Zinc and cadmium accumulation and tolerance in populations of Sedum alfredii

To investigate the variation of Zn and Cd accumulation and tolerance of Sedum alfredii (a newly reported Zn/Cd hyperaccumulator), field surveys and hydroponic experiments were conducted among three populations of this species: two originating from old Pb/Zn mines in Zhejiang (ZJ) and Hunan (HN) Provinces and one from a "clean" site in Guangdong (GD) Province, China. Under field conditions, up to 12,524 and 12,253 mg kg(-1) Zn, and 1400 and 97 mg kg(-1) Cd in shoots of ZJ and HN plants were recorded respectively. Under hydroponic conditions, ZJ and HN plants accumulated significantly higher Zn and Cd in their leaves and stems, and possessed significantly higher Zn and Cd tolerance than GD plants. Among the two contaminated populations, ZJ plants showed higher Cd tolerance and accumulation (in leaves) than HN plants. The present results indicate that significant differences in Zn and Cd accumulation and tolerance exist in populations of S. alfredii.     

旅游购物体验实证研究——以屯溪老街为例

在文献综述的基础上,以屯溪老街为例,运用单因素方差分析方法,从旅游主客体两个方面探讨了旅游者的购物体验及其差异性。在主体方面,旅游者的职业、收入、年龄等社会经济属性和游览时间、购物花费等旅游行为特性变量构成了购物体验的差异性因素;在客体方面,旅游者对于老街的购物环境、商品和服务属性方面的体验差异性显著。最后有针对性地提出了管理措施。     

Reproduction in a simultaneous hermaphroditic shrimp, Lysmata wurdemanni: any two will do?

The caridean shrimp Lysmata wurdemanni (Gibbes) displays protandric simultaneous hermaphroditism with out-crossing, but not all males become simultaneous hermaphrodites (euhermaphrodites). In this laboratory study, we attempted to determine why some shrimp remain males. In our experiment, we grew L. wurdemanni from postlarvae to adults in several group sizes and observed their reproductive function. We found that all shrimp reared in isolation become euhermaphrodites. When cultured in a group, the proportion of shrimp remaining male decreased with increasing group size. Except for those that mated within a day, inter-molt euhermaphrodite-phase shrimp (with or without embryos) and inter-molt male-phase shrimp fertilized eggs successfully. On the other hand, euhermaphrodite shrimp can only mate as females and have their eggs fertilized during a narrow post-molt window (less than 12 h) in each molt cycle (10 days). The fertilization rate of male-euhermaphrodite pairs was similar to that of euhermaphrodite-euhermaphrodite pairs. There are at least two non-exclusive explanations for the persistence of male shrimp in a group. In certain group compositions, an individual may gain more reproductive fitness as a large male with multiple mating partners than as a small female with low clutch size. Alternatively, the presence of male-phase individuals, with variable molt-cycle duration (5-8 days), may be necessary to ensure mating. This study is the first direct experimental demonstration of social control of sex change in the decapod crustaceans.     

Locating pollutant emission sources with optical remote sensing measurements and an improved one-dimensional radial plume mapping technique

Previous studies have shown that there was a relatively large amount of uncertainty along the major wind direction in the results of locating emission sources using the one-dimensional radial plume mapping (RPM(1D)) technique based on optical remote sensing measurements. This paper proposes setting up an additional monitoring line that is perpendicular to the original scanning beam geometry to reduce this uncertainty. We first conducted a computer simulation study using the Gaussian dispersion model to generate the downwind concentrations of plumes from 400 source locations in a 201 m × 201 m spatial domain under various wind directions (n = 181). The optical remote sensing instrument was assumed to be at (0, 0) with two perpendicular monitoring lines, each of which had three beam segments of equal length. Each pair of the reconstructed downwind concentration profiles was then used to trace back to the source locations. The results showed that the accuracy of the method and its uncertainty were improved by using the proposed two-line RPM(1D) approach rather than the original one-line RPM(1D) approach at most simulated source locations. In a follow-up field experiment, a tracer gas was released at the coordinate of (100, 100). The release location was covered within the 0.25- to 0.5-probability area of the estimated results, and the distance between the actual and estimated source locations was 18.4 m (9.2% of the longest beam path).     

盲样考核浓度预判及稀释方法——以原子荧光法测定水中砷为例

以原子荧光法测定水中砷为例,探讨了实验室盲样考核浓度预判及稀释方法.分析了3个砷盲样考核实例,归纳了“直接稀释法”“系列稀释法”“最大稀释法”3种方法,分别适用于盲样浓度范围窄、适中、宽3种情况,检测人员可根据考核机构给定的浓度范围合理选用.     

The backend design of an environmental monitoring system upon real-time prediction of groundwater level fluctuation under the hillslope

The groundwater level represents a critical factor to evaluate hillside landslides. A monitoring system upon the real-time prediction platform with online analytical functions is important to forecast the groundwater level due to instantaneously monitored data when the heavy precipitation raises the groundwater level under the hillslope and causes instability. This study is to design the backend of an environmental monitoring system with efficient algorithms for machine learning and knowledge bank for the groundwater level fluctuation prediction. A Web-based platform upon the model-view controller-based architecture is established with technology of Web services and engineering data warehouse to support online analytical process and feedback risk assessment parameters for real-time prediction. The proposed system incorporates models of hydrological computation, machine learning, Web services, and online prediction to satisfy varieties of risk assessment requirements and approaches of hazard prevention. The rainfall data monitored from the potential landslide area at Lu-Shan, Nantou and Li-Shan, Taichung, in Taiwan, are applied to examine the system design.     

Chemical forms and ecological risk of arsenic in the sediment of the Daliao River System in China

The chemical forms and ecological risk of As were characterized in the sediment of the Daliao River System (DRS), which has been affected by long-term intensive industrial, urban, and agricultural activities. Twenty-seven samples of surface sediment were collected and analyzed for total As content and that of its chemical forms. The results indicated that the average total As content in the sediment was 9.83 mg kg^− 1 but that the levels ranged from 1.57 to 83.09 mg kg^− 1. At the sites near cities, mining sites, and the estuary of the DRS, it is likely that adverse effects on aquatic organisms occur, due to As levels in the sediment that are often higher than the threshold effect level and occasionally higher than the probable effect level. A selectively sequential extraction indicated that the majority of As in the sediment was bound to Fe oxides (62.1%), with moderate proportions of residual As (19.8%), specifically adsorbed As (17.9%), and a low proportion of non-specifically adsorbed As (1.1%). In addition, the content of Fe in the sediment was positively and significantly correlated with the contents of amorphous and crystalline Fe oxide-bound As, confirming the crucial role of Fe oxides in immobilizing high amounts of As in superficial environments. The average molar ratio of As to Fe was 1.18 × 10^− 4 in the surface sediment of the DRS, similar to that of natural Fe oxides, but much lower than that of synthesized Schwertmannite. Therefore, the release of As under reduced and low pH conditions can cause serious problems for water resources and for living organisms.     

钢铁企业大型低位料仓汽车卸料的粉尘控制

某钢企大型低位料仓为汽车卸料,料仓厂房内空高,跨度大,料仓上部贯通,物料落差大,卸料中产生大量粉尘,环境污染问题典型突出。通过对低位料仓汽车卸料产尘特性分析,采取加强生产管理、组织汽车有序卸料、料仓厂房有效密闭、合理设计捕尘方式和布袋除尘系统等措施,能够有效地控制粉尘污染。除尘系统具有投资及运行费用少,除尘效果明显的优点。     

蔬菜常用农药在地下水中残留风险评估

为明确蔬菜常用农药在地下水中的环境风险,运用China-Pearl和SCI-GROW模型开展地下水环境暴露评估,并根据我国成人和儿童暴露参数推导25种农药预测无效应浓度(PNEC)。研究发现,25种农药PECgw为0~18.340μg·L-1,成年人PNECgw为0.003~19.654 mg·L-1,儿童PNECgw为0.001~23.253 mg·L-1。成年人和儿童的RQgw值均小于1,表明25种农药按照登记用量使用,我国成人和各年龄阶段儿童直接饮用施用农药区域地下水的环境风险可接受。