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61.
Organochlorine pesticides (OCPs) are a class of toxic and harmful persistent organic pollutants widely found in environment. Hexachlorocyclohexane (HCHs) and DDTs are two of the most widely used OCPs (Qiu et al., 2004), so it is important to find out their compositional characteristics and sources in surface sediments. Guanghai Bay is located in the south of Guanghai Bay Industrial Park in Taishan City, Guangdong Province. It borders Huangmaohai to the east and Zhenhai Bay to the west, covering an area of about 236 square kilometers. In this study, surface sediments were collected at 16 sites in Guanghai Bay (Fig. 1). After the surface sediments were pretreated, GC‐MS was used to analyze OCPs. A total of 14 OCPs were detected and their content was shown in Table 1. The concentration of ΣOCPs ranged between 0.507~0.860ng·g‐1, with an average of 0.680 ng?g‐1. In general, the content of ΣOCPs was the highest at No. A12 site. The concentrations of these 14 detected OCPs ordered as dieldrin > epoxy heptachlor > P, P'‐DDD > γ‐HCH >endrin >aldrin > P, P'‐DDE >mirex >hexachlorobenzene >P, P'‐DDT > α‐HCH > δ‐HCH >β‐HCH > heptachlor. 相似文献
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Yu Zhi Shi Xiuzhi Zhou Jian Gou Yonggang Rao Dijun Huo Xiaofeng 《Natural Resources Research》2021,30(6):4063-4078
Natural Resources Research - In the process of open-pit bench blasting for many mines, rock fragments move in the direction of loose space after fragmentation under explosive energy, leading to ore... 相似文献
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Journal of Oceanology and Limnology - The increases of atmospheric carbon dioxide and other greenhouse gases have caused fundamental changes to the physical and biogeochemical properties of the... 相似文献
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A new prediction model for grain yield in Northeast China based on spring North Atlantic Oscillation and late-winter Bering Sea ice cover
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Accurate estimations of grain output in the agriculturally important region of Northeast China are of great strategic significance for guaranteeing food security. New prediction models for maize and rice yields are built in this paper based on the spring North Atlantic Oscillation index and the Bering Sea ice cover index. The year-to-year increment is first forecasted and then the original yield value is obtained by adding the historical yield of the previous year. The multivariate linear prediction model of maize shows good predictive ability, with a low normalized root-mean-square error (NRMSE) of 13.9%, and the simulated yield accounts for 81% of the total variance of the observation. To improve the performance of the multivariate linear model, a combined forecasting model of rice is built by considering the weight of the predictors. The NRMSE of the model is 12.9% and the predicted rice yield explains 71% of the total variance. The corresponding cross-validation test and independent samples test further demonstrate the efficiency of the models. It is inferred that the statistical models established here by applying year-to-year increment approach could make rational prediction for the maize and rice yield in Northeast China before harvest. The present study may shed new light on yield prediction in advance by use of antecedent large-scale climate signals adequately. 相似文献
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GPS Solutions - We evaluate the performance of Galileo broadcast NeQuick model by comparing it with GPS broadcast Klobuchar and the original NeQuick2 models. The broadcast coefficients of Galileo... 相似文献
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构建早稻雨洗花灾害指标及适于早稻产量估算的灾损评估模型,对开展早稻雨洗花灾害监测、损失评估、灾害保险等具有重要意义。该文以江西省早稻为研究对象,利用1981-2015年14个水稻气象观测站逐日气象资料和农业气象观测资料,筛选出基于早稻抽穗扬花期间过程降水量、最大降水量、降水日数及实际产量的雨洗花灾害样本78个,在此基础上,利用相关分析、正态分布以及主成分回归法,建立了雨洗花灾害指标和灾损评估模型,并对其进行验证。结果表明:抽穗扬花期降水对雨洗花灾害形成有显著影响,其主要影响时段为抽穗扬花普遍期前后5 d内,关键时段为抽穗扬花普遍期前后3 d内。日降水量40 mm可作为早稻抽穗扬花期雨洗花灾害临界指标。以该指标为基础,统计日降水量不低于40 mm的降水日数及其对应的累积降水量,当累积降水量为40~170 mm时,为轻度雨洗花灾害,早稻一般减产小于15%,平均减产10%;当累积降水量不小于170 mm时,为重度雨洗花灾害,早稻一般减产不低于15%,平均减产22%。指标验证结果与历史实际灾害发生情况有较好的一致性。雨洗花灾损评估模型检验结果表明:雨洗花年模拟产量与实际产量吻合度较高,平均相对模拟误差为4.3%,78.0%的资料相对误差在5%以内,可利用该模型对雨洗花年的早稻减产率进行模拟和预测。 相似文献