滏阳河河流水体中重金属污染特征及其对青海弧菌和斜生栅藻的毒性效应

为调查滏阳河水系的重金属污染状况,研究河流重金属污染对水生生物的毒性,根据河流结构、水文条件、排污口分布并考虑空间分布的均匀性,选取66个采样位点,采集河水及对应的表层沉积物样品,分析了样品中的重金属含量。用斜生栅藻和青海弧菌Q67作为模式生物,根据滏阳河水重金属污染较严重的邯郸近郊2号采样点采集水样的重金属含量配制系列重金属浓度的模拟河水进行重金属污染河水的生态毒性测试。结果表明,在全部66个采样点中,29个采样点河水重金属含量超过国家地表水III类水体重金属含量标准,主要污染元素是Hg、Pb、Cr、Zn。几乎所有采样点河水Mn和Fe含量都大大高于国家集中式生活饮用水地表水源地补充项目规定的标准限值。根据2号采样点河水样品中的重金属含量配成的模拟河水对青海弧菌Q67的EC_(50)值为6.65%,为毒性极强的污染物。模拟河水样品对斜生栅藻的抑制作用较小,在实验的最高浓度下(1 000倍河水重金属含量)暴露4 d尚未引起半数藻细胞死亡。随河水重金属浓度上升,斜生栅藻超氧化物歧化酶(SOD)活性总体上呈现先升高后降低的趋势,丙二醛(MDA)含量变化则与此相反,反映河水重金属污染可引起藻细胞的氧化损伤。叶绿素a和b含量则随暴露浓度的提高逐渐降低。在重金属浓度达到2号采样点河水的10%时,斜生栅藻叶绿素a含量已有显著降低,MDA含量显著升高,海河流域重金属污染对生态系统的影响应予以重视。河水发光菌Q67的生长抑制率、斜生栅藻的叶绿素a和MDA含量可以作为评估河流重金属污染生态危害的指标。     

Competing land uses and fossil fuel,and optimal energy conversion rates during the transition toward a green economy under a pollution stock constraint

We study the transition to a carbon-free economy in a model with a polluting non-renewable resource and a clean renewable resource. Transforming primary energy into ready-to-use energy services is costly and more efficient energy transformation rates are more costly to achieve. Renewable energy competes with food production for land and the food productivity of land can be improved at some cost. To avoid catastrophic climate damages, the pollution stock is mandated to stay below a given cap. When the economy is not constrained by the cap, the efficiency of energy transformation increases steadily until the transition toward the ultimate green economy; when renewable energy is exploited, its land use rises at the expense of food production; food productivity increases together with the land rent but food production drops; the food and energy prices increase and renewables substitute for non-renewable energy. During the constrained phase, the economy follows a constant path of prices, quantities, efficiency rates, food productivity and land rent, a phenomenon we call the ‘ceiling efficiency paradox’.     

Environmental policy and human capital inequality: A matter of life and death

This paper analyzes the economic implications of an environmental policy when we account for the life expectancy of heterogeneous agents. In a framework in which everyone suffers from pollution but health status also depends on individual human capital, we find that the economy may be stuck in a trap in which inequality rises steadily, especially when the initial pollution intensity of production is too high. We emphasize that such inequality is in the long run costly for the economy in terms of health and growth. Therefore, we study whether a tax on pollution associated with an investment in pollution abatement can be used to address this situation. We show that a stricter environmental policy may allow the economy to escape from the inequality trap while enhancing the long-term growth rate when the initial inequality in human capital is not too large.     

The impact of flooding on property prices: A repeat-sales approach

In this paper we use a repeat-sales model to analyse the price path of properties affected by flooding in England between 1995 and 2014. Our dataset contains information on 4.8 million houses with at least one repeat-sale. This database is merged with high-definition GIS data delineating the spatial extent of all recorded flood incidents in England covering a total area of 2,654 km². Our results show that immediately after a flood event the price of property in a postcode entirely inundated by inland flooding is on average 24.9% lower than non-flooded property, whereas for property in a postcode entirely inundated by coastal flooding the price reduction is 21.1%. Nonetheless, we find that this discount is short-lived and the discount is no longer statistically significant for properties affected by inland flooding after 5 years, which falls to just 4 years for properties affected by coastal flooding. For lower-priced properties however, the post-flood price discount can be observed up to 6–7 years for both inland and coastal flooding. The magnitude of the impact also depends on the characteristics of the properties, the characteristics of the flood and the existence of flood protection assets.     

Infant health impacts of freshwater algal blooms: Evidence from an invasive species natural experiment

Economists are increasingly interested in causally interpretable estimates of environmental health externalities, particularly on infant health. This paper focuses on a specific case by investigating microcystin, a toxin produced by freshwater blue-green algal blooms. We exploit a natural experiment caused by a zebra mussel die-off in a large lake located in the state of Michigan, USA to identify changes in microcystin-related infant outcomes surrounding the lake. Using both the synthetic control method and a difference-in-differences strategy, we find that instances of low birth weight around the lake fell by 1.4 percentage points after lake water quality improved. Along the intensive margin, birth weight and length of gestation increased by 17.1 g and 0.47 weeks, respectively. Improvements to low birth weight result in $768,500 in average annual hospitalization cost savings. Many robustness and falsification tests are performed including using both annual and monthly data and accounting for possible weather confounders and seasonality. Results suggest that microcystin can affect infant health at levels below current water advisory guidelines.     

The price of innovation: An analysis of the marginal cost of green buildings

Energy efficiency plays an important role in reducing the carbon externality from buildings, but economic analyses of more efficient, green building have thus far ignored input costs. This paper finds that the average marginal cost of green-labeled construction projects is smaller than the value premiums documented in the literature. However, design fees, representing just a fraction of development costs but paid largely up-front, are significantly higher for green construction projects. These projects also take longer to complete. The results provide some insight into the market barriers and market failures that may explain the relatively slow adoption of otherwise economically rational green construction practices.     

Mercury: An agent of poverty in Ghana's small-scale gold-mining sector?

There is consensus worldwide that the artisanal and small-scale mining (ASM) sector is comprised of individuals who are trapped in a vicious cycle of poverty, lacking the necessary financial and technological means to improve their standards of living. Minimal work, however, has been undertaken to identify the very factors behind miners’ plight, which inevitably vary from country to country. This paper uses a case study of Ghana to argue that an increased dependence upon mercury for amalgamation in artisanal gold-mining communities is one such—albeit overlooked—“agent of poverty”. There is mounting empirical evidence which suggests that dealings with the monoponistic middlemen who supply mercury, purchases of costly medicines to remedy ailments caused by mercury poisoning, and a lack of appropriate safeguards and alternatives to amalgamation, are preventing gold miners from improving their practices and livelihoods. The solution to the problem lies in breaking this cycle of dependency, which can be achieved by providing miners with robust support services, mercury-free technologies and education.     

发光菌Q67对污染源水体的毒性研究

发光菌作为指示生物用于环境毒物毒性测定具有快速、灵敏、低廉等优点,现已广泛用于环境毒物综合急性毒性测定、筛查、监测及特异毒物监测中。本项目利用淡水发光菌Q67对吉林地区各行业典型企业的出水口进行急性毒性试验,同时结合化学指标进行了综合评估,试验结果表明：急性毒性试验和化学指标并非在任何水体都相关,但是,急性毒性试验是化学试验的必要补充。     

The Influence of Enhanced Side Impact Protection on Kinematics and Injury Measures of Far- or Center-Seated Children in Forward-Facing Child Restraints

Objective: To evaluate the influence of forward-facing child restraint systems’ (FFCRSs) side impact structure, such as side wings, on the head kinematics and response of a restrained, far- or center-seated 3-year-old anthropomorphic test device (ATD) in oblique sled tests.

Methods: Sled tests were conducted utilizing an FFCRS with large side wings and with the side wings removed. The CRS were attached via LATCH on 2 different vehicle seat fixtures—a small SUV rear bench seat and minivan rear bucket seat—secured to the sled carriage at 20° from lateral. Four tests were conducted on each vehicle seat fixture, 2 for each FFCRS configuration. A Q3s dummy was positioned in FFCRS according to the CRS owner's manual and FMVSS 213 procedures. The tests were conducted using the proposed FMVSS 213 side impact pulse. Three-dimensional motion cameras collected head excursion data. Relevant data collected during testing included the ATD head excursions, head accelerations, LATCH belt loads, and neck loads.

Results: Results indicate that side wings have little influence on head excursions and ATD response. The median lateral head excursion was 435 mm with side wings and 443 mm without side wings. The primary differences in head response were observed between the 2 vehicle seat fixtures due to the vehicle seat head restraint design. The bench seat integrated head restraint forced a tether routing path over the head restraint. Due to the lateral crash forces, the tether moved laterally off the head restraint reducing tension and increasing head excursion (477 mm median). In contrast, when the tether was routed through the bucket seat's adjustable head restraint, it maintained a tight attachment and helped control head excursion (393 mm median).

Conclusion: This testing illustrated relevant side impact crash circumstances where side wings do not provide the desired head containment for a 3-year-old ATD seated far-side or center in FFCRS. The head appears to roll out of the FFCRS even in the presence of side wings, which may expose the occupant to potential head impact injuries. We postulate that in a center or far-side seating configuration, the absence of door structure immediately adjacent to the CRS facilitates the rotation and tipping of the FFCRS toward the impact side and the roll-out of the head around the side wing structure. Results suggest that other prevention measures, in the form of alternative side impact structure design, FFCRS vehicle attachment, or shared protection between the FFCRS and the vehicle, may be necessary to protect children in oblique side impact crashes.     

Effectiveness of China's National Forest Protection Program and nature reserves

There is profound interest in knowing the degree to which China's institutions are capable of protecting its natural forests and biodiversity in the face of economic and political change. China's 2 most important forest‐protection policies are its National Forest Protection Program (NFPP) and its national‐level nature reserves (NNRs). The NFPP was implemented in 2000 in response to deforestation‐caused flooding. We undertook the first national, quantitative assessment of the NFPP and NNRs to examine whether the NFPP achieved its deforestation‐reduction target and whether the NNRs deter deforestation altogether. We used MODIS data to estimate forest cover and loss across mainland China (2000–2010). We also assembled the first‐ever polygon dataset for China's forested NNRs (n = 237, 74,030 km² in 2000) and used both conventional and covariate‐matching approaches to compare deforestation rates inside and outside NNRs (2000–2010). In 2000, 1.765 million km² or 18.7% of mainland China was forested (12.3% with canopy cover of ≥70%)) or woodland (6.4% with canopy cover <70% and tree plus shrub cover ≥40%). By 2010, 480,203 km² of forest and woodland had been lost, an annual deforestation rate of 2.7%. Forest‐only loss was 127,473 km² (1.05% annually). In the NFPP provinces, the forest‐only loss rate was 0.62%, which was 3.3 times lower than in the non‐NFPP provinces. Moreover, the Landsat data suggest that these loss rates are overestimates due to large MODIS pixel size. Thus, China appears to have achieved, and even exceeded, its target of reducing deforestation to 1.1% annually in the NFPP provinces. About two‐thirds of China's NNRs were effective in protecting forest cover (prevented loss 4073 km² unmatched approach; 3148 km² matched approach), and within‐NNR deforestation rates were higher in provinces with higher overall deforestation. Our results indicate that China's existing institutions can protect domestic forest cover.