Urban structures as marine habitats: an experimental comparison of the composition and abundance of subtidal epibiota among pilings, pontoons and rocky reefs

There remains little understanding of the relationship between the ecologies of urban habitats (pilings and pontoons) and natural habitats (rocky reef) for sessile plants and animals (epibiota) living on urbanised coasts. This study describes the structure of subtidal assemblages of epibiota among pilings, pontoons and adjacent rocky reef in Sydney Harbour, Australia. I tested the prediction that the experimental provision of substrata of the same age and composition in all three habitats would produce assemblages that: (1) differed among all three habitats; and (2) differed most on floating pontoons relative to the two fixed habitats (pilings and reef). As predicted, the results suggested that both pilings and pontoons, particularly the latter, create novel habitats for epibiotic assemblages independent of age and composition of substratum. It is not fully understood why these urban structures act as such different habitats from natural rocky reefs. The important point is that they are different and we are yet to understand the implications of this for the ecology of coastal areas subject to urbanisation.     

Persistence of oiling in mussel beds after the Exxon Valdez oil spill

Persistence and weathering of Exxon Valdez oil in intertidal mussel (Mytilus trossulus) beds in Prince William Sound (PWS) and along the Gulf of Alaska was monitored from 1992 to 1995. Beds with significant contamination included most previously oiled areas in PWS, particularly within the Knight Island group and the Kenai Peninsula. In sediments, yearly mean concentrations of total petroleum hydrocarbons ranged from < 60 micrograms/g in reference beds to 62,258 micrograms/g wet wt., or approximately 0 to 523 micrograms/g dry wt. total polynuclear aromatic hydrocarbons (TPAHs). In mussels, mean TPAH concentrations ranged up to 8.1 micrograms/g dry wt. Hydrocarbon concentrations declined significantly with time in some, but not all mussels and sediments, and should reach background levels within three decades of the spill in most beds. In 1995, mean hydrocarbon concentration was greater than twice background concentration in sediments from 27 of 34 sites, and in mussels from 18 of 31 sites.     

Characteristics analysis of extremely cold weather in the Greater Khingan Mountains region北大核心CSCD

Extremely cold weather has an important influence on winter production and life in the Greater Khingan Mountains region. This paper uses the daily minimum temperature data of ground observation stations during extreme cold weather from 1974 to 2021 in the Greater Khingan Mountains region, monthly circulation index data, the spatial distribution and temporal variation characteristics of extreme cold days and extreme minimum temperature were analyzed by climate statistical method; The abrupt changes and periods of extreme cold days and extreme minimum temperature were tested by Mann-Kendall method and Morlet wavelet analysis; calculating the recurrence period of extreme minimum temperature by empirical frequency method; correlation method was used to analyze the circulation factors which had significant influence on the number of extremely cold days. The results are followed: (1) The spatial distribution of extreme cold days in the Greater Khingan Mountains region was not uniform, and gradually decreasing from northwest to south. The extreme cold days was at most 717 d in Huzhong, and at least 29 d in Gagadaki, the extreme cold days in the whole region mutated in 1979, and the average annual extreme cold days decreased 14.2 d after the mutation compared with that before the mutation, and the annual extremely cold days have a significant cycle of 2 to 4 years. (2) The extreme minimum temperature in the whole region mutated in 1990, before the mutation the extreme minimum temperature was low and after the mutation began to rise, the significant cycle of annual extreme minimum temperature was 4 to 5 years, the extreme lowest temperature was -49.6 ℃ in Mohe, followed by -49.2 ℃ in Huzhong; the extreme lowest temperature occurs once every 2 years, once every 5 years and once every 10 years in Huzhong, while the extreme lowest temperature occurs once in 20 years, once in 50 years and once in 100 years in Mohe. (3) SCAND teleconnection patterm has a good correlation with extreme cold days in winter(January, February and December)in the Greater Khingan Mountains region. Positive growth of the circulation mode, it has great influence on the extreme cold weather in winter in the Greater Khingan Mountains region. © 2022 Science Press (China).     

多年冻土区土壤多环芳烃污染研究进展

多环芳烃（polycyclic aromatic hydrocarbons,PAHs）是一种难降解、毒性强的致癌性污染物,其广泛分布于各环境介质中,陆地环境中90%的PAHs累积在土壤中。随着资源的开发,由油品泄漏、垃圾渗滤、污水排放等行为造成的多年冻土区PAHs土壤污染问题日益突显,并且在气候变化背景下,多年冻土中的PAHs具有重新释放而造成二次污染的风险,多年冻土区土壤多环芳烃污染分布特征和迁移规律研究对评估多年冻土区生态环境风险,防治土壤持久性有机物污染,保障广大多年冻土居民生命健康安全具有重要意义。通过回顾目前国内外多年冻土区土壤中PAHs污染的相关研究,分析发现多年冻土区未受污染的土壤中PAHs的污染水平远低于中低纬度人口密集区域,可代表地球土壤中PAHs的背景值;高纬度或高海拔的地理位置以及严寒的气候使得冻土区土壤中PAHs一个普遍且最重要的来源是大气远距离传输;活动层的冻融作用主要通过改变土壤理化性质和控制水分运移方向影响PAHs在多年冻土区土壤中的垂向分布特征,多年冻土的低渗透性具有阻碍PAHs垂向迁移的作用。综合分析已有研究成果,表明目前冻土区土壤PAHs污染研究还是大量集中于表层土壤中的污染分布调查和来源解析,而关于PAHs在活动层和多年冻土层中的垂向迁移研究还仅限于对其在土壤剖面中分布状况的解释性分析,冻融作用对PAHs在土壤中的迁移、转化和归宿的影响机制还不清楚。未来多年冻土区土壤中PAHs的研究将集中于迁移转化机理与污染治理技术两方面,针对PAHs在多年冻土区土壤中迁移行为的模拟模型亟待研究开发,以实现PAHs污染储量和迁移通量的定量预测;此外,多年冻土区土壤污染问题的深入研究还需要紧密联系多圈层、多界面、多介质、多要素以及多目标污染物而开展。     

Monitoring the sea change: preliminary assessment of the conservation value of nearshore reefs, and existing impacts, in a high-growth, coastal region of subtropical eastern Australia

In northern NSW, Australia, coastal populations are forecast to increase dramatically over the next 25 years (the "sea change"). However, management of the effects of development on marine communities is hampered by the lack of data on key habitats. Consequently, we developed a protocol to assess the biodiversity and current human impacts on nearshore reefs, habitats that will be readily affected by coastal development. We assessed four reefs adjacent to each of three population centres targeting fish, mollusc and sessile benthic communities, and debris loads. Community structure was highly variable over all spatial scales indicating that reefs should not be considered equivalent within the planning framework. While, debris loads were relatively low on most reefs, those with highest conservation value also had the highest debris loads suggesting potential conflict between human use and long-term sustainability of reefal communities. Without intervention, this situation will be exacerbated in the future.     

Hydrogen peroxide production in marine bathing waters: Implications for fecal indicator bacteria mortality

Hydrogen peroxide concentrations [H(2)O(2)] have been measured over the last two decades in multiple studies in surface waters in coastal, estuarine and oceanic systems. Diurnal cycles consistent with a photochemical production process have frequently being observed, with [H(2)O(2)] increasing by two orders of magnitude over the course of the day, from low nM levels in the early morning to 10(2)nM in late afternoon. Production rates range from <10 for off-shore ocean waters to 20-60nMh(-1) for near-shore coastal and estuarine environments. Slow night-time loss rates (<10nMh(-1)) have been attributed to biological and particle mediated processes. Diurnal cycles have also frequently been observed in fecal indicator bacteria (FIB) levels in surf zone waters monitored for microbial water quality. Measured peak peroxide concentrations in surface coastal seawaters are too low to directly cause FIB mortality based on laboratory studies, but likely contribute to oxidative stress and diurnal cycling. Peroxide levels in the surf zone may be increased by additional peroxide production mechanisms such as deposition, sediments and stressed marine biota, further enhancing impacts on FIB in marine bathing waters.     

Semipermeable membrane devices link site-specific contaminants to effects: Part 1 - Induction of CYP1A in rainbow trout from contaminants in Prince William Sound, Alaska

Extracts from semi-permeable membrane devices (SPMDs) deployed on beaches in Prince William Sound (PWS), Alaska, were used to evaluate if complex contaminant mixtures from different sources can be distinguished by the resulting cytochrome P450 1A (CYP1A) activity in exposed test animals. Deployment sites included canneries, salmon hatcheries, and beaches where lingering oil remains from discharges during the 1964 earthquake or the 1989 Exxon Valdez oil spill. Other sites were selected at random to evaluate region-wide contaminant inputs or were located in salmon streams to evaluate contaminants carried and released by migrating salmon carcasses following reproduction. Following standard deployments of approximately 28 d, an aliquot of the accumulated contaminants was intraperitoneally injected without cleanup into juvenile rainbow trout (Oncorhynchus mykiss). After 2 d and 7 d, the activity of CYP1A was measured by the ethoxyresorufin-o-deethylase (EROD) assay. Exposure to extracts from the oiled sites and one hatchery site with numerous creosote pilings elicited strong EROD responses, whereas fish exposed to salmon stream extracts elicited weak but significant responses during late summer compared to late spring. Responses from the other sites were not significant, indicating contaminants from these sources are unlikely to cause CYP1A induction in resident biota. Rather than simply assessing extant contaminants, this method evaluates the potency of the different sites for bringing about aryl hydrocarbon receptor responses in resident biota.     

Marine debris: A proximate threat to marine sustainability in Bootless Bay, Papua New Guinea

Surveys of stranded marine debris around Motupore Island, a small island in Bootless Bay, Papua New Guinea, revealed exceptionally high loads (up to 78.3itemsm(-2)), with major concentrations in mangrove-dominated, depositional areas. The worst affected, 50-m stretch of shore was estimated to contain >37.000 items with a combined weight of 889kg. Consistent with studies elsewhere, plastics comprised by far the majority of debris across all sites (89.7%). The lack of centralised waste collection and limited village-based resources, coupled with an increasing population, suggests that this issue is a long way from solution. High debris loads thwart attempts to rehabilitate depleted mangrove forests through smothering of seedlings, perpetuating run-off and water quality issues in the bay. Addressing marine debris is thus of fundamental importance for the sustainability of Bootless Bay and its resources, and a critical step in promoting ecosystem resilience.     

动荷载作用下冻土温度变化及强度损失探讨

动荷载测温试验发现,初始温度为-6℃的冻土试样,当有循环荷载作用时,随着时间的变化即使外界恒温供冷,其中的温度仍旧会出现上升趋势,并且上升值与加载频率、动应力幅、及试样的干密度、含水率等因素有关.此外,在不同的条件下冻土强度表现出了不同程度的损失.