基于改进萤火虫算法的投影寻踪太湖水质综合评价

针对水质评价中指标的多样性及不相容性,提出了基于改进的萤火虫算法的投影寻踪水质评价方法。该方法根据水质标准等级样本集所划分的标准,构建投影指标函数,并用改进的萤火虫算法进行优化,使搜索步长逐步减小,寻优后期也可具有良好的局部搜索能力,得到最佳投影方向,使综合评价结果能够客观准确地反映出水质状况。运用该方法对太湖的水质数据进行综合评价,并与传统方法综合评分法(F值法)得到的结果进行对比,评价结果更符合当地水质状况实际情况,且对水质等级划分更为清晰。     

南太湖近岸水域叶绿素a含量与氮磷浓度的关系

2007年6月-2008年4月对南太湖近岸水域进行了4次生态环境调查,在此基础上,对叶绿素a含量（Chl.a）与总氮（TN）、总磷（TP）浓度及氮磷比（N/P）的关系进行了统计分析。结果表明：南太湖水体中Chl.a含量与TN浓度的关系存在显著的季节差异,在蓝藻水华大范围爆发的2007年6月和2008年4月2者呈极显著的正相关,而2007年10月和2008年1月2者无显著性关系;Chl.a含量与TP浓度在4次调查中皆无显著相关关系;岭回归分析显示,N/P 10～25是南太湖水体中附着藻类的最佳生长范围,此时总氮、总磷浓度及氮磷比与Chl.a含量呈显著的正相关,4者的多元回归关系为Chl.a=-0.0012＋0.0064 TN＋0.0215 TP＋0.0005N/P（R=0.543,P〈0.023）。总体来说,南太湖水体中的总氮、总磷浓度及氮磷比皆在藻类生长的适宜范围内,氮磷浓度处于较高水平,已经不是藻类生长的限制因素,在不同水温、光照等环境因子的作用下,加上本水域复杂的水文和季风共同影响下形成了蓝藻水华爆发的季节性差异。     

滨水环境景观设计研究——以湖州太湖旅游度假区为例

湖州市是一座江南古城,有着浓厚的文化底蕴.湖州太湖旅游度假区位于湖州市境内,其区域内河道网络纵横交错,产生了众多的桥梁和滨水地带.为进一步提升湖州滨湖度假区环境品质,增加度假休闲氛围,打造国内一流休闲旅游度假区,现对滨湖休闲景现带的景观设计理念进行研究探讨.     

太湖地区地表水氮污染源的评论

The nitrogen （N） pollution status of the 12 most important rivers in Changshu, Taihu Lake region was investigated. Water samples were collected from depths of 0.5-1.0 m with the aid of the global positioning system （GPS）. The seasonal variations in the concentrations of different N components in the rivers were measured. Using tension-free monolith lysimeters and ^15N-labeled fertilizer, field experiments were carried out in this region to determine variations of iSN abundance of NO3^- in the leachate during the rice and wheat growing seasons, respectively. Results showed that the main source of N pollution of surface waters in the Taihu Lake region was not the N fertilizer applied in the farmland but the urban domestic sewage and rural human and animal excreta directly discharged into the water bodies without treatment. Atmospheric dry and wet N deposition was another evident source of N pollutant of the surface waters. In conclusion, it would not be correct to attribute the N applied to farmlands as the source of N pollution of the surface waters in this region.     

环太湖耕地利用变化与驱动机制研究——以苏州市吴中区为例

以环太湖苏州市吴中区为样区,利用统计资料、遥感数据和典型调查数据,结合RS和GIS技术,分析18年来耕地利用变化特点与驱动机制。结果表明:研究区耕地年递减率为1.6%,表现出以水域和各类非农建设用地大量占用耕地为突出特点的区域土地动态变化特征;耕地数量变化与区位和地形有关;种植业对耕地利用强度出现波动下降趋势,作物生产由粮食作物生产为主转化为粮食与经济作物生产并重;其变化机制主要是经济发展、人口增长、农业结构调整和政策因素驱动。最后,并在此基础上提出相关建议。     

近20年太湖流域典型区土壤养分时空变化及驱动机理

长期的定位采样试验研究了近 2 0年锡山市甘露乡土壤表层 ( 0～ 2 0cm)中有机质、全氮、速效氮、速效磷、速效钾等土壤养分的时空变化趋势 ,并分析了土壤养分波动与国家政策、耕作方式、农业投入和单位面积农业纯收益之间的相互关系。结果表明 :2 0年间土壤养分质量总体上呈现先减后增的变化趋势。有机质呈现先减后增的变化趋势 ,且与耕作措施的改变有密切关系。全氮和速效氮呈持续上升趋势 ,上升幅度大于 1 0 0 % ,与氮肥使用量不断上升密切相关。速效磷、速效钾呈持续下降趋势 ,与磷肥、钾肥使用过少有关。国家政策和耕作方式、种植制度对SNQI影响十分明显 ,标准农业投入与土壤养分质量指数呈正相关关系 ,单位面积标准农业纯收益与土壤养分质量指数呈负相关关系     

Partitioning characteristics of PAHs between sediment and water in a shallow lake

Goal, Scope and Background

Distribution of hydrophobic organic contaminants in abiotic compartments is essential for describing their transfer and fate in aquatic ecosystems. Taihu Lake is the third largest freshwater lake in China. Water quality of Taihu Lake has deteriorated greatly during the last decades and has threatened the water supply. The aim of the present study was to investigate the partitioning of polycyclic aromatic hydrocarbons (PAHs) among overlying water, suspended particulate matter (SPM), sediments, and pore water in Meiliang Bay, Taihu Lake and to provide useful information for the ecological engineering in this area.

Materials and Methods

Overlying water and surface sediment were sampled from six sites in Meiliang Bay, Taihu Lake, China. Within 72 h of sampling, sediments were centrifuged to obtain the pore water. Overlying water samples were filtered to separate dissolved and SPM samples. After extraction, samples were purified following a clean-up procedure. PAH fraction was obtained by elution with a mixture of hexane: DCM (7:3, V/V) and analyzed by GC/MS.

Results

PAHs concentrations in overlying water varied from 37.5 ng/L to 183.5 ng/L. Concentrations of PAHs in pore water were higher than those in overlying water. The total concentrations of 16 priority PAHs in sediments ranged from 2091.8 ng/g-dw to 4094.4 ng/g-dw. PAHs concentrations on SPM were decreased with suspended solid concentrations (SSC). Total PAHs concentrations on SPM varied in the range of 3369.6 ng/g-dw to 7531.1 ng/g-dw. The partition coefficients between sediment and overlying water (log K _oc) for PAHs with log K _ow<5 were positively correlated with their octanol-water partition coefficients (log K _ow) (n=39, r=0.79, p<0.0001). Partition coefficients between sediment and pore water (log K _oc′) for all PAHs were also significantly correlated with their log K _ow values (n=48, r=0.82, p<0.0001).

Discussion

In general, PAHs derived from combustion sources tend to bind strongly to soot particles in natural sediment. Consequentially, K _oc values observed in the natural environment could be orders of magnitude higher than those predicted by linear correlation relationships under laboratory conditions. In the present study, the ratio of log K _oc values to log K _ow values falls consistently above 1, indicating that the sediment soot carbon in the bay was more attractive for PAHs than n-octanol. The log K _oc′ was also higher than that predicted under laboratory conditions, suggesting that the measured pore water PAH concentrations were lower than those predicted. That is to say, not all the sediment PAHs can be available to partition rapidly into sediment pore waters. A variation in soot content is a possible reason. Furthermore, concentrations of PAHs on SPM were higher than those in sediments. The compositions of PAHs on SPM and in sediments were similar, indicating the importance of re-suspension process of sediments in the partitioning process of the shallow lake.

Conclusions

The results indicated the equilibrium partitioning model could be used to predict PAHs distribution in various phases of a shallow lake in the stagnation period, but re-suspension processes should be considered to modify the relationship between log K _ocs and log K _ows.

Recommendations and Perspectives

Concentration, particle size and composition of resuspended particles could affect the relationship between log K _ocs and log K _ows. Further work should be done under field conditions, especially where a steady thermodynamic equilibrium state could be assumed.

     

淹水时间对水稻土磷素形态转化及其有效性的影响

水稻土淹水后土壤中P的形态及其有效性发生了变化,为掌握淹水时间对这种变化影响的规律,选择太湖地区典型水稻土-黄泥土为试验样本,在室内进行了不同淹水时间的土壤培育试验,并采用新鲜土壤样品测定的方法,研究了淹水时间对土壤P素形态转化及其有效性的影响.结果表明:①淹水时间主要影响Fe-P、O-P、Ca10-P和Ca8-P的转化.与淹水前相比,淹水使Fe-P和Ca8-P增加、O-P和Ca10-P减少,其中,Fe-P和Ca8-P分别于淹水45和15天后增加最为显著并趋于稳定,此时分别增加了194和9.6 mg/kg(分别占淹水前的93％和73％);O-P和Ca10-P于淹水15天后减少最为显著并趋于稳定,此时分别减少了72和20 mg/kg(分别占淹水前的24％和27％):②淹水改变了水稻土P素有效性及有效P的数量,与淹水前相比,淹水45天,水稻土 P素有效性及有效P的数量最高,有效P增加了32 mg/kg(占淹水前的57％).结论:淹水时间影响着水稻土 P素形态转化、有效性以及有效P的数量,淹水45天,水稻土P素形态转化数量最大、有效性最高和有效P的数量最大.     

长期施用化肥和秸秆对水稻土碳氮矿化的影响

以长期定位试验的土壤为供试材料,通过室内培养试验,研究了长期施用化肥和秸秆对水稻土?C、N矿化和微生物生物量的影响。结果表明长期施用化肥和秸秆增加了土壤?C?矿化量,但降低了可矿化?C?在土壤有机?C?中的比例。长期施用化肥能够增加土壤?N?矿化量,而且增加了可矿化?N?在土壤全?N?中的比例,但配施秸秆不能继续增加?N?矿化量。长期施用化肥和秸秆能够显著增加土壤微生物生物量?C、N?含量,但微生物量在土壤中的比例变化不大。     

体细胞克隆太湖猪出生

以中国太湖猪胎儿成纤维细胞为核供体,以体外成熟卵母细胞为核受体,以杜洛克猪为代孕母猪,进行了太湖猪体细胞克隆技术的研究,成功地获得了首例体细胞克隆太湖猪仔猪.经微卫星DNA多态性鉴定,确定克隆猪来自供核细胞,与代孕母猪无亲缘关系.本研究将为体细胞克隆技术在我国太湖猪育种、建立人类疾病模型等研究方面提供可行的技术方法.