Generalized propensity score approach to causal inference with spatial interference

Many spatial phenomena exhibit interference, where exposures at one location may affect the response at other locations. Because interference violates the stable unit treatment value assumption, standard methods for causal inference do not apply. We propose a new causal framework to recover direct and spill-over effects in the presence of spatial interference, taking into account that exposures at nearby locations are more influential than exposures at locations further apart. Under the no unmeasured confounding assumption, we show that a generalized propensity score is sufficient to remove all measured confounding. To reduce dimensionality issues, we propose a Bayesian spline-based regression model accounting for a sufficient set of variables for the generalized propensity score. A simulation study demonstrates the accuracy and coverage properties. We apply the method to estimate the causal effect of wildland fires on air pollution in the Western United States over 2005–2018.     

Life expectancy of spruce needles under extremely high air pollution stress: performance of trees in the Ore Mountains

Summary Photosynthetic performance of Norway spruce needles [Picea abies (L.) Karst.] was measured over a 1-year period. The trees grew in an area of heavy air pollution and forest decline on a mountain ridge in the eastern Ore Mountains (Czech Republic). Photosynthetic capacity, as well as light use efficiency, decreased dramatically with time, starting in July (2 months after bud-break) to finally reach zero (respiration only) by February of the following year. Two months later all needles from upper crown parts were shed. Needles from lower crown parts, on the other hand, were undamaged. The chlorophyll and Mg content decreased transiently during the cold season, with Mg reaching deficiency thresholds during winter. However, total sulfur, as well as organic and sulfate S increased with time. The increase was higher in needles from the upper parts of the crown, which were exposed to windy air throughout the year, than in the lower parts of the crown, which were covered by grass during summer and by snow during most of the winter.     

Effect of 6-benzyladenine and Casein Hydrolysate on Micropropagation of Amorpha fruticosa

Pisum sativum L. cv. Phenomen plants were grown in pots in greenhouse and their growth, and ATP and chlorophyll (Chl) a and b contents were assessed after 9-d exposure to sodium arsenate [0.04 and 0.07 mmol kg^–1(soil)], or to lead acetate [2.0 and 4.0 mmol kg^–1(soil)], or zinc acetate [5.3 and 9.3 mmol kg^–1(soil)]. The luciferin-luciferase method was used for ATP analyses. Soil pollution reduced significantly the growth, but the low toxicant concentrations elevated the cotyledon and shoot ATP concentrations per fresh matter content. The ATP/Chl ratio was increased in the zinc-treated seedlings as compared with the respective controls. The ATP concentration and a number of growth parameters were negatively correlated, and thus the high ATP content might contribute to the significantly reduced growth of seedlings.     

Spatial and temporal variability of nutrient retention in river basins: A global inventory

Nutrient export by rivers may cause coastal eutrophication. Some river basins, however, export more nutrients than others. We model the Basin-Wide Nutrient Export (BWNE) Index, defined as nutrient export by rivers as percentage of external nutrient inputs in the basins. We present results for rivers worldwide for the period 1970–2050. The results indicate that nutrient retentions differ largely among basins. They indicate that BWNE increases with nutrient inputs to the land, indicating that the percentage of, for instance, fertilizers exported to sea increases with fertilization rate. We argue that a better understanding of the BWNE Index might help to identify where measures and technologies to reduce nutrient inputs to coastal waters are most effective.     

Survey of atmospheric heavy metal deposition in Suqian using moss contamination

Abstract

Heavy metal pollution in the atmosphere is a major environmental problem, which has important impacts on ecosystems and human health. In this study, the atmospheric deposition of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) in Suqian, China, was investigated by using the moss Haplocladium microphyllum as a bioindicator. The survey was carried out during the summer of 2017 at 40 homogenously distributed sampling sites. Cr, Cu, Ni, Pb, V, and Zn were analyzed by inductively coupled plasma atomic emission spectrometry, and Cd was analyzed by inductively coupled plasma mass spectrometry. Wide variations in heavy metals (Cd, Pb, and Zn) indicated that the concentrations of elements are influenced by local emission sources. Spatial distribution maps of the elements were constructed using geographic information system technology. The pollution load index showed that the study area was moderately polluted to unpolluted. Significant positive correlations (p?<?.01) and weak positive correlations (p?<?.05) were identified among some of the elements, indicating that they originated from common sources. A principal component analysis classified the heavy metals into natural and anthropogenic sources, and identified four primary sources: nature soil dust, industry activities, traffic emission, and agricultural activities.     

城市环境中树木年轮的变异及其与工业发展的关系

通过对污染敏感树种油松年轮宽度和元素含量的变异与沈阳工业发展的相关分析。追溯和重建沈阳地区的生态环境变迁史,揭示城市环境质量与树木年轮变异之间的相关规律。结果表明,在城市污染条件下,树木年轮宽度和微量元素含量均发生了明显的变异,而且这些变异与沈阳工业发展显著相关．     

重金属Cd－Zn对水稻的复合污染和生态效应

重金属Ｃｄ－Ｚｎ对水稻的复合污染和生态效应周启星（浙江农业大学,杭州３１００２９）吴燕玉,熊先哲（中国科学院沈阳应用生态研究所,１１００１５）ＣｏｍｐｏｕｎｄｐｏｌｌｕｔｉｏｎｏｆＣｄａｎｄＺｎａｎｄｉｔｓｅｃｏｌｏｇｉｃａｌｅｆｆｅｃｔｏｎｒｉｃｅ...     

Antlers as biomonitors of environmental pollution by lead and fluoride: A review

Antlers are periodically cast and re-grown cranial appendages of deer. Both endochondral and intramembranous ossification are involved in the formation of antler bone. After velvet shedding, antlers are completely bony structures which are referred to as hard antlers. Growing antlers accumulate substances with an affinity to mineralized tissues. Among these substances are lead and fluoride. Due to the seasonally limited life span of antlers, the concentrations of lead and fluoride in hard antlers reflect uptake by the forming bone during a defined, species-specific period of some months. Antlers can thus be viewed as naturally standardized environmental samples that are well suited as biomonitors of environmental pollution by bone-seeking contaminants. Because hard antlers are collected by hunters as trophies and kept in private or public collections, material for study can be obtained rather easily. So far, lead concentrations in hard antlers have been reported only from Europe, whereas data for fluoride are available from both Europe and North America. Some studies compared contaminant concentrations in antlers from different regions, while others analyzed time-trends in contaminant levels in antlers from a single region. Using the latter approach, a pronounced drop of lead concentrations during recent decades has been reported for antlers from various European countries. This indicates a marked decline of environmental lead levels that can be attributed mainly to the phase-out of leaded gasoline and, in addition, to a reduction of lead emissions also from stationary sources. In Germany, a corresponding drop has also been recorded for fluoride concentrations in antlers, which is attributed to a decline of fluoride emissions from stationary sources due to improved emission-control measures. There is some evidence that exposure to higher levels of fluoride may lead to an impaired antler mineralization. Using antlers as biomonitors has been shown to be an efficient method for assessing environmental pollution by lead and fluoride at low cost. Further studies using this now well established approach are therefore encouraged.This revised version was published online in May 2005. The following errors were eliminated:1. In the chapter Antler growth and mineralization in the last sentence of the first paragraph a slash was missing between the words reindeer and caribou; 2. In the second paragraph of the same chapter the word reiudees was corrected to reindeer; 3. In the chapter Accumulation of lead and fluoride in growing antlers the word lightest was corrected to highest.     

株洲工业区土壤重金属污染与蚯蚓同工酶的研究

用聚丙烯朊胺凝胶圆盘电泳法对蚯蚓酯酶及过氧化物酶同工酶进行比较研究,结果表明,重金属在蚯蚓体内富集量随污染程度增加而上升,重污染区为中污染区的２．２７倍,为轻污染区的７．３０倍,重污染区Ｃｄ、Ｐｂ、Ａｓ在蚯蚓体内分别达到４７．３、３５．２、１６．３２μｇ．ｋｇ＾－１。其秩相关系数（ｒ５）〉０．６６－０．７７。蚯蚓酯酶同工酶酶带减少,酶活性降低,而其过氧化物酶酶带和酶活性有所增加。     

Purification of Cu, Zn-Superoxide Dismutase Isoenzymes from Fish Liver: Appearance of New Isoforms as a Consequence of Pollution

Liver cell-free extracts of fish (Mugil sp.) from polluted environments show new Cu, Zn-SOD isoenzymes when analyzed by polyacrylamide gel electrophoresis or isoelectrofocusing followed by in situ staining for SOD activity. The most active isoenzymes, with pI 6.1 and 5.1, were present both in control and problem samples while the isoenzymes of intermediate pI value showed significant differences. Fish from control areas showed three intermediate isoenzymes with pI 5.7, 5.5 and 5.4 (the last one quite faint) while polluted animals showed three bands of pI 5.9, 5.45 and 5.35, this last very intense. To further characterize their utility as biomarkers, Cu, Zn-SOD isoenzymes from polluted fish livers were purified to homogeneity. Five superoxide dismutase peaks were purified, named thereafter I (pI 6.1) to V (pI 5.1) respectively. Isoenzymes I and V displayed the highest specific activity. Upon incubation with moderate H₂O₂ concentrations, pure isoenzyme I yielded more acidic bands with pI 5.5, 5.45 and 5.35, this last being predominant. The pure isoenzyme V generated only a new band of pI 5.0. Concomitant with oxidation, the activity of peaks I and V was lost in a H₂O₂ concentration-dependent manner. The pattern of the new acidic bands generated upon the oxidixing treatment of isoenzyme I closely resembles that observed in crude extracts from polluted animals.