Huangqihai Lake Research Articles

Semi-quantifying vertical sedimentary succession and microfacies characterization from a delta system in a lacustrine basin, Huangqihai Lake, North China

The formation of vertical sedimentary succession of a delta in the arid and semi-arid basin-margin progradation dramatically depends on the variation of sediment flux and accommodation, but the discontiguous record of signals tends to exist enormously variable, which renders the bulk record of microfacies difficult to quantify from the vertical sedimentary succession. We analyzed the 18 vertical sedimentary successions collected from 18 field trenches of a lake delta by the cusp-catastrophe model, allowing detailed mapping of microfacies. The present detailed study indicates the suitability of cusp-catastrophe theory for explaining vertical sedimentary succession in the BWH (Bawanghe) delta. Three equilibrium states of processes responsible for the deposition of the BWH delta's evolution were established: sandy-dominated upper leaves primarily exhibit the delta plain; sandy/muddy-dominated lower leaves present the delta plain and pro-delta; and sandy-dominated middle leaves which commonly developed the delta front. The result of analysis shows that the reliability of the cusp-catastrophe model to identity mutation of vertical sedimentary succession exceeds 50 %, and to identity microfacies transitions with a precipitation periodicity exceeds 70 %. These cognitions support the previous view that changing precipitation results in an abrupt change in margin progradation. Simultaneously, the study gives new insights into the microfacies quantification of lake deltas and reveals the influence of crest value changes of precipitation on vertical sedimentary succession can be understood from the dependence of microfacies distribution on the change of sediment flux and accommodation.

Vegetation Determines Lake Sediment Carbon Accumulation during Holocene in the Forest–Steppe Ecotone in Northern China

To understand the past carbon accumulation of forest–steppe ecotone and to identify the main drivers of the long-term carbon dynamics, we selected Huangqihai Lake and analyzed the sediment records. We measured the organic carbon content (TOC; %) of sedimentary samples and quantified the carbon accumulation rate (CAR; g C m−2 yr−1). Furthermore, the climate, soil erosion, and vegetation development of the past 6800 years were reconstructed using physicochemical parameters and pollen records. Human activities were also obtained from a 2200-year history record. Our results showed that the CAR was high during 5800~4100 cal yr BP (40~60 g C m−2 yr−1), which is mainly attributed to the high sediment accumulation rate (SAR) during this period. Pearson’s correlation, redundancy analysis and hierarchical variation partitioning analyses suggested that the CAR was influenced by the SAR and TOC, while vegetation dynamics (broadleaved tree percentage and vegetation coverage) and local soil erosion were the main drivers of the TOC and SAR. Especially when the vegetation was dominated by broadleaved forests, the CAR was significantly high due to the high gross primary productivity and carbon density of forest compared with steppe. Our study highlights the direct influence of local vegetation and soil erosion on the CAR, whereas climate might influence indirectly by changing local vegetation and soil conditions. Moreover, our results showed that human activities had positive influences on the carbon accumulation dynamics in this region since 2200 cal yr BP by influencing the SAR.

Holocene Vegetation and Climate Changes in the Huangqihai Lake Region, Inner Mongolia

AbstractA consensus on Holocene climate variability at the modern northern fringe of the East Asian summer monsoon (EASM) region remains elusive. Here, we present a pollen‐based reconstruction of vegetation history and associated climate variations of a sediment core from Huangqihai Lake, central Inner Mongolia. During 10.7 to 8.8 cal kaBP, typical steppe with small patches of forest dominated the lake area, suggesting a moderately wet climate, followed by ameliorating climatic conditions until 8.0 cal kaBP as deduced by the expansion of forest. Typical steppe recovered the lake area between 8.0 and 7.2 cal kaBP, reflecting a deterioration of climatic conditions; in combination with other proxy records in the study region, we noticed that severe aridity was prevailed in the lake area between 8.0 and 7.6 cal kaBP. During 7.2 to 3.2 cal kaBP, abundant tree pollen indicated dominance of forest‐steppe around the lake, marking regionally wet conditions. A notable absence of broadleaved trees after 5.2 cal kaBP reveals a slight drying trend, and climate deterioration from 4.5 to 4.1 cal kaBP might be linked to the 4.2 ka event. After 3.2 cal kaBP, a transition to steppe was associated with dry conditions in the region. Based on our pollen record and prior paleoclimatic reconstructions in the Huangqihai Lake region, there was a generally‐accepted, stepwise shift to a wet climate during the early Holocene, an overall humid climate from 7.2 to 3.2 cal kaBP, and then severe drought for the rest of the Holocene. Moreover, regional comparisons among pollen records derived from lakes situated in the temperate steppe region suggested a roughly synchronous pattern of vegetation and climate changes during the Holocene and demonstrated an intensified EASM during the middle Holocene.

External Groundwater Alleviates the Degradation of Closed Lakes in Semi-Arid Regions of China

There are a large number of lakes with beaded distribution in the semi-arid areas of the Inner Mongolian Plateau, and some of them have degraded or even disappeared during the past three decades. We studied the reasons of the disappearance of these lakes by determining the way of replenishment of these lakes and the impact of the natural-social environment of the basin, with the aim of saving these gradually disappearing lakes. Based on remote sensing image and hydrological analysis, this paper studied the recharge of Daihai Lake and Huangqihai Lake. The deep learning method was used to establish the time-series of lake evolution. The same method was combined with the innovative woodland and farmland extraction method to set up the time-series of ground classification composition in the basins. Using relevant survey data, combined with soil water infiltration test, water chemical, and isotopic signature analysis of various water bodies, we found that the Daihai Lake area is the largest in dry season and the smallest in rainy season and the other lake is not satisfied with this phenomenon. In addition, we calculated the specific recharge and consumption of the study basin. These experiments indicated that the exogenous groundwater is recharged directly through the faults at the bottom of Daihai Lake, while the exogenous groundwater is recharged in Huangqihai Lake through rivers indirectly. Large-scale exploitation of groundwater for agricultural irrigation and industrial production is the main cause of lake degradation. Reducing the extraction of groundwater for agricultural irrigation is an important measure to restore lake ecology.

Spatial modelling of the regulating function of the Huangqihai Lake wetland ecosystem

The regulating function is the least understood but probably most valuable service provided by an ecosystem. To estimate the impact of externalities on the regulating function of a wetland, we modelled the interdependence between activities that affect wetland characteristics and land utilization patterns. Nature-based solutions (NBS) can provide benefits for society, the economy and nature. The NBS solution for wetland bioremediation is proposed through a combination of ecosystem value provided by nature-based or artificial arable land. We constructed a model to simulate the dynamic spatial and temporal changes in the regulating function of a wetland to study the impact of agricultural and fishing activities on the functions and services of a wetland ecosystem. The model was used to determine the relationship between land use change, wetland range, water quality, and fish stocks. Huangqihai Lake (HQHL) is a relatively isolated lake in an area interlaced with agriculture and pasture zones. From 1973 to 2014, the “shrinkage” of the water area of HQHL approached 60%. Under the influence of humans and natural disturbances, the HQHL wetland faced enormous ecological risks, water pollution, area reduction, sharp biodiversity reduction, and fish extinction. The phosphorus (P) concentration seems to be a key factor affecting both the reed growth in the nearshore areas of the Huangqihai Lake wetland and the breeding of phytoplankton in the core lake water area. Dividing this value by the 25,821 ha of the core wetland area affected by the reclamation, the cost per unit of lost fish production is USD$166/ha/yr. After deducting the externalities of the fishery, the net sustainable income from the conversion is USD$1717/ha. The spatial distribution of nutrient load externalities varies with the use of wetlands. In terms of fishery value, the additional nutrient load associated with the conversion of wetland uses would result in a reduction of at least 8% of the maximum sustainable yield. The conversion of wetland uses resulted in the loss of nutrient buffering functions. To compensate for the farmland's nutrient load buffer service, the government should provide arable land farmers USD$8.1 M/yr. It is theoretically feasible to implement an ecosystem service payment system that can effectively compensate for the loss of nutrient buffer function caused by the conversion of wetlands. The approach based on BNS we described may also have value in other ecosystems where regulatory functions include similar mechanisms.

Sedimentology of a topset-dominated, braided river delta of Huangqihai Lake, North China: implications for formation mechanisms

Sedimentary characteristics and genesis of a sandy, topset-dominated braided river delta from Huangqihai Lake were investigated using trenching and a ground penetrating radar survey. Ten lithofacies types were identified with assistance of grain size distribution to record a broad range of depositional processes within an overall coarsening upward sequence. Four distinct architectural elements, including channel fill, compound bar, sand sheet, and river mouth bar, built up this delta. No obvious foreset can be identified in this braided river delta. A gentle slope (0.2°) and shallow basin (<10 m deep), young age (~25 years), and low sediment supply caused by human disturbance and semi-arid climate, are believed to allow this type of topset-dominated delta to form.

Lake level reconstruction of Huangqihai Lake in northern China since MIS 3 based on pulsed optically stimulated luminescence dating

ABSTRACTLake sediments provide rich information about past climatic variations in the drainage area. Five outcrops from Huangqihai Lake in northern China were investigated to reconstruct the lake level fluctuations during the late Pleistocene and Holocene. A chronological framework ranging from ∼34 to ∼8 ka was established by pulsed optically stimulated luminescence dating using sand‐sized quartz and by radiocarbon dating techniques. The chronological and geological evidence demonstrates that the lake level of Huangqihai reached a peak elevation of ∼1340 m [&gt;77 m above the present lake level (a.p.l.l)] during the early Holocene. Such highstand was sustained from ∼10 to ∼8 ka and retreated towards the middle and late Holocene. Between ∼50 and ∼11 ka, aeolian and fluvial deposition prevailed around the lake basin and no lake sediment was found above 1277 m (∼14 m a.p.l.l.), demonstrating a low lake level during this interval compared with that of the early Holocene.

Determinants of soil erosion during the last 1600 years in the forest–steppe ecotone in Northern China reconstructed from lacustrine sediments

Wind erosion of soil in northern China contributes to the environment of East Asia and even the Northern Hemisphere. It is commonly thought that human-induced grassland degradation determines soil erosion in the semi-arid steppe region. In this study, we revealed determinants of soil erosion during the last ~1600years through analyzing lacustrine sediment from Huangqihai Lake in this region. Our results showed that soil erosion indicated by sediment particle size was enhanced during three periods: 1570–1330cal.yr.BP with warm and dry climate, 1250–1000cal.yr.BP with warm and wet climate, and 470–150cal.yr.BP with cold and dry climate. The common feature of vegetation regimes for enhanced soil erosion was replacement of forest by steppe, suggesting that decline in vegetation cover from forest to steppe, which was attributed to climatic changes, might lead to enhancement in soil erosion. The trend of historical soil erosion did not match the steady increase in historical human population in China and the very short history of massive cultivation in southern Inner Mongolia. In summary, our results supported nature- rather than human-dominated soil erosion in the semi-arid steppe region in north China during the last 1600years.

The bounding-surfaces record of a barrier spit from Huangqihai Lake, North China: implications for coastal barrier boundary hierarchy

Ground-penetrating radar and trenching studies of a barrier spit on the north shore of Huangqihai Lake were made, that reveal important implications for the coastal washover barrier boundary hierarchy and interpretations of this depositional record. A four-fold hierarchy bounding-surface model, representing different levels of impact and genesis, is defined. Each level of the hierarchy is enclosed by a distinct kind of surface characterized by different ground-penetrating radar reflection features, sedimentary characteristics (color, grain size, sorting, rounding and sedimentary structures) and origin. We suggest that this hierarchical model can be applied to any coastal washover barrier deposits.

Ground-penetrating radar study of beach-ridge deposits in Huangqihai Lake, North China: the imprint of washover processes

Determining the origin of beach ridges in lacustrine basins can often be problematic. The sedimentary processes responsible for formation of beach ridges on the north shore of Huangqihai Lake were investigated by using ground penetrating radar (GPR). A 400 MHz GPR antenna was used to achieve a high vertical resolution of 0.04–0.08 m. The radar stratigraphy was then determined using principles of seismic stratigraphy. The radar facies (RF) were determined by analyzing internal configuration and continuity of reflections, as well as reflection termination patterns.

The Ground Penetrating Radar facies and architecture of a Paleo-spit from Huangqihai Lake, North China: Implications for genesis and evolution

A paleo-spit is identified from Huangqihai Lake in North China and proposed as a classic example for investigating the influence of lake level changes and storms on the construction of these bodies. Ground Penetrating Radar (GPR) data, collected with a 400MHz antenna, are used together with sedimentologic observations from trenches to define the facies and sedimentary architecture of the spit. Six types of radar surface, both depositional and erosional, were identified. Radar facies bounded by radar surfaces were interpreted from reflection characteristics and termination patterns. Eight different radar facies were identified in the profiles, and we assign these to three groups (inclined, horizontal and irregular). The whole barrier spit system comprises spit bar and salt marsh units, distinguished using GPR profiles. Linked radar and sedimentologic data are used to develop a model for spit bar evolution. The spit was formed during a cycle of lake-level change spanning ~200years. The characteristics of the different building blocks (washover lobes, sheets and swash laminated sands) within the spit bar unit and their depositional regimes are defined and interpreted. Based on the known lake evolution during the Holocene, a relative chronological framework is presented. Two storms in the 1880s and 1960s may have played an important role in building the spit bar.

Historical trends of wetland areas in the agriculture and pasture interlaced zone: A case study of the Huangqihai Lake Basin in northern China

Wetland degradation has become a serious global environmental issue. The agriculture and pasture interlaced zone (APIZ) in China is often close to the transition zone between arid and semi-arid regions, and it is extremely ecologically sensitive and vulnerable to global change. However, reports on changes in wetland areas in such zones are rarely available. Here, we analyzed remote sensing images to quantify the historical change in the wetland area of the Huangqihai Lake Basin located in the APIZ in China. The comparison indicated an excellent agreement between the results from remote sensing images and historical records for the lake area. Our results showed that 73% of wetland area had disappeared during 1976–2010. About 86% of the lost wetland area was converted to grassland, forest, and bare fields, while 14% was converted to cropland and built-up land use types. The largest lake in this basin, the Huangqihai Lake, was in a state of contraction during this period, and it has been completely dry since 2008. A large share (54%) of the lost area of the lake has become marshes, while about 97% of the original marsh area within the basin disappeared during 1976–2010. Without substantial efforts in wetland management and protection, this trend in natural wetland degradation is likely to continue. Mapping wetland areas with remote sensing images is an effective approach to providing wetland area information in a spatially and temporarily explicit way in regions where monitoring programs are not available. Such information is useful for understanding wetland degradation processes, and is helpful for investigating the driving forces of wetland degradation.

Varied responses of forest at its distribution margin to Holocene monsoon development in northern China

Based on pollen analysis and other evidence in a sediment profile from Huangqihai Lake, located at the limit of Asian monsoon influence, the local vegetation development and climatic change were reconstructed for the past 8600years. From 8600 to 7200cal. yr BP, the local vegetation was dominated by steppe and tree cover was low. Then pine increased gradually, and the local vegetation was pine and oak mixed forest with variable ratios of the two dominant tree taxa from 7200 to 3600cal. yr BP. From 3600 to 3000cal. yr BP, the forest was replaced by shrubland, which was attributed to a period of intense drought. From 3000 to 600cal. yr BP, the tree cover declined to its lowest levels, probably due to long-term further drought. After 600cal. yr BP, steppe has become dominant again. We found that the changes of vegetation type indicated by pollen percentages did not match existing evidence for monsoon dynamics. Changes in tree pollen concentration, however, well captured the changes in the Asian monsoon, implying different sensitivity of vegetation cover and vegetation type (e.g. replacement of steppe by forest) to the monsoon development. In addition, a shrubland-dominated stage which has not been evident in previous studies was also clear in our pollen sequences. Our study implied that the responses of marginal forest to drought were variable, depending on the drought regime. The different responses of forest to climate drying in this study provide insights into the reliable prediction of forest dynamics in the semi-arid regions.

Magnetic Fabric Study of Late Holocene Sediments in Huangqihai Lake, Inner Mongolia and its Sedimentary Significance

AbstractThe detailed magnetic susceptibility anisotropy study on the sediments of two sections, which are located in the lake‐center and the lakeshore of the Huangqihai Lake, Inner Mongolia, revealed their hydrodynamics and sedimentary environment changes in the recent 2000 years. The results show that the sediments of two sections both display normal depositional magnetic fabrics, of which the minimum susceptibility axes (K3) are oriented perpendicular to the bedding plane and the maximum magnetic susceptibility axes (K1) lie parallel with the bedding plane. In addition, the lakeshore presents higher magnetic anisotropy degree (P), magnetic foliation (F) and current factor (Fs) than the lake‐center, showing that the lakeshore has higher flow velocity. For the west Huangqihai Lake (HQW) section in the lake‐center, the magnetic matrix grain degree (Q) and the inclination of the minimum susceptibility axes sharply increased and decreased, respectively, at a depth of about 10 cm, 24 cm, 45 cm and 74 cm, which indicate abnormal depositional events with strong kinetic energy. Through comparative analysis, the HQW section can be divided into three stages from top to bottom. The upper stage was a stable depositional environment with strong hydrodynamic energy and low water level, which shows relatively higher Fs value and the Q value varies similarly with P and F. The middle stage was a stable depositional environment with high water level and low hydrodynamic energy, intermitted with high‐energy abnormal events, which shows relatively lower Fs and the Q value was negatively correlated with P and F. The lower stage was an unstable depositional environment with low hydrodynamic energy and high water level, which shows relatively lower P, F, and Fs value.

Timing and possible forcing mechanisms of Huangqihai Lake fluctuations in semi-arid northern China since the late Glacial

Timing and possible forcing mechanisms of Huangqihai Lake fluctuations in semi-arid northern China since the late Glacial

Environmental magnetic comparisons between distal and proximal sediments of Huangqihai Lake, Inner Mongolia, China

Spatial variations in lake sediments are a product of their depositional heterogeneities. To better correlate synchronous strata in Huangqihai Lake, two sections were excavated from the lake-center and the lake-shore. The study involved detailed lithology, mineralogy, and rock magnetic analysis. The results show that the frequency-dependent susceptibility, which is related to the content of super-paramagnetic minerals, is relatively easy to contrast between the two sections. However, mass susceptibility and saturation isothermal remanence, which are related to the content of total magnetic minerals, are difficult to contrast. A possible reason for this difference is that small-particle super-paramagnetic minerals are formed mainly during pedogenic processes, which correlates well with climate change and avoids the effects of local factors when corrections are made at the whole-lake scale. Both sections can be divided into three stages, which appear to be well correlated with previous results obtained through other environmental proxies.

Luminescence chronology for late Quaternary lake levels of enclosed Huangqihai lake in East Asian monsoon marginal area in northern China

Lake level fluctuations of closed lakes in monsoonal regions are direct indicators of regional moisture variability related to the intensity of monsoon activities. In the current study, quartz OSL dating was applied to construct the chronology of two sedimentary sequences from the east and west shores of Huangqihai Lake in the East Asian monsoon area, and the history of lake level fluctuations during the late Quaternary was established. In the current study, we present field investigation findings of highstands of >87 m above the modern lake in enclosed Huangqihai Lake in northern China, and also use luminescence dating to establish the timing for the highstands. We conclude that: (1) Lake highstands occurred during both MIS 5 (>87 m above the modern lake) and early Holocene (∼9–8 ka, >54 m above the modern lake), (2) No highstands were observed for MIS 3 and MIS 2 during which loess has accumulated indicative of much drier climate; (3) The evolution of lakes in East Asian monsoon marginal area (e.g. Huangqihai Lake) is linked with the monsoon variation.

Holocene evolution of Huangqihai Lake in semi-arid northern China based on sedimentology and luminescence dating

The pattern of Holocene palaeoclimatic change in arid-semiarid northern China is debated. The terminal Huangqihai Lake is located at the northern margin of the modern East Asian summer monsoon and sensitive to climate change. We present here a sedimentary section from Huangqihai lake basin which comprises lacustrine and fluvial deposits and is about 8–9 m above the present lake level. Quartz optically stimulated luminescence (OSL) dating was employed to construct the chronology of the section. Based on the OSL chronology and the sedimentological and granulometric analysis, we conclude that (1) the Huangqihai Lake experienced a humid climate during the early part of the Holocene (from c. 10.2 ± 1.0 to 6.7 ± 0.7 ka) with a persistent and stable high lake level; (2) the lake level began to decline indicating aridification between 8.7 ± 0.8 ka and 6.7 ± 0.7 ka, and the climate was drier and variable after 6.7 ± 0.7 ka compared with that of before; (3) from 2.2 ± 0.2 to 0.93 ± 0.07 ka the climatic conditions were highly variable and continuously deteriorating, and the lake was turned into a playa for most of the time. In summary, the climate showed a general drying trend from the early Holocene to the late Holocene.

Environmental change inferred from Rb and Sr of lacustrine sediments in Huangqihai Lake, Inner Mongolia

Based on the geochemical elements Rb and Sr in sediments with three different grain size fractions from profile H3 on the northern lacustrine bottomland 13 m above the Huangqihai Lake surface in 1986, the paper investigates the record of palaeolake stand state, sedimentary environmental evolution, and winter monsoon change. First, these samples are separated into three different grain size fractions, i.e., total sediments, 77-20 μm and <20 μm. Second, the chemical elements—Rb and Sr—of the grain size separation were tested and analyzed systematically in this paper. Then the elements compositions of these samples are measured using VP-320 mode fluorescence spectrum instrument, respectively. The magnetic susceptibility of these samples is measured using Kappabridge KLY-3 mode instrument made in Czech AGICO Company. The results showed the elements and the ratios varied regularly with the grain size. But the ratio of Rb/Sr in the sediments <20 μm correlates positively with the magnetic susceptibility of these samples. Therefore, the ratio of Rb/Sr in the fraction <20 μm from the lake sediments reflected the strengthening of the weathering in the deposition sites. It is a good indicator of the summer monsoon-induced weathering and pedogenesis fluctuations and can be used to reconstruct the conditions of the paleoclimate and paleoenvironment.

Study on fluctuations of closed lake level of huangqihai lake in inner mongcolia since holocene

黄旗海是一封闭湖泊, 气候是控制其湖面变化的主要因素。地貌、沉积物、地球化学分析及历史考古资料均证实, 一万年以来湖面在总体收缩下降过程巾不断地波动着。全新世初期, 湖面扩张抬升, 9000a B.P.前后湖面达最高(1340m), 湖面面积也最大(约560km~2), 其后, 湖面持续地收缩下降。;Huangqihai Lake is an inland closed lake. Climatic change is a major factor to control the lake level fluctuatiunc. The analysis on geomorphology, lacustrine sedimentolugy, geuchemistry and historical archecnugy proves that the lake level has been fluctuating since 10000 a B. P. During the early Holocene, the lake level began rising and reached its maximum height at y000a B. P. ur a maximum area of the lake. Then the lake level began to fall and its surface area to be reduced successively.