Interactions between arbuscular mycorrhizae and heavy metals under sand culture experiment

A sand culture experiment was established to determine interactions between arbuscular mycorrhizae and heavy metals. Mycorrhizal infection rates, spore densities, maize root and shoot weights, and heavy metal contents in maize were as indexes of responses of arbuscular mycorrhizal fungi (Acaulospora laevis, Glomus caledonium and Glomus manihotis) to heavy metals (Cu and Cd). The mycorrhizal infection rates of G. caledonium were the highest among these three mycorrhizal fungi, but the sporulating ability of G. caledonium was the poorest in the heavy metal treatments. The shoot and root weights of non-mycorrhizal plants were usually greater than those of mycorrhizal plants when the Cu concentrations in solutions are less than 3 mg l(-1) or Cd concentrations less than 1 mg l(-1). When Cd concentrations were 0.5 and 1 mg(-1), the root and shoot weights of plants inoculated with A. laevis were significantly (p < 0.05) lower than those of other treatments. Copper concentrations in shoots of mycorrhizal plants were higher than those of non-mycorrhizal ones at all Cu concentrations in solution, especially at low Cu concentrations. As to A. laevis, Cu concentrations in roots and shoots of the host were higher than those of non-mycorrhizal plants in these treatments. Thus A. laevis was sensitive to Cu and Cd, especially Cd, and G. caledonium was more tolerant to these two heavy metals. It is suggested that G. caledonium might be a promising mycorrhizal fungus for bioremediation of heavy metal contaminated soil.     

乐安江水和沉积物样品的生物毒性评估

采用二种发光菌发光抑制、二种藻生长抑制、大型溲生和慢性毒性多种生物测试方法。对采集于１９９３年６月，１９９３年１２月和１９９４１０月的乐安江可水、沉积物和沉积物间隙不进行了多指标生物毒性测试，在河流４０，５０和１５９ｋｍ处观测到较强毒性，研究结果：毒性排放主要来自乐安江上游德兴铜矿、洎不河，以及乐安江下游接近鄱阳湖口和沉积物中重金属的释放。     

Alkaline phosphatase activity in marine macrophytes: histochemical localization in some widespread species in southern Spain

Alkaline phosphatase activity (APA) was determined in 44 species of marine macrophytes collected throughout 1991 and 1992 along the southern coast of Spain. Activity varied between 0.83 mol paranitrophenol (pNP) released g^-1 dry wt h^-1 in Ulva rigida var. gigantea and 238.8 mol pNP g^-1 dry wt h^-1 in Bangia fuscopurpurea. Using a histochemical method, APA sites were located in five of these species: Corallina elongata Ellis et Soland, Gelidium latifolium (Grev.) Thur. et Born., G. sesquipedale (Clem.) Born. et Thur., Porphyra umbilicalis (L.) Kützing and Zostera noltii Hornem. Enzymatic activity was found in the outer part of the thallus, either on the cell wall or in the cortical cells. In the marine phanerogam Z. noltii activity was also located in the vascular bundle. The results suggest that APA is present in many, if not all, marine macrophytes from southern Spain, and plays a relevant role in the utilization of dissolved organic phosphorus compounds.     

Quantification and index of non-point source pollution in Taihu Lake region with GIS

The contribution of phosphorus and nitrogen from non-point source pollution (NPS) in the Taihu Lake region was investigated through case study and surveying in the town of Xueyan, From experimental results coupled with survey and statistics in the studied area, the distribution of nitrogen and phosphorus input to the water body is achieved from four main sources: agricultural land, village, the town center and the poultry factory. The results showed that about 38% of total phosphorus (TP) and 48% of total nitrogen (TN) discharged is from agricultural land, 33% of TP and 40% TN from village residents, 25% of TP and 10% of TN from the town center and 4% of TP and 2% of TN from the poultry factory. The Agricultural Non-point Pollution Potential Index (APPI) system for identifying and ranking critical areas of NPS was established with a Geographic Information Systems (GIS)-based technology. Quantification of the key factors in non-point sources pollution was carried out utilizing the following: Sediment Production Index (SPI), Runoff Index (RI), People and Animal Loading Index (PALI) and Chemical Use Index (CUI). These are the core parts of the model, and the weighting factor of each index was evaluated according the results of quantification. The model was successfully applied for evaluating APPI in Xueyan. Results from the model showed that the critical area identified for NPS control in Xueyan. The model has several advantages including: requiring fewer parameters, easy acquirement of these parameters, friendly interface, and convenience of operation. In addition it is especially useful for identifying critical areas of NPS when the basic data are not fully accessible, which is the present situation in China.     

Effects of cadmium on nutrient uptake and translocation by Indian Mustard

Plants that hyperaccumulate metals are ideal subjects for studying the mechanisms of metal and mineral nutrient uptake in the plant kingdom. Indian Mustard (Brassica juncea) has been shown to accumulate moderate levels of Cd, Pb, Cr, Ni, Zn, and Cu. In this experiment, 10 levels of Cd concentration treatments were imposed by adding 10-190 mg Cd kg(-1) to the soils as cadmium nitrate [Cd(NO3)2]. The effect of Cd on phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and the micronutrients iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in B. juncea was studied. Plant growth was affected negatively by Cd, root biomass decreased significantly at 170 mg Cd kg(-1) dry weight soils treatment. Cadmium accumulation both in shoots and roots increased with increasing soil Cd treatments. The highest concentration of Cd was up to 300 mg kg(-1) d.w. in the roots and 160 mg kg(-1) d.w. in the shoots. The nutrients mainly affected by Cd were P, K, Ca, Fe, and Zn in the roots, and P, K, Ca, and Cu in the shoots. K and P concentrations in roots increased significantly when Cd was added at 170 mg kg(-1), and this was almost the same level at which root growth was inhibited. Zn concentrations in roots decreased significantly when added Cd concentration was increased from 50 to 110 mg kg(-1), then remained constant with Cd treatments from 110 to 190 mg kg(-1). However, Zn concentrations in the shoots seemed less affected by Cd. It is possible that Zn uptake was affected by the Cd but not the translocation of Zn within the plant. Ca and Mg accumulation in roots and shoots showed similar trends. This result indicates that Ca and Mg uptake is a non-specific process.     

Indoor and outdoor household dust contamination in Cincinnati, Ohio, USA

Despite some progress in reducing the average lead level in the USA, the streets of Cincinnati, Ohio, are still contaminated by heavy metals. High levels of heavy metals will have significant unequivocal ecological impacts and pose a potential health hazard. This study evaluates the level of heavy- metal contamination in household dust and examines its relationships with the external environment. Samples of outdoor and indoor dust were collected from middle-income residential homes in the Greater Cincinnati Metropolitan District and the metal content was analysed by inductively coupled plasma atomic emission spectrophotometry. Results showed that the mean levels of lead in outdoor and indoor dusts are 650 g g-1 and 377 g g-1 and the copper levels are 253 g g-1 and 510 g g-1, respectively. The median levels are 156 g g-1 and 139 g g-1 for outdoor and indoor lead dusts and 35 g g-1 and 124 g g-1 for outdoor and indoor copper dusts. The degree of contamination may be ascribable to the age of the dwelling unit and the neighbourhood, the time when the unit was last painted, the presence of pets and the type of space heating. In addition, car exhausts seems to be a possible source of contamination.     

Improvement of detection method of Cryptosporidium and Giardia in reclaimed water

Cryptosporidium and Giardia are two typical species of pathogenic protozoans that seriously endanger water quality. Previous works indicated that detection of Cryptosporidium and Giardia with modified United States Environmental Protection Agency (USEPA) method-1623 using a membrane filtration-elution for sample concentration attained better recovery and lower cost compared to the USEPA method-1623. Several improvements of membrane filtration-elution step as well as immunomagnetic separation (IMS) steps were investigated and an optimized method for detection of Cryptosporidium and Giardia in wastewater reclamation system was recommended in this paper. The experimental results show that an overnight soak of the membrane after scraping and vortex agitation before elution could enhance and stabilize the recovery. Increasing turbidity to 4 NTU by adding kaolin clay before filtration could effectively improve the recovery of low-turbidity water. Washing the concentrate after centrifugation and twice acid dissociation both reduced the impact of water quality to protozoan recovery. Protozoans in different water samples were determined by this optimized method, and the recovery of Cryptosporidium and Giardia were above 70% and 80% respectively, much higher than the acceptance of method-1623. __________ Translated from Environmental Science, 2006, 27(12): 2547–2552 [译自: 环境科学]     

马尔科夫链在环境质量预测中的应用

鉴于目前环境质量预测在理论方法和实践上的缺乏,把马尔科夫链引入环境质量的预测中,将各种污染物的浓度变化过程视作马尔科夫过程,通过预测各种污染物的污染负荷系数来推知其浓度值.实例中通过多元回归分析计算出马尔科夫转移矩阵,以2005年辽宁省5种大气污染物的污染负荷系数作为初始向量,预测了今后5年的变化.然后利用GM(1,1)模型预测出降尘的具体浓度值,由此计算出了2006～2010年辽宁省5种污染物的浓度值.     

近40年来长江流域水沙变化趋势及可能影响因素探讨

利用Mann Kendall方法,分析了近40年长江流域主要水文站点（长江干流水文站：屏山站、宜昌站、汉口站与大通站;支流水文站：嘉陵江的北碚站和汉江的皇庄站）的流量及输沙率的变化特征。结果表明：①长江流域流量与输沙量变化受人类活动（土地利用、水利设施建设等）与自然因素（如降水的时空变化）综合因素影响,变化趋势表现出复杂性,上、中、下游各有特点;②长江流域屏山站以上流域输沙率有上升趋势（1~5月份上升趋势达到95%的置信度水平）,这与上游河床坡度较大,使泥沙不易沉积以及暴雨与降水增加有关;③长江中下游输沙呈显著下降趋势。计算结果表明,宜昌-汉口河段是长江流域泥沙主要沉积区,加上葛州坝与三峡工程的建成与投入使用,从而进一步使中下游输沙量呈下降趋势。由于下游降水增加,使下游径流量自1980s以来有微弱上升趋势,但未达到95%的置信度水平,中上游流量变化不显著。对上、中、下游人为因素与自然因素对流域流量与输沙量的变化贡献率方面需要做进一步的研究。     

石化工业园区区域环境风险后评价的风险识别

松花江污染事故发生后,国家更加重视对已有石化工业园区的风险排查以及事故预防,风险识别是风险评价与管理的基础。通过查阅相关资料以及类比分析,分析了已有区域风险识别与普通风险识别的不同,探讨了识别的原则和重点,指出了识别的程序和相应的方法,并给出了实例论证,为区域环境风险识别研究提供借鉴。