clearfelled on two small catchments in the hilly Coastal Plain of north Mississippi and observed for five years. Runoff increased 370 mm (skidded) and 116 mm (yarded) during the first year with 1876 mm of rainfall, and 234 mm (skidded) and 228 mm (yarded) during the second year when 1388 mm of precipitation equaled the calibration mean. Sediment concentrations for the yarded catchment during the first two years averaged 641 and 1,629 mg L^?1, respectively, and yields were 6,502 and 12,086 kg ha^?1. Compared to calibration means of 74 mg L^?1 and 142 kg ha^?1, these extreme values can be attributed largely to transport of sediment stored in the channel and to erosion of subsurface flow paths, which was exacerbated by high flow volumes. During the first year, the concentration (231 mg L^?1) and yield (2,827 kg ha^?1) for the control catchment also exceeded the calibration means. However, concentrations (134 mg L^?1) and yields (1,806 kg ha^?1) for the skidded catchment were about 40 percent lower than for the control catchment during the first year, and were higher than those for the control only during the second year. Because deep percolation was limited and because rainfall was unusually high, increases in flows and sediment concentrations and yields probably approximate maximum responses to clearcut harvesting in the uplands of the southern Coastal Plain.