The role of organic matter in the sorption capacity of marine sediments

Past studies have suggested that desiccation enhances hydrophobicity of salt marsh sediment, and that drying and rewetting sediment can be used to investigate sorption mechanisms of amino acids and other organic compounds [Liu, Z., Lee, C., 2006. Drying effects on sorption capacity of coastal sediment: The importance of architecture and polarity of organic matter. Geochim. Cosmochim. Acta 70, 3313–3324]. Here we further develop this technique to study sorption of hydrophobic and hydrophilic organic compounds in a wide range of marine sediments. Our results show that hydrophilic compounds sorb strongly to wet coastal sediments; in dried sediments, sorption of hydrophilic compounds decreases, while sorption of hydrophobic compounds is greatly enhanced. Small compounds with aromatic rings sorb more in dried than wet coastal sediments, suggesting that aromatic groups have a stronger effect on sorption than polar groups like amino and carboxyl moieties. Sorption of lysine, glutamic acid and putrescine decreases greatly when sediment is pretreated with KCl, indicating the importance of cation ion exchange. However, α-amino acids sorb much more than corresponding β- or γ-amino acids, and l-alanine sorbs more than d-alanine, suggesting that amino group location and chiral selectivity play an important role in sorption. Comparison of lysine and tyrosine sorption in different sediments indicates that source and diagenetic state of organic matter are important factors determining sorption capacity. Lysine sorbs much more to organic detritus from salt marsh sediment than to fresh Spartina root materials, marine particles, lignin or humic acids, indicating the importance of structural integrity in sorption. Desorption hysteresis of glutamic acid, putrescine and lysine (in dried sediment) suggests the presence of enzyme-type sorption sites of high sorption energy or multiple binding mechanisms. Taken together, these findings suggest that organic matter plays the major role in amino acid sorption in organic-rich sediments.     

Characteristics of Oil Contamination and Numerical Modelling of Its Transport in Fracture-Karst Water in Zibo City,China

In this paper, the hydraulic characteristics of the fracture-karst aquifer and the distribution patterns of petrochemical contaminants are studied. Then, a numerical model using the mixed Eulerian-Lagrangian approach is constructed to predict the distribution and transport of petrochemical compounds in groundwater. The results of numerical modelling and sensitivity analysis show that it may be a workable way for aquifer remediation to combine contamination sources control and capture zone establishment.     

The impacts of pasture- and manure-spreading on microbial groundwater quality in carbonate aquifers

Hydrogeological and microbiological research is in progress to analyze the interaction between groundwater and microbial pollutants, produced by pasture and/or manure spreading, in the areas of different carbonate aquifers of southern Italy. Several springs and wells were studied, and the precipitation, the discharge, the groundwater level and the classic microbial indicators of pollution were monitored weekly or daily. The experimental results show that the pasture and the manure spreading produced microbial contamination of the groundwater, even if runoff infiltration in swallow holes does not exist. The time dependence of microbial contamination shows a series of peaks irregularly distributed, related to the precipitation that produce effective infiltration.     

Uptake and depuration of PAHs and chlorinated pesticides by semi-permeable membrane devices (SPMDs) and green-lipped mussels (Perna viridis)

Semi-batch seawater experiments were conducted to follow the uptake and release of selected PAHs (anthracene, fluorathene, pyrene and B[a]P) and organochlorine pesticides (α-HCH, aldrin, dieldrin, p,p′-DDT) in semi-permeable membrane devices (SPMDs) and green-lipped mussels (Perna viridis). Mathematical models were applied to describe the uptake and elimination curves of the contaminants for SPMDs, and kinetic parameters, such as uptake rate constants, and equilibrium triolein/water partitioning coefficients were calculated. SPMD data showed a good fit to estimate rate constant and partition coefficient equations, but only those contaminants which partitioned mainly in the dissolved phase (α-HCH and dieldrin) were well explained for mussels. Poor conformity of the other contaminants indicated mussels uptake by routes other than diffusion, such as ingestion of algae. An apparent equilibrium state was only noted for α-HCH in mussels. Aldrin was not detected in mussels in the first few days of exposure, indicating potential metabolism of this compound. B[a]P was not detected in the triolein of SPMDs, which suggests that the membrane may act as a reservoir. Loss of spiked B[a]P from the triolein was evident in a depuration experiment, which may indicate transfer to the membrane. Rate constants for mussels were higher than those for SPMDs, but the reverse was true for partition coefficients. Overall, mussels and SPMDs had similar uptake rates for all compounds in this study, excluding p,p′-DDT and dieldrin. Contaminant elimination took place more rapidly in mussels, implying that SPMDs are better candidates for detecting episodic discharge of organic contaminants.     

煤矸石浸泡污染物溶解释放规律研究--阜新市新邱露天煤矿不同风化煤矸石在不同固液比条件下浸泡实验

论文对新邱露天矿不同风化程度的煤矸石在不同固液比条件下溶解释放污染物的规律进行了浸泡实验研究。结果表明:煤矸石溶解释放的主要污染物为总硬度(CaCO3)、硫酸盐(SO42-)、钠(Na )、总溶解性固体(TDS)、氟化物(F-)、耗氧量(OC)和总铁(Fe)等,氯化物(Cl-)、锰(Mn)、锌(Zn)等少量,其它重金属和砷等微量。pH值接近中性。煤矸石风化程度越高,溶解释放的无机盐类污染物量越多,新鲜混合煤矸石溶解释放出较高的氟化物(F-)、耗氧量(OC)和总铁(Fe);固液比对煤矸石中污染物的溶解释放有重要影响。固液比越小,浸泡液中污染物浓度越低,越有利于煤矸石中污染物的溶解释放,单位质量煤矸石溶解释放的污染物量越多,煤矸石中污染物的溶解释放规律受扩散控制;在同一固液比条件下,各污染物浓度变化与浸泡时间成对数曲线关系,即Ct=a bLogt。     

90年代发展中国家国际资本流入的新特点及其影响

从1992年起,流向发展中国家的证券资本以较大的优势超过了国际直接投资。在全球经济一体化、金融市场自由化和国际化的背景下,国际资本跨国流动呈现出规模巨大化、运作方式机构化、流动形式多样化的特点。庞大证券资本的注入在给新兴市场国家带来益处的同时,也可能造成伤害,这一点在墨西哥和东南亚金融危机中已经得到证实。因此防范和化解国际资本的流入所带来的金融风险,是新兴市场国家当前所面临的严峻课题。     

Cd, Cr, Cu, Ni and Pb in the water column and sediments of the Ob-Irtysh Rivers, Russia

Concentrations of Cd, Cr, Cu, Ni and Pb were determined in filtered water, suspended particulate matter, and bottom sediments from a 2000 km section of the Ob and Irtysh Rivers. Dissolved Cd, Cr, Cu and Ni concentrations are similar to, or higher than, results from other Russian Arctic and large world river-estuaries. Concentrations of Cd, Cr, Cu, Ni and Pb in suspended particulate matter are generally comparable to results from other Russian Arctic and large world rivers and estuaries. Comparison of trace metal ratios in crustal material and suspended particulate matter and bottom sediment suggests that the source of Cr, Cu and Ni is continental weathering. Particulate Cd and Pb are elevated relative to their crustal abundance, suggesting a source of these metals to the Ob-Irtysh in addition to continental weathering.     

高密度蓝藻厌氧分解过程与污染物释放实验研究

采用批次培养实验模拟高密度蓝藻堆积发生的厌氧分解过程,分析蓝藻的分解速率及污染物释放规律.厌氧分解实验中,设置三组蓝藻初始密度分别为2.23×1012、1.19×1013、4.47×1013cells/L,得到叶绿素a的分解速率常数分别为0.074、0.133、0.081 d-1.蓝藻厌氧分解过程中水体呈酸性,电导率呈上升趋势,最高值为949μS/cm.化学需氧量持续升高,而UV254值先升高后降低,说明水体中有机物浓度增大,并逐渐由大分子分解为小分子有机物.蓝藻厌氧分解释放出大量溶解态氮、磷,溶解态有机氮逐渐被降解为无机氮,铵态氮含量占90%以上.研究表明,高密度蓝藻堆积发生厌氧分解可释放大量有机物和溶解态营养盐至水体中,并且随着蓝藻密度升高,污染物释放强度增大.因此水华期间应及时打捞蓝藻,以避免蓝藻大量堆积死亡导致水源区水质下降并影响自来水出水质量.     

Emerging organic contaminants (EOCs) in freshwaters in Dunedin,New Zealand

Emerging organic contaminants (EOCs) in New Zealand freshwaters are not well documented for regulatory assessments. We collected water and sediment samples for measurement of 26 EOC compound concentrations at four waterways within the city of Dunedin (Otago province). Compounds measured ranged from stimulants and depressants to pain-killers and insect repellants. Sampling was conducted before and after the student ‘Orientation Week’ at the University of Otago. Most compounds were below detection limits in all samples. However, caffeine, carbamazepine, cotinine and DEET were all measured at concentrations above detection limits. In general, concentrations of EOC compounds were ～20% higher following the influx of students to the University though student effects varied by site and additional sampling is needed to better assess temporal variation in concentrations. These data indicate that some EOCs are present in New Zealand freshwater ecosystems.     

随机波浪下斯托克司漂移速度是否引起水面漂移物离散的研究

漂浮于自由水面的污染物的的迁移、扩散会受到天然随机海浪的影响。之前的研究（以Herterich和Hasselmann（1982）为代表）普遍认为,随机波浪作用下的斯托克司漂移速度会引起水面污染物的离散,这个离散甚至有可能跟风和海流引起的离散同一量级。本研究就随机波浪作用下的斯托克司漂移速度是否会引起水面漂移物的离散进行理论和试验探讨。从理论推导可知,随机波浪下的质量输移速度是个定常分量,因此它不会随时间变化而引起水面漂移物的离散。随后我们在实验室水槽中进行了漂移物在随机波浪（P-M谱）作用下的漂移过程的测量。试验结果也印证了随机波浪作用下的斯托克司漂移速度不会引起水面漂移物离散的结论。