欧洲北美温带地区酸化生态系统的恢复现状与前景

过去20多年来,由于欧美国家采取了强有力的减排措施,从而使这些地区大面积范围的酸沉降率,尤其是硫的沉降普遍下降,但对这些温带地区开展的地表水和陆地生态系统的恢复进程研究显示:随着酸性排放物的减排,酸化生态系统开始有所恢复,但恢复相当缓慢。导致恢复延缓的一个主要原因是低估了氮在酸化中的贡献,另外还有土壤中盐基离子的损耗、干沉降可能被低估、气候的影响等原因。因此酸化生态系统的恢复是一个长期的缓慢的过程,进一步加强酸性排放物尤其是氮的减排,仍然是极为迫切的。

酸雨与森林衰退关系研究综述

酸雨对森林的危害已成为全球性的重要环境问题之一.文中论述了酸雨与森林衰退关系及其不确定性因素,氮素沉降对森林生态系统的影响,以及我国酸雨对森林的危害情况与发展趋势.最后,讨论了酸化生态系统的恢复及其存在的主要问题.

Effects of seawater acidification on the early development of sea urchin Glyptocidaris crenularis

In this study, we evaluated the effects of CO_2-induced seawater acidification on fertilization, embryogenesis and early larval development in the sea urchin Glyptocidaris crenularis, that inhabits subtidal coastal areas in northern China. The range in seawater p H used in experiments was based on the projections of the Intergovernmental Panel on Climate Change(IPCC), to the year 2100. A natural seawater treatment(p H_(nbs) =7.98±0.03) and three laboratory-controlled acidified treatments(OA_1, ΔpH_(nbs) =-0.3 units; OA_2, ΔpH_(nbs) =-0.4 units; OA_3, ΔpH_(nbs) =-0.5 units) were used in experiments. Results show that:(1) there was a negative effect of seawater acidification on fertilization and on the percentage of abnormal fertilized eggs;(2) the size of early cleavage stage embryos decreased in a dose-dependent manner with decreasing p H;(3) both the hatching rate of blastulae and the survival rate of four-armed pluteus larvae decreased as pH declined;(4) larval abnormalities including asymmetrical development, changes in the length of skeletal elements, and corroded spicules were observed in all seawater acidified-treatments compared with the control. These data indicate that seawater acidification has a negative impact on the early development of G. crenularis, and supports the hypothesis that the response of echinoderms to ocean acidification(OA) varies among species. Further research is required to clarify the specific cellular mechanisms involved.

Impacts of Aquaculture and Domestic Wastewater on the Water Quality of Santubong River, Malaysia

Developments along the Santubong River basin may have an impact on the aquatic ecosystem. To determine the impacts of activities on the water quality, ten stations were selected for water quality study over 9 months. Results show that salinity increases from 14.0 PSU upstream to 30.4 PSU downstream. Lowest DO range was 2.3-4.1 mg/L. TSS ranged was 20-135 mg/L and the highest was observed near construction and residential areas, the second and third highest near shrimp culture discharge areas. BOD5 was the highest near construction and residential areas. BOD5 of a station near shrimp culture was not significantly different from the residential areas. Two stations near shrimp culture site also recorded the highest Chl-a. The highest ammonia-nitrogen, nitrite-nitrogen and reactive phosphorus were observed at stations near shrimp farm sites whereas nitrate-nitrogen was the highest near construction and residential areas. Cage culture site showed the highest phosphorus and second highest nitrite-nitrogen and ammonia-nitrogen. This study showed that TSS and BOD5 were elevated near residential and construction areas and nutrients were elevated near shrimp farm sites resulting in algal bloom. Therefore, it is recommended that residential and shrimp farm discharge be treated to acceptable quality before discharge to protect the aquatic resources.

Interactive effects of metal pollution and ocean acidification on physiology of marine organisms

Changes in the global environment such as ocean acidification （OA） may interact with anthropogenic pollutants including trace metals threatening the integrity of marine ecosystems. We analyze recent studies on the interactive effects of OA and trace metals on marine organisms with a focus on the physiological basis of these interactions. Our analysis shows that the responses to elevated CO2 and metals are strongly dependent on the species, developmental stage, metal biochemistry and the degree of environmental hypercapnia, and cannot be directly predicted from the CO2-induced changes in metal solubility and speciation. The key physiological functions affected by both the OA and trace metal exposures involve acid-base regulation, pro- tein turnover and mitochondrial bioenergetics, reflecting the sensitivity of the underlying molecular and cellular pathways to CO2 and metals. Physiological interactions between elevated CO2 and metals may impact the organisms＇ capacity to maintain ac- id-base homeostasis and reduce the amount of energy available for fitness-related functions such as growth, development and re- production thereby affecting survival and performance of estuarine populations. Environmental hypercapnia may also affect the marine food webs by altering predator-prey interactions and the trophic transfer of metals in the food chain. However, our under- standing of the degree to which these effects can impact the function and integrity of marine ecosystems is limited due the scar- city of the published research and its bias towards certain taxonomic groups. Future research priorities should include studies of metal x Pco2 interactions focusing on critical physiological functions （including acid-base, protein and energy homeostasis） in a greater range of ecologically and economically important marine species, as well as including the field populations naturally ex- posed （and potentially adapted） to different levels of metals and CO2 in their environments [Current Zoology 61 （4）： 653-668, 2015].

Nitrate assimilation by marine heterotrophic bacteria

Nitrate assimilation is a process where bacteria utilize nitrate as a nitrogen source and synthesize it into organic nitrogen. We found that nitrate-assimilating bacteria(NAB) are widely distributed in various marine environments, from surface to the deep ocean and sediment, which indicates that NAB are significant to the oceanic nitrogen cycle. Comparative genomic analysis revealed nitrate-assimilating genes(nas A) in these marine heterotrophic NAB showed different gene arrangements and diverse regulation systems. Summary on recent findings will contribute to understanding the process of nitrate assimilation in NAB and their ecological significance in the nitrogen cycle. A systematic analysis of a number of studies on bacterial nitrate assimilation in marine ecological systems was conducted to clarify directions for future research.