Seagrass on the edge: Land-use practices threaten coastal seagrass communities in Sabah, Malaysia

Seagrass meadows are susceptible to coastal environmental impacts and serve as early indicators of system-wide degradation. Two SeagrassNet monitoring sites were established in Sabah (Malaysia) in 2001 in the Tunku Abdul Rahman National Park: one a pristine, reference site and one anticipating impacts from nearby, ongoing waterfront development. At both sites, percent cover of all seagrass species declined significantly between 2003 and 2005. Water temperature, fine sediment and specific leaf biomass increased, while percent surface light intensity reaching the plants decreased. Evidence suggests that the temperature changes observed during the monitoring period were not sufficient to impact seagrasses; rather, the documented reduced subsurface light intensity caused the observed seagrass declines. Concomitantly, satellite imagery revealed a persistent sediment plume in these coastal waters associated with deforestation. SeagrassNet monitoring quickly documented seagrass losses and identified the causal environmental factor, providing timely information for management consideration.     

沉淀值在小麦品质育种上的应用研究

沉淀值是评价小麦品质的一个重要指标,已成为小麦育种工作者重视和经常应用的一个品质指标。以育种实践及前人发表的论著为基础,从沉淀值测定方法,沉淀值与小麦的品质性状、品质改良和环境营养条件等方面加以分析论述,探讨沉淀值在小麦品质育种中的作用,以期为亲本选配、后代选择处理、品质鉴定等提供参考。沉淀值与其他小麦品质指标密切相关,可作为衡量小麦品质的指标之一;沉淀值常用测定方法包括Zeleny法和SDS法,后者又分为常量测定和微量测定,其中微量SDS测定更适合小麦育种过程中的后代品质分析。沉淀值遗传力大,同时也受环境条件影响,育种过程中应注意控制肥力水平,以更好地反映基因型遗传效应。     

Fingerprinting sediment sources in a typical karst catchment of southwest China

Due to the complex hydrogeological conditions in karst regions, it is difficult to measure sediment source contributions at a catchment scale directly. The objective of this study was to quantify the relative contributions of sediment sources and their temporal variability in a karst catchment in southwest China. Karst depressions can trap eroded sediment similar to a dam or reservoir and, thus, are representative and typical test beds for identifying sediment sources in karst regions. Three sediment cores were taken from a karst depression, 58 soil samples from three potential sediment sources were collected, and 18 soil properties were analyzed. The relative contributions of cropland, forestland, and fissure or crack soils were calculated using a multivariate mixing model. The fingerprinting results demonstrated that the cropland was the main sediment source in karst catchment. Specifically, according to the mean sediment contributions of the three deposited sediment cores, the sediment contribution from cropland topsoil was 69.3%, varying from 46.9% to 92.3%, and forestland soil and crack soil accounted for 8.6% and 22.1% of the sediment yield, and varying from 2.8% to 16.5% and 4.8%–36.6%, respectively. This result indicated that great attention should be paid when using only a single core to quantify sediment provenance. Due to the deposited sediment was generally disturbed as cropland in the karst depression, the area that has not been disturbed in recent decades in depression was more appropriate to trace sediment sources in karst catchment. To the best of our knowledge, this study was the first to quantify the contributions of sediment sources in the karst catchment of southwest China. This study provides valuable information and a preliminary reference for applying a composite fingerprinting technique to quantify sediment sources in karst catchments.     

规模化猪场粪污处理工艺的研究

在国内外猪场粪污处理工艺调研的基础上，通过对粪污粒径分布、沉降性能和气浮工艺适用性的试验研究，确定了一种先进实用、可靠、易行的猪场粪污达标排放的处理工艺。     

用沉降法和激光法测定土壤粒度的对比研究

分别用激光粒度仪和沉降法测定了古水稻土剖面100个样品和下蜀黄土剖面105个样品的粒度分布。对两种测定方法所获结果进行了系统的对比分析。研究结果认为:①沿垂直剖面采集的系列样品不适合于讨论两种方法之间的相关性,质地多样化的表层土壤样品组合较适合讨论该问题;②对于黏粒和砂粒来说,两种方法之间的相关性很好,它们的相关系数分别为0.98和0.93,但激光法所测结果低于沉降法。对于粉粒来说,激光法所测结果明显高于沉降法,但两种方法之间的相关性较差;③沉降法和激光法都不可能测得"真实的"粒度,它们的结果反映了同一样品在不同方面表现出的粒度特点。     

Integrated nuclear techniques for sedimentation assessment in Latin American region

The paper shows the novel techniques introduction in the region of Latin America and the Caribbean in order to strengthen the surveillance and monitoring of the sedimentation phenomenon in the surface water reservoirs. The integrated use of the nuclear techniques allows a more complete assessment of water and land sustainability. With the development of a regional project, supported by the International Agency of Atomic Energy, Cuba participates as technical leader for 15 countries, to encourage and implement the integrated application of 3 nuclear techniques (Fallout Radionuclides (¹³⁷Cs, ⁷Be, ²¹⁰Pb), Compound Specific Stable Isotopes (fatty acids of the ∂13C) and the Isotopic Hydrology (¹⁸O, ²H, ³H). The methodology used in the last studies referred to RLA 5076 Project is to apply the integration of these three techniques allows evaluating, in the hydraulic facilities and surface water reservoirs, the negative sedimentation impacts in natural and anthropic process as environmental and social risk. These techniques evaluate the sedimentation process and its synergy, obtaining since the soil quantification in the landscape, definition the soil origin deposited until the dynamic characterization of the water body as soil receptor. The integrated application of these nuclear techniques in the Project RLA-5076 confirms it as a useful tool to support the decisions makers in the definition of the national strategies and programs related to the land and the water resources sustainability. With the support of the IAEA projects in the Latin American and Caribbean region, has been evidenced an important increment in the use of these novel techniques.     

规模化猪场粪污处理工艺的研究

在国内外猪场粪污处理工艺调研的基础上，通过对粪污粒径分布、沉降性能和气浮工艺适用性的试验研究，确定了一种先进实用、可靠、易行的猪场粪污达标排放的处理工艺。     

Late Holocene erosion in NW Anatolia from sediments of Lake Manyas, Lake Ulubat and the southern shelf of the Marmara Sea, Turkey

This paper deals with modern and ancient sedimentation in fresh water lakes and the marine shelf of the southern Marmara region, NW Anatolia, Turkey. Most of the information has been obtained from monitoring of suspended load discharged into two lakes (Manyas and Ulubat) in the last 45 years and from 8 to 11 m thick lacustrine sediments, in addition to radiocarbon-dated shelf sediments. This allows a holistic approach to the drainage basin denudation over time. The results show that the sedimentation rates in the lakes were low 0.22 cm year⁻¹, from 4000 to 2000 years BP and then they increased (0.29 cm year⁻¹) up to sub-recent times and reached 0.44 cm year⁻¹ in the last century. It is suggested that deforestation created high rates of sedimentation in the basins and/or strong denudation of the region during the Late Holocene. This study also shows that for shallow freshwater lakes the calculation of sedimentation rates must include fine particles lost by the outlets and coarse-grained bed load deposited on their shores. In addition, a high rate of sedimentation has been created by short, but repetitive intense depositions. During the last century particularly during the last 45 years, the rate of sedimentation or denudation has increased dramatically in NW Turkey. The two World Wars and mismanagement of the land had important local effects by increasing deforestation and resulting in the present erosive conditions.     

Predicting vertical accretion rates at an archaeological site on the Mississippi River floodplain: Effigy Mounds National Monument,Iowa

The Sny Magill Unit of Effigy Mounds National Monument, Iowa, contains the largest cluster of prehistoric effigy mounds on public land in North America. The mounds are situated atop a low terrace of the Upper Mississippi River, where they are slowly being buried by overbank deposition during floods. The terrace surface includes forest soils with argillic (Bt) or cambic (Bw) horizons developed in up to 1 m of loamy overbank deposits on top of Pleistocene sand and gravel. Radiocarbon evidence suggests that overbank deposits have accumulated since the end of the mound-building period (about 700 years BP), yielding a vertical accretion rate of about 0.6 mm yr^− 1. On the basis of ¹³⁷Cs analysis, accretion rates over the past 40–50 years average 1.25–2.07 mm yr^− 1, with some evidence for a decreasing rate since 1964. If these accretion rates are projected forward, several of the effigy mounds could be buried by flood deposits within 150–300 years. This ¹³⁷Cs-derived estimate agrees closely with an estimate of burial times based on flood frequency and observed flood deposit thickness during recent floods. However, the floodplain and backwater environments of the Upper Mississippi River are aggrading much more rapidly than the Sny Magill terrace surface, suggesting that burial of the entire terrace could occur within 80–400 years and the entire mound group could be buried within 150–850 years. The projected accretion rates and time to burial are subject to large uncertainties because of environmental change in the watershed, including recent trends toward increasing flood stages and decreasing suspended sediment loads.     

一次稳定天气系统下气溶胶沉降过程分析

选取天津地区春末夏初一次空气污染过程,利用安徽光机所研制的Mie散射激光雷达探测资料,结合微波辐射计、地面气象观测数据对天津地区大气气溶胶垂直分布情况进行了研究,并对当时的气象条件及大气边界层逆温特征进行了分析。结果表明,大气气溶胶的沉降过程与能见度的变化具有一定的相关性,在一次连续的观测过程中监测到大气气溶胶随时间有一个明显的沉降过程。气溶胶层层顶下降1 km,当日能见度在相同时段里明显降低,说明气溶胶的沉降对能见度产生了一定的影响。由于逆温层I的存在抑制了大气的垂直运动,逆温层II异常稳定,在较长的时间内未发生明显的变化。天津地区此次空气污染过程中污染物主要为外源性输送。