"南水北调"中线水源区可利用降水量时序分析——以十堰市为例

可利用降水量的盈亏程度对于"南水北调"输水工程水源区和受水区的水资源、水环境和社会发展具有重要意义.基于4个气象站逐日数据计算地处"南水北调"水源区的十堰市1980～2019年可利用降水量,并利用Mann-Kendall方法和小波分析探讨40年间可利用降水量变化特点.研究表明:受十堰市40年间降水量减少和潜在蒸散发增多的影响,可利用降水量呈减少趋势,变化倾向率为42.796 mm/1Oa;年均和各季节可利用降水量均发生过突变,年可利用降水量突变发生在1991年前后;十堰市全年和各季节可利用降水量的显著变化周期均在5年以内.十堰市可利用降水资源日趋紧张,应充分利用好客水资源,提高水资源利用效率,保障"南水北调"输水工程平稳运行.     

五氯酚(PCP)对鸡肝癌细胞(LMH)毒性效应的机制研究

五氯酚(pentachlorophenol,PCP)是一种持久性有机污染物,广泛用于灭钉螺、木材防腐、除草剂等方面,由于PCP在环境中的持久性和生物累积性,其对生态环境和人类健康造成潜在危害。本文以鸡肝癌细胞系(chicken hepatoma cells,LMH)为受试对象,探讨了PCP对细胞色素P450(CYP450)和抗氧化系统的影响。MTT结果显示LMH细胞经不同浓度PCP暴露后,呈现出先促进细胞增殖后抑制的J-型曲线,PCP对LMH细胞24 h的半数效应浓度(24 h-EC50)为427.52μmol·L~(-1)。LMH细胞在1.56、6.25、25、100μmol·L~(-1)PCP染毒条件下可增加细胞EROD、MROD、PROD和BFC活性,并可使CYP1A、1B、1C、2H及3A家族基因mRNA表达水平升高。LMH细胞在0.4~100μmol·L~(-1)PCP染毒下可显著降低硫酸基转移酶(SULT1B1和SULT 1C1)基因mRNA水平。此外,LMH细胞在6.25、25、100μmol·L~(-1)PCP染毒下可引起细胞内ROS升高,同时PCP(1.56~100μmol·L~(-1))可显著增加细胞内MDA含量和降低GSH/GSSH比值。这些结果表明细胞色素P450(CYP450)基因及酶活性的变化、细胞内ROS和MDA含量及GSH/GSSH可作为评价LMH细胞PCP毒性效应的敏感性生物标志物。此研究在细胞水平上利用多个评价指标研究PCP对细胞的毒性效应,为PCP环境风险评价提供依据。     

The effect of municipal sludge compost on the mobility and bioavailability of Cd in a sierozem-wheat system in an arid region northwest of China

The effect of sewage sludge on the mobility and the bioavailability of trace metals in plant-soil systems have aroused wide interested and been widely explored. Based on a wheat-cultivating experiment, the effect of municipal sludge compost (MSC) on the mobility and bioavailability of Cd in a soil-wheat system was studied. With the application of MSC, soil organic matter (SOM), total nitrogen (TN), and total phosphorus (TP) in the soil increased significantly, while concentrations of trace metals (Cu, Zn, Ni, Pb, Cd) were below the China’s minimum thresholds. The application of MSC could improve wheat growth. The application of MSC at the rate of 0.5 % had no significant effect on the chemical fraction distribution of Cd in soil. In two soil treatments, Cd mainly existed in the labile chemical fractions (exchangeable chemical fraction (EXCF) and carbonate chemical fraction (CABF)). However, the application of MSC could reduce accumulation of Cd by wheat. Cd contents in each part of the MSC-applied wheat were significantly less than that of non-MSC-applied wheat. In the tested soils, the extractable concentrations decreased in the order: EDTA > MgCl₂ ≈ NH₄OAc > DTPA. There were no significant differences between soil treatments in the amounts of extractable Cd when the extraction was done under neutral conditions, although significant differences were observed when the extraction was done under alkaline conditions. In this study, the DTPA extraction procedure provided a good indication of Cd bioavailability. Our results suggest that, in the short term at least, amending soils with MSC may benefit crop dry matter production while not increasing the risk of human exposure to Cd through consumption of wheat grown on MSC-amended soils.     

Experimental studies and kinetic modeling of the growth of phenol-degrading bacteria in turbulent fluids

Understanding the interaction between microorganisms and fluid dynamics is important for aquatic ecosystems, though only sporadic attention has been focused on this topic in the past. In this study, particular attention was paid to the phenol-degrading bacterial strains Microbacterium oxydans LY1 and Alcaligenes faecalis LY2 subjected to controlled fluid flow under laboratory conditions. These two strains were found to be able to degrade phenols over a concentration range from 50 to 500 mg/L under different turbulence conditions ranging from 0 to 250 rpm. The time it took to reach total phenol degradation decreased when the turbulence was increased in both strains, with increasing energy dissipation rates ranging from 0.110 to 6.241 W/kg, corresponding to changes in the bacterial diffusive sublayer thickness (δ) and enhanced oxygen uptake. Moreover, the maximum specific growth rates of the two strains also increased with the enhancement of turbulence. A model integrating growth inhibition and fluid motion was proposed based on the self-inhibition Haldane model by introducing a turbulence parameter, α. The resulting modified Haldane model was designed to include fluid motion as a variable in the quantification of the physiological responses of microorganisms. This modified Haldane model could be considered a useful laboratory reference when modeling procedures for water environment bioremediation.

Cell nutrition uptake cartoon schematic diagram for M. oxydans LY1 under different turbulent condition (50 and 200 rpm).

     

浅析成都市机动车保有量的增加对大气污染物中二氧化氮浓度的影响

本文利用成都市城区近4年的环境空气二氧化氮浓度资料,结合成都市机动车保有量,分析了成都市机动车保有量的增加对空气中二氧化氮浓度的影响。分析表明,成都市机动车保有量的增加对空气中二氧化氮浓度有明显影响,尤以交通干道附近最为显著,二氧化氮浓度较非交通干线分别偏高12.0%～47.8%,成都市采取的高污染车限行等措施对二氧化氮浓度的控制起了重要作用。     

黑龙江省经济空间结构变动及影响因素研究

经济空间结构是经济地理学和区域经济学研究的重要议题之一。利用1995年以来县域统计资料对黑龙江省经济空间结构演变进行了研究。结果表明：①空间分化显著;②极不发达县域向东扩展;③区域发展绝对差距扩大,相对差距先增后减;④中心城市发展缓慢,但哈尔滨、大庆、牡丹江三市的带动作用显著。探讨了经济空间结构变化的因素,历史基础与路径依赖、经济发展政策、区位、交通条件和自然资源是导致黑龙江经济空间结构演变的影响因素。     

山仔水库典型样地次降雨径流过程磷流失特征研究

降雨径流是农业非点源污染发生的主要动力.福州第二饮用水源地山仔水库是周边以农业用地为主的峡谷型水库,由降雨径流输入库区的农业非点源污染不容忽视,而磷污染是引起水体富营养化最关键的限制因子.选取山仔水库库区典型样地松竹林、水稻田和地瓜地为研究对象,同步监测4次降雨径流过程径流量、总磷和可溶性磷浓度,对次降雨产流和磷输出特征以及两者的相关性进行了研究.结果表明,径流量峰值滞后于降雨量峰值约20 min,样地按径流量从大到小排序为松竹林、水稻田、地瓜地;土壤中大部分的磷以颗粒态形式流失,地瓜地、水稻田和竹林在4次降雨径流过程输出总磷的平均质量浓度分别为0.145 1 mg/L、0.124 3 mg/L、0.097 0 mg/L,可溶性磷的平均质量浓度分别为0.036 9 mg/L、0.031 3 mg/L、0.022 8 mg/L;松竹林、水稻田、地瓜地的总磷输出负荷与降雨径流量之间存在典型的多项式正相关关系,其相关系数分别为0.998 2、0.997 8、0.998 4.     

基于改进型扩散函数内集-外集模型的辽宁省旱灾风险评价

采用改进的基于扩散函数的内集-外集模型,分析1949-2007年辽宁省旱灾受灾指数,评价辽宁省的旱灾风险.结果表明,辽宁省旱灾发生频繁,平均每1.7 a一遇且严重干旱多发,这与辽宁省旱灾的实际情况基本吻合.研究表明,内集-外集模型计算结果的意义清楚,对防灾减灾有一定指导作用.     

辽宁省降水日数的气候变化特征

利用均匀分布在辽宁省39个测站1961-2005年的逐日降水量资料,分析了近45a来辽宁省年、季、月降水日数,及连续降水日数和连续无降水日数的长期变化趋势以及空间分布状况.结果表明,近45a来辽宁省年降水日数是明显减少的,平均每10a减少1.8d,显著减少的区域在辽东半岛和部分沿海地区,显著减少的季节是夏季;连续降水日数在雨季以负趋势为主,而连续无降水日数则以正趋势为主,在辽河平原的西部以及辽西山区的大部两者趋势都很明显,说明这些地区干旱出现的几率在增大.