Historical pollution trends in coastal environments of India

Seventeen sediment cores were collected from different coastalecosystems of Tamil Nadu, India that include coastal lagoon (Pulicat), polluted rivers in Chennai (Adyar and Cooum), Coral reef (Gulf of Mannar) and a perennial river (Tamiraparani).Radiometric dating has been used to determine the modern sedimentation rates in these ecosystems. The Pulicat Lake and thepolluted rivers (Adyar and Cooum) yield an average sediment accumulation rate of 12.34 and 7.85 mm yr^-1, respectively. Inthe Gulf of Mannar coral reef, the sedimentation rate averages 17.37 mm yr^-1, while the rate in Tamiraparani River is 11.00 mm yr^-1. In the Tamiraparani River basin, the deposition rates were an order of magnitude higher when compared to the erosion rates, which may be due to bank erosion and the intense human activity. In general high rates of sedimentation observed in the coastal ecosystems not only reflect the capacity of the coastal regions as sinks for trace metals but also denoteincreased input of pollutants into the coastal environments in the recent past. The deposition rates of heavy metals – Fe, Mn,Zn, Cu, Cr and Ni in the depth profiles have been computed using sedimentation rates and their distribution is discussed. It can be seen that the mean deposition rates of all the measured elements in the Tamil Nadu coastal ecosystems are high compared with rates determined for the sediments of the deltaic regions ofIndia and the Bay of Bengal.     

Challenges to Introducing and Managing Disturbance Regimes for Holocarpha macradenia, an Endangered Annual Grassland Forb

Abstract:  Introducing rare plants to new sites for conservation to offset effects of habitat destruction requires detailed knowledge of habitat requirements, plant demography, and management needs. We conducted a factorial experiment replicated at three coastal prairie sites to test the effects of clipping frequency and litter accumulation on seed germination, seedling survival, reproduction, and seedling recruitment of introduced populations of the endangered, tall-stature, annual forb, Holocarpha macradenia (DC.) E. Greene. Clipping favored H. macradenia , primarily by enhancing seed germination and flower production. Litter accumulation had no effect on seed germination, even after 5 years of treatments. Seedling recruitment was highly site specific with large numbers of recruits recorded at only one of three sites. Although recruitment of seedlings was higher in clipped plots for 2–3 years, by 4–5 years after introduction very few seedlings survived to reproduction in any treatment. We attribute this result to a combination of poor habitat quality, small population size, and lack of a seed bank. We were unsuccessful in introducing this relatively well-studied species of concern to apparently suitable habitat at multiple sites in multiple years, which suggests that translocating rare plant populations to mitigate for habitat destruction is an expensive and highly uncertain endeavor.     

Organic matter composition in sediments of the Oman Margin

The quantity and biochemical composition of organic matter (OM) in the sediments underlying and below oxygen minimum zone (OMZ) in the Arabian Sea were studied to provide information on the diagenetic processes of organic carbon under different environmental conditions. Concentrations of total organic carbon (TOC), total nitrogen (TN) and total hydrolysable amino acids (THAA) were significantly higher in sediments within rather than below OMZ, while those of total carbohydrates (TCHO) were slightly lower in the latter, suggesting the presence of a larger supply of labile compounds into the sea bottom at the shallower site (i.e. within OMZ). Hydrolysable amino acid and carbohydrate contribution to TOC were even lower (about 10% in surficial sediments) than the values obtained from the abyssal oligotrophic North Pacific, suggesting that OM food availability in the Oman Margin sediments within OMZ was lower than that observed at abyssal depths. The presence of the highest THAA and TCHO concentrations in the top 40 mm of the sediment core at both sites reflected the presence of bioturbation processes. In contrast with the general view of the deep sea as a stable and constant system, below OMZ in the Arabian Sea sediments, some differences were observed in the two investigated cores indicating the presence of a certain spatial variability in OM content and diagenesis.     

风力发电场环境监理中风机敏感距离的测量

风电项目环境监理过程中需重点关注风机环境防护距离内有无环境敏感点。介绍了几种适用于风电项目环境监理测量距离的方法,并且对每种方法的适用范围及操作做了详细阐述。     

Long-term dynamics of radioactive <Superscript>90</Superscript>Sr and <Superscript>137</Superscript>Cs contamination of small mammals in the Chernobyl zone

Between 1986 and 1994, a decrease in nonalimentary ⁹⁰Sr and ¹³⁷Cs intake and changes in the accessibility of radionuclides in the soil-plant link of their cycle resulted in a 10-to 100-fold decrease in their specific activity (SA) in the bodies of small mammals inhabiting the Chernobyl zone, and a similar decrease was observed in the radionuclide transition factor (TF) in the soil-animal chain. Between 1995 and 2005, no consistent increase or decrease in SA or TF could be revealed against the background of a combined effect of different physicochemical and ecological factors. It is suggested that subsequent changes in the level of radioactive contamination of small mammals will generally reflect only the dynamics of physical ⁹⁰Sr and ¹³⁷Cs decay, but, nevertheless, seasonal and local variations in this level will be significant.     

某滨海核电厂冷源取水口生物调查及风险分析

近年来由海洋生物入侵造成的滨海核电冷源安全事件频发,为了解某核电厂取水口海域的生物概况,本研究于2022年9月至2023年8月进行了生物调查。共获得海洋生物10类211种,优势种以脊索动物和甲壳动物为主,5月、7月下旬至8月上旬出现2个生物量高峰期。风险生物有中国毛虾（Acetes chinensis）、中华假磷虾（Pseudeuphausia sinica）、日本鳀（Engraulis japonicus）、球型侧腕水母（Pleurobrachia globosa）等,并初步分析了日本鳀和中国毛虾在取水口海域激增的原因。本文明确了某核电冷源的生物风险期为4－9月,研究成果将有助于优化核电厂生物灾害的预警和防控工作。     

围塘养殖与“退塘还湿”对滨海蓝色碳汇的影响

滨海蓝碳生态系统是重要的天然碳汇。在经济发展与生态环境保护博弈过程中,不少沿海区域经历了“自然湿地−围塘养殖−退塘还湿”的转变。本文从滨海蓝色碳汇的功能重要性出发,结合新时期湿地保护修复等国家重大举措,概要了我国滨海蓝色碳汇能力,梳理了国内外学者对自然滨海湿地、围塘养殖和“退塘还湿”区域碳汇功能特点及变化机制的探讨,针对目前的研究进展提出了研究不足及研究展望,即加强长期连续性研究、多站点对比研究和多界面机制研究。本文有望为提升滨海蓝色碳汇能力及评价湿地修复效果提供策略参考。     

中国滨海湿地的蓝色碳汇功能及碳中和对策

为摸清全球气候变化背景下,我国海岸带蓝碳应对气候变化的发展状况,发掘我国海岸带蓝碳减缓与适应气候变化的潜力,分析了我国海岸带蓝碳生态系统的基本状况及保护恢复情况,阐述了海岸带蓝碳对气候变化的影响及响应机制,论述了我国海岸带蓝碳发展面临的形势及管理需求。最后,提出了我国海岸带蓝碳应对气候变化的发展建议,即推进海岸带蓝碳管理政策的制定和实施,实现我国海岸带蓝碳的系统性监测,积极开展受损蓝碳生态系统修复案例的研究,加强海岸带蓝碳保护与修复的公众参与度,增强国际合作。

     

盛行梯度风下热力环流对近地空气质量的影响研究

以中纬度沿海城市上海为代表,采用数值模拟方法,分析了海岸线附近污染源排放的大气污染物在盛行梯度风和热力环流耦合作用下的扩散和输送特征,并与忽略海陆温差的理想情况作了对比.结果表明,即使在盛行梯度风主导城市风场时,海陆温差引起的热力环流对海岸线附近流场仍有重要影响,并使近地面污染物浓度时空分布与海陆无温差时截然不同.海陆无温差时,污染物仅向盛行梯度风的下风向区域扩散.而在海陆有温差时,污染物的扩散却可能是双向的.陆地最高和最低气温出现的时间分别对应着沿海城市污染物最不利释放时段(RTS-16:00和RTS-04:00),造成的污染总时长和日平均浓度均最大,不仅部分近地面污染物被海陆热力环流携带至盛行梯度风的上风向区域,并且下风向区域的日平均浓度最高达海陆无温差时的4~5倍.因此,即使在盛行梯度风较强时忽略海陆温差形成的热力环流影响,也会明显低估非海陆风日的实际污染强度和污染范围.